ABSTRACT An experimental flooding with freshwater was used to evaluate the biogeochemical impacts of freshening in a semi-arid floodplain wetland that had undergone severe secondary salinisation (Loveday Disposal Basin, Australia). Filling the wetland with freshwater lowered electrical conductivity (EC) from ~60 to 13 dS m–1. This freshening was accompanied by substantial declines in total P (TP), filterable reactive P (FRP), dissolved organic C (DOC), total organic N (TON), dissolved organic N (DON), NH4+ and molybdenum-reactive Si (MoR Si) concentrations. Owing to the semiarid climate, the water level receded and EC increased to pre-flooding conditions within seven months. During this drying phase, some chemical species maintained lower concentrations then pre-flooding (TP and FRP), others returned to within their original range (DOC, TON, DON), and others went above their original range (NH4+ and MoR Si), the latter reflecting some bank discharge of groundwater. Unexpectedly low turbidity and P concentrations during the drying phase were promoted by the development of an extensive filamentous algal mat following flooding, which limited sediment resuspension as the water level receded. The transient response to freshening highlights that salinity is a key driver of biogeochemical cycles in semi-arid wetlands.

中文翻译：

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次生盐渍化漫滩湿地对实验清新的生物地球化学响应

摘要 用淡水进行的实验性洪水被用来评估在经历了严重次生盐渍化的半干旱泛滥平原湿地（澳大利亚洛夫迪处理盆地）中淡水的生物地球化学影响。用淡水填充湿地将电导率 (EC) 从 ~60 降低到 13 dS m-1。这种清新伴随着总磷 (TP)、可过滤活性磷 (FRP)、溶解有机碳 (DOC)、总有机氮 (TON)、溶解有机氮 (DON)、NH4+ 和钼活性硅 (MoR) 的大幅下降Si) 浓度。由于半干旱气候，水位在七个月内下降，EC 增加到洪水前的条件。在这个干燥阶段，一些化学物质的浓度低于预驱（TP 和 FRP），另一些则恢复到原来的范围内（DOC、TON、DON），而其他的则超过了它们的原始范围（NH4+ 和 MoR Si），后者反映了地下水的一些堤岸排放。洪水之后形成了广泛的丝状藻垫，这促进了干燥阶段出乎意料的低浊度和 P 浓度，这限制了随着水位下降沉积物的再悬浮。对清新的瞬态响应凸显了盐度是半干旱湿地生物地球化学循环的关键驱动因素。