Physico-chemical properties of substances used as molluscicides: precipitation and adsorption.

When molluscicide solutions are applied to natural waters, the active substance may be precipitated or adsorbed and its concentration in the water thus rapidly reduced below the effective minimum. In this paper the authors describe experiments in which factors affecting loss by precipitation and adsorption were examined separately for a number of molluscicidal chemicals. It was found that the amount lost by precipitation depended on the pH of the water and that at a given pH there was a maximum amount of chemical that would remain in solution. The amount lost by adsorption on a standard adsorbent (filter-paper) appeared to be negligible with certain compounds, but with others it was found to depend both on the salt content and on the pH of the water, decreasing with increased dissolved solids and increased pH. It is therefore essential to take into consideration the pH and turbidity of the water before applying molluscicidal treatment.