在温带环境中,气候变化可能通过诱导CaSO4溶解增强,然后生物硫酸盐还原来影响水的pH值,由于H+消耗,具有碱化水的潜力。同时,大气二氧化碳的增加可能会增强碳酸盐岩的风化(例如,白云石)并增加溶解碳酸盐物种的总浓度。这两个过程都通过碳酸酯自由基(CO3·-)增强了光转化,如非甾体抗炎药扑热息痛所示,前提是水的溶解有机碳不会发生重大波动。气候变化也会影响水文,长期干旱可能会大大降低河流的流速。这是一个实质性的问题,因为废水污染物变得不那么稀释,因此,由于浓度增加,可能会产生更多的有害影响。同时,在低流量条件下,水也更浅,其流速降低。光化学反应变得更快,因为浅水被阳光有效地照亮,它们也有更多的时间发生,因为水需要更长的时间来覆盖同一条河流。因此,污染物的光降解增强,这抵消了较低的稀释,但只能在离废水出口足够远的地方;这是因为光反应需要时间(转化为流动河流的空间)来减轻污染。
In temperate environments, climate change could affect water pH by inducing enhanced dissolution of CaSO4 followed by biological sulphate reduction, with the potential to basify water due to H+ consumption. At the same time, increased atmospheric CO2 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 (CO3•-), 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.