高风险四环素抗性基因在人工湿地中分布和去除的季节变化

畜禽养殖废水是抗生素抗性基因(ARGs)的重要贮存库,环境风险不容忽视。本研究考察了夏、冬两季养猪废水中高环境风险四环素抗性基因(TRGs)在水平潜流人工湿地中的分布和去除情况,通过外源添加四环素(TC)和铜离子(Cu²⁺)探究了养猪废水中抗生素与重金属单一和复合污染对湿地出水中TRGs丰度的影响。结果表明: 养猪废水中3种高环境风险TRGs(tetM、tetO、tetW)均有检出,人工湿地可有效消减废水中的TRGs,夏、冬两季时出水中TRGs的绝对丰度较进水分别降低1.1～2.4和1.7～2.9个数量级。TRGs在湿地土壤中的丰度呈现出水端低于进水端、植物非根际低于根际、冬季低于夏季的特征。与对照相比,养猪废水中TC、Cu²⁺单一和复合污染在夏、冬两季均会导致湿地出水中TRGs相对丰度的增加。人工湿地作为一种生态处理工艺可用于控制畜禽养殖废水中的ARGs向环境中扩散。

Seasonal variation of distribution and removal of high-risk tetracycline resistance genes in constructed wetland.

Livestock wastewater is an important reservoir of antibiotic resistance genes (ARGs), with high environmental risks. We investigated the seasonal variations of distribution and removal of swine wastewater originated high-risk tetracycline resistance genes (TRGs) in horizontal subsurface flow constructed wetlands. The effects of exogenous addition of tetracycline (TC) and copper ion (Cu²⁺) on the abundance of TRGs in effluent with single and combined pollution of antibiotic and heavy metal were studied. The results showed that all the three high-risk TRGs (tetM, tetO and tetW) were detected in swine wastewater. Wetlands could effectively reduce the ARGs, with the absolute abundance of TRGs in effluent being decreased by 1.1-2.4 and 1.7-2.9 orders of magnitude in summer and winter compared with the influent, respectively. The abundance of TRGs in wetland soils showed the characte-ristics that the outflow side was lower than the inflow side, the non-rhizosphere area was lower than the rhizosphere area, and lower in winter than in summer. In summer and winter, single and combined pollution of TC and Cu²⁺ in swine wastewater would increase the abundance of TRGs in effluent compared with that in the control. The constructed wetland is suitable for controlling the environmental diffusion of ARGs in livestock wastewater.