AOM Lab, School of Chemical Engineering, The University of New South Wales, Sydney, Australia.
Curtin Water Quality Research Group, School of Molecular and Life Sciences, Curtin University, Perth, Australia; ChemCentre, Perth, Australia.
Water Res. 2020 Sep 15;183:116047. doi: 10.1016/j.watres.2020.116047. Epub 2020 Jun 16.
Algal cells and algal organic matter (AOM) are a source of high dissolved organic carbon (DOC) and nitrogen (DON) concentrations. This poses a possible health risk due to their potential to form disinfection by-products (DBPs), some of which may be of health concern, after disinfection. While several studies have focussed on the formation of carbonaceous DBPs from AOM, only a few studies have focussed on the formation of nitrogen containing N-DBPs from AOM. Hence, the main aim of this study was to thoroughly investigate the N-DBP formation potential of the AOM from a species of cyanobacteria commonly found in natural waters, Microcystis aeruginosa. Three haloacetonitriles, two halonitromethanes, two haloacetamides, and eight N-nitrosamines were analysed by gas chromatography-mass spectrometry after chlorination and chloramination of the extracted AOM. To provide further insight into the influence of changing DON character on N-DBP formation potential, the AOM from three other species, Chlorella vulgaris, Dolichospermum circinale and Cylindrospermopsis raciborskii, were also tested. Dichloroacetonitrile (DCAN) was the DBP formed in the highest concentrations for both chlorination and chloramination of bulk AOM from all the species. Furthermore, during chlorination and chloramination, the high molecular weight fraction (>1 kDa) of AOM from M. aeruginosa had a greater DCAN formation potential (normalised to DOC or DON) than the AOM in the low molecular weight fraction (<1 kDa) of M. aeruginosa, regardless of growth stage. N-Nitrosamine formation from the bulk AOM of all species occurred only after chloramination. The molar concentration of N-nitrosodimethylamine (NDMA) was lower than the other N-nitrosamines detected. However, NDMA formation increased with culture age for all four species, in contrast to most other N-nitrosamines whose formation remained consistent or decreased with culture age. Overall, algal growth could result in elevated concentrations of N-DBPs due to the increasing concentrations of high molecular weight algal DON in the AOM. It is suggested that the AOM comprises precursors containing long C-chain amine (R-NH-R) or cyclic N-containing amine structures. Comparisons to previously measured N-DBP concentrations in drinking water suggest that the AOM from the algae and cyanobacteria examined in this study are not likely to be a major source of precursors for either DCAN or NDMA in real waters. However, AOM may present a major precursor source for other N-nitrosamines.
藻类细胞和藻类有机物质（AOM）是高溶解性有机碳（DOC）和氮（DON）浓度的来源。由于它们在消毒后形成消毒副产物（DBPs）的潜力，其中一些可能对健康构成威胁，因此这可能带来健康风险。尽管有几项研究集中在从 AOM 形成碳质 DBPs 上，但只有少数研究集中在从 AOM 形成含氮的 N-DBPs 上。因此，本研究的主要目的是深入研究从常见于天然水中的蓝藻物种铜绿微囊藻中提取的 AOM 的 N-DBP 形成潜力。通过气相色谱-质谱法分析了三种卤乙腈、两种卤代硝基甲烷、两种卤代乙酰胺和八种 N-亚硝胺，这些物质是在提取的 AOM 氯化和氯胺化后产生的。为了更深入地了解不断变化的 DON 特性对 N-DBP 形成潜力的影响，还测试了来自三种其他物种的 AOM，即普通小球藻、螺旋鱼腥藻和柱孢鱼腥藻。对于所有物种的 AOM 进行氯化和氯胺化时，二氯乙腈（DCAN）是形成浓度最高的 DBP。此外，在氯化和氯胺化过程中，铜绿微囊藻高分子量（>1 kDa）部分的 DCAN 形成潜力（归一化为 DOC 或 DON）高于铜绿微囊藻低分子量（<1 kDa）部分，无论生长阶段如何。所有物种的 AOM bulk 只有在氯胺化后才会形成 N-亚硝胺。二甲基亚硝胺（NDMA）的摩尔浓度低于检测到的其他 N-亚硝胺。然而，与大多数其他 N-亚硝胺随着培养年龄的增加而减少或保持不变不同，所有四种物种的 NDMA 形成都随着培养年龄的增加而增加。总的来说，由于 AOM 中高分子量藻类 DON 浓度的增加，藻类生长可能导致 N-DBP 浓度升高。研究结果表明，AOM 包含含有长 C 链胺（R-NH-R）或环状含氮胺结构的前体。与之前在饮用水中测量的 N-DBP 浓度进行比较表明，在本研究中检查的藻类和蓝藻的 AOM 不太可能成为实际水中 DCAN 或 NDMA 的主要前体来源。然而，AOM 可能是其他 N-亚硝胺的主要前体来源。
