Use of Toxicity Identification Evaluation Procedures to Clarify the Relationship Between Ammonium Concentrations and Phytoplankton Blooms in the San Francisco Bay Estuary, California, USA.

Phytoplankton blooms in the northern San Francisco Bay Estuary have historically supported much of the larval fish production in the estuary. In the past, blooms were limited largely by reduced light intensities and net outflows through the system, as well as dense populations of introduced clams that continuously filter the water column. Conversely, the estuary is exposed to a wide variety of contaminants that may also impact phytoplankton growth.

Using ultrahigh-resolution mass spectrometry and toxicity identification techniques to characterize the toxicity of oil sands process-affected water: The case for classical naphthenic acids.

Previous assessments of oil sands process-affected water (OSPW) toxicity were hampered by lack of high-resolution analytical analysis, use of nonstandard toxicity methods, and variability between OSPW samples. We integrated ultrahigh-resolution mass spectrometry with a toxicity identification evaluation (TIE) approach to quantitatively identify the primary cause of acute toxicity of OSPW to rainbow trout (Oncorhynchus mykiss). The initial characterization of OSPW toxicity indicated that toxicity was associated with nonpolar organic compounds, and toxicant(s) were further isolated within a range of discrete methanol fractions that were then subjected to Orbitrap mass spectrometry to evaluate the contribution of naphthenic acid fraction compounds to toxicity.

Application of sediment toxicity identification evaluation techniques to a site with multiple contaminants.

Sediment toxicity identification evaluations (TIEs) are conducted to determine causes of adverse effects observed in whole-sediment toxicity tests. However, in multiple contaminant scenarios, it is problematic to partition contributions of individual contaminants to overall toxicity. Using data from a site with multiple inputs and contaminants of concern, the authors describe a quantitative approach for the TIE process by tracking toxicity units to determine whether all toxicity is accounted for.

A New Toxicity Test Using the Freshwater Copepod Cyclops vernalis.

The cladocerans Ceriodaphnia dubia and Daphnia magna are widely used in environmental toxicity testing and the test methodologies for these species are well developed. However, copepods are a much more abundant contributor to zooplankton in many lakes, but they are not routinely used in toxicity tests. Therefore, we propose toxicity test methods for the freshwater copepod, Cyclops vernalis assessing effects on its survival and growth.

The effect of sulfate on selenate bioaccumulation in two freshwater primary producers: A duckweed (Lemna minor) and a green alga (Pseudokirchneriella subcapitata).

Predicting selenium bioaccumulation is complicated because site-specific conditions, including the ionic composition of water, affect the bioconcentration of inorganic selenium into the food web. Selenium tissue concentrations were measured in Lemna minor and Pseudokirchneriella subcapitata following exposure to selenate and sulfate. Selenium accumulation differed between species, and sulfate reduced selenium uptake in both species, indicating that ionic constituents, in particular sulfate, are important in modifying selenium uptake by primary producers.

Molecular responses to 17β-estradiol in early life stage salmonids.

Environmental estrogens (EE) are ubiquitous in many aquatic environments and biological responses to EEs in early developmental stages of salmonids are poorly understood compared to juvenile and adult stages. Using 17β-estradiol (E2) as a model estrogen, waterborne exposures were conducted on early life stage rainbow trout (Oncorhynchus mykiss; egg, alevin, swim-up fry) and both molecular and physiological endpoints were measured to quantify the effects of E2. To investigate developmental stage-specific effects, laboratory exposures of 1 μg/L E2 were initiated pre-hatching as eyed embryos or post-hatching upon entering the alevin stage.

Chronic toxicity of chloride to freshwater species: effects of hardness and implications for water quality guidelines.

Toxicity tests using nine freshwater species (Ceriodaphnia dubia, Daphnia magna, Oncorhynchus mykiss, Pimephales promelas, Lumbriculus variegatus, Tubifex tubifex, Chironomus dilutus, Hyallela azteca, and Brachionus calyciflorus) were conducted to evaluate their sensitivity to chloride. Acute-to-chronic ratios (ACRs) from these tests indicate the ACR of 7.59 employed by the United States Environmental Protection Agency (U.

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.

Aeration with carbon dioxide-supplemented air as a method to control pH drift in toxicity tests with effluents from wastewater treatment plants.

Environment Canada methods for acute toxicity tests with rainbow trout require continuous aeration of test solutions during exposure. Depending on the sample, this procedure can result in an increase in pH as dissolved carbon dioxide (CO2) is stripped from solution as a result of aeration. In samples that contain ammonia, the pH may increase to the point where the unionized fraction results in artifactual toxicity.

Identification of chlorfenvinphos toxicity in a municipal effluent in Sydney, New South Wales, Australia.

Acute toxicity in a municipal sewage treatment plant in Sydney, New South Wales, Australia, was traced to chlorfenvinphos, an organophosphorous pesticide. Toxicity identification evaluation procedures led to the tentative identification of chlorfenvinphos as the toxic contaminant in the sample. Subsequent analytical verification revealed 0.