Ianis Delpla

Impacts of rainfall events on runoff water quality in an agricultural environment in temperate areas

Since a rise in dissolved organic carbon (DOC) concentrations has been observed for surface waters at least over the last two decades, a change in weather conditions (temperature and precipitations) has been proposed to partly explain this increase. While the majority of DOC delivery from soils to stream occurs during rainfall events, a better understanding of the rainfall influence on DOC release is needed. This study has been conducted in Brittany, western France, on agricultural experimental plots receiving either cattle manure (CM) or pig slurry (PS) as fertilizers in accordance with local practices. Each plot was instrumented with a flow meter and an auto sampler for runoff measurements. The results show that export of DOC during high intensity events is higher than during lower intensity rainfalls. Fertilization has a noticeable impact on total organic carbon (TOC) fluxes with an increase of five to seven folds for PS and CM respectively. If TOC shock load occurs shortly after the rainfall peak, DOC maximum appears with the first flush of the event. Organic carbon (OC) is mainly under colloidal (41.2%) and soluble (23.9%) forms during the first stage of a rainfall event and a control of rainfall intensity on OC colloidal transport is suggested. These findings highlight the potential risk of receiving water quality degradation due to the increase of heavier rainfall events with climate change in temperate areas.

Effects of future climate and land use scenarios on riverine source water quality.

Surface water quality is particularly sensitive to land use practices and climatic events that affect its catchment. The relative influence of a set of watershed characteristics (climate, land use, morphology and pedology) and climatic variables on two key water quality parameters (turbidity and fecal coliforms (FC)) was examined in 24 eastern Canadian catchments at various spatial scales (1 km, 5 km, 10 km and the entire catchment). A regression analysis revealed that the entire catchment was a better predictor of water quality. Based on this information, linear mixed effect models for predicting turbidity and FC levels were developed. A set of land use and climate scenarios was considered and applied within the water quality models. Four land use scenarios (no change, same rate of variation, optimistic and pessimistic) and three climate change scenarios (B1, A1B and A2) were tested and variations for the near future (2025) were assessed and compared to the reference period (2000). Climate change impacts on water quality remained low annually for this time horizon (turbidity: +1.5%, FC: +1.6%, A2 scenario). On the other hand, the influence of land use changes appeared to predominate. Significant benefits for both parameters could be expected following the optimistic scenario (turbidity: -16.4%, FC: -6.3%; p < 0.05). However, pessimistic land use scenario led to significant increases on an annual basis (turbidity: +11.6%, FC: +15.2%; p < 0.05). Additional simulations conducted for the late 21st century (2090) revealed that climate change impacts could become equivalent to those modeled for land use for this horizon.

Monitoring of methotrexate chlorination in water

Anti-cancer drugs are an important class of pharmaceutical products. Methotrexate (MTX) is a folic acid antagonist used in high doses as antimetabolite in anti-cancer treatment as well as in low doses for the treatment of rheumatoid arthritis and adults psoriasis. In the past, several anti-cancer drugs, including methotrexate, have been found in the environment. Their presence in water, especially if used for the production of drinking water, is even in low concentrations of particular interest, due to the risk to retrieve them in the consumed water and their high activity and grave effects. But prior to usage as drinking water, raw waters are treated and chlorination is a common practice in several countries. As such a treatment can lead to the formation of organochlorine in water, the study of the fate of MTX during chlorination in a batch trial was carried out. The reaction was monitored by dissolved organic carbon (DOC) and by fluorescence and UV spectroscopy. Investigation of by-products formed was done with liquid chromatography/mass spectrometry (LC/MS). Under the given experimental conditions, Methotrexate was eliminated rapidly (t1/2 around 21xa0min). However, DOC elimination was incomplete. Monitoring with LC-MS showed the formation of a monochlorinated transformation product of MTX. In silico analysis of the proposed transformation products for different carcinogenic, mutagenic and genotoxic endpoints with different software platforms provided no clear evidence that the possible transformation products after chlorination might be more toxic than the parent compound. However, since a number of alerts is altered after chlorination, it cannot be excluded that the toxicity of these transformation products might be modulated compared with the parent compound.

Investigating social inequalities in exposure to drinking water contaminants in rural areas

Few studies have assessed social inequalities in exposure to drinking water contaminants. This study explores this issue in 593 rural municipalities of Québec, Canada. Quartiles of an ecological composite deprivation index were used as a proxy of socioeconomic status. Total trihalomethanes (TTHMs) and lead were chosen as proxies of chemical drinking water quality. The results show that the majority of deprived rural municipalities apply no treatment to their water (26%) or use a basic treatment (51%), whereas a relative majority of the wealthiest municipalities (40%) use advanced treatment. The proportion of municipalities having important lead (>5xa0μg/L) levels is highest in most deprived municipalities. Moreover, most deprived municipalities have a higher risk of high tap lead levels (RRxa0=xa01.33; 95%CI: 1.30, 1.36). Conversely, most deprived municipalities have a lower risk of high TTHMs levels (RRxa0=xa00.78; 95%CI: 0.69, 0.86). These findings suggest an environmental inequality in drinking water contaminants distribution in rural municipalities.

A Decision Support System for Drinking Water Production Integrating Health Risks Assessment

The issue of drinking water quality compliance in small and medium scale water services is of paramount importance in relation to the 98/83/CE European Drinking Water Directive (DWD). Additionally, concerns are being expressed over the implementation of the DWD with respect to possible impacts on water quality from forecast changes in European climate with global warming and further anticipated reductions in north European acid emissions. Consequently, we have developed a decision support system (DSS) named ARTEM-WQ (AwaReness Tool for the Evaluation and Mitigation of drinking Water Quality issues resulting from environmental changes) to support decision making by small and medium plant operators and other water stakeholders. ARTEM-WQ is based on a sequential risk analysis approach that includes consideration of catchment characteristics, climatic conditions and treatment operations. It provides a holistic evaluation of the water system, while also assessing human health risks of organic contaminants potentially present in treated waters (steroids, pharmaceuticals, pesticides, bisphenol-a, polychlorobiphenyls, polycyclic aromatic hydrocarbons, petrochemical hydrocarbons and disinfection by-products; n = 109). Moreover, the system provides recommendations for improvement while supporting decision making in its widest context. The tool has been tested on various European catchments and shows a promising potential to inform water managers of risks and appropriate mitigative actions. Further improvements should include toxicological knowledge advancement, environmental background pollutant concentrations and the assessment of the impact of distribution systems on water quality variation.

Experimental disinfection by-product formation potential following rainfall events.

Spring rainfall events can have deleterious impacts on raw and drinking water quality for water treatment plants that use surface waters. This study compares the influence of land use and climate on DBP precursors in two catchments supplying the region around the City of Québec, Canada, and assesses the variability of Disinfection By-Product (DBP) concentration and speciation following rainfall events. DBPs (trihalomethanes (THMs) and haloacetic acids (HAAs)) and their precursors in raw waters (pH, turbidity, specific ultraviolet absorbance (SUVA), total and dissolved organic carbon, bromides and chlorine dose) were monitored. Various experimental chlorination tests, DBP formation potential (DBPFP) and Simulated Distribution Systems (SDS), were also performed. Differences in pre-rainfall (baseflow) water quality were noted according to the different watershed land uses. Raw water quality patterns showed modifications between baseflow and rainfall periods, with a degradation of raw water quality according to turbidity and SUVA in both water sources. Rainfall events were also shown to alter organic matter reactivity with an increase in THM formation potential for both sites. A less noticeable impact on HAA formation potential was observed. However, no clear differences in DBPFP tests were observed between the sites. SDS tests showed that rainfall events lead to considerable rises in organic carbon reactivity of filtered waters, even after primary treatment, with a 2-fold increase in THM and HAA concentrations following rainfall for waters representing the end of one main distribution system (20xa0h contact time). These increases are linked mainly to a rise in non-brominated DBPs such as chloroform, trichloroacetic acid and dichloroacetic acid. This study confirms the importance of strictly controlling OM levels during drinking water treatment to ensure safe drinking water quality throughout the distribution system.

Variability of disinfection by-products at a full-scale treatment plant following rainfall events

The quality of drinking water sources can decrease when contaminants are transported by overland and subsurface flow and discharged into surface waters following rainfall events. Increases in organic contaminants such as road salts and organic matter may occur and potentially modify disinfection by-products (DBPs) concentration and speciation. This study investigated the effects of various spring rainfall events on the quality of treated waters at a large water treatment plant through the implementation of intensive water quality monitoring of raw, filtered and treated waters during different rainfall events. DBPs (four trihalomethanes and six haloacetic acids) and their explanatory variables (pH, turbidity, water temperature, specific ultraviolet absorbance, total and dissolved organic carbon, bromide and chlorine dose) were measured during four rainfall events. The results showed that water quality degrades during and following rainfall, leading to small increases in trihalomethanes (THM4) and haloacetic acids (HAA6) in treated waters. While THM4 and HAA6 levels remained low during the pre-rainfall period (<9xa0μg/L) for the four sampling campaigns, small increases in THM4 and HAA6 during and after spring rainfall events were observed. During the rainfall and post-rainfall periods, concentration peaks corresponding to 3-fold and 2-fold increases (respectively 27.5xa0μg/L for THM4 and 12.6xa0μg/L for HAA6) compared to pre-rainfall levels were also measured. A slight decrease in harmful brominated THM and HAA proportion was also observed following rainfall events.

Impact of Raw Water Quality and Climate Factors on the Variability of Drinking Water Quality in Small Systems

Drinking water quality is mainly influenced by the variable quality of source water, which is affected by both meteorological and climate factors. Contrary to medium and large municipalities, small systems do not have appropriate equipment to face important variations of raw water quality, and they do not have enough information either on the impact of these alterations. The objective of this study is to develop a decision-making tool to small system operators allowing the determination of risk periods, based on easily accessible measures. The impact of several raw water quality parameters and climate factors on drinking water quality was under study. A stepwise regression analysis was applied to determine the most important factors. Two of them were retained: the level of UV254 of raw water and average maximal air temperature of 15xa0days before measurement. These factors are representative of raw water quality or meteorological conditions and are easily accessible to systems with restricted financial capacities. A logistic regression analysis contributed to the estimation of the probability to provide drinking water of bad quality (defined by a drinking water quality index). Finally, results of the analysis were synthetized in a visual tool, allowing the identification of risk periods using the known values of UV254 and average maximal air temperature of 15xa0days. This tool may strongly contribute to the improvement of drinking water management in small systems, as it provides easily accessible information on the risks of deterioration of drinking water quality using two simple parameters.

Drinking Water Source Monitoring Using Early Warning Systems Based on Data Mining Techniques

Improving drinking water source monitoring is crucial for efficiently managing the drinking water treatment process and ensuring the delivery of safe water. Data mining techniques could prove useful to help forecast source water quality. In this study, two approaches were used to forecast turbidity mean levels and peaks in the main drinking water source of the city of Québec, Canada. Trend analysis was applied for the prediction of significant turbidity events (>99th percentile of data distribution). Artificial neural networks using antecedent moisture conditions as input parameters (all turbidity peaks) served to forecast daily turbidity time series. Results show that trend analyses help anticipate the timing of turbidity peaks ― with differences between the cold season (fall and winter) and the warm season (spring and summer) and mean anticipations between 45 and 85xa0min and 25 and 45xa0min, respectively ― and the magnitude of the peak. The artificial neural network model was developed and proven capable of predicting the mean levels of turbidity at the drinking water intake of the investigated catchment. These early warning systems could be applied to source water system forecasting and provide a framework for adjusting drinking water treatment operations.

Heterogeneity in the Relationship between Disinfection By-Products in Drinking Water and Cancer: A Systematic Review

The epidemiological evidence demonstrating the effect of disinfection by-products (DBPs) from drinking water on colon and rectal cancers is well documented. However, no systematic assessment has been conducted to assess the potential effect measure modification (EMM) in the relationship between DBPs and cancer. The objective of this paper is to conduct a systematic literature review to determine the extent to which EMM has been assessed in the relationship between DBPs in drinking water in past epidemiological studies. Selected articles (n = 19) were reviewed, and effect estimates and covariates that could have been used in an EMM assessment were gathered. Approximately half of the studies assess EMM (n = 10), but the majority of studies only estimate it relative to sex subgroups (n = 6 for bladder cancer and n = 2 both for rectal and colon cancers). Although EMM is rarely assessed, several variables that could have a potential modification effect are routinely collected in these studies, such as socioeconomic status or age. The role of environmental exposures through drinking water can play an important role and contribute to cancer disparities. We encourage a systematic use of subgroup analysis to understand which populations or territories are more vulnerable to the health impacts of DBPs.