Sources of Nitrate in Ground Water Aquifers of the Semiarid Region of Tanzania

Nitrate isotopic values are often used as a tool to identify sources of nitrate in order to effectively manage ground water quality. In this study, the concentrations of NO3−, NO2−, and NH4+ from 50 boreholes and shallow wells in the Singida and Manyoni Districts were analyzed during the dry and wet seasons, followed by identification of nitrate sources using the hydrochemical method (NO3−/Cl−) and stable isotope (δ15N and δ18O) techniques. Results showed that NO2− and NH4+ concentrations were very low in both seasons due to the nitrification process. The concentrations of NO3− ranged from 2.4 ppm to 929.6 ppm with mean values of 118.5 ppm ± 118.5 ppm , during the dry season and from 2.4 ppm to 1620.0 ppm with mean values of 171.6 ppm ± 312.3 ppm , during the wet season. The higher NO3− contamination observed in the wet season could be due to rainfall which accelerated the surface runoff that collects different materials from various settings into the ground water sources. Nitrate source identification through hydrochemical technique revealed that most nitrates originated from sewage effluents and/or organic wastes such as manure. Likewise, the mean values of δ15N-NO3− ( + 20.90 ‰ ± 5.17 ‰ and + 18.30 ‰ ± 6.33 ‰ ) and the mean values of δ18O-NO3−( + 13.86 ‰ ± 3.18 ‰ and + 13.69 ‰ ± 3.97 ‰ ) suggest that 80% of boreholes and 52% of shallow wells were dominated with nitrate from sewage effluents and/or manure as most ground water sources were situated in densely populated areas with congested and poorly constructed onsite sanitation facilities such as pit latrines and manure. Therefore, to reduce nitrate pollution in the study area, a central sewer must be constructed to treat the discharged wastes. Also, groundwater harvesting should consider the proper principles for groundwater harvesting recommended by the respective authority to minimize chances of contamination and hence prevention of health risk.

Microfibers from synthetic textiles as a major source of microplastics in the environment: A review

Microplastic fibers, also known as microfibers, are the most abundant microplastic forms found in the environment. Microfibers are released in massive numbers from textile garments during home laundering via sewage effluents and/or sludge. This review presents and discusses the importance of synthetic textile-based microfibers as a source of microplastics. Studies focused on their release during laundering were reviewed, and factors affecting microfiber release from textiles and the putative role of wastewater treatment plants (WWTPs) as a pathway of their release in the environment were examined and discussed. Moreover, potential adverse effects of microfibers on marine and aquatic biota and human health were briefly reviewed. Studies show that thousands of microfibers are released from textile garments during laundering. Different factors, such as fabric type and detergent, impact the release of microfibers. However, a relatively smaller number of available studies and often conflicting findings among studies make it harder to establish definitive trends related to important factors contributing to the release of microfibers. Even though current WWTPs are highly effective in capturing microfibers, due to the presence of a massive number of microfibers in the influent, up to billions of fibers per day are released through effluent into the environment. There is a need to establish standardized protocols and procedures that can allow meaningful comparisons among studies to be performed.

Functional diversity on rocky shores of the SW Atlantic: sewage effluents influence and mask the effects of the latitudinal gradient

Rocky shores are a transitional ecosystem between land and marine environments, and, together with other benthic coastal habitats, have a diverse macrobenthic community. Although there is enough information about the taxonomic diversity of Argentinean rocky shores, studies with a functional approach are scarce. We applied biological traits analysis and functional diversity indices to evaluate the geographic variation of the functional diversity of macrobenthic assemblages on rocky shores along a latitudinal gradient in the SW Atlantic (from 37° to 50°S). A total of 11 beaches with rocky hard substrate belonging to 2 biogeographical provinces (Magellanic and Argentinean) were studied during April 2016. The trait composition of macrobenthic assemblages and functional diversity indices (Rao’s quadratic entropy) varied significantly along the Argentinean coast, suggesting that the latitudinal gradient influences the distribution of species with respect to combinations of trait modalities. Rao’s quadratic entropy, species richness, evenness, and Shannon-Wiener diversity showed a pattern with higher values in the sites located in high latitudes. The functional diversity patterns found coincide with the biogeographical provinces. The presence of intertidal sewage effluents considerably influence functional diversity and mask the effects of the latitudinal gradient on the macrobenthic communities on rocky shores.