A5006302282- Marine and coastal ecosystems
- Marine Biology and Ecology Research
- Toxic Organic Pollutants Impact
- Isotope Analysis in Ecology
- Heavy metals in environment
- Geology and Paleoclimatology Research
- Marine Bivalve and Aquaculture Studies
- Environmental Toxicology and Ecotoxicology
- Clay minerals and soil interactions
- Aquatic Ecosystems and Phytoplankton Dynamics
- Microbial Community Ecology and Physiology
- Marine and fisheries research
- Methane Hydrates and Related Phenomena
- Soil and Water Nutrient Dynamics
- Coastal wetland ecosystem dynamics
- Geochemistry and Elemental Analysis
- Ocean Acidification Effects and Responses
- Groundwater and Isotope Geochemistry
- Soil and Unsaturated Flow
- Soil Carbon and Nitrogen Dynamics
- Radioactive element chemistry and processing
- Marine and environmental studies
- Water Quality and Pollution Assessment
- Aquaculture Nutrition and Growth
- Effects and risks of endocrine disrupting chemicals
University of Maine
2010-2024
University of Maine System
2002-2011
Maine Medical Center
1992-2008
University of California, Riverside
2006
University of Maryland, Baltimore
2003
University of Maryland Center for Environmental Science
1999
Woods Hole Oceanographic Institution
1998
Stony Brook University
1998
Université de Bordeaux
1996
University of Washington
1996
An enigmatic stepwise increase in oxygen the late Precambrian is widely considered a prerequisite for expansion of animal life. Accumulation requires organic matter burial sediments, which largely controlled by sheltering or preservational effects detrital clay minerals modern marine continental margin depocenters. Here, we show mineralogical and geochemical evidence an mineral deposition Neoproterozoic that immediately predated first metazoans. Today most originate biologically active...
The principle of lost opportunity from optimal foraging theory, coupled with recent information about fluxes in the deep sea, allows prediction feeding behaviours potentially specific to deep-sea deposit feeders. One possible strategy, thus far documented only indirectly, is ‘ squirrel ’ away rich food seasonal or episodic pulses that recently have been shown fuel meiofaunal growth. Echiurans and sipunculids show morphological faecal handling patterns consonant this suggestion. Where it...
Contaminants in sediments are less available than their concentrations might imply, but measures of this availability have been generally lacking. Sediments ingested by benthic animals can be expected to undergo a unique chemical environment controlled the digestive chemistry organism. We measured solubilization sedimentary contaminantsCu, Pb, and polycyclic aromatic hydrocarbons (PAH)by fluids extracted from marine invertebrates. Bioavailability these contaminants, thus measured, is small...
Soil organic matter (OM) and mineral surfaces are intimately related, affecting the dynamics of each their reactivity with many environmentally important substances. We examined coverage by OM in acid soils Massachusetts. Specific surface areas controlled a combination clay sesquioxide contents. Subsurface horizons, especially C horizons pH 4.6 to 4.8, contained phase significant microporosity (pores <2 nm) that could be eliminated 350°C muffling. Organic (OC) concentrations surficial (A, O)...
Seasonal changes in total bacterial numbers and their associated mucus coatings surficial sediments were examined. Bacterial followed the temperature cycle, with highest summer. The specific surface areas of measured rather than inferred from other granulometric properties; proportional to only for sample suites collected at same time. Bacteria inhabited shallow depressions on sand silt grains; they not found grains smaller about 10 µ m or inside pores like those weathered feldspar grains....
We developed a biomimetic approach, based on direct incubation with proteolytic enzymes, to measure bioavailable amino acids in sediments. The kinetics of release monomers and oligopeptides, which are amenable absorption by cells, is measured as either individual or total acids. Microbial proteases incubated fresh sediments yield at similar rate gut juices from deposit‐feeding holothuroid. Amino acid sediment was dominated slow hydrolysis step refractory substrate, can be described...
The benthic environment of the Gulf Maine is characterized by a thick and basin‐wide nepheloid layer, classically defined as near‐bottom region permanent sediment resuspension. high frequency commercial bottom trawling in particular regions Maine, documented records compiled National Marine Fisheries Service, may strongly affect measured resuspension fluxes contribute to maintenance layer. Indirect evidence effects on observed seasonal collection large, infaunal worms, along with substantial...
Abstract The sediment-water interface in the coastal ocean is a highly dynamic zone controlling biogeochemical fluxes of greenhouse gases, nutrients, and metals. Processes sediment mixed layer (SML) control transfer reactivity both particulate dissolved matter interfaces. Here we map global distribution SML based on excess 210 Pb ( ex ) profiles then use neural network model to upscale these observations. We show that regions such as large estuaries have thicker SMLs than most oceanic...
Hydrolytic enzyme activity, surfactancy, and dissolved organic matter in the digestive lumens of 19 benthic echinoderm polychaete species were examined, using consistent quantifiable methods. Enzyme activities compared with those extracellular enzymes from ambient sediments. ranged over five orders magnitude, averages decreasing order polychaetes > echinoderms sediment. Highest animals usually associated fluid phase midgut sections, posteriorward decreases indicating little export to...
Total nitrogen (TN) loadings in riverine sediments and their coastal depocenters were compared for 11 river systems worldwide to assess the potential impact of particulates on budgets. Strong relationships between sediment specific surface area TN allow these impacts be estimated without intense sampling normally required achieve such About half showed higher than those from depocenter. In spite uncertainties, comparisons indicate that large, turbid rivers, as Amazon, Huanghe, Mississippi,...
Irradiation of particulate organic matter (POM) at light intensities found the earth's surface should induce reduction in molecular weight, as for dissolved matter, and hence result transfer to phase. We studied Mississippi River suspended sediments test if photodissolution can losses POM similar those observed between delivery burial coastal sediments. experiments a solar simulator demonstrated dissolution tens percent after several days exposure strong sunlight. Neither water type nor iron...