Vione Davide, Saglia Federica, Pelazza Carola
Department of Chemistry, University of Torino, Via Pietro Giuria 5, 10125 Torino, Italy.
Molecules. 2023 Oct 13;28(20):7072. doi: 10.3390/molecules28207072.
In temperate environments, climate change could affect water pH by inducing enhanced dissolution of CaSO followed by biological sulphate reduction, with the potential to basify water due to H consumption. At the same time, increased atmospheric CO could enhance weathering of carbonate rocks (e.g., dolomite) and increase the total concentration of dissolved carbonate species. Both processes enhance phototransformation by the carbonate radical (CO), as shown for the non-steroidal anti-inflammatory drug paracetamol, provided that the dissolved organic carbon of water does not undergo important fluctuations. Climate change could also affect hydrology, and prolonged drought periods might considerably decrease flow rates in rivers. This is a substantial problem because wastewater pollutants become less diluted and, as a result, can exert more harmful effects due to increased concentrations. At the same time, in low-flow conditions, water is also shallower and its flow velocity is decreased. Photochemical reactions become faster because shallow water is efficiently illuminated by sunlight, and they also have more time to occur because water takes longer to cover the same river stretch. As a result, photodegradation of contaminants is enhanced, which offsets lower dilution but only at a sufficient distance from the wastewater outlet; this is because photoreactions need time (which translates into space for a flowing river) to attenuate pollution.
在温带环境中，气候变化可能会通过促使硫酸钙的溶解增强，随后进行生物硫酸盐还原，从而影响水体pH值，由于消耗了氢离子，存在使水体碱化的可能性。与此同时，大气中二氧化碳含量的增加可能会增强碳酸盐岩（如白云石）的风化作用，并增加溶解的碳酸盐类物质的总浓度。这两个过程都会增强碳酸根自由基（CO）引发的光转化作用，如非甾体抗炎药对乙酰氨基酚的情况所示，前提是水体中的溶解有机碳不会发生显著波动。气候变化还可能影响水文情况，长期干旱期可能会大幅降低河流流速。这是一个严重的问题，因为废水污染物的稀释程度降低，结果是由于浓度增加而可能产生更有害的影响。同时，在低流量条件下，河水也更浅，流速降低。光化学反应会加快，因为浅水能被阳光有效照射，而且由于水流过相同河段所需时间变长，光化学反应也有更多时间发生。结果是污染物的光降解作用增强，这抵消了稀释程度降低的影响，但前提是距离废水排放口有足够的距离；这是因为光反应需要时间（对于流动的河流而言这转化为空间）来减轻污染。
