Controlling factors and health risks of groundwater chemistry in a typical alpine watershed based on machine learning methods

Anthropogenic impacts and quantitative sources of nitrate in a rural-urban canal using a combined PMF, δ15N/δ18O-NO3-, and MixSIAR approach

Nitrate (NO3-) pollution in irrigation canals is of great concern because it threatens canal water use; however, little is known about it at present. Herein, a combination of positive matrix factorization (PMF), isotope tracers, and Mixing Stable Isotope Analysis in R (MixSIAR) was developed to identify anthropogenic impacts and quantitative sources of NO3- in a rural-urban canal in China. The NO3- concentration (0.99-1.93 mg/L) of canal water increased along the flow direction and was higher than the internationally recognized eutrophication risk value in autumn and spring. The inputs of the Fuhe River, NH4+ fertilizer, soil nitrogen, manure & sewage, and rainfall were the main driving factors of canal water NO3- based on principal component analysis and PMF, which was supported by evidence from δ15N/δ18O-NO3-. According to the chemical and isotopic analyses, nitrogen transformation was weak, highlighting the potential of δ15N/δ18O-NO3- to trace NO3- sources in canal water. The MixSIAR and PMF results with a <15% divergence emphasized the predominance of the Fuhe River (contributing >50%) and anthropogenic impacts (NH4+ fertilizer plus manure & sewage, >37%) on NO3- in the entire canal, reflecting the effectiveness of the model analysis. According to the MixSIAR model, (1) higher NO3- concentration in canal water was caused by the general enhancement of human activities in spring and (2) NO3- source contributions were associated with land-use patterns. The high contributions of NH4+ fertilizer and manure & sewage showed inverse spatial variations, suggesting the necessity of reducing excessive fertilizer use in the agricultural area and controlling blind wastewater release in the urban area. These findings provide valuable insights into NO3- dynamics and fate for sustainable management of canal water resources. Nevertheless, long-term chemical and isotopic monitoring with alternative modeling should be strengthened for the accurate evaluation of canal NO3- pollution in future studies.

Groundwater for drinking and industrial purposes: A study of water stability and human health risk assessment from black sand mineral rich coastal region of Kerala, India

Tempero-spatial analysis of groundwater to disseminate the level of drinking water quality and industrial suitability to meet the developmental requirement of a region is a significant area of research. Accordingly, groundwater quality and geochemical interactions prevailed in a black sand mineral rich coastal village is systematically presented in appraisal of drinking and industrial uses for economic engineering purposes. The study area focused is Alappad village, Kollam, Kerala, India has numerous ecological features in a sustainable perspective. The region is unique with placer deposits where an alluvial soil aquifer-saline water-freshwater interaction occurs. This dynamics decides the pertinent hydro geochemistry, potable and designated uses of ground water in season wise. Coastal area is hereby presented based on water quality parameters predicted with the health risk assessment model with a view on human health and cancer risk due to ions (Pb, Ni, Cu, Ba, Fe, Al, Mn, Zn) in groundwater.. To ascertain industrial usage, ground water is evaluated by Langelier saturation index (LSI), Ryznar stability index (RSI), Aggressive index (AI), Larson-Skold index (LS) and Puckorius scaling index (PSI) and inferences are complemented. Chemical weathering and evaporation processes are the natural factors controlling hydrochemistry of this aquifer. This complex coastal system has Nemerow pollution index (NPI) of moderate pollution for total dissolved ions of Fe and lesser for Cu, and Cr present in groundwater. LSI indicates, water is scale forming but non corrosive (46% in PRM, 20% in MON and 47% in POM). Water quality index (WQI) in POM (ranged 28.7-79.9) was excellent for drinking, followed by PRM (23.6-218.2) and MON (33.4-202.7) seasons. This groundwater bears temporary hardness with the dominance of Ca-Mg-HCO3 water type. Health risk assessment of non-carcinogenic risk index of trace metals (Fe, Zn, Mn, and Pb) revealed, children are at 'low risk' and 'medium' risk with Ni and Cu. The carcinogenic risk index indicated 93% of samples were high Ni induced cancer risk for children, and 87% for adults due to long term ingestion (drinking water intake) pathway. Studies specific on placer mineral deposited coastal region of India are not sufficiently reported with a focus on the above perspectives. Growing need of rare earths for material, device and energy applications, placer mineral explorations can destabilise the coastal hydrosphere. Interrelations of mineral soil - water chemistry prevailed and health hazard predicted would kindle a set of sustainable deliberations. This study summarises the drinking and industrial use of coastal groundwater for future development and human well-being on the basis of quality criteria, corrosion proneness, water stability and health risk factors.

Hydrogeochemical and isotopic evolution of groundwater in shallow and deep aquifers of the Kabul Plain, Afghanistan

Groundwater from shallow and deep aquifers are widely used for drinking, agricultural and industrial use in Kabul, the capital of Afghanistan. However, unplanned urbanization and rapid population growth has led to the installation of numerous unlicensed wells to meet the public demand. This has caused to extraction of huge amounts of groundwater from the subsurface and further deterioration of groundwater quality. Therefore, understanding the hydrogeochemical characteristics of groundwater in shallow aquifers and deep aquifers is imperative for sustainable management of the groundwater resource in Kabul Plain. Thus, in this study, we used a multi-parameter approach, involving hydrochemical and environmental isotopes to understand the geochemical evolution of entire groundwater system of the Kabul Plain including river and dam water. The results of this study show that shallow and deep aquifers are dominantly of Mg-(Ca)-HCO3 and Na-Cl water type, respectively. We observed that (1) water-rock interaction is the major contributing factor to the chemical compositions of groundwater in the Kabul Plain; (2) groundwater in deep aquifer is mainly influenced by silicate weathering, and dissolution of evaporitic and carbonate minerals and reverse cation exchange; (3) dissolution of carbonates and silicate weathering plays a pivotal role in the groundwater chemistry of shallow aquifer; (4) the stable isotopes of groundwater display that the shallow aquifer is principally recharged by river water and local precipitation; (5) the tritium analysis exhibited that groundwater of shallow aquifer was primarily recharged recently, whereas groundwater of deep aquifer is the mixture of pre 1953 with post 1953 groundwater. This study revealed that there are hydraulic interactions between the two aquifers and the deep aquifer is recharged through shallow aquifer. The findings of this study would be useful for Afghanistan's water authorities to develop an effective strategy for sustainable water resources management in the Kabul Basin.