Groundwater Media Research Articles

Multivariate and Statistical Assessment of Solid Wastes Contamination from Waste Dump Sites on Soil and Perched Aquifers in a Rapidly Developing City

The effect of waste dumps on groundwater quality on perched aquifers in Nsukka and environs was investigated by applying multivariate statistical analyses using Statgraphics Centurion XVII, ArcGIS 10.2.2 and Surfer 10 software on hydrochemical parameters from soil (0 cm and 15 cm depth) and groundwater media. Factor analysis, correlation, principal component analysis and cluster analysis reflect biodegradable domestic solid contaminants, automobile contaminants and construction or building contaminants. The significant or positive correlation between parameters was taken at value equal to or greater than 0.5. Chromium showed positive or significant correlation with copper (0.98), cadmium (0.91), nitrate (0.87) and potassium (0.82) indicating that they are from the same source. Zinc showed positive correlation with manganese (0.89) and pH (0.70) showing similar source. The first cluster showed chromium, copper, cadmium, nitrate, potassium and iron which could be attributed to market and domestic biodegradable wastes. The second cluster showed parameter association for lead, EC and mercury which could be attributed to automobile wastes. The third cluster showed zinc, manganese and pH which could be attributed to construction and building wastes. This showed that the third cluster is the major contributor to the soil pH. Based on the Normality Tests (Shapiro-Wilk significance test) to determine P-Value of the analyzed parameters, in the study area; there was no significant spatial variation (@p > 0.05) in the values of parameters such as chromium, iron, pH in the impact zone and the control area. Conversely, the other parameters were statistically significant. For the groundwater analysis, the dendrogram extracted three clusters highlighting the parameter associations according to their possible sources of occurrence. The first cluster showed potassium, sodium, DOI, manganese, and bicarbonate, which could be attributed to construction and building wastes. The second cluster showed parameter association for sulfate, nitrate, calcium and chloride; which could be domestic biodegradable solid waste. The third cluster showed pH, EC, TDS, Cu+, Pb2+, Hg+, Fe2+, Cr2+ and Cd2+ which could be attributed to automobile wastes.

Magnitude and Direction of Groundwater Seepage Velocity in Different Soil and Rock Materials

To understand and anticipate flow in various groundwater media, the magnitude and direction of groundwater flow velocity must be deemed. The studied area which is called Halabja-Sadiq Basin is in the northeastern part of Iraq and covers an area of approximately 128,000 square hectometers. There are several groundwater aquifers in this region that supply nearly over 90% of all water needs. Subsequently, it is of highly requirement to identify various groundwater behaviors in the area. The objective of this study is to estimate the magnitude and direction of the groundwater seepage velocity with the aid of groundwater tool in Geographic Information System technology. Refer to the results of this analysis, the magnitude value of groundwater flow velocity ranged from 0 to 51 m/d, whilst the general flow movement is from the eastern part to the western part of the study area. The factor governing the direction of flow and velocity magnitude indicates the direction of dipping of the geological formation strata, the high head of groundwater in the eastern part, and the low transmissivity properties of aquifer materials in the western part.

Microbiologically influenced corrosion of ferritic steel–zirconium-based metal waste form alloy under simulated geological repository environment

ABSTRACTThe present work focused on investigating the microbiologically influenced corrosion (MIC) susceptibility of ferritic steel–Zr-based metal waste form (MWF) alloy in simulated ground water media, cultured with a common biofilm former Bacillus sp. Total viable count studies showed a good bacterial attachment on the surface of MWF alloy. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) examination of the biofilm MWF surface revealed preferential adhesion of microbes on Fe–Zr-rich intermetallic phases. Anodic polarisation and electrochemical impedance spectroscopic (EIS) studies showed active corrosion potential (Ecorr), higher passive current density (Ipass) and decreased polarisation resistance (Rp) values, confirming the corrosion susceptibility of MWF alloy under Bacillus sp. biofilm.

Groundwater residence time in a dissected and weathered sandstone plateau: Kulnura–Mangrove Mountain aquifer, NSW, Australia

Groundwater residence time in the Kulnura–Mangrove Mountain aquifer was assessed during a multi-year sampling programme using general hydrogeochemistry and isotopic tracers (H2O stable isotopes, δ13CDIC, 3H, 14C and 87Sr/86Sr). The study included whole-rock analysis from samples recovered during well construction at four sites to better characterise water–rock interactions. Based on hydrogeochemistry, isotopic tracers and mineral phase distribution from whole-rock XRD analysis, two main groundwater zones were differentiated (shallow and deep). The shallow zone contains oxidising Na–Cl-type waters, low pH, low SC and containing 3H and 14C activities consistent with modern groundwater and bomb pulse signatures (up to 116.9 pMC). In this shallow zone, the original Hawkesbury Sandstone has been deeply weathered, enhancing its storage capacity down to ∼50 m below ground surface in most areas and ∼90 m in the Peats Ridge area. The deeper groundwater zone was also relatively oxidised with a tendency towards Ca–HCO3-type waters, although with higher pH and SC, and no 3H and low 14C activities consistent with corrected residence times ranging from 11.8 to 0.9 ka BP. The original sandstone was found to be less weathered with depth, favouring the dissolution of dispersed carbonates and the transition from a semi-porous groundwater media flow in the shallow zone to fracture flow at depth, with both chemical and physical processes impacting on groundwater mean residence times.Detailed temporal and spatial sampling of groundwater revealed important inter-annual variations driven by groundwater extraction showing a progressive influx of modern groundwater found at >100 m in the Peats Ridge area. The progressive modernisation has exposed deeper parts of the aquifer to increased NO3− concentrations and evaporated irrigation waters. The change in chemistry of the groundwater, particularly the lowering of groundwater pH, has accelerated the dissolution of mineral phases that would generally be inactive within this sandstone aquifer triggering the mobilisation of elements such as aluminium in the aqueous phase.

Corrosion and Corrosion Inhibition of Mild Steel in Groundwater at Different Temperatures by Newly Synthesized Benzotriazole and Phosphono Derivatives

The corrosion and corrosion inhibition of mild steel in groundwater using 1-(2-pyrrolecarbonyl)-benzotriazole (PBTA) and 1-(2-thienylcarbonyl)-benzotriazole (TBTA) with 2-phosphonoacetic acid (PAA), 4-phosphonobutyric acid (PBA), and Zn2+ at various temperatures ranging from 30 to 60 °C were reported. The study was performed using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) along with X-ray diffraction (XRD) and Scanning electron microscopy (SEM) investigations. PDP measurements proved that the presence of inhibitors decreases the corrosion of still by decreasing its corrosion current density. EIS data showed that the charge transfer resistance of steel increases in the groundwater containing inhibitors. XRD and SEM investigations confirmed that the inhibition of mild steel is achieved by the adsorption of the inhibitor molecules on the steel surface. All results indicated that the presence of PBTA and TBTA along with Zn2+ as well as PBA offered good inhibition efficiency against corrosion of mild steel in the groundwater media.

Integrating Address Geocoding, Land Use Regression, and Spatiotemporal Geostatistical Estimation for Groundwater Tetrachloroethylene

Geographic information systems (GIS) based techniques are cost-effective and efficient methods used by state agencies and epidemiology researchers for estimating concentration and exposure. However, budget limitations have made statewide assessments of contamination difficult, especially in groundwater media. Many studies have implemented address geocoding, land use regression, and geostatistics independently, but this is the first to examine the benefits of integrating these GIS techniques to address the need of statewide exposure assessments. A novel framework for concentration exposure is introduced that integrates address geocoding, land use regression (LUR), below detect data modeling, and Bayesian Maximum Entropy (BME). A LUR model was developed for tetrachloroethylene that accounts for point sources and flow direction. We then integrate the LUR model into the BME method as a mean trend while also modeling below detects data as a truncated Gaussian probability distribution function. We increase available PCE data 4.7 times from previously available databases through multistage geocoding. The LUR model shows significant influence of dry cleaners at short ranges. The integration of the LUR model as mean trend in BME results in a 7.5% decrease in cross validation mean square error compared to BME with a constant mean trend.

Corrosion issues related to disposal of 316 SS–zirconium metal waste form under simulated repository conditions

Metal waste form (MWF) alloy of D9 stainless steel with 8·5 wt-% zirconium was cast and evaluated for the corrosion behaviour. The microstructure, phase analysis, corrosion resistance and passive film properties of the alloy were evaluated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and electrochemical methods. The corrosion performance of MWF alloy was carried out in demineralised (DM) water at pH 1, 5 and 8 and also in simulated Kalpakkam and Rajasthan ground water systems. In X-ray diffraction analysis, the identified phases are mostly iron based solid solutions of γ-austenite, Zr–Fe type and Ni–Zr type intermetallics. The typical microstructure of MWF alloy showed the presence of solid solution and the intermetallics. The anodic polarisation results of MWF alloy in Rajasthan ground water and in DM water at pH 5 and 8 showed higher breakdown potential compared with DM water at pH 1 and in Kalpakkam ground water. The electrochemical impedance spectroscopic results of MWF alloy in different media showed the influence of ground water media. The surface morphology after passivation and polarisation revealed the possibility of different types of deposition and dissolution. The corrosion behaviour of MWF alloy in different simulated media and its relation to microstructure and surface morphology are discussed based on the results obtained in relevance with geological repository conditions.

Surface and electrochemical characterization of pitting corrosion behaviour of 304 stainless steel in ground water media

The effectiveness of aminotrimethylidene phosphonic acid (ATMP) as a corrosion inhibitor in association with a bivalent cation like Zn2+ and non-ionic surfactant like polyoxyethylene sorbitan monooleate (Tween 80) were investigated by measuring corrosion losses using electrochemical techniques. The corrosion of 304 stainless steel in the ground water medium was inhibited by complexation of the inhibitor. A combined inhibition effect was achieved by adding both ATMP and Zn2+ along with Tween 80. The formulation functioned as a mixed type inhibitor. The synergistic effect of the inhibitor compound is calculated. Luminescence spectra, FTIR spectra, XRD, XPS and scanning electron microscopic studies were carried out to understand the mode of corrosion inhibition and also the morphological changes on the metal surface.

Removal of137Cs from an intermediate level liquid waste by using various ion-exchange media

An intermediate level liquid waste (ILLW or Category III waste) stream was treated for the removal of radioactive Cs in pilot scale experiments, using three different ion exchange media. Results indicated that the polyacrylic fibre coated with cupric ferric hexacyanoferrate (CuFeHCF-fibre composite) was the most efficient, followed by cupric hexacyanoferrate loaded ion exchange resin (CuHCF-resin) and mixed zeolites (AR-1, 4A and 13X in the ratio 6:1:1). The mixed zeolites column and the CuFeHCF-fibre column were used in series in order to get a high total decontamination factor (DF). Leaching studies on the CuFeHCF-fibre composite loaded with137Cs, in demineralised (DM) water, tap water and ground water media indicated a release of about 19.3%, 25.5% and 41.3% of137Cs, respectively, in a period of about 8 months. XPS studies with CuFeHCF-fibre composite indicated some chemical interaction between the CuFeHCF precipitate and the polyacrylic fibre. Some of the possible disposal options for the CuFeHCF-fibre composite have also been discussed.