Soil and Land Contamination
Soil and land contamination is the presence of hazardous substances in soil and the subsurface at levels that pose a risk to health or the environment.
Definition
The accumulation in soil or the subsurface of substances, typically from human activity, at concentrations that exceed natural background and may harm human health, ecosystems, or groundwater.
Scope
This area covers the contamination of soil, sediment, and groundwater by industrial chemicals, metals, hydrocarbons, and persistent organic pollutants. It addresses the chemistry of how contaminants partition, sorb, and migrate in the subsurface, the assessment and risk evaluation of contaminated sites, and the redevelopment of degraded land. Remediation methods are introduced under remediation technologies, and broader soil chemistry and hydrogeology under soil and water science.
Sub-topics
Core questions
- How do contaminants enter and persist in soil and the subsurface?
- What controls the mobility and bioavailability of soil contaminants?
- How are contaminated sites assessed and their risks evaluated?
- How is degraded or brownfield land returned to productive use?
Key theories
- Sorption and partitioning in soils
- The distribution of a contaminant between soil solids and pore water is governed by sorption processes described by partition coefficients, which determine how strongly contaminants are retained versus how readily they migrate to groundwater.
- Metal speciation and bioavailability
- The chemical form of a metal, set by pH, redox, and complexation, controls its solubility, mobility, and bioavailability, so total concentration alone is an incomplete measure of risk in contaminated soils.
Clinical relevance
Soil and land contamination can expose people through ingestion, inhalation of dust, food-chain uptake, and groundwater pathways; characterizing contaminant behavior underpins risk assessment, land-use decisions, and the prioritization of cleanup.
Evidence & guidelines
Contaminated-land work commonly applies risk-based assessment frameworks that compare measured concentrations with health- and environment-based screening values; these are described here to explain the assessment process rather than as fixed standards.
History
Public attention to contaminated land followed episodes such as Love Canal in the late 1970s, which spurred legislation on hazardous-waste sites and the development of systematic site-assessment and risk-based cleanup approaches.
Related topics
Seminal works
- manahan2017
- alloway2013
- sparks2003
Frequently asked questions
- Why does total contaminant concentration not fully indicate risk?
- Risk depends on how mobile and bioavailable a contaminant is, which is governed by its chemical form and by soil conditions such as pH and redox; a strongly bound contaminant may pose less immediate hazard than a smaller, more mobile fraction.
- What is a brownfield?
- A brownfield is previously developed land, often former industrial or commercial property, whose reuse is complicated by real or perceived contamination and which typically requires assessment and remediation before redevelopment.