Site-specific Ecological Risk Assessment Research Articles

National Decommissioning Research Initiative (NDRI) phase 2 determining outcomes to inform offshore decommissioning options

The Australian offshore oil and gas (O&G) industry is facing a significant decommissioning portfolio over the next few decades. In response to this, in 2019, eight Australian oil and gas operators and the National Energy Resources Australia (NERA) established the National Decommissioning Research Initiative (NDRI) with the aim to fill key knowledge gaps on the potential environmental impacts, risks and benefits of different decommissioning options in Australia’s offshore environment. In phase 1, seven research projects were undertaken covering the interaction that occurs between the environment and O&G infrastructure in Australia’s oceans. Phase 2 of the NDRI has now commenced with a focus on developing an ecological risk assessment guidance document for O&G titleholders to be able to undertake environmental risk assessments to determine if the level of contamination associated with different offshore decommissioning options is environmentally acceptable. The paper would describe the pathway to produce guidance on science-based acceptability criteria for contamination associated with O&G infrastructure: Research needed for the development of screening values to identify if a site-specific ecological risk assessment is required. Research plans are to be developed to identify the lines of evidence that can be used to determine if impacts and risks of any contamination are of an acceptable level. Ongoing engagement of regulators, researchers and other stakeholders is a critical component on the pathway forward.

Site-specific ecological risk assessment of metal-contaminated soils based on the TRIAD approach

Ecological risk assessment based on scientific data is crucial for understanding causal relationships between chemical pollution and environmental risks. Simultaneously, a balance is required between socioeconomic factors and scientific evidence. The TRIAD approach, which incorporates three lines of evidence (LoE)—chemical (Chem-LoE), ecotoxicological (Ecotox-LoE), and ecological (Eco-LoE)—was applied in five sites of an abandoned mine for site-specific soil ecological risk assessment (SERA). In combination, the three LoEs showed that two sites had extremely high risks, one site had moderate risk, and the other site had low risk. At all sites, Chem-LoE exhibited high-integrated risk values. In Ecotox-LoE and Eco-LoE, some species were not affected despite high metal concentrations in the soil samples collected from the sites, indicating that the bioavailability of metals differed according to the physiochemical properties of the soil medium. This study is significant as multiple analyses were performed considering ecosystem structure to reduce uncertainty in SERA. The results provide information to support effective decision-making risk management to protect the soil ecosystem. Moreover, these findings will be useful in establishing policies and priorities for soil risk management.

Site-Specific Soil Ecological Risk Assessment of a Metal Contaminated Area Based on the Triad Approach

Site-Specific Soil Ecological Risk Assessment of a Metal Contaminated Area Based on the Triad Approach

Screening level ecological risk assessment of abandoned metal mines using chemical and ecotoxicological lines of evidence

In the present study, a screening level site-specific ecological risk assessment (ERA) was conducted on 10 abandoned metal mines in Korea to determine the ecological risk and prioritize the mines requiring further investigation. A cost-saving approach was adopted by combining both the chemical (ChemLoE) and the ecotoxicological (EcotoxLoE) lines of evidence for the evaluation of integrated risk (IR), rather than applying the full spectrum of Triad, including ecological LoE. The risk values for ChemLoE were derived by calculating the toxic pressure based on the total and 0.01 M CaCl2 extractable metal(loid) concentrations. The risk values for EcotoxLoE were based on the mortality and reproduction of the collembolan species Paronychiurus kimi in the mine soils. A response surface model with a central composite design (CCD) was constructed to standardize the effects of soil physicochemical properties (i.e., organic matter content, clay content, and soil pH) on the reproduction of P. kimi. The predicted number of offspring was used as a reference for the calculation of risk value for reproduction. The ChemLoE and EcotoxLoE values ranged from 0.34 to 1.00 and 0.12 to 0.49, respectively, in the surveyed mines. The contribution of the ChemLoE value to the IR was higher than that of the EcotoxLoE value for all mines. Overall, two of the 10 mines were classified as high-risk soils with high IR values (IR > 0.76), but large deviations were also observed between the LoEs in these mines, suggesting the need for further studies to confirm the potential risks. The future investigations of these mines should focus particularly on providing additional evidence to reduce the degree of uncertainty for risk assessment.

Relevance of the bioavailable fraction of DDT and its metabolites in freshwater sediment toxicity: New insight into the mode of action of these chemicals on Dictyostelium discoideum

In this work, the toxicity of lake sediments contaminated with DDT and its metabolites DDD and DDE (collectively, DDX) was evaluated with widely used toxicity tests (i.e., Vibrio fischeri, Daphnia magna, Pseudokirchneriella subcapitata, and Lumbriculus variegatus) and with the social amoeba Dictyostelium discoideum, a model organism that is also suitable for studying pollutant-induced alterations at the molecular and cellular levels. Although the DDX concentration in the sediments was high (732.5 ppb), the results suggested a minimal environmental risk; in fact, no evidence of harmful effects was found using the different bioassays or when we considered the results of more sensitive sublethal biomarkers in D. discoideum amoebae. In line with the biological results, the chemical data showed that the concentration of DDX in the pore water (in general a highly bioavailable phase) showed a minimal value (0.0071ppb). To confirm the importance of the bioavailability of the toxic chemicals in determining their biological effects and to investigate the mechanisms of DDX toxicity, we exposed D. discoideum amoebae to 732.5ppb DDX in water solution. DDX had no effect on cell viability; however, a strong reduction in amoebae replication rate was observed, which depended mainly on a reduction in endocytosis rate and on lysosomal and mitochondrial alterations. In the presence of a moderate and transient increase in reactive oxygen species, the glutathione level in DDX-exposed amoebae drastically decreased. These results highlight that studies of the bioavailability of pollutants in environmental matrices and their biological effects are essential for site-specific ecological risk assessment. Moreover, glutathione depletion in DDX-exposed organisms is a new finding that could open the possibility of developing new pesticide mixtures that are more effective against DDT-resistant malaria vectors.

Ecological Risk Assessment of a Metal-Contaminated Area in the Tropics. Tier II: Detailed Assessment.

This study presents data on the detailed evaluation (tier 2) of a site-specific ecological risk assessment (ssERA) in a former smelter area contaminated with metals (Santo Amaro, Bahia, Brazil). Combining information from three lines of evidence (LoE), chemical (ChemLoE), ecotoxicological (EcotoxLoE) and ecological (EcoLoE), in the Triad approach, integrated risk values were calculated to rank sites and confirm the potential risk disclosed with tier 1. Risk values were calculated for the habitat and for the retention functions in each sampling point. Habitat function included the ChemLoE calculated from total metal concentrations. The EcotoxLoE was based on reproduction tests with terrestrial invertebrates (Folsomia candida, Enchytraeus crypticus, Eisenia andrei), shoot length and plant biomass (Avena sativa, Brassica rapa). For the EcoLoE, ecological parameters (microbial parameters, soil invertebrate community, litter breakdown) were used to derive risk values. Retention function included the ChemLoE, calculated from extractable metal concentrations, and the EcotoxLoE based on eluate tests with aquatic organisms (Daphnia magna reproduction and Pseudokirchneriella subcapitata growth). Results related to the habitat function indicated that the metal residues are sufficient to cause risk to biota, while the low metal levels in extracts and the general lack of toxicity in aquatic tests indicated a high soil retention capacity in most sampling points. Integrated risk of tier 2 showed the same trend of tier 1, suggesting the need to proceed with remediation actions. The high risk levels were related to direct toxicity to organisms and indirect effects, such as failure in the establishment of vegetation and the consequent loss of habitat quality for microorganisms and soil fauna. This study shed some light on the selection of tools for the tier 2 of an ssERA in tropical metal-contaminated sites, focusing on ecological receptors at risk and using available chemical methods, ecological surveys and ecotoxicity tests.

Soil invertebrate community change over fuel-contaminated sites on a subantarctic island: An ecological field-based line of evidence for site risk assessment.

A number of fuel spills, of both recent and historic origins, have occurred on World Heritage-listed subantarctic Macquarie Island. Sites contaminated by mainly diesel fuels are undergoing remediation by the Australian Antarctic Division. The risks posed by these sites are being managed using a "weight of evidence" approach, for which this study provides a preliminary line of evidence for the ecological assessment component of this site management decision framework. This knowledge is pertinent, given the absence of environmental guidelines for fuel contaminants in subantarctic ecosystems. We provide a field-based, site-specific ecological risk assessment for soil invertebrate communities across the fuel spill sites, before the commencement of in situ remediation activities. Springtails (Collembola) were the most abundant taxa. Springtail community patterns showed only limited correlations with the level of fuel contamination at the soil surface, even when elevated levels occurred in the substratum layers. Of the environmental variables measured, community patterns were most strongly correlated with vegetation cover. We identify a suite of 6 species that contribute most to the community dynamics across these sites. A subset of these we propose as useful candidates for future development of single-species toxicity tests: Folsomotoma punctata, Cryptopygus caecus, Cryptopygus antarcticus and Parisotoma insularis. Findings from this study advance our understanding of soil invertebrate community dynamics within these contaminated sites, directly contributing to the improved management and restoration of the sites. Not only does this study provide an important line of evidence for the island's ecological risk assessment for fuel contaminants, it also enhances our understanding of the potential impact of fuels at other subantarctic islands.

A site-specific ecological risk assessment for corn-associated insecticides.

A site-specific ecological risk assessment (ERA) was conducted to examine the simultaneous use of genetically modified corn (Bt corn) with a neonicotinoid seed coating, clothianidin, and use of a granular insecticide, tefluthrin, to protect crops from pest damage. A field study was conducted on site, and exposure data from the literature were summarized to determine the matrices and exposure concentrations that nontarget species could typically experience within an agricultural ecosystem. To determine ecological effects on nontarget species, acute toxicity bioassays were conducted on earthworms (Eisenia fetida), amphipods (Hyalella azteca), and Elmid riffle beetle larvae (Ancyronyx spp.) in which the test species were exposed to single insecticides as well as the mixture of the 3 insecticides. In the risk characterization section of the ERA, stressor-response profiles for each species tested were compared with field distributions of the insecticides, and a margin of safety at the 10th percentile (MOS10) was calculated to estimate risk. No acute toxicity was observed in any of the 3 nontarget species after exposure to senescent Bt corn leaf tissue. Large MOS10 values were calculated for clothianidin to the nontarget species. When bioassays were compared with tefluthrin field distributions, very low MOS10 values were calculated for earthworms (0.06) and H. azteca (0.08) because the environmental concentrations often exceeded the stressor-response profile. No increased toxicity was observed when nontarget species were exposed to a mixture of the 3 insecticides. In summary, the genetically modified corn insecticidal proteins and clothianidin were not found at environmental concentrations exceeding benchmark values for ecological effects, but tefluthrin was consistently detected in the environment at levels that could be causing toxicity to nontarget species, especially if this pyrethroid is able to travel off site.

Toxicity of phenmedipham and carbendazim to Enchytraeus crypticus and Eisenia andrei (Oligochaeta) in Mediterranean soils

PurposeThe main objective of the present study was to evaluate the toxicity of two reference chemicals, Carbendazim and Phenmedipham, for the compostworm Eisenia andrei (effects of Carbendazim) and the potworm Enchytraeus crypticus (effects of Phenmedipham) in 12 Mediterranean soils with contrasting soil properties. The observed toxicity was also compared to that obtained for OECD standard soil, used as a control.Materials and methodsThe soils were selected to be representative for the Mediterranean region and to cover a broad range of soil properties. The evaluated endpoints were avoidance behavior and reproduction. Soils were also assembled in two groups according to their pedological properties.Results and discussionToxicity benchmarks (AC50s) obtained for E. andrei avoidance behavior in carbendazim-contaminated soils were generally higher for sandy soils with low pH. The toxic effects on the reproduction of the compostworms were similar in the six tested soils, indicating a low influence of soil properties. The avoidance response of E. crypticus towards Phenmedipham was generally highly variable in all tested soils. Even though, a higher toxicity was observed for more acidic soils. The EC50s for reproduction of the latter species varied by a factor of 9 and Phenmedipham toxicity also tended to be increasing in soils with lower pH, except for the soils with extreme organic matter content (0.6 and 5.8%).ConclusionsA soil effect on chemical toxicity was clearly confirmed, highlighting the influence that test soils can have in site-specific ecological risk assessment. Despite some relationships between soil properties and toxicity were outlined, a clear and statistically significant prediction of chemical toxicity could not be established. The range of soil properties was probably narrow to give clearer and more consistent insights on their influence. For the four groups of tests, the toxicity observed for OECD soil was either similar, lower, or generally higher if compared with Mediterranean soils. Moreover, it did represent neither the organic matter content found in Mediterranean soils nor their textural classes.

Environmental risk assessment of a metal-contaminated area in the Tropics. Tier I: screening phase

Purpose The present study presents data on the screening phase (tier 1) of a site-specific ecological risk assessment in a former smelter area heavily contaminated with metals (Santo Amaro, Bahia, Brazil). Joining information from three lines of evidence (LoE), chemical, ecotoxicological, and ecological, integrated risk values were calculated to rank sites within the area and identify those that may need further investigation in tier 2.

Ecosystem impairment evaluation on biodiversity and functional diversity for contaminated soil assessment

A site-specific ecological risk assessment procedure for a qualitative evaluation of impairment occurring at the ecosystem level, as a result of soil contamination, was developed to integrate and visualize impairment in both terrestrial biodiversity and functional diversity and to support the decision maker in the contaminated site assessment. An Ecosystem Impairment Matrix (EcoIM) was proposed to identify the relationships between the applied measurement endpoints and the taxonomic groups living in the terrestrial system and between these taxonomic groups and the fundamental ecological processes. A specific impairment analysis procedure that used expert judgment allowed for the linking of impairment highlighted by the measurement endpoints with the terrestrial ecosystem's structure and functionality. Impairment occurring on each ecological element (i.e., biodiversity aspects and ecological functions and processes) was visualized by colored cells--1 for each relationship among measurement endpoint, taxonomic group, and ecological element--to support the expert in the ecosystem impairment evaluation. These results were then reported by the expert into the Global Ecosystem Impairment Evaluation Matrix (GEM) to summarize the obtained information and formulate a final judgment on ecosystem quality status. EcoIM and GEM were implemented in Module 2 of the decision support system DSS-ERAMANIA and are presented in this paper. The tools have been preliminarily applied to the Acna di Cengio (Italy) contaminated site; the results of this application are also presented and discussed.

The potential impact of a deep geologic repository for used nuclear fuel on non-human biota

This study presents and implements a screening methodology for assessing the potential postclosure radiological impact of a deep geological repository (DGR) for used nuclear fuel on non-human biota. This screening methodology is designed for hypothetical sites representative of selected Canadian conditions under both present and potential future climate conditions. The screening is carried out by comparing estimated radionuclide concentrations to derived “No Effect Concentrations” (NECs). The NECs are screening or threshold criteria; the conservative nature of the assumptions used to derive the NECs ensures that as long as the NECs are not exceeded, there is confidence that, despite uncertainty in modelled environmental concentrations, there will be no significant ecological effect on non-human biota. In the event NECs are exceeded in screening calculations, a site-specific Ecological Risk Assessment would be required to determine whether this is due to conservatism in the assumptions, lack of sufficient data or potential real impact. The NECs derived in this study were compared to other threshold criteria from U.S. and international literature.

Estimating the environmental impact of micro-pollutants in the low Ebro River (Spain): An approach based on screening toxicity with Vibrio fischeri

The aim of this study was to assess the likely impacts on the ecosystems due to agricultural, human, and industrial activities carried out in an ecologically important area of the Ebro River (Spain). For it, a screening site specific ecological risk assessment was conducted. Considering the presence of high levels of potentially toxic substances, such as metals and chlorinated organic compounds, aqueous and organic extracts were used to assess toxicity in sediments by using the photo-luminescent bacteria Vibrio fischeri (Microtox ®) as screening response variable. Sediment samples collected during 2005–2006 in the last course of the Ebro River and its Delta have been analyzed. Toxic responses have shown strong relationships to the levels of pollutants in the area. Moreover, various sites presented some toxicity level, probably because of other factors associated with reducing environments into the sediments. Results indicate that Microtox ® bioassay is an appropriate tool to perform risk assessment studies at screening level.

Development of a site-specific ecological risk assessment for contaminated sites: Part I. A multi-criteria based system for the selection of ecotoxicological tests and ecological observations

A two modules Decision Support System (DSS-ERAMANIA) was developed in order to support the site-specific Ecological Risk Assessment (ERA) for contaminated sites. Within the first module, the TRIAD and the Weight of Evidence approaches were used to develop a site-specific Ecological Risk Assessment framework including three tires of investigation. Selected ecological observations and ecotoxicological tests were compared according to Multi Criteria Decision Analysis (MCDA) methods and expert judgment, and the obtained ranking was used to identify a suitable set of tests, at each investigation tier, to be applied to the examined case study. A simplified application of the proposed methodology, implemented in the Module 1 of the DSS-ERA-MANIA, is described and discussed.

Development of a site-specific Ecological Risk Assessment for contaminated sites: Part II. A multi-criteria based system for the selection of bioavailability assessment tools

A comparison procedure based on Multi-Criteria Decision Analysis (MCDA) and expert judgment was developed in order to allow the comparison of bioavailability tests to implement the chemical Line of Evidence (LoE) within a TRIAD based site-specific Ecological Risk Assessment framework including three tires of investigation. The proposed methodology was included in the Module 1 of the Decision Support System DSS-ERAMANIA and the obtained rank supported the selection of a suitable set of available tests to be applied to the case study. A simplified application of the proposed procedure is described and results obtained by the system software are discussed.

Desenvolvimento de um Esquema para Avaliação de Risco Ecológico em Ambientes Tropicais: Estudo de Caso da Contaminação por Metais em Santo Amaro da Purificação, Bahia, Brasil

Development of a site specific ecological risk assessment scheme for tropical environments: a case study from Santo Amaro da Purificacao, Bahia, Brazil This project aims to further develop and adapt an ecological risk assessment scheme, following a tiered approach, for tropical systems. The study will be conducted in a metal contaminated area at Santo Amaro da Purificacao (Bahia, Brasil), resulting from the deposition of reminiscent metal waste of a lead smelter, inactive since 1993. The ecological risk will be evaluated joining information from three different lines of evidence: chemistry, ecology and ecotoxicology. The study includes the development and adaptation of terrestrial ecotoxicological bioassays for tropical environments that, together with bioassays with aquatic organisms, will allow an integrated assessment of both habitat and retention functions of the impacted soils. The final output of the project will be an environmental risk assessment scheme that will act as a base scheme for tropical environments with similar contamination profile.

Potential Use of the Plant Antioxidant Network For Environmental Exposure Assessment of Heavy Metals in Soils

In recent years, awareness has risen that the total soil content of pollutants by itself does not suffice to fully assess the potential ecotoxicological risks involved. Chemical analysis will require to be complemented with biological assays in a multidisciplinary approach towards site specific ecological risk assessment (SS-ERA). This paper evaluates the potential use of the plants' antioxidant response to metal-induced oxidative stress to provide a sensitive biological assay in SS-ERA. To this end, plants of Phaseolus vulgaris were grown for two weeks on 15 soils varying in contamination level. Morphological parameters and enzymatic plant responses were measured upon harvest. Foliar concentrations of the (heavy) metals Al, Cu, Cd, Cr, Fe, Mn, Ni, Pb, Zn were also determined. Metal mobility in the soil was further assessed by determining soil solution and NH4OAc extractable levels. In general more significant correlations were observed between plant responses and foliar metal concentrations or exchangeable/soluble levels than between plant responses and the total soil content. The study demonstrates the potential use of the plants' antioxidant defence mechanisms to assess substrate phytotoxicity for application in SS-ERA protocols. However, the system, based on calculation of a soil Phytotoxicity Index (PI), will require adaptation and fine-tuning to meet the specific needs for this type of environmental monitoring. Large variation was observed in phytotoxicity classification based on the various test parameters. The thresholds for classification of the various morphological and enzymatic response parameters may require adaptation according to parameter stress sensitivity in order to decrease the observed variation. The use of partial PI's (leaves and roots separately) may in addition increase the sensitivity of the system since some metals show specific effects in one of both organs only. Loss of biological functionality of enzymes, as was observed for ICDH in one of the more strongly contaminated soils, may also be recognized as an additional stress symptom when assigning phytotoxicity classification, whereas the current system only considers increasing enzymatic capacities. Other easily distinguishable parameters, which could be added to the current indexation are: failure to germinate and the incapacity to develop roots in the toxic substrate. Additional research will be required to determine the possible application range of soil properties for this biological assay and to further improve its performance in SS-ERA.

European Experience on Application of Site-Specific Ecological Risk Assessment in Terrestrial Ecosystems

ABSTRACT This article describes the current state of the development toward a common European framework for site-specific ecological risk assessment (SS-ERA) Although common progression has been slow in the past two years, earlier activities were very promising. Results are presented of a 2001 workshop to discuss the scientific development and policy needs in preparation of such a common framework. The framework was recommended to follow a tiered approach. Other important elements for a common European framework for SS-ERA were identified to be the use of generic values in the first tier and bioassays in later tiers, to address bioavailability in the assessment, to differentiate for land use. Also, the framework should allow for negotiation between stakeholders specific to the site. These aspects are present in the Dutch approach to SS-ERA, and this article further presents some experience with the application of this framework in a large case of SS-ERA in The Netherlands. The derivation of suitable ecological parameters and assessment criteria in view of land use in a tiered approach risk assessment is focused on, and the interactive process between stakeholders and ongoing discussions concerning references and criteria for assessment are illustrated.

The Bioavailability of Chemicals in Soil for Earthworms

AbstractFor Abstract see ChemInform Abstract in Full Text.

The bioavailability of chemicals in soil for earthworms

The bioavailability of chemicals to earthworms can be modified dramatically by soil physical/chemical characteristics, yet expressing exposure as total chemical concentrations does not address this problem. In order to understand the effects of modifying factors on bioavailability, one must measure and express chemical bioavailability to earthworms in a consistent, logical manner. This can be accomplished by direct biological measures of bioavailability (e.g., bioaccumulation, critical body residues), indirect biological measures of bioavailability (e.g., biomarkers, reproduction), or indirect chemical measures of bioavailability (e.g., chemical or solid-phase extracts of soil). If indirect chemical measures of bioavailability are to be used, they must be correlated with some biological response. Bioavailability can be incorporated into ecological risk assessment during risk analysis, primarily in the estimation of exposure. However, in order to be used in the site-specific ecological risk assessment of chemicals, effects concentrations must be developed from laboratory toxicity tests based on exposure estimates utilizing techniques that measure the bioavailable fraction of chemicals in soil, not total chemical concentrations.