摘要:
为研究汉江上游水体沉积物污染状况及其来源,以汉江上游水体17个样点沉积物为对象,测定了沉积物中有机氯化合物(α-666;β-666;γ-666;δ-666;4,4’-DDE;4,4’-DDD;2,4’-DDT;4,4’-DDT)和重金属元素(V、Cr、Mn、Co、Ni、Cu、Zn、As、Cd、Pb)的含量,采用地累积指数法和潜在生态风险指数评价了重金属污染状况,并结合冗余分析和多元统计分析探讨沉积物理化性质与重金属的关系以及重金属的来源。结果表明,所有样点沉积物中有机氯化合物的含量水平均较低,未对生态环境产生影响,但仍需注意预防此类污染;所有样点重金属除Cd为偏强度污染程度外,其余元素均显示为无污染—轻度污染程度。潜在生态风险分析显示,重金属元素总体处于极重潜在风险,对环境造成污染的样点中贡献最大的是Cd,是研究区域环境生态风险的主要影响因子;冗余分析表明该研究区域沉积物的理化性质和重金属含量没有显著性关系;多元统计分析表明,Cd、Pb可能与农业生产资料(化肥、农药等)的施用和工业“三废”的排放有关,属于人为源; V、Cr、Mn、Co、Ni、Cu、Zn、As的含量主要与岩石的自然风化有关,部分样点与工业废水和农业活动有关,污染源主要是自然源。综合研究表明,由Cd污染为主的汉江上游沉积物重金属潜在生态危害应引起重视。
Abstract:
To ascertain the pollution characteristics and source of sediments in the upper reaches of the Hanjiang River, this study collected sediment samples at 17 sampling sites in the study area. Based on these samples, this study determined the concentrations of organochlorine compounds (α-666;β-666;γ-666;δ-666;4,4'-DDE;4,4'-DDD;2,4'-DDT; and 4,4'-DDT) and heavy metals (V, Cr, Mn, Co, Ni, Cu, Zn, As, Cd, and Pb) in the sediments. Then, it assessed the heavy metal pollution using the geoaccumulation and potential ecological risk indices. Furthermore, through redundancy analysis and multivariate statistical analysis, this study explored the sources of heavy metals and the relationships between the physicochemical properties of the sediments and heavy metals concentrations. The results indicate that: (1) The organochlorine compounds in the sediments at all sampling sites show low concentrations, without affecting the ecological environment. However, attention should be paid to the pollution caused by organochlorine compounds; (2) All the heavy metals from the sampling sites show non-pollution or mild pollution, except for Cd, which caused slightly strong pollution; (3) As revealed by the analysis of potential ecological risks, heavy metals generally show extremely high potential risks. Cd, which causes the most serious environmental pollution at the sampling sites, serves as the main factor influencing the environmental and ecological risks in the study area; (4) The redundancy analysis shows that there is no significant relationship between the physicochemical properties of sediments and the concentrations of heavy metals in the study area; (5) As revealed by the multivariate statistical analysis, Cd and Pb may be related to the application of agricultural materials (e.g., chemical fertilizers and pesticides) and the discharge of waste gas, wastewater, and industrial residue, indicating anthropogenic sources; the concentrations of V, Cr, Mn, Co, Ni, Cu, Zn, and As are related to the natural weathering of rocks mainly and to industrial wastewater and agricultural activities partially, indicating dominant natural sources. The comprehensive study shows that the potential ecological hazards caused by heavy metals (dominated by Cd) in the sediments should be treated seriously.
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