| 曹倩茹,罗佳仪,农心怡,周文龙,吴晓妮,付登高.柴河流域农业沟渠系统底泥磷空间分布与流失风险[J].农业环境科学学报,2026,45(5):1248-1257. |
| 柴河流域农业沟渠系统底泥磷空间分布与流失风险 |
| Spatial distribution and release risk of phosphorus in the sediment of agricultural ditch systems in the Chaihe River basin |
| 投稿时间：2025-03-30 |
| DOI：10.11654/jaes.2025-0305 |
| 中文关键词: 底泥磷 磷形态 磷流失风险 面源污染 柴河流域 |
| 英文关键词: sedimentary phosphorus phosphorus speciation phosphorus loss risk non-point source pollution Chaihe River basin |
| 基金项目:国家自然科学基金项目（42267051，32460319） |
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| 摘要点击次数: 20 |
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| 中文摘要: |
| 柴河流域是滇池农业磷素输入的主要来源，其沟渠-河道系统在磷迁移过程中起着关键通道作用。为揭示底泥磷在动态输移过程中的空间分异特征与源汇功能，并定量解析从农田至河道不同空间点位的底泥磷积累与迁移规律，本研究于2021年雨季(8月)沿柴河流域径流路径布设11个典型点位，涵盖大棚农田/沟渠、露天农田/沟渠、二级沟渠及河道等类型。采用传统分级提取法测定底泥全磷(TP)、有效磷(Olsen-P)及无机磷组分(Fe-P、Al-P、Ca-P、O-P)，结合磷活化系数(PAC)和风险评价指数(R)评估磷释放风险，通过空间尺度分析明确其源汇功能。结果表明：不同农田利用方式下土壤磷素水平差异显著，大棚农田土壤TP (4.8 g·kg-1)与Olsen-P (483.20 mg·kg-1)均显著高于露天农田(TP 3.6 g·kg-1，Olsen-P 322.14 mg·kg-1)，但其对应沟渠底泥TP (2.5 g·kg-1)与Olsen-P (191.75 mg·kg-1)却低于露天沟渠(TP 4.7 g·kg-1，Olsen-P 545.51 mg·kg-1)，表明大棚覆盖有助于减少径流携磷量；沿输移路径(S1农田→S9湿地)，底泥TP与Olsen-P呈先升高后降低趋势，峰值出现在河道上游段(S5~S7：TP 4.0 g·kg-1，Olsen-P 471.70 mg·kg-1)；无机磷占TP比例介于55%~86%，其中河道底泥中Ca-P占比高达62%~74%，R在0.35~1.03之间，释放风险较高；PAC与风险评估显示，农田源头区(尤其是露天种植区沟渠)以及柴河上游农业种植区段河道底泥为磷流失的主要“源”，而湿地附近河道底泥表现出潜在的“汇”功能。综上，大棚种植通过减少径流间接降低了沟渠磷累积，露天农田沟渠因颗粒态磷输入成为高风险的磷“源”。输移路径中不同景观类型导致底泥磷呈现先升后降的空间分异。建议农田面源污染控制优先拦截露天农田的颗粒态磷、优化大棚区域磷肥施用比例，并扩建湿地生态屏障以增强其“汇”功能。 |
| 英文摘要: |
| The Chai River basin is a major contributor of agricultural phosphorus inputs to Dianchi Lake, and its ditch-stream network serves as a critical pathway for phosphorus migration. To elucidate the spatial heterogeneity and source-sink functions of sediment phosphorus during dynamic transport and to quantify the patterns of phosphorus accumulation and migration at different positions from farmland to river channels, this study established 11 representative sampling sites along the runoff pathway in the Chai River basin during the rainy season(August)of 2021. These sites encompassed greenhouse farmland/ditches, open-field farmland/ditches, secondary ditches, and river channels. Total phosphorus(TP), Olsen-P, and inorganic phosphorus fractions(Fe-P, Al-P, Ca-P, and O-P)in sediments were determined using conventional sequential extraction methods. The phosphorus activation coefficient(PAC)and risk assessment index(R) were employed to evaluate phosphorus release risk, and the source-sink functions were identified through spatial analysis. The results showed that soil phosphorus levels differed markedly between cultivation types: TP(4.8 g·kg-1)and Olsen-P(483.20 mg·kg-1)in greenhouse farmland soils were significantly higher than those in open-field farmland soils(TP 3.6 g·kg-1, Olsen-P 322.14 mg·kg-1). However, the corresponding ditch sediments in greenhouse areas had lower TP(2.5 g·kg-1)and Olsen-P(191.75 mg·kg-1)than those in open-field ditches(TP 4.7 g·kg-1, Olsen-P 545.51 mg·kg-1), indicating that greenhouse covering helps reduce the amount of phosphorus carried by runoff. Along the transport pathway(from site S1 farmland to S9 wetland), sediment TP and Olsen-P exhibited an initial increase followed by a decrease, with peak values observed in the upper river reaches(S5-S7: TP 4.0 g·kg-1, Olsen-P 471.70 mg·kg-1). Inorganic phosphorus accounted for 55%-86% of TP, and in river sediments Ca-P constituted as much as 62%-74%; the risk index R ranged from 0.35 to 1.03, suggesting a relatively high release risk. The phosphorus activation coefficient and risk assessment revealed that the farmland source areas(especially ditches in open-field cultivation zones)and the river sediments in the upper agricultural reaches of the Chai River functioned as the main“sources”of phosphorus loss, whereas the river sediments near the wetland displayed a potential “sink”function. In conclusion, greenhouse cultivation indirectly reduced phosphorus accumulation in ditches by curtailing runoff, whereas open-field farmland ditches became high-risk phosphorus“sources”due to particulate phosphorus inputs. Different landscape types along the transport pathway resulted in a spatial differentiation of sediment phosphorus characterized by an initial rise and subsequent decline. It is recommended that agricultural non-point source pollution control prioritize the interception of particulate phosphorus from open-field farmlands, optimize phosphorus fertilizer application rates in greenhouse areas, and expand wetland ecological barriers to strengthen their “sink”function. |
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