RESUMEN

Climate change affects the concentration and characteristics of dissolved organic matter (DOM) in surface water. The changes in composition of DOM have many implications to drinking water quality, especially in the case of formation of disinfection by-products (DBPs). The aim of this study was to investigate the formation of nitrogenous DBPs (N-DBPs) during chlorination and chloramination, caused by the alternation of surface water's DOM driven by climate change. For this reason, two different cases were examined: (a) rise of algal organic matter (AOM) due to water blooming and (b) water enrichment by humic substances. The target compounds were haloacetonitriles (HANs), haloacetamides (HAcAms), and halonitromethane (TCNM). The results showed that Anabaena appears to be a major precursor for HAcAms and TCNM, while humic acids are precursors for HANs. The results of the mixtures presented the same pattern. During the water blooming case, HAcAms and TCNM formation are in favor, while during water enrichment by humic substances case, HANs is the N-DBP group with higher formation yield. Cloraminated samples presented higher values of cytotoxicity and genotoxicity compared to the chlorinated.

RESUMEN

Climate change causes heavy rainfall incidents and sea level rise, which have serious impact on the availability and quality of water resources. These extreme phenomena lead to the rise of external and internal precursors in water reservoirs, and consequently affect the formation of disinfection by-products (DBPs). The aim of this study was to investigate the formation of nitrogenous_DBPs (N-DBPs) under extreme conditions caused by climate change. For this reason, two scenarios were adapted: a) sea level rise leading to increase of water salinity and b) heavy rainfall incidents leading to flooding events. The target-compounds were haloacetonitriles (HANs), haloacetamides (HAcAms) and halonitromethane (TCNM). Chlorination and chloramination were employed as disinfection processes under different doses (5 and 10 mg/L) and contact times (24 and 72 h). The results showed enhancement on the formation of N-DBPs and changes in their profile. Sea level rise scenario led to elevated concentrations of brominated species (maximum concentration of dibromoacetonitrile 23 µg/L and maximum concentration of bromoacetamide 57 µg/L), while flooding events scenario led to extended formation of chloroacetamide and bromochloroacetonitrile up to 58 µg/L and 40 µg/L, respectively. At the same time, changes in cytotoxicity and genotoxicity of the samples were observed.

RESUMEN

Understanding the processes that underlay an ecological disaster represents a major scientific challenge. Here, we investigated phytoplankton and zooplankton community changes before and during a fauna mass kill in a European protected wetland. Evidence on gradual development and collapse of harmful phytoplankton blooms, allowed us to delineate the biotic and abiotic interactions that led to this ecological disaster. Before the mass fauna kill, mixed blooms of known harmful cyanobacteria and the killer alga Prymnesium parvum altered biomass flow and minimized zooplankton resource use efficiency. These blooms collapsed under high nutrient concentrations and inhibitory ammonia levels, with low phytoplankton biomass leading to a dramatic drop in photosynthetic oxygenation and a shift to a heterotrophic ecosystem phase. Along with the phytoplankton collapse, extremely high numbers of red planktonic crustaceans-Daphnia magna, visible through satellite images, indicated low oxygen conditions as well as a decrease or absence of fish predation pressure. Our findings provide clear evidence that the mass episode of fish and birds kill resulted through severe changes in phytoplankton and zooplankton dynamics, and the alternation on key abiotic conditions. Our study highlights that plankton-related ecosystem functions mirror the accumulated heavy anthropogenic impacts on freshwaters and could reflect a failure in conservation and restoration measures.

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RESUMEN

This study investigated the occurrence of disinfection by-products (DBPs) (trihalomethanes (THMs), haloacetic acids (HAAs), halonitriles (HANs), halonitromethane (TCNM) and haloketones (HKs)) in different type of swimming pools in the area of Thessaloniki, northern Greece by employing the EPA methods 551.1 and 552.3. Moreover, general water quality parameters (pH, residual chlorine, dissolved organic carbon, UV254 absorption, total nitrogen, alkalinity and conductivity) were also measured. The concentrations of DBPs showed great variability among swimming pools as well as within the same pool between sampling campaigns. HAAs exhibited the highest concentrations followed by THMs, HANs, TCNM and HKs. Exposure doses for four age groups (3-<6 y, 6-<11 y, 11-<16 y and adults) were calculated. Route-specific exposures varied among DBPs groups. Inhalation was the dominant exposure route to THMs and TCNM (up to 92-95%). Ingestion and dermal absorption were the main exposure routes to HAAs (40-82% and 18-59%, respectively), depending on the age of swimmers. HANs contributed up to 75% to the calculated cytotoxicity of pool water. Hazard indices for different exposure routes were <1, suggesting non-carcinogenic risk. Inhalation posed the higher carcinogenic risk for THMs, whereas risk via oral and dermal routes was low. Ingestion and dermal contact posed the higher risk for HAAs. Risk management strategies that minimise DBPs exposure without compromising disinfection efficiency in swimming pools are necessary.

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