长江三角洲近岸水域表层沉积物重金属分布特征及其影响因子

采用ICP-MS测定了不同季节长江三角洲沉积物中重金属(Ni,Cu,Cr,Zn,Cd和Pb)含量并探讨了其影响因子。结果表明:(1)长江三角洲沉积物中Pb和Zn占重金属总量比例最高,Hg和Cd占重金属总量比例较小;沉积物重金属含量均以秋季和冬季最高,夏季次之,春季最低。(2)长江三角洲沉积物中Cr,Cu和Ni元素均以残渣态为主,Zn和Cd主要以弱酸提取态为主,Pb较均匀地分布于不同形态中。(3)长江三角洲沉积物中pH值和电导率基本表现为春季夏季秋季冬季,其中秋季和冬季pH值差异不显著(p0.05),二者显著低于春季和夏季(p0.05);沉积物中全碳、全氮、全磷和全钾含量均以秋季和冬季最高,夏季次之,春季最低,其中不同季节全氮和全钾含量差异均显著(p0.05)。(4)Pearson相关性分析可知,长江三角洲沉积物中Cr,Pb,Cd的弱酸浸提与重金属总量之间表现出显著的正相关关系(p0.05),而6种重金属元素的可还原态与重金属残渣态之间没有显著的相关性(p0.05);Cr,Cu,Pb的弱酸浸提与可还原态没有显著的相关性(p0.05),Ni,Zn和Cd的弱酸浸提与可还原态具有显著的相关性(p0.05)。(5)长江三角洲沉积物中6种重金属元素的不同形态均与养分等指标存在显著的正相关性,而pH值和电导率与不同形态重金属呈负相关,全碳含量是控制长江三角洲沉积物重金属元素分布的主要因素。

Distribution and Influencing Factors of Heavy Metals in Bottom Sediment of Yangtze River Delta Region During Seasons

A survey on the distribution and influencing factors of heavy metals (Ni,Cu,Cr,Zn,Cd and Pb) in bottom sediment of Yangtze River Delta region during seasons between 2014 and 2015 was carried out by using ICP-MS.The results indicated that:(1) the contents of Pb and Zn had the highest percentage of total amount of heavy metals and Hg,Cd had the lowest percentages of total amount of heavy metals,and all the heavy metal contents showed were higher in winter and autumn than those in summer and spring;(2) the contents of Cu,Cr and Ni existed in the form of acid soluble state with organic combination,Zn and Cd in water soluble form,Pb evenly distributed in five kinds of forms,and Pb had a good stability,low biological availability;(3) the values of pH and conductivity were lower in winter and autumn than those in summer and spring with significant difference in each season (p＜0.05),and the contents of nutrients were higher in winter and autumn than those in summer and spring,and the contents of the total nitrogen and total potassium had a significant difference in each season (p＜0.05);(4) the acid soluble state of Cr,Pb and Cd had a significant positive correlation with total heavy metals (p＜0.05),but the reduction state had no significant correlation with residual state (p＜0.05);(5) according to Pearson correlation analysis,pH value and conductivity were significantly negatively correlated with heavy metals (p＜ 0.05);nutrients were significantly positively correlated with heavy metals (p＜0.05),therefore,the total carbon was the important factor influencing heavy metals.