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对位于重庆铁山坪的马尾松林下的山地黄壤进行表层土壤(0~5 cm)的原状采集,并在实验室中进行控制实验,利用通量箱法测量原状土块表面的汞释放通量,以研究环境因子对土壤汞释放量的影响.结果表明,土壤汞释放量与辐射强度呈显著的正相关,在相同的空气温度和土壤含水量等条件下,土壤汞释放量在光下是遮阳条件下的3~9倍.不过,由于林下土壤常处于背阴状态,可能遮阳条件更能代表白天林下土壤汞的排放情况.土壤汞释放量存在明显的季节变化,夏季>春秋季>冬季,空气温度与土壤汞释放呈正相关.在低温下土壤汞释放量很低,土壤含水量影响较弱,而在高温时土壤含水量增加能明显促进土壤汞释放.枯落物的移除会显著降低土壤汞释放通量,主要原因可能是枯落物的汞含量较高并易于还原.土壤汞释放量在一天内也存在明显的衰减趋势,表明土壤表层的汞含量可能是森林土壤汞释放的重要限制因素.本研究测得森林土壤汞释放通量(白天)为:夏季(14.3±19.6)ng·(m2·h)-1、春秋季(3.50±5.36)ng·(m2·h)-1、冬季(1.48±3.27)ng·(m2·h)-1,以上稳态测试结果可能高估了实际的汞排放量.
The yellow soil of Pinus massoniana forest located in Tieshanping of Chongqing was sampled from the surface soil (0 ~ 5 cm) and controlled experimentally in the laboratory. The mercury fluxes on the surface of undisturbed soil were measured by the flux box method To study the effect of environmental factors on soil mercury release.The results showed that there was a significant positive correlation between soil mercury release and radiation intensity.Under the same conditions of air temperature and soil moisture, However, as the undergrowth soil is often in the shade state, it is possible that the shade condition can better represent the mercury emission in the soil under daytime forest. The release of mercury in the soil has obvious seasonal changes in summer> spring and autumn> In winter, the air temperature was positively correlated with the release of mercury in soil, and the release of mercury in soil was very low at low temperature, and the soil water content had little effect on the air temperature, while the increase of soil water content at high temperature could significantly promote the release of mercury in soil. Significantly reduce the soil mercury release flux, the main reason may be litter mercury content is high and easy to reduce. Soil mercury release in the day there is also a clear decay trend, indicating that the surface of the soil mercury content Is the important limiting factor of mercury release in forest soils.The measured mercury fluxes in the soil were (14.3 ± 19.6) ng · (m 2 · h) -1 in summer and (3.50 ± 5.36) ng · (m2 · h) -1 and winter (1.48 ± 3.27) ng · (m2 · h) -1, the above steady-state test results may overestimate the actual mercury emissions.