Chen Dazhou, Liu Wenjie, Liu Xiande, Westgate John N, Wania Frank
Chinese Research Academy of Environmental Sciences, Beijing 100012, China.
Environ Sci Technol. 2008 Dec 15;42(24):9086-91. doi: 10.1021/es8018572.
In the Chinese province of Sichuan steep mountains rise from the very densely populated and intensely cultivated Chengdu basin more than 4000 elevational meters to the Tibetan Plateau. This steep physical gradient is exceptionally well suited to investigate the transport of persistent pesticides and other organic contaminants from low to high elevations. In spring and autumn 2006, 25 soil samples were taken at five elevations ranging from 2636 to 4479 m along the East-facing slope of Balang Mountain in Wolong Nature Reserve. Analysis of soil extracts was done by gas chromatography-high resolution mass spectrometry. Whereas hexachlorobenzene (HCB), hexachlorocyclohexanes (HCH), and dichlorodibenzotrichloroethane and its degradation products (DDTs) were present at levels of a few ng/g, only two light PCB congeners were detected at levels below 1 ng/g in soil. Soil concentration for all analytes increased significantly and exponentially with altitude. The rate of concentration increase, expressed quantitatively through the slope of the linear regression between the logarithm of the concentrations and altitude, increases along the sequence HCB < PCB < HCH < or = DDT. This trend is consistent with, and therefore lends additional observational support to, a mountain cold-trapping mechanism based on the temperature dependence of precipitation scavenging.
在中国四川省，从人口密集、耕种频繁的成都盆地拔地而起的陡峭山脉，海拔超过4000米直抵青藏高原。这种陡峭的地形梯度非常适合研究持久性农药和其他有机污染物从低海拔到高海拔的传输情况。2006年春秋两季，沿着卧龙自然保护区巴朗山东坡，在海拔2636米至4479米的五个高度采集了25份土壤样本。土壤提取物通过气相色谱 - 高分辨率质谱法进行分析。六氯苯（HCB）、六氯环己烷（HCH）以及二氯二苯三氯乙烷及其降解产物（滴滴涕）的含量为几纳克/克，而在土壤中仅检测到两种含量低于1纳克/克的轻质多氯联苯同系物。所有分析物的土壤浓度均随海拔显著且呈指数增加。浓度增加速率通过浓度对数与海拔之间线性回归的斜率定量表示，沿六氯苯＜多氯联苯＜六氯环己烷＜或 = 滴滴涕的顺序增加。这一趋势与基于降水清除对温度的依赖性的山地冷阱机制一致，因此为其提供了额外的观测支持。
