Turnbull Rose, Rogers Karyne, Martin Adam, Rattenbury Mark, Morgan Richard
GNS Science, Private Bag 1930, Dunedin, New Zealand.
National Isotope Centre, GNS Science, PO Box 30-312, Lower Hutt, New Zealand.
Sci Total Environ. 2019 Jul 10;673:455-469. doi: 10.1016/j.scitotenv.2019.04.063. Epub 2019 Apr 10.
We present results from the first urban chemical and isotopic soil baseline survey to be completed for a New Zealand city. The major, minor, trace and isotopic composition of soils from different depths across the city of Dunedin are shown to be spatially variable due to geogenic and anthropogenic influences. Based on Principal component analysis (PCA) for the shallow soil depth, at least 40% (PC1 and PC3) of the dataset variance is attributed to a geogenic source. Soils enriched in Al, Cr, Fe, Hf, Mo, Ni, Th, Ti, U, V and Zr (PC1) are spatially associated with mapped units of the basaltic Dunedin Volcanic Group, indicating a geogenic source. An anthropogenic influence is attributed to at least 23% (PC2 and PC5) of the dataset variance. The chemical elements As, B, Bi, Cd, Cu, P, Pb, Sb, Sn and Zn (PC2) are strongly spatially associated with soils sampled above high-density urban residential, commercial and industrial sites, and are interpreted to reflect heavy metal contamination from human activities. In conjunction with historical vehicle emissions from leaded petrol, we suggest that legacy leaded paint from residential, commercial and industrial buildings flaking into Dunedin City soils is a significant contributor to Pb in the Dunedin urban environment. Median heavy metal contents for shallow soils (0-2 cm) from a variety of land-uses throughout Dunedin City are shown to be almost an order of magnitude greater than median heavy metal concentrations in soils from regional baselines. Significantly, urban anthropogenic sources of heavy metals, and C, N and S isotopes are shown to exert a stronger influence on soil composition than rural anthropogenic sources. Results from this study provide an important case-study for urban soil contamination for a relatively young city from the Southern Hemisphere, for which there are currently few examples.
我们展示了针对新西兰一座城市完成的首次城市土壤化学和同位素基线调查的结果。由于地质和人为影响，达尼丁市不同深度土壤的主要、次要、微量元素及同位素组成呈现出空间变异性。基于浅层土壤深度的主成分分析（PCA），至少40%（PC1和PC3）的数据方差归因于地质源。富含铝、铬、铁、铪、钼、镍、钍、钛、铀、钒和锆（PC1）的土壤在空间上与玄武岩达尼丁火山群的测绘单元相关联，表明其源自地质源。至少23%（PC2和PC5）的数据方差归因于人为影响。化学元素砷、硼、铋、镉、铜、磷、铅、锑、锡和锌（PC2）在空间上与高密度城市住宅、商业和工业用地之上采集的土壤紧密相关，并被解释为反映了人类活动造成的重金属污染。结合过去含铅汽油的车辆排放情况，我们认为住宅、商业和工业建筑剥落的遗留含铅油漆进入达尼丁市土壤是该市城市环境中铅的一个重要来源。达尼丁市不同土地利用类型的浅层土壤（0 - 2厘米）中重金属含量中位数几乎比区域基线土壤中的重金属浓度中位数高一个数量级。值得注意的是，城市人为来源的重金属以及碳、氮和硫同位素对土壤组成的影响比农村人为来源更强。这项研究的结果为南半球一个相对年轻的城市的城市土壤污染提供了一个重要的案例研究，目前此类案例较少。
