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

The Next Frontier of Environmental Unknowns: Substances of Unknown or Variable Composition, Complex Reaction Products, or Biological Materials (UVCBs)

Substances of unknown or variable composition, complex reaction products, or biological materials (UVCBs) are over 70 000 "complex" chemical mixtures produced and used at significant levels worldwide. Due to their unknown or variable composition, applying chemical assessments originally developed for individual compounds to UVCBs is challenging, which impedes sound management of these substances. Across the analytical sciences, toxicology, cheminformatics, and regulatory practice, new approaches addressing specific aspects of UVCB assessment are being developed, albeit in a fragmented manner. This review attempts to convey the "big picture" of the state of the art in dealing with UVCBs by holistically examining UVCB characterization and chemical identity representation, as well as hazard, exposure, and risk assessment. Overall, information gaps on chemical identities underpin the fundamental challenges concerning UVCBs, and better reporting and substance characterization efforts are needed to support subsequent chemical assessments. To this end, an information level scheme for improved UVCB data collection and management within databases is proposed. The development of UVCB testing shows early progress, in line with three main methods: whole substance, known constituents, and fraction profiling. For toxicity assessment, one option is a whole-mixture testing approach. If the identities of (many) constituents are known, grouping, read across, and mixture toxicity modeling represent complementary approaches to overcome data gaps in toxicity assessment. This review highlights continued needs for concerted efforts from all stakeholders to ensure proper assessment and sound management of UVCBs.

Fire Suppression Agents Combined with Gasoline in Aquatic Ecosystems: A Mixture Approach

Fire suppression agents are recommended for extinguishing fires by flammable liquids and frequently end in water bodies, combined with the fuels. There is a lack of toxicity information on these commercial formulations and the effects of mixtures of fire suppression agents and fuels. The aim of the present study was to evaluate the toxic effects of different fire suppression agents, the gasoline water-soluble fraction (GWSF), and mixtures of each fire suppression agent and GWSF. Individual tests were performed with Daphnia similis and Artemia sp.; the most toxic fire suppression agents to D. similis and Artemia sp. were F-500®, Cold Fire®, Agefoam®, and Kidde Sintex® 1%; the GWSF was the least toxic. The concentration addition model was used to predict the mixture effects and evaluate synergism/antagonism, dose ratio dependence, and dose level dependence. Cold Fire with GWSF showed dose level deviation to D. similis, marked mainly by synergism; for Artemia sp., the dose ratio pattern was predicted, with a synergistic response mainly by Cold Fire. Agefoam and GWSF behaved additively for D. similis and dose ratio for Artemia sp., with synergism being caused by Agefoam. Kidde Sintex 1% with GWSF were dose ratio for both organisms, with Kidde Sintex 1% being responsible for synergism. Our results show that some mixtures of fire suppression agents and GWSF may cause toxicity to aquatic organisms, posing risk in a real environmental scenario, such as a major fire combat. Environ Toxicol Chem 2021;40:767-779. © 2020 SETAC.

Occurrence, toxicity and ecological risk of larvicidal oil in the coastal marine ecosystem of Hong Kong

Application of larvicidal oil (LO) is the most common practice in Hong Kong to control mosquitos, and hence prevent mosquito-borne diseases and protect human health. Globally, this study represented the first comprehensive assessment of toxicity and risk posed by LO to marine organisms. We found concentrations of LO ranged from 0.08 to 0.66 mg/L in coastal seawaters of Hong Kong. Waterborne exposure to water-accommodated fractions of LO resulted in growth inhibition to two microalgal species (72-h EC₅₀: 1.92-2.90 mg/L) and acute mortality to three marine animals (96-h LC₅₀: 3.41-8.10 mg/L). From these toxicity results, a concentration that considered to be hazardous to 5% of species (HC₅) was predicted at 1.45 mg/L, while the predicted no-effect concentration was determined to be 0.29 mg/L. The hazard quotient of LO exceeded 1 at 9 out of 15 sites, indicating moderate-to-high ecological risk to exposure of LO in the marine environment of Hong Kong.

Chemical and ecotoxicological properties of three bio-oils from pyrolysis of biomasses

In view of the potential use of pyrolysis-based technologies, it is crucial to understand the environmental hazards of pyrolysis-derived products, in particular bio-oils. Here, three bio-oils were produced from fast pyrolysis of pine wood and intermediate pyrolysis of corn stalk and poultry litter. They were fully characterized by chemical analysis and tested for their biodegradability and their ecotoxicity on the crustacean Daphnia magna and the green alga Raphidocelis subcapitata. These tests were chosen as required by the European REACH regulation. These three bio-oils were biodegradable, with 40-60% of biodegradation after 28 days, and had EC50 values above 100mgL(-1) for the crustacean and above 10mgL(-1) for the alga, showing low toxicity to the aquatic life. The toxic unit approach was applied to verify whether the observed toxicity could be predicted from the data available for the substances detected in the bio-oils. The predicted values largely underestimated the experimental values.

Assessing fuel spill risks in polar waters: Temporal dynamics and behaviour of hydrocarbons from Antarctic diesel, marine gas oil and residual fuel oil

As part of risk assessment of fuel oil spills in Antarctic and subantarctic waters, this study describes partitioning of hydrocarbons from three fuels (Special Antarctic Blend diesel, SAB; marine gas oil, MGO; and intermediate grade fuel oil, IFO 180) into seawater at 0 and 5°C and subsequent depletion over 7days. Initial total hydrocarbon content (THC) of water accommodated fraction (WAF) in seawater was highest for SAB. Rates of THC loss and proportions in equivalent carbon number fractions differed between fuels and over time. THC was most persistent in IFO 180 WAFs and most rapidly depleted in MGO WAF, with depletion for SAB WAF strongly affected by temperature. Concentration and composition remained proportionate in dilution series over time. This study significantly enhances our understanding of fuel behaviour in Antarctic and subantarctic waters, enabling improved predictions for estimates of sensitivities of marine organisms to toxic contaminants from fuels in the region.

Evaluating the primary and ready biodegradability of dianilinodithiophosphoric acid

Dianilinodithiophosphoric acid (DDA) is widely used as sulfide mineral flotation collector in China. It is necessary to investigate the biodegradability of DDA to provide the fundamental knowledge to assess the environmental fate in the risk assessment of DDA and to design and operate the DDA flotation wastewater biological treatment plant. In the present study, the primary and ready aerobic biodegradations of DDA were studied and the primary biodegradation kinetic model of DDA was developed. The results show that DDA displays a good primary biodegradability and its biodegradation ratio reaches 99.8 % in 7 days. In contrast, DDA is not easily ready biodegradable; hence, it is a partially biodegradable organic compound. The primary aerobic biodegradation kinetics can be described using the first-order reaction kinetics equation: C = 19.72191e(-0.01513t).

Oil spill dispersants: boon or bane?

Dispersants provide a reliable large-scale response to catastrophic oil spills that can be used when the preferable option of recapturing the oil cannot be achieved. By allowing even mild wave action to disperse floating oil into tiny droplets (<70 μm) in the water column, seabirds, reptiles, and mammals are protected from lethal oiling at the surface, and microbial biodegradation is dramatically increased. Recent work has clarified how dramatic this increase is likely to be: beached oil has an environmental residence of years, whereas dispersed oil has a half-life of weeks. Oil spill response operations endorse the concept of net environmental benefit, that any environmental costs imposed by a response technique must be outweighed by the likely benefits. This critical review discusses the potential environmental debits and credits from dispersant use and concludes that, in most cases, the potential environmental costs of adding these chemicals to a polluted area are likely outweighed by the much shorter residence time, and hence integrated environmental impact, of the spilled oil in the environment.

Gasoline toxicology: overview of regulatory and product stewardship programs

Significant efforts have been made to characterize the toxicological properties of gasoline. There have been both mandatory and voluntary toxicology testing programs to generate hazard characterization data for gasoline, the refinery process streams used to blend gasoline, and individual chemical constituents found in gasoline. The Clean Air Act (CAA) (Clean Air Act, 2012: § 7401, et seq.) is the primary tool for the U.S. Environmental Protection Agency (EPA) to regulate gasoline and this supplement presents the results of the Section 211(b) Alternative Tier 2 studies required for CAA Fuel and Fuel Additive registration. Gasoline blending streams have also been evaluated by EPA under the voluntary High Production Volume (HPV) Challenge Program through which the petroleum industry provide data on over 80 refinery streams used in gasoline. Product stewardship efforts by companies and associations such as the American Petroleum Institute (API), Conservation of Clean Air and Water Europe (CONCAWE), and the Petroleum Product Stewardship Council (PPSC) have contributed a significant amount of hazard characterization data on gasoline and related substances. The hazard of gasoline and anticipated exposure to gasoline vapor has been well characterized for risk assessment purposes.