Department of Geology, 0224 Old Main Bldg., Wayne State University, Detroit, MI 48202, USA.
Environ Pollut. 2013 Aug;179:1-12. doi: 10.1016/j.envpol.2013.03.053. Epub 2013 Apr 23.
A chronological sequence of urban soils 3-92 years old was studied to determine the effects of time on morphogenesis, artifact weathering, and the geochemical partitioning of Pb. Key chronofunctions determined are an increase in ˆA horizon Development Index (defined herein based on soil color) and water-soluble Pb, and a decrease in pH and C/N, with increasing soil age. Key artifact weathering reactions are: 1) portlandite in mortar altered to calcite, 2) ferrite in wrought-iron altered to ferrihydrite and goethite, and 3) carbonaceous materials altered to water-soluble organic substances. Mortar and wrought-iron were found to be Pb-bearing, but weather to produce immobilizing agents. Hence, they are both a source and a sink for Pb. The origin and mobilization of water-soluble Pb is complex and probably includes microbial extracellular polymeric substances, biodegraded soil organic matter, and solubilized organic substances derived from carbonaceous anthropogenic microparticles (soot, char and coal-related wastes).
研究了 3 至 92 年的城市土壤时间序列，以确定时间对形态发生、人为风化和 Pb 的地球化学分配的影响。确定的关键时间函数是土壤颜色定义的 A 层发育指数和水溶性 Pb 的增加，以及 pH 和 C/N 的降低，随土壤年龄的增加而增加。关键的人为风化反应是：1）砂浆中的氢氧化钙转变为方解石，2）熟铁中的铁素体转变为水铁矿和针铁矿，3）含碳物质转变为水溶性有机物质。发现砂浆和熟铁含有 Pb，但风化会产生固定剂。因此，它们既是 Pb 的来源又是 Pb 的汇。水溶性 Pb 的来源和迁移是复杂的，可能包括微生物细胞外聚合物、生物降解的土壤有机质以及源自含碳人为微粒（烟尘、炭和与煤有关的废物）的可溶解有机物质。
