Search

The contamination status of the marine environment in Hong Kong was studied by measuring concentrations of organochlorine (OC) pollutants (i.e., hexachlorobenzene, aldrin, dieldrin, endrin, mirex, total heptachlor, total chlordane, total DDTs, total PCBs, and total toxaphenes) in the eggs of selected waterbird species from different locations around the city: Little Egret ( Egretta garzetta ) and Chinese Pond Heron ( Ardeola bacchus ) from Mai Po Village, Great Egret ( Ardea alba ) and Black-crowned Night Heron ( Nycticorax nycticorax ) from A Chau, and Chinese Pond Heron ( A. bacchus) from Ho Sheung Heung. The mean concentrations of total PCBs and total DDTs ranged from 191–11 100 ng g −1 lipid and 453–49 000 ng g −1 lipid, respectively. Recent exposure of waterbirds to technical chlordane was found in Hong Kong. The risk characterization demonstrated potential risks to birds associated with exposure to DDE, which was found to cause a reduction in survival of young in Hong Kong Ardeids based on the endpoint in the risk assessment.

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 C10–14n-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.

Progressively more stringent regulations on effluent toxicity to fish at a U. S. West Coast petroleum refinery have necessitated the use of granular activated carbon (GAC) treatment to further reduce effluent toxicity. Historical studies at this refinery have shown that organic (naphthenic) acids are the most consistent source of effluent toxicity to fish. This paper describes the use of supercritical fluid extraction (SFE) coupled with fast ion bombardment mass spectrometry (FIB-MS) to recover and characterize organic acids from activated carbon as a means to confirm toxicity reduction due to organic acid removal. The extracted organic acids yielded a molecular weight distribution corresponding to carboxylic/naphthenic acid ions which are similar to the distribution in spectra obtained from effluent extracts and commercially available standards. Since toxicity studies have demonstrated that the GAC is effective in removing the toxic components in the effluent, the recovery of naphthenic acids from the GAC lends support that these compounds are the source of fish toxicity.

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.