摘要:在当前城镇化持续推进的背景下, 探究我国城镇化对化肥面源污染的作用机制, 对缓解我国生态压力, 促进农业绿色高质量发展具有重要现实意义。鉴于此, 本文基于2008—2018年城镇化和化肥施用量等省际面板数据, 运用单元调查评估法测算2008—2018年31个省(市、自治区)化肥面源污染物排放总量及排放强度, 再运用中介效应模型探究城镇化对化肥面源污染的影响机制。结果表明: 1) 2008—2018年我国化肥面源污染排放呈现先增后降的倒“U”型特征, 以2015年为拐点, 到研究期末排放总量及强度均降至该时期最低水平, 分别为516万t和37.65 kg·hm?2。2)从全国层面看, 城镇化会通过技术进步、劳动力转移、农地禀赋对化肥面源污染产生中介影响, 其中农地禀赋中介效应绝对值最大(0.0092), 劳动力与技术进步趋近, 分别为0.0040和0.0033。3)城镇化对化肥面源污染的影响机制存在显著的空间异质性。从技术进步看, 粮食主销区的中介效应绝对值最大(0.0160), 粮食主产区次之(0.0118), 粮食产销平衡区无显著中介效应; 从劳动力看, 仅粮食主产区存在显著中介效应(0.0538); 从农地禀赋看, 粮食主销区的中介效应绝对值最大(0.0126), 粮食产销平衡区次之(0.0095), 粮食主产区最小(0.0055), 其中粮食产销平衡区的中介效应方向与其他地区相反。为此, 在粮食主销区应重点加强耕地保护, 加快制定跨区协作的“占补平衡”制度, 在粮食主产区应积极引导优质劳动力回流农业部门, 在粮食平衡区应加快绿色农业技术与管理模式的应用。
关键词:城镇化/
面源污染/
中介效应模型/
粮食功能区/
空间异质性
Abstract:In the light of continued urbanization, it is important to analyze the effect of urbanization on fertilizer non-point source pollution in China to alleviate ecological pressure and promote green and high-quality agriculture development. This study used the unit survey and assessment method to measure the total emissions and emission intensity of fertilizer non-point source pollution in 31 provinces (cities, autonomous regions) in China from 2008 to 2018. The mediation effect model was used to analyze the influence of urbanization on fertilizer non-point source pollution. Compared with existing studies, this study has two aims. The first is to analyze the influence of urbanization on fertilizer non-point source pollution via the mediation effect, and to clarify the mechanism of how urbanization affects fertilizer non-point source pollution. The second is to analyze the spatial heterogeneity in the impact of urbanization on the fertilizer non-point source pollution in grain function areas, e.g., differences in the mechanisms of various mediation factors in different grain function areas. Our empirical results showed that: 1) from 2008 to 2018, fertilizer non-point source pollution in China had an inverted “U” pattern, first increasing and then decreasing, with 2015 as the inflection point. The total amount and intensity of emissions fell to the lowest levels at the end of the study period, 5.16 million t and 37.65 kg·hm?2, respectively. 2) On a national level, urbanization had a mediating effect on fertilizer non-point source pollution owing to technological progress, labor migration, and farmland endowment. The mediation effect of farmland endowment had the highest absolute value (0.0092), and the mediation effects of labor and technological progress were increasing to 0.0040 and 0.0033, respectively. 3) There was significant spatial heterogeneity in the influence of urbanization on fertilizer non-point source pollution. For technological progress, the absolute value of the mediation effect in the major grain-consuming areas was the highest (0.0160), followed by that in the major grain-producing areas (0.0118), whereas the grain-balance areas did not have a significant mediation effect. For labor, there was only a significant mediation effect in the major grain-production areas (0.0538). For farmland endowment, the absolute value of the mediation effect in the major grain-consuming areas was the highest (0.0126), followed by that in the grain-balance areas (0.0095), and the major grain-producing areas had the lowest absolute value (0.0055). The direction of the mediation effect in grain-balance areas was opposite to that in other regions. Therefore, it was important to protect arable land in the major grain-consuming areas and to form a cross-regional collaboration system of “occupation-compensation balance”. In the major grain-producing areas, high-quality labor should be actively guided to return to the agricultural sector. In the grain-balance areas, green agricultural technology and management modes should be introduced.
Key words:Urbanization/
Non-point source pollution/
Mediation effect model/
Food functional area/
Spatial heterogeneity
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