Triad-based screening risk assessment of the agricultural area exposed to the long-term PAHs contamination

Abstract

The aim of the study was ecological risk assessment (ERA) of the agricultural soils located in the vicinity of the highly industrialized area and exposed to different emission sources of polycyclic aromatic hydrocarbons (PAHs). In this study, we demonstrated the combination of generic and site-specific ERA approach for screening assessment and delineation of the area of a high ecological risk. Generic approach was based on a hazard quotient and indicated that 62% of the research area needs further assessment. For site-specific evaluation, the Triad approach was utilized. Information from three lines of evidence (LoE): chemical, ecotoxicological and ecological, was integrated into one environmental risk (EnvRI) index. The chemical risk was derived from toxic pressure coefficients based on the total PAHs concentration. The ecotoxicological LoE included an acute toxicity testing: the luminescent bacteria Aliivibrio fischeri activity in both liquid- and solid-phase samples and the ability of crustacean Thamnocephalus platyurus to food uptake. The ecological LoE comprised microbial parameters related to soil respiration and enzymatic activity. Integrated EnvRI index ranged from 0.44 to 0.94 and was mainly influenced by high values of chemical LoE risk, while the ecotoxicological and ecological LoE indicated no or low risk. Due to the relatively high uncertainty associated with the contradictory information given by LoEs, there is the need to confirm potential risk in a tier 2 analysis.

Screening Risk Assessment of Agricultural Areas under a High Level of Anthropopressure Based on Chemical Indexes and VIS-NIR Spectroscopy

“…However, in 75% of soils, TN did not exceed 1.4 g kg −1 , and C org was below 17.6 g kg −1 , which corresponds to the lower range according to the European Union criteria [ 33 ]. The low content of organic matter and clay promotes the increase in contaminant availability, which may result in disturbance of soil functions and create risk to soil organisms [ 11 ].…”

“…According to these criteria, 78% of soil samples should be classified as contaminated to varying degree, with PAH concentrations ranging from 1000 to 5000 µg kg −1 in 50% of samples, and PAH > 5000 µg kg −1 in 12% of samples. The highest PAH levels were found in the samples from central and north parts of the Czerwionka region and might be attributed to PAH emission sources: historical long-term coke production and coal mining, and nowadays production of bituminous products, waste recovery, high traffic volume and house heating [ 11 ].…”

“…According to Polish guidelines, the acceptable maximum permissible concentration (MPC) for Anth, Ch, IndPyr and BPer is 200 μg kg −1 , while for Napht, BaA, BbF, BkF, BaPyr and DahA, the MPC is 100 μg kg −1 . HQ values of individual PAH compound > 1 indicate a possible ecological risk [ 11 , 17 , 49 ]. Average HQ value of a single chemical (expressed as median) varied significantly depending on PAH compound from 0.06 for Anth to 1.32 for BbF ( Table 2 ), what allows us to conclude that according to individual PAH, 7 to 62% of the study area might be under ecological risk (HQ above 1), and needs further actions (e.g., site-specific evaluation or remediation).…”

“…To reflect the potential risk caused by PAHs mixture the hazard index (HI) was additionally calculated, and to assess the degree of potential risk the approach of Moreno-Jiménez et al [ 17 ] was used. As a threshold value for HI index above which the possible risk occurs—the value of 10 was assigned [ 11 , 14 ]. Obtained HI values ranged between 1.56 and 1523 ( Table 2 ) but exceeded the threshold for HI only in 23% of soil samples from the study region.…”

“…PAH-contaminated agricultural soils have attracted considerable public attention since they can contaminate food, which is a threat to human health. Therefore, the identification and remediation of contaminated sites is of increasing importance [ 3 , 11 ]. The need for remediation is evaluated through decision-support systems based on assessment of the risk to human health, the soil ecosystem and food safety.…”