Sediment Toxicity Tests Research Articles

Comparisons Between Laboratory Sediment Toxicity Test Results and Assessment of Benthic Community Changes for a Lake with Mild Metal Contamination.

Effects of moderate-to-severe sediment contamination may be readily discernable in both sediment toxicity bioassays and benthic community assessments. However, the impact may be less obvious under conditions of relatively mild contamination and significant variation of natural environmental variables. This study evaluated sediment toxicity and benthic community impacts for a shallow eutrophic lake system with relatively low levels of sediment metal contamination. We evaluated selected sediment physical and chemical properties, as well as benthic community structure, for 50 sites along a sediment Pb contamination gradient in the lake. We tested the toxicity of sediment from 20 of the sites, using a standardized 42-days sediment bioassay with Hyalella azteca survival, reproduction, and growth endpoints. Using principal component and correlation analyses we found negative relationships for both Pb and Cu, between sediment metal concentrations and the diversity and abundance of benthic macroinvertebrates. Taxa known to be metal-sensitive (e.g., Hyalella sp. and Physa sp.) were less abundant at sites with relatively higher Pb and Cu concentrations. However, amphipod performance in the chronic toxicity test was not related to sediment Pb or Cu concentrations (but was influenced by sediment organic content). Our results demonstrate that an assessment of community-level effects may be warranted even when sediment metal concentrations are too low to elicit detectable toxic effects in standardized laboratory tests.

Response of a nematode community to the fungicide fludioxonil in sediments of outdoor freshwater microcosms compared to a single species toxicity test

When entering aquatic ecosystems, hydrophobic organic chemicals like the fungicide fludioxonil partition to the sediment compartment where they pose potential risks to benthic invertebrates. To assess the ecological risk for sediment-dwelling invertebrates, nematodes are a suitable organism group, as they are abundantly present and possess key positions in the benthic food web. Therefore, the toxicity of the fungicide fludioxonil to nematodes was assessed in a standardized sediment toxicity test with Caenorhabditis elegans (ISO 10872), as well as in an outdoor sediment-spiked microcosm test system. In the microcosms, effects on the nematode species composition were studied, while exposure concentrations of fludioxonil were monitored in total sediment and pore water. Toxic effects on nematodes were better predicted using concentrations in pore water than total sediment concentrations. In laboratory single species tests, fludioxonil showed considerably lower toxicity in spiked field-collected sediment, compared to artificial ISO-sediments. Applying an assessment factor of 10 to the C. elegans 96-h EC10, a Tier-1 RACNematode of 7.99 mg kg−1 dry artificial sediment (corresponding to 69 μg l−1 in pore water) appeared to be protective for nematode communities in microcosms that showed no response in total abundance and species composition up to 39.9 mg fludioxonil kg−1 dry sediment (corresponding to 392 μg l−1 in pore water).

Effect of calcite saturation state on the growth and mortality of Heterocypris incongruens and a proposal for an reference artificial sediment in the sediment toxicity test ISO14371

Since the establishment of the whole-contact sediment toxicity test using Heterocypris incongruens in 2012, this user-friendly method has been widely used for the assessment of many kinds of solid samples, such as sediment, soil, compost, and sewage sludge. There are two endpoints for this method: mortality and growth inhibition. Currently, there is no standard toxicity threshold established for the endpoint of growth inhibition. However, there is evidence showing that the calcite saturation state of the overlying water, which might be different among various samples, influences the growth and survival of H. incongruens. Thus, it is necessary to characterize the influence of the calcite saturation state to ensure that the test results are reliable and comparable among different samples. In the present study, we created artificial sediments comprised of quartz sand and 0–20% calcite particulates to manipulate the calcite saturation state in the overlying water and performed the test using H. incongruens for 6 d. The results show that a low calcite saturation state inhibited the growth of H. incongruens but had no effect on survival rate. The growth of ostracods was linearly related to the calcite saturation index of the overlying water. Additionally, a formula for artificial sediment consisting of 10% calcite and 90% quartz sand for the H. incongruens toxicity test was proposed. This study helps to distinguish H. incongruens growth inhibition caused by calcite saturation from that caused by toxicity.

Grandidierella lignorum (Amphipoda: Aoridae) can be used for assessing the toxicity of sediment with varying grain sizes and low organic content

Sediment grain size and organic matter influences the distribution of macrozoobenthic fauna. These parameters also influence bioavailability and toxicity of contaminants in aquatic systems, because sediment is the sink and source for most contaminants. These sediment parameters therefore potentially confound sediment toxicity results when using inappropriate toxicity test organisms and/or test conditions. Grandidierella lignorum is being developed as a sediment toxicity test organism for South African coastal waters and it is crucial that its preference for sediment grain size and organic matter is determined with the aim of defining test conditions for sediment toxicity tests. G. lignorum were offered a choice of six sediment grades and two types of organic matter of varying concentrations (0–8%) to determine their preference thereof. Very coarse sediment grade and mud were consistently the least selected particle sizes in all experiments. Sediment with low organic matter (<0.5%), was also consistently selected by G. lignorum and this was not influenced by sediment particle size. G. lignorum can therefore be used for the toxicity testing of sediment with a wide grain size variation, although results may be confounded in sediment samples largely comprised of very coarse or muddy sediment.

Pollution induced change of liver of Oreochromis niloticus: metals accumulation and histopathological response

The present study, pointed to assess heavy metal accumulation like Aluminum (Al), Cadmium (Cd), Chrome (Cr), Cobalt(Co), Copper(Cu), Iron(Fe), Lead (Pb), Manganese(Mn), Nickel(Ni), Selenium(Se) and Zinc(Zn) in water, sediments and liver of Oreochromis niloticus, which collected from sewage water in El-kharja, New Valley, Egypt using inductively coupled plasma mass spectrometry (ICP-MS). Also, the histopathological changes of liver of Oreochromis niloticus were reported. These histopathological changes were detected using different staining types as a pollution biomarker. Iron showed the highest accumulation level in water (9.06±0.86 ppm), sediments (175.1±20.8 ppm) and liver (158.17±38.59 ppm), followed by Al> Mn> Ni> Zn> Pb> Cr> Se> Cu> Co> Cd. However, these elements showed Fe> Al> Ni> Mn> Cr> Cu> Zn> Pb> Cd> Se> Co accumulation trend in sediments. In liver these metals showed Fe> Se>Al> Zn>Mn> Cu>Ni> Cr> Pb> Co> Cd trend. Histopathological examination of fish liver showed signs of progressive alterations such as disorganization of architecture of liver cells, hydropic degeneration and vacuolation of hepatocytes. Also, dilation and congestion in blood sinusoids, hypertrophic and increase in number of küpffer cells were chronicled. Sever deposition of hemosiderin pigments were reported while necrosis with pyknotic nucleus and focal histopathological characters were observed side by side with normal cell. Our results concluded that water, sediment and liver accumulation toxicity tests and histopathological changes of liver may be associated, and these approaches may be used together to describe the environmental state and water quality assessment.

Single and joint oxidative stress–related toxicity of sediment-associated cadmium and lead on Bellamya aeruginosa

The biotoxicity of heavy metals in sediments toward benthic organisms has evoked great concern for the health of freshwater ecosystems. This study applied a sediment toxicity testing protocol to investigate the single and joint toxicity of cadmium (Cd) and lead (Pb) on Bellamya aeruginosa. B. aeruginosa were exposed to different concentrations of Cd (5, 25, and 100 mg/kg), Pb (20, 100, and 400 mg/kg), and their different concentration combinations. A suite of biomarkers, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), metallothionein (MT), malondialdehyde (MDA), and acetylcholinesterase (AChE), were measured after 7, 14, 21, and 28 days of exposure to evaluate their oxidative stress status. Cell apoptosis of soft tissue was also determined after exposure. Results revealed that these endpoints represented sensitive biomarkers for the characterization of the oxidative stress response induced by these metals. Specifically, a decrease of SOD and GPx and an increase of MDA were indicative of the potential failure of the antioxidant defense system in neutralizing the reactive oxygen species (ROS) generated in the exposure of the Pb-treated group. The integrated biomarker response (IBR) index revealed the most significant sub-lethal toxicity for Pb-spiked sediments, leading to the highest rate of cell apoptosis (70.8%). Exposure to Cd resulted in a time- and dose-dependent effect on MT levels, which suggested active detoxification of this metal. Exposure to the mixture resulted in amelioration of Pb toxicity, likely due to the competitive binding of Cd to active enzyme, with the result of an observed antagonistic interaction. This study indicated that B. aeruginosa represents a good biomonitor for assessing Cd and Pb contamination of sediments, and laid the foundation for their potential risk assessments in freshwater ecosystems.

Assessment of Potentially Toxic Elements in Technosols by Tailings Derived from Pb–Zn–Ag Mining Activities at San Quintín (Ciudad Real, Spain): Some Insights into the Importance of Integral Studies to Evaluate Metal Contamination Pollution Hazards

This work presents an integral methodological approach to assess the environmental potential hazards posed by metals and metalloids hosted by spolic technosols derived from old tailings from a mining operation for galena (PbS, with high Ag contents)-sphalerite (ZnS, with a varied cohort of trace elements contents) in central Spain. We studied the total and soluble concentrations and spatial distribution of Pb, Zn, Cd, As, and Fe and the mineralogy of these soils, as well as an ecotoxicological evaluation by means of bioassays. The indices assessing soil contamination such as pollution load index (PI) and natural mobility index (NMI) have been calculated. Furthermore, the phytotoxic effect of the soil samples has been determined and a chronic sediment toxicity test using the benthic ostracod Heterocypris incongruens was applied. The geochemical study of 33 spolic technosols samples indicates large to extremely large metal and metalloid total contents: up to 48,600 mg kg−1 Pb, 34,000 mg kg−1 Zn, 500 mg kg−1 Cd, and 1000 mg kg−1 As. Given that sphalerite is usually the most important host mineral for cadmium in hydrothermal mineral deposits, there is a high correlation (R = 0.75) between this element and Zn. On the other hand, despite being two metallogenically intertwined elements in ore deposits, Pb and Zn show a less significant relationship, which can be attributed both to heterogeneities in the mineralogical composition of the veins, and to the complex history of the mineral concentration process: In the older process, the interest was only for Pb, meanwhile in the late period, the interest was focused in Zn. The Phytotoxkit® bioassay showed that soils with high PTEs presented very high toxicity, particularly the inhibition germination is related to Pb, As, and Cd content and root inhibition with Pb content. Both indexes were correlated with pH and electrical conductivity; samples with lower pH and higher soluble salt content are those with higher seed germination inhibition and root growth inhibition. On the other hand, the Ostracodtoxkit® bioassay showed very high sensitivity, with 100% mortality. The applied bioassays confirmed the soil toxicity and it is highly recommended to complement the results from environmental chemistry with results from bioassays, in order to provide a more complete and relevant information on the bioavailability of contaminants and to characterize the risk of contaminated areas.

Insights into the sediment toxicity of personal care products to freshwater oligochaete worms using Fourier transform infrared spectroscopy

Personal care products (PCPs) are ubiquitous in the environment due to their wide use in daily life. However, there are insufficient sediment toxicity data of PCPs under ecologically relevant conditions. Here we used Fourier transform infrared spectroscopy (FTIR) to investigate the sediment toxicity of triclosan (TCS) and galaxolide (HHCB) to two freshwater benthic macroinvertebrates, Limnodrilus hoffmeisteri and Branchiura sowerbyi, in microcosms containing a diverse biological community. Exposure to 8 µg TCS/g and 100 µg HHCB/g dry weight (dw) sediment induced significant biochemical alterations in the L. hoffmeisteri tissue. 8 µg TCS/g primarily affected proteins and nucleic acid while 100 µg HHCB/g mainly affected proteins and lipids of L. hoffmeisteri. However, 0.8 µg TCS/g and 30 µg HHCB/g did not cause significant subcellular toxicity to L. hoffmeisteri. In contrast, exposure of B. sowerbyi to 30 µg HHCB/g led to significant biochemical changes, including proteins, polysaccharides and lipids. Therefore, B. sowerbyi was more sensitive to sediment-associated HHCB than L. hoffmeisteri. Such effects were significantly enhanced when the HHCB concentration increased to 100 µg/g dw where death of B. sowerbyi occurred. These results demonstrate the application of FTIR spectroscopy to sediment toxicity testing of chemicals to benthic invertebrates with biochemical alterations as endpoints that are more sensitive than standard toxic endpoints (e.g., survival and growth).

Preparation of Cu2+ and Pb2+ spiked sediment for sediment toxicity tests: a case study from Soai Rap estuary in Sai Gon - Dong Nai river system

Heavy metals contamination in river sediment is becoming more severe, as is also the case in Soai Rap estuary, Vietnam, where Cu and Pb polution is significant. The evironmental risks posed by heavy metals are usually assessed by toxicity tests using sediment spiked with contaminants in different concentrations. In order to recreate natural conditions, the preparation of sediment samples spiked with heave metals must be carried out following strict procedures. The objective of the study is therefore to determine the adsorption kinetic and equilibrium parameters of two heavy metals (Cu2+ and Pb2+) on surface sediment collected from an intertidal mudflat in the Soai Rap estuary of Vietnam. The experiments were conducted with a liquid (Cu2+ and Pb2+ solutions) to solid (sediment) ratio of approximately 1:10. Elutriates were prepared by shaking the spiked sediment sample in artificial seawater at a ratio of 1:4 (wet sediment/water). The Cu2+ solution reached equilibrium after about 12 hours and the maximum adsorption capacity of 0.86 mg/g while the Pb2+ solution reached equilibrium after 10 hours, with the maximum adsorption capacity of 35.2 mg/g. The regression analysisof experimental data of Cu2+ and Pb2+ adsorption on sediment has shown good consistency with both Langmuir and Freundlich models, whereas the Langmuir model was found to be more appropriate. The adsorption kinetic of both heavy metals was well described by the pseudo second-order adsorption kinetic model and the desorption processes were characterised using the Langmuir and Freundlich models (both models were suitable for Cu2+ desorption but only Freundlich for Pb2+). Using the present methodology, the concentrations of heavy metals spiked on sediment could be calculated, however the maximum adsorption capacity for both substances was not yet achieved. Further findings include the determination of the equilibrium time for adsorption, very relevant when spiking sediments for toxicity tests to evaluate the environmental risks of polution with heavy metals in the Soai Rap estuary, Vietnam.&#x0D; Ô nhiễm kim loại nặng trong trầm tích cửa sông ngày càng trầm trọng, như trường hợp ở cửa sông Soài Rạp, Việt Nam, nơi mà ô nhiễm Cu, Pb là đáng kể. Rủi ro môi trường do kim loại nặng gây ra thường được đánh giá bằng các thử nghiệm độc tính sử dụng trầm tích kết hợp với các chất gây ô nhiễm ở các nồng độ khác nhau. Để tái tạo các điều kiện tự nhiên, việc chuẩn bị các mẫu trầm tích kết hợp với kim loại nặng phải được thực hiện theo những quy trình nghiêm ngặt. Do đó, mục tiêu của nghiên cứu là xác định các thông số động học và cân bằng hấp phụ của hai kim loại nặng (Cu2+ và Pb2+) lên trầm tích mặt được thu thập từ một bãi bồi tại cửa sông Soài Rạp, Việt Nam. Các thí nghiệm được thực hiện với tỷ lệ chất lỏng (dung dịch Cu2+ và Pb2+) và chất rắn (trầm tích) xấp xỉ 1:10. Dung dịch rửa giải được chuẩn bị bằng cách lắc mẫu trầm tích đã kết hợp trong nước biển nhân tạo theo tỷ lệ 1: 4 (trầm tích ướt/nước). Dung dịch Cu2+ đạt trạng thái cân bằng sau khoảng 12 giờ và dung lượng hấp phụ tối đa 0,86 mg/g trong khi dung dịch Pb2+ đạt trạng thái cân bằng sau 10 giờ, với dung lượng hấp phụ tối đa 35,2 mg/g. Phân tích hồi quy dữ liệu thực nghiệm của quá trình hấp phụ Cu2+ và Pb2+ lên trầm tích đã cho thấy phù hợp với cả hai mô hình Langmuir và Freundlich, nhưng mô hình Langmuir được tìm thấy là phù hợp hơn. Động học hấp phụ của cả hai kim loại nặng được mô tả là phù hợp với mô hình động học hấp phụ bậc hai giả và các quá trình giải hấp được đặc trưng bằng mô hình Langmuir và Freundlich (cả hai mô hình đều phù hợp với giải hấp Cu2+ nhưng chỉ Freundlich cho Pb2+). Sử dụng phương pháp hiện tại, nồng độ kim loại nặng kết hợp lên trầm tích có thể được tính toán, tuy nhiên khả năng hấp phụ tối đa của cả hai chất vẫn chưa đạt được. Hơn nữa, việc xác định thời gian cân bằng cho hấp phụ, rất phù hợp khi sử dụng trầm tích kết hợp cho thử nghiệm độc tính để đánh giá rủi ro môi trường ô nhiễm kim loại nặng ở cửa sông Soài Rạp, Việt Nam.

Development of an acute sediment toxicity test using an endemic benthic macroinvertebrate, Chironomus species to assess the toxicity of Philippines’ Pasig River sediments

In the absence of a sediment quality guideline, mere characterization regarding the identity and levels of the constituents present in sediments, will not contribute much to an effort of establishing the impact of sediment quality to the aquatic environment. Available standard methods for sediment toxicity tests require the use of species that may not be accustomed to a tropical climate such as in the Philippines. In this regard, area of this study was to assess toxicity of the sediment from Pasig River through the use of an endemic midge (order Diptera, family Chironomidae) collected from Los Baños, Laguna, Philippines as test species. Pasig River is one of the most important waterways in the Philippines, traversing six major cities of Metro Manila. Such strategic location of the River, also explains why it is heavily impacted by both point and nonpoint sources of toxicants. Sediment samples were collected in April 2007, month of dry season and November 2007, month of wet season at five sampling stations along the Pasig River—Delpan, Nagtahan, Pandacan, Guadalupe, and Bambang. A modified 96-hour acute toxicity test was adopted in this study in which sediment samples were mixed with “control” sediment, also obtained locally and subsequently and exposed to the test species. Results suggested that the most polluted and most toxic was the Delpan station which yielded the lowest LC50. The LC50 was experimentally determined via probit analysis. Moreover, it was determined that sediment samples collected during the dry season exhibited lower toxicity towards these organisms than those samples collected during the wet season possibly due the effect of runoff. In view of the results obtained, the locally developed ecotoxicological assay performed on sediments of Pasig River can be used to assess and to distinguish sites along Pasig River that could be potentially toxic based upon its response to the locally grown Chironomids species.

Evaluation of potential confounding factors in sediment toxicity tests with Hyalella azteca (Saussure, 1858)

Ecotoxicological tests performed in waters with low salinities, typical of estuarine environments, are limited regarding the availability of test organisms. The amphipod Hyalella azteca , an organism protocoled for trials with freshwater sediments, presents a potential for use in saltwater tests in which the confounding factors, such as salinity and sediment grain size, should be evaluated to avoid errors in the results in relation to the sensitivity of the organism. Thus, amphipod cultivations in salinities of 0, 5, 10 and 20 were conducted, to perform tests of tolerance to salinity, and sensitivity to a reference toxicant. The tolerance of the species to different sediment grain sizes and organic matter contents was evaluated in tests with reconstituted sediments in five different compositions, varying the content of organic matter (5 to 20%), clay and sand (0 to 95%). The results of the cultivations showed that animals maintained present the best reproduction and survival rates at salinity 5, and a tolerance limit under chronic conditions, at salinity above 10. The salinity can be considered a confounding factor since the tests carried out with the reference toxicant showed the higher resistance of the species under conditions of higher salinities. The species present tolerance to different sediment grain sizes and organic matter contents; therefore, this factor does not interfere in the survival of H. azteca during the ecotoxicological tests.

Bioaccumulation and toxicity of uranium, arsenic, and nickel to juvenile and adult Hyalella azteca in spiked sediment bioassays.

Uranium (U) mining and milling release arsenic (As), nickel (Ni) and U to receiving waters, which accumulate in sediments. The objective of the present study was to investigate if As, Ni, and U concentrations in tissue residue of Hyalella azteca, overlying water, sediment porewater, and solids could predict juvenile and adult survival and growth in conditions similar to lake sediments downstream of U mines and mills. We conducted 14-d static sediment toxicity tests spiked with U, As, and Ni salts. For U, we spiked uranyl nitrate with sodium bicarbonate to limit U precipitation once in contact with circumneutral sediment. The median lethal concentrations for As, Ni, and U of juveniles and adults based on measured concentrations in sediments were 134 and 165 μg/g, 370 and 787 μg/g, and 48 and 214 μg/g, respectively. Adult survival and growth linearly decreased with increasing bioaccumulation. For juveniles, metal accumulation linearly predicted survival. We calculated median lethal body concentrations for juveniles and adults of 5 and 36 μg As/g, 14 and 49 μg Ni/g, and 0.4 and 1.0 μg U/g. The concentrations of As, Ni, and U in tissue residue leading to a 20% decrease in adult growth were 32 μg As/g, 44 μg Ni/g, and 1 μg U/g. Overall, the present study showed that U was the most toxic element, followed by As and Ni; that juveniles were more sensitive to the 3 metals tested than adults; and that threshold body concentrations can support assessment of benthic invertebrate community impairment. Environ Toxicol Chem 2018;37:2340-2349. © 2018 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals, Inc. on behalf of SETAC.

Sediment quality assessment of the tributaries of the Santos-São Vicente Estuarine System – Brazil

The Santos-São Vicente Estuarine System has a long history of environmental impacts, and several studies have been performed in this region. However, the quality of its tributaries was not previously studied. This study aimed to investigate the quality of sediments from five rivers (Santana, Mariana, Piaçabuçu, Quilombo, and Diana Rivers) and three sampling sites at Piaçaguera Canal (riverbed, right and left banks), by using an integrated approach involving chemical analyses and whole sediment toxicity tests. Chronic and acute toxicity tests were performed using, respectively, copepods Nitocra sp. and amphipods Tiburonella viscana. The studied sediments presented moderate to high levels of PAHs, PCBs, metals (Cu, Hg, Ni, Pb, Zn), and As. The majority of sediments produced chronic toxic effects, and samples from Piaçaguera Canal were consistently toxic in all acute and chronic tests. The integration of data through multivariate analyses indicated that the toxicity was closely related to the sediments contamination. Chemical data were compared with sediment quality guidelines, which evidenced that the site-specific values are adequate to predict impacts. The levels of organic chemicals and metals suggest constant inputs from diffuse and point sources, demanding actions to ensure effective control and management of the contamination sources to the estuary.

The Toxicogenome of Hyalella azteca: A Model for Sediment Ecotoxicology and Evolutionary Toxicology.

Hyalella azteca is a cryptic species complex of epibenthic amphipods of interest to ecotoxicology and evolutionary biology. It is the primary crustacean used in North America for sediment toxicity testing and an emerging model for molecular ecotoxicology. To provide molecular resources for sediment quality assessments and evolutionary studies, we sequenced, assembled, and annotated the genome of the H. azteca U.S. Lab Strain. The genome quality and completeness is comparable with other ecotoxicological model species. Through targeted investigation and use of gene expression data sets of H. azteca exposed to pesticides, metals, and other emerging contaminants, we annotated and characterized the major gene families involved in sequestration, detoxification, oxidative stress, and toxicant response. Our results revealed gene loss related to light sensing, but a large expansion in chemoreceptors, likely underlying sensory shifts necessary in their low light habitats. Gene family expansions were also noted for cytochrome P450 genes, cuticle proteins, ion transporters, and include recent gene duplications in the metal sequestration protein, metallothionein. Mapping of differentially expressed transcripts to the genome significantly increased the ability to functionally annotate toxicant responsive genes. The H. azteca genome will greatly facilitate development of genomic tools for environmental assessments and promote an understanding of how evolution shapes toxicological pathways with implications for environmental and human health.

Sensitive community responses of microbiota to copper in sediment toxicity test.

Sediment contamination is widespread and can be toxic to aquatic ecosystems and impair human health. Despite their significant ecological function, meio- and microbiota in aquatic ecosystems have been poorly studied in conventional sediment ecotoxicity tests because of the difficulty in sample collecting and identification. In the present study, a novel DNA metabarcoding method was used to assess the effects of spiked copper (Cu) on benthic eukaryotic and prokaryotic communities in laboratory sediment toxicity tests with macroinvertebrates, the chironomid Chironomus tepperi and the amphipod Austrochiltonia subtenuis. In addition to the obvious toxic effects to experimental animals, microbiota (bacteria, protists, algae, and fungi) were significantly altered by spiked Cu in the sediments. The phylogenetic diversity of eukaryotic communities was decreased after spiked-Cu exposure. Even a low-spiked Cu treatment (125 mg/kg) altered structures of eukaryotic and prokaryotic communities in the amphipod experiment. The present study demonstrates that measuring microbiota communities will expand our understanding of the influences of contaminants on aquatic ecosystems. Particularly, the alterations of phylogenetic biodiversity of eukaryotic communities and the structure of sedimentary communities are sensitive indicators for sediment contamination, which can be incorporated in the monitoring and assessment of sediment quality. Environ Toxicol Chem 2018;37:599-608. © 2017 SETAC.

Towards more ecological relevance in sediment toxicity testing with fish: Evaluation of multiple bioassays with embryos of the benthic weatherfish (Misgurnus fossilis)

The effects of sediment contamination on fish are of high significance for the protection of ecosystems, human health and economy. However, standardized sediment bioassays with benthic fish species, that mimic bioavailability of potentially toxic compounds and comply with the requirements of alternative test methods, are still scarce. In order to address this issue, embryos of the benthic European weatherfish (Misgurnus fossilis) were exposed to freeze-dried sediment (via sediment contact assays (SCA)) and sediment extracts (via acute fish embryo toxicity tests) varying in contamination level. The extracts were gained by accelerated solvent extraction with (i) acetone and (ii) pressurized hot water (PHWE) and subsequently analyzed for polycyclic aromatic hydrocarbons, polychlorinated biphenyls and polychlorinated dibenzodioxins and dibenzofurans. Furthermore, embryos of the predominately used zebrafish (Danio rerio) were exposed to extracts from the two most contaminated sediments. Results indicated sufficient robustness of weatherfish embryos towards varying test conditions and sensitivity towards relevant sediment-bound compounds. Furthermore, a compliance of effect concentrations derived from weatherfish embryos exposed to sediment extracts (96h-LC50) with both measured gradient of sediment contamination and previously published results was observed. In comparison to zebrafish, weatherfish embryos showed higher sensitivity to the bioavailability-mimicking extracts from PHWE but lower sensitivity to extracts gained with acetone. SCAs conducted with weatherfish embryos revealed practical difficulties that prevented an implementation with three of four sediments tested. In summary, an application of weatherfish embryos, using bioassays with sediment extracts from PHWE might increase the ecological relevance of sediment toxicity testing: it allows investigations using benthic and temperate fish species considering both bioavailable contaminants and animal welfare concerns.

Assessing measurable adverse changes to benthic invertebrate communities based on site-specific sediment toxicity testing and community data at the Anniston, Alabama PCB site

ABSTRACTLaboratory toxicity tests were conducted for polychlorinated biphenyl (PCB)-containing sediment from Choccolocco Creek at the Anniston PCB Site. The objective of this investigation was to develop a site-specific PCB concentration–response relationship for invertebrate test organisms. Test results from reference locations were used to develop background-adjusted 10% (EC10*) and 20% (EC20*) effect concentrations for a range of survival, growth, and reproduction endpoints. The EC20* values ranged from 4.43 to 114 milligrams of PCBs per kilogram (mg/kg) of sediment on a dry weight basis for reproductive endpoints, 28 to 67.7 mg/kg sediment for growth, and 123 to 165 mg/kg sediment for survival. The aggregate EC20* response range for endpoints that demonstrated good test performance with reasonable ranges in control variability (<20%) and reference sample responses was 14.3 to 165 mg/kg. The PCB concentrations in sediments for a majority of the Site rarely exceed even the lowest of these thresholds. Given the protective process used to develop these thresholds, there is a high level of confidence that benthic communities are not impacted. This finding is supported by direct measurements of the benthic communities that have been living and reproducing on the Site.

Duration of life-cycle toxicity tests with the ostracod Heterocypris incongruens.

An acute sediment toxicity test using the ostracod Heterocypris incongruens is user friendly and has high sensitivity; however, a life-cycle test using this species has not been developed. The most challenging problem when developing a life-cycle test is that the egg development time varies greatly and is sometimes too long (> 150 d) to monitor. It is desirable to shorten the duration of life-cycle toxicity tests including the observation period of egg development while preserving the ecological relevance of the net reproductive rate (R0 ), an endpoint in the life-cycle test. Therefore, in the present study, we suggest a practical test duration for R0 using population growth rate (λ) as a measure of ecological relevance. We collected a range of life history characteristics of the ostracod by combining data from the literature and experimental results, constructed population matrix models, and calculated λ for 20 life history patterns. The results showed that a longer test period (> 150 d) did not increase the correlation coefficients between R0 and λ. Rather, a shorter test duration resulted in R0 being highly correlated with λ. Our results suggest that a life-cycle toxicity test using the ostracod can provide an ecologically relevant toxicity endpoint, even if the test is abandoned after approximately 50 d and unhatched eggs remain. Environ Toxicol Chem 2017;36:3443-3449. © 2017 SETAC.

Effects-based spatial assessment of contaminated estuarine sediments from Bear Creek, Baltimore Harbor, MD, USA.

Estuarine sediments in regions with prolonged histories of industrial activity are often laden to significant depths with complex contaminant mixtures, including trace metals and persistent organic pollutants. Given the complexity of assessing risks from multi-contaminant exposures, the direct measurement of impacts to biological receptors is central to characterizing contaminated sediment sites. Though biological consequences are less commonly assessed at depth, laboratory-based toxicity testing of subsurface sediments can be used to delineate the scope of contamination at impacted sites. The extent and depth of sediment toxicity in Bear Creek, near Baltimore, Maryland, USA, was delineated using 10-day acute toxicity tests with the estuarine amphipod Leptocheirus plumulosus, and chemical analysis of trace metals and persistent organic pollutants. A gradient of toxicity was demonstrated in surface sediments with 21 of 22 tested sites differing significantly from controls. Effects were most pronounced (100% lethality) at sites proximate to a historic industrial complex. Sediments from eight of nine core samples to depths of 80cm were particularly impacted (i.e., caused significant lethality to L. plumulosus) even in locations overlain with relatively non-toxic surface sediments, supporting a conclusion that toxicity observed at the surface (top 2cm) does not adequately predict toxicity at depth. In seven of nine sites, toxicity of surface sediments differed from toxicity at levels beneath by 28 to 69%, in five instances underestimating toxicity (28 to 69%), and in two instances overestimating toxicity (44 to 56%). Multiple contaminants exceeded sediment quality guidelines and correlated positively with toxic responses within surface sediments (e.g., chromium, nickel, polycyclic aromatic hydrocarbon (PAH), total petroleum hydrocarbon). Use of an antibody-based PAH biosensor revealed that porewater PAH concentrations also increased with depth at most sites. This study informs future management decisions concerning the extent of impact to Bear Creek sediments, and demonstrates the benefits of a spatial approach, relying primarily on toxicity testing to assess sediment quality in a system with complex contaminant mixtures.

Development of a chronic sediment toxicity test using the benthic ostracod Heterocypris incongruens and their application to toxicity assessments of urban road dust

This study reports on the development and application of a chronic sediment toxicity test using the benthic ostracod Heterocypris incongruens. H. incongruens reproduction parameters such as egg production, first day of brooding, egg-laying ratio, and hatching ratio were examined in this study. The test was first validated by determining the repeatability of the test method under seven control performances. The results showed good test repeatability of most endpoints, with coefficient of variation (CV) results below 15%. However, lifetime egg production, hatching ratio, and the reproductive rate were highly variable, with CVs ranging from 29.5% to 51.9%. Next, an application example of the proposed chronic method was performed using a series of urban road dust (URD) samples diluted with a reference sediment and compared to a 6 d H. incongruens toxicity test. The results of the proposed chronic test showed a statistically significant difference in the first day of brooding at 6.25% URD which did not exhibit significant mortality and growth inhibition in 6 d toxicity test.