Concentration and phase speciation of Ag in selected
Texas rivers and in the Trinity River estuary were
measured
in order to establish the major factors that control its
fate
in the aquatic environment from source to sink.
Concentrations of Ag in the filter-passing fractions in
Texas
rivers ranged from <0.01 to 62 ng/L. In the Trinity
River
estuary (Galveston Bay), they ranged from 0.4 to 6.4 ng/L
and
showed a non-conservative estuarine mixing behavior.
An internal source of filter-passing (≤0.45 μm) and
colloidal
(1 kDa−0.45 μm) Ag was observed in the upper Trinity
Bay. Silver, associated with colloidal macromolecular
organic
matter, which was isolated using cross-flow
ultrafiltration
techniques, amounted to 15−70% of the filtered (≤0.45
μm) Ag concentration, decreasing with increasing
salinity.
Such a trend was similar to that of dissolved and
colloidal
organic carbon. Estuarine distributions of colloidal Ag
were
also broadly similar to those of suspended particulate
matter. The ratio of colloidal Ag to filter-passing Ag
was
similar to the ratio of colloidal organic carbon to total
dissolved organic carbon, suggesting not only that Ag is
complexed by organic macromolecules but also that
functional
groups with high affinity for Ag were evenly distributed
over the different molecular weight fractions. Particulate
Ag
was found associated mainly with a iron−manganese
oxyhydroxide/sulfide phase. The close relation
between
Ag and Fe in colloidal and particulate phases suggests
common
surface complexes, probably sulfhydryl groups. In
river
waters of Texas, 33−89% of the operationally defined
dissolved
(≤0.45 μm) Ag fraction was present in a large colloidal
form (0.1−0.45 μm). The high affinity of Ag for
suspended
particulates in river and estuarine water was reflected
by a high mean particle/water partition coefficient of log
K
d
= 5.0 ± 0.6 (based on filtration through a 0.45-μm
filter)
and 5.5 ± 0.5 (based on filtration through a 0.1 μm
filter).
Particle/water partition coefficients for the surface-adsorbed phase showed particle concentration effects,
which,
however, disappeared (log K
p1 = 5.0 ± 0.3)
when the
dissolved Ag data were corrected for the presence of a
colloidal fraction.
Meteotsunamis are atmospherically forced ocean waves with characteristics similar to seismic tsunamis. Several recent hazardous meteotsunamis resulted in damage and injuries along U.S. coastlines, such that the National Oceanic and Atmospheric Administration (NOAA) is investigating ways to detect and forecast meteotsunamis to provide advance warning. Better understanding meteotsunami occurrence along U.S. coastlines is a necessary step to pursue these objectives. Here a meteotsunami climatology of the U.S. East Coast is presented. The climatology relies on a wavelet analysis of 6-min water-level observations from 125 NOAA tide gauges from 1996 to 2017. A total of 548 meteotsunamis, or about per year, were identified and assessed using this approach along the U.S. East Coast. There were a total of 30 instances when gauges observed waves of more than 0.6 m, which is assumed to be a potentially impactful event, and several cases with wave heights more than 1 m. Tide gauges along the open coast observed the most frequent events, including more than five events per year at Atlantic City, New Jersey; Duck, North Carolina; and Myrtle Beach, South Carolina. The largest waves were observed by gauges in estuaries that amplified the meteotsunami signal, such as those in Providence, Rhode Island, and Port Canaveral, Florida. Seasonal trends indicate that meteotsunamis occur most frequently in the winter and summer months, especially July. This work supports future meteotsunami detection and warning capabilities at NOAA, including the development of an impact catalog to aid National Weather Service forecasters.
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