Episodic release of arsenic, copper and chromium from a wood preservation site monitored by transplanted aquatic moss

Leaching from a wood preservation site in Norway, severely contaminated wit h copper (Cu), chromium (Cr) and arsenic (As), was investigated using aquat ic moss. The objectives were three-fold: (i) study the release of trace met als into a river during a rainfall episode, (ii) determine whether aquatic moss can be used to detect leaching during episodic events when sampling is frequent, and (iii) determine whether aquatic moss can be used as a bioind icator in brackish water. Aquatic moss (Fontinalis antipyretica was transpl anted into the river in eight moss-cages. Samples were collected during one episode of rainfall. Concentrations of As in the moss increased during the rainfall event. Cu and Cr concentrations in the moss increased during the beginning of the period, but tended to decrease because of dilution towards the end. Accumulation patterns of Cu, Cr and As in the moss varied probabl y because of differences in binding affinity to soil and to the moss. The u se of F: antipyretica proved that leaching of trace metals do increase duri ng a rainfall event. It was shown that aquatic moss can be used as an indic ator to monitor leaching during rainfall events, however, timing of samplin g is critical. Although the moss survived in brackish water, it is question ed whether ions in the water can cause competition and desorption of the me tals in the moss.