某焦化场地土壤中多环芳烃分布的三维空间插值研究

为准确界定污染场地土壤中多环芳烃在3维条件下的污染分布范围和受污染土方量,选择我国某焦化污染场地苯并(a)芘分布为研究对象,对比研究Krig-3D、IDW-Shepard、IDW-(Franke/Nielson)以及Nearest Neighbor 4种3维插值方法对界定污染范围的不确定性影响。结果表明,不同3维插值模型计算结果差异较大,交叉验证结果显示Krig-3D插值模型插值精度最高,插值结果能较真实地反映场地实际污染情况。通过修复目标对比确定进一步表明,基于4种插值模型计算所得的污染土壤土方量分别为8.51×105、5.62×105、7.12×105、1.09×106m3,选择合理的插值模型将对预测污染范围的不确定性产生重要影响。研究结果对分析污染范围和修复治理过程土方量确定提供重要参考。

3D interpolation of soil PAHs distribution in a coking contaminated site of China

Contaminated sites are an environmental issue of concern all over the world, especially some large-scale industrial contaminated sites, which are key objects for environmental supervision and risk management in many countries. In recent years, following rapid economic development and adjustments of industrial structure, polluting industrial plants were commonly closed or moved out of developing cities, and the quantity and degree of contamination of the remaining industrial contaminated sites appeared to be rising. Soil contamination of industrially contaminated sites has received widespread attention in China, and not only directly affects the soil physicochemical properties and the environment, but also threatens human health in the contaminated area. Industrial contaminated sites severely restricted the availability of urban land resources for sustainable development. The regional soil environment is an important part of the whole ecological environment system; the original ecological functions and system balance of the regional soil environment was destroyed initially by the industrial contaminated sites. The contaminants in the soils threaten organisms and human health through migration and transformation. The presence of industrial contaminated sites has significant impacts on the sustainable development of the regional economy, reuse of land resources, laws and regulations, and relevant industry standards, which has attracted great attention from the relevant Chinese government departments. Environmental risk management of contaminated sites in China lack fully developed laws or management systems when compared to more developed countries, however, the theoretical basis and technology needed to perfect these is required immediately. According to the management and application requirements in China, new theory and technology research was deemed indispensable. Knowledge of the spatial distribution of available pollutants is critical for risk control, remedial strategy development and for determination of remediation boundaries and soil volumes. Pollution characteristics of contaminated sites are different from general non-point source pollution as they are influenced by human disturbance and accumulative release, forming hotspots that exist in the local region of contaminated sites. Commonly used spatial interpolation methods can provide an unbiased prediction with minimum variance for the concentration of a given pollutant, but the interpolation techniques all have a smoothing effect, which underestimates locally high values and overestimates locally low values. The uncertainty in determining contamination boundaries at contaminated sites is affected by spatial interpolation methods. In order to determine the PAHs pollutant boundary and soil volumes needing restoration, different prediction models had an influence on the uncertainty of determining the polluted boundary. Thus, a large domestic coking contaminated site was selected; four 3D interpolation models of Krig-3D, IDW-Shepard, IDW-(Franke/Nielson), and Nearest Neighbor were employed to compare their reliability and prediction uncertainty. A significant difference between model results was observed, and cross-validation testing indicated that the Krig-3D was more accurate in predicting the actual pollution situation. Referring to the remediation goal, the polluted soil volumes calculated using the four 3D interpolation models were 8.51?105, 5.62?105, 7.12?105, and 1.09?106 m3, respectively. This study, based on typical field site data, provides a great contribution to the analysis of pollution spatial distribution characteristics and determination of remediation soil volumes.