A Spatial Approach to Environmental Risk Assessment of PAH Contamination

Abstract

The extent of remediation of contaminated industrial sites depends on spatial heterogeneity of contaminant concentration and spatially explicit risk characterization. We used sequential Gaussian simulation (SGS) and indicator kriging (IK) to describe the spatial distribution of polycyclic aromatic hydrocarbons (PAHs), pH, electric conductivity, particle aggregate distribution, water holding capacity, and total organic carbon, and quantitative relations among them, in a creosote polluted soil in southern Sweden. The geostatistical analyses were combined with risk analyses, in which the total toxic equivalent concentration of the PAH mixture was calculated from the soil concentrations of individual PAHs and compared with ecotoxicological effect concentrations and regulatory threshold values in block sizes of 1.8 x 1.8 m. Most PAHs were spatially autocorrelated and appeared in several hot spots. The risk calculated by SGS was more confined to specific hot spot areas than the risk calculated by IK, and 40-50% of the site had PAH concentrations exceeding the threshold values with a probability of 80% and higher. The toxic equivalent concentration of the PAH mixture was dependent on the spatial distribution of organic carbon, showing the importance of assessing risk by a combination of measurements of PAH and organic carbon concentrations. Essentially, the same risk distribution pattern was maintained when Monte Carlo simulations were used for implementation of risk in larger (5 x 5 m), economically more feasible remediation blocks, but a smaller area became of great concern for remediation when the simulations included PAH partitioning to two separate sources, creosote and natural, of organic matter, rather than one general.

Mapping the Centimeter-Scale Spatial Variability of PAHs and Microbial Populations in the Rhizosphere of Two Plants

“…Geostatistical tools are also used to describe and establish spatial links between PAH contamination and soil physical, chemical and biological characteristics. Positive relationships between PAH hotspots and organic carbon concentrations [ 41 ], fungal biomass [ 42 ], bacterial diversity and ring-hydroxylating dioxygenase gene abundance [ 43 ], was established at the meter scale in aged-polluted soils. At finer (millimeter to centimeter) scale in urban roadside soil, the spatial heterogeneity of PAH-mineralization potential [ 3 ] was highlighted, but the distribution of PAHs and PAH-degraders was not correlated [ 44 ].…”

Characterization of Environmental Health Inequalities Due to Polyaromatic Hydrocarbon Exposure in France

“…The use of a random-forest regression has previously shown to be a more successful prediction method than multiple linear regression, in the mapping accuracy [36]. Moreover, physio-chemical soil properties have also been shown to influence the spatial distributions of the B[a]P [42]. The random-forest regression selected to fit the residuals before the spatial interpolation allowed to include the various variables in the model (soil properties, distance from polluted sites, indicator kriging result), in a more flexible framework than linear regression, which was usually used.…”

An Integrated Framework for Environmental Multi‐Impact Spatial Risk Analysis

“…There is increasing awareness in the risk and multicriteria decision analysis communities about the importance of the spatial dimension in environmental risk assessment. (2,3,9) This growing interest promoted the development of risk assessment models in many different areas of application, ranging from landslide susceptibility mapping, (10) to seismic hazard evaluation, (11) flood hazard zoning, (12,13) health diseases epidemics, (14) fire and phytosanitary risk management for plant species, (15) risk invasion for plant species, (16) fire risk, (2,(17)(18)(19) , earthquake hazards, (20) erosion risk, (21) ecological risk assessment, (22,23) and industrial contamination risk, (9,24) to name the most common ones.…”