Mark River

Weyerhaeuser

Although human reshaping of the nitrogen (N) cycle is well established, contributions of individual N sources to riverine and coastal eutrophication are less certain. Urban N fluxes are potentially substantial, particularly from sewer overflows. Results from four longitudinal surveys in rivers in and around the city of Pittsburgh, Pennsylvania, wer...

The majority of annual sediment flux is transported during storm events in many watersheds across the world. Using X‐ray diffraction, we analyzed the mineralogy of grab samples of suspended sediment during different stages of storm hydrographs in the Southern Piedmont. Mineralogy of suspended sediment changes drastically from quartz‐dominated durin...

Increased dissolved reactive phosphorus (DRP) fluxes in the Maumee River in the Western Lake Erie watershed have been cited as a cause of recent hypoxia and toxic algal blooms in Western Lake Erie. Dissolved reactive P is operationally defined as the molybdate‐reactive P that passes through a 0.45‐μm filter. Unfortunately, this 0.45‐μm cutoff is no...

Recent research suggested that iron oxidation may protect carbon from drought-accelerated decomposition in wetlands by promoting the sorption of lignin derivatives and decreasing phenolic oxidase activities. Here we examined whether this mechanism exists in organic-rich peatlands, which store over 30% of the world's soil carbon, by simulating droug...

Authigenic nanoparticles containing iron (Fe) and phosphorus (P) have been identified at the anoxic/oxic interface of various aquatic ecosystems, forming upon the oxidation of reduced Fe. Little is known about the prevalence of these authigenic nanoparticles in streams, their impact on biogeochemical fluxes, or the bioavailability of P associated w...

Particulate phosphorus (PP) is often the largest component of the total phosphorus (P) load in stormwater. Fine-resolution measurement of particle sizes allows us to investigate the mechanisms behind the removal of PP in stormwater wetlands, since the diameter of particles influences the settling velocity and the amount of sorbed P on a particle. I...

Gulls have long been observed concentrating in flocks of tens to hundreds of thousands at the anthropogenic food sources provided by landfills. Yet, the biogeochemical implications of the landfill gull phenomenon have been largely ignored. This study has two goals: 1) to understand the magnitude and geographic extent of landfill gulls in North Amer...