Carro Marco Mijangos, Dávila Jorge Izurieta, Balandra Antonieta Gómez, López Rubén Hernández, Delgadillo Rubén Huerto, Chávez Javier Sánchez, Inclán Luís Bravo
Department of Hydrobiology and Environmental Assessment, Mexican Institute for Water Technology, Paseo Cuauhnáhuac 8532, Progreso, Jiutepec 62550, México.
Water Sci Technol. 2008;58(11):2179-86. doi: 10.2166/wst.2008.820.
In the catchment area of the Lake Patzcuaro in Central Mexico (933 km2) the apportionments of erosion, sediment, nutrients and pathogen coming from thirteen micro basins were estimated with the purpose of identifying critical areas in which best management practices need to be implemented in order to reduce their contribution to the lake pollution and eutrophication. The ArcView Generalized Watershed Loading Functions model (AV-GWLF) was applied to estimate the loads and sources of nutrients. The main results show that the total annual contribution of nitrogen from point sources were 491 tons and from diffuse pollution 2,065 tons, whereas phosphorus loads where 116 and 236 tons, respectively during a thirty year simulation period. Micro basins with predominant agricultural and animal farm land use (56% of the total area) accounts for a high percentage of nitrogen load 33% and phosphorus 52%. On the other hand, Patzcuaro and Quiroga micro basins which comprise approximately 10% of the total catchment area and are the most populated and visited towns by tourist 686,000 people every year, both contributes with 10.1% of the total nitrogen load and 3.2% of phosphorus. In terms of point sources of nitrogen and phosphorus the last towns contribute with 23.5% and 26.6% respectively. Under this situation the adoption of best management practices are an imperative task since the sedimentation and pollution in the lake has increased dramatically in the last twenty years.
在墨西哥中部帕茨夸罗湖的集水区（933平方公里），估算了来自13个微流域的侵蚀、沉积物、养分和病原体的分配情况，目的是确定关键区域，以便实施最佳管理措施，减少这些区域对湖泊污染和富营养化的影响。应用ArcView通用流域负荷函数模型（AV-GWLF）估算养分的负荷和来源。主要结果表明，在30年的模拟期内，点源氮的年总贡献量为491吨，面源污染氮的年总贡献量为2065吨，而磷的负荷分别为116吨和236吨。以农业和畜牧用地为主的微流域（占总面积的56%），氮负荷占比高达33%，磷负荷占比为52%。另一方面，帕茨夸罗和基罗加微流域约占集水区总面积的10%，是人口最多、游客到访量最大的城镇（每年68.6万人），二者的氮负荷占总量的10.1%，磷负荷占3.2%。就氮和磷的点源而言，这两个城镇的贡献率分别为23.5%和26.6%。在这种情况下，由于湖泊的沉积和污染在过去二十年中急剧增加，采用最佳管理措施势在必行。
