七星河湿地水环境重金属污染特征与风险评价

为识别农业区湿地水环境中重金属的污染水平、空间分布特征和风险传递效应，采集了三江平原七星河湿地水体、沉积物和鱼类样品，并测定了Cu、Cr、Cd、Zn和Ni 5种重金属的含量。结果表明:水体和沉积物中重金属的平均含量由高到低依次为Zn （28.0） > Cr （4.5） > Cu （3.2） > Ni （2.6） > Cd （0.1）（水体，μg/L）和Zn （139.4） > Cr （81.9） > Ni （45.7） > Cu （24.4） > Cd （0.2）（沉积物，mg/kg）。水体中所有重金属含量均优于GB 3838—2002《地表水环境质量标准》Ⅰ类标准，而所有采样点沉积物中的Zn和Cd均超过黑龙江省土壤背景值（Zn:70.7 mg/kg；Cd:0.086 mg/kg）。除葛氏鲈塘鳢（Perccottus glenii）未检出Ni外，东北湖鱥（Phoxinus percnurus）和北方花鳅（Cobitis granoei）中5种重金属均有检出，且北方花鳅对Zn的富集已达到"中等富集"水平，鱼类样品中其他重金属均处于"低富集"状态。以水生生物允许限值和沉积物质量指南作为参考限值的单因子风险指数（CF）的计算结果表明，水体和沉积物中的Cr对水生生物构成了"高风险"，且Cr对综合风险指数（PLI）的贡献最高。鱼类样品中5种重金属的目标危害系数（THQ）和综合危害指数（HI）均<1（Cr对HI的贡献率超过70%），表明长期食用七星河湿地野生鱼类不会引起非致癌风险，但食用野生鱼类暴露Cd的癌症风险指数（CR）超过10-5，存在引发癌症风险的可能。

POLLUTION CHARACTERISTIC AND RISK ASSESSMENT OF HEAVY METALS IN AQUATIC ENVIRONMENT OF QIXING RIVER WETLAND

The pollution levels, spatial distribution, and human health risks of heavy metals in aquatic environment of a typical wetland in Sanjiang Plain were investigated and evaluated. The concentrations of Cu, Cr, Cd, Zn, and Ni were detected in multi-media (water, sediment, and wild fish species) collected from Qixing River wetland. The results showed that the average concentration of heavy metals were in the sequence of Zn (28.0) > Cr (4.5) > Cu (3.2) > Ni (2.6) > Cd (0.1) in water (μg/L), and Zn (139.4) > Cr (81.9) > Ni (45.7) > Cu (24.4) > Cd (0.2) in sediments (mg/kg). All concentrations of heavy metals measured in the water samples were lower than China’s National Standard of Surface Water Quality I, while the concentrations of Zn and Cd in sediments were elevated and compared to the soil environmental background value of Heilongjiang. Except for the concentration of Ni in Perccottus glenii samples were below the detection limit, all the heavy metals were detected in the wild fish species. And moderate accumulation of Zn was found in Cobitis granoe, while the four other heavy metals in wild fish species were in low accumulation status. The single risk factor (CF), taking the Aquatic Life Water Permissible Limits and Sediments Quality Guideline as the reference value, indicated a high risk threat to the aquatic organisms as affected by Cr alone, and Cr contributed most to the comprehensive risk index (PLI). The target hazard quotients (THQ) and hazard indexes (HI) of these five heavy metals were bellow 1, indicating that there was no non-carcinogenic risk via consumption of wild fish; while the carcinogenic risk metrics (CR) of Cd exceeded the cancer risk threshold (10-5), indicative in elevation of cancer incidence in local consumers.