pH and thiosulfate dependent microbial sulfur oxidation strategies across diverse environments.

Sulfur oxidizing bacteria (SOB) play a key role in sulfur cycling in mine tailings impoundment (TI) waters, where sulfur concentrations are typically high. However, our understanding of SOB sulfur cycling via potential S oxidation pathways (, r, and SI) in these globally ubiquitous contexts, remains limited. Here, we identified TI water column SOB community composition, metagenomics derived metabolic repertoires, physicochemistry, and aqueous sulfur concentration and speciation in four Canadian base metal mine, circumneutral-alkaline TIs over four years (2016 - 2019).

The Influence of Micronutrient Trace Metals on Growth and Toxin Production.

is a widespread cyanobacteria capable of producing hepatotoxic microcystins. Understanding the environmental factors that influence its growth and toxin production is essential to managing the negative effects on freshwater systems. Some micronutrients are important cofactors in cyanobacterial proteins and can influence cyanobacterial growth when availability is limited.

Severe cyanobacterial blooms in an Australian lake; causes and factors controlling succession patterns.

Cyanobacterial blooms have major impacts on the ecological integrity and anthropogenic value of freshwater systems. Chrysosporum ovalisporum, a potentially toxic cyanobacteria has been rare in Australian waters until recently when is has bloomed in a number of lake and river systems. The aim of this study was to determine drivers of its growth and growing dominance.

Sorption, degradation and microbial toxicity of chemicals associated with hydraulic fracturing fluid and produced water in soils.

Spills of hydraulic fracturing (HF) fluids and of produced water during unconventional gas extraction operations may cause soil contamination. We studied the degradation and microbial toxicity of selected HF chemical components including two biocides (methylisothiozolinone- MIT, chloromethylisothiozolinone- CMIT), a gel-breaker aid (triethanolamine -TEA), and three geogenic chemicals (phenol, m-cresol and p-cresol) in ultrapure water, HF fluid and produced water in five different soil types (surface and subsurface soils). The degradation of the two biocides (in soils treated with HF fluid or ultrapure water) and of the three geogenic chemicals (in soils treated with produced water) was rapid (in all cases DT values < 2 days in surface soils).

Assessing the importance of cobalt as a micronutrient for freshwater cyanobacteria.

Micronutrients play key roles in numerous metabolic processes in cyanobacteria. However, our understanding of whether the micronutrient cobalt influences the productivity of freshwater systems or the occurrence of cyanobacterial blooms is limited. This study aimed to quantify the concentration of Co necessary for optimal cyanobacterial growth by exposing Microcystis aeruginosa to a range of Co concentrations under culture conditions.

New Insights Into Sulfur Metabolism Through Coupled Gene Expression, Solution Chemistry, Microscopy, and Spectroscopy Analyses.

Here, we experimentally expand understanding of the reactions and enzymes involved in ATCC 19377 S and metabolism by developing models that integrate gene expression analyzed by RNA-Seq, solution sulfur speciation, electron microscopy and spectroscopy. The metabolism model involves the conversion of to , S and mediated by the sulfur oxidase complex (Sox), tetrathionate hydrolase (TetH), sulfide quinone reductase (Sqr), and heterodisulfate reductase (Hdr) proteins. These same proteins, with the addition of rhodanese (Rhd), were identified to convert S to , and polythionates in the S metabolism model.

A Review of the Effect of Trace Metals on Freshwater Cyanobacterial Growth and Toxin Production.

Cyanobacterial blooms are becoming more common in freshwater systems, causing ecological degradation and human health risks through exposure to cyanotoxins. The role of phosphorus and nitrogen in cyanobacterial bloom formation is well documented and these are regularly the focus of management plans. There is also strong evidence that trace metals are required for a wide range of cellular processes, however their importance as a limiting factor of cyanobacterial growth in ecological systems is unclear.

Toxicity of dissolved and precipitated forms of barium to a freshwater alga (Chlorella sp. 12) and water flea (Ceriodaphnia dubia).

Barium is present at elevated concentrations in oil and gas produced waters, and there is no international water quality guideline value to assess the potential risk of adverse effects to aquatic biota. Sulfate concentration largely controls the solubility of barium in aquatic systems, with insoluble barium sulfate (barite) assumed to be less bioavailable and less toxic than dissolved barium. We exposed aquatic biota to dissolved barium only and to a mixture of dissolved and precipitated barium.

On the mechanism of nanoparticulate CeO2 toxicity to freshwater algae.

The factors affecting the chronic (72-h) toxicity of three nanoparticulate (10-34nm) and one micron-sized form of CeO2 to the green alga, Pseudokirchneriella subcapitata were investigated. To characterise transformations in solution, hydrodynamic diameters (HDD) were measured by dynamic light scatter, zeta potential values by electrophoretic mobility, and dissolution by equilibrium dialysis. The protective effects of humic and fulvic dissolved organic carbon (DOC) on toxicity were also assessed.

Derivation of a water quality guideline for aluminium in marine waters.

Metal risk assessment of industrialized harbors and coastal marine waters requires the application of robust water quality guidelines to determine the likelihood of biological impacts. Currently there is no such guideline available for aluminium in marine waters. A water quality guideline of 24 µg total Al/L has been developed for aluminium in marine waters based on chronic 10% inhibition or effect concentrations (IC10 or EC10) and no-observed-effect concentrations (NOECs) from 11 species (2 literature values and 9 species tested including temperate and tropical species) representing 6 taxonomic groups.

Transformations of nanomaterials in the environment.

Increasing use of engineered nanomaterials with novel properties relative to their bulk counterparts has generated a need to define their behaviors and impacts in the environment. The high surface area to volume ratio of nanoparticles results in highly reactive and physiochemically dynamic materials in environmental media. Many transformations, e.

Comparative toxicity of nanoparticulate ZnO, bulk ZnO, and ZnCl2 to a freshwater microalga (Pseudokirchneriella subcapitata): the importance of particle solubility.

Metal oxide nanoparticles are finding increasing application in various commercial products, leading to concerns for their environmental fate and potential toxicity. It is generally assumed that nanoparticles will persist as small particles in aquatic systems and that their bioavailability could be significantly greater than that of larger particles. The current study using nanoparticulate ZnO (ca.

Azo dye method for mapping relative sediment enzyme activity in situ at precise spatial locations.

Existing methodology for measuring microbial enzyme activity in aquatic sediments involves horizontal sectioning of sediment cores into centimeter slices, followed by determination of the enzyme activity of each homogenized sediment slice. At best, this approach provides only one-dimensional information on the distribution of microbial activity. This paper describes the development of a novel technique to map sediment enzyme activity in situ at millimeter spatial resolution.