Water Resources Research Act Program

Details for Project ID 2018MT328B

Student Research: Interactive effects of metal and nutrient cycling in the Upper Clark Fork River, Montana

Institute: Montana
Year Established: 2018 Start Date: 2018-03-01 End Date: 2019-02-28
Total Federal Funds: $1,610 Total Non-Federal Funds: $725

Principal Investigators: Kaitlin Perkins

Abstract: The same aquatic ecosystems on which we rely for clean surface water for household use are being exposed to an ever-increasing variety of contaminants. In Montana, nutrients from agriculture and metal/metalloid pollutants from mineral resource extraction have contributed to the majority of rivers and streams under observation to be classified as impaired. In fact, metals and nutrients are ten of the top fifteen causes of impairment of Montana rivers2, resulting in deleterious effects on the abundance and biodiversity of organisms including periphyton (the base of the food web, consisting of algae, bacteria, archaea, and protists), up through benthic macroinvertebrates, fish, and terrestrial predators such as osprey and eagles. While much is known about the effects of isolated metal or nutrient contaminants on individual organisms in laboratory experiments, much less is understood about the impacts of these pollutants in mixtures exposed to diverse communities in the field. This disconnect between experiments and real systems is further complicated by the observation that metal(loid) pollution, long assumed to be either in the form of large unavailable particles or bioavailable dissolved solutes, may actually be moving downstream as nanoparticles (1 - 100 nm) and small colloids (100 – 450 nm), which do not settle readily from the water column. Instead, they are very efficiently removed by the periphyton and thus enter food webs where they can bioaccumulate in top predators like fish and osprey, even finding their way into humans through fish consumption, posing a potential health risk. I hypothesize that much of the metal(loid)s and nutrients in the Upper Clark Fork River (UCFR) at baseflow are associated with the small colloidal/nanoparticle fractions due to their high reactive surface area. Furthermore, I hypothesize that metal(loid) uptake into the periphyton is driven by uptake of small colloids and nanoparticles, given patterns observed with engineered nanomaterials. Finally, I hypothesize that increased nutrient availability may increase periphyton growth, lowering periphyton metal(loid) concentrations and transfer to higher trophic levels.