哈尔滨松江湿地重金属空间分布及潜在生态风险评价

为了解哈尔滨松江湿地沉积物中重金属的污染程度，对其表层沉积物中8种重金属元素（Hg、Cd、As、Cu、Pb、Cr、Ni、Zn）的含量及其空间分布进行研究，并采用地累积指数法和潜在生态风险评价法对表层沉积物重金属污染程度进行评价.结果表明:①松江湿地沉积物中w（Cd）、w（Hg）和w（Pb）的平均值均高于松嫩平原土壤环境背景值，表明Cd、Hg、Pb这3种重金属元素存在富集.②相关分析显示，沉积物中w（TOC）、w（TN）均与各重金属含量之间存在相关性，而pH与各重金属含量无相关性.主成分分析显示，8种重金属可被辨识为2个主成分，即Cr、Ni、Cu、Zn和Pb为人为复合源因子，As、Cd和Hg为农业源因子.空间分析显示，松江湿地沉积物中Ni、Cu、Zn和Cr主要分布在阿什河口和白鱼泡湿地，As、Cd和Hg主要分布在金河湾、阿什河口和白鱼泡湿地，Pb主要分布在阿什河口湿地.③地积累指数（I_geo）评价表明，在所有采样点中Cd和Hg分别处于轻度和偏中度污染水平，其他元素均处于无污染水平.④潜在生态风险指数分析结果表明，松江湿地重金属的潜在生态风险主要是由Cd和Hg引起，二者贡献率分别为33.4%和57.6%；整个研究区综合潜在生态风险指数（RI）介于135.28~733.27之间，平均值为234.47，属于中度污染.8个采样区的生态风险指数依次为阿什河口>金河湾>白鱼泡>太平庄滩>松江>呼兰河口>滨江>太阳岛，其中，阿什河口湿地达到了较高污染，其他采样区均为中度污染.研究显示，松江湿地表层沉积物中重金属存在生态风险，其中以阿什河口湿地风险为最高. 

Distribution and Potential Ecological Risk Assessment of Heavy Metals in the Sediment of the Songjiang Wetland in Harbin City

This article explores heavy metal pollutants in the Songjiang Wetland in Harbin City. The contents and spatial distribution of eight heavy metals (Hg, Cd, As, Cu, Pb, Cr, Ni and Zn) in the sediment collected from the Songjiang Wetland were determined. The integrated pollution index and geoaccumulation index were used to estimate the degree of heavy metal contamination in the surface sediments. The results indicate that:(1)w(Cd), w(Hg) and w(Pb) were higher than that in the Songnen Plain, suggesting these heavy metals were enriched in Songjiang Wetland area. (2) The correlation analysis show that the content of heavy metals had significant correlation with w(TOC) and w(TN), but there was no correlation with pH. PCA shows that two principal components were identified from the eight heavy metals. Cd, Cr, Zn and Pb were mainly influenced by anthropogenic activities, and Cu and Ni were controlled by agricultural sources. Spatial analysis showed that Ni, Cu, Zn and Cr in the sediments of the Songjiang Wetland were mainly distributed in the Arshen Estuary and Whitefish Bubble, and As, Cd and Hg were mainly distributed in the Golden Bay, Arshen Estuary and Whitefish Bubble. Pb was mainly distributed in the Arshen Estuary. (3) The geoaccumulation index assessment suggested that the order of the pollution degree values of the eight heavy metals in the surface sediments of the Songjiang Wetland was Hg > Cd > As > Pb > Cu > Cr > Ni > Zn. In all samples, Cd and Hg belonged to a low and partial moderate pollution statue, while As, Pb, Cu, Cr, Ni and Zn belonged to a no pollution statue for the majority of samples. (4) The potential ecological risk index assessment suggested that the potential ecological risk of heavy metals was primarily caused by Cd and Hg in the Songjiang Wetland, which were 33.4% and 57.6%, respectively. The integrated pollution index assessment indicated that the average potential ecological risk index (RI) of the Songjiang Wetland was 234.47 (ranged from 135.28 to 733.27), which is considered to be moderate pollution. The ecological risk index of the eight sampling areas, in order, was the Arshen Estuary > Golden Bay > Whitefish Bubble > Taipingzhuang > Beach > Songjiang > Hulan River > Binjiang > Sun Island. The Arshen Estuary Wetland had the highest pollution, and the other areas were only moderately polluted. The results suggest there are potential ecological risks in the Songjiang Wetland due to heavy metal pollution and the biggest risks are at the Arshen Estuary Wetland.