The major organic forms of arsenic in fresh marine fish such as haddock, halibut, cod, herring, mackeral, sole, lobster, scallops, and shrimp obtained throughout Canada were identified as arsenobetaine and, in shrimp only, arsenocholine. Freshwater fish including pike, bass, carp, pickeral, whitefish, yellow perch, and striped perch contained no arsenobetaine or arsenocholine but did contain methanol-extractable arsenic, which has not yet been identified. Salmon obtained from British Columbia contained arsenobetaine and an unknown arsenic compound that eluted later from the reversed-phase HPLC system employed. The arsenobetaine levels for marine fish ranged from 0.15 to 15.8 Mg/g of fresh weight. The sample extraction included freeze drying the tissue and then Soxhlet extracting with chloroform (which was discarded) and then with methanol. The methanolic extract containing the organoarsenic compounds was purified by alumina and ion-exchange chromatography then subjected to reversed-phase highperformance liquid chromatography with off-line graphite furnace atomic absorption detection. The compounds were confirmed by mass spectrometry using fast atom bombardment. Arsenobetaine was also confirmed by derivatization to the ethyl ester with further characterization by HPLC and mass spectrometry.

Using fast atom bombardment (FAB) ionization combined with tandem mass spectrometry (MS/MS), the identity of arsenobetaine (AB) in extracts of sole, haddock, lobster and shrimp was unequivocally confirmed. Evidence was also presented for the presence of arsenocholine (AC) in the shrimp extract. Confirmation was obtained by comparing the collision-induced dissociation (CID) daughter ion and parent ion spectra of major ions in the FAB spectra from these extracts with those from the authentic standards.

A vanadium catalyzed pentoxide-sulfuric acid-nitric acid digestion procedure is described which gave higher values for total arsenic than the AOAC dry ash procedure with fish and shellfish tissue. Recoveries of added methylarsenic compounds were also lower by dry ashing procedures but essentially complete by the new ashing procedure. Arsenic levels in a variety of shellfish and fish tissues as determined by wet ashing averaged 6.3% higher than dry ash values. In lobster hepatopancreas the difference was 13.1% for a large number of samples from a number of sampling areas.

The concentrations of Bunker C fuel oil in the waters of Chedabucto Bay in April 1971, 14 months after the Arrow disaster, were uniformly low, averaging 1.5 ppb. Comparison with other data indicates that concentrations in the bay have dropped more than an order of magnitude in the last year and now are at a level that is typical for the concentration of petroleum residues in the marine waters off Atlantic Canada. Although practically all of the Bunker C originating from the Arrow appears to be gone from the water column, oil coverage is still extensive in some inshore areas and considerable quantities of sedimented oil are probably present in the sediments of the bay.

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