Key Takeaways & Executive Findings
- •• • Pb, Ni, and Cd exceeded risk screening values at 4.26%, 6.38%, and 4.26% of sampling points, respectively, indicating localized contamination requiring targeted remediation. • • Geo-accumulation indices for all eight metals were below 0 (mean < 0), confirming overall clean soil, but Pb, Zn, Ni, Hg, and Cd showed slight pollution at specific points, necessitating hotspot management. • • Monte Carlo simulation quantified that children had a 0.2% probability of non-carcinogenic risk and a 3.21% probability of unacceptable carcinogenic risk, while adults had 0.64% probability of carcinogenic risk, with Ni as the main contributor, highlighting the need for child-specific protection measures. • • Sensitivity analysis identified skin adherence factor as highly sensitive for both adults and children, and As, Pb, and Ni as major contributors, guiding priority monitoring and risk mitigation strategies.
Abstract
The accumulation of heavy metals in soil around municipal solid waste landfills poses potential risks to human health. This study selected a municipal solid waste landfill and monitored the concentrations of eight heavy metals (Zn, Pb, Cd, Ni, Hg, Cu, As, Cr) in surrounding soil. The geo-accumulation index method was used for pollution assessment, and a health risk assessment model recommended by the USEPA, combined with Monte Carlo uncertainty analysis, was employed to evaluate the pollution status and health risks to nearby residents. Results showed that among the eight metals, Pb, Ni, and Cd exceeded risk screening values at 4.26%, 6.38%, and 4.26% of sampling points, respectively. Geo-accumulation indices indicated overall clean conditions (mean < 0), but slight pollution by Pb, Zn, Ni, Hg, and Cd at some points. Probabilistic risk assessment based on Monte Carlo simulation revealed that for both adults and children, the cumulative non-carcinogenic risk was negligible, while carcinogenic risk was acceptable. However, there was a very low probability (approximately 0.2%) of non-carcinogenic risk for children, and probabilities of unacceptable carcinogenic risk were 0.64% for adults and 3.21% for children. Nickel was the primary contributor to carcinogenic risk, and children faced higher health risks than adults. These findings provide a reference for pollution prevention and health risk management of soil around municipal solid waste landfills.
1. Introduction
Landfills remain a primary disposal route for municipal solid waste, yet their long-term operation often leads to leakage of leachate, contaminating surrounding soil and groundwater with heavy metals. These metals, including Zn, Pb, Cd, Ni, Hg, Cu, As, and Cr, can accumulate in crops and enter the human body via ingestion, dermal contact, and inhalation, posing chronic health risks such as neurological damage, carcinogenicity, and organ toxicity. Traditional deterministic health risk assessments, while widely used, fail to account for variability in exposure parameters and contaminant concentrations, often leading to over- or under-estimation of risks. This uncertainty hampers effective risk management and remediation prioritization.
To address this bottleneck, the present study integrates Monte Carlo simulation with the USEPA health risk model, enabling probabilistic risk characterization and sensitivity analysis. This approach captures the full distribution of potential risks, identifies key contributing metals and exposure pathways, and provides a more realistic basis for decision-making. By applying this methodology to a landfill site in Hainan, China, we quantify both carcinogenic and non-carcinogenic risks for adults and children, offering actionable insights for targeted pollution control and public health protection.
Loading authentic research manuscript (Pages 1–5)...
QIN Mengyuan, HE Qiuping, CHEN Dan, MEN Ruixue, JIA Lijuan, MA Linzhuan (2026). Health Risk Assessment of Heavy Metals in Soil Around a Landfill Based on Monte Carlo Simulation. Chinese Journal of Environmental Engineering. https://doi.org/10.12030/j.cjee.202507021
Research & Educational Purpose Only: The translations, structured abstracts, analytical annotations, and data reports provided by SinoGreenTechare intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoGreenTech claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What are the main exposure pathways and which one dominates for both adults and children?
The three exposure pathways are ingestion, dermal contact, and inhalation. For both adults and children, the order of contribution is ingestion > dermal contact > inhalation, as indicated by the risk assessment results.
Which heavy metal is the primary contributor to carcinogenic risk, and what is its exceedance rate?
Nickel (Ni) is the primary contributor to carcinogenic risk. Ni exceeded the risk screening value at 6.38% of sampling points, the highest among the metals that exceeded screening values.
How does the Monte Carlo simulation improve the health risk assessment compared to deterministic methods?
Monte Carlo simulation accounts for uncertainty and variability in exposure parameters and contaminant concentrations, providing a probability distribution of risk rather than a single point estimate. This allows for quantifying the likelihood of exceeding risk thresholds, such as the 0.64% and 3.21% probabilities for adults and children, respectively, for unacceptable carcinogenic risk.
What are the implications of the sensitivity analysis for risk management?
Sensitivity analysis identified skin adherence factor as highly sensitive for both adults and children, and As, Pb, and Ni as major contributors. This suggests that reducing dermal contact through protective measures and focusing monitoring and remediation efforts on these metals would be most effective in mitigating health risks.
Are there any limitations to the study that could affect the generalizability of the findings?
The study is site-specific, focusing on one landfill in Hainan, China. The risk estimates depend on local soil background values and exposure parameters, which may differ in other regions. Additionally, the analysis considers only eight heavy metals and does not account for potential synergistic effects or other contaminants. Therefore, extrapolation to other sites should be done with caution.
Related Chinese Research & Cross-Citations
Analysis of National and Local Policies for Medical Waste Treatment and Disposal in China
The escalating generation of medical waste, driven by healthcare expansion and frequent medical activities, poses significant environmental and public health risks. Under the framework of ecological civilization, China is developing a comprehensive policy system for medical waste treatment and disposal, yet the current framework remains nascent and exhibits inconsistencies between national and local policies. This study systematically analyzes the status of national and local policies from 2003 to 2024, collecting 413 policy documents (166 from national ministries and 247 from provincial governments). The analysis examines temporal evolution, regional distribution, and policy focus, alongside the influence of medical waste output, treatment technologies, facility infrastructure, and major epidemic responses. Findings reveal distinct policy phases: initial self-disposal, exploratory management, foundational system building, and rapid development. Regional disparities are pronounced, with eastern coastal areas showing more advanced policies due to greater technical and financial resources. The surge in medical waste, particularly during the COVID-19 pandemic, underscores the need for enhanced regulatory guidance. Non-incineration technologies are gaining traction for their environmental and cost benefits, and facility coverage has improved but remains uneven. The study proposes five policy principles to foster technological innovation and industrial upgrading, ensuring safe medical waste management and environmental protection.
Kinetic Analysis and Simulation of Pollutant Removal in Sewage Networks
This study investigates pollutant removal characteristics and kinetic behaviors in sewage networks, and analyzes their impact on the carbon-to-nitrogen ratio (C/N, as COD/TN) of influent to wastewater treatment plants. Source water quality sampling at drainage outlets revealed spatial and temporal variations in C/N, with domestic sewage exhibiting higher C/N than industrial sewage, and diurnal peaks reaching 6.92 versus 4.71 during off-peak hours. Using a pilot-scale adjustable sewage network system in Kunshan, experiments were conducted under high (0.491 m·s−1) and low (0.089 m·s−1) flow velocities, monitoring pollutant removal over 144 hours. Pseudo-first-order kinetics were applied to model COD and TN removal. Results showed that COD (including SCOD and PCOD), BOD5, and SS achieved approximately 80% removal within 144 h, with higher removal at low flow velocity. TN, NH3-N, and TP exhibited lower overall removal rates. Kinetic fitting revealed that COD removal rate constants (kCOD) were significantly higher than those for TN (kTN), and both decreased with increasing flow velocity: at low velocity, kCOD=0.0167 h−1 and kTN=0.0029 h−1; at high velocity, kCOD=0.0127 h−1 and kTN=0.0020 h−1. Simulations based on actual source pollutant concentrations indicated that the time for C/N to drop to the denitrification critical value of 4.50 was 12.24 h at high velocity, but shortened to 9.49 h at low velocity. These findings demonstrate that increasing flow velocity effectively retards the decline of C/N. Therefore, regulating network flow velocity to reduce hydraulic retention time is a key strategy for maintaining adequate C/N at the terminal and ensuring denitrification efficiency in wastewater treatment plants.
Preparation of Trimetallic-Carbon Composite Catalysts and Their Application in Catalytic Ozonation of Industrial Wastewater
Advanced oxidation processes (AOPs) are promising for degrading organic pollutants in water treatment. Heterogeneous catalytic ozonation (HCO) has gained attention due to its high oxidation efficiency, strong interference resistance, and low secondary pollution. In this study, a series of trimetallic-carbon composite ozone catalysts were prepared via an organic precursor calcination method using γ-Al2O3 as support. This method enhanced catalytic activity and mechanical strength while overcoming the limitations of carbon materials (low mechanical strength) and metal-based materials (poor mass transfer). The optimized catalyst, CA-FeCoCu, comprising Fe, Co, Cu, carbon, and alumina, exhibited excellent performance in phenol degradation and real industrial wastewater treatment. Characterization revealed that the synergistic effect of trimetals and the introduction of multiple carbon types increased specific surface area and hydroxyl radical (·OH) generation. In a pilot-scale fixed-bed reactor, the CA-FeCoCu/O3 system reduced COD from 120 mg·L−1 to below 40 mg·L−1, with an O3 consumption ratio (O/C) of less than 1, effectively lowering operational costs. This work provides a new strategy for developing efficient and stable heterogeneous O3 catalysts and offers a reference for the practical application of HCO in industrial wastewater treatment.
Differentiated Characteristics of Suspended Particulate Matter and Their Effects on Water Quality in the Middle and East Routes of the South-to-North Water Diversion Project
This study investigates the spatiotemporal differentiation of suspended particulate matter (SPM) characteristics, sources, and their impacts on water quality between the Middle Route (closed artificial channel) and East Route (open natural water system) of the South-to-North Water Diversion Project. Thirty sampling sites (13 on the Middle Route, 17 on the East Route) were established, and samples were collected during dry and wet seasons. Water quality parameters and SPM characteristics were analyzed, including particle size distribution, total suspended solids (TSS), chlorophyll a, and stable carbon and nitrogen isotopes. Results show that the Middle Route maintains good and stable water quality, with SPM dominated by coarse particles (>63 μm, 61.43%–94.68%), total phosphorus (TP) <0.01 mg·L−1, and a significant positive correlation between chlorophyll a and coarse particles (r=0.60), indicating algal aggregation dominates particle formation. In contrast, the East Route exhibits high and fluctuating nitrogen and phosphorus concentrations, with SPM dominated by fine particles (<20 μm, 51.26%–88.61%), TP ranging from 0.03 to 1.11 mg·L−1, and a positive correlation with fine particles, suggesting significant external inputs. Carbon and nitrogen isotope analysis reveals that Middle Route SPM primarily originates from autochthonous algae (contribution >46.75%), while East Route SPM is influenced by both terrestrial C3 plants and algae. The distinct engineering and management approaches of the two routes lead to significant differences in SPM characteristics and sources, thereby affecting water quality dynamics. The Middle Route requires an 'algal reduction and hydrodynamic optimization' strategy to control algal-derived coarse particle deposition, whereas the East Route benefits from 'retention-sedimentation and wetland purification' to reduce external fine particles and pollutant inputs. This research provides theoretical support and practical guidance for differentiated SPM management in long-distance water diversion systems.
Combined Ozone Micro-Nano Bubble Oxidation and Powdered Activated Carbon Adsorption for Removal of Taste and Odor Compounds from Drinking Water
Algal-derived taste and odor compounds (2-methylisoborneol, 2-MIB, and geosmin, GSM) in drinking water sources are poorly removed by conventional treatment. This study systematically evaluated the standalone and combined performance of ozone micro-nano bubbles (O3-MNBs) oxidation and powdered activated carbon (PAC) adsorption for removing 2-MIB, GSM, and algal cells from source water. Results showed that O3-MNBs pre-oxidation achieved >97.5% removal of odorants at 400 ng·L−1 and 67.2% algal cell removal within 30 min. When applied as a deep treatment stage, the degradation rate constant (k) was 10.1%–25.6% higher than in pre-oxidation due to lower background matrix interference. Both pre-oxidation and deep treatment reduced effluent concentrations of 2-MIB and GSM to below 10 ng·L−1, with oxidation kinetics fitting pseudo-first-order models (R²>0.95). PAC adsorption of both compounds followed pseudo-second-order kinetics (R²>0.99), with GSM equilibrium adsorption capacity approximately 20.0% higher than that of 2-MIB. In pure water, adsorption capacity increased by >10.0% compared to raw water. Based on kinetic models, a quantitative prediction method was established for O3-MNBs oxidation and PAC adsorption processes, aiming to achieve efficient odorant removal and cost optimization, providing theoretical support for advanced drinking water purification and smart water plant construction.
Pulsed Electric Field Enhancement of Nitrogen Removal Performance and Microbial Community Structure Response in Anammox Granular Sludge
This study investigated the effects of a ring-shaped pulsed electric field (PEF) (1.5 V, 4 h on-time per cycle) on nitrogen removal performance and microbial community structure of anammox granular sludge (AnGS). Two anaerobic sequencing batch reactors (R1 control, R2 with PEF) were operated under stepwise increasing nitrogen loading rates (NLR). At NLR below 1,155 mg·(L·d)−1, R2 exhibited total nitrogen removal efficiency (TRE) 7.5%–17.0% higher than R1, with biomass, specific anammox activity (SAA), and extracellular polymeric substances (EPS) increased by 5%–7%, 21%–71%, and 54%–77%, respectively. However, at NLR above 1,320 mg·(L·d)−1, the toxic effect of nitrite dominated, and PEF enhancement diminished or even reversed to inhibition. Microbial community analysis revealed that at low-to-moderate NLR, PEF increased the relative abundance of Planctomycetes and key anammox bacteria (Candidatus Brocadia and Candidatus Jettenia), along with enhanced community richness (Chao1) and diversity (Shannon/Simpson indices). At high NLR, PEF decreased microbial richness compared to R1. Principal component analysis and redundancy analysis indicated that PEF was the key factor driving community differences at low-to-moderate NLR, whereas nitrite concentration became the dominant factor at high NLR. This study provides theoretical support for enhancing the resilience and engineering application of anammox processes.