Department of Biological and Agricultural Engineering, Texas A&M University, College Station, TX 77843-2117, USA.
J Air Waste Manag Assoc. 2011 Jul;61(7):786-95. doi: 10.3155/1047-3289.61.7.786.
Greenhouse gas (GHG) emissions from agricultural production operations are recognized as an important air quality issue. A new technique following the U.S. Environmental Protection Agency Method TO-14A was used to measure GHG emissions from ground-level area sources (GLAS) in a free-stall dairy operation in central Texas. The objective of this study was to quantify and report GHG emission rates (ERs) from the dairy during the summer and winter using this protocol. A weeklong sampling was performed during each season. A total of 75 and 66 chromatograms of air samples were acquired from six delineated GLAS (loafing pen, walkway, barn, silage pile, settling basin, and lagoon) of the same dairy during summer and winter, respectively. Three primary GHGs--methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O)--were identified from the dairy operation during the sampling periods. The estimated overall ERs for CH4, CO2, and N2O during the summer for this dairy were 274, 6005, and 7.96 g head(-1)day(-1), respectively. During the winter, the estimated overall CH4, CO2, and N2O ERs were 52, 7471, and 3.59 g head(-1)day(-1), respectively. The overall CH4 and N2O ERs during the summer were approximately 5.3 and 2.2 times higher than those in the winter for the free-stall dairy. These seasonal variations were likely due to fluctuations in ambient temperature, dairy manure loading rates, and manure microbial activity of GLAS. The annualized ERs for CH4, CO2, and N2O for this dairy were estimated to be 181, 6612, and 6.13 g head(-1)day(-1), respectively. Total GHG emissions calculated for this dairy with 500 cows were 2250 t of carbon dioxide equivalent (CO2e) per year.
农业生产作业产生的温室气体（GHG）排放被认为是一个重要的空气质量问题。美国环保署方法 TO-14A 之后的一项新技术被用于测量德克萨斯州中部一个自由式奶牛场的地面区域源（GLAS）的 GHG 排放。本研究的目的是使用该协议量化和报告奶牛场夏季和冬季的 GHG 排放率（ER）。每个季节进行了为期一周的采样。在夏季和冬季，分别从同一家奶牛场的六个划定的 GLAS（休息室、走道、谷仓、青贮堆、沉降池和泻湖）采集了总共 75 和 66 个空气样本的色谱图。在采样期间，从奶牛场作业中确定了三种主要的 GHG——甲烷（CH4）、二氧化碳（CO2）和氧化亚氮（N2O）。在夏季，该奶牛场的 CH4、CO2 和 N2O 的总估计排放率（ER）分别为 274、6005 和 7.96 g 头-1 day-1。在冬季，CH4、CO2 和 N2O 的总估计 ER 分别为 52、7471 和 3.59 g 头-1 day-1。夏季的总 CH4 和 N2O ER 分别比冬季自由式奶牛场高约 5.3 倍和 2.2 倍。这种季节性变化可能是由于环境温度、奶牛粪便负荷率和 GLAS 中粪便微生物活性的波动造成的。该奶牛场的 CH4、CO2 和 N2O 的年化 ER 估计分别为 181、6612 和 6.13 g 头-1 day-1。拥有 500 头牛的该奶牛场的总 GHG 排放量估计为每年 2250 吨二氧化碳当量（CO2e）。
