Abstract:

According to the bulletin of the second Chinese national census of pollution sources, 39% and 63% of the nitrogen and phosphorus pollution in Guangdong province were from agricultural non-point source pollution (ANP). ANP has become one of the main causes of water pollution, lake eutrophication, and rural environment deterioration. It is significant to clarify ANP load and its characteristics in each district and county of Guangdong province for the prevention of ANP and ecological environment improvement. Using the data from the Agricultural Statistical Yearbook of Guangdong Province in 2020 and based on the improved export coefficient model, annual and monthly ANP loads and spatio-temporal characteristics were estimated. In addition, the pollution load coefficient per unit area was used to evaluate the degree of impact of ANP on the environment. The results indicated that (1) there were 160.9 kilotons and 17.1 kilotons of TN and TP pollution loads in 2019. The main source was livestock breeding, which contributed to 67.2% and 64.6% of TN and TP emissions. (2) The pollution loads in western Guangdong were larger than those in other regions. The pollution loads were concentrated from April to September, accounting for 60% of the whole year. The annual TN and TP loads in Xinyi, Xinxi, and Gaozhou were the top three largest among all the cities of Guangdong, whereas, Baoan, Foshan downtown, and Longgang had the lowest TN and TP loads in 2019. (3) Due to the agricultural TN and TP emissions, there were serious environmental threats in 35.3% and 40.2% of the districts and counties in Guangdong, including developed areas like Guangzhou and Zhanjiang downtown; 33.3% and 36.3% of districts and counties had no environmental threats from TN and TP emissions. Overall, the ANP load in Guangdong province was large with an uneven spatial and temporal distribution. The agricultural TN and TP loads and their environmental impact in western Guangdong were more serious than those in northern Guangdong, eastern Guangdong, and Pearl River Delta.

Key words: pollution loads, nitrogen and phosphorus pollution, spatio-temporal distribution, pollution levels, plant, livestock and poultry

摘要：

全国第二次污染源普查公报显示,广东省农业面源污染对全省氮磷污染的贡献率分别为39%和63%。农业面源污染成为广东省水体污染、湖泊富营养化和农村环境恶化的主要原因之一,理清全省各区县农业面源污染负荷量和特征对面源污染防治和生态环境改善具有重要意义。基于2020年广东省农业统计年鉴数据,采用改进输出系数法,分析了2019年广东全省102个单位的农业面源污染年和月负荷量及时空分布特征,利用单位面积负荷系数评价了农业面源对环境的影响程度。结果表明：（1）2019年广东省农业面源氮、磷排放量分别为16.09×10⁴ t和1.71×10⁴ t,其中畜禽养殖业贡献较大,其对水体总氮（TN）、总磷（TP）的贡献率分别为67.2%、64.6%。（2）空间上广东省农业氮磷流失主要来源于粤西地区,时间上全省4—9月TN和TP排放量占全年60%。全省TN和TP年排放量最高的3个区县分别是信宜、新兴和高州,年排放量最低的3个区县分别是宝安、佛山市区和龙岗。（3）全省35.3%和40.2%的区县农业TN、TP流失对环境不构成威胁,33.3%和36.3%的区县农业TN和TP流失对环境造成严重威胁,其中包括广州市区、湛江市区等经济发达地区。可见,广东省农业面源污染负荷量大,时空分布不均,粤西地区农业TN、TP负荷量及对环境的影响较粤北、粤东和珠三角地区更严重。

关键词: 污染负荷, 氮磷污染, 时空分布, 污染程度, 种植, 畜禽养殖