Center for Water Environment Studies, Ibaraki University, Itako, Ibaraki, Japan.
Sci Total Environ. 2010 Mar 15;408(8):1932-42. doi: 10.1016/j.scitotenv.2010.01.016. Epub 2010 Feb 11.
Soil cores and rainwater were sampled under canopies of Cryptomeria japonica in four montane areas along an atmospheric depositional gradient in Kanto, Japan. Soil cores (30cm in depth) were divided into 2-cm or 4-cm segments for analysis. Vertical distributions of elemental enrichment ratios in soils were calculated as follows: (X/Al)(i)/(X/Al)(BG) (where the numerator and denominator are concentration ratios of element-X and Al in the i- and bottom segments of soil cores, respectively). The upper 14-cm soil layer showed higher levels of Cu, Zn, As, Sb, and Pb than the lower (14-30cm) soil layer. In the four areas, the average enrichment ratios in the upper 6-cm soil layer were as follows: Pb (4.93)>or=Sb (4.06)>or=As (3.04)>Zn (1.71)>or=Cu (1.56). Exogenous elements (kg/ha) accumulated in the upper 14-cm soil layer were as follows: Zn (26.0)>Pb (12.4)>Cu (4.48)>or=As (3.43)>or=Sb (0.49). These rank orders were consistent with those of elements in anthropogenic aerosols and polluted (roadside) air, respectively, indicating that air pollutants probably caused enrichment of these elements in the soil surface layer. Approximately half of the total concentrations of As, Sb, and Pb in the upper 14-cm soil layer were derived from exogenous (anthropogenic) sources. Sb showed the highest enrichment factor in anthropogenic aerosols, and shows similar deposition behavior to NO(3)(-), which is a typical acidic air pollutant. There was a strong correlation between Sb and NO(3)(-) concentrations in rainfall (e.g., in the throughfall under C. japonica: [NO(3)(-)]=21.1 [dissolved Sb], r=0.938, p<0.0001, n=182). Using this correlation, total (cumulative) inputs of NO(3)(-) were estimated from the accumulated amounts of exogenous Sb in soils, i.e., 16.7t/ha at Mt. Kinsyo (most polluted), 8.6t/ha at Mt. Tsukuba (moderately polluted), and 5.8t/ha at the Taga mountain system (least polluted). There are no visible ecological effects of these accumulated elements in the Kanto region at present. However, the concentrations of some elements are within a harmful range, according to the Ecological Soil Screening Levels determined by the U.S. Environmental Protection Agency.
在日本关东地区，沿大气沉降梯度的四个山区，在柳杉树冠下采集了土壤芯和雨水样本。土壤芯（深度 30cm）分为 2cm 或 4cm 段进行分析。土壤中元素富集比的垂直分布计算如下：（X/Al）（i）/（X/Al）（BG）（其中分子和分母分别是芯土壤 i 段和底部段中元素-X 和 Al 的浓度比）。上层 14cm 土壤层的 Cu、Zn、As、Sb 和 Pb 含量高于下层（14-30cm）土壤层。在四个地区，上层 6cm 土壤层的平均富集比如下：Pb（4.93）≥Sb（4.06）≥As（3.04）≥Zn（1.71）≥Cu（1.56）。上层 14cm 土壤层中积累的外源元素（kg/ha）如下：Zn（26.0）>Pb（12.4）>Cu（4.48）≥As（3.43）≥Sb（0.49）。这些排序与人为气溶胶和污染（路边）空气中元素的排序一致，表明空气污染物可能导致土壤表层元素的富集。上层 14cm 土壤层中约一半的 As、Sb 和 Pb 总浓度来自外源（人为）来源。Sb 在人为气溶胶中具有最高的富集因子，并且表现出与 NO3-相似的沉积行为，NO3-是一种典型的酸性空气污染物。降雨中 Sb 与 NO3-浓度之间存在很强的相关性（例如，在柳杉的穿透雨中：[NO3-]=21.1[溶解 Sb]，r=0.938，p<0.0001，n=182）。利用这种相关性，从土壤中外源 Sb 的积累量估算了总（累积）NO3-的输入量，即在污染最严重的金山（Mt. Kinsyo）为 16.7t/ha，在筑波山（Mt. Tsukuba）为 8.6t/ha，在 Tagayama 系统（least polluted）为 5.8t/ha。目前，在关东地区，这些积累元素没有明显的生态影响。然而，根据美国环境保护署确定的生态土壤筛选水平，一些元素的浓度处于有害范围之内。
