Gu Pei, Shen Ren Fang, Chen Yi Ding
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Environ Sci Pollut Res Int. 2008 May;15(3):273-7. doi: 10.1065/espr2007.07.438.
The Yangtze Delta is one of the most developed regions in China and includes Shanghai, eight cities in Jiangsu province and eight cities in Zhejiang province. Meat consumption in this region has increased with economic growth, and most of the consumed meat is produced locally. The water quality of surface waters has deteriorated in recent years. An example was the huge blue-green algae bloom in Tai Lake in late May 2007, which affected millions of people's daily drinking water. However, animal husbandry is considered to be one of the main pollution sources.
Pollutants (NH3-N, total phosphorus (TP), and total nitrogen (TN)) excreted by livestock and poultry, and the resultant COD (chemical oxygen demand) and BOD (biochemical oxygen demand), were estimated using two different methods based on different data sets.
The number of livestock and poultry has remained stable in the Yangtze Delta over the four years from 1999 to 2002, with the average number of pigs, cattle, sheep and poultry being 21.1 M, 0.4 M, 7.7 M and 597.6 M, respectively. Pollutants in livestock and poultry excreta estimated by Method I were: 0.12 Mt NH3-N, 0.11 Mt TP and 0.29 Mt TN, resulting in COD and BOD of 1.34 Mt and 1.30 Mt, respectively, while the estimations based on Method II were: 0.18 Mt NH3-N, 0.15 Mt TP and 0.40 Mt TN, resulting in COD and BOD of 1.95 Mt and 1.80 Mt, respectively.
Pollutants excreted annually by livestock and poultry in the Yangtze Delta are estimated to be: 0.17 Mt NH3-N, 0.16 Mt TP and 0.42 Mt TN, giving rise to a COD of 1.86 Mt and a BOD of 1.72 Mt. Approximately 25% of this pollution was estimated to enter water bodies, which means that the annual pollutant load is 43,700 t NH3-N, 39,400 tTP, 104,600t TN with a COD of 465,000 tand a BOD of 430,100 t. Pollutants from animal husbandry were similar in magnitude to those from industrial wastewater. Pigs produced the most pollution, followed by poultry, cattle and sheep. The pollution load from animal husbandry in the Yangtze Delta is about twice the average level of the whole of China.
Domestic wastewater was the main pollution source in the Yangtze Delta, followed by pollution from raising livestock and poultry and from industrial wastewater. The pollution load in Shanghai and Jiaxing were the greatest, followed by 7 cities of Jiangsu province (except Suzhou) and other cities of Zhejiang province and Suzhou. Pigs and poultry produced about 90% of the total pollutants from animal husbandry.
The local governments, especially in Shanghai and Jiaxing, should focus their attention on the pollution produced by livestock and poulrry. Controlling pollution from pigs and poultry will have the greatest impact in this region. Control of pollution will be facilitated by the development of large-scale livestock and poultry farming units and a shift away from small scale husbandry.
长江三角洲是中国最发达的地区之一，包括上海、江苏省的八个城市和浙江省的八个城市。该地区的肉类消费随着经济增长而增加，且大部分消费的肉类是本地生产的。近年来，地表水水质恶化。例如，2007年5月底太湖发生的大规模蓝藻爆发，影响了数百万人的日常饮用水。然而，畜牧业被认为是主要污染源之一。
基于不同数据集，使用两种不同方法估算畜禽排放的污染物（氨氮、总磷（TP）和总氮（TN））以及由此产生的化学需氧量（COD）和生化需氧量（BOD）。
1999年至2002年的四年间，长江三角洲地区的畜禽数量保持稳定，猪、牛、羊和家禽的平均数量分别为2110万头、40万头、770万只和5.976亿只。方法I估算的畜禽粪便污染物为：氨氮0.12百万吨、总磷0.11百万吨和总氮0.29百万吨，产生的化学需氧量和生化需氧量分别为1.34百万吨和1.30百万吨，而基于方法II的估算为：氨氮0.18百万吨、总磷0.15百万吨和总氮0.40百万吨，产生的化学需氧量和生化需氧量分别为1.95百万吨和1.80百万吨。
据估计，长江三角洲地区畜禽每年排放的污染物为：氨氮0.17百万吨、总磷0.16百万吨和总氮0.42百万吨，产生化学需氧量1.86百万吨和生化需氧量1.72百万吨。估计约25%的这种污染进入水体，这意味着每年的污染物负荷为43700吨氨氮、39400吨总磷、104600吨总氮，化学需氧量为465000吨，生化需氧量为430100吨。畜牧业的污染物与工业废水的污染物数量相当。猪产生的污染最多，其次是家禽、牛和羊。长江三角洲地区畜牧业的污染负荷约为全国平均水平的两倍。
生活污水是长江三角洲的主要污染源，其次是畜禽养殖污染和工业废水污染。上海和嘉兴的污染负荷最大，其次是江苏省的7个城市（苏州除外）、浙江省的其他城市和苏州。猪和家禽产生了畜牧业总污染物的约90%。
地方政府，特别是上海和嘉兴的政府，应关注畜禽养殖产生的污染。控制猪和家禽的污染将对该地区产生最大影响。大规模畜禽养殖单位的发展和从小规模养殖的转变将有助于控制污染。
