重点区域建设用地污染地块特征分析

以我国工业发展的重点区域京津冀、长三角和珠三角为研究对象,基于2018~2021年纳入《建设用地土壤污染风险管控和修复名录》的共496个污染地块,对其区域分布、土壤和地下水超标污染物特征、污染的行业相关性、场地地质条件等数据进行相关数据统计分析。结果表明:京津冀污染地块主要分布于京津和冀南,长三角污染地块数量最大且分布广,珠三角污染地块则密布于珠江口。整体上土壤污染以重金属-有机复合污染为主(48.43%),地下水则是有机污染占比(42.49%)最大。化学原料及化学品制造业和金属冶炼及延压加工业污染地块风险负荷指数大于0.25,为较高风险;塑料和橡胶制品业、机械制造、金属制品业、电器机械及器材制造业和皮革、皮毛制造业污染地块为中风险,其余行业污染地块为低风险。场地土壤和地下水污染分布与历史行业类型息息相关,如土壤中化学原料及化学品制造业超标污染物种类最复杂,卤代烃(占比12%)和苯系物(占比10.4%)相比其余行业占比更重,地下水中各行业重金属污染和常规指标如氨氮需要关注。土层深度上各类典型污染物最大超标普遍分布在0~5m,整体上重金属最大污染超标深度大于有机污染最大超标深度;土壤性质方面超标污染则更集中于黏性土等低渗透性土层。

Characterization of contaminated construction sites in key regions

In this paper, three key regions of industrial development in China were investigated(i.e., Beijing-Tianjin-Hebei, Yangtze River Delta and Pearl River Delta regions), based on the 496contaminated sites included in the List of Soil Contamination Risk Control and Remediation of Construction Sites from 2018 to 2021. Statistical analysis was conducted on the regional distribution, soil-groundwater excess contamination characteristics, industry contamination correlation and geological conditions of the sites. The results showed that: The contaminated sites of Beijing-Tianjin-Hebei region were mainly located in Beijing-Tianjin and southern Hebei Province. The number of contaminated sites of Yangtze River Delta is the largest and the sites were widely distributed. The contaminated sites of Pearl River Delta is densely located in the Pearl River Estuary. Generally,soil contamination was dominated by the combined contamination of organic pollutants and heavy metals(48.43%), while groundwater was dominated by organic contamination(42.49%). High risk industries were chemical raw material and chemical manufacturing, metal smelting and rolling processing industry, with the risk load index greater than 0.25. The industry types of medium risk contaminated sites were plastics and rubber products industry, machinery manufacturing, metal products industry, electrical machinery and equipment manufacturing, and leather and fur manufacturing industry. The rest industry types of contaminated sites are low risk. The characteristics of the site soil-groundwater contamination were closely related to the historical industries. For example, the chemical raw materials and chemicals manufacturing industry, having the most diverse contaminations with halogenated hydrocarbons (12% of the total) and benzene (10.4% of the total), accounted for a heavier proportion than the rest of the industries. At the same time, heavy metal contamination in groundwater was serious in all industries, and conventional indicators such as ammonia nitrogen should also be noted. The maximum soil depth of exceedance for all types of typical contaminants was generally 0~5m at soil depth. The maximum soil depth of exceedance for heavy metals was greater than organic contamination. In terms of soil properties, the excess contamination was concentrated in low permeability layers such as clayey soils.