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A total of 214 sampling sites of a hazardous waste disposal center were surveyed in a two-stage pollution investigation, including soil boreholes and groundwater monitoring wells. Results showed that chemical oxygen demand (COD) (4.00-2930.00 mg/L), fluoride (0.07-9.08 mg/L), chromium (0.12-1.20 μg/L), nickel (0.15-459.00 μg/L), lead (0.10-10.20 μg/L), cadmium (Cd) (0.05-16.40 μg/L), and beryllium (0.06-3.48 μg/L) were detected in groundwater samples. For soils, Cd in soil (78.7 mg/kg) exceeded the risk screening value (65 mg/kg) for soil contamination of the second type of development land (GB36600-2018), and there remained the risk of leakage in the landfill detection investigation. Then, a health risk assessment was carried out. Based on the definitions of the groundwater exposure pathway (HJ 25.3-2019) and the pollution investigation of groundwater, the carcinogenic and non-carcinogenic risks of groundwater were generally considered to be negligible. The carcinogenic risk and non-carcinogenic risk of the concerned pollutant in soil for risk assessment (Cd) under the condition of reutilization exceeded the corresponding acceptable levels (1E-06 and 1). The (non-)carcinogenic risk of Cd mainly came from oral intake of soil and inhalation of soil particles under two conditions of reutilization and non-utilization, so on-site workers and surrounding residents should be properly protected from the mouth and nose to minimize the intake of pollutants from the soil and soil particles. The area of soil contaminated by Cd was about 630.58 m 2 , and the amount of pollution was about 1261.16 m 3 . The heavy metal pollution was only distributed in the depth range of 0-2 m, and the suggested risk control value of soil pollutants under the condition of reutilization for Cd was 56 mg/kg. Based on different pollution characteristics of soil, groundwater, and the landfill, targeted control measures were proposed., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Zhu, Yang, He, Wang, Lu and Zhang.)

Surface water and groundwater have been experiencing increasing risks of contamination in recent years because of the poor management of the immense amounts of waste created by different human activities. Inappropriate dump sites have served for many years as marginal disposal sites for a wide range of wastes, including solid waste, fresh sewage and hazardous waste, in developing nations such as Ethiopia. Physical, anthropogenic and organic procedures continuously interact to deteriorate the waste. One of the results of these practices is artificially contaminated leachate, which is potentially hazardous waste from disposal sites. If not managed appropriately, such a dumping site can contaminate groundwater (through leachates) and surface water (through contaminant transport by flooding and groundwater movement). Along these lines, this study focuses on the applications of water quality index in the ground and surface water quality caused by the waste disposal site of Bahir Dar city within the Chilanchil Abay during the study period. Water testing was performed on five samples of surface water and six samples of groundwater in each month from 30th March (dry season) to 20th August (wet season). More than 13 water quality parameters, for example, pH, TDS, electrical conductivity, turbidity, temperature, dissolved oxygen (DO), TH, biochemical oxygen demand (BOD), chemical oxygen demand (COD), TC, NO3−, PO43−, Cr, Mn, and Pb contents, were examined in both ground and surface water. It was discovered that water quality status of the Chilanchil Abay watershed ranges from 15.87 to 36.6 for surface water and 42 to 46.2 for groundwater suggesting poor and marginal status for drinking water purpose. HIGHLIGHTS The study assesses and evaluates the groundwater quality of Chilanchil Abay watershed through the investigations of spatial and temporal variations of physico-chemical and bacteriological parameters.; This manuscript also evaluates the concentrations of the nutrients (phosphate and nitrate) in each borehole as compared to the standard values for drinking and irrigations.;

This paper presents the distribution of heavy metals in a groundwater system at a solid waste disposal site in Taiping, Perak. In this study several boreholes were constructed within the solid waste disposal site. Soil samples were collected from the alluvial deposits at 1 m intervals between 6 and 30 m depths from 6 boreholes using a down-hole hammer. The pore water content of the samples and the ground water was extracted in order to determine the concentrations of heavy metals, such as lead (Pb), manganese (Mn), chromium (Cr), iron (Fe), zinc (Zn) and cadmium, (Cd) using the Inductively Couple Plasma Spectrometer (ICP-MS). From the profiling results, the penetration of heavy metals into the groundwater system was obtained. A profile of heavy metal concentrations in the pore water of the core samples at several boreholes within the study area, and heavy metals concentration in groundwater under different conditions were obtained. Some of the heavy metals concentration such as Pb, Mn, Zn and Fe were high. These high concentrations exceed the maximum permissible concentration as specified in the Drinking Water Standard. Based on contour diagrams, the heavy metals can be detected down to 25 m depth towards the southeast of the landfill and appear to be localized. [ABSTRACT FROM AUTHOR]

A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence ( ρ < 20 Ωm), water table depth, and groundwater flow direction. A conductive anomaly ( ρ < 20 Ωm) outside wastes placement was interpreted as a contamination plume. Chargeability model was also able to imaging waste presence ( m > 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone ( m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/ ρ) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment. [ABSTRACT FROM AUTHOR]

The unconfined aquifer of Coronel Moldes is constituted mainly by aeolian fine sand/silt (loess) of Holocene age, where rural activities rely for the most part on the exploitation of groundwater. Environmental problems and concerns regarding this aquifer are related to mismanagement of urban solid and liquid waste, which has accumulated in an area of sand dunes since 1982. At this site, nearly 84 tons of different types of solid waste are dumped directly on the soil every week without any waste management or control. Also, liquid wastes originating from Coronel Moldes processed at an on-site-sanitation system have formed a lagoon inside the municipal waste disposal site. This paper is focused on the study of the hydrogeochemistry and geochemical modeling (with NETPATH) of a municipal disposal site of a typical phreatic aquifer of the Chacopampean plain. The groundwater directly below the municipal waste disposal site shows an increase in concentrations of Cl-, SO4-2, Na+, HCO3-, K+, Mg+2, NO3-, NO2-, Si, As, F-, Cu, Pb, COD, BOD5, as well as aerobic and anaerobic bacteria, and a decrease in dissolved oxygen. These values decrease 30 m downgradient from the waste disposal site but do not reach the background values found upstream of the disposal site. The geochemical modeling contributes to estimate the mixing proportions between the leachate and non-contaminated groundwater. The mixing models indicate that CE, Cl-, Na+ y SO4-2 in the aquifer immediately under and downstream of the municipal waste disposal site came principally from the lagoon leachates and possibly the disposal site, resulting in local geochemical conditions that favor certain reactions (exchange, precipitation, oxidation-reduction, and dissolution), which in turn control mobility and concentrations of Ca+2, As, F- and Si in the aquifer. It is probable that adsorption and precipitation processes of trace elements control the concentration of Fe and other metals in the contaminated aquifer. The principal attenuation processes (retardation, reduction, and chemical and biological transformation of contaminants) occur in the unsaturated zone, mostly in the soil, where biological activity is greater. The alkaline conditions and oxidants in the aquifer, along with redox reactions, ion exchange, precipitation/dissolution and adsorption, are the main processes that attenuate contamination through the unsaturated and saturated zone. [ABSTRACT FROM AUTHOR]

Direct current (DC) resistivity, self potential (SP) and very low frequency electromagnetic (VLF-EM) measurements are carried out to detect the spread of groundwater contamination and to locate possible pathways of leachate plumes, that resulted from an open waste disposal site of Çanakkale municipality. There is no proper management of the waste disposal site in which industrial and domestic wastes were improperly dumped. Furthermore, because of the dumpsite is being located at the catchment area borders of a small creek and is being topographically at a high elevation relative to the urban area, the groundwater is expected to be hazardously contaminated. Interpretations of DC resistivity geoelectrical data showed a low resistivity zone (<5 ohm-m), which appears to be a zone, that is fully saturated with leachate from an open dumpsite. The VLF-EM and SP method, support the results of geoelectrical method relating a contaminated zone in the survey area. There is a good correlation between the geophysical investigations and the results of previously collected geochemical and hydrochemical measurements. [ABSTRACT FROM AUTHOR]