Posgrado en Ciencias del Mar y Limnología, Universidad Nacional Autónoma de México, Av. Ciudad Universitaria 3000, 04510, Coyoacán, Ciudad de México, Mexico.
Instituto de Geofísica, Universidad Nacional Autónoma de México, Av. Universidad 3000, 04510, Coyoacán, Ciudad de México, Mexico.
Environ Monit Assess. 2020 Jun 6;192(7):417. doi: 10.1007/s10661-020-08354-7.
This study assessed the spatial and temporal nutrient variability in the El Fuerte River basin in northwestern Mexico, considering its effects on the water trophic status as well as the nutrient loading to the Gulf of California. Physicochemical parameters, inorganic species of nitrogen, phosphate, total nitrogen, total phosphorus, and chlorophyll-a (chl-a) were quantified at 16 selected sites along the river in April (dry season) and October (rainy season) 2017. Mean concentrations of nutrients during dry and rainy seasons were 36.3 ± 24.1 and 55.1 ± 74.6 μg L of total ammonia nitrogen, 3.4 ± 3.6 and 4.5 ± 3.5 μg L of NO-N, 190.8 ± 256.0 and 163.6 ± 261.0 μg L of NO-N, 42.4 ± 44.2 and 104.9 ± 76.2 μg L of PO-P, 1.0 ± 1.3 and 691 ± 2242 mg L of TN, 0.06 ± 0.06 and 0.08 ± 0.09 mg L of TP, and 0.9 ± 0.6 and 2.0 ± 0.9 μg L of chl-a with significant differences (p < 0.05) between sites and seasons. When waters are transported downstream, nutrient levels are enriched by 4 to 35 times compared to those upstream due to increased population and agriculture downstream, confirming the hypothesis of the study. The calculated TN and TP fluxes were 1.23 × 10 and 3.57 × 10 ton year, respectively. Factor analysis indicated that inorganic nitrogen species and phosphorus are the main factors affecting the river water quality. Despite N excess during the rainy season, the river reached mesotrophic waters due to phosphorus limitation. This suggests the need to establish a water quality monitoring program to understand the vulnerability of the river course to changes in its trophic state.
本研究评估了墨西哥西北部埃尔富尔特河流域的时空养分变异性，考虑了其对水营养状态的影响以及对加利福尼亚湾的养分负荷。2017 年 4 月（旱季）和 10 月（雨季）在河流的 16 个选定地点量化了理化参数、无机氮种、磷酸盐、总氮、总磷和叶绿素-a（chl-a）。在旱季和雨季，营养物质的平均浓度分别为 36.3 ± 24.1 和 55.1 ± 74.6 μg L 的总氨氮、3.4 ± 3.6 和 4.5 ± 3.5 μg L 的 NO-N、190.8 ± 256.0 和 163.6 ± 261.0 μg L 的 NO-N、42.4 ± 44.2 和 104.9 ± 76.2 μg L 的 PO-P、1.0 ± 1.3 和 691 ± 2242 mg L 的 TN、0.06 ± 0.06 和 0.08 ± 0.09 mg L 的 TP 和 0.9 ± 0.6 和 2.0 ± 0.9 μg L 的 chl-a，站点和季节之间存在显著差异（p < 0.05）。当水向下游输送时，由于下游人口和农业的增加，养分水平比上游富集了 4 到 35 倍，证实了研究的假设。计算得出的 TN 和 TP 通量分别为 1.23 × 10 和 3.57 × 10 吨年。因子分析表明，无机氮种和磷是影响河水水质的主要因素。尽管雨季存在氮过剩，但由于磷限制，河流仍达到中营养状态。这表明需要建立水质监测计划，以了解河道对其营养状态变化的脆弱性。
