Evaluation of Sublethal Toxicity of Nitrite to a Suite of Aquatic Organisms in Support of the Derivation of a Chronic Environmental Water Quality Benchmark.

Nitrite is a naturally-occurring inorganic compound that occurs in aquatic environments as an intermediary between nitrate and ammonia in the nitrogen cycle. It is a contaminant of potential concern resulting from anthropogenic activities in some cases. While the acute toxicity of nitrite has been characterized in previous studies, its sublethal toxicity is less understood.

Implications of deep-seabed mining on marine ecosystems-Introduction to a special series of papers.

After more than 50 years of exploration and research that has intensified over the past decade, deep-seabed mining (DSM) remains a controversial subject, resulting mainly from legacy issues of other extractive industries. Moreover, our planet is environmentally challenged, with climate change as one of the major issues that we collectively face. Deep-seabed mining aims to collect metal resources lying on the deep seabed to help meet increased global demand caused by growth in population and urbanization, and clean energy, in a way that reduces pressures on land, such as deforestation and community relocation.

Are current tissue-based selenium guidelines and criteria overly protective of freshwater fish populations? A critical review with recommendations.

Several decades after selenium impacts on wild fish populations were observed in freshwater reservoirs receiving fly ash effluents from electric power facilities at Belews Lake and Hyco Reservoir (North Carolina, USA), developments in selenium (Se) toxicology have led to a greater understanding of Se effects on freshwater fish. These latter advancements have allowed regulatory agencies in several jurisdictions to develop tissue-based toxicity benchmarks for the protection of aquatic life. These benchmarks were generally derived from datasets encompassing multiple fish species and designed to protect the most sensitive species (US Environmental Protection Agency [EPA] water quality criteria).

Lentic, lotic, and sulfate-dependent waterborne selenium screening guidelines for freshwater systems.

There is consensus that fish are the most sensitive aquatic organisms to selenium (Se) and that Se concentrations in fish tissue are the most reliable indicators of potential toxicity. Differences in Se speciation, biological productivity, Se concentration, and parameters that affect Se bioavailability (e.g.

Evaluation of the effect of water type on the toxicity of nitrate to aquatic organisms.

A suite of acute and chronic toxicity tests were conducted to evaluate the sensitivity of freshwater organisms to nitrate (as sodium nitrate). Acute exposures with rainbow trout (Onchorhynchus mykiss) and amphipods (Hyalella azteca), as well as chronic exposures with H. azteca (14-d survival and growth), midges (Chironomus dilutus; 10-d survival and growth), daphnids (Ceriodaphnia dubia; 7-d survival and reproduction), and fathead minnows (Pimephales promelas; 7-d survival and growth) were used to determine sublethal and lethal effect concentrations.

Species sensitivity distribution evaluation for selenium in fish eggs: considerations for development of a Canadian tissue-based guideline.

A freshwater Se guideline was developed for consideration based on concentrations in fish eggs or ovaries, with a focus on Canadian species, following the Canadian Council of Ministers of the Environment protocol for developing guideline values. When sufficient toxicity data are available, the protocol recommends deriving guidelines as the 5th percentile of the species sensitivity distribution (SSD). When toxicity data are limited, the protocol recommends a lowest value approach, where the lowest toxicity threshold is divided by a safety factor (e.

An aquatic toxicological evaluation of sulfate: the case for considering hardness as a modifying factor in setting water quality guidelines.

Elevated concentrations of sulfate occur commonly in anthropogenically impacted and natural waters. However, water quality guidelines (WQG) have not been developed in many jurisdictions, and chronic toxicity data are scarce for this anion. A variety of test organisms, including species of invertebrate, fish, algae, moss, and an amphibian, were tested for chronic toxicity to develop a robust dataset that could be used to develop WQGs.

A new quality assurance system for the evaluation of ecotoxicity studies submitted under the New Substances Notification Regulations in Canada.

New substances destined for import into, or manufacture in, Canada must be reported to Environment Canada and Health Canada under the New Substances Notification Regulations (Chemicals and Polymers) (NSNR). With the use of information provided by the notifier, and other complementary information available to the 2 departments, the New Substances Program conducts ecological and human health risk assessments. Over the past 10 y, more than 750 ecotoxicity studies have been submitted to the New Substances Program of Environment Canada under the NSNR.