四川盆地丘陵区农业源甲烷排放时空变异特征及驱动因素

为探讨四川盆地丘陵区农业源CH₄排放特征,采用IPCC排放因子法估算2007—2017年农业源CH₄排放量,运用重心模型、Getis-Ord G^*_i指数检验和PLS-STIRPAT模型,探讨区域CH₄排放的时空变化特征及驱动因素。结果表明:(1)2007—2017年,盆地丘陵区农业源CH₄排放量达(32.52～35.93)万t,其中种植业、畜禽养殖业排放占比分别为44.54%～48.26%和51.75%～55.46%,总排放量呈现出随年限增加而降低的趋势,与养殖业CH₄排放密切相关。(2)2007—2017年,盆地丘陵区农业源CH₄排放重心总体向东北方向迁移; 高排放聚集区主要位于研究区东北部,呈现出扩张的趋势,低排放聚集区主要位于西南部,与高值聚集区呈现出相反的缩减趋势。(3)驱动因素中,总人口、农业从业结构和农业产值结构对农业源CH₄排放起到正向促进作用,城镇化率、单位面积施肥量、人均耕地占有量、人均GDP和农村用电量对农业源CH₄排放起控制作用。其中农业产值结构是推动研究区CH₄增长的重要因素。综上,盆地丘陵区农业源CH₄排放水平较高,时空分布差异变动较小,通过农业生产集约集中规模化可有效降低农业源CH₄的排放量。

Spatiotemporal Variability of Agricultural Methane Emissions in the Hilly Area of Sichuan Basin and Its Driving Factors

In order to understand the characteristics of CH₄ emission from agricultural sources in hilly areas of Sichuan Basin, the method of IPCC was used to measure agricultural CH₄ emission in hilly areas of Sichuan basin from 2007 to 2017, and barycenter model, Getis-Ord G^*_i, PLS-STIRPAT model were used to analyze the spatiotemporal distribution of methane emissions and its major driving factors. The results show that:(1)the agricultural CH₄ emissions in the hilly area of Sichuan Basin was up to(3.252～3.593)×10⁵ tons in 2007—2017; the sources of crop farming and livestock and poultry industry accounted for 44.54%～48.26% and 51.75%～55.46%, respectively; the agricultural CH₄ emissions showed a decrease trend, and this may be related to the decrease of CH₄ emissions from the livestock and poultry industry;(2)the barycenter of agricultural CH₄ emission tended to move to the northeast finally along with increasing time; the high CH₄ emission gathering area was mainly located in the northeast, showed an expanding trend, and its high emissions increased significantly over time; on the contrary, the low CH₄ emission gathering area was mainly located in the southwest, showed an opposite trend;(3)the total population, agricultural employment structure, and agricultural output structure played the positive role in agricultural CH₄ emissions; the urbanization rate, fertilization amount per unit area, arable land occupation per capita, GDP per capita, and rural electricity consumption showed the negative effect on agricultural CH₄ emissions; the agricultural output structure was the most important factor that promoted the agricultural CH₄ emissions in the study area. In summary, the CH₄ emission level of agricultural methane emission in hilly areas of Sichuan basin is relatively high, and the difference of spatio-emporal distribution changes little. The agricultural methane emission can be effectively reduced through the intensive and centralized scale of agricultural production.