J. N. Ryan — Page 2

USGS1996

The reversibility of virus attachment to mineral surfaces

Virus transport through groundwater is limited by attachment to mineral surfaces and inactivation. Current virus transport models do not consider the implications of the reversibility of virus attachment to minerals. To explore the reversibility of virus attachment to mineral surfaces, we attached PRD1, a bacteriophage considered to be a good model of enteric viruses, to quartz and ferric oxyhydroxide-coated quartz surfaces over a range of pH values in equilibrium 'static columns'. Following attachment, we detached the viruses by replacing the pore solution with solutions of equal and higher pH. The extent of virus attachment followed an attachment 'edge' that occurred at a pH value about 2.5-3.5 pH units above the pH(IEP) of the mineral surfaces. Viruses attached below this edge were irreversibly attached until the pH of the detachment solution exceeded the pH value of the attachment edge. Viruses attached above this edge were reversibly attached. Derjaguin-Landau-Verwey-Overbeek (DEVO) potential energy calculations showed that the attachment edge occurred at the pH at which the potential energy of the primary minimum was near zero, implying that the position of the primary minimum (attractive or repulsive) controlled the equilibrium distribution of the viruses. The results suggest that the reversibility of virus attachment must be considered in virus transport models for accurate predictions of virus travel time.

Colloids and Surfaces A: Physicochemical and Engin↗

USGS1990

Metal and nutrient behavior in the Raritan estuary, New Jersey, U.S.A.: The effect of multiple freshwater and industrial waste inputs

A geochemical analysis of the Raritan estuary during high and low river flow is presented. Several statistical and graphical approaches, in addition to a hydrodynamic model of the Raritan estuary, are used to demonstrate the effects of lateral inputs on trace-element distribution in a complicated fluvial-marine system. Results from factor and cluster analysis show that nutrient-salinity distributions on both sampling dates are controlled primarily by freshwater-saltwater mixing. Industrial and municipal waste sources within the estuary are important in controlling dissolved organic carbon (at low flow) and dissolved and bottom sediment trace metals. Biological and physico-chemical reactions have a significant, but secondary effect on nutrient and trace-metal distributions with salinity. Apparent flux calculations and property-property plots show that for dissolved phosphate, nitrate and inorganic carbon, the Raritan estuary can be divided into two mixing zones, with the Raritan River controlling nutrient concentrations in the lower-salinity stretches and the South River controlling their distributions at intermediate and higher salinities. High enrichment factors of most metals in estuary bottom sediment reveal that this is an important and semi-permanent sink for trace metals in the Raritan system. Previous work on suspended sediment in the estuary and river substantiates that this load is also an important sink for trace metals; however, many of these metals are in leachable modes which are more susceptible to release and incorporation into the food chain. ?? 1990.

Chemical Geology↗