摘要
长江沿江全流域的重金属元素镉异常带引发了人们对沿长江流域城市的镉及其他重金属元素的环境地球化学特征及生态效应的关注。本文以长江流域具有重要的经济发展战略意义的武汉为研究区,对长江武汉段沿岸的冲积土壤中主要重金属元素镉、铜、铅、镍、铬的含量和以BCR法分步提取的弱酸提取态、可还原态、可氧化态和残渣态等4种形态的分量进行了较系统的分析,同时,配套分析了蔬菜样品中的重金属元素镉、铜、铅、镍、铬的含量,以便了解重金属元素的环境地球化学特征。结果显示,长江武汉段沿岸的冲积土壤中,重金属镉含量超标;铅、铜、镍元素含量接近国家土壤环境质量标准二级指标,基本上对植物和环境不造成危害和污染,满足一般农田、蔬菜地、茶园、果园、牧场等土壤环境标准;铬元素含量较低,接近其背景值。长江武汉段沿岸的冲积土壤中重金属元素的含量和活动性强的弱酸提取态分量随着采样点位置距离武汉钢铁厂越近而增大,显示重金属污染的部分原因可能是工业生产造成的。重金属元素在表层土壤中存在积累效应,表现为表层土壤中重金属元素含量高于对应深层的含量。重金属元素的形态分布特征与各自的地球化学性质有关,活动性强的弱酸提取态镉和铅分量高,具有潜在的环境危害。这些土壤中种植的蔬菜中,重金属元素镉含量普遍明显超标,部分蔬菜中铅元素含量超标,铜、镍、铬元素含量正常。
More and more attention has been given on the environmental geochemical characteristics and ecological effect of heavy metals, especially, after Cd anomalies along the whole Yangtze River basin had been indicated in many researches in recent years. Therefore, Wuhan city, a city with important significance of development strategy, was selected as the study area. The environment geochemistry of heavy metals in the alluvial soils of Yangtze River （Wuhan segment） was studied in this paper. The concentrations of heavy metals in alluvial soil of Yangtze River and corresponding vegetable samples collected from Wuhan city were determined by AAS after microwave digested. Four fractions of soil heavy metals, weak acid soluble fraction, reducible fraction, oxidizable fraction and residual fraction, were extracted in the alluvial soils by BCR （European Community Bureau of Reference） sequential extraction procedure. It is showed that the soil was contaminated by Cadmium （Cd） with Cd contents significantly higher than the allowable value. Lead （Pb）, copper （Cu） and nickel （Ni） contents in soil samples were close to the allowable values, did not cause harm and pollution on plants and environment, and met the national soil environmental standards for general farmland, vegetables, tea plantations, orchards and pasture. Chromium（Cr） concentrations in soil samples were close to its background values. The heavy metals pollution is probably caused partly by the production of Wuhan Steel and Iron Company as the closer the sampling sites are to it the higher of heavy metal contents were. The concentrations of heavy metals in topsoil are greater than that in deeper soils. High concentrations of weak acid extraction of heavy metals, with strong activities, are potentially harmful to environment. It is also showed that Cd and Pb contents in vegetables are greater than the allowable values. However, concentrations of Cu, Ni and Cr are acceptable.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2016年第8期1955-1964,共10页
Acta Geologica Sinica
基金
国家自然科学基金项目(41171237)
中央级公益性科研院所基本科研业务费专项项目(AS2013J11)
国土资源大调查项目(1212011220598)项目资助的成果
关键词
冲积土壤
重金属
分步提取形态分析
环境地球化学
长江
alluvial soils
heavy metals
sequential extraction procedure
environment geochemistry
Yangtze River
