Total Suspended Concentration Research Articles

Sediment and Radioactivity Transport in the Bohai, Yellow, and East China Seas: A Modeling Study

This paper is concerned with the development of a radionuclide dispersion model for the nuclear power plants in the Bohai, Yellow, and East China seas (BYECS) characterized by high turbidity and multi-scale circulations, focusing on the comparison of dispersion processes of 137Cs depending upon, in particular, the suspended sediment concentration and erosion/sedimentation processes. The simulations were carried out using a multi-fraction sediment transport model embedded in the semi-implicit Eulerian–Lagrangian finite-element coupled wave-circulation model linked with the model of radionuclide transport, which describes the key radionuclide transfer processes in the system of water–multi-fraction sediments. In contrast to the Eulerian models used for hydrodynamics and sediment transport processes, the Lagrangian technique was applied to simulate the transport of radionuclides. The simulation results for total suspended concentration agreed with in situ measurements and the Geostationary Ocean Color Imager data. The results of the simulation of hypothetical releases of 137Cs from four nuclear power plants (NPPs) placed in BYECS essentially differ from the real release of activity in the Pacific Ocean shelf due to the Fukushima Daiichi accident, which took place at the same time and released activity that was similar. The total amount of bottom contamination of 137Cs in releases from the Sanmen, Hanbit, and Hongyanhe NPPs was about 40% of dissolved component, and the total amount of suspended component was about 20% of dissolved component, in contrast with the Fukushima Daiichi accident, where the particulate component was only 2%. The results demonstrate the importance of erosion processes in the budget of 137Cs in shallow areas around the Sanmen and Hanbit NPPs, where strong wind and tidal currents took place.

Variability of Intra-event Statistics for Multiple Fecal Indicator Bacteria in Urban Stormwater

Pathogens in surface waters continue to be a worldwide concern. The potential presence of pathogens is often identified through the use of fecal indicator bacteria such as fecal coliform, E. coli, and enterococci, each of which are still utilized worldwide depending on local regulations. Urban stormwater runoff has been shown to convey fecal indicator bacteria to surface waters; however, the fate and transport dynamics of these microbes in urban stormwater are not well established. This is particularly the case for intra-event (within event) processes. The intra-event characteristics of total suspended solids and three types of fecal indicator bacteria (FIB), fecal coliform, E. coli, and enterococci, were analysed for a watershed in Raleigh, NC, USA. FIB showed higher variability than TSS among intra-event characteristics such as normalized peak concentration, rate of change, and normalized concentration in the first 3 mm of rainfall (C3mm), but similar variability in concentrations throughout each storm. FIB intra-event statistics appear to be influenced by climate variables whereas total suspended sediments statistics are most influenced by hydrologic variables. Changes in intra-event total suspended concentrations were consistently well described by rainfall intensity, while FIB correlations with rainfall intensity were weaker and inconsistent between events. This study showed similar patterns of variability among the intra-event FIB statistics and comparable correlations to climatic and hydrologic variables between fecal coliform, E. coli, and enterococci. Thus, similar processes appear to influence the variability of all three indicator bacteria, suggesting that microbial models may be adaptable amongst various types of FIB.

Assessment of suspended solids in the Guadalquivir estuary using new DEIMOS-1 medium spatial resolution imagery

Measurements of Total Suspended concentrations (TSS) are critical for monitoring geomorphological processes as well as ensuring the “good status” of transitional and coastal waters. Here, we explore the potential of the new DEIMOS-1, multi-spectral, medium-resolution satellite sensor for quantifying TSS dynamics within the large, turbid Guadalquivir estuary (SW Iberian Peninsula). Eight scenes were atmospherically corrected using various image-based procedures (apparent reflectance; Dark Object Subtraction, DOS; and solar zenith angle approximation, COSTZ). In-situ measurements (100 to 1400mgL−1) from three campaigns coinciding (±15min) with satellite overpasses were used to assess the semi-analytical algorithm from Nechad et al. (2010) relating water-leaving reflectance (ρw) to TSS. All bands were very sensitive to TSS, however saturation of the visible wavelengths was observed at the highest sediment loads. The best correlation was obtained for the NIR band (755–906nm) using the simple band-reflectance model at the top of atmosphere reflectance (ρw(TOA)), TSS (mgL−1)=21428.77 ρw(TOA)/(1−ρw(TOA)/0.21)−346.17 (r2=0.864, p<0.001, εr=25.411%, n=53), which was used to generate maps. This approach revealed detailed spatio-temporal variability in sediment concentrations within the river plume, near to shore and far up the river channel. We demonstrate that DEIMOS-1 has a high capability as a valuable tool for the frequent, synoptic monitoring of water-quality parameters needed for the optimum management of coastal and transitional waters.

Floc fraction in the waters of the Po River prodelta

Three independent methods of estimating the proportion of suspended material packaged within flocs, termed the floc fraction (f), were employed using hydrographic and suspended sediment data, and core and tripod-based observation data collected from the waters and sediments of the Po River prodelta throughout 2001. Using a floc size versus settling velocity relationship established in this study, floc fraction estimates were derived as follows: (1) by calculation of floc concentration in in situ images versus total suspended concentration using knowledge of floc effective density via Stokes' approximation; (2) by parameterization of disaggregated inorganic grain size (DIGS) distributions of bottom sediments to infer floc fraction in suspension necessary to produce the observed flux to the seabed; and (3) by calculating a mean representative floc fraction estimate for the system derived from estimates of floc bulk density. Calculated estimates of floc fraction are near unity at the river mouth, with the bulk of floc deposition occurring by the 8m-isobath. Seaward and to the south of the river mouth, the suspension is not highly flocculated (f∼0.08). Subsequent transport and removal of deposited sediment from the prodelta, as suggested in previous study, is believed to occur within the bottom boundary layer.

Transdermal delivery of 5-fluorouracil through skin of hairless mice and humans in vitro: a comparison of the effect of formulations and a prodrug

A 2% commercial solution formulation of 5-fluorouracil (5-FU) was significantly better at delivering 5-FU than either a 1% or 5% solution. Among single component suspension formulations the highest transdermal delivery was obtained from the vehicle in which 5-FU was least soluble, isopropyl myristate (IPM), while changes in the total suspended concentration of 5-FU in propyleneglycol (PG) had no significant effect on transdermal delivery by those suspensions. A prodrug of 5-FU/IPM was significantly better at delivering 5-FU than any of the formulations. The trends in relative rates of delivery of 5-FU by the formulations and the prodrug were the same in skin of hairless mice and humans. The mouse skin was about ten times more permeable than the human skin. Second application studies to assess skin damage caused by the formulations also showed the same trend in skin of hairless mice and humans: all of the formulations caused some damage.

Sources of Suspended Matter in Waters of the Middle Atlantic Bight

ABSTRACT Suspended matter collected in the Middle Atlantic Bight (the coastal segment of the United States between Cape Cod and Cape Hatteras) in September 1969 was predominantly organic: an average of 80% combustible organic matter in surface waters and 40)% near bottom. Total suspended concentrations decreased between the inner shelf and the shelf break by an order of magnitude in both near-surface and near-bottom waters. The noncombustible (ash) fraction of the suspended matter decreased over the same distance by one order of magnitude in the near-bottom waters and two orders of magnitude in surface waters. Recently contributed river sediment is not a significant constituent of the suspended matter in the waters of the shelf, particularly the outer shelf. Most of the inorganic material in suspension represents resuspended bottom sediments (at least some of which are relict) whose suspended concentrations are increased noticeably by storms.