重庆市畜禽粪污的区域分布及其水环境响应特征分析

Regional distribution of livestock manure and response characteristics of water environment in Chongqing

  • 摘要: 为解决常见畜禽养殖排污量估算方法存在的缺陷和核实重庆市畜禽养殖目前污染状况, 在调研当地畜禽养殖业及其排放状况的基础上, 提出计算规模化养殖场排污量的校正方法, 核算在现有治污模式下的典型畜禽排污量; 以重庆市五大功能区为研究对象, 基于不同水环境功能区划, 采用等标污染负荷比法, 研究了化学需氧量(CODCr)、总氮(TN)、总磷(TP)等标排放量的功能区分布及其潜在水环境响应特征, 进而确定了畜禽养殖业主要污染区域和主要污染物, 为重庆市不同功能区的产业发展和环境保护提供决策依据。结果表明, 重庆市2013年畜禽养殖量为411.81万猪当量, 粪便、尿、CODCr、TN、TP实物排放量分别为2.27×106 t、1.66×106 t、3.03×104 t、0.72×104 t和1.87×104 t。CODCr、TN、TP等标排放量分别为1.44×109 m3、7.94×109 m3和1.02×1011 m3。主要污染区域为城市发展新区和渝东北生态涵养发展区, 主要污染物为TP, 且重庆市畜禽养殖业的发展与功能区划有着显著相关关系。因畜禽养殖污染引起的全市水环境水质综合指数在0.22~4.12。城市发展新区和渝东北生态涵养发展区的水质超过标准, 其余功能区均未超标。

     

    Abstract: Correct calculations of livestock pollutants discharges are required for determination of the impact of livestock on water environment. The existing estimation methods of livestock pollutants discharges are insufficient and confusing in terms of definition of discharge coefficients, and therefore induce mistakes in breeding cycle calculations and livestock elimination rate. Aiming to meet these problems, the paper established calibration methods for calculating production coefficient and discharge coefficient of pollutants, and breeding cycle of livestock, based on livestock breeding data and pollution control methods of Chongqing City of China. And the producing and discharging amounts of livestock in Chongqing City were estimated with the methods. According to ecological function of five functional areas of Chongqing City and discharge characteristics of chemical oxygen demand (CODCr), total nitrogen (TN) and total phosphorus (TP), the equiscalar pollution loading ratio and comprehensive pollution index were used to investigate regional distribution of livestock manure and water environment response and to identify the main pollutants and polluted areas in Chongqing. The results provided the needed decision support for industrial development and environmental protection. Results showed that the breeding cycles of pig, dairy cattle, beef cattle, laying hens and broilers were 122, 365, 365, 52 and 365 days, respectively. The corresponding discharge coefficients for CODCr were 0.049, 0.626, 0.170, 0.002 and 0.001 kg·head-1·d-1, respectively. Also the corresponding discharge coefficients for TN were 0.013, 0.081, 0.048, 0.001 and 0 kg·head-1·d-1, respectively. Then the corresponding discharge coefficients for TP were 0.012, 0.024, 0.030, 0.001 and 0.003 kg·head-1·d-1, respectively. A total of 411.81×104 equivalent pig heads were raised in 2013 in Chongqing City, and 2.27×106 tons manure, 1.66×106 tons urine and were discharged containing respectively 3.03×104 t, 0.72×104 t and 1.87×104 tons of CODCr, TN and TP. Based on pollution evaluation, the main contaminated areas were urban development area and northeast ecological conservation development area, with TP as the main pollutant. The synthetic index of water potential quality range was 0.22–4.12. The results also showed that the development of livestock breeding was significantly correlated with function regionalization. Water pollution was not the main environmental problem in urban core function area, which was the center of politics, economy and culture defined some sections as “forbidden region for raising livestock”. Urban development area was the main polluted region, where implement industrial planting was promoted in order to solve the contradictions between economic progress and environmental protection. The northeast ecological conservation development area was another main polluted region, where the ecological red lines were needed to build to restrict project implementation and protect the Three Gorges Reservoir.

     

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