Evaluation of surface water and groundwater contamination in a MSW landfill area using hydrochemical analysis and electrical resistivity tomography: a case study in Sichuan province, Southwest China

Comparing roles of multiple contamination indicators in tracing groundwater pollution nearby a typical municipal solid waste (MSW) landfill

Groundwater pollution resulting from leachate leakage at landfill sites has garnered significant attention. Investigating the migration of pollutants from these landfills to adjacent groundwater is crucial for understanding the diffusion patterns and extent of contamination. It is imperative to develop cost-effective yet highly efficient tracer techniques to aid landfill operators in monitoring groundwater contamination stemming from their operations. The primary objective of this research was to compare the roles of conservative tracers sodium (Na+) and chloride (Cl-), and conventional pollutants permanganate oxidation (CODMn), ammonium nitrogen (NH4 +-N), lead (Pb), and zinc (Zn) in assessing pollution levels from municipal solid waste landfills to groundwater. For this purpose, a typical municipal solid landfill was selected to investigate the origin of Cl-, groundwater quality, and spatiotemporal variations of multiple contaminations. Geochemistry analyses revealed that Na-Cl and Ca-HCO3 were the dominant groundwater type in this study and landfill was the primary source of Cl- in groundwater, with an average contribution of 78 %. Groundwater in proximity to the landfill (5#, 2#, 22#, 23#) exhibited elevated concentrations of Na+ (15.6-914.0 mg/L), Cl- (8.9-1352.0 mg/L), CODMn (0.54-95.9 mg/L), and NH4 +-N (0.33-49.0 mg/L), yet demonstrated reduced levels of Pb (0.2-391.0 μg/L) and Zn (2.0-112.8 μg/L). In contrast, groundwater located at a considerable distance from the landfill (13#, 18#, 15#, 26#) displayed the inverse trend, with relatively low concentration of Na+ (3.2-8.5 mg/L), Cl- (0.1-0.7 mg/L), CODMn (0.28-4.78 mg/L), and NH4 +-N (0.03-0.52 mg/L), but increased levels of Pb (1.2-483.0 μg/L) and Zn (1.6-357.0 μg/L). The primary determinant of groundwater quality near the landfill was NH4 +-N, with the highest pollution index (Pi) of 492.85, whereas Pb was the predominant factor affecting water quality in areas distant from the landfill, with the highest pollution index (Pi) of 10.9. While no discernible seasonal variation was detected for all pollutants, spatial variation can be observed that pollution levels decreased progressively with increasing distance from the landfill, a trend particularly corroborated by the conservative Cl- and Na+ measurements. This research suggests that conservative ions, such as Cl- and Na+, exhibit superior efficacy in tracing the pollution range from municipal solid landfills to groundwater. Therefore, monitoring these conservative ions in groundwater can yield a more precise understanding of the extent of groundwater contamination originated from landfills.

Arthropods in landfills and their accumulation potential for toxic elements: A review

Landfills, as a source of potentially toxic elements (PTEs), pose a threat to the environment and human health. A literature review was conducted to explore the diversity of arthropods inhabiting solid waste landfills, as well as on the bioaccumulation of PTEs by arthropods. This review presents scientific papers over the last 20 years. Their importance in landfill ecosystems has been the subject of research; however, the issue of the accumulation of compounds such as toxic elements is emphasized only in a few studies. The bioaccumulation of PTEs was studied for 10 arthropod species that founded in landfills: Orthomorpha coarctata and Trigoniulus corallinus (class Diplopoda), Armadillidium vulgare and Trachelipus rathkii (class Malacostraca), the 6 species of the class Insecta - Zonocerus variegatus, Anacanthotermes ochraceus, Macrotermes bellicosus, Austroaeschna inermis, Calathus fuscipes and Harpalus rubripes.

Landfill leachate a potential challenge towards sustainable environmental management

The increasing amount of waste globally has led to a rise in the use of landfills, causing more pollutants to be released through landfill leachate. This leachate is a harmful mix formed from various types of waste at a specific site, and careful disposal is crucial to prevent harm to the environment. Understanding the physical and chemical properties, age differences, and types of landfills is essential to grasp how landfill leachate behaves in the environment. The use of Sustainable Development Goals (SDGs) in managing leachate is noticeable, as applying these goals directly is crucial in reducing the negative effects of landfill leachate. This detailed review explores the origin of landfill leachate, its characteristics, global classification by age, composition analysis, consequences of mismanagement, and the important role of SDGs in achieving sustainable landfill leachate management. The aim is to provide a perspective on the various aspects of landfill leachate, covering its origin, key features, global distribution, environmental impacts from poor management, and importance of SDGs which can guide for sustainable mitigation within a concise framework.

Human Health Risk Assessment Is Associated with the Consumption of Metal-Contaminated Groundwater around the Marituba Landfill, Amazonia, Brazil

Groundwater is present in its purest form beneath the earth's surface. However, metal contamination is potentially a problem faced by many countries. For this reason, the present study aims to make an assessment of the risks associated with groundwater consumption around the Marituba landfill in an Amazon region. The present study was characterized as transversal with the use of primary data. The sampling occurred in a stratified random way, performed in two radii of action being the 1st radius of 2.5 km away from the landfill and the 2nd radius of 3.5 km away from the landfill to the neighborhoods. A total of 184 points were collected. In all communities the average daily dose (ADD) was higher than the reference oral dose (Rfd), for the metals As, Pb and Mn the risk quotient (HQ) was greater than 1 (one) in all neighborhoods, the concentration of Mn in the least exposed neighborhood was greater than 10 µg.L^-1, even at a distance of 3.5 km from the landfill. The average concentrations for As and Pb did not exceed the recommended, however, they were more significant for the Beira Rio neighborhood, respectively 1.47 µg.L^-1 and 1.9 µg.L^-1. And the average concentration for Cu was more significant for the Uriboca neighborhood 18.20 µg.L^-1, but within the recommended. The average of the general concentration of Heavy Metals Pollution Index (HPI) of the water consumed was 80.03, indicating that the water consumed by the population is contaminated by metals.

A Review on Applications of Time-Lapse Electrical Resistivity Tomography Over the Last 30 Years : Perspectives for Mining Waste Monitoring

Mining operations generate large amounts of wastes which are usually stored into large-scale storage facilities which pose major environmental concerns and must be properly monitored to manage the risk of catastrophic failures and also to control the generation of contaminated mine drainage. In this context, non-invasive monitoring techniques such as time-lapse electrical resistivity tomography (TL-ERT) are promising since they provide large-scale subsurface information that complements surface observations (walkover, aerial photogrammetry or remote sensing) and traditional monitoring tools, which often sample a tiny proportion of the mining waste storage facilities. The purposes of this review are as follows: (i) to understand the current state of research on TL-ERT for various applications; (ii) to create a reference library for future research on TL-ERT and geoelectrical monitoring mining waste; and (iii) to identify promising areas of development and future research needs on this issue according to our experience. This review describes the theoretical basis of geoelectrical monitoring and provides an overview of TL-ERT applications and developments over the last 30 years from a database of over 650 case studies, not limited to mining operations (e.g., landslide, permafrost). In particular, the review focuses on the applications of ERT for mining waste characterization and monitoring and a database of 150 case studies is used to identify promising applications for long-term autonomous geoelectrical monitoring of the geotechnical and geochemical stability of mining wastes. Potential challenges that could emerge from a broader adoption of TL-ERT monitoring for mining wastes are discussed. The review also considers recent advances in instrumentation, data acquisition, processing and interpretation for long-term monitoring and draws future research perspectives and promising avenues which could help improve the design and accuracy of future geoelectric monitoring programs in mining wastes.

Mapping the impact of a large municipal waste disposal area on surface water: 1993-2017, case of Laogang, Shanghai

In China, the impact of waste disposal facilities is always a cause of concern for the government and the public. Laogang Municipal Waste Disposal Area (LMDA), Shanghai, one of the largest municipal waste disposal areas in the world was selected as case in this study, and it was attempted to analyze the changes in the surface water quality, and map the impacted area by LMDA on surrounding streams from its operation period of 1993-2017. The results showed that, during the whole period, only biochemical oxygen demand (BOD₅) showed a continuous improvement with a percentage of 85.92%, however, chemical oxygen demand (COD_cr), ammonia (NH₄⁺-N) and total phosphorus (TP) significantly improved but BOD₅ slightly deteriorated began from 2013. Using spatial analysis tools and Kendall's concordance test, COD_cr and phenol at LMDA showed a significant impact on surrounding surface water; especially, the impacted area for COD_cr decreased from 106.30 km² to 22.86 km² from 1993 to 2017, which dropped from 4.3 to 0.9 times the area of LMDA. Surprisingly, NH₄⁺-N and TP at LMDA were affected by the surrounding streams, instead of having an impact on them. Interestingly, heavy metals and non-metals such as Hg, As, Zn, and Se in the surrounding streams were unlikely affected by LMDA. The driving forces for surface water quality improvement included the eco-remediation of closed unsanitary landfills, upgrade in waste shipping and terminals, operation of sanitary landfills and incineration plants for landfill diversion. Capsule: Impacted area of municipal waste disposal area is not so large.

Effective reuse of waste material as an amendment in composite landfill liner: Assessment of geotechnical properties and pollutant retention capacity

The effective reuse silica fume (S), a by-product from the silicon manufacturing industry, as an amendment in the composite landfill liner along with natural clay (C) and bentonite (B) was investigated in the present study. Experiments were conducted with various proportions of silica fume (10%-50%) to clay and bentonite to get mixtures C-B-S1 to C-B-S5. The study indicated significant improvement in the geotechnical and pollutant retention capacity by silica fume addition. The maximum dry density of the mixtures ranged from 1.568 to 1.732 g cm^-3. Permeability was in the order of C-B<C-B-S1 to C-B-S5<clay. Unconfined compressive strength of the C-B mix increased with the addition of silica fume from 10% to 25%, with a maximum value of 241.31 kPa. The free swell index decreased to 3.6 and the cation exchange capacity increased to 83 meq/100 g with the addition of 50% silica fume. The percentage removal of copper with C-B-S1 to C-B-S5 was 91.2%, 92%, 93.5%, and 95.2%, respectively, when the initial copper concentration was about 30 mg L^-1. Based on the assessment of geotechnical and pollution abatement capacity C-B-S3 with 25% silica fume addition was proposed as the composite liner material for the naturally available clay at the landfill site.

Monitoring of the process of waste landfill leachate diffusion in clay and sandy soil

The objective of this research was to evaluate the interaction of landfill leachate of urban solid waste in clayey (CL) and sandy soils (SL) in order to determine physical and chemical parameters that can be used as indicators of soil contamination when there are faults in the landfill waterproofing. In the diffusion tests, compacted soil samples were placed in contact with leachate (methanogenic phase). The temporal analysis (200 days) considered the parameters pH, electrical conductivity (EC), alkalinity, nitrogen series, chemical oxygen demand (COD), solids and color for the leachate and pH, ΔpH, EC, total nitrogen (TN), chemical elements, and cation exchange capacity (CEC) for the soils. Correlation analysis and principal component analysis (PCA) were performed to results. It was observed that the studied soils have potential to attenuate chemicals present in the leachate; this indicates the possibility of using them as base in landfills. Correlation analysis and PCA carried out to CL showed that in a process of CL monitoring the pH would be the key parameter to indicate contamination of this soil, due to the high correlation of this parameter with the others analyzed. For the SL, the parameters pH, alkalinity, apparent color, and COD (total and filtered) could be used as indicators of contamination. In both soils, monitoring of concentrations of Ca, Mg, K, SB, V, and CTC can be used to indicate possible faults in the waterproofing system of the landfill.