大气沉降向华中丘陵区稻田输入硫通量的观测

选取我国华中丘陵区的湖南省长沙县一个典型水稻种植区，对2015与2016年2年雨水样中的SO₄²-S和大气SO₂的沉降量进行监测，分析雨水中SO₄^2-、NO₃^-的关系，解析大气硫沉降的主要来源.结果表明，研究区大气中SO₂-S和雨水中SO₄^2--S的年均浓度分别为8.5 μg/m³和1.1mg/L，大气硫沉降年均总量为26.8kgS/（hm²·a），其中年均降雨混合沉降量18.2kgS/（hm²·a），年均干沉降量为8.6kgS/（hm²·a）.研究区域硫素干、混合沉降量存在明显的季节差异，硫素混合沉降春季高于夏、秋、冬季，而硫素干沉降冬季高于春、夏、秋季.雨水中NO₃^-/SO₄^2-的质量比大多小于1，表明研究区大气硫素主要来自固定污染源（燃煤）.华中丘陵区稻田具有较高的硫沉降，但硫沉降量已较21世纪初出现了较大幅度下降，农业生产中需要根据农田硫素收支状况酌情补充硫肥来保证作物高产稳产.

Atmospheric sulfur deposition in a paddy rice region in the hilly region in central china

This study measured atmospheric bulk and dry sulfur depositions in 2015 and 2016 in a paddy rice region in the hilly region in central China, analyzed the relationship between SO₄^2- and NO₃^- in rainwater, and explored the sources of atmospheric sulfur compounds. The annual average concentrations of SO₂-S in the atmosphere and SO₄^2--S in the rain water in the study region were 8.5μg/m³ and 1.8mg/L, respectively. The annual average of the total sulfur deposition was 26.8kgS(hm²·a), with the annual average of bulk deposition of 18.2kgS(hm²·a), and the annual average of dry deposition of 8.6kgS(hm²·a). There were significant seasonal variations in the sulfur bulk and dry depositions. The sulfur bulk deposition in spring was the highest, while the sulfur dry deposition in winter was the highest among the seasons. The mass ratio of NO₃^-/SO₄^2- in the rainwater was less than 1in most of the months, indicating that the primary source of the atmospheric sulfur compounds was the stationary pollution source (coal burning) in the study region. There was relatively high sulfur deposition in the paddy rice regions in the hilly region in central China in the studied period, but the sulfur deposition had been decreased largely as compared to those measured in early 2000s. Thus, sulfur fertilizers need to be used in the croplands in this region based on the soil sulfur balance status, so as to keep high yields of crops.