土壤产电信号与线性扫描伏安法联用模拟监测湿地铜污染

本研究采用产电信号与线性扫描伏安法(LSV)联用,探索快速响应和鉴定湿地铜污染的方法。采集湖岸土壤并淹水用以模拟湿地环境,构建土壤产电体系并实时连续记录土壤产电电压。土壤产电60 h后,分别向体积为145 ml的淹水层中加入5 ml Cu~(2+)浓度为300(T1)、600(T2)、1 200(T3)、2 400 mg/L(T4)的溶液。铜加入后,T1和T2处理的电压迅速降低,T3和T4处理的电压迅速上升,之后所有电压缓慢回到加铜前的水平。加铜后2 h,在淹水土壤中设置三电极体系并采用线性扫描伏安法(LSV)对污染物进行定性检测,结果显示,LSV曲线在0.162~0.182 V范围内出现单个氧化峰,峰电流值随溶液中Cu~(2+)浓度增加而升高。为解释土壤产电信号变化特征,对加铜前后电流、阴极电势和内阻进行了检测,结果显示,加铜后T1处理电流降低,阴极电势无明显变化;T2处理电流无明显变化,阴极电势上升;而T3、T4处理电流和阴极电势都出现了明显的升高,且T4处理的内阻最低。本研究为实现土壤产电信号在监测污染方面的实际应用提供了参考。

Combining Use of Soil Generated Electrical Signals and Linear Sweep Voltammetry to Stimulate Copper Pollution Monitoring in Wetland

This study combines the use of soil generated electrical signals and linear sweep voltammetry to explore a way to quickly response and identify copper pollution in wetland. Soil was collected in a forest in Nanjing City and flooded to simulate the wetland. The systems for soil to generate electricity were constructed and soil generated voltage data were recorded in time and continuously. Sixty hours after soil started to generate electricity, a volume of 5 ml Cu²⁺ solution was added into the overlaying water above the flooded soil to stimulate an event of copper pollution in wetland. The designed Cu²⁺ concentrations of the solution were 300 (T1), 600 (T2), 1 200 (T3) and 2 400 mg/L (T4), respectively. Soil generated voltage showed response immediately after Cu²⁺ addition, including the sudden decline for T1 and T2 treatments, and quick increase for T3 and T4 treatments. Later the voltage went back to the level before Cu²⁺ addition. Two hours after Cu²⁺ addition, a three-electrode mode was set in the flooded soil followed by the LSV to identify copper pollution, and the results showed that single oxidative peak appeared within the range from 0.162 V to 0.182 V in LSV curve and the peak current increased with increasing Cu²⁺ concentration. In order to interpret the response of soil generated voltage to Cu²⁺ addition, soil generated current, cathodic potential and impedance were measured before and after copper addition. After the addition of Cu²⁺, the current of T1 treatment decreased while its cathodic potential was not dramatically changed; the current of T2 treatment did not changed while its cathodic potential increased; the current and cathodic potential increased for both T3 and T4 treatment, and the internal resistance was the lowest for T4 treatment. This study may provide a reference for using soil generated electrical signals to monitor pollution.