STATISTICAL AND MULTIVARIATE TECHNIQUES TO TRACE THE SOURCES OF GROUND WATER CONTAMINANTS AND AFFECTING FACTORS OF GROUNDWATER POLLUTION IN AN OIL AND GAS PRODUCING WETLAND IN RIVERS STATE, NIGERIA.

Background: Groundwater is an important source of drinking water for the indigenous communities of Ebocha-Obrikom. Access to safe drinking water, in particular, is critical to one's health and, by extension, one's income and well-being. Underground wells are the primary supply of drinking water in the Niger Delta, and the groundwater is not always treated before consumption. As a result, water continues to be a vital environmental component that affects both humans and other life forms. Objectives: The aims of the research is to trace the sources and affecting factors of groundwater pollution via statistical and multivariate statistical techniques. Method: The investigation made use of standard analytical procedures. All sampling, conservation, transportation and analysis followed standard procedures described in APHA (2012). To prevent degradation of the organic substances, all obtained samples were transferred to the laboratory, while keeping in an icebox. Results: The study reveals that the greater the number of principal components extracted the greater variation in geochemical composition of the ground waters. It indicated that 34 parameters were distributed into six (6) and nine (9) principal components (PCs) extracted for groundwater samples for both rainy and dry seasons, potentially suggesting the input of different pollutants from different sources. Gas flaring, mineral dissolution/precipitation and anthropogenic input are the main sources of the physicochemical indices and trace elements in the groundwater. Groundwater chemistry is predominantly regulated by natural processes such as dissolution of carbonates, silicates, and evaporates and soil leaching, followed by human activities. Climatic factors and land use types are also important in affecting groundwater chemistry. Conclusion: Greater efforts should be made to safeguard groundwater, which is hampered by geogenic and anthropogenic activities, in order to achieve sustainable groundwater development. As a result, communities are recommended to maintain a groundwater management policy to ensure long-term sustainability. The study is useful for understanding groundwater trace sources in Rivers State's Ebocha-Obrikom districts. Such understanding would enable informed mitigation or eradication of the possible detrimental health consequences of this groundwater, whether through its use as drinking water or indirectly through consumption of groundwater-irrigated crops. As a result, determining its primary probable source of pollution (MPSP) is critical since it provides a clearer and more immediate interpretation. Furthermore, the research findings can be used as a reference for groundwater pollution prevention and water resource protection in the Niger Delta region of Nigeria.

Investigating the Potential Role of Geological Context on Groundwater Quality: A Case Study of the Grenville and St. Lawrence Platform Geological Provinces in Quebec, Canada

The hydrogeochemical study of the Lanaudière and Eastern Mauricie regions (Canada) demonstrates that trace elements appear to be better tracers of geological influence on groundwater chemistry than major elements. Isotopic ratios and the similar chemical composition of groundwater suggest that the physicochemical parameters of groundwater have a greater effect on hydrogeochemical mechanisms than the immediate geological environment The results allow us to propose a conceptual model of groundwater geochemical evolution with the aim to guide the protection and sustainable management of regional groundwater resources in the Lanaudière and Eastern Mauricie regions. These regions were selected because of their location at the boundary of the Grenville and St. Lawrence Platform geological provinces, representing two distinct geological contexts (Precambrian crystalline rocks and Paleozoic sedimentary rocks). Regional-scale hydrogeochemical and isotopic groundwater characterization was carried out to identify the role of the differences in regional geology on groundwater quality. Our analyses included major and trace elements, stable isotopes, and multivariate statistics. Similar processes are at the origin of dissolved major chemical elements and suggest that soluble minerals common to both geological provinces control groundwater chemistry. If differences exist, they are due to the hydrogeological conditions of the samples, such as residence time or groundwater entrapment at the time of the postglacial marine incursion of the Champlain Sea, rather than the geological context. Some differences, sometimes significant, were observed for some minor elements (F−, Mn2+, H2S), which implies a more comprehensive knowledge of the chemistry of the stratigraphic units within the Lanaudière and Eastern Mauricie aquifers.

Hydrochemical peculiarities and groundwater quality assessment of the Birimian and Tarkwaian aquifer systems in Bosome Freho District and Bekwai Municipality of the Ashanti Region, Ghana

The Birimian and Tarkwaian aquifer systems are the main sources of water supply for the Bosome Freho District and Bekwai Municipality inhabitants in the Ashanti region of Ghana. A hydrogeochemical assessment was carried out to ascertain the natural baseline chemistry of the groundwaters and the factors influencing groundwater chemistry in these two areas. A multivariate statistical tool consisting of principal component analysis (PCA) and hierarchical cluster analysis (HCA) together with hydrochemical graphical plots was applied on 64 groundwater samples. The Q–mode HCA results were used to explain the changes in groundwater chemistry along the flow paths where three spatial groundwater zones and water types were delineated. The first type consists of Ca–Mg–HCO3 freshwater (recharge zone), which transitions into Ca–Na–HCO3 or Na–Ca–HCO3 mixed waters (intermediate zone) and finally evolves to the third type of Na–Ca–Mg–HCO3–Cl water (discharge zone). The study also reveals that the natural process influencing water chemistry is groundwater–rock interaction from carbonate and silicate weathering/dissolution, aided by carbonic acid from precipitation and releases concentration of Na+, Ca2+, Mg2+, and HCO3− into the groundwaters significantly. The chloro-alkaline indices also reveal cation exchange as the principal natural factor that controls groundwater chemistry in the area. Inverse geochemical modelling shows the dissolution of primary minerals such as dolomite, plagioclase, halite, gypsum, and precipitation of calcite and chlorite along the groundwater flow path. Anthropogenic activities have little influence on groundwater chemistry. The quality of groundwater in the Bosome Freho District and Bekwai Municipality is suitable for irrigational use and drinking water consumption. The results obtained so far will contribute to research paucity in the study area and serve as a guide for decision-makers for improved water resources management.

Hydrogeochemical Characterization and Its Seasonal Changes of Groundwater Based on Self-Organizing Maps

Water resources are scarce in arid or semiarid areas; groundwater is an important water source to maintain residents’ lives and the social economy; and identifying the hydrogeochemical characteristics of groundwater and its seasonal changes is a prerequisite for sustainable use and protection of groundwater. This study takes the Hongjiannao Basin as an example, and the Piper diagram, the Gibbs diagram, the Gaillardet diagram, the Chlor-alkali index, the saturation index, and the ion ratio were used to analyze the hydrogeochemical characteristics of groundwater. Meanwhile, based on self-organizing maps (SOM), quantification error (QE), topological error (TE), and the K-means algorithm, groundwater chemical data analysis was carried out to explore its seasonal variability. The results show that (1) the formation of groundwater chemistry in the study area was controlled by water–rock interactions and cation exchange, and the hydrochemical facies were HCO3-Ca type, HCO3-Na type, and Cl-Na type. (2) Groundwater chemical composition was mainly controlled by silicate weathering and carbonate dissolution, and the dissolution of halite, gypsum, and fluorite dominated the contribution of ions, while most dolomite and calcite were in a precipitated state or were reactive minerals. (3) All groundwater samples in wet and dry seasons were divided into five clusters, and the hydrochemical facies of clusters 1, 2, and 3 were HCO3-Ca type; cluster 4 was HCO3-Na type; and cluster 5 was Cl-Na type. (4) Thirty samples changed in the same clusters, and the groundwater chemistry characteristics of nine samples showed obvious seasonal variability, while the seasonal changes of groundwater hydrogeochemical characteristics were not significant.

Groundwater Chemistry at Deep Aquifer in Koyra: Khulna, Bangladesh

Koyra (Khulna District) is the coastal Upazila of Bangladesh and is very susceptible to salinity intrusion. The surface and shallow tube well water in the Upazila is naturally saline. The quality of subterranean tube well water in the deliberate area is hardly presented for different Unions of Koyra. Dakshin Bedkashi Union of Koyra is very saline prone. Therefore, the groundwater chemistry of Dakshin Bedkashi Union was determined to legalize if the groundwater is fit for drinking and irrigation or not. Spatially dispersed 30 water samples were collected from the deep aquifer (550 to 700 feet depth) in December, 2016 and analyzed for physico-chemical properties. The outcomes were compared with WHO, USEPA and BBS drinking water quality standard and with FAO standard for irrigation purpose. The pH varied from 6.73 to 8.33, indicating that the water samples were within the WHO drinking water quality standard. The TDS showed a long range variation (230.5 to 2052.0 ppm) with an average of 841.23 ppm, of which 33% of water sources exceeded BBS standard value. The mean value of salinity was 0.65 (±0.43) ppt and EC was 1,400.9 (±904.18) µS cm-1. The loads of key ions were ranked as Na+> Ca2+> Mg2+> K+ and HCO3-> Cl-> SO42-> NO3-> PO4-. The Piper diagram demonstrated that the existing hydro-chemical facies of groundwater were Na+-Cl--HCO3- and Na+-Ca2+-HCO3- type. The Gibbs diagram illustrated that the chemical arrangement of groundwater is mainly misrepresented by rock weathering. Silicate weathering was the profuse process along study area. The Wilcox diagram proved that the greater water sources were allowable to suspicious for irrigation. The core component analysis ensured that rock suspension and sea water intrusion was the primary source of ions in groundwater. The controlling factors of groundwater chemistry were typically related to geologic factors, while the anthropogenic factors have not any momentous effects.