【作者】 李鸣；

【导师】 刘琪璟；

【作者基本信息】 南昌大学 ， 环境工程， 2010， 博士

【摘要】 鄱阳湖位于江西省北部,是我国最大的淡水湖泊,也是重要的保护湿地和候鸟栖息地。近年来,随着经济社会的快速发展,鄱阳湖受重金属污染的范围和程度均有所增加。2009年底,“鄱阳湖生态经济区规划”上升为国家战略,鄱阳湖生态经济区的建设将进一步加快,环鄱阳湖城市群及相关产业将蓬勃兴起,如光电产业、新能源产业、生物制药产业、铜冶炼及精深加工产业、优质钢材深加工产业、炼油及化工产业、航空产业、汽车及零部件产业等,这给鄱阳湖“永保一湖清水”,减少或者控制鄱阳湖受重金属污染的程度和范围,带来新的重要挑战。因此,对鄱阳湖受重金属污染程度进行更多的了解,研究其重金属污染特征、影响因素以及在一定环境目标下对重金属的最大承受力等是非常重要的研究课题。本文采集鄱阳湖湖区及主要河流入湖口处水体、表层沉积物及柱状沉积物样品并进行分析,全面研究鄱阳湖重金属含量水平和空间分布情况,运用相关分析法、主成分分析法等对重金属来源进行深入探讨,并结合鄱阳湖水文周期,分析鄱阳湖重金属污染的季节性变化特征。分别运用健康风险评价模型、潜在生态风险指数模型对鄱阳湖水体、表层沉积物受重金属污染程度进行评价。分析鄱阳湖重金属主要输入输出途径,运用相应重金属通量估算方法对鄱阳湖重金属出入湖通量进行估算。以II类地表水标准作为环境标准目标值,对鄱阳湖水体重金属进行对比约束,运用重金属环境容量模型,对鄱阳湖重金属环境容量进行估算。本文研究的主要结论如下：鄱阳湖水体中,Fe、Mn、Zn含量较高,且Fe>Mn>Zn,Cd最低；Pb和Cu、Zn及Cr具有相同的污染来源——大气沉降；Cu与Mn有很好的相关性,说明Cu污染来源包括自然因素；Zn和Fe,Cd与Pb、Cu及Zn可能存在拮抗作用。主成份分析表明,第一、第二和第三等前三个主成份的累积贡献率约为78.853%,大体上能够反映鄱阳湖水体中重金属污染物的基本来源情况：在第一主成份上,研究区域内重金属元素Pb、Cu、Fe、Mn表现出较高的正载荷,说明第一主成份代表所研究的各类污染来源的影响是最主要的。鄱阳湖表层沉积物中,总平均值Fe>Mn>Zn>Cu>>Pb>Cr>Cd,较上世纪末期有不同程度的改变。除Fe、Mn外,大多数重金属具有相同的人为同源性——工业废水、生活污水和大气沉降；Fe和Mn两种元素主要来源于岩石圈矿物的溶解释放,具有一定的同源性；主成份分析表明,前两个主成份的累积贡献率约为70%,大体上能够反映鄱阳湖表层沉积物中重金属污染物的基本来源情况：在第一主成份上,研究区域的重金属元素Zn、Cr、Cu、Pb、Cd表现出较高的正载荷,说明第一主成份主要代表人为污染源输入的影响；Pb在第二主成份上呈现较高正载荷,主要表征了沉积物受大气飘尘沉降的影响;Fe、Mn在第三主成份上的载荷较高,主要表征了沉积物受径流携带土壤及岩石自然风化和侵蚀的影响。鄱阳湖柱状沉积物中,湖口湖域和都昌湖域柱状沉积物重金属元素平均含量大小依次是：Fe>Mn>Zn>Cu>Pb>Cr>Cd,与表层沉积物相同。以湖口湖域柱状沉积物为例,各重金属元素含量变化规律不明显,垂直分布图均呈不规则锯齿状,多数元素含量有上升趋势。各研究元素峰值出现深度不同,Fe含量在最浅层有峰值,Cr与Cu峰值出现在-2cm,可知近年Fe、Cr、Cu污染严重；Zn、Mn、Cd和Pb峰值出现于-20cm；Zn、Mn、Cr、Cd和Pb含量在表层至-32cm间呈现锯齿多峰状,说明该时间段,其空间内主要污染物呈现多元化,异质性较大；Cu与Fe在-6cm至-18cm之间,含量较为稳定,垂直分布图中间段呈现较为平坦的部分,说明该时间段内Cu与Fe沉积量稳定,接受外源污染输入较少。相关分析和主成份分析表明,柱状沉积物中重金属主要来源于流域矿业开采、冶炼过程以及化工产业的废水排放、自然风化、侵蚀和大气沉降。鄱阳湖水体中,各种重金属含量具有较明显的季节性变化特征。在丰水期,Zn、Pb、Cu的含量出现最高值,Cd的含量在平水期1出现最高值；健康风险评价结果表明,各种重金属的健康风险值水平为：Cd>>Zn>Cu>Pb,Cd的健康风险值高出Zn、Cu、Pb的健康风险值2-4个数量级；各时期健康风险值水平为平水期1>枯水期>平水期2>丰水期。鄱阳湖重金属具有低害性特征,其水体的健康风险值水平低于国家辐射防护委员会(ICRP)推荐的最大可接受风险值水平(5.00×10-5a-1)。对鄱阳湖底泥进行生态风险评估时发现,其底泥重金属生态风险程度较低。鄱阳湖重金属污染特征受自然因素及人为因素的共同作用。自然因素中,全球气候条件变化下鄱阳湖地区气温升高,水体中悬浮物对重金属吸附量增加；雨水对尾矿中重金属的淋溶作用加剧,使尾矿、矿渣中重金属加快进入水体；强降雨作用增加了鄱阳湖地区大气重金属湿沉降、加剧了城市非点源污染及矿区重金属对水体污染；鄱阳湖湖区较强的风浪作用通过对表层沉积物的扰动促进了其中重金属释放。人为因素中,水利工程人为改变着重金属污染物在鄱阳湖区的生物地球化学行为；矿业开采属于鄱阳湖重金属的一大来源,降雨的淋溶也加剧了尾矿、矿渣中的重金属进入水体；湖区采砂通过对底泥的搅动导致重金属由底泥进入水体；船只的活动与运作加剧了重金属污染；人为调控一方面降低了鄱阳湖区域居民饮用水的健康风险,另一方面,导致重金属污染治理、控制的相对滞后,可能将给后期的防控工作增加困难。Pb、Cu、Zn、Cd等4种主要重金属出入湖通量中,溶解态、悬浮态Zn、Cu、Pb、Cd的入湖总通量均依次降低。在组成上,溶解态重金属通量普遍低于悬浮态,表明重金属在赣江、抚河、信江、饶河、修水等5河水体中的主要存在形式为悬浮态。受河流上游影响,5河重金属入湖通量相差甚大,4种重金属的入湖总通量是：赣江>饶河>信江>修水>抚河；具体分析5大河流4种重金属元素的入湖通量如下：对于Pb,赣江>信江>修水>饶河>抚河,对于Cu,赣江>信江>饶河>修水>抚河,对于Zn,赣江>饶河>信江>修水>抚河,对于Cd,赣江>信江>饶河>修水>抚河；在4种主要重金属Pb、Cu、Zn、Cd的入湖总通量中,以陆源中的5河入湖通量为主,其大小顺序为：Zn>Cu>Pb>Cd；全年出湖通量Pb、Cu、Zn、Cd等4种重金属均为悬浮态平均值>溶解态平均值,出湖重金属存在形态仍然以悬浮态为主,全年悬浮态、溶解态Pb、Cu、Zn、Cd出湖总通量均为Zn>Cu>Pb>Cd,总出湖通量为Zn>Cu>Pb>Cd。以II类地表水标准为水环境标准目标值,估算结果表明,鄱阳湖重金属Pb、Cu、Zn、Cd年均水环境容量分别为：0.63 t/a、66.86 t/a、66.59 t/a、0.33t/a；鄱阳湖重金属水环境容量的季节性差异与规律性比较明显,丰水期重金属水环境容量最高,其次为平水期,枯水期的重金属水环境容量最低；全年重金属水环境容量变化趋势为先升后降的“单峰型”。更多还原

【Abstract】 Located in northern Jiangxi Province, Poyang Lake is the largest freshwater lake in China as well as one of the important international wetlands of protection. In recent years, with the development of economic society, the pollution of heavy metals in Poyang Lake has increased both in scope and extent. Moreover, associated industries are springing up in urban agglomeration around Poyang Lake, such as photoelectric industry, new energy industry, biological industry, copper smelting and intensive processing industry, the high quality steel products processing industry, petroleum refining and chemical industry, aviation industry, automobile and automobile parts industry, etc. New crucial challenges come when we try to control the level of contamination with heavy metals. Therefore, it is an urgent subject to study the characteristics, impact factors and the maximum capacity in certain environment objective of heavy metals pollution in Poyang Lake.Based on analyzing the water of lake region and main river estuaries as well as the sample of surface sediment and columnar sediment, the content level and space distribution of heavy metals are studied comprehensively. The method of correlation analysis and principle component analysis is applied to further discuss the source of heavy metals. Analysis of the seasonal characteristics of heavy metals in Poyang Lake was combined with hydrology cycle. And health risk assessment model and the potential of the ecological risk index model are applied to evaluate the heavy metal pollution of water and surface sediments, respectively. The main input and output channels of heavy metal within Poyang Lake are analyzed and the corresponding flux calculation method is used to estimate the flux. Take Class II surface water as environmental standard target, the environmental carrying capacity of Poyang Lake is estimated. The main conclusions have been summarized as follows:In the water of Poyang Lake, the content of Fe, Mn, Zn is relatively higher which varied in descending order, while the content of Cu is minimum; Pb, Cu, Zn and Cr have the same pollution source---atmospheric sedimentation; According to the correlation between Cu and Mn, the natural factor is one of the sources of Cu pollution; Besides, Zn and Fe, Cd and Pb, Cu and Zn maybe antagonistic. Principal component analysis shows that, the cumulative contribution rate of the first three principal components is about 78.853%, which could largely reflect the basic source of heavy metals pollution in Poyang Lake Basin:based on the first principal component, Pb, Cu, Fe, Mn show higher positive-load, indicating that the first principal component represents the effect of various pollution sources.In the surface sediment of Poyang Lake, the total average value of seven heavy metals which is Fe>Mn>Zn>Cu>>Pb>Cr>Cd have different degree of changes compare with the situation at the end of the last century. Most heavy metals have the same human homology---industrial waste water, sanitary wastewater and atmospheric sedimentation, except for Fe and Mn which mainly come from the release of dissolved lithospheric mineral. According to the result of principal component analysis, the cumulative contribution rate of the first two principal components---about 70%, could largely reflect the changes of the basic source of pollution:Zn, Cr, Cu, Pb, Cd in the area showed higher positive-load in the first principal component, indicating that the first principal component mainly represents the effect of pollution by human beings; And Pb, in the second principal component, shows a higher positive-load which represents the influence of atmosphere sedimentation; Fe and Mn, with higher load in the third principal component, represent the effect of runoff, rock weathering and natural erosion.In the columnar sediment of Poyang Lake, the average content of heavy metal varies in descending order of Fe, Mn, Zn, Cu, Pb, Cr, Cd as well as in the lake of Du Chang. Take Hukou as an example, the content of heavy metal elements change irregularly with the irregular jagged vertical distribution, but most elements are in an upward trend. The elementary peak appears in different depth, Cr and Cu appeare in-2cm which shows that pollution is serious; Zn, Mn, Cd and Pb appeared in-20cm while Fe appeare in the most shallow layer. Zn, Mn, Cr, Cd and Pb from surface to-32cm are multi-peak sawtooth-shaped, indicating that this period of time within the space, the major pollutants is diversified and has large heterogeneity; While Cu and Fe appeared between-6cm and-18cm which have a relatively stable content, stating that the deposition of Cu and Fe are stable and accept little pollution outside. According to correlation analysis and principal component analysis, heavy metals in columnar sediment mainly come from mining, smelting, discharge of sewage from chemical industries, natural weathering and erosion, atmospheric sedimentation.Heavy metals obviously have seasonal characteristics in Poyang Lake. In the wet period, the concentration of Zn, Pb and Cu is the highest. The maximum value of Cd appears in the normal river flow period. According to the result of health risk assessment, the health risk level is Cd>>zn>Cu>Pb and the health risk of Cd is 2-4 orders of magnitude higher than Zn, Cu and Pb; The heavy risk level in the period ranks as:the normal river flow periodl>dry season>the normal river flow period2>wet period. Heavy metals in Poyang Lake are low harm. Its level of health risk is lower than the maximum acceptable level of risk--- (5.00×10-5a-1) which is recommended by ICRP. After the ecological risk of sediment in Poyang Lake was evaluated, the results show that ecological risk of heavy metal in sediment is also relatively low.The characteristics of heavy metal pollution are the result of natural and man-made factors. As far as natural factor, the water temperature tended to raise, in addition, the adsorption of heavy metal for suspended matter tends to increase in the condition of global climate change. Meanwhile, the eluviation of rain on heavy metal in the tailings will also increase; The effect of intensive rainfall not only increase atmospheric heavy metal wet deposition in Poyang Lake region but as well aggravate urban non-point source pollution and heavy metal pollution in mining area; Strong wind wave action also promote the release of heavy metal in surface sediment through disturbing. As far as man-made factors, the water conservancy project is artificially changing the biogeochemical behavior of heavy metal pollution in Poyang Lake, mining could be a mainly source of heavy metal, the effect of eluviation also make heavy metal from tailings into water. Sand excavation caused the pollution by agitating the sediment. The pollution is exacerbated for the activities and operation of vessels. On the one hand, artificial adjustment reduces the health risks of drinking water, on the other hand, it causes the relatively backward of administrating and controlling, which might make more difficulties in later work.According to the flux of heavy metal, the total inflow flux of Zn, Cu, Pb,Cd is decreasing in order, in general, the flux of suspended heavy metal is lower than the dissolved. Affected by the upper reaches of the river, the flux of heavy metals’ inflow among five rivers is dramatically different, the flux of four heavy metals is Ganjiang>Rao River>Xinjiang River>Xiushui>Fu River; The flux of certain kind of heavy metal in five rivers have been analyzed concretely. For the flux of Pb: Ganjiang>Xinjiang>Xiushui>Rao River>Fu River, for Cu and Cd: Ganjiang>Xinjiang>Rao River>Xiushui>Fu River, for Zn:Ganjiang>Rao River>Xinjiang>Xiushui>Fu River; The total flux value varies in the descending order of Zn, Cu, Pb, Cd, which mainly come from fiver rivers. As far as the outflow flux around the year, heavy metals mainly exist in suspended form and the total flux of four heavy metals is Zn>Cu>Pb>Cd.Take ClassⅡsurface water as environmental standard target, based on the result of estimation, the environmental capacity of Pb, Cu, Zn, Cd in Poyang Lake are 0.63t/a、66.86t/a、66.59t/a、0.33t/a, respectively. With obvious seasonal differences, the environmental carrying capacity is wet period>flow period>dry season. The environmental carrying capacity increases first and decreases afterwards around the year which shows a single peak pattern.更多还原