Aquatic hazard assessment of a commercial sample of naphthenic acids.

This paper presents chemical composition and aquatic toxicity characteristics of a commercial sample of naphthenic acids (NAs). Naphthenic acids are derived from the refining of petroleum middle distillates and can contribute to refinery effluent toxicity. NAs are also present in oil sands process-affected water (OSPW), but differences in the NAs compositions from these sources precludes using a common aquatic toxicity dataset to represent the aquatic hazards of NAs from both origins. Our chemical characterization of a commercial sample of NAs showed it to contain in order of abundance, 1-ring>2-ring>acyclic>3-ring acids (∼84%). Also present were monoaromatic acids (7%) and non-acids (9%, polyaromatic hydrocarbons and sulfur heterocyclic compounds). While the acyclic acids were only the third most abundant group, the five most abundant individual compounds were identified as C(10-14) n-acids (n-decanoic acid to n-tetradecanoic acid). Aquatic toxicity testing of fish (Pimephales promelas), invertebrate (Daphnia magna), algae (Pseudokirchneriella subcapitata), and bacteria (Vibrio fischeri) showed P. promelas to be the most sensitive species with 96-h LL50=9.0 mg L(-1) (LC50=5.6 mg L(-1)). Acute EL50 values for the other species ranged 24-46 mg L(-1) (EC50 values ranged 20-30 mg L(-1)). Biomimetic extraction via solid-phase-microextraction (BE-SPME) suggested a nonpolar narcosis mode of toxic action for D. magna, P. subcapitata, and V. fischeri. The BE analysis under-predicted fish toxicity, which indicates that a specific mode of action, besides narcosis, may be a factor for fishes.

Aquatic hazard and biodegradability of light and middle atmospheric distillate petroleum streams.

Light and middle atmospheric distillate petroleum substances are blended to produce fuels used in transportation and heating. These substances represent the majority by volume of crude oil refined products in the United States. The goal of this research was to develop biodegradability and aquatic toxicity data for four substances; heavy, straight-run naphtha (HSRN), hydro-desulfurized kerosene (HDK), hydro-cracked gas oil (HCGO), and catalytic-cracked gas oil (CCGO). Ready biodegradability tests demonstrated rapid and extensive microbial oxidation of these test substances, indicating a lack of persistence in the aquatic environment. Differences in biodegradation patterns reflected compositional differences in the constituent hydrocarbons. Results of aquatic toxicity tests on alga, cladocera, and fish demonstrated that toxicity was greatest for catalytic-cracked gas oil, which contained a high proportion of aromatic hydrocarbons. Aromatic hydrocarbons are more soluble, and hence more bioavailable, resulting in higher toxicity. When expressed on the basis of loading rates, acute toxicity values (LL/EL50) ranged between 0.3 and 5.5 mg L(-1) for all three species, while chronic no-observed-effect loading rates (NOELR) ranged between 0.05 and 0.64 mg L(-1). PETROTOX estimates for acute and chronic toxicity ranged from 0.18 to 2.3 mg L(-1) and 0.06 to 0.14 mg L(-1), respectively, which were generally more conservative than experimental data.

Toxicological assessment of green petroleum coke.

Green petroleum coke is primarily inorganic carbon with some entrained volatile hydrocarbon material. As part of the petroleum industry response to the high production volume challenge program, the potential for reproductive effects was assessed in a subchronic toxicity/reproductive toxicity screening test in rats (OECD 421). The repeated-dose portion of the study provided evidence for dust accumulation and inflammatory responses in rats exposed to 100 and 300 mg/m(3) but there were no effects at 30 mg/m(3). In the reproductive toxicity screen, the frequency of successful matings was reduced in the high exposure group (300 mg/m(3)) and was not significantly different from control values but was outside the historical experience of the laboratory. The postnatal observations (external macroscopic examination, body weight, and survival) did not indicate any treatment-related differences. Additional tests conducted to assess the potential hazards to aquatic (fish, invertebrates, and algae) and soil dwelling organisms (earthworms and vascular plants) showed few effects at the maximum loading rates of 1000 mg coke/L in aquatic studies and 1000 mg coke/kg soil in terrestrial studies. The only statistically significant finding was an inhibition of algal growth measured as either biomass or growth rate.