ABSTRACT

Mercury (Hg) is a pollutant that can affect human and ecosystem health. The transport and fate of Hg in the environment are dynamic and complex, but our understanding remains unclear for Japanese forest ecosystems. Here, we report the first country-wide survey of Hg concentrations in litter and surface mineral soil layers in 42 forest stands across Japan. The median concentrations of Hg in the litter layer and 0–10 cm of mineral soils were 99 (range: 56.7–297) and 145 (range: 22.8–294) μg kg⁻¹, respectively, and tended to decrease down to 50 cm. There was a positive relationship between the Hg and total organic carbon concentrations in soil, suggesting that organic carbon strongly binds with Hg in soil. There was a significant positive correlation between the Hg and lead concentrations in the litter layer. Partial least square regression analysis indicated that the soil and litter properties as well as the atmospheric and geological Hg concentrations and some soil characteristics such as soil pH, organic matter properties and soil physical factors were effective explanatory variables of the country-wide spatial patterns of Hg concentrations in litter and mineral soil. In addition, we found the influence of atmospheric Hg is stronger in litter layer, whereas the influences of geological and soil factors are stronger in mineral soil. These results suggest that air pollution partly affects the spatial patterns of Hg concentrations in litter and soil of Japanese forests under the given geological and soil conditions at the country scale.

摘要

汞（Hg）是一种污染物，可能会影响人类和生态系统的健康。汞在环境中的迁移和命运是动态的和复杂的，但是我们对日本森林生态系统的理解仍不清楚。在这里，我们报告了全国范围内首次对全国42个林分的凋落物和表层矿物土壤层中的汞浓度进行的全国性调查。枯枝落叶层和0–10 cm矿质土壤中Hg的平均浓度为99（范围：56.7–297）和145（范围：22.8–294）μgkg ^-1，并倾向于减小到50厘米。汞与土壤中总有机碳浓度之间存在正相关关系，表明有机碳与土壤中的汞牢固结合。垃圾层中的汞和铅浓度之间存在显着的正相关。偏最小二乘回归分析表明，土壤和凋落物的特性以及大气和地质汞的浓度以及土壤的某些特性（例如pH，有机质特性和土壤物理因素）是全国范围内汞空间格局的有效解释变量。垃圾和矿物土壤中的浓度。此外，我们发现在凋落物层中，大气汞的影响更强，而在矿物土壤中，地质和土壤因素的影响更强。