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铁(Fe)和锰(Mn)均为氧化还原敏感性元素,是水质评价的重要指标之一.为了解南亚热带地区供水水库夏季Fe、Mn的垂直分布特征,于2016年7月调查了粤东地区9座水库敞水区湖沼学变量和Fe、Mn浓度的垂直分布特征.在有明显温度分层的深水水库中Fe、Mn存在显著的梯度分布,表层水体中总Fe(TFe)、总Mn(TMn)以及溶解性Fe、Mn(DFe、DMn)的浓度显著(TFe,F=6.708,P=0.032;TMn,F=9.720,P=0.014;DFe,F=8.129,P=0.029;DMn,F=11.125,P=0.016)低于底层.5座深水水库底层水体中TFe、TMn平均浓度分别为0.399 mg·L~(-1)和0.422 mg·L~(-1),其中溶解态离子占70%以上,而在没有明显温度分层的浅水水库中,表层水体TFe、TMn以及DFe、DMn浓度略低于底层但无显著性差异(TFe,F=0.135,P=0.726;TMn,F=0,P=1;DFe,F=0.006,P=0.943;DMn,F=0.007,P=0.936),4座浅水水库底层水体中TFe、TMn平均浓度分别为0.110 mg·L~(-1)和0.089 mg·L~(-1),且主要以非溶解态存在.水体中TFe和DFe浓度与溶解氧(DO)浓度、p H值和深度呈显著相关关系(P<0.05),与总磷(TP)、总氮(TN)浓度没有显著相关性.水体热分层及高的水体稳定性导致DO和p H值呈现明显的梯度分布,是导致深水水库Fe、Mn在水层间形成梯度分布的关键原因.深水水库底层水体低DO浓度和酸性条件有利于沉积物中Fe、Mn的释放,是导致Fe、Mn以溶解态存在的主要原因.同时,以红壤为主的土壤类型可能是该地区水体中Fe、Mn普遍较高的重要原因.以上结果表明,南亚热带地区夏季分层稳定的深水水库底层水体普遍存在Fe、Mn较高的现象,以深层取水的供水方式易出现Fe、Mn浓度超标,湖上层取水则可避免该问题.
Both iron (Fe) and manganese (Mn) are redox-sensitive elements and are one of the important indexes for evaluating water quality.In order to understand the vertical distribution characteristics of Fe and Mn in the summer subtropical water supply reservoirs, Vertical distribution characteristics of limnology variables and concentrations of Fe and Mn in 9 open-water reservoirs in the East China.The distributions of Fe and Mn in deep-water reservoirs with obvious temperature stratification show a significant gradient distribution, total Fe (TFe), total The concentrations of Mn (TMn) and soluble Fe and Mn (DFe, DMn) were significant (TFe, F = 6.708, P = 0.032; TMn, F = 9.720, P = 0.014; DFe, F = 8.129, , F = 11.125, P = 0.016) were lower than the bottom.The average concentrations of TFe and TMn in the bottom water of the five deep water reservoirs were 0.399 mg · L -1 and 0.422 mg · L -1, respectively, of which dissolved state Ions accounted for more than 70%, while in shallow water reservoirs without obvious temperature stratification, TFe, TMn and DFe, DMn concentrations in surface waters were slightly lower than those in bottom waters (TFe, F = 0.135, P = 0.726; TMn, The average concentrations of TFe and TMn in the bottom water of four shallow water reservoirs were 0.110 mg · L ~ (-1), F = 0, P = 1, DFe, F = 0.006, P = 0.943, DMn, F = 0.007, 1) and 0.089 mg · L -1, and mainly exist in the undissolved state There was a significant correlation between DFe concentration and dissolved oxygen (DO) concentration, p H value and depth (P <0.05), and no significant correlation with total phosphorus (TP) and total nitrogen The stability of water body leads to the obvious gradient distribution of DO and p H, which is the key reason that causes the gradient distribution of Fe and Mn in the water layer of the deepwater reservoir.The low DO concentration and acidic conditions in the bottom water of the Sham Shui reservoir are favorable for Fe, The release of Mn is the main reason for the existence of Fe and Mn in dissolved state.At the same time, the type of soil dominated by red soil may be the reason for the generally high Fe and Mn in the water body of the area.The above results show that the summer subtropical zone The phenomenon of high Fe and Mn is common in the bottom water of stratified and stable deepwater reservoirs. Fe and Mn are prone to appear in the water supply ways of deep water intake, and can be avoided by taking water at the upper lake.