Metal Bioavailability in the Sava River Water

Metals present one of the major contamination problems for freshwater systems, such as the Sava River, due to their high toxicity, persistence, and tendency to accumulate in sediment and living organisms. The comprehensive assessment of the metal bioavailability in the Sava River encompassed the analyses of dissolved and DGT-labile metal species of nine metals (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn) in the river water, as well as the evaluation of the accumulation of five metals (Cd, Cu, Fe, Mn, and Zn) in three organs (liver, gills, and gastrointestinal tissue) of the bioindicator organism, fish species European chub (Squalius cephalus L.).This survey was conducted mainly during the year 2006, in two sampling campaigns, in April/May and September, as periods representative for chub spawning and post-spawning. Additionally, metal concentrations were determined in the intestinal parasites acanthocephalans, which are known for their high affinity for metal accumulation. Metallothionein concentrations were also determined in three chub organs, as a commonly applied biomarker of metal exposure. Based on the metal concentrations in the river water, the Sava River was defined as weakly contaminated and mainly comparable with unpolluted rivers, which enabled the analyses of physiological variability of metal and metallothionein concentrations in the chub organs, as well as the establishment of their constitutive levels

Seasonality in nutrient concentrations in Galveston Bay

337-362In order to investigate factors controlling nutrient cycling in the shallow and turbid coastal ecosystem of Galveston Bay, data from: (1) the Texas Water Commission (TWC) database 1980-1989, and (2) salinity transects in 1989 and 1993 are presented and analyzed. Statistical regression and time-series analysis were carried out on data acquired by TWC between 1980 and 1989, in an attempt to establish seasonality of nutrient and chlorophyll-a (chl.-a) concentrations in the bay and to determine factors which regulate these concentrations. A strong seasonality was found for phosphorus and chl. -a in the upper and mid-bay stations. A recurring maximum for phosphate occurred in September and a chl.-a maximum occurred regularly in March-April. It is hypothesized that benthic regeneration of phosphorus at the end of summer is responsible for the phosphate maximum. The inverse correlation of the partition coefficient (K-d) for phosphate with the concentration of suspended particulate matter (SPM), coupled to a strong enrichment of phosphate in suspended particles at low SPM concentrations, indicates additional control by geochemical and physical processes such as particle sorting and/or particle=colloid interactions. Nitrate is inversely correlated with salinity at the upper and mid-bay stations, indicating the Trinity River is a major source. Nutrient concentrations in the lower bay (East and West Bay stations) are considerably lower and less predictable, as they are not correlated with salinity or temperature. Data from the 1989 and 1993 transects confirm the yearly maximum in phosphate concentration in late summer months, with peak concentrations in the upper Trinity Bay. It is concluded that despite possible phosphate buffering by physical and geochemical mechanisms, relatively large concentration maxima recur regularly every year during the summer, possibly caused by a benthic source of phosphatehttp://gbic.tamug.edu/request.ht

Delivery of Trace Metals (Al, Fe, Mn, V, Co, Ni, Cu, Cd, Ag, Pb) from the Trinity River Watershed Towards the Ocean

pgs. 1-15The Trinity River (Texas, USA) contains in its watershed 23 different reservoir lakes, the largest one being Lake Livingston situated in the lower Trinity River watershed and two potentially polluting metroplexes, Dallas and Houston. In order to determine fluxes of nutrients and trace metals to Galveston Bay, a survey that included 24 discreet samples collected over a year and at various stages of discharge was carried out during 2000-2001. Geochemical (i.e., sorption by Fe oxyhydroxides), biological (i.e., seasonal uptake by sinking algae in Lake Livingston), and hydrological (i.e., dilution effects by increasing flow rates) controls were found to be mainly responsible for variations in dissolved trace metal concentrations rather than pollution sources. The Trinity River loads of suspended sediments and pollutant trace metals entering Galveston Bay at Anahuac were 96% of the pollutant trace metal load is lost to sediments.http://gbic.tamug.edu/request.ht

Environmental trends of contaminants from the Mississippi River Delta, Tampa Bay, and Galveston Bay sediment cores

ENVR-No abstract availablehttp://gbic.tamug.edu/request.ht

Biogeochemical behavior of organic carbon in the Trinity River downstream of a large reservoir lake in Texas, USA

-Dissolved and particulate organic carbon concentrations were measured and annual loads estimated for the Trinity River, the main freshwater input source to Galveston Bay, which lies on the upper Gulf coast of Texas, USA, during 2000-2001. This river drains the forested lowlands south of a relatively large reservoir lake, Lake Livingston. A weak relationship between dissolved organic carbon (DOC) and QTR indicated hydrologic control but separation of the data, based on individual discharge events, was necessary to improve interpretation. For instance, the first rain of the season resulted in only a modest increase in DOC concentrations and led to an inverse relationship with discharge, due to decreased lateral flow and increased infiltration of rainwater, with the lower flows being more efficient at DOC leaching from soils. In contrast, a long duration high discharge river crest event resulted in an opposite trend, i.e. a linear increase in DOC with increasing discharge rates. A short duration high discharge tropical storm showed reduced Trinity River DOC concentrations and the highest POC concentrations measured, likely resulting from the relatively short duration, and minimal contact time, of this event. In contrast to DOC, the concentrations of particulate organic carbon, POC (mg C l-1) were linearly correlated to suspended particulate matter (SPM) concentrations and accounted for between 10 and 12% of the total suspended load at low discharge but decreased to ~2% at high discharge. This suggests dilution by larger particles with a reduced organic carbon content, possibly silicate minerals, more readily resuspended at elevated levels of discharge. The annual total organic carbon (TOC) load to Galveston Bay, estimated from the slope of the daily load vs. discharge relationship, was 11.2 x 1010 g C and calculated export coefficients (g C m-2 year-1) were in good agreement with previous results. Using this relationship, accurate assessments of TOC flux inputs to Galveston Bay over the past quarter-century and in the future are possible by obtaining annual Trinity River discharge rates, which are readily available from the USGS. Comparing DOC riverine inputs to benthic sources in Trinity Bay, measured directly on the same day, indicates that the sediments contribute approximately 20% of total inputs of DOC to Trinity Bay. However, assuming a constant benthic source during low-flow conditions, which can occur for periods of up to 14 months in this region of Texas, benthic fluxes would account for >80% of the total inputs into Trinity Bay. At high levels of discharge, the Trinity River discharges ~1.0 x 109 g C day-1 and dominates DOC inputs to Trinity Ba

Sensitive determination of dissolved sulfide in estuarine water by solid-phase extraction and high-performance liquid chromatography of methylene blue

305-309A sensitive method involving solid-phase extraction and HPLC analysis of methylene blue has been developed to measure nanomolar levels of dissolved sulfide in oxic surface waters. The procedure included 1) a preconcentration step, in which methylene blue generated from sulfide reaction with n,n-dimethyl-p-phenylenediamine in acidic conditions in the presence of ferric ion was absorbed onto Waters tC(18) cartridge; and 2) a determination step, in which methylene blue was separated by HPLC in a gradient elution to minimize natural organic matter interference and detected by absorbance. The concentrations of the dissolved sulfide, quantified by standard addition, were about 2.1-4.7 nM in oxic surface waters from Galveston Bay, Texas. (C) 2000 Elsevier Science B.V. All rights reservedhttp://gbic.tamug.edu/request.ht

Cycling of high molecular weight dissolved organic matter in Galveston Bay and the Chesapeake Bay

-Conference papers indexhttp://gbic.tamug.edu/request.ht

Isotopic and elemental characterization of colloidal organic matter from the Chesapeake Bay and Galveston Bay

1-15In order to investigate sources and turnover rates of dissolved organic matter from Chesapeake Bay and Galveston Bay, colloidal organic matter (COM) was isolated using cross-flow ultrafiltration and subsequently characterized for its elemental (C, N, and S) and isotopic (C-13 and C-14) composition. Distributions of dissolved organic carbon (DOC) in Chesapeake Bay showed a non-systematic variation, while in Galveston Bay, a non-conservative behavior of DOC with source inputs in the low salinity region was observed. Results of size fractionation of total organic carbon (TOC) revealed that, on average, particulate organic carbon (POC) comprised similar to 12% and 39% of the TOC pool in Galveston Bay and the Chesapeake Bay, respectively. Colloidal organic carbon (COG) between 1 kDa and 0.2 mu m (COC1) constituted similar to 53% and 35%, respectively, with 6-7% of TOC in the HMW fraction (10 kDa to 0.2 mu m, COC10), and only similar to 34% and 25%, respectively, of the TOC in the <1 kDa dissolved fraction. Values of Delta(14)C and C/N ratios of COM, in general, decreased from river to coastal seawater whereas delta(13)C values increased with increasing salinity, indicating that organic carbon sources changed from more terrestrial components to phytoplankton-derived sources during estuarine mixing. The distinct isotopic signature and elemental composition of riverine and estuarine COM also suggest that most riverine HMW COM could be removed or decomposed rapidly within the estuary. The fact that values of C/N ratios increased from particulate to HMW to medium MW COM suggest that reactivities of organic matter decrease with reducing size. While Delta(14)C values of COM1 were generally equivalent to contemporary ages, they were consistently lower for the COM10. Lower delta(14)C values and lower C/N ratios in the COM10 than in the COM1 suggest that most of the estuarine HMW COM is from older and more proteinaceous sources within the estuaries. We hypothesize that resuspended sedimentary organic matter or recycled older DOM is likely the source for COM10. (C) 1997 Elsevier Science B.Vhttp://gbic.tamug.edu/request.ht

A seasonal survey of carbohydrates and uronic acids in the Trinity River, Texas

pgs. 463-474Due to their potential significance as indicators of ecological health, the biogeochemical cycling of carbohydrates and uronic acids was investigated in the Trinity River Texas, during 2000 2001. Concentrations of dissolved organic carbon (DOC), total carbohydrates (TCHO), polysaccharides (PCHO), monosaccharides (MCHO), uronic acids (URA), as well as of oxygen, suspended particulate matter, nutrients and trace metals (Cu, Pb, Cd) were assessed at various stages of discharge. TCHO/DOC ratios, as well as nutrient and hydrogen ion concentrations, were inversely related to temperature, which suggests that biological processes in Lake Livingston, the largest freshwater reservoir along the Trinity River, are not only regulating nutrient concentrations but also the preferential degradation of carbohydrates over that of bulk DOC. However, uronic acids were selectively preserved during this temperature controlled biological process, as is evident from the positive correlation of URA/TCHO ratios and temperature. Thus, uronic acids are more refractory compounds than bulk TCHO. Significant correlations between TCHO and dissolved Cu, Pb and Cd suggest that their pathways and cycles are linked through common sources or removal processes.http://gbic.tamug.edu/request.ht