盲数优化地积累模型评价长江中下游湖泊沉积物重金属污染

盲数优化地积累模型是基于最大隶属度原则和隶属度加权相结合的一种不确定性评价方法。鉴于污染评价系统多种不确定信息共存的特点,将盲数优化地积累模型应用于长江中下游不同类型湖泊沉积物中重金属污染程度评价中。根据计算出的可能值区间及可信度看空间分布的均匀性,以及评价等级的可信度水平,辨识污染程度和等级,减小局部污染对区域整体污染程度的影响。结果表明:象湖、鄱阳湖、洞庭湖3个湖泊表层沉积物中的重金属的空间分布都不均匀,象湖表层沉积物中重金属的污染情况为:PbCuZn,其中Pb为中度污染,Cu为轻度污染,Zn为清洁;鄱阳湖沉积物中重金属污染评价结果为Cu﹥Pb﹥Zn,其中Cu为中度污染,Pb为偏中度污染,Zn为偏重污染;洞庭湖沉积物中重金属污染评价结果为Cu≈Pb≈Zn,且均为轻度污染。盲数优化地积累模型方法可行,与定性评价结果基本一致,但在对污染等级判定上更真实可靠。弥补了传统确定性方法的不足,更真实、更客观地表征了评价区域沉积物重金属的富集污染程度。

EVALUATION OF HEAVY METAL POLLUTION IN THE SEDIMENTS OF THE LAKES FROM THE MIDDLE AND LOWER REACHES OF YANGTZE RIVER BY OPTIMIZING GEO-ACCUMULATION MODEL BASED ON BLIND NUMBER THEORY

Currently, there are many methods for evaluating heavy metal pollution, and most of these methods are based on deterministic approaches rather than uncertainty evaluation methods. Recently, the Blind Number Theory is attracting more and more international attention for the evaluation of heavy metal pollution. This theory is based on an uncertainty point of view. Optimizing geo-accumulation model based on the Blind Number Theory is an uncertainty evaluation method, and it combines the principle of maximum degree of membership and the weighting degree of membership. Application of the Blind Number Theory in the area of pollution evaluation was different from the traditional deterministic pollution assessment method. The Blind Number Theory is suitable for the coexistence and uncertainty complex systems, especially suitable for evaluation of heavy metal contamination. Considering that the pollution assessment system involves many uncertain characteristics of information, the blind number optimization geo-accumulation model was applied to evaluate the heavy metal pollution of the sediments in the different types of lakes from the middle and lower reaches of Yangtze River based on the Blind Number Theory. Three typical heavy metals including Copper (Cu), lead (Pb) and zinc (Zn) were selected as the main indicators for heavy metals contamination evaluation. According to the equality of the spatial distribution from the computed possible value and reliability as well as the rating reliability level, the pollution degree and level were identified, and the influence of the local pollution on overall regional pollution was reduced. The results showed that the spatial distributions of heavy metals from the surface sediments of Xianghu Lake, Poyang Lake, Dongting Lake were not uniform. The heavy metal pollution of the surface sediments from Xiang Lake showed a trend of Pb > Cu > Zn. Pb was a moderate pollution, and Cu was slightly polluted, but Zn was clean. The heavy metal pollution in the sediments of Poyang Lake showed a trend of Cu > Pb > Zn. Cu was a moderate pollution, Pb was a partially moderate pollution, and Zn was a partially heavy pollution. The heavy metal pollution from the sediments of Dongting Lake was Cu ≈ Pb ≈ Zn, at a level of slight pollution. The blind number optimization geo-accumulation model was a feasible method, which was basically the same as the qualitative evaluation results, but more reliable to the determination of the pollution level. Moreover, the optimizing geo-accumulation model based on the Blind Number Theory could make the deficiencies of the traditional deterministic method and it could demonstrate the heavy metal accumulation pollution degree of the sediments in the evaluated regions more authentically and objectively. This method could provide new ideas for the methods of heavy metal pollution evaluation, and it can also provide a more reliable basis for environmental management and decision-making.