Papers by John Michael Trapp
While the presence of fecal indicator bacteria
such as Escherichia coli in urban stormwater has b... more While the presence of fecal indicator bacteria
such as Escherichia coli in urban stormwater has been
widely documented, their occurrence and persistence in
sediments are not as well understood. Recent investigations
suggest that E. coli can accumulate in drainage
basin sediments and act as a fecal bacterial reservoir
within a watershed. We investigate the prevalence of
E. coli populations in a tidal creek stormwater catchment
and examine their interaction with overlying
stormwater under wet and dry weather conditions.
Two rain events are sampled more intensively with
samples collected prior to, during, and after rainfall to
profile bacteria in each matrix throughout a storm.
Results of profile sampling and estimates of sediment
resuspension provide evidence for E. coli accumulation
during dry conditions and entrainment in overlying waters
during storm conditions. Profile results suggest the
occurrence of steady-state E. coli populations in drainage
basin sediments.
The oxidation of nanomolar levels of iron(II) with oxygen has been studied in NaCl solutions as a... more The oxidation of nanomolar levels of iron(II) with oxygen has been studied in NaCl solutions as a function of temperature (0 to 50°C), ionic strength (0.7 to 5.6 mol·kg −1 ), pH (6 to 8) and concentration of added NaHCO 3 (0 to 10 mmol·kg −1 ). The results have been fitted to the overall rate equation:
We present measurements of the solubility of Fe(II) and Fe(III) extracted from bulk and size- fra... more We present measurements of the solubility of Fe(II) and Fe(III) extracted from bulk and size- fractionated African dust collected in summer trade winds at Barbados, West Indies. Iron solubilities typically ranged from 1% to 3%. Fe(III) dominates the iron solubility over the entire range of particle sizes. At mineral dust concentrations below about 5 ug/m3 Fe(II), believed to be largely derived from anthropogenic and biomass burning sources, becomes increasingly important. Samples containing large soluble iron fractions and high Fe(II)/Fe(III) ratios are associated with South Atlantic back trajectories; the gray coloration of the filters suggests that the source may be biomass burning in southern Africa. In general, much of the variability in Fe solubility is linked to Fe(II) concentration changes. Vanadium is often used as a tracer of anthropogenic impacts. Although many of our samples yielded V/Ti ratios much greater than average crustal abundances, we could find no relationship between the enrichment of V and Fe solubility. Our Fe solubility results are quite similar to those obtained by others despite the fact that the measurements were made in diverse ocean regions and the protocols used were quite different in all cases. This uniformity implies that the factors controlling aerosol iron solubility are largely inherent in the properties of the aerosols themselves and not the procedures used to extract the iron. Our results suggest that dust transport models that focus on the role of iron in ocean biogeochemistry must take into account aerosol origin in order to better model the solubility of iron.
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Papers by John Michael Trapp
such as Escherichia coli in urban stormwater has been
widely documented, their occurrence and persistence in
sediments are not as well understood. Recent investigations
suggest that E. coli can accumulate in drainage
basin sediments and act as a fecal bacterial reservoir
within a watershed. We investigate the prevalence of
E. coli populations in a tidal creek stormwater catchment
and examine their interaction with overlying
stormwater under wet and dry weather conditions.
Two rain events are sampled more intensively with
samples collected prior to, during, and after rainfall to
profile bacteria in each matrix throughout a storm.
Results of profile sampling and estimates of sediment
resuspension provide evidence for E. coli accumulation
during dry conditions and entrainment in overlying waters
during storm conditions. Profile results suggest the
occurrence of steady-state E. coli populations in drainage
basin sediments.
such as Escherichia coli in urban stormwater has been
widely documented, their occurrence and persistence in
sediments are not as well understood. Recent investigations
suggest that E. coli can accumulate in drainage
basin sediments and act as a fecal bacterial reservoir
within a watershed. We investigate the prevalence of
E. coli populations in a tidal creek stormwater catchment
and examine their interaction with overlying
stormwater under wet and dry weather conditions.
Two rain events are sampled more intensively with
samples collected prior to, during, and after rainfall to
profile bacteria in each matrix throughout a storm.
Results of profile sampling and estimates of sediment
resuspension provide evidence for E. coli accumulation
during dry conditions and entrainment in overlying waters
during storm conditions. Profile results suggest the
occurrence of steady-state E. coli populations in drainage
basin sediments.