Temporal changes in the hydrology and nutrient concentrations of a large tropical river: Anthropogenic influence in the Lower Grijalva River, Mexico

Periodo de realización: 1900/01/01 al 2018/06/01

Tipo: Artículo científico

Lugar(es) de estudio: Villahermosa, Tabasco, Mexico
Resumen: "Dam construction and nutrient loading are among the greatest threats to freshwaterecosystems, altering ecological processes and the provisioning of ecosystem services.Temporal change in hydrology and ambient nitrogen and phosphorus concentrationswas studied on the Grijalva, a large tropical river in southern Mexico, where fourhydroelectric dams operate and where land conversion has impacted the freshwaterenvironment. Temporal changes in discharge and in river chemistry were examinedby analysing long-term discharge and nutrient data using the software Indicators ofHydrologic Alteration and Mann–Kendall tests. Furthermore, additional water chemistrysamples were collected to examine seasonal nutrient dynamics in the lowerGrijalva. Long-term discharge data indicated dam construction has severely alteredtemporal patterns in discharge and other hydrological characteristics. The lowerGrijalva has also experienced increase in nitrate concentrations through time, whichmay be attributed to the expansion of agricultural and urban areas in the watershed.In contrast, total phosphorus appeared to decline at the sites influenced by damconstruction. Lower nutrient concentrations were recorded upstream from the cityof Villahermosa, suggesting that inputs from urban areas may have contributed tonutrient loading. Additionally, higher nitrate and total phosphorus concentrationswere detected in tributaries draining intensive agricultural and suburban areas. Collectively,the results from the study suggest that dam construction and land conversionin large, tropical watersheds can produce chemical and hydrological changes, whichmay negatively impact important ecosystem services—such as fisheries and theprovisioning of sources of drinking water—and may compromise the integrity ofcoastal zones."

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