Scenario-targeted toxicity assessment through multiple endpoint bioassays in a soil posing unacceptable environmental risk according to regulatory screening values

A New Method for Ecological Risk Assessment of Combined Contaminated Soil

Ecological risk assessment of combined polluted soil has been conducted mostly on the basis of the risk screening value (RSV) of a single pollutant. However, due to its defects, this method is not accurate enough. Not only were the effects of soil properties neglected, but the interactions among different pollutants were also overlooked. In this study, the ecological risks of 22 soils collected from four smelting sites were assessed by toxicity tests using soil invertebrates (Eisenia fetida, Folsomia candida, Caenorhabditis elegans) as subjects. Besides a risk assessment based on RSVs, a new method was developed and applied. A toxicity effect index (EI) was introduced to normalize the toxicity effects of different toxicity endpoints, rendering assessments comparable based on different toxicity endpoints. Additionally, an assessment method of ecological risk probability (RP), based on the cumulative probability distribution of EI, was established. Significant correlation was found between EI-based RP and the RSV-based Nemerow ecological risk index (NRI) (p < 0.05). In addition, the new method can visually present the probability distribution of different toxicity endpoints, which is conducive to aiding risk managers in establishing more reasonable risk management plans to protect key species. The new method is expected to be combined with a complex dose-effect relationship prediction model constructed by machine learning algorithm, providing a new method and idea for the ecological risk assessment of combined contaminated soil.

Supported-catalyst CuO/AC with reduced cost and enhanced activity for the degradation of heavy oil refinery wastewater by catalytic ozonation process

In this work, activated carbon-supported copper(II) oxide (CuO/AC) was prepared and used to degrade heavy oil refinery wastewater (HORW) by catalytic ozonation with the aim to develop low-cost and high-efficient supported-catalysts for degrading real recalcitrant industrial wastewater. Supported-catalyst CuO/AC was characterized by X-ray diffraction (XRD), N₂-physisorption, scanning electronic microscope (SEM), transmission electron microscope (TEM), and X-ray fluorescence (XRF). The degradation was mainly evaluated by chemical oxygen demand (COD), total organic carbon (TOC), 5-day biochemical oxygen demand (BOD₅), biodegradability and toxicity. Compared with unsupported-catalyst CuO or the mixed system of activated-AC and unsupported-catalyst CuO, supported-catalyst CuO/AC with reduced cost exhibited significantly enhanced activity for degrading HORW (5.0 g CuO-5%/AC, 90 mg/L O₃, and 7.3 pH). TEM analysis showed that the high activity of supported-catalyst CuO-5%/AC might be ascribed to the fact that CuO particles were small and highly dispersed on AC. Mass spectrum spectrometry (MS) analysis revealed that the organic components in HORW were first degraded to small molecule oxidation products, which were then oxidized or mineralized further. The influence of CuO loading, CuO/AC dose, ozone dose and initial pH on the degradation efficiency was also investigated. The results of the present work showed that CuO/AC could be a promising supported-catalyst for catalyzing ozonation degradation of HORW.

A multi-site approach to investigate the role of toxicity and confounding factors on plant bioassay results

Development of organisms that live on contaminated soils depends on toxicity as well as several physical and chemical soil properties. We aimed to identify plant bioassays most responsive to contaminants and not to confounding factors due to soil type differences. We implemented a multi-site approach in seven contaminated sites and used different ordinary plant bioassays (fourteen-day-shoot biomass and five-day-root and shoot elongation). Most of the sites were contaminated with polycyclic aromatic hydrocarbons (PAHs), and soils were sampled from areas of both high and low contamination. Bioassays were performed on ninety soil samples and were carried out with six model species. We performed analyses of regulatory PAHs and their derivatives content in the samples. Fourteen-day-shoot biomass responses depended on the site's origin, with an intricate response of plants that faced contrasted soil pH and organic matter content and various contaminant levels. Five-day-shoot and root lengths were informative when considering the most heavily PAH-contaminated site, since both measures exhibited a close dose-dependent response to PAHs but not to soil pH or organic matter content. For the other sites, elongation tests revealed tenuous effects somehow related to the presence of PAHs or their derivatives. We propose that tests based on plant development during their autotrophic phase (the fourteen-day-shoot biomass test in this study) are likely more sensitive to environmental stressors but less specific for contaminant-induced effects. Comparatively, tests based on early and heterotrophic plant development could be particularly more specific for soil contaminants, but the associated responses may be of low sensitivity.

Acute toxicity of water and aqueous extract of soils from Champotón river in Lactuca sativa L

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Inhibitory effect on elongation for radicle and stem of Lactuca sativa was detected.

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Champotón river water showed more phytotoxic effect than aqueous extracts of the soil.

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Radicula and stem of lettuces showed variations in growth when exposed to different water dilutions from Champoton river.

The seeds germination, stem and root elongation of water lettuces (Lactuca sativa L) were used to evaluate the phytotoxicity of water and soil of Champotón River, Campeche, Mexico. water and soil sample were collected from two sampling sites. Lettuce seeds were exposed to three different dilutions of water and aqueous extract of soil. Significant differences on germination, root and stem elongation of lettuce were detected. Water showed more phytotoxic effect than aqueous extract of soil and inhibitory concentration 50 (IC₅₀) for radicle exposed to river water was 52% while stem elongation was 69%. Due to paucity the previously available phytotoxicological studies onto Champotón River, it is now essential to allocate time and resources to consider development of suitable chronic phytotoxicity tests.

Rapid in situ toxicity testing with luminescent bacteria Photorhabdus luminescens and Vibrio fischeri adapted to a small portable luminometer

The present study demonstrates development of a rapid testing protocol based on a small portable luminometer using flash kinetic assessment of bacterial bioluminescence. The laboratory comparisons based on six model organic toxicants and two metals showed significant correlations between responses of freshwater bacteria Photorhabdus luminescens and standard marine bacterial species Vibrio fisheri. While P. luminescens was less sensitive in standard arrangements, the responses of both organisms were comparable in the newly introduced portable luminometer setup. The applicability and reproducibility of the portable luminometer protocol was further demonstrated in the assessment of 43 European wastewater effluents that were simultaneously tested for toxicity and analysed for 150 organic and 20 inorganic contaminants grouped into 13 major chemical classes. Clear association between the toxic responses in both compared bacterial species and the elevated levels of inorganic compounds (toxic metals), chlorophenols and benzotriazole anticorrosives was observed. The new protocol with a portable luminometer provides a fast (30 s) response and may be used as a tool for rapid in situ toxicity evaluation of freshwater environmental samples such as effluents.

Impact of Veterinary Pharmaceuticals on the Agricultural Environment: A Re-inspection

The use of veterinary pharmaceuticals (VPs) is a result of growing animal production. Manure, a great crop fertilizer, contains a significant amount of VPs. The investigation of VPs in manure is prevalent, because of the potential risk for environmental organisms, as well as human health. A re-evaluation of the impact of veterinary pharmaceuticals on the agricultural environment is needed, even though several publications appear every year. The aim of this review was to collate the data from fields investigated for the presence of VPs as an inevitable component of manure. Data on VP concentrations in manure, soils, groundwater and plants were collected from the literature. All of this was connected with biotic and abiotic degradation, leaching and plant uptake. The data showed that the sorption of VPs into soil particles is a process which decreases the negative impact of VPs on the microbial community, the pollution of groundwater, and plant uptake. What was evident was that most of the data came from experiments conducted under conditions different from those in the environment, resulting in an overestimation of data (especially in the case of leaching). The general conclusion is that the application of manure on crop fields leads to a negligible risk for plants, bacteria, and finally humans, but in future every group of compounds needs to be investigated separately, because of the high divergence of properties.

Environmental hazard assessment of contaminated soils in Antarctica: Using a structured tier 1 approach to inform decision-making

Generally, Antarctica is considered to be an untouched area of the planet; however, the region's ecosystems have been subject to increased human pressure for at least the past half-century. This study assessed soils of Fildes Peninsula, where trace element pollution is thought to prevail. Four soil samples were collected from different locations and assessed following tier 1 methodologies for chemical and ecotoxicological lines of evidence (LoE) used in typical soil Environmental Risk Assessment (ERA). Trace element quantification was run on soil samples and sequential extracts, and elutriates were used to address their ecotoxicity using a standard ecotoxicological battery. The highest levels of trace elements were found for Cr, Cu, Ni and Zn, which were well above baseline levels in two sites located near previously identified contamination sources. Trace element concentrations in soils were compared with soil quality guidelines to estimate the contribution of the chemical LoE for integrated risk calculations; risk was found high, above 0.5 for all samples. Total concentrations in soil were consistent with corresponding sequentially extracted percentages, with Cu and Zn being the most bioavailable elements. Bacteria did not respond consistently to the elutriate samples and cladocerans did not respond at all. In contrast, the growth of microalgae and macrophytes was significantly impaired by elutriates of all soil samples, consistently to estimated trace element concentrations in the elutriate matrix. These results translated into lower risk values for the ecotoxicological compared to the chemical LoE. Nevertheless, integrated risk calculations generated either an immediate recommendation for further analysis to better understand the hazardous potential of the tested soils or showed that the soils could not adequately sustain natural ecosystem functions. This study suggests that the soil ecosystem in Fildes has been inadequately protected and supports previous claims on the need to reinforce protection measures and remediation activities.

Effects of oxidative stress reaction for the Eisenia fetida with exposure in Cd2

Earthworms are widely used in all kinds of pollutants as sensitive bio-indicator organisms because of their immediately oxidative stress response under the stress of heavy metal. However, there are a large number of indexes associated with the oxidative stress response. Finding out the key monitoring indexes in the stress process becomes a practical demand of the pollution monitoring and warning process. We studied two groups, the short-term test and the long-term test. The former one is for 10 days, taking out an earthworm every day. The latter test lasted 30 days, taking out an earthworm every 10 days. The Cd²⁺ concentration was set at 50, 100, 125, 250, and 500 mg kg^-1. Post-clitellum segments of earthworms were chosen to determine superoxide enzyme (SOD), peroxidase (POD), glutathione peroxidase (GSH-Px), glutathione-S transferase (GST), catalase (CAT), vitamin E (VE), malondialdehyde (MDA), and acetylcholinesterase (AChE). The results showed that the main bio-indicators associating with oxidative stress reaction in short-term group were CAT, SOD, and POD. MDA could be used as a bio-indicator in the early and mid-term. VE was only the bio-indicator in the mid-term stress. While with the long-term test, the main bio-indicators associated with oxidative stress reaction were GSH-Px and MDA. The AChE activity was only suitable for oxidative stress response caused by heavy metal stress more than 30 days.

Toxicity assessment of diesel- and metal-contaminated soils through elutriate and solid phase assays with the slime mold Dictyostelium discoideum

A suite of organisms from different taxonomical and ecological positions is needed to assess environmentally relevant soil toxicity. A new bioassay based on Dictyostelium is presented that is aimed at integrating slime molds into such a testing framework. Toxicity tests on elutriates and the solid phase developmental cycle assay were successfully applied to a soil spiked with a mixture of Zn, Cd, and diesel fuel freshly prepared (recently contaminated) and after 2 yr of aging. The elutriates of both soils provoked toxic effects, but toxicity was markedly lower in the aged soil. In the D. discoideum developmental cycle assay, both soils affected amoeba viability and aggregation, with fewer multicellular units, smaller fruiting bodies and, overall, inhibition of fruiting body formation. This assay is quick and requires small amounts of test soil, which might facilitate its incorporation into a multispecies multiple-endpoint toxicity bioassay battery suitable for environmental risk assessment in soils. Environ Toxicol Chem 2016;35:1413-1421. © 2015 SETAC.