辽河保护区退耕封育措施消减污染物入河量估算

为了定量评估辽河保护区退耕封育措施在控制面源污染方面的作用,利用高分辨率遥感影像分析了2010—2018年辽河保护区农田面积变化,并基于源强系数法估算了各年农田地表径流污染物入河量。结果显示:2010年辽河保护区河流两岸分布着大量农田,面积约为627.13 km²,占辽河保护区总面积的33.55%,农田地表径流COD和NH₃-N入河量分别为1 864.79和372.96 t/a;2011年随着退耕封育措施的实施,农田面积降为155.63 km²,约减少了75.18%,仅零散分布于河流两岸,农田地表径流COD和NH₃-N入河量减至419.55和83.91 t/a;2012—2018年农田面积和地表径流污染物入河量与2011年基本持平;与2010年相比,2011—2018年退耕封育措施累积消减农田地表径流COD和NH₃-N入河量分别为11 734.49和2 346.90 t。

Estimation of pollutants into river reduced by measures of returning cropland to enclosure in Liaohe Conservation Area

To quantitatively estimate the effect of returning cropland to enclosure on non-point source pollution in Liaohe Conservation Area, the dynamic change of cropland from 2010 to 2018 was analyzed by using high-resolution remote sensing data, and the inflow of pollutants from cropland area surface runoff was estimated by employing the method of source intensity coefficient. The results showed that lots of croplands distributed on both sides of the river in 2010, with an area of about 627.13 km2, accounting for 33.55% of the total area. The COD and NH3-N inflows from cropland surface runoff were 1 864.79 and 372.96 t/a in 2010, respectively. With the measure of returning cropland to enclosure being taken, the cropland area decreased to 155.63 km2 in 2011, with the rate about 75.18%, and only scattered on both sides of the river. The COD and NH3-N inflows from cropland surface runoff decreased to 419.55 and 83.91 t/a, respectively. From 2012 to 2018, the cropland area and the inflow of surface runoff pollutants were generally consistent with that in 2011. Compared with that in 2010, the measures of returning cropland to enclosure reduced the COD and NH3-N inflows from farmland surface runoff by 11 734.49 and 2 346.90 t, respectively, from 2011 to 2018.