We studied the formation of four nitrogenous DBPs（N-DBPs） classes（haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines）, as well as trihalomethanes and total organic halogen（TOX）, after chlori...We studied the formation of four nitrogenous DBPs（N-DBPs） classes（haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines）, as well as trihalomethanes and total organic halogen（TOX）, after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.展开更多
The reclamation and disinfection of waters impacted by human activities（e.g., wastewater effluent discharges） are of growing interest for various applications but has been associated with the formation of toxic nitr...The reclamation and disinfection of waters impacted by human activities（e.g., wastewater effluent discharges） are of growing interest for various applications but has been associated with the formation of toxic nitrogenous disinfection byproducts（N-DBPs）. Monochloramine used as an alternative disinfectant to chlorine can be an additional source of nitrogen in the formation of N-DBPs. Individual toxicity assays have been performed on many DBPs, but few studies have been conducted with complex mixtures such as wastewater effluents. In this work, we compared the cytotoxicity and genotoxicity of wastewater effluent organic matter（Ef OM） before and after chloramination. The toxicity of chloraminated Ef OM was significantly higher than the toxicity of raw Ef OM, and the more hydrophobic fraction（HPO）isolated on XAD-8 resin was more toxic than the fraction isolated on XAD-4 resin.More DBPs were also isolated on the XAD-8 resin. N-DBPs（i.e., haloacetonitriles or haloacetamides） were responsible for the majority of the cytotoxicity estimated from DBP concentrations measured in the XAD-8 and XAD-4 fractions（99.4% and 78.5%, respectively）.Measured DBPs accounted for minor proportions of total brominated and chlorinated products, which means that many unknown halogenated compounds were formed and can be responsible for a significant part of the toxicity. Other non-halogenated byproducts（e.g.,nitrosamines） may contribute to the toxicity of chloraminated effluents as well.展开更多
A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewaterimpacted source waters had lower tri...A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewaterimpacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs(HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs(haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate(a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies(primarily for iodinated THMs), but seldom in full-scale studies(where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI;however, ~50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.展开更多
Dibromoacetonitrile(DBAN) is a disinfection byproduct(DBP) and linked with cancer in rodents, but the mechanism of its carcinogenicity has not been fully elucidated. We recently reported that DBAN induced inhibition o...Dibromoacetonitrile(DBAN) is a disinfection byproduct(DBP) and linked with cancer in rodents, but the mechanism of its carcinogenicity has not been fully elucidated. We recently reported that DBAN induced inhibition of nucleotide excision repair(NER). In this study, we investigated if glutathione(GSH) is involved in the DBAN-induced inhibition of NER. Human keratinocytes Ha Ca T were pretreated with L-buthionine-(S,R)-sulfoximine(BSO) to deplete intracellular GSH. BSO treatment markedly potentiated the DBAN-induced NER inhibition as well as intracellular oxidation. The recruitment of NER proteins(transcription factor IIH, and xeroderma pigmentosum complementation group G) to DNA damage sites was inhibited by DBAN, which was further exacerbated by BSO treatment. Our results suggest that intracellular GSH protects cells from DBAN-induced genotoxicity including inhibition of DNA damage repair.展开更多
基金Funding from the Australian Research Council (LP100100548)Water Corporation of Western Australia+1 种基金Curtin UniversityWater Research Australia
文摘We studied the formation of four nitrogenous DBPs（N-DBPs） classes（haloacetonitriles,halonitromethanes, haloacetamides, and N-nitrosamines）, as well as trihalomethanes and total organic halogen（TOX）, after chlorination or chloramination of source waters. We also evaluated the relative and additive toxicity of N-DBPs and water treatment options for minimisation of N-DBPs. The formation of halonitromethanes, haloacetamides, and N-nitrosamines was higher after chloramination and positively correlated with dissolved organic nitrogen or total nitrogen. N-DBPs were major contributors to the toxicity of both chlorinated and chloraminated waters. The strong correlation between bromide concentration and the overall calculated DBP additive toxicity for both chlorinated and chloraminated source waters demonstrated that formation of brominated haloacetonitriles was the main contributor to toxicity. Ozone–biological activated carbon treatment was not effective in removing N-DBP precursors. The occurrence and formation of N-DBPs should be investigated on a case-by-case basis, especially where advanced water treatment processes are being considered to minimise their formation in drinking waters, and where chloramination is used for final disinfection.
基金supported by the King Abdullah University of Science and Technology (KAUST) Office of Competitive Research Funds, entitled "Nitrogenous Disinfection By-Products in Reclaimed Wastewater Effluents: Chemistry, Toxicity and Control Strategies"
文摘The reclamation and disinfection of waters impacted by human activities（e.g., wastewater effluent discharges） are of growing interest for various applications but has been associated with the formation of toxic nitrogenous disinfection byproducts（N-DBPs）. Monochloramine used as an alternative disinfectant to chlorine can be an additional source of nitrogen in the formation of N-DBPs. Individual toxicity assays have been performed on many DBPs, but few studies have been conducted with complex mixtures such as wastewater effluents. In this work, we compared the cytotoxicity and genotoxicity of wastewater effluent organic matter（Ef OM） before and after chloramination. The toxicity of chloraminated Ef OM was significantly higher than the toxicity of raw Ef OM, and the more hydrophobic fraction（HPO）isolated on XAD-8 resin was more toxic than the fraction isolated on XAD-4 resin.More DBPs were also isolated on the XAD-8 resin. N-DBPs（i.e., haloacetonitriles or haloacetamides） were responsible for the majority of the cytotoxicity estimated from DBP concentrations measured in the XAD-8 and XAD-4 fractions（99.4% and 78.5%, respectively）.Measured DBPs accounted for minor proportions of total brominated and chlorinated products, which means that many unknown halogenated compounds were formed and can be responsible for a significant part of the toxicity. Other non-halogenated byproducts（e.g.,nitrosamines） may contribute to the toxicity of chloraminated effluents as well.
基金funding from the National Science Foundation (CBET 1705206 and 1706862)。
文摘A survey was conducted at eight U.S. drinking water plants, that spanned a wide range of water qualities and treatment/disinfection practices. Plants that treated heavily-wastewaterimpacted source waters had lower trihalomethane to dihaloacetonitrile ratios due to the presence of more organic nitrogen and HAN precursors. As the bromide to total organic carbon ratio increased, there was more bromine incorporation into DBPs. This has been shown in other studies for THMs and selected emerging DBPs(HANs), whereas this study examined bromine incorporation for a wider group of emerging DBPs(haloacetaldehydes, halonitromethanes). Moreover, bromine incorporation into the emerging DBPs was, in general, similar to that of the THMs. Epidemiology studies that show an association between adverse health effects and brominated THMs may be due to the formation of brominated emerging DBPs of heath concern. Plants with higher free chlorine contact times before ammonia addition to form chloramines had less iodinated DBP formation in chloraminated distribution systems, where there was more oxidation of the iodide to iodate(a sink for the iodide) by the chlorine. This has been shown in many bench-scale studies(primarily for iodinated THMs), but seldom in full-scale studies(where this study also showed the impact on total organic iodine. Collectively, the THMs, haloacetic acids, and emerging DBPs accounted for a significant portion of the TOCl, TOBr, and TOI;however, ~50% of the TOCl and TOBr is still unknown. The correlation of the sum of detected DBPs with the TOCl and TOBr suggests that they can be used as reliable surrogates.
基金supported by the Kurita Water and Environment Foundation (No. 18E030)JSPS KAKENHI Grant Number 19K15793。
文摘Dibromoacetonitrile(DBAN) is a disinfection byproduct(DBP) and linked with cancer in rodents, but the mechanism of its carcinogenicity has not been fully elucidated. We recently reported that DBAN induced inhibition of nucleotide excision repair(NER). In this study, we investigated if glutathione(GSH) is involved in the DBAN-induced inhibition of NER. Human keratinocytes Ha Ca T were pretreated with L-buthionine-(S,R)-sulfoximine(BSO) to deplete intracellular GSH. BSO treatment markedly potentiated the DBAN-induced NER inhibition as well as intracellular oxidation. The recruitment of NER proteins(transcription factor IIH, and xeroderma pigmentosum complementation group G) to DNA damage sites was inhibited by DBAN, which was further exacerbated by BSO treatment. Our results suggest that intracellular GSH protects cells from DBAN-induced genotoxicity including inhibition of DNA damage repair.
