In situ and laboratory toxicity of coalbed natural gas produced waters with elevated sodium bicarbonate

Abstract

Some tributaries in the Powder River Structural Basin, USA, were historically ephemeral, but now contain water year round as a result of discharge of coalbed natural gas (CBNG)-produced waters. This presented the opportunity to study field sites with 100% effluent water with elevated concentrations of sodium bicarbonate. In situ experiments, static renewal experiments performed simultaneously with in situ experiments, and static renewal experiments performed with site water in the laboratory demonstrated that CBNG-produced water reduces survival of fathead minnow (Pimephales promelas) and pallid sturgeon (Scaphirhynchus albus). Age affected survival of fathead minnow, where fish 2 d posthatch (dph) were more sensitive than 6 dph fish, but pallid sturgeon survival was adversely affected at both 4 and 6 dph. This may have implications for acute assays that allow for the use of fish up to 14 dph. The survival of early lifestage fish is reduced significantly in the field when concentrations of NaHCO(3) rise to more than 1500 mg/L (also expressed as >1245 mg HCO(3) (-) /L). Treatment with the Higgin's Loop technology and dilution of untreated water increased survival in the laboratory. The mixing zones of the 3 outfalls studied ranged from approximately 800 m to 1200 m below the confluence. These experiments addressed the acute toxicity of effluent waters but did not address issues related to the volumes of water that may be added to the watershed.

Effects of artificial sweeteners on Lemna minor

“…Some studies described the toxicity of some of these additives, e.g. sodium bicarbonate to fish (Farag et al 2014;, or the effect of sodium bicarbonate on toxicity of uranium (Soudek et al 2011). Sucralose also has an effect on metal toxicity (Hu et al 2016).…”

An in situ toxicity identification and evaluation water analysis system: Laboratory validation

“…Current application of TIE methods relies heavily on laboratory‐based fractionation and exposure tests, which are subject to artifacts and variable biases . Some studies have paired in situ bioassays with laboratory TIE to corroborate results in a natural setting . While these pairings sometimes produce similar results, there are often drastic differences in survival rates between the 2 test groups, and the pattern is not consistent for all species or environments .…”

“…Furthermore, laboratory exposures of test organisms are constant and do not account for natural variables that may alter toxicity. Temporal variation in dissolved organic carbon, suspended solids, hardness, temperature, and pH can all affect the toxicity and bioavailability of metals and organics . The choice of sampling times could also affect the composition of the sample for laboratory tests, exposing test organisms to only a snapshot of stream conditions .…”