Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO-1234yf
Deposition and rainwater concentrations of trifluoroacetic acid in the United States from the use of HFO-1234yf
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DOI：
10.1002/2014jd022058
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发表时间：
2014-12-27
影响因子：
4.4
通讯作者：
Ravishankara, A. R.
中科院分区：
文献类型：
--
作者：
Kazil, J.;McKeen, S.;Ravishankara, A. R.
目前，HFC-134 a（1，1，1，2-二氯乙烷）是汽车空调中最常用的制冷剂。这种高全球变暖潜势物质（100年全球升温潜能值为1370）可能会被淘汰，并被100年全球升温潜能值为4的HFO-1234 yf（2，3，3，3-二丙烯）取代。HFO-1234 yf会在云层中被氧化生成三氟乙酸（TFA）。反式脂肪酸是一种轻度毒性物质，在高浓度（>= 100 μ gL（-1））时对某些水生生物具有有害影响，可通过雨水输送到地表并进入水体。我们研究了干和湿沉积的TFA从HFO-1234 yf在美国本土使用先进的研究天气研究和预报模型（ARW）与交互式化学，气溶胶和云过程（WRF/Chem）模型。特别关注的是来自美国大陆三个具有不同气象特征的地区的排放量。2006年5月至9月，WRF/Chem模拟了气象学、云过程、气相和水相化学以及干和湿沉降。该模型再现以及多个月的总硫酸盐湿沉降（4%的偏差）和空间变异性（r = 0.86）观察到的国家大气沉降计划。HFO-1234 yf的排放量是通过假设汽车空调数量保持不变，并将HFO-1234 yf（摩尔/摩尔）替代HFC-134 a而得出的。我们对当前HFC-134 a排放量的估计与现场数据一致。2006年5月至9月期间，美国邻近地区的平均TFA雨水浓度为0.89 μ gL（-1），峰值为7.8 μ gL（-1）。美国西部干旱地区的反式脂肪酸雨水浓度往往显着较高，但湿沉积反式脂肪酸量仍然相对较低，在这些地点。
Currently, HFC-134a (1,1,1,2-tetrafluoroethane) is the most common refrigerant in automobile air conditioners. This high global warming potential substance (100 year GWP of 1370) will likely be phased out and replaced with HFO-1234yf (2,3,3,3-tetrafluoropropene) that has a 100 year GWP of 4. HFO-1234yf will be oxidized to produce trifluoroacetic acid (TFA) in clouds. TFA, a mildly toxic substance with detrimental effects on some aquatic organisms at high concentrations (>= 100 mu gL(-1)), would be transported by rain to the surface and enter bodies of water. We investigated the dry and wet deposition of TFA from HFO-1234yf over the contiguous USA using the Advanced Research Weather Research and Forecasting model (ARW) with interactive chemical, aerosol, and cloud processes (WRF/Chem) model. Special focus was placed on emissions from three continental USA regions with different meteorological characteristics. WRF/Chem simulated meteorology, cloud processes, gas and aqueous phase chemistry, and dry and wet deposition between May and September 2006. The model reproduced well the multimonth total sulfate wet deposition (4% bias) and its spatial variability (r = 0.86) observed by the National Atmospheric Deposition Program. HFO-1234yf emissions were obtained by assuming the number of automobile air conditioners to remain unchanged, and substituting HFO-1234yf, mole-per-mole for HFC-134a. Our estimates of current HFC-134a emissions were in agreement with field data. Average TFA rainwater concentration was 0.89 mu gL(-1), with peak values of 7.8 mu gL(-1), for the May-September 2006 period over the contiguous USA. TFA rainwater concentrations over the dry western USA were often significantly higher, but wet-deposited TFA amounts remained relatively low at such locations.