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Impacts of climate change on surface water quality in relation to drinking water production


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Besides climate change impacts on water availability and hydrological risks, the consequences on water quality is just beginning to be studied. This review aims at proposing a synthesis of the most recent existing interdisciplinary literature on the topic. After a short presentation about the role of the main factors (warming and consequences of extreme events) explaining climate change effects on water quality, the focus will be on two main points. First, the impacts on water quality of resources (rivers and lakes) modifying parameters values (physico-chemical parameters, micropollutants and biological parameters) are considered. Then, the expected impacts on drinking water production and quality of supplied water are discussed. The main conclusion which can be drawn is that a degradation trend of drinking water quality in the context of climate change leads to an increase of at risk situations related to potential health impact.
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Review article
Impacts of climate change on surface water quality in relation
to drinking water production
I. Delpla, A.-V. Jung, E. Baures, M. Clement, O. Thomas
School of Public Health (école des Hautes études en Santé Publique), Laboratoire d'étude et de Recherche en Environnement et Santé (LERES), Avenue Professeur Léon Bernard,
35043 Rennes Cedex, France
abstractarticle info
Article history:
Received 13 March 2009
Accepted 3 July 2009
Available online 29 July 2009
Climate change
Water quality
Extreme events
Organic carbon
Besides climate change impacts on water availability and hydrological risks, the consequences on water
quality is just beginning to be studied. This review aims at proposing a synthesis of the most recent existing
interdisciplinary literature on the topic. After a short presentation about the role of the main factors
(warming and consequences of extreme events) explaining climate change effects on water quality, the focus
will be on two main points. First, the impacts on water quality of resources (rivers and lakes) modifying
parameters values (physico-chemical parameters, micropollutants and biological parameters) are consid-
ered. Then, the expected impacts on drinking water production and quality of supplied water are discussed.
The main conclusion which can be drawn is that a degradation trend of drinking water quality in the context
of climate change leads to an increase of at risk situations related to potential health impact.
? 2009 Elsevier Ltd. All rights reserved.
1. Introduction .............................................................. 1225
2. Impacts on water quality parametes .................................................. 1226
2.1. Basic parameters ........................................................ 1226
2.2. Dissolved Organic Matter .................................................... 1226
2.3. Nutrients............................................................ 1228
2.4. Inorganics micropollutants ................................................... 1228
2.5. Organics micropollutants .................................................... 1229
2.6. Pathogens ........................................................... 1229
2.7. Cyanobacteria and cyanotoxins ................................................. 1229
2.8. Water quality indicators ..................................................... 1229
2.9. Synthesis ............................................................ 1229
3. Expected impacts on drinking water production ............................................. 1230
3.1. DBPs determinants ....................................................... 1230
3.2. Potential impacts ........................................................ 1230
3.3. Monitoring and modeling of impacts ............................................... 1231
3.4. Synthesis ............................................................ 1231
4. Conclusion .............................................................. 1232
Acknowledgments.............................................................. 1232
References ................................................................. 1232
Environment International 35 (2009) 12251233
? Corresponding author. Tel.: +33 2 99 02 29 20; fax: +33 2 99 02 29 29.
E-mail address: Olivier.Thomas@ehes (O. Thomas).
0160-4120/$ see front matter ? 2009 Elsevier Ltd. All rights reserved.
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1. Introduction
Floods and droughts are the main impacts of climate change on
water availability. Besides these quantitative impacts, surface water
quality is also affected by climate change. For example, it seems
obvious that a drought may imply at least a modi?cation of surface or
ground water quality (concentration) sometimes leading to water
supply limitation. If surface water withdrawal can be directly affected
by water quality degradation, wells pumping can be cut off for sanitary
reasons (groundwater quality) as well as for security reasons (?oods
threats). However, even if these facts are well known, few scienti?c
works have been published until recently on the impacts of climate
change on water quality modi?cation.
Actually, climate change is not the only factor affecting water quality.
Integrated i nto th e global change concept, land use evolution,
deforestation, urban spreading and area waterproo?ng may also
contribute to water quality degradation. But more often, water pollution
is directly linked to human activities of urban, industrial or agricultural
origin, and climate change could lead to degradation in surface water
quality as an indirect consequence of these activities. When point source
pollution is reduced in many countries (even if wastewater treatment
plants begin to reach their capacity limits), climate (global) change
impacts could tend to increase the diffuse pollution with for example
urban or agricultural runoff. The climate change determinants affecting
water quality are mainly the ambient (air) temperature and the increase
of extreme hydrological events. Soil drying-rewetting cycles and solar
radiation increase may also be considered.
First of all, temperature (in general) must be viewed as the main
factor affecting almost all physico-chemical equilibriums and biologi-
cal reactions. It is well known that all physico-chemical constants
vary with temperature, and frequently increasin g en dotherm ic
reactions. According to Arrhenius relation, kinetic of a given chemical
reaction can be doubled for a temperature incre ase of 10 °C.
Consequently, several transformations or effects related to water will
be favoured by water temperature increase such as dissolution,
solubilisation, complexation, degradation, evaporation, etc. This
phenomenon globally leads to the concentration increase of dissolved
substances in water but also to the concentration decrease of dissolved
gazes. This last point is very important with respect to dissolved
oxygen in water. In fact, its saturation concentration decreases of
almost 10% with a 3 °C increase (10 mg/L at 15 °C). Remind that,
whatever the IPCC scenario, the average global air temperature should
increase between 1.8 and 4.0 °C (Bates et al., 2008) during the 21st
century. M oreover, a drying tendency in summer is expected,
particularly in subtropics, low and mid-latitudes, in addition with an
extreme events increase in general (Bates et al., 2008).
Floods and droughts will also modify water quality by direct effects
of dilution or concentration of dissolved substances. For low river ?ow
rates, the main effect on water quality is as for a temperature increase,
a concentration increase of dissolved substances in water but a
concentration decrease of dissolved oxygen (Prathumratana et al.,
2008; Van Vliet and Zwolsman, 2008). A correlative positive effect is
the concentration decrease of some pollutants due to a low water
velocity (aquatic plants assimilation of nutrients and adsorption/
complexation of heavy metals on suspended matter and settling).
These phenomenons will be detailed hereafter. For heavy rain falls and
strong hydrologic conditions, runoff and solid material transportation
are the main consequences. For countries in the temperate zone,
climate change will decrease the number of rainy days but increase
the average volume of each rainfall event (Brunetti et al., 2001; Bates
et al., 2008)). As a consequence, droughtrewetting cycles may impact
water quality as it enhances decomposition and ?ushing of organic
matter into streams (Evans et al., 2005).
Solar irradiation increase could also alter water quality and
especially characteristics of natural organic matter in freshwaters
systems both by warming and UVB radiation (increasing photolysis)
(Soh et al., 2008). Phototransformation should be seriously taken into
account when evaluating the possibility of formation of UV transfor-
mation products from organic micropollutants such as pharmaceu-
ticals (Canonica et al., 2008). Many papers consider pharmaceuticals
to be photo reactive substances (
Boreen et al., 2003; Buerge et al.,
2006; Petrovic and Barceló, 2007).
This paper aims at reviewing the main impacts on water quality
parameters, generally described for surface water (rivers and lakes),
and the expected impacts on drinking water production.
2. Impacts on water quality parametes
Water quality parameters can be classi?ed according to i) physico-
chem ical basic parameters (temperature, pH, dissolved oxygen,
dissolved organic matter ) and nutrients, ii) micropollutants
(inorganic and organic) including metals, pesticides and pharmaceu-
ticals, and iii) biological parameters with pathogens microorganisms,
cyanobacteria and water quality proxies (Table 1).
2.1. Basic parameters
A rise in surface water temperatures was observed since the 1960s in
Europe, North America and Asia (0.22 °C), mainly due to atmospheric
warming in relation to solar radiation increase (Bates et al., 2008). In
European rivers,Zwolsman and van Bokhoven (2007),andVan Vliet and
Zwolsman (2008) observed an average increase in water temperature of
around 2 °C respectively in Rhine and Meuse rivers after the severe
drought of 2003, with a pH increase (re?ecting a decrease in CO
concentration), and a decrease in dissolved oxygen (DO) solubility
re?ecting a lower DO solubility under higher water temperatures. A DO
decrease can also be associated to an increase in DO assimilation of
biodegradable organic matter by microorganisms (linked to an increase
in Dissolved Organic Carbon (DOC)) (Prathumratana et al., 2008). In the
same study dealing with the surface water quality in the lower Mekong
River, negative signi?cant correlations were generally found between
precipitation (or discharge ?ow) and DO, pH and conductivity (from 0.2
to 0.9). In several lakes in Europe and Northern America, the strati?ed
period has lengthened by 23 weeks and water temperatures have risen
of 0.2 to 1.5 °C, which have an in?uence on thermal strati?cation
(Komatsu et al., 2007)andlakeshydrodynamics(Bates et al., 2008).
Computer models predict an increase of around 2 °C by 2070 in
European lakes, although this rise will also depend on lake character-
istics and season (George et al., 2007; Malmaeus et al., 2006). It has been
demonstrated that shallow lakes are likely to be the most vulnerable to
climate change. Water temperatures have an impact on internal lake
processes like diffusion, mineralization and vertical mixing (Malmaeus
et al., 2006). Residence timeof lakes would probably increase in summer
by 92% in 2050 for lakes with short residence times George et al. (2007).
Also, it is predicted that especially shallow lakes will experience an
increase of temperature in epilimnion and hypolimnion during summer
(J?hnk et al., 2008), although man-made lakes (in The Netherlands)
respond even more directly to weather variations (Mooij et al., 2005).
Nevertheless, deepest lakes are most sensitive to climate warming on a
long period of time due to their greater heat storage capacity and will
consequently show the highest winter temperatures (George et al.,
2007). An increase in water temperature has also an impact on lakes
chemical processes with increases in pH and greater in-lake alkalinity
generation (Psenner and Schmidt, 1992). Concerning the impacts of the
predicted increase in winter precipitations on lake waters, it depends on
the lake size. Small lakes with short residence times will be particularly
sensitive to a change in rainfalls (George et al., 2007).
2.2. Dissolved Organic Matter
Dissolved Organic Matter (DOM) affects the functioning of aquatic
ecosystems through its in?uence on acidity, trace metal transport,
1226 I. Delpla et al. / Environment International 35 (2009) 12251233
Table 1
Impacts of climate change on water quality parameters.
Water quality parameter
CC factors
affecting WQ
Water body Reference Comments
pH Droughts River Van Vliet and Zwolsman, 2008 Higher maximum values in Meuse river.
Lakes Bates et al., 2008 Increase in pH.
River Prathumratana et al., 2008 Negatively correlated (Mekong).
Droughts and
Rivers and lakes Zwolsman and van Bokhoven, 2007;
Komatsu et al., 2007;
Van Vliet and Zwolsman, 2008
Lower dissolved oxygen solubility and concentration.
River Prathumratana et al., 2008 Negatively correlated (Mekong).
Droughts and
Rivers Zwolsman and van Bokhoven, 2007;
Van Vliet and Zwolsman, 2008;
Ducharne et al., 2007; Bates et al., 2008
Warming of the water column.
J?hnk et al., 2008; Komatsu et al., 2007;
Malmaeus et al., 2006; Mooij et al., 2005;
George et al., 2007
Increase in the epilimnion and hypolimnion, especially in shallow lakes.
Increase of temperature, stability of the water column and summer water residence times.
Temperature and
rainfalls increase
Streams and lakes
Monteith et al., 2007; Evans et al., 2005;
Worral et al., 2004; Hejzlar et al., 2003
DOC increase (UK, Scandinavia, Czech Republic, Northeastern USA and Canada).
Clark et al., 2008; Prathumratana et al., 2008
DOC ?ux increase during storm events (UK and Mekong basin).
Droughts River Van Vliet and Zwolsman, 2008;
Zwolsman and van Bokhoven 2007
Sediment release during droughts. Ammonium increase.
Surface and
Wilhelm and Adrian, 2008 Increase mineralization and release of N, C and P from soil OM.
Wilhelm and Adrian, 2008; Jackson et al., 2007;
Malmaeus et al., 2006; Komatsu et al., 2007;
Petterson et al., 2003
Sediment nutrients release and pulses into the euphotic zone.
Strong changes in nutrient loading in shallow lakes.
Elevated phosphate and ammonium concentrations in the hypolimnion during the warm period.
Temperature and
rainfalls increase
River basins, lake,
fjord and
Kaste et al., 2006; Arheimer et al., 2005;
Ducharne et al., 2007; Zhu et al., 2005;
Wilby et al., 2006; Weyhenmeyer, 2008
Increase N river loading (Norway) and nitrate load (UK river and Seine groundwater).
Increase N and P (Sweden) and nutrients (Canada) loading.
Climate change effects could be comparable between small and large lakes.
Heavy rainfalls
Stream and lakes Drewry et al., 2009; Mooij et al., 2005;
Prathumratana et al., 2008
Australia, Mekong basin. Increased P loading of Dutch lakes.
Forested watershed
Bhat et al., 2007 Total Kjeldahl nitrogen (TKN) loading increase (USA).
Inorganics Metals Droughts River Van Vliet and Zwolsman, 2008;
Zwolsman and van Bokhoven, 2007
Selenium, Baryum, mercury, zinc, cadmium, lead and nickel increase.
High alpine lakes Thies et al., 2007 Increasing amount of snowmelt lead to a micropollutants increase (European Alps).
Heavy rainfalls
Streams Rothwell et al., 2007 Correlations between DOC and metals mobilisation (UK).
Temperature and
rainfalls increase
Stream Pédrot et al., 2008 Humic and fulvic acids mobilized various trace elements (Brittany).
Olivie-Lauquet et al., 2001
Trace element release coincide with a decline in redox potential and increase
of organic carbon content (Brittany)
Pesticides Temperature and
rainfalls increase
Surface &
Bloom?eld et al., 2006 Changes in rainfalls intensity and seasonality and increased temperatures are main
climate drivers for changing pesticides fate and behaviour.
Drying and
rewetting cycles
Lennartz and Louchart, 2007 Soil drying increased the biding of herbicidal compounds.
Rainfalls increase
Streams Probst et al., 2005 Increased precipitations lead to an increase of pesticides ?ux.
Groundwater Massman et al., 2006 Arti?cial recharge pond. Change in redox conditions (anaerobic conditions)
with an increase in temperature (Deutchland).
Streams Lissemore et al., 2006 Correlations between DOC and pharmaceuticals concentrations in water.
Oppel et al., 2004
Clo?bric acid and iopromide are very mobile and could contaminate groundwaters through rivers.
Pathogens Temperature and
rainfalls increase
Surface waters Charron et al., 2004; Curriero et al., 2001 Half the waterborne disease outbreaks in USA during the last half century followed a period of
extreme rainfall.
Hunter, 2003; Pednekar et al., 2005
Nearly 70% of the variability in the coliform record is due to seasonal and
interannual variability in local rainfall.
Temperature and
rainfalls increase
Lakes Arheimer et al., 2005; J?hnk et al., 2008;
Hunter, 2003
Summer heatwaves boost the development of Cyanobacteria blooms (Nederlands and Sweden).
Lakes Brient et al., 2008; Wiedner et al., 2007 Cylindrospermopsis Raciborskii northern spread. Microcystin blooms during hot summers.
Fishes, green algae, diatoms
Freshwaters Daufresne et al., 2003; Daufresne and Bo?t, 2007 Pollutants uptake rate increase due to an increased metabolic rate and decrease in oxygen
solubility. Species predominance and abundance changes.
Soils Sardans et al., 2008 Increase enzymatic activity.
1227I. Delpla et al. / Environment International 35 (2009) 12251233
light absorbance and photochemistry and, energy and nutrient supply
(Evans et al., 2005). The principal source of DOM in surface waters is
soil leaching (Hejzlar et al., 2003). Furthermore, positive spatial
relationships between Dissolved Organic Carbon (DOC) export and
wetland areas like peatlands have been demonstrated (Evans et al.,
2005). Since the 1980s, various studies have shown signi?cant DOC
increases in Northern Europe (Evans et al., 2005; Monteith et al.,
2007; Worrall et al., 2004), Central Europe (Hejzlar et al., 2003) and
Northern America (Monteith et al., 2007). Many potential factors (air
temperature, increase in rainfalls intensity, atmospheric CO
and decline in acid deposition) have been proposed to explain these
trends in DOC, although there is no scienti?c consensus. Evans et al.
(2005) h ave shown that recovery from acidi?cation and water
temperature are potential drivers, since many compounds forming
part of DOC are acidic. In fact, a decrease in acid deposition is observed
resulting partly from a decrease in anthropogenic sulphur emissions
(industries, passengers/goods transportation)(Monteith et al.,
2007; Evans et al., 2008). This could lead to an increase in soil pH
and consequently to an organic acids increase permitted by new redox
conditions. Nevertheless, trends in DOC are probably resulting from a
combination of various factors, including acid deposition, since
increasing trends have begun in a few places before reduction in
acid deposition (Worrall and Burt, 2007).
According to Clark et al. (2008), a variation in stream ?ow can be a
good indicator of changes in DOC concentration in streams draining
organo-minerals soils, although the same is false for peat soils (in this
case, temperature is better). Finally, Prathumratana et al. (2008)
shows that COD (Chemical Oxygen Demand), used as an indicator of
Natural Organic Matter (NOM), have weak to fair signi?cant
correlations with precipitations and discharge ?ows for the Mekong
River (from 0.3 to 0.4).
Finally, Prathumratana et al. (2008) shows that COD (Chemical
Oxygen Demand), used as an indicator of Natural Organic Matter
(NOM), have weak to fair correlations with precipitations (0.295
0.426) and discharge ?ows (0.3120.324).
2.3. Nutrients
An increase of N mineralization in soil due to an increase in mean
soil temperature is expected (Ducharne et al., 2007). Moreover,
droughts increase the soil extractible Total Organic Carbon (TOC)
concentration in winter and warming increases extractible nitrate in
summer and autumn and extractib le ammonium in winter. A
moderate increase in soil temperature (spring, summer and winter)
could lead to a large increase in enzymatic activity. Temperature is
positively correlated with nitri?cation process (increasing phospha-
tases activity and P mobilisation in soils). Changes observed in
enzymatic activity are linked with direct effect of soils warming which
stimulates biological activity and increases N availability (Sardans et
al., 2008). Soil warming increases soil extractable nitrates concentra-
tion in summer and autumn (N losses facilitated) and concentration of
extractable ammonium in winter.
Water bodies quality is subjected to weather seasonality which has
an important impact on their nutrient patterns (Zhu et al., 2005). A
warmer climate will create indirect impacts on water bodies like an
increase nutrients load in surface and groundwater (Van Vliet and
Zwolsman, 2008) and counteract policies effects of external nutrient
loading reduction (Wil helm and Adrian, 2008). Indeed, higher
temperatures will increase mineralization and releases of nitrogen,
phosphorus and carbon from soil organic matter. Moreover, an
increase in runoff and erosion due to greater precipitations intensity
should result in an increase in pollutants transport, especially after a
drought period. Higher ammonium concentrations could be observed
in rivers with a reducing dilution capacity caused by droughts
(Zwolsman and van Bokhoven, 2007; Van Vliet and Zwolsman,
2008). Furthermore, release of phosphorus from bottom sediments
in strati?ed lakes is expected to increase, due to declining oxygen
concentrations in the bottom waters (
Wilhelm and Adrian, 20 08).
Regional and global climate scenarios and models are useful tools
to produce data inputs for hydrological models in order to understand
and predict the potential effects of climate change on water bodies. An
increase in dry summertime frequency may lead to gradually mobilize
nitrogen in soils that would be ?ushed into streams at the beginning
of the wet season and cause higher rivers nitrate concentrations
(Wilby et al., 2006). Ducharne et al. (2007) predict an increase in
nitrate concentration in the Seine basin aquifer layers for the years
2050 and 2100 due to an increase in precipitations and consequently
in soil leaching. Kaste et al. (2006) and Arheimer et al. (2005)
respectively predict a 4050% increase in nitrate ?ux by 20702100 in
a Norwegian river basin, and an increase in phosphorus (50%) and
nitrogen (20%) in a lake. Correlations between precipitations, air
temperature, discharge ?ow and phosphates, nitrates and Total
Phosphorus (TP) in the Mekong River have also been observed
(Prathumratana et al., 2008). These results are in accordance with
Bhat et al. (2007) who found that 73% of the total Kjeldhal nitrogen
load at a forested watershed outlet was exported by surface runoff
during storm events. Drewry et al. (2009) also found positive
correlations between TP, total nitrogen, suspended solids and ?ow. It
was also suggested that a major part of the phosphorus is adsorbed
onto suspended solids.
For lakes, higher phosphate and ammonium concentrations in the
hypolimnion are frequently observed during the warm period in
temperate countries (Petterson et al., 20 03 ). Climate change impact
these ecosystems with various manners: changes in temperature, ice-
cover, wind and precipitation (Mooij et al., 2005 ). P loading
exportation, which is governed by discharges following heavy rain
falls, will tend to increase with climate change and consequently have
an impact on lakes ( Mooij et al., 20 05 ). Conversely, streams nitrogen
concentrations are less dependent on stream discharge (Mooij et al.,
2005). Increasing temperatures is supposed to decrease nitrate
concentrations in lakes with an increase in denitri?cation rate and
higher N losses in upstream-situated soil and surface waters (Mooij et
al., 2005). On the contrary, the internal P loading increases thanks to
microbial decomposition of lake sediments (Jackson et al., 2007).
Accumula tion of so luble hypolimne tic phosp hor u s depends on
thermocline depth and hypolimnetic temperatures (Wilhelm and
Adrian, 2008). Indeed, higher hypolimnetic temperatures increase
both mineralization of organic hypolimnetic matter and phosphorus
release from sediments. Dramatic nutrient pulses into the euphotic
zone could be observed after heatwaves (Wilhelm and Adrian, 2008).
Hence, alternating mixing and long strati?cation events threat more
especially polymictic lakes than dimictic lakes ( Wilhelm and Adrian,
2008). P increases in the surface layer, fueling phytoplankton growth
(Jackson et al., 2007), leading to algal blooms and a deterioration of
water quality (Komatsu et al., 2007). Lastly, concerning Total Phos-
porous (TP) concentrations, higher temperatures may impact mainly
lakes with long residence times (Malmaeus et al., 2006), even though
rates of change of phosphate and nitrates concentrations seem to be
independent of lake morp顺心彩票try (Weyhenmeyer, 2008).
2.4. Inorganics micropollutants
In Western Europe, metal concentrations in rivers have greatly
decreased in the past decades with industrial and urban wastewater
treatment efforts. Nevertheless, droughts may have impacts on river
water quality (Zwolsman and van Bokhoven, 2007; Van Vliet and
Zwolsman, 2008), depending on the compound properties that could
be as well either negative or positive. First of all, signi?cantly higher
concentrations for barium, selenium and nickel were observed in river
Meuse during the drought of 2003 (Van Vliet and Zwolsman, 2008).
Conversely, signi?cantly lower concentrations of total lead, chromium,
mercury and cadmium were measured within the same period. These
1228 I. Delpla et al. / Environment International 35 (2009) 12251233
differences are mainly due to dissimilarities between adsorption
capacities by suspended solids but discrepancies exist between
studies. Indeed, in the Rhine river, it was observed that droughts
have a negative impact on metal concentrations of cadmium,
chromium, mercury, lead, copper, nickel and zinc which were higher
during the 2003 drought than during reference periods (Zwolsman
and van Bokhoven, 2007).
Thies et al. (2007) have studied high alpine lake waters (Alps)
response to climate warming and observed a solute release from an
active rock glacier ice. Surface waters over metamorphic rocks were
affected by the rising export of ions and heavy metals from meltwater.
They predicted that high mountain freshwater will thus become
increasingly affected by climate warming.
Furthermore, a strong complexation of some metals by DOC could
lead to a transport of dissolved lead, titane and vanadium in peatland
systems after a storm?ow (Rothwell et al., 2007). A seasonal change in
dissolved metal concentrations was also observed for various trace
elements (Fe, Mn, Al, La, U, Th, Cd and As). An increase of organic
carbon content and a decline in redox conditions seem to be related
with a trace elements release. A positive correlation is also found
between storm events and trace element concentrations in streams
(Olivie-Lauquet et al., 2001). In fact, organic and inorganic colloids
could play an important role in trace elements mobilisation in soils
and water (Pédrot et al., 2008).
2.5. Organics micropollutants
Surface waters are the main receptors for pesticides contamination
from the agricultural use. Bloom?eld et al. (2006) observed that
changes in rainfall seasonality and intensity and increased air
temperatures are the main climate drivers for changing pesticides
fate and behaviour, although effects of climate change are likely to be
variable and dif?cult to predict.
Lennartz and Louchart (2007) has studied the physico-chemical
interactions between soil organic matter and herbicidal compounds
(diuron and terbuthylazine) after drying and rewetting cycles to
examine impacts of climate induced soil water status variations.
Results show that variations in soil water contents modify the soil
organic matter structure, which hinder diffusion and trap pesticides.
An increase in extreme events with climate change will probably
counteract pesticides reduction measures. Probst et al. (2005)
simulate pesticides entries into streams and found, with a heavy
rainfalls scenario (precipitation increase from 10 to 20 mm/day), that
isoproturon and bifenox could potentially present a greater risk due to
their ecotoxicity.
For pharmaceuticals, in a Southern Ontario watershed, Lissemore
et al. (2006) found signi?cant correlations between DOC and some
active substances frequently detected in water (monensin and
carbamazepine), with concentration variations of monensin, linco-
mycin, sulfamethazine, trimethoprim and carbamazepine depending
on ?ow rate and precipitation amount. Furthermore, clo?bric acid and
iopromide are found to have an important leaching potential which
could represent a long term risk for groundwater contamination from
river water through sediment and subsoil (Oppel et al., 2004),
especially in case of heavy rainfalls events.
2.6. Pathogens
Waterborne pathogens could be spread within the freshwater after
a contamination by animal or human waste due to heavy rainfall
discharge in combined sewer systems (CSS). When the ?ow exceeds
the CSS capacity, the sewers over?ow directly into surface water body
(Charron et al., 2004). Pednekar et al. (2005) have studied coliform
load in a tidal embayment and shown that stormwater coming from
the surrounding watershed is a primary source of coliform. Moreover,
higher water temperatures will probably lead to a pathogen survival
increase in the environment, although there is still no clear evidence
Hunter, 2003).
Floods often led to a contamination of groundwater and additional
disease outbreaks like Acanthamoeba keratitis in Iowa (USA) in 1994
(Hunter, 2003). According to Curriero et al. (2001), half of the
waterborne disease outbreaks in the US during the last half century
followed a period of extreme rainfall. Even though the risk of diseases
outbreaks linked to mains drinking waters is low in developed
countries, private supplies would be at risk (Hunter, 2003). In
addition, an increase in temperature threats water quality with regard
to waterborne diseases especially cholera disease in Asia and South
America (Hunter, 2003). Lastly, it was shown that with increased UV
radiation due to ozone layer depletion, NOM trap higher levels of UV
energy and breaks down to more bioavailable organic compounds,
minerals and micronutrients. All these processes could stimulate
bacterial activity in aquatic ecosystems (Soh et al., 2008 ).
2.7. Cyanobacteria and cyanotoxins
Competition between phytoplankton and cyanobacteria could be
switch in favor of cyanobacteria in a warmer climate (Arheimer et al.,
2005) and could also increase their dominance. A higher phosphorus
?ux in the epilimnion can promote phytoplankton growth in the
euphotic layer and lead to an evolution from a macrophyte-dominated
clear water state to a phytoplankton-dominated turbid state. Increase in
water temperatures and nutrient concentration causes massive cyano-
bacteria bloom in many waterbodies (Hunter, 2003). Summer heat-
waves could also boost the cyanobacteria development in lakes through
reducing vertical turbulent mixing and increasing growth rates (J?hnk
et al., 2008). Moreover, new cyanobacterium species as Cylindrosper-
mopsis raciborskii have colonized northern habitats due to effects of
rising temperatures. This tropical cyanobacterium, known to produce
Cylindrospermopsin, is now detected in South and Western Europe
freshwaters (Italy, Spain and France) (Brient et al., 2008) and has been
detected in German lakes (Wiedner et al., 2007). Moreover, an earlier
annual warming in temperate countries permits an earlier and more
important growth of this alga (Wiedner et al., 2007). Lastly, other
cyanobacteria, like Microcystis which can produce microcystin, could
become invasive with climate warming (J?hnk et al., 2008).
2.8. Water quality indicators
Fishes, green algae and diatoms are often used as water quality
indicators. Daufresne and Bo?t (2007) observed an increase related to
global warming in total abundance and in proportions of warm-water
species and size-structures changes in ?sh communities in French
rivers. Southern thermophilic ?sh species progressively replaced
northern cold water species in the upper Rh?ne River (Daufresne
et al., 2003). Furthermore, high temperature and low turbulent
diffusivities in lakes could suppress the population abundances of
green algae and diatoms ( J?hnk et al., 2008). High temperatures seem
to favor the cyanotoxins dominance, as Microcystis, over diatoms and
green algae (J?hnk et al., 2008).
2.9. Synthesis
The climate change impacts on surface water quality can be
summarized in Fig. 1, which consider the effects (droughts and ?oods)
of the two main factors (temperature and rainfalls). These impacts
depend on natural or man built environment, and the consequences
can be different according to water body type (rivers, lakes, dams,
ponds, wetlands...) and characteristics (water residence times, size,
shape, depth). For streams, the main parameters affected are DOM
and nutrients meanwhile pathogens and cyanobacteria/cyanotoxins
are more related to lakes. In between, micropollutants, inorganic or
organic are also frequently affected.
1229I. Delpla et al. / Environment International 35 (2009) 12251233
3. Expected impacts on drinking water production
Research undertaken in the 1970s, indicated the presence of
disinfection by-products (DBPs) in drinking water (Rook, 197 4;
Symons et al., 1975). Special attention was given to the concentration
of trihalomethanes (THMs) because of their potential carcinogenic
effects (Singer, 1993). The study on the occurrence of DBPs in drinking
water distribution systems has increased in the recent years, focusing
?rstly on natural organic matter transformation. Concerning emerging
DBPs linked to pharmaceuticals and new pesticides, very few studies
have been published in order to understand their formation and fate
during water treatment. For pharmaceutical by-products, most of
studies are limited to parent's pharmaceutical products (PPs) (Fent
et al., 20 06; Mompelat et al., 2009).
This part aims at reviewing the main known determinants on DBPs
formation under usual water treatment conditions. Then we consider
the expected impacts of climate change on these parameters and the
degradation of drinking water quality. Lastly, we present some further
monitoring needs for a better knowledge.
3.1. DBPs determinants
Several factors such as temperature, dissolved organic carbon
(DOC), pH, bromide concentrations, and operational factors or
chlorine doses and contact time were reported to signi?cantly affect
the formation of DBPs (Nikolaou et al., 2004; Teksoy et al., 2008).
Temperature and organic matter matrix, in?uen ced by climate
change, are considered hereafter.
Concerning the in?uence of the water temperature on the DBPs
formation, the general trend shows that for natural surface water
temperatures (530 °C), increased temperatures promote the DBPs
formation rate. Some studies (Rodriguez and Serodes, 2001) showed
that THM concentrations vary signi?cantly (from 1.5 to 2 times,
depending on the utility) between drinking water plant and tap (the
most distant). When water temperature exceeds 15 °C, spatial THM
variations are particularly high (from 2 to 4 times, depending on the
utility). In the same way, others authors reported that increasing
temperature (1033 °C) generally increased the formation of bro-
moorganic DBPs (Zhang et al., 2005). However, this general trend
should be moderated for certain unstable DBPs. Indeed, Yang et al.
(2007) studied the formation of DBPs after 3 days of chloramination
with monochloramine (NH
Cl) at three temperatures (10 °C, 20 °C
and 30 °C). They showed that chloroform formation increases with
temperature from 10 to 30 °C. However, for more unstable DBPs as
dichloroacetonitrile (DCAN) and 1,1-dichloro-2-propane (1,1-DCP),
this general trend should be moderated, since their decomposition
could increase with temperature.
In terms of water quality, it has been established that fulvic and
humic constituents of organic matter constitute important precursors
for THMs (Christman et al., 1990). Total organic carbon (TOC), as well
as UV absorbance, have been used as indicators of the presence of
organic matter in drinking water (Thomas, 2007). Some authors
pointed out that the minimum effective alum dose shows a strong
stoichiometric relationship with DOC concentrations in model waters
(Shin et al., 2008). Moreover, several studies have mentioned that
dissolved organic carbon (DOC) concentration in alum or iron treated
water was directly related to the THM formation potential (van
Leeuwen et al., 2005; Uyak and Toroz, 2007). Some research projects
based on laboratory bench-scale and ?eld data have shown that the
higher values are for these parameters, the higher the concentrations
of THMs formed (Rodriguez et al., 2000; Gol?nopoulos et al., 1998;
Garcia-Villanova et al., 1997; Montgomery, 1993). For DBPs formation,
the determinant factor could be the aromatic part or hydrophobic
fraction of NOM and molecular weight distribution (Randtke and
Jepsen, 1981; Bose and Reckhow, 1998; Croue et al., 1999; Singer,
1999). Moreover, some studies have already showed that for waters
that are not governed by sweep ?occulation, coagulant doses are
determined by the concentrations of both NOM and particles, silica
being the dominant factor for coagulant demand at high particle
concentrations (N100 mg/L) (Shin et al., 2008). Consequently,
mineral-bound humic substances increase the intrinsic complexation
properties of mineral substances for organic and inorganic pollutants
(Murphy and Zachara, 1995) and directly impact on DBPs formation
3.2. Potential impacts
Concerning climate change issues o n DBPs fo rmation, past
investigations have already observed that the occurrence of THMs in
chlorinated water may vary signi?cantly according to season and
geographical location in the distribution system (Williams et al., 1997;
Garcia-Villanova et al., 1997; Arora et al., 1997; Singer et al., 1995;
Clark, 1994). These temporal and spatial variations are due to changes
in raw and treated water quality as well as in operational parameters
(pH, chlorine dose, contact time) related to chlorination.
Rainstorm events lead to elevated levels of turbidity and organic
matter found in river waters which cause deterioration in treatment
performance. However, it has been shown that this effect is not
uniform. This could be due to a combin ation of lower water
temperatures and a change in the nature and increased concentrations
of NOM in the natural water (Hurst et al., 2004). This could also
explain why these authors observed that seasonal differences have a
signi?cant impact on process robustness, independent of the raw
water turbidity. Rodriguez and Serodes (2001) showed that when
water temperature is lower than 15 °C, THMs in treated water will not
be higher than initial THM concentration, even if these ones are high
(60 μg/L). The latter situation may be typical in spring or fall, when
the organic content of raw water and treated water tends to increase
following rain or ?eld runoff. For typical summer water temperatures
(N18 °C), the THM concentration within the system treatment may
rise from 2 to 4 times, depending on the utility (Rodriguez and
Serodes, 2001).
DOC nature and concentration are not the only parameters which
drastically change during rainstorm e vents and the biolo gical
compartment contribution should be taken into account too. Chen
and Zhang (2008) globally showed that algae contributed much more
to the HAA (haloacetic acids) formation than the THM during the
summer and autumn blooms. During these special events, when the
algal concentration is 2080 million per liter, the DBP precursors
originating from algae would account for about 20% to 50% of the total
formation potential.
Fig. 1. Impacts of climate change on water resources and drinking water quality.
1230 I. Delpla et al. / Environment International 35 (2009) 12251233
Variations of temperature, pH and aqueous composition occurring
during climate change could also have an in?uence for contaminants
on their sorption on mineral phases. When assessing the leaching
behaviour of anthropogenic compounds, the in?uence of the proper-
ties of soils has to be taken into account (Oppel et al., 2004; Yu et al.,
2009). Moreover, especially during rainfall events, mineral particles
leaching could lead to high concentrations in natural waters, having a
direct impact on coagulant demand during water treatment as seen
before (Shin et al., 2008) and on DBPs formation.
Concerning the occurrence and fate of micropollutants with
respect to drinking water treatment, the main (recent) studies are
related to pharmaceuticals. Actually, studies on pharmaceuticals are
principally linked to wastewater treatment, the ef?ciency of which
may affect the quality of water resources downstream a treated
ef?uent discharge. Even if they are pa rtially removed, residual
quantities may remain in treated water, and have been found in
drinking (tap) water (Al-Ahmad et al., 1999; Hernando et al., 2006).
The ef?ciency of pharmaceuticals removal varies with treatment
processes and also with temperature and weather (Choi et al., 2008).
For instance, diclofenac showed largely different elimination rates
between 17% (Heberer et al., 2002), 69% (Ternes et al., 1998), and 100%
(Thomas and Foster, 2004) depending on these two last parameters.
Finally, for pesticides elimination in conventional physi-cochemical
drinking water treatment processes, such as ?occulation, sedimenta-
tion, ?ltration, or lime softening, only certain lipophilic substances are
removed adequately (Baldauf, 2006).
Natural micropollutants, mainly represented by cyanotoxins may
also have a huge impact on drinking water treatment. Chlorination,
micro-/ultra?ltration and especially ozonation are the most effective
water treatment procedures in destroying cyanobacteria and in
removing microcystins (Hitzfeld et al., 2000). During cyanobacterial
bloom events, ozonation may be an appropriate process to eliminate
peptide toxins like microcystin-LA and-LR (Rositano et al., 1998, 2001;
Brooke et al., 2006). Lots of studies concerning removal of cyano-
bacterial toxins from water showed that the effectiveness of the
oxidation process is not only dependant on the reactant concentration,
but also on temperature, pH, ionic composition (Rositano et al., 1998;
Shawwa and Smith, 2001) and NOM concentration (Al Momani et al.,
2008). Although very few studies reported the relationship between
algae and DBPs precursors, some authors pointed out the algal
contribution to some DPBs formation (Chen and Zhang, 2008). Some
studies tried to improve new by-products identi?cation for cyanotox-
ins ( Rodriguez et al., 2007; Merel et al., 2009). However, DBPs
formation has largely not been investigated.
3.3. Monitoring and modeling of impacts
Face to the previous expected impacts on the degradation of
(drinking) water quality, several monitoring tools are proposed.
The ?rst way is to incorporate on-line TOC (or DOC) measurements
into coagulation control algorithm for pH control and coagulant dose
to prevent uncontrolled variation especially during storm/raining
events (Hurst et al., 2004). In the same area, the development of ?eld
monitoring procedures or system may be useful for improving DOM
knowledge in order to evaluate bulk properties mainly in?uencing
disinfection by products formation such as biological activities (algal
contribution, photosynthetic evolution) or molecular polarity.
Fluorescence analysis could help in the assessment of DOM sources
by spectral signatures related to waters affected by microbial activity,
either by wastewater in?uence or by autochthonous processes and
could correlate some of these data with DOC for instance (Parlanti
et al., 20 00; Jung et al., 2005; Rosario-Ortiz et al., 2007).
Another solution is the prediction of the occurrence or fate of some
physico-chemical parameters through modeling. Uyak and Toroz
(2007) have proposed a model for the concentration estimation of
THM and HAA in chlorinated raw water of surface water supplies for
instance. Other models have already been developed that relate
coagulant dose to the concentration and character of organics present
in natural waters. These models enable prediction of inorganic
coagulant doses that maximize removal of organics at a particular
coagulation pH (van Leeuwen et al., 2005). As we have seen before,
model development studies taking into account temperature should
be continued. The complexity of DBP formation reactions makes it
dif?cult to develop universally applicable models. This research ?eld
should however be considered with special attention for the future.
A last point to consider is the analytical development for emerging
substances and by-products. Concerning pharmaceuticals and pesti-
cides, there is a real need for identi?cation and toxicity assessment on
the degradation byproducts formed during water treatment. The
removal of pharmaceuticals and other polar micro-pollutants can only
be assured using advanced techniques such as ozonation, activated
carbon or membrane ?ltration (Ternes et al., 2002) or eventually UV
treatment (Canonica et al., 2008). However, developing only the best
available treatment techniques to remove these substances without
taking into account DBPs formation is not the actual challenge.
Comparison on emerging substances consumption (such as pharma-
ceuticals) and occurrence in water based on a reference methodology,
health and ecotoxicological risk assessments should be developed in
parallel with analytical methods permitting identi?cation and quan-
ti?cation of by-products.
3.4. Synthesis
The climate change impacts on drinking water treatment issues
can be summarized in Fig. 2. Remind that climate change may cause at
the resource level (surface water), huge hydrologic variations, water
temperature rise and increases of pollution load (chemical and
microbiological). For treatment plants, considering that all remedia-
tion actions have been made (pollution source reduction, run off
limitation, fertilizers and pesticides reduction management, etc.),
adaptation measures must be envisaged for a better ef?ciency,
particularly with regards to extreme events (heavy rainfalls and
droughts). These measures integrate complementary treatment steps
and process control even for small water supply systems. Moreover,
water quality monitoring with analysis of micropollutants among
which emerging substances and treatment by products must be carry
out, as well as health risk assessment (following the water safety plan
procedure). Obviously, in case of severe ?oods, transportation of
bottles or tanks may be the only solution for safe drinking water
Fig. 2. Climate change impacts and drinking water treatment issues.
1231I. Delpla et al. / Environment International 35 (2009) 12251233
4. Conclusion
The main outcome of this literature review on climate change impact
on surface water quality (from resources to tap) is that there is a
degradation trend of drinking water quality leading to an increase of at
risk situations with regard to potential health impact, mainly during
extreme meteorological events. Among water quality parameters,
dissolved organic matter, micropollutants and pathogens are susceptible
to rise in concentration or number as a consequence of temperature
increase (water, air and soil) and heavy rain falls in temperate countries.
Another conclusion is the lack of information on micropollutants
occurrence and fate with regard to climate change impacts and
treatment ef?ciency, including potentially association and transporta-
tion with natural organic matter. Disinfection by products of
micropollutants not removed during treatment and of residues must
be identi?ed and their toxicity assessed. Last conclusion concerns
water borne diseases potentially highly linked to climate change
impacts but still rarely studied at least for temperate countries. Finally,
there is a huge need for water quality monitoring and predictive tools
as models and decision support systems mainly with the aim of health
risks assessment and remediation and adaptation actions.
The authors would like to thank Sophie Mompelat and Sylvain
Merel, PhD students of the Laboratoire d'Etude et de Recherche en
Environnement et Santé (LERES), for their fruitful discussions on
cyanotoxins and pharmaceuticals occurrence and persistence in the
environment. They also thank André Lavoie from Sherbrooke
University for his help as well as the reviewers of the manuscript,
suggesting us very relevant improvements.
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... Lakes are crucial supplies of drinking and household water for millions of people worldwide (Delpla et al., 2009;Qin et al., 2010). However, the quality, quantity and availability of these resources are threatened for various reasons. ...
... Climate change is predicted to increase temporal and regional variation in precipitation, causing regional scarcity (or increase) of water resources for industry, agriculture and households (Bangash et al., 2013;Donnelly et al., 2017). The quality and quantity of water supplies for human use are already being harmed by climate change, pollution, eutrophication and overuse of lake water for agricultural irrigation (Delpla et al., 2009;Whitehead et al., 2009;Qin et al., 2010;Rodell et al., 2018). Poor water quality increases the costs of water treatment and may even prevent the use of water by humans (Pretty et al., 2003;Qin et al., 2010). ...
The Anthropocene presents formidable threats to freshwater ecosystems. Lakes are especially vulnerable and important at the same time. They cover only a small area worldwide but harbour high levels of biodiversity and contribute disproportionately to ecosystem services. Lakes differ with respect to their general type (e.g. land‐locked, drainage, floodplain and large lakes) and position in the landscape (e.g. highland versus lowland lakes), which contribute to the dynamics of these systems. Lakes should be generally viewed as ‘meta‐systems’, whereby biodiversity is strongly affected by species dispersal, and ecosystem dynamics are contributed by the flow of matter and substances among locations in a broader waterscape context. Lake connectivity in the waterscape and position in the landscape determine the degree to which a lake is prone to invasion by non‐native species and accumulation of harmful substances. Highly connected lakes low in the landscape accumulate nutrients and pollutants originating from ecosystems higher in the landscape. The monitoring and restoration of lake biodiversity and ecosystem services should consider the fact that a high degree of dynamism is present at local, regional and global scales. However, local and regional monitoring may be plagued by the unpredictability of ecological phenomena, hindering adaptive management of lakes. Although monitoring data are increasingly becoming available to study responses of lakes to global change, we still lack suitable integration of models for entire waterscapes. Research across disciplinary boundaries is needed to address the challenges that lakes face in the Anthropocene because they may play an increasingly important role in harbouring unique aquatic biota as well as providing ecosystem goods and services in the future.
... In the future, it is also expected that ensuring water needs for drinking, industrial, agricultural and other uses will be one of the most important challenges for societies. Already, this has been a problem in some part of the world [1] partly because of climate change [2], [3]. Emergencies, such as the Covid-19 pandemic [4] can compound the pressure on water usage and availability that are already under pressure from climate change in some parts of the world. ...
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The COVID-19 Pandemic affects not only people from all over the world but also the environment and natural resources. Although hygiene and disinfection are the best ways that protect people from COVID-19, they have serious consequences (higher demand for water and water shortages) on water usage and resources under the impacts of climate change.
... Global increases in the frequency, severity and duration of extreme weather events may alter water quality and pose challenges to water quality managers (Khan et al., 2015). Extreme weather events, including heavy rainfalls and floods, intense storms, heatwaves and droughts, are reported to have potential impacts on surface water, groundwater and drinking water quality (Delpla et al., 2009;Whitehead et al., 2009). Recent studies have focused on the impact of extreme weather events on physico-chemical water quality parameters (e.g. ...
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Extreme weather events induced by climate change have potential to impact water quality and have received increasing attention from surface water source management perspectives. However, it remains unclear how such phenomenon may influence concentration of emerging contaminants (ECs) in surface water that are vital source of irrigation. In the present study, we investigated the impact of high precipitation and ambient temperature on the distribution of ECs in surface water samples (N=250) from Mid-Atlantic region, collected between 2016 and 2018. We analyzed the water samples using a liquid chromatography tandem mass spectrometry (LC-MS/MS) based method. We then investigated how the detection frequencies and concentrations of ten emerging contaminants were influenced by high precipitation and temperature events in the previous day or 7 days prior to the sampling events using a generalized additive model (GAM). We observed that heavy rainfalls occurring within 24 hr before sampling increased the concentration/likelihood of detection of the ECs in surface waters, likely due to surface runoffs, remobilization from soil/sediment and sewage overflows. The impact of high precipitation during previous seven days varied across chemicals. Likewise, the detection frequency and concentration of most analytes increased with increasing temperature, in previous day of sampling event, likely due to enhanced solubility in water. Long-term high temperature events appeared to decrease the detection of the most tested ECs probably due to enhanced degradation. However, the potential risk of unknown degradation products cannot be ignored. Our results indicate potential decline of water quality after extreme weather events which may have implications for water source management under changing climate.
... W skali globalnej wyra?ny trend dodatni w ci?gu ostatnich kilku dekad w odniesieniu do temperatury wód ?ródl?dowych wykazali Webb i Nobilis (2007), Delpla i in. (2009), Kaushal i in. (2010), van Vliet i in. (2011) oraz O'Reilly i in. (2015. Wzrost temperatury wód (o 1-3°C) w ci?gu ostatniego stulecia zaobserwowano równie? w rzekach europejskich (Raport 2012, Dokulil 2014, Hannah, Garner 2015, Wollway i in. 2017. Tendencj? do wzrostu temperatury wód rzecznych w Polsce, zw?aszcza w ostatnich kilku dekad ...
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Zró?nicowanie czasowo-przestrzenne tendencji zmian termiki wód rzecznych w Polsce Zarys tre?ci: Celem pracy by?o okre?lenie trendu oraz kierunku zmian temperatury wód rzecznych w Polsce w latach 1971-2015. Analiz? obj?to 44 rzeki o quasi-naturalnym re-?imie termicznym. Trendy i zmiany temperatury ?redniej miesi?cznej, rocznej, sezonowej oraz minimalnej i maksymalnej ustalono, stosuj?c metod? regresji liniowej. W wi?kszo?ci serii pomiarowych stwierdzono pozytywne trendy temperatury w badanym okresie. Najwi?ksz? liczb? posterunków (ok. 80%) z dodatnim i istotnym statystycznie trendem temperatury zidentyfikowano w lipcu, natomiast najwi?kszy wzrost temperatury wyst?pi? w listopadzie i wynosi? w ró?nych cz??ciach Polski od 0,3°C?dec-1 do 0,6°C?dec-1. Sytu-acja ta dotyczy?a przede wszystkim górnego i ?rodkowego odcinka Wis?y oraz jej górskich dop?ywów. Wykazano równie? przestrzenne zró?nicowanie maksymalnych rocznych tem-peratur wód rzecznych, które wynios?o na Wi?le i jej dop?ywach od 0,2°C?dec-1 do ponad 0,8°C?dec-1 , a na Odrze i rzekach Przymorza od 0,1°C?dec-1 do 0,3°C?dec-1. Najmniejsze zmiany temperatury zaobserwowano w miesi?cach pó?rocza zimowego od grudnia do marca, a istotne, dodatnie trendy stwierdzono jedynie na 7-23% badanych rzek. Zaobser-wowane zmiany temperatury wody zwi?zane by?y z pozytywnymi trendami temperatury powietrza. Wyniki badań mog? przyczyni? si? do poszerzenia informacji w zakresie sezo-nowych i wieloletnich trendów zmian temperatury wód, co jest istotne dla oceny stabilno-?ci termicznej ekosystemów wodnych i ich optymalnego zarz?dzania.
... The impact of climate change upon hydrological regimes and water quality has become a major issue, raising the need of adequate tools to detect both the existence and magnitude of changes (Delpla et al. 2009;Bl?schl et al. 2017Bl?schl et al. , 2019. Climate change does not only affect the magnitude and frequency of floods but also water quality, biodiversity, and landscape and human activities (Schmutz & Sendzimir 2018). ...
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The impact of climate change upon the hydrological regimes of streams has become an issue of major concern that requires adapted tools to detect and follow the scale of possible changes. In this study, we use a geochem-ical approach that exclusively relies on measurements of chemical concentrations in order to investigate the effect of climate change on the hydrological regime of the River Arve, a Franco-Swiss river running from the Alps to the River Rhone. Our method relies on the use of a dimensionless parameter, the ratio of uranium and barium concentrations in river waters. This marker has the advantage of not needing the measurement of river discharges. Its application to 25 years of data collected in River Arve by Canton Geneva, Switzerland, allows to conclude that the glacio-nival signature is appearing earlier in the year and lasts for longer periods.
... Further, we have observed a decrease in the area under floating gardens of the Dal Lake being negatively correlated with the increase in the average COD, NO 3 -N, and TP of the lake. Vanni et al. (2001), Guo et al. (2002), and Delpla et al. (2009) have shown that the vegetation within the water bodies assimilate nitrates and phosphates as fertilizers, and thus, decrease in the area of vegetation shall lead to increase in the concentrations of these nutrients that enter into the lake system through various sources. Similarly, floating gardens, which are the vegetation patches inside the Dal Lake, helped in the assimilation of nitrates and phosphates from the lake, thereby helping in decreasing their concentration in the lake. ...
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A dynamic process like land use, if anthropogenically unsustainable, adversely affects the well-being of the land system. Worldwide, water bodies are facing imminent threat due to unsustainable anthropogenic activities. Water quality and ecology are the two characteristics of water bodies, if not preserved, shall have a direct consequence on the well-being of the human systems. Hence it is essential to understand the causes and consequences of the deteriorating water body systems. The condition is particularly grim in Himalayan water body ecosystems, where unplanned and unchecked urbanization has threatened their very existence. In the present study, the dynamics of land use/land cover (LULC) and its impact on the water quality of Dal Lake in Kashmir Himalaya, India has been assessed. We carried out a detailed study wherein changing LULC is analyzed against the deteriorating trophic status of the Dal Lake using time-series of satellite imagery of the lake's catchment and its water quality data. Results indicated that the water quality of Dal Lake has remarkably deteriorated due to increased nutrient and sediment loads from the catchment, attributed to significant anthropogenic activities in the catchment. Due to unprecedented LULC changes in the catchment, the forest class shows a significantly negative change since the last four decades (1980-2018), corroborating with the ongoing deterioration of physicochemical characteristics of the lake. The analysis shows an increase in all the agents of eutrophication, such as NO 3-N, TP, and COD, from 1990 to 2018. The decrease in forest, agriculture, and floating gardens was observed to show a significant negative correlation with the increase in the decadal average values of the COD, NO 3-N, and TP for the same corresponding period. Similarly, a positive correlation was found between the increase in built-up, aquatic vegetation, bare surfaces, and these water quality parameters, establishing a strong relationship between the deteriorating condition of the lake and changing LULC. Our findings indicate that changing LULC of the lake's catchment is one of the critical factors that has significantly contributed toward the deteriorating ecology and water quality of the Dal Lake. This study shall contribute toward the development of the robust conservation strategy in order to save this urban lake from its untimely death.
... Besides climate change impacts on water availability and hydrological risks, there are also consequences on water quality. For example, floods and droughts will also modify water quality by direct effects of dilution or concentration of dissolved substances (Delpla et al. 2009), and changes in precipitation, wind speed, incoming solar radiation, and air temperature directly influence river water quality by altering changes in stream flow and river water temperatures (Rehana and Mujumdar 2012). Climate change is likely to impact more severely on the poorer people of the world, because they are more exposed to the weather, closer to the biophysical and experience limits of climate, and their adaptive capacity is lower (Tol et al. 2004). ...
... No significant correlation was found between temperature and water quality. Some studies had pointed out that higher temperature may lead to temperature stratification in the water, which could promote the release of pollutants from bottom sediment into the water [48,49]. In addition, temperature is also an important factor in eutrophication [50]. ...
... No significant correlation was found between temperature and water quality. Some studies had pointed out that higher temperature may lead to temperature stratification in the water, which could promote the release of pollutants from bottom sediment into the water [48,49]. In addition, temperature is also an important factor in eutrophication [50]. ...
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Xuzhou is the hub city of the east route of China's South-to-North Water Diversion (SNWD) project and implemented dozens of measures to ensure the water quality security of the water transmission line. In order to detect the effectiveness of water quality improvement measures, the monthly water quality data of five water quality parameters from 2005 to 2015 of six state-controlled monitoring sites in Xuzhou section were selected for analysis. The results showed that the water quality improved from 2.95 in 2005 to 2.74 in 2015, as assessed by the comprehensive water quality identification index (CWQII), and basically reached the Class III standards of China's Environmental Quality Standard for Surface Water (GB3838-2002) from 2011 to 2015. The trend analysis showed that the decline of ammonia nitrogen (NH 3-N) was the most obvious among the five water quality parameters. However, the concentrations of phosphorus (TP) showed significant upward trends at three sites. The positive abrupt change of time series of water quality occurred in 2009-2011. The identification of influencing factors of water quality changes by multivariate statistical methods found that the urbanization factor accompanied by a decrease in agricultural nonpoint source pollution emissions and the enhancement of wastewater treatment capacity, the closure of factories with substandard emissions and precipitation were the major influencing factors of most water quality parameters, which confirmed the effectiveness of measures for water quality improvement in Xuzhou.
... The character and composition of natural organic matter (NOM) in freshwater ecosystems also appears to respond to variations in climatic conditions (Hejzlar et al. 2003;Delpla et al. 2009;Zhu et al. 2017;Gavin et al. 2018;Parr et al. 2019). This trend is also observed in Australian catchments with deleterious consequences for the performance of existing treatment infrastructure on more highly variable potable water supplies (Mohiuddin et al. 2014). ...
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The present understanding of how changes in climate conditions will impact the flux of natural organic matter (NOM) from the terrestrial to aquatic environments and thus aquatic dissolved organic carbon (DOC) concentrations is limited. In this study, three machine learning algorithms were used to predict variations in DOC concentrations in an Australian drinking water catchment as a function of climate, catchment and physical water quality data. Four independent variables including precipitation, temperature, leaf area index and turbidity (n = 5,540) were selected from a large dataset to develop and train each machine learning model. The accuracy of the multivariable linear regression, support vector regression (SVR) and Gaussian process regression algorithms with different kernel functions was determined using adjusted R-squared (adj. R2), root-mean-squared error (RMSE) and mean absolute error (MAE). Model accuracy was very sensitive to the time interval used to average climate observations prior to pairing with DOC observations. The SVR model with a quadratic kernel function and a 12-day time interval between climate and water quality observations outperformed the other machine learning algorithms (adj. R2 = 0.71, RMSE = 1.9, MAE = 1.35). The area under the receiver operating characteristic curve method (AUC) confirmed that the SVR model could predict 92% of the elevated DOC observations; however, it was not possible to estimate DOC values at specific sampling sites in the catchment, probably due to the complex local geological and hydrological changes in the sites that directly surround and feed each sampling point. Further research is required to establish potential relationships between climatological data and NOM concentration in other water catchments – especially in the face of a changing climate.
Literature Review
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Cyanobacteria (blue-green algae) produce toxins that may present a hazard for drinking water safety. These toxins (microcystins, nodularins, saxitoxins, anatoxin-a, anatoxin-a(s), cylindrospermopsin) are structurally diverse and their effects range from liver damage, including liver cancer, to neurotoxicity. The occurrence of cyanobacteria and their toxins in water bodies used for the production of drinking water poses a technical challenge for water utility managers. With respect to their removal in water treatment procedures, of the more than 60 microcystin congeners, microcystin-LR (L, L-leucine; R, L-arginine) is the best studied cyanobacterial toxin, whereas information for the other toxins is largely lacking. In response to the growing concern about nonlethal acute and chronic effects of microcystins, the World Health Organization has recently set a new provisional guideline value for microcystin-LR of 1.0 mu g/L drinking water. This will lead to further efforts by water suppliers to develop effective treatment procedures to remove these toxins. Of the water treatment procedures discussed in this review, chlorination, possibly micro/ultrafiltration, but especially ozonation are the most effective in destroying cyanobacteria and in removing microcystins. However, these treatments may nor be sufficient during bloom situations or when a high organic load is present, and toxin levels should therefore be monitored during the water treatment process. In order to perform an adequate human risk assessment of microcystin exposure via drinking water, the issue of water treatment byproducts will have to be addressed in the future.
Technical Report
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There is increasing interest in the United States in trying to understand the factors that influence the deterioration of water quality between treatment and consumption. The application of water quality propagation models for distributed drinking water can provide insight into identifying these factors. An overview of the application of water quality models to distributed drinking water illustrates the usefulness of this technique.
The effect of the different teatment stages of a lake waterworks on lindane-containing raw water is investigated on a semi-full scale. It is found that neither ozone nor a rapid sand filter is able to break down or retain lindane to any appreciable extent. There is no significant difference in this respect between a filter laden with suspended matter and one which is freshly flushed. Activated carbon shows itself to be the most suitable means of protecting the consumer from poison-carrying drinking water. The investigation shows that the different types of carbon have different adsorption properties.
UV-Visible Spectrophotometry of Water and Wastewater, Second Edition, represents an update to the first book dedicated to the use of UV spectrophotometry for water and wastewater quality monitoring. Using practical examples, the book illustrates how this technique can be a source of new methods of characterization and measurement. Easy and fast to run, this simple and robust analytical technique must be considered as one of the best ways to obtain a quantitative estimation of specific or aggregate parameters (e.g., Nitrate, TOC) and simultaneously qualitative information on the global composition of water and its variation. This second edition presents the current methods and applications for water quality monitoring based on UV spectra, including the most recent works and developments. After the introduction of the basics for UV spectrophotometry understanding, the applications of UV measurement are presented, both from the family of chemicals and water quality parameters and from the type of water. Writing from years of experience in the development and applications of UV systems and from scientific and technical works, the authors provide several useful examples showing the great interest of UV spectrophotometry for water quality monitoring. At the end of the book, the UV spectra library of the first edition is updated with dozens of new chemicals of interest. Adds dozens of new chemicals of interest to the first library of UV-spectra dedicated to water, providing data readily available for researchers and users Includes new sections on data integrity and security, UV estimation of classes of compounds, UV and turbidity, drinking water, pollution tracking, high frequency monitoring, disinfection by products assessment, pesticides, pharmaceuticals, and more Provides a theoretical basis for further research in the field of spectra exploitation Contains helpful practical applications of this quick, simple, and inexpensive technique.
Compliance with the proposed D/DBP Rule may be dictated to a much more significant degree by haloacetic acids than by THMs.
Over the last few years, the presence of chlorination by-products (CBP) in drinking water has become an issue of particular concern for utility managers. As regulations about CBP (in particular trihalomethanes - THM), are becoming more strict, water utilities will have to adjust their operation strategies to comply with new standards while maintaining a residual chlorine which ensures an acceptable microbiological quality. Complying with stricter THM standards is particularly difficult for utilities which use surface raw water and practice chlorination as the unique treatment process. In this paper, the authors explore the usefulness of predictive models as decision-making tools for drinking water managers in dealing with the THM issue. In the first part of the paper, the process of developing models of THM formation in chlorinated surface waters using two different sources of data (from bench-scale and from field-scale studies) is described. The second part of the paper focuses on the application of such models to the analysis of the feasibility of updating THM regulations in the province of Quebec (Canada). Simulations allow the estimation of the percentage of utilities, currently using chlorination as the unique treatment, which would have to upgrade treatment to comply with a new THM standard.
After the EPA disclosed its findings of organic chemicals in New Orleans water, it was decided to conduct another, more inclusive study, with 80 specific sites throughout the U.S. designated as test areas. The main objectives of the National Organics Reconnaissance Survey (NORS) are described, and procedural techniques are explained for: engineering evaluation of treatment facilities; sampling for trihalomethanes, carbon tetrachloride and 1,2 dichloroethane; analytic methods for chloroform, bromodichloromethane, dibromochloromethane, bromoform, carbon tetrachloride and 1,2 dichloroethane; confirmation analysis; and analytical methods for general organic parameters. Water quality data for the 80 cities tested are presented and the results are discussed in terms of the occurrence of organics, 1,2 dichloroethane and carbon tetrachloride, nonvolatile total organic carbon, and influence of source type and treatment practice on trihalomethane formation. Consideration is also given to the use of alternate indicators of organic contaminant levels and the overall significance of the findings.
Pharmaceuticals are a class of chemicals whose fate in the environment has received increasing attention in the past few years. A quantitative method was developed for the determination of acidic pharmaceuticals (ibuprofen, naproxen, ketoprofen, mefenamic acid, and diclofenac), caffeine and the antibacterial triclosan in wastewater effluent. The compounds were extracted from wastewater samples on Waters Oasis HLB solid-phase extraction columns, derivatized with N,O-bis [Trimethylsilyl] trifluoroacetamide (BSTFA) and analyzed using gas chromatography-mass spectrometry. Estimated method detection limits ranged from 6 to 45 ng/L based on replicate analyses (n = 10). This method was applied to the analysis of effluent from a wastewater treatment plant and compounds were detected at concentrations of 18-72 ng/L.