BIOAVAILABLE PHOSPHORUS IN PULP AND PAPER MILL EFFLUENTS: FINDINGS FROM ALGAL GROWTH ASSAYS FOR IMPROVED WATER QUALITY MANAGEMENT TARGETS
Weak quantitative relationships between phosphorus and algae growth can confound the development of sound water quality management tools (e.g. TMDLs). This may be because some phosphorus in runoff, wastewaters, and the system itself may be unavailable to algae, or become available only after extended time in the environment. We quantified and characterized phosphorus bioavailability in paper mill effluents (n=4) using an algal assay in which effluent or controls were inoculated with phosphorus-starved algae and placed under ideal conditions until growth ceased. Algae were removed, and solutions reinoculated with phosphorus-starved algae and allowed to grow. This process repeated until growth ceased completely, with the residual phosphorus representing the non-bioavailable fraction. The difference between the solution’s initial phosphorus concentration and this non-available phosphorus represented the bioavailable phosphorus. Uptake of available effluent phosphorus took >40 days and 4-6 cycles of addition/removal of phosphorus-starved algae, with 8-16% of effluent phosphorus unavailable for algal growth. Further analyses suggest that non-bioavailable phosphorus may be colloidal, and associated with non/slowly-available humic metal-phosphorus complexes. These findings have important implications for the development of effective nutrient-response linkages, and more robust water quality management targets.
Camille Flinders (Primary Presenter/Author), NCASI, firstname.lastname@example.org;
Jim Palumbo (Co-Presenter/Co-Author), ncasi, email@example.com;