Environmental assessment of the effects of a municipal landfill on the content and distribution of heavy metals in Tanacetum vulgare L

A review towards developing a hierarchical model for sustainable hospital solid waste management in rural areas of Zimbabwe

Management of solid waste from rural hospitals is amongst problems affecting Zimbabwe due to diseases, population, and hospital increase. Solid waste from rural hospitals is receiving little attention translating to environmental health problems. Therefore, 101 secondary sources were used to write a paper aiming to proffer a hierarchical model to achieve sustainable solid waste management at rural hospitals. Rural hospitals' solid waste encompasses electronic waste, sharps, pharmaceutical, pathological, radioactive, chemical, infectious, and general waste. General solid waste from rural hospitals is between 77.35 and 79% whilst hazardous waste is between 21 and 22.65%. Solid waste increase add burden to nearly incapacitated rural hospitals. Rural hospital solid waste management processes include storage, transportation, treatment methods like autoclaving and chlorination, waste reduction alternatives, and disposal. Disposal strategies involve open pits, open burning, dumping, and incineration. Rural hospital solid waste management is guided by legislation, policies, guidelines, and conventions. Effectiveness of legal framework is limited by economic and socio-political problems. Rural hospital solid waste management remain inappropriate causing environmental health risks. Developed hierarchical model can narrow the route to attain sustainable management of rural hospitals' solid waste. Proposed hierarchical model consists of five-layered strategies and acted as a guide for identifying and ranking approaches to manage rural hospitals' solid waste. Additionally, Zimbabwean government, Environmental Management Agency and Ministry of Health is recommended to collaborate to provide sufficient resources to rural hospitals whilst enforcing legal framework. Integration of all hierarchical model's elements is essential whereas all-stakeholder involvement and solid waste minimisation approaches are significant at rural hospitals.

Bioavailability and health risk of pollutants around a controlled landfill in Morocco: Synergistic effects of landfilling and intensive agriculture

Toxic contamination of agricultural soils by trace metal(oid)s can pose detrimental effects on human health and agroecological systems. In this view, the current research explored total and available metal(oid)s in surface soils and assessed the associated hazards using pollution indices, PMF modeling, PCA, and Montecarlo probabilistic human risk assessment with 10,000 repetitions. The mean concentrations of Cd, Pb, As, Cr, Ni, Cu, Zn, and Fe were 0.89, 24.86, 1.81, 19.10, 25.44, 7.98, 49.12 and 6183.32 mg kg-1 dry weight, respectively. These findings highlighted that the concentration of pollutants exceeded the values measured in the geochemical background. Soil enrichment by heavy metal (oid)s was confirmed by analyzing available fractions using DTPA ,CaCl2 and enrichment factor (EF). Additionally, pollution indicators (Igeo, PLI, and PERI) displayed significant contamination levels, with a higher ecological risk. Matrix Factorization (PMF) receptor and multivariate statistical analysis reflected that anthropogenic activities, particularly landfilling and agricultural practices were the main causes of the contamination. Furthermore, probabilistic and deterministic human risk assessments showed that carcinogenic risks exceeded the threshold values (10-4) set by the USEPA. Consequently, it is crucial to implement continuous monitoring and supervision of landfill sites to prevent additional pollution. These measures should be integrated into the management plans for waste management.

Pollution characteristics and microbial community succession of a rural informal landfill in an arid climate

Informal landfills pose potential threats to the environment and human health due to the lack of anti-seepage measures. However, little research has been conducted on the distribution of pollutants in informal landfill sites situated in arid climates, as well as the underlying interaction mechanisms between environmental factors and microbial structure. In this study, we sought to investigate the pollution characteristics and microbial community succession of the landfill in northern China. The results revealed that heavy metals in the landfill showed poor mobility and migration. The lower layers of the garbage samples had higher water-soluble contents of heavy metals compared to the upper layers. The landfill-derived dissolved organic matter (DOM) was found to originate from microbial production, and four fluorescent components were identified, including fulvic acid-like substances, humus-like substances, and protein-like components. Fluorescence intensity and humification degree increased with increasing depth. The microbial diversity and richness decreased with sampling depth. The most abundant phyla in the samples were Proteobacteria, unidentified_Bacteria, Bacteroidota, Firmicutes, Myxococcota, Gemmatimonadota, Actinobacteria, and Deinococcota. As the sampling depth increased, Proteobacteria decreased, while Bacteroidota and Firmicutes showed a remarkable increase, with little variation observed in the other phyla. The partial least-squares path model (PLS-PM) results indicated that pH had the most significant effect on microbial abundance and diversity (direct effect value = -5.560), while DOM and heavy metals had the opposite effect, with direct effects of 1.838 and 3.231, respectively. DOM was identified as the driving factor for the variation in other environmental factors. The redundancy analysis (RDA) showed that the dominant genera were greatly influenced by Cu, humic-like substances, and protein-like substances. Among them, Bacillus, Alcanivorax, Devosia, and Chryseolinea may play important roles in the remediation of landfills. Our study not only gains a deeper understanding of the pollution risk of informal landfills in arid climates, but also provides a scientific basis for the future treatment and restoration of contaminated sites associated with landfills.

Soil contamination by trace metals and assessment of the risks associated: the dumping site of Safi city (Northwest Morocco)

The main objective of this work was to determine the soil contamination with trace metals within and around the dumpsite of Safi city (Morocco) and to evaluate the potential environmental risk associated. The results showed that the average soil concentrations of trace metals had the following order: Fe > Zn > Cu > Cr > Cd and exceeded the world and the upper continental background concentrations except for Fe. In addition, the concentrations of Zn, Cu, and Cd remained beyond the limit standards given by the WHO/FAO. Geoaccumulation index, enrichment factor, and pollution load index (PLI) indicated that the dumpsite soil is highly contaminated and deteriorated, presenting evidence of high ecological risk proved by the values of the potential ecological risk index (PERI). Correlation analyses revealed a strong relationship between the organic matter & [Fe, Zn, Cr, Cd], calcium carbonates & [Zn, Cr], and Cr & Cu inside the dumpsite soil. Principal component analysis confirmed the temporal and spatial classification of Zone A as the oldest and Zone C as the youngest and indicated that the regrouped trace metals could have the same behavior and or the same origin. The interpolation of trace metals concentrations and PERI revealed a plausible extension outside the landfill, confirmed by PLI values.

Assessment of potentially toxic metal(loid)s contamination in soil near the industrial landfill and impact on human health: an evaluation of risk

The generation of solid waste is increasing with each passing day due to rapid urbanization and industrialization and has become a matter of concern for the international community. Leachate leakages from landfills pollute the soil and can potentially harm the human health. In this paper, inductively coupled plasma-optical emission spectrometric studies were employed to assess and analyze the composition of metals (Ba, Cd, Pb, Hg, Cu, Cr and Mn) and metalloid (As) in soil samples. Results of Cr, Mn, Cu, As, Ba, Cd, Pb and Hg from CRM (certified reference material, SRM 2709a) of San Joaquin soil were evaluated and reported in terms of percent recoveries which were in the range of 97.6-102.9% and show outstanding extraction efficiency. Other than copper, where the permitted limit set by the EU is specified as 50-140 mg/kg in soil, the average amount of all the metals in soil was found within the permissible limits provided by WHO, the European Community (EU) and US EPA. Soil contaminated with Hg (PERI = 100) and Cd (PERI = 145.50) posed an ecological risk significantly. Pollution load index (PLI) value is greater than 1, while degree of contamination (Cdeg) value is less than 32 which indicated that the soil is polluted and considerably contaminated with metals and metalloid, respectively. In terms of the average daily dosage (ADD) of soil, children received the highest doses of all metals (ADDing = 1.315 × 10-7 - 2.470 × 10-3 and ADDderm = 9.939 × 10-7 - 5.292 × 10-11), whereas ADDing (1.409 × 10-8 - 2.646 × 10-4) was found greater in adults. For all metals except for Ba, the hazard quotient (HQ) trend in both children and adults was observed to be HQing > HQderm > HQinh of soil. Children who are at the lower edge of cancer risk had a lifetime cancer risk (LCR) of 2.039 × 10-4 for Cr from various paths of soil exposure.

Characteristics of leachate from refuse transfer stations in rural China

The properties of leachate from refuse transfer stations (RTSs) in rural China were indefinite. In this study, a total of 14 leachate samples from RTSs in nine provinces of China were characterized for their pH, electric conductivity, chromaticity, concentration of organic substances, nitrogen distribution, volatile organic compounds (VOCs), organic phosphorous pesticide, and heavy metals. The structural composition of fluorescent dissolved organic matter (FDOM) was also determined. To evaluate the leachate pollution potential in this study, a leachate pollution index was derived and used. Chromium (Cr) was the most polluting heavy metal present in rural leachate. Ethanol and ethyl acetate were the most frequently detected VOCs at high concentrations. Three-dimensional fluorescence excitation-emission matrix spectra were used to characterize the FDOM. Three components, tryptophan (C₁), tyrosine-like (C₂), and humic acid- and fulvic acid-like (C₃) substances, were identified from all 14 samples. Tryptophan was the major component of FDOM and present in 45.7% of the samples by calculating the fluorescence intensity percentage, on average. Pearson correlations revealed that the fluorescence intensity of C₁ and C₃ was strongly related to soluble chemical oxygen demand and dissolved oxygen carbon, while C₂ had significant positive correlations with ammonia nitrogen and total phosphorus of the solid waste. This study provided detailed data and findings that could serve as a preliminary basis for broadening options for the treatment and management of leachate from rural RTSs in China.

Evaluation and environmental risk assessment of heavy metals in the soil released from e-waste management activities in Lahore, Pakistan

In developing regions, electronic waste either gets recycled by using crude and primitive techniques in recycling centers or dumped in dumping grounds that result in the leaching of heavy metals into the ambient environment. The objective of this study is to determine the concentration of heavy metals (Cu, Pb, Zn, Cd, Mn, and Fe) in the surface soil of recycling centers and dumping sites in Lahore, Pakistan, and to quantify and compare the environmental risk. The mean concentration (mg/kg) of Cu, Pb, Zn, and Cd was 722.96, 446.81, 378.76, and 4.11, respectively in the surface soil of recycling centers, and only the mean concentration of Cu (214.09 mg/kg) from dumping sites were above permissible limits of World Health Organization. Results of the geo-accumulation index (Igeo) and contamination factor (Cf) revealed that the surface soil is highly contaminated with Cu, Pb, and Cd. The Cd content (701.24) caused a very high potential ecological risk (Er) (> 320) to nearby biological communities. The noncarcinogenic risk was only expected from Pb to children (1.70) living near recycling centers, whereas no risk was observed for adults living either near recycling centers (0.23) or dumping sites (0.01). There is a high probability of carcinogenic health risks to children (1.085 × 10^-2) and adults (1.195 × 10^-3) from Cu. Hence, all the results suggest that e-waste recycling and dumping activities were a significant source of heavy metals to the surrounding environment, children, and adults, so it is strongly recommended to take action for sustainable management of e-waste.

Medicinal Plant Growth in Heavy Metals Contaminated Soils: Responses to Metal Stress and Induced Risks to Human Health

Accelerating heavy metal pollution is a hot issue due to a continuous growth in consumerism and increased activities in various global industries. Soil contamination with heavy metals has resulted in their incorporation into the human food web via plant components. Accumulation and amplification of heavy metals in human tissues through the consumption of medicinal plants can have hazardous health outcomes. Therefore, in this critical review we aim to bring together published information on this subject, with a special highlight on the knowledge gaps related to heavy metal stress in medicinal plants, their responses, and human health related risks. In this respect, this review outlines the key contamination sources of heavy metals in plants, as well as the absorption, mobilization and translocation of metal ions in plant compartments, while considering their respective mechanisms of detoxification. In addition, this literature review attempts to highlight how stress and defensive strategies operate in plants, pointing out the main stressors, either biotic or abiotic (e.g., heavy metals), and the role of reactive oxygen species (ROS) in stress answers. Finally, in our research, we further aim to capture the risks caused by heavy metals in medicinal plants to human health through the assessment of both a hazard quotient (HQ) and hazard index (HI).

An overview of the environmental pollution and health effects associated with waste landfilling and open dumping

Landfilling is one of the most common waste management methods employed in all countries alike, irrespective of their developmental status. The most commonly used types of landfills are (a) municipal solid waste landfill, (b) industrial waste landfill, and (c) hazardous waste landfill. There is, also, an emerging landfill type called "green waste landfill" that is, occasionally, being used. Most landfills, including those discussed in this review article, are controlled and engineered establishments, wherein the waste ought to abide with certain regulations regarding their quality and quantity. However, illegal and uncontrolled "landfills" (mostly known as open dumpsites) are, unfortunately, prevalent in many developing countries. Due to the widespread use of landfilling, even as of today, it is imperative to examine any environmental- and/or health-related issues that have emerged. The present study seeks to determine the environmental pollution and health effects associated with waste landfilling by adopting a desk review design. It is revealed that landfilling is associated with various environmental pollution problems, namely, (a) underground water pollution due to the leaching of organic, inorganic, and various other substances of concern (SoC) contained in the waste, (b) air pollution due to suspension of particles, (c) odor pollution from the deposition of municipal solid waste (MSW), and (d) even marine pollution from any potential run-offs. Furthermore, health impacts may occur through the pollution of the underground water and the emissions of gases, leading to carcinogenic and non-carcinogenic effects of the exposed population living in their vicinity.

Urbanization influences the distribution, enrichment, and ecological health risk of heavy metals in croplands

The contamination of urban soils with heavy elements due to the rapid development of urbanization and urban services has become a major environmental and human health challenge. This study provides insight into the urbanization controls on combined pollution severity and health risk potential of heavy metals in corn-cultivated urban versus non-urban soils. A multifaceted assessment was conducted using enrichment factor (EF), ecological risk (ER), bioconcentration factor (BCF), transmission factor (TF), hazard index (HI), and carcinogenic risk (CR). The results indicate a significant increase in the concentration of all metals in urban farmlands. When compared to the non-urban soils, EF implies a significant increase of all metals in the urban soil, downgrading this index from minimal enrichment (EF < 2) in the control soils to moderate enrichment (2 ≤ EF < 5) in the urban soils. Likewise, the average ER value showed an increase in the urban soils than in the control soils in the order of Fluvisols (66.6%) > Regosols (66.1%) > Cambisols (59.8%) > Calcisols (47%). The BCF and TF values for different elements decreased in the order of Cd (0.41-0.92) > Cu (0.1-0.23) > Zn (0.1-0.18) > Ni (0.01-0.03) > Pb (0.005-0.011) and Zn (0.75-0.94) > Cu (0.72-0.85) > Pb (0.09-0.63) > Cd (0.17-0.22) > Ni (0.01-0.21), respectively, which indicates that certain metals were not mobilized to the extent that they had been accumulated in the plant roots. The total carcinogenic risk was ranged from 5.88E-05 to 1.17E-04 for children and from 1.17E-04 to 2.30E-04 for adults, which implies a greater associated health risk for children.

Environmental risk assessment and factors influencing heavy metal concentrations in the soil of municipal solid waste landfills

The environmental risk assessment and the factors influencing heavy metals (HM) in the soil at the municipal solid waste landfill sites (MSWLs) were studied by literature review, field survey, and statistical methods. The results indicated that the dominant HM contamination in the soil at the MSWLs was caused by chromium (Cr) with the Nemero index values (PI) from 22.7 to 44.3 and zinc (Zn) with the PI from 0.7 to 9.8. There were significant differences in the Cr, mercury (Hg), lead (Pb), Zn, and arsenic (As) concentrations between soil samples from sanitary and non-sanitary landfills (NSLs) where HM contamination (PI = 10.9) was more obvious. As (CRA_As = 2.35 × 10^-4) and cadmium (Cd) (CRA_Cd = 1.45 × 10^-4) posed potential carcinogenic health effects. The soil Cd concentration had a significant negative correlation (r = -0.476^**) with the landfill age. The soil As concentration had a significant positive correlation (r = 0.472^**) with rainfall in NSLs. There were significant differences in the As (P = 0.042) and copper (Cu) (P = 0.042) concentrations between soil samples from the surrounding areas of MSWLs and the base where soil had higher HM concentrations. For the efficient prevention of HM ecological risk, a scientific site selection, undamaged coverage and anti-seepage systems, standardized management, and ongoing monitoring are required.

Current Status and Review of Waste-to-Biogas Conversion for Selected European Countries and Worldwide

Growing world population and increasing population density are leading to increasing waste production with biological waste amounting to several billion tonnes annually. Together with the increasing need for renewable energy sources, waste-to-biogas conversion as a prime example of waste-to-energy technology represents a facile way of solving two problems simultaneously. This review aims to address the recent progress in the field of waste-to-biogas technology, which is lately facing intensive research and development, and present the current status of this waste treatment method both in technological and legislative terms. The first part provides an overview of waste and waste management issues. This is followed by a detailed description of applicable waste-to-energy (WtE) technologies and their current implementation in selected European countries. Moreover, national energy and climate plans (NECPs) of selected EU Member States are reviewed and compared with a focus on implementation of WtE technologies. In a further section, biogas production from waste around the world is reviewed and compared country wise. Finally, an outlook into the future of WtE technologies is provided alongside the conclusions based upon the reviewed data.

Occurrence and spatial distribution of heavy metals in landfill leachates and impacted freshwater ecosystem: An environmental and human health threat

Municipal landfill leachates are a source of toxic heavy metals that have been shown to have a detrimental effect on human health and the environment. This study aimed to assess heavy metal contamination in leachates, surface water, and sediments from non-sanitary landfills in Uyo, Nigeria, and to identify potential health and environmental effects of leachate contamination. Over the wet and dry seasons, surface water and sediment samples were collected from an impacted freshwater ecosystem, and leachates samples from six monitoring wells. Elemental analyses of samples were conducted following standard analytical procedures and methods. The results indicated that leachate, surface water, and sediment samples all had elevated levels of heavy metals, implying a significant impact from landfills. Pollution indices such as the potential ecological risk index (PERI), pollution load index (PLI), degree of contamination (Cd), modified degree of contamination (mCd), enrichment factor (EF), geoaccumulation index (Igeo), and Nemerov pollution index (NPI) were used to assess the ecological impacts of landfill leachates. The following values were derived: PERI (29.09), PLI (1.96E-07), Cd (0.13), mCd (0.16), EF (0.97-1.79E-03), Igeo (0), and NPI (0.74). Pollution indicators suggested that the sediment samples were low to moderately polluted by chemical contaminants from the non-sanitary landfills, and may pose negative risks due to bioaccumulation. Human health risks were also assessed using standard risk models. For adults, children, and kids, the incremental lifetime cancer rate (ILCR) values were within the acceptable range of 1.00E-06-1.00E-04. The lifetime carcinogenicity risks associated with oral ingestion exposure to heavy metals were 9.09E-05, 1.21E-05, and 3.60 E-05 for kids, adults, and children, respectively. The mean cumulative risk values for dermal exposures were 3.24E-07, 1.89E-06, and 1.17E-05 for adults, children, and kids, respectively. These findings emphasized the risks of human and biota exposure to contaminants from landfills.

Progress and prospects in mitigation of landfill leachate pollution: Risk, pollution potential, treatment and challenges

The escalating loads of municipal solid waste (MSW) end up in open dumps and landfills, producing continuous flows of landfill leachate. The risk of incorporating highly toxic landfill leachate into environment is important to be evaluated and measured in order to facilitate decision making for landfill leachate management and treatment. Leachate pollution index (LPI) provides quantitative measures of the potential environmental pollution by landfill leachate and information about the environmental quality adjacent to a particular landfill. According to LPI values, most developing countries show high pollution potentials from leachate, mainly due to high organic waste composition and low level of waste management techniques. A special focus on leachate characterization studies with LPI and its integration to treatment, which has not been focused in previous reviews on landfill leachate, is given here. Further, the current review provides a summary related to leachate generation, composition, characterization, risk assessment and treatment together with challenges and perspectives in the sector with its focus to developing nations. Potential commercial and industrial applications of landfill leachate is discussed in the study to provide insights into its sustainable management which is original for the study.

Assessment of Physicochemical Groundwater Quality and Hydrogeochemical Processes in an Area near a Municipal Landfill Site: A Case Study of the Toluca Valley

Sanitary landfills are considered one of the main sources of contamination of water resources due to the generation of leachate with a high content of dissolved organic matter (DOM), inorganic material, and toxic elements. This study aimed to determine the influence of leachate on the physicochemical quality and hydrogeochemical processes which determine the chemical composition of groundwater in an area near a municipal sanitary landfill site. In situ parameters (pH, temperature, electrical conductivity, dissolved oxygen, ORP), physicochemical parameters (HCO₃⁻, PO₄³⁻, Cl⁻, NO₃⁻, SO₄²⁻, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺), and dissolved organic matter were analyzed. The content of dissolved organic matter (DOM) was determined by 3D fluorescence microscopy. The presence of Cl⁻, NO₃⁻, NH₄⁺, PO₄³⁻, BOD, and COD indicated the presence of contamination. The significant correlation between NO₃⁻ and PO₄³⁻ ions (r = 0.940) and DOM of anthropogenic origin in the 3D fluorescence spectra confirm that its presence in the water is associated with the municipal landfill site in question. The type of water in the area is Mg-HCO₃, with a tendency to Na-HCO₃ and Na-SO₊-Cl. The water-rock interaction process predominates in the chemical composition of water; however, significant correlations between Na⁺ and Ca²⁺ (r = 0.876), and between K⁺ and Mg²⁺ (r = 0.980) showed that an ion exchange process had taken place. Likewise, there is enrichment by HCO₃⁻ and SO₄²⁻ ions due to the mineralization of the organic matter from the leachate. The groundwater quality that supplies the study area is being affected by leachate infiltration from the sanitary landfill.

Toxic and heavy metals contamination assessment in soil and water to evaluate human health risk

Due to urbanization and industrialization, there has been an increase in solid waste generation and has become a global concern and leakage of leachate from landfills contaminate the soil and groundwater and hence can have a severe impact on human health. The present study aimed to determine the composition of toxic metals (Cr, Mn, Cu, As) and heavy metals (Cd, Ba, Hg, Pb) in soil and water by an inductively coupled plasma optical emission spectrometer (ICP-OES). To ensure accuracy during the analysis of Cr, Mn, Cu, As, Cd, Ba, Hg, and Pb in real samples, certified reference material (CRM, SRM 2709a) of San Joaquin soil and water (SRM 1640a) were analyzed and results were presented in terms of % recovery studies. The mean concentration of all the metals in soil and water did not exceed the limit set by the European Community (EU), WHO, and US EPA except Cu where the permissible limit defined by the EU is 50-140 mg/kg in soil. The soil is uncontaminated to moderately contaminated with respect to all metals except the Cu and Pb. Among the average daily dose (ADD) of soil, ADDing and ADDinh for children had the maximum dose for all metals than adults while ADDderm was higher in adults. Hazard quotient (HQ) trend in both adults and children was found in order HQing > HQderm > HQinh of soil for all metals except Ba which followed HQing > HQinh > HQderm. Hazard index (HI) values of soil for Cr and Pb in children were 7 and 7.5 times higher than adults respectively. Lifetime cancer risk (LCR) value for Cr by different exposure pathways of soil was 5.361 × 10-4 for children which are at the lower borderline of risk for cancer.

Evaluation of mercury bioavailability to vegetables in the vicinity of cinnabar mine

Knowledge of the concentration of the bioavailable forms of mercury in the soil is necessary, especially, if these soils contain above-limit total mercury concentrations. The bioavailability of mercury in soil samples collected from the vicinity of abandoned cinnabar mines was evaluated using diffusive gradients in the thin films technique (DGT) and mercury phytoaccumulation by vegetables (lettuce, spinach, radish, beetroot, carrot, and green peas). Mercury was accumulated primarily in roots of vegetables. The phytoaccumulation of mercury into edible plant parts was site-specific as well as vegetable species-specific. The mercury concentration in edible parts decreased in the order: spinach leaf ≥ lettuce leaf ≥ carrot storage root ≥ beetroot storage root > radish storage root > pea legume. The translocation index as well as the target hazard quotient indicate the possible usability of soils from the vicinity of abandoned cinnabar mines for planting pod vegetables (peas). A strong positive correlation (r = 0.75 to 0.92, n > 30, p < 0.05) was observed between mercury concentration in secondary roots, the storage roots, leaves of vegetables and the flux of mercury from soil to the DGT units, and the effective concentration of mercury in soil solutions.

Degradation of soil quality by the waste leachate in a Mediterranean semi-arid ecosystem

The assessment of soil quality indices in waste leachate-affected soils is vital to understand the threats of land quality degradation and how to control it. In this respect, a study was conducted on the effects of uncontrolled landfill leachate on soil quality index (SQI) in calcareous agricultural lands using 28 soil variables. Using the total data set (TDS) and minimum data set (MDS) approaches, the SQI was compared between leachate-affected soils (LAS) and control soils by the integrated quality index (IQI) and nemoro quality index (NQI) methods. The results revealed that LAS were significantly enriched by soil salinity-sodicity indices including electrical conductivity (EC), sodium adsorption ratio (SAR), and exchangeable sodium percentage (ESP), fertility indices including total N, available P and K, organic carbon, and cation exchange capacity (CEC), exchangeable cations (Ca, Mg, K, and Na), the available and total fractions of heavy metals (Zn, Cu, Cd, Pb, Ni). After the leachate got its way into the soil, the values of IQI and NQI were dropped ranging 5-16% and 6.5-13% for the TDS approach and 5-15.2% and 7.5-12.2 for the MDS approach, respectively. Clearly, the data showed that soil quality degradation was encouraged and stimulated by the leachate. Among the different models of SQI applied in the present study, IQI determined by MDS was the optimal model to estimate soil quality and predict crop yields given the analysis of the correlations among the SQI models, the correlations between the SQI models and wheat yield, and sensitivity index values.

Heavy metals in leachate, impacted soils and natural soils of different landfills in Malaysia: An alarming threat

Landfills are a potential threat to human health and the environment, especially from the detrimental and toxic heavy metals. This study focuses on the assessment of heavy metals contamination in leachate and surface soils from different landfills in Malaysia. Maximum quality rating scale (QRS) values of As (787) and Cr (552) denotes progressive deterioration of leachate contamination in landfill. The impacted soils showed high heavy metal concentrations especially at non-sanitary unlined landfills, as compared to background values, and natural soil nearby the landfills. In addition, to examine the environmental impacts of the landfill area (soil) in more detail, specific indexes; geo-accumulation index (Igeo), pollution index (PI) and integrated pollution index (IPI) were determined. Maximum As (3.122) and Cd (2.633) for Igeo and As (34.037) and Cd (20.881) for PI revealed that the soil samples in non-sanitary landfills were moderate to strongly polluted. The difference in range of IPI values for sanitary (0.294-0.322) and non-sanitary landfill soils (1.263-1.956) confirmed advanced decline of the soil quality in non-sanitary landfills. Arsenic concentrations were found to be statistically significant (ANOVA) for leachate and impacted soil in landfills investigated. It is also important to realize that rise in metal contents in landfill environments were not only caused by anthropogenic sources such as from the waste disposed, but also some other factors such as redox conditions, anoxic environments, pH, oxidation state of metals and microbial activities. Those conditions will actively promotes leaching of metals from waste and also natural soils in the landfill.

Recycling of Organic Wastes through Composting: Process Performance and Compost Application in Agriculture

Composting has become a preferable option to treat organic wastes to obtain a final stable sanitized product that can be used as an organic amendment. From home composting to big municipal waste treatment plants, composting is one of the few technologies that can be practically implemented at any scale. This review explores some of the essential issues in the field of composting/compost research: on one hand, the main parameters related to composting performance are compiled, with especial emphasis on the maturity and stability of compost; on the other hand, the main rules of applying compost on crops and other applications are explored in detail, including all the effects that compost can have on agricultural land. Especial attention is paid to aspects such as the improvement of the fertility of soils once compost is applied, the suppressor effect of compost and some negative experiences of massive compost application.

Lead Tolerance and Enrichment Characteristics of Several Ornamentals Under Hydroponic Culture

The growth response, tolerance, and enrichment characteristics of six ornamental species, Chlorophytum comosum, Calendula officinalis, Iris lacteal, Belamcanda chinensis, Saponaria officinalis, and Polygonum lapathifolium were studied under hydroponic culture with lead (Pb) concentrations ranging from 0 to 1000 mg/L. The results showed that the growth of the tested ornamental species under Pb stress was inhibited. Belamcanda chinensis presented the largest tolerance index (0.75), and Calendula officinalis had the highest toxicity threshold (500 mg/L) under Pb stress. The highest Pb contents in the shoots were detected in Iris lacteal and Belamcanda chinensis. The enrichment coefficients in the shoots of Iris lacteal and Belamcanda chinensis were significantly higher than those in the other ornamental species. In conclusion, Iris lacteal and Belamcanda chinensis are the most tolerant and have the greatest Pb enrichment and translocation abilities under Pb stress, and thus, they have a strong potential to restore Pb-contaminated water bodies and soils.

Contamination, ecological and health risks of trace elements in soil of landfill and geothermal sites in Tibet

Due to the utilization of landfill technology and geothermal energy production in Tibet, the contamination of the soils and underground water by trace element has currently become a serious problem, both ecologically and to the human health point of view. However, relevant studies concerning this critical problem, particularly in the Tibet area has not been found. Therefore, this study investigated the soil contamination and the spatial distribution of the trace elements in the areas surrounding the Tibetan landfill sites (LS) and geothermal sites (GS) through several pollution evaluation models. In addition, the possible sources of trace elements and their potential impact on public health were also investigated. Results showed that the trace elements in soils nearby LS and GS had moderate to high contamination risk. In soils surrounding LS, mercury had the highest concentration of 0.015 mg/kg and was 6 times higher than the background value of 0.008 mg/kg while in GS, arsenic had the highest concentration of 66.55 mg/kg, and exceeded the soil contamination risk value of 25 mg/kg. Maizhokunggar LS was the most polluted site with an average pollution load index value of 2.95 compared to Naqu, Nyingchi, Shigatse, and Lhasa. 42% of LS were with considerable ecological risk, and all GS had low ecological risk. Both carcinogenic and non-carcinogenic risk for children and adults (male, female) were within the acceptable range. According to the source analysis, unscientific anthropogenic activities including accumulated MSW, industrial discharges, and vehicle emissions significantly contributed 51.83% to soil trace element contamination. Considering that Tibet is an environment-ecologically vulnerable region with very weak self-adjustment ability, accumulated municipal solid waste in the landfill sites should be well disposed of, and even soil remediation should be well implemented.

Using Mosses as Bioindicators of Potentially Toxic Element Contamination in Ecologically Valuable Areas Located in the Vicinity of a Road: A Case Study

This study analyzed the impact of road transportation on the concentration of Zn, Ni, Pb, Co, and Cd in moss (Pleurozium schreberi). The study was carried out over five years near a national road running from the north to the east (Poland) in the area of Natura 2000 sites. Samples were collected at three significantly different locations: (1) near a sharp bend, (2) near a straight section of the road in a woodless area, and (3) in a slightly wooded area. At each location, moss samples were collected from sites situated 2, 4, 6, 8, 10, 12, and 14 m from the road edge. The highest Zn and Cd contents in the moss were recorded 6 m from the road edge near a sharp bend (where vehicles brake sharply and accelerate suddenly). At the same location, at a distance of 2 m, the highest Pb concentration was noted, and at a distance of 4 m from the road, the highest Ni concentration was noted. The Co concentration in the moss was the highest near the woodless straight section at a distance of 2 and 12 m from the road. The concentrations of Zn, Pb, Ni, Co (only at the woodless location), and Cd (at all locations) were significantly and negatively correlated with distance from the road.

Impact of the uncontrolled leakage of leachate from a municipal solid waste landfill on soil in a cultivated-calcareous environment

The heavy metal pollution generated by landfill leachate becomes increasingly concerning due to its potential to impact human health through the food chain. In the present study, the accumulation and potential health risk of heavy metals (Zn, Cu, Cd, Pb, and Ni) were investigated in a calcareous soil -wheat system affected by an uncontrolled landfill leachate. The results showed soils were significantly enriched by both the available and total fractions of the metals in the sequences of Zn > Pb > Ni > Cd > Cu and Cd > Zn > Ni > Pb > Cu, respectively. Nevertheless, only the Cd content exceeded the standard levels. For the various population groups, the mean hazard quotient (HQ) was lower than the unity, implying a lack of non-carcinogenic health risk for the local residents, while the average hazard index (HI) was 2.3 and 1.1 for people aged 0-5 and 6-18 years, respectively, illustrating a moderate non-carcinogenic health risk for the two groups. Cd and Pb contributed the most to HI, followed by Cu, Zn, and Ni. In addition, the carcinogenic health risk of Cd, ranging from 1 × 10^-5 to 1 × 10^-6, showed a low potential risk in the different population groups exposed to wheat grains and decreased in the sequence of adult > population 6-18 years > population 0-5 years. The findings of the study, which can be used in regions under similar environmental conditions, provide a valuable benchmark for the design of appropriate strategies to manage these agroecosystems by both local and national managers of such macrosystems.

Environmental risk assessment and consequences of municipal solid waste disposal

Effective and efficient assessments of the site conditions are required for the sustainable management of landfills. In this study we propose an evaluation method to determine the degree of environmental contamination by the contest of heavy metals (HM) concentrations in soil and plants (Tanacetum vulgare L., Carduus L., Plantago major L.). We compared HM concentrations in the soil, leaves, stem and roots of those native plants. Content of HM in samples was at the same level in all localities, except content of Zn. These values confirm that the area is not naturally burdened by increased HM content in the soil, and also that the deposited municipal waste or the material used for reclamation and composting does not contain risk elements. The content of selected HM was monitored in plants naturally occurring in the area of interest. We can state that the content of individual HM was in the plant biomass at the same level. The measured values confirmed that the largest number of HM was in roots, then in stem and the least in leaves. In addition, specific indexes were determined: BAC, TF, CF, PLI and I_geo. The BAC values confirmed that the individual plants had the ability to accumulate Pb and Cd (BAC> 2) but were limited to bind Mn and Zn (BAC <1). TF values confirmed that plants had a different ability to transport HM from roots to aboveground biomass. Potential soil contamination was detected using CF, PLI and I_geo indexes but contamination by HM was not confirmed.

An Analysis of the Risk Posed by Leachate from Dumpsites in Developing Countries

The disposal of municipal solid waste into primarily dumpsites in developing countries causes a number of potential public and environmental health risks. While there have been various studies that have evaluated the contaminants that cause the risks, these studies have generally not examined in a holistic way the manner in which these contaminants move. This study therefore sought to model the flow of a range of contaminants in dumpsites (As, Cd, Cu, Pb, Ni, Zn), and potential health risks as a means of enabling the more effective siting of facilities to reduce the risks posed. The study proposes a conservative model, using well consolidated equations and assumption, taking into account the path the pollutant makes to reach the water table and the point of exposure. The modelling may be useful to easily identify the boundaries of the area of risk related to the presence of a dumpsite in a Developing Country, beyond which a local community may use or build a safe well for drinking water. The results show as the area of risk is large and varies significantly with changes in input parameters, suggesting that without site-specific information it is better to follow conservative assumptions.

Effects of open dumping of MSW on metal contamination of soil, plants, and earthworms in Ranchi, Jharkhand, India

Influence of open dumping of municipal solid wastes (MSW) on metal contamination of soil, plants, and earthworms in Ranchi, Jharkhand, India, was studied over 6-month period. Dumpsite in the study area exists in two sections, old section where waste dumping has stopped and new section where wastes are currently disposed. Soil around dumpsite had high concentration of Co, Cr, Cu, Pb, and Zn than that at control site. Geoaccumulation index indicated uncontaminated to moderate level of soil contamination at old dumpsite and soil at new dumpsite was found to be uncontaminated. Parthenium hysterophorus, Lantana camara, and Calotropis procera were the main plants found in patchy distribution around dumpsite. Plants exhibited almost similar levels of metal concentration in roots and shoots. P. hysterophorus and L. camara showed high bioaccumulation capacity and low translocation capacity. C. procera showed moderate bioaccumulation capacity and high translocation capacity as the concentration of metals was higher in the shoot. P. hysterophorus and L. camara due to higher bioaccumulation capacity and lower translocation capacity appear to be suitable for phytostabilization of metal-contaminated soil. Earthworms present at the dumpsite showed high concentration of Cr, Cu, Pb, and Zn with bioconcentration factor > 1. Results highlights that soil contamination due to metals is occurring at the dumpsite which is also leading to transfer of metals to plants and earthworms which can pose serious risk to environment and human health. The plants identified can be used for decontamination of metals from the dumpsite.

Phytostabilization-Management Strategy for Stabilizing Trace Elements in Contaminated Soils

Contamination of soil by copper (Cu) has become a serious problem throughout the world, causing the reduction of agricultural yield and harmful effects on human health by entering the food chain. A glasshouse pot experiment was designed to evaluate the potential use of halloysite as an immobilizing agent in the aided phytostabilization of Cu-contaminated soil, using Festuca rubra L. The content of Cu in plants, i.e., total and extracted by 0.01 M CaCl₂, was determined using the method of spectrophotometry. Cu content in the tested parts of F. rubra differed significantly when halloysite was applied to the soil, as well as with increasing concentrations of Cu. The addition of halloysite significantly increased plant biomass. Cu accumulated in the roots, thereby reducing its toxicity to the aerial parts of the plant. The obtained values of bioconcentration and translocation factors observed for halloysite treatment indicate the effectiveness of using F. rubra in phytostabilization techniques.