Wang et al. 2023 — Heavy metal distribution in industrial zone soils, Hangzhou, China
This study characterised heavy metal concentrations, spatial distribution, sources, and ecological and human health risks in soils of the key industrial zones of Hangzhou, Zhejiang Province, eastern China. A total of 2,651 soil surface samples were collected from 180 enterprises across chemical engineering, pharmacy, printing/dyeing, electroplating, and papermaking industries. Positive matrix factorization (PMF) analysis attributed 84.6% of soil HM pollution to human activities and 15.6% to natural sources, with Cd (PERI: 323.4) identified as the main ecological pollution risk element. Carcinogenic and non-carcinogenic risk indices were generally within acceptable ranges, with the notable exception of Cr in some sample clusters, though health risks were below regulatory thresholds for most sites.
Key numbers
Mean concentrations (mg/kg): As 13.2, Cr 2.35, Cu 39.6, Pb 46.1, Hg 0.12, Ni 36.7, Cd 1.66, Sb 0.28. Background values (Zhejiang Province): As 5.93, Cr 53.7, Cu 22.5, Pb 28.3, Hg 0.128, Ni 23.7, Cd 0.154, Sb 0.69. Mean contamination factor (CF) relative to background: As 2.34, Cr 0.04, Cu 1.76, Pb 1.63, Hg 0.94, Ni 1.55, Cd 10.8 (highest), Sb 0.41. Cd exceeded background by 10.78×, As by 1.42–10.78×. Cd range: not detected (ND) to 889 mg/kg, mean 1.66 mg/kg. Total PERI 407.54 (high ecological risk); Cd PERI 323.4 (dominant). Cd samples where RSV (65 mg/kg for development land, GB36600-2018) was exceeded: approximately 4.9%. PMF source contributions: 84.6% human activities, 15.6% natural.
Methods (brief)
2,651 surface soil samples collected October–November 2018 from 180 enterprises in Hangzhou industrial zones. Air-dried, 2-mm sieve. HNO3–HClO4–HF digestion for Cr, Cu, Pb, Cd, Ni (ICP-MS, Agilent 7850). HNO3/HCl (1:3) digestion for As, Sb, Hg (atomic fluorescence spectrometry). Standard reference materials GSS-1 and GSS-4, recoveries 85–110%. PMF 5.0 (US EPA). SPSS 22.0 statistical analysis; ArcGIS 10.2 for spatial distribution. Health risk assessment: oral ingestion and dermal pathways (USEPA Health Risk Handbook).
Limitations
Industrial zone soils only; not representative of agricultural soils used for food production in Hangzhou. The study area encompasses relocated enterprise sites, complicating current-risk interpretation. No food-crop measurements; soil Cd of mean 1.66 mg/kg would require plant-bioavailability corrections to estimate dietary exposure. Very wide Cd range (ND to 889 mg/kg) indicates extreme hotspots associated with specific enterprise types (electroplating, etc.).
Implications
- Certification: Directly relevant as supply-chain context: Hangzhou is a major food manufacturing and processing hub in eastern China. Soil contamination near relocated enterprises poses risk to any peri-urban agricultural production in the area. Cd enrichment at 10.8× background from industrial activity is a cautionary input for any supply-chain sourcing from Hangzhou’s agricultural periphery.
- Courses: Demonstrates how industrial enterprise clustering creates localised Cd hotspots (ND to 889 mg/kg range) that dwarf background and agricultural contamination, and how PMF source attribution can separate anthropogenic from geological inputs.
- App: Hangzhou-origin agricultural ingredients (vegetables, tea) may carry elevated Cd risk if grown near industrial zones; geographic_breakdown context for ingredients sourced from Zhejiang Province.
- Microbiome: Not applicable.