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Pesticides are commonly applied in agriculture to protect crops from pests, weeds, and harmful pathogens. However, chronic, low-level exposure to pesticides can be toxic to humans. Photochemical degradation of pesticides in water, soil, and other environmental media can alter their environmental fate and toxicity. Compound-specific isotope analysis (CSIA) is an advanced diagnostic tool to quantify the degradation of organic pollutants and provide insight into reaction mechanisms without the need to identify transformation products. CSIA allows for the direct quantification of organic degradation, including pesticides. This review summarizes the recent developments observed in photodegradation studies on different categories of pesticides using CSIA technology. Only seven pesticides have been studied using photodegradation, and these studies have mostly occurred in the last five years. Knowledge gaps in the current literature, as well as potential approaches for CSIA technology for pesticide monitoring, are discussed in this review. Furthermore, the CSIA analytical method is challenged by chemical element types, the accuracy of instrument analysis, reaction conditions, and the stability of degradation products. Finally, future research applications and the operability of this method are also discussed.

The Mano River is a transboundary river that runs through Cote d’Ivoire, Liberia, Guinea, and Sierra Leone. According to a 2018 United Nation report on Sustainable Development Goal (SDG) 6.5, which aims to improve the adoption of cohesive water resource management by 2030; the impact of this goal on the Mano River management is minimal. The research summarizes previous studies using an integrative literature review method, drawing general conclusions and identifying unsolved problems with respect to water resources management. The research finding demonstrated that existing water stress and poor management as exacerbated by socioeconomic practices in the region are the major threats to achieve SDG 6.5. As a result of these activities, long-term management of the river basins has become extremely difficult. The research informs a discussion to achieve cooperative water resource management, which is best achieved by shared collaboration and shared interests as described by SDG 6.5.

Cu-Zn-Fe Layered double hydroxides (LDH) and LDH dispersed on bamboo biochar (LDHBC) was used to study the adsorption of Atrazine by characterizing the adsorption kinetics, isotherms and response surface methodology (RSM) to reveal interactive effects of pH, adsorbent dosage and adsorbate initial concentration towards LDH optimum performance. The estimate of parameters determined for Langmuir isotherm quantities were in the range (21.84-37.91 mg/g) for LDH and (63.64-87.04 mg/g) for LDHBC. Regeneration and reusability after five cycles detected that the adsorption efficiencies of the adsorbents were reduced to 36% for LDH and 66% for LDHBC. Box Behnken design analysis could further reveal optimized conditions for higher Atrazine removal by LDH up to 74.8%. The adsorption mechanisms could be determined by π-π interactions occurring at the interfaces by hydrogen bonding and pore filling effects.

Acid Rock Drainage (ARD) is a well-known problem related to the mining industry due to its hazardous environmental effects. Metal-rich drainage and acid effluent transmitted from mine waste dumps compromise environmental quality of groundwater and surface water systems destroying aquatic life and increasing human health risks. This study was aimed at assessing the acid and metal drainage potential from the Subriso East Rock Dump (SERD) located in the Wassa East district of Ghana on ground and surface water quality in the catchment using a system of monitoring boreholes, reference boreholes and river samples. Water samples were collected from deep and shallow monitoring boreholes and surface water within the immediate environs of the SERD from August 2012 to February 2013 for laboratory and statistical analysis. Parameters analyzed include sulphate, alkalinity, Arsenic (As), Manganese (Mn), Iron (Fe), Zinc (Zn), Copper (Cu), Cadmium (Cd), Mercury (Hg), Aluminum (Al), Silver (Ag) and lead (Pb) and their concentrations compared with Ghana Standards Authority (GSA) GSB (2009) and WHO (2017) standards. Results indicate that surface and groundwater were not impacted by the SERD possibly because there was no generation of acid or metal-loaded effluent from the SERD into the environment. Physicochemical variables between monitoring boreholes did not differ significantly from conditions in the reference boreholes. Similarly, comparison of upstream and downstream river conditions did not yield any statistical significance (p > 0.05). Mn and Fe concentrations were above the WHO (2017)/GSB (2009) standards. Heavy metal concentrations in surface and groundwater were below detection limits except manganese and iron whose concentrations exceeded the recommended guidelines. No significant environmental impacts exist that could be attributed to the waste rock dump and may be as a result of engineering designs and mechanisms which prevent acid generated water from reaching the external environment. Furthermore, the geology of the study area potentially could be slightly inert having the potential to generate ARD under appropriate conditions. Again, the young age of the waste rock dump is a factor that may contribute to ARD generation under appropriate condition. Routine monitoring of groundwater and surface water sources is required to determine future acid generation of the SERD and its environmental impacts. The results of this study will assist decision makers and environmental managers to plan effectively to mitigate future impacts as mining waste rock dumps are known to increase in acid generation potential with age.

Heavy metal pollution from both anthropogenic and natural processes can have significant effect on environmental quality of stream and river systems. However, in Ghana, heavy metal pollution of waterbodies is attributed mainly to mining activities but the role of natural mechanisms in altering stream water and sediment quality in relation to heavy metals has received little attention. Spatial and temporal variation in water quality parameters and heavy metal concentrations in water and sediments were studied comparatively in a river and two streams in a gold-rich watershed impacted by heavy mining activities. Samples were collected monthly over a twelve-month period from November 2010 to October 2011 from upstream (unmined) and downstream (mined) sections of the studied streams. Parameters measured include temperature, dissolved oxygen, conductivity, pH, turbidity, colour, mercury (Hg) and arsenic. High spatial variability of water quality parameters was found. Hg concentrations in water were extremely low in both upstream and downstream areas. Maximum geochemical background levels of Hg in unmined pristine areas were 2.45 mg/g whilst arsenic was 29.10 mg/g. By contrast, gold-mined downstream areas recorded Hg and arsenic concentrations of 8.75 mg/g and 82.53 mg/g in stream sediments respectively. Levels of Hg and arsenic in sediments were several orders of magnitude greater than concentrations in surface water in downstream sections and this may be explained by substances originating from mining activities, upstream transport or remobilized sedimented materials in the overlying water column. Our study showed that both natural and human activities may contribute to heavy metal pollution in the highly mineralized watershed of the Pra River Basin. Human factors are however likely to amplify the natural background levels of heavy metals.

Over the years, erratic rainfall pattern coupled with increasing population has led to the reliance on groundwater as an alternative and sustainable source for crop irrigation to meet increasing food demand. Irrigation of crops though essential, if not done with care through good practices and use of quality water can lead to soil salinization and ecological unsustainability. This study was carried out to assess the salinity of groundwater used for irrigation in three sub catchments in the Upper Athi River Basin of Kenya. Stratified random sampling technique was used to select representative boreholes and shallow wells for the study. In all, water from 17 boreholes and 17 shallow wells spread across the study area were sampled and analysed for selected physico-chemical properties. Standard methods were used for all the laboratory analysis; temperature, pH and electrical conductivity (EC) of water samples were measured in the field. The results obtained were compared with FAO Water Quality Guidelines for Irrigation. pH ranged from 4.2 to 7.13 indicating weak acidity with about 75% samples falling below lower guideline value. EC values ranged from 467 to 1328 μS/cm which were within FAO and NEMA permissible limits for irrigation purposes. All salts ions were within permissible irrigation water suitability standards except CO3-, Cl and K+. 97% samples had above the recommended carbonate concentrations while 80% had more potassium than the recommended value with the remaining 20% being boreholes. In relation to chloride concentrations, samples from shallow wells are not suitable for sprinkler irrigation since they were above the recommended levels; however, 58% were suitable for surface irrigation. For the boreholes, chloride concentrations were suitable for both surface and sprinkler irrigation. In conclusion, the boreholes had less ions as compared to shallow wells. This research may serve as a preliminary study to provide baseline information that may direct future water quality assessment studies in the study area. Key words: Irrigation, groundwater quality, boreholes, shallow wells, physico-chemical quality, salinity, sodicity.