ARSENIC COMPOUNDS IN A MARINE FOOD-CHAIN

A three-organism food chain within a rock pool at Rosedale, NSW, Austr alia, was investigated with respect to arsenic compounds by high perfo rmance liquid chromatography - hydraulic high pressure nebulization - inductively coupled plasma mass spectrometry (HPLC-HHPN-ICP-MS). Total arsenic concentration was determined in the seaweed Hormosira banksii (27.2 mu g/g dry mass), in the gastropod Austrocochlea constricta (74 .4 mu g/g dry mass), which consumes the seaweed, and in the gastropod Morula marginalba (233 mu g/g dry mass), which eats Austrocochlea cons tricta. The major arsenic compounds in the seaweed were methyl[1-O-(2' ,3'-dihydroxypropyl)-5-deoxy-beta-D- ribofuranos-5-yl]arsine oxide and an unidentified compound. The herbivorous gastropod Austrocochlea con stricta transformed most of the arsenic taken up with the seaweed to a rsenobetaine. Traces of arsenite, arsenate, dimethylarsinic acid, arse nocholine, the tetramethylarsonium cation, and several unknown arsenic compounds were detected. Arsenobetaine accounted for 95% of the arsen ic in the carnivorous gastropod Morula marginalba. In Morula marginalb a the concentration of arsenocholine was higher, and the concentration s of the minor arsenic compounds lower than in the herbivorous gastrop od Austrocochlea constricta.