Water management and aquatic ecosystem services of a tropical reservoir (Itaparica,São Francisco,Brazil)

Reservoirs have a wide variety of uses that have led to frequent conflicts over ecological conservation and contamination, especially as land management has intensified. Oligotrophication must be implemented in numerous tropical reservoirs that experience advanced eutrophication to maintain aquatic ecosystem functions. To quantify impacts on ecosystem functions and to develop an adaptive management policy, multiple studies have been conducted on the Itaparica Reservoir, São Francisco River, in the semi-arid north-eastern region of Brazil. Here, we add to that existing body of knowledge through investigating how nutrient accumulation is affected by water exchange between the main river flow and Icó-Mandantes Bay. Operational water-level fluctuations in the reservoir create large desiccated littoral areas that release high amounts of nutrients when they are rewetted. In particular, water-level variation promotes proliferation of Egeria densa, a noxious weed, thus elevating trophic levels of the Itaparica Reservoir and Icó-Mandantes Bay. Analysis with a P efficiency model determined 25 μg P L^?1 to be the critical concentration and further indicated that the critical load in both bodies of water have been exceeded. Moreover, intensive fish aquaculture using net cages has led to further overtaxing of the reservoir. We conclude that an effective ecological reservoir management policy must involve oligotrophication, harvesting of noxious water weeds for use as soil amendment in agriculture or biogas production, “blue” aquaculture, and limiting hydroelectric power production based on current water availability.     

Growth impact of O3, NO2 and/or SO2 on pinus taeda

Seedlings of two full-sib families of loblolly pine expressing different degrees of sensitivity to O₃ were exposed to 0.05 ppm O₃, 0.10 ppm NO₂, and/or 0.14 ppm SO₂ for 6 hr/day for 28 consecutive days. The treatments were O₃, NO₂, SO₂ (each used alone), O₃+SO₂, O₃+NO₂, and O₃+NO₂+SO₂. Significant growth suppressions were noted with the relatively sensitive family in all but the the NO₂ alone treatments. The O₃+SO₂ treatment had a more significant effect than O₃ alone, but adding NO₂ had an inconsistent effect. Significant growth suppressions were noted for the relatively non-sensitive family only in the O₃+SO₂ and O₃+SO₂+NO₂ combination treatments. Adding NO₂ to O₃+SO₂ had a slightly stimulatory effect. The relatively sensitive pine family suffered a 30% height growth suppression versus a 14% height growth suppression for the relatively insensitive family when exposed to the 3 pollutant combination. Symptoms were noted on less than 4% of the foliage in the most severe treatments. The pollutant concentrations used in this study were below the National Ambient Air Quality Standards (NAAQS) for each pollutant.     

Prediction of effluent arsenic concentration of wastewater treatment plants using machine learning and kriging-based models

Environmental Science and Pollution Research - This study evaluates the potential of kriging-based (kriging and kriging-logistic) and machine learning models (MARS, GBRT, and ANN) in predicting the...     

Applicability of Literature Values for Green–Ampt Parameters to Account for Infiltration in Hydrodynamic Rainfall–Runoff Simulations in Ungauged Basins

Environmental Modeling & Assessment - This study aimed to evaluate the suitability of literature parameter values for the Green–Ampt infiltration model to be used in hydrodynamic...