Quantitative Assessment of Variability and Uncertainty of Hazardous Trace Element (Cd, Cr, and Pb) Contents in Chinese Coals by Using Bootstrap Simulation
Quantitative Assessment of Variability and Uncertainty of Hazardous Trace Element (Cd, Cr, and Pb) Contents in Chinese Coals by Using Bootstrap Simulation
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DOI：
10.3155/1047-3289.61.7.755
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发表时间：
2011-07
影响因子：
2.7
通讯作者：
H. Tian;K. Cheng;Yan Wang;Dan Zhao;F. Chai;Z. Xue;J. Hao
中科院分区：
文献类型：
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作者：
H. Tian;K. Cheng;Yan Wang;Dan Zhao;F. Chai;Z. Xue;J. Hao
摘要 有害微量元素（HTE）含量不确定性的定量测量是更好地评估煤炭地球化学和矿物学特征及其环境影响的基础。本文采用自举模拟方法，展示了一种定量程序来表征中国 27 个不同省份和矿区煤炭中 HTE（Cd、Cr 和 Pb）含量的变异性和不确定性。中国煤炭中镉、铬和铅含量的原始数据样本是根据已发表文献报道的结果进行汇编和总结的。计算统计中不确定性的抽样分布，例如平均值、中位数和置信区间。全国平均镉含量约为 0.61 微克/克，铬含量为 30.37 微克/克，铅含量为 23.04 微克/克。全国HTE含量自举样本的不确定度范围基本对称，算术平均值的95%置信区间范围较小，Cd的相对不确定度为-16.39%至+21.31%，Cr的相对不确定度为-10.11%至+11.72%，Pb的相对不确定度为-8.55%至+8.64%。这表明，我国煤炭中HTEs的算术平均含量南方省份高于北方省份，且因产煤盆地不同而存在明显差异。 HTE含量较高的省区为四川、重庆、云南、湖北、广西等。含量较低的省份位于中国西北部，包括新疆、青海、甘肃、内蒙古；这主要归因于煤炭的含水量中等、灰分低、硫含量低。宁夏Cd、广东Cr、陕西Pb等HTE含量较高的几个省份可能与原始数据样本的代表性有关。影响 HTE 对环境和公共健康的负面影响日益受到全世界的关注。含量测定过程中的错误可能会导致HTE排放清单出现较大偏差。决策者有必要了解煤炭和排放清单中 HTE 含量的优势和局限性，以便做出对不确定性具有鲁棒性的空气质量管理决策。本研究提供了中国煤炭中HTE含量的定量评估方法，为评估煤炭的地球化学和矿物学特征及其潜在环境影响提供了基础，并有助于制定煤炭中HTE的概率排放清单。然而，仍然需要更多的研究。
ABSTRACT The quantitative measurements of uncertainties regarding the contents of hazardous trace elements (HTEs) serve as a basis for better assessment of the geochemistry and mineralogical characteristics of coals and their environmental impacts. In this paper, by using bootstrap simulation methodology, a quantitative procedure was demonstrated to characterize the variability and uncertainty of HTE (Cd, Cr, and Pb) contents in Chinese coals, which were specified by 27 different provinces and mining areas. Original data samples for Cd, Cr, and Pb contents in Chinese coals were compiled and summarized from the results reported in published literature. Sampling distributions for uncertainties in statistics such as the mean, median, and confidence interval were calculated. The national average contents were estimated at approximately 0.61 μg/g for Cd, 30.37 μg/g for Cr, and 23.04 μg/g for Pb. The ranges of uncertainties for bootstrap samples of national HTE contents were nearly symmetrical, and the ranges of the 95% confidence interval for the arithmetic mean were relatively small, with relative uncertainties of −16.39% to +21.31% for Cd, −10.11% to +11.72% for Cr, and −8.55% to +8.64% for Pb. This shows that the arithmetic mean contents of HTEs in Chinese coals are higher in southern provinces than those in northern provinces, obviously differing because of different coal basins. The high values of HTE contents occur in provinces such as Sichuan, Chongqing, Yunnan, Hubei, and Guangxi. Provinces with low contents are located in northwestern China and include Xinjiang, Qinghai, Gansu, and Inner Mongolia; this can be mainly attributed to the medium moisture content, low ash, and low sulfur content in coals. Several provinces with high HTE contents such as Ningxia for Cd, Guangdong for Cr, and Shaanxi for Pb may be associated with the representativeness of the original data samples. IMPLICATIONS The negative effects of HTEs on the environment and public health have received increasing concern throughout the world. Errors during content determination may lead to large bias of the HTE emission inventories. It is necessary for decision-makers to be aware of the strengths and limitations of HTE contents in coals and emission inventories so that decisions regarding air quality management can be made that are robust to uncertainty. This study provides a quantitative assessment methodology for HTE contents in Chinese coals that will serve as a basis for assessing the geochemistry and mineralogical characteristics of coals and their potential environmental impacts and be helpful in developing probabilistic emission inventories of HTEs from coal. However, more research is still needed.