DH-Ⅰ型SMFC传感器产电信号对连续多次镉污染的响应研究

本研究考察了一种自主研发的新型沉积物微生物燃料电池传感器(命名为DH-I型SMFC传感器)产电信号对连续多次Cd~(2+)污染事件的响应特征.采用淹水土壤模拟湿地环境,将该传感器的阳极(不锈钢管)插入淹水土壤中,阴极(铂网)位于上覆水下方.分别向每个传感器阴极上方的上覆水中加入50 mL Cd~(2+)浓度为25、50、100、200 mg·L~(-1)的CdCl_2溶液,对照加入50 mL去离子水.每天早晚各加入一次Cd~(2+)污染,连续加入27 d,即每个传感器各加入53次相同浓度的CdCl_2溶液.结果表明,每次加入Cd~(2+)污染后,电压均迅速上升,在30 s内达到峰值后逐渐回落到稳定状态;并且电压增量(峰值电压与基线电压的差值)随着加入的Cd~(2+)浓度增加而升高;而相同Cd~(2+)浓度53次加入引起的电压增量具有较好的一致性.土壤产电细菌的代表类群地杆菌科(Geobacteraceae)和梭菌属(Clostridium)16S rRNA基因丰度均未随着Cd~(2+)浓度的增加而降低.针对土壤中不同形态Cd~(2+)浓度的检测结果表明,0～3 cm的表层土壤吸附了大量Cd~(2+),使得土壤中的产电细菌免受Cd~(2+)的抑制,从而该传感器产电信号能够在湿地环境中,原位在线监测多次Cd~(2+)污染.

The response of electrical signals generated by DH-I type sediment microbial fuel cell based sensors to multipal cadmium pollution

A novel sediment microbial fuel cell (SMFC) based sensor (DH-I type SMFC sensor) was developed to study the response of electrical signals to repeated Cd²⁺ pollution. Soil was flooded with water to simulate wetland. The anode (stainless steel tube) of the sensors were inserted into the flooded soil, and the cathode (platinum mesh) was located beneath the overlying water. In five sensors, 50 ml CdCl₂ solution with 25, 50, 100 and 200 mg·L^-1 Cd²⁺, and deionized water as control were added to the overlying water. For each sensor, CdCl₂ solution was supplemented for twice a day in consecutive 27 days, with a total of 53 times. The results show that the voltage increased rapidly with each addition of Cd²⁺ and reached a peak within 30 s, then gradually decreased to a stable state. With the increase of Cd²⁺ concentration, the voltage increments (the difference between peak voltage and baseline voltage) increased. The voltage increments were similar among every CdCl₂ addition. The 16S rRNA gene abundance of Geobacteraceae and Clostridium, which were the representative of exoelectrogenic bacteria, did not decrease with the increase of Cd²⁺ concentration. The results of different forms of Cd²⁺ in soil show that a large amount of Cd²⁺ was adsorbed in the surface soil (0~3 cm), which protected the exoelectrogenic bacteria in soil from being inhibited by Cd²⁺. We suggest that the electrical signals of sensors could be used in situ and on line monitoring the events of heavy metal pollution in wetlands.