School of Environmental Science and Engineering, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, China.
School of Agriculture and Biology, Shanghai Jiao Tong University, No. 800, Dongchuan Road, Shanghai, 200240, China.
Chemosphere. 2021 Jul;274:129958. doi: 10.1016/j.chemosphere.2021.129958. Epub 2021 Feb 12.
Wind-driven waves and currents in shallow lakes frequently trigger the resuspension of sediments in the photic layer, which is characterized with a high pH and high dissolved organic carbon (DOC) concentration. The mechanism of phosphorus-inactivating agents (PIAs) immobilizing phosphorus under the coupled influence of pH and DOC is not clarified, and the applicability of PIAs in eutrophic shallow lakes is thus still doubtful. We found that, under the coupled influence of pH and DOC, the uptake of phosphate by LMZ was affected mainly by pH at low DOC concentrations and by DOC at high DOC concentrations. A high pH (9.3) and high DOC concentration (24.7 mg/L) greatly increased the release of phosphorus from sediment to water. However, the addition of LMZ substantially reduced the P concentrations in water, mainly via capture of dissolved inorganic phosphorus. The results of the reversibility of the adsorption of phosphates and DOC showed that phosphate had much higher affinity than DOC towards LMZ. The phosphate once adsorbed on LMZ was resistant to release when exposed to conditions of either a high pH (9.5), high DOC concentration (250 mg/L) or both; i.e., only <5% of the adsorbed phosphate is releasable. Therefore, we proposed that, to avoid the coupled influence of pH and DOC in the photic layer of eutrophic shallow lakes, LMZ could be applied in multiple low doses in the season when the growth of algae is minimal (a low pH and low DOC concentration).
风浪和浅湖中的水流经常引发光层中沉积物的再悬浮，其特征是 pH 值高和溶解有机碳 (DOC) 浓度高。在 pH 和 DOC 的耦合影响下，磷固定剂 (PIA) 固定磷的机制尚不清楚，因此 PIA 在富营养化浅水湖泊中的适用性仍然存在疑问。我们发现，在 pH 和 DOC 的耦合影响下，LMZ 对磷酸盐的吸收主要受低 DOC 浓度下 pH 的影响，受高 DOC 浓度下 DOC 的影响。高 pH（9.3）和高 DOC 浓度（24.7 mg/L）大大增加了磷从沉积物向水中的释放。然而，LMZ 的添加大大降低了水中的 P 浓度，主要是通过捕获溶解无机磷。磷酸盐和 DOC 吸附的可逆性结果表明，磷酸盐对 LMZ 的亲和力远高于 DOC。一旦磷酸盐被 LMZ 吸附，在高 pH（9.5）、高 DOC 浓度（250 mg/L）或两者的条件下，其释放受到抑制；即，只有 <5%的吸附磷酸盐是可释放的。因此，我们提出为了避免富营养化浅水湖泊光层中 pH 和 DOC 的耦合影响，可以在藻类生长最小的季节（低 pH 和低 DOC 浓度）以低剂量多次施用 LMZ。
