Zhang Xuan, Lin Chunye, Zhou Xueli, Lei Kai, Guo Bobo, Cao Yuanxin, Lu Shuang, Liu Xitao, He Mengchang
State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, China.
State Key Joint Laboratory of Environmental Simulation and Pollution Control, School of Environment, Beijing Normal University, Beijing 100875, China.
Sci Total Environ. 2019 Sep 10;682:523-531. doi: 10.1016/j.scitotenv.2019.05.224. Epub 2019 May 18.
Plateau lakes are typically dystrophic and are sensitive to small changes in nutrient deposition. With this assumption, we investigated the concentrations, fluxes, and sources of nitrogen (N) and phosphorus (P) in the atmospheric wet deposition (AWD) of the Lake Qinghai Watershed (LQW), which is the largest inland lake in China, for one year from October 2017 to September 2018. The results showed that the annual volume-weighted mean (VWM) concentrations (mg L) in the AWD were 1.97 for NH-N, 0.55 for NO-N, 0.04 for NO-N, 0.77 for dissolved organic N (DON), 3.33 for total dissolved N (TDN), 0.30 for dissolved inorganic P (DIP), 0.07 for dissolved organic P (DOP), 0.36 for total dissolved P (TDP), and 0.99 for reactive sulfur (SO-S). The annual AWD fluxes of TDN and TDP were 16.82 and 1.86 kg ha yr, respectively. Strong dilution effects in the wet season, a long residency time of nutrient-rich aerosols in the dry season, strong ammonia volatilization in the wet and warm seasons, and moisture sources dominated the seasonal or monthly changing characteristics of N and P concentrations in the AWD, including high in the wet season and low in the dry season for NH-N, low in the wet season and high in the dry season for NO-N, and generally increasing from April to September for DIP and DOP. Precipitation quantity dominated the monthly changes in the N and P fluxes of the AWD, which gradually increased from April to August and then decreased in September. N and P in the AWD mostly originated from anthropogenic sources. High ammonia volatilization from local intense animal husbandry, alkaline soils and lakes led to a relatively high NH-N concentration compared with other sites of the Qinghai-Tibet Plateau, China, and in the world. The N/P molar ratio in the precipitation was higher than 16, which might have effect on the aquatic ecosystems of Lake Qinghai. Ammonia volatilization fluxes and atmospheric dry deposition fluxes of N and P should be further studied to completely understand the geochemical cycles of N and P in the LQW.
高原湖泊通常营养贫瘠，且对养分沉降的微小变化敏感。基于此假设，我们对中国最大的内陆湖——青海湖流域（LQW）2017年10月至2018年9月期间大气湿沉降（AWD）中的氮（N）和磷（P）的浓度、通量及来源进行了为期一年的调查。结果表明，AWD中各成分的年体积加权平均（VWM）浓度（mg L）分别为：铵态氮（NH-N）1.97、硝态氮（NO-N）0.55、亚硝酸盐氮（NO-N）0.04、溶解有机氮（DON）0.77、总溶解氮（TDN）3.33、溶解无机磷（DIP）0.30、溶解有机磷（DOP）0.07、总溶解磷（TDP）0.36以及活性硫（SO-S）0.99。TDN和TDP的年AWD通量分别为16.82和1.86 kg ha yr。湿季的强烈稀释效应、干季营养丰富气溶胶的长时间滞留、湿季和暖季强烈的氨挥发以及水分来源主导了AWD中N和P浓度的季节或月度变化特征，包括铵态氮湿季高干季低、硝态氮湿季低干季高，以及溶解无机磷和溶解有机磷通常从4月到9月增加。降水量主导了AWD中N和P通量的月度变化，其从4月到8月逐渐增加，9月下降。AWD中的N和P大多源自人为源。与中国青藏高原及世界其他地区相比，当地密集畜牧业、碱性土壤和湖泊导致的高氨挥发使得铵态氮浓度相对较高。降水中的N/P摩尔比高于16，这可能会对青海湖的水生生态系统产生影响。为全面了解LQW中N和P的地球化学循环，应进一步研究N和P的氨挥发通量及大气干沉降通量。
