Levels of dioxins and dibenzofurans in breast milk of women residing in two cities in the Irkutsk Region of Russian Siberia compared with American levels

The presence of dioxins, dibenzofurans, and polychlorinated biphenyls (PCBs) in human tissue, food, and environmental samples from Russia has been monitored since 1988 as part of a research collaboration between a number of countries including Finland, the United States, Germany, the former Soviet Union, and Canada. Although elevated TCDD and PnCDD levels have previously been found in blood of male and female Russian chemical manufacturing workers and in their children, dioxin levels in the general population have usually been found to be lower than in Americans and Europeans. This study continues earlier work in the Irkutsk region of Russian Siberia, where we report levels of dioxin, dibenzofurans, and PCBs in human milk samples taken from general population women living in the industrialized cities of Angarsk and Usolye-Sibirskoye, near Lake Baikal. Total polychlorinated dibenzo-p-dioxin (PCDD) toxic equivalents (TEQs) compared in this paper for the industrialized regions of Siberia, Ukraine, and the US are similar, ranging from 6.1 to 7 parts per trillion (ppt). Recent 1998 milk samples from Angarsk and Usolye-Sibirskoye have total mean polychlorinated dibenzofuran (PCDF) TEQs of 10 and 21.7 ppt, respectively, with the other industrialized countries ranging from 2.3 to 6.7 ppt. Although dioxin-like PCBs were not measured for the city of Usolye-Sibirskoye (1998), total mean PCDD/F TEQ from Angarsk and Usolye-Sibirskoye (1998) were the two highest levels in this study, with 26.9 and 28.5 ppt, respectively, followed by 1993-1994 Ukraine samples with 24 ppt, 1989 Siberian samples with 13.6 ppt, and 1996 USA with 11.4 ppt total TEQ. In this study, higher levels of dioxins are noted in milk from Angarsk and Usolye-Sibirskoye than found in earlier Russian studies, with mean levels also exceeding 1996 and 1999 US breast milk dioxin levels.     

Virus transport in physically and geochemically heterogeneous subsurface porous media

A two-dimensional model for virus transport in physically and geochemically heterogeneous subsurface porous media is presented. The model involves solution of the advection-dispersion equation, which additionally considers virus inactivation in the solution, as well as virus removal at the solid matrix surface due to attachment (deposition), release, and inactivation. Two surface inactivation models for the fate of attached inactive viruses and their subsequent role on virus attachment and release were considered. Geochemical heterogeneity, portrayed as patches of positively charged metal oxyhydroxide coatings on collector grain surfaces, and physical heterogeneity, portrayed as spatial variability of hydraulic conductivity, were incorporated in the model. Both layered and randomly (log-normally) distributed physical and geochemical heterogeneities were considered. The upstream weighted multiple cell balance method was employed to numerically solve the governing equations of groundwater flow and virus transport. Model predictions show that the presence of subsurface layered geochemical and physical heterogeneity results in preferential flow paths and thus significantly affect virus mobility. Random distributions of physical and geochemical heterogeneity have also notable influence on the virus transport behavior. While the solution inactivation rate was found to significantly influence the virus transport behavior, surface inactivation under realistic field conditions has probably a negligible influence on the overall virus transport. It was further demonstrated that large virus release rates result in extended periods of virus breakthrough over significant distances downstream from the injection sites. This behavior suggests that simpler models that account for virus adsorption through a retardation factor may yield a misleading assessment of virus transport in "hydrogeologically sensitive" subsurface environments.     

Transuranic biokinetic parameters for marine invertebrates--a review

A catalogue of biokinetic parameters for the transuranic elements plutonium, americium, curium, neptunium, and californium in marine invertebrates is presented. The parameters considered are: the seawater-animal concentration factor (CF); the sediment-animal concentration ratio (CR); transuranic assimilation efficiency; transuranic tissue distribution and transuranic elimination rates. With respect to the seawater-animal CF, authors differ considerably on how they define this parameter and a seven-point reporting system is suggested. Transuranic uptake from sediment by animals is characterised by low CRs. The assimilation efficiencies of transuranic elements in marine invertebrates are high compared to vertebrates and mammals in general and the distribution of transuranics within the body tissue of an animal is dependent on the uptake path. The elimination of transuranics from most species examined conformed to a standard biphasic exponential model though some examples with three elimination phases were identified.     

Contrasting nitrate adsorption in Andisols of two coffee plantations in Costa Rica

Fertilizer use in coffee plantations is a suspected cause of rising ground water nitrate concentrations in the ground water-dependent Central Valley of Costa Rica. Nitrate adsorption was evaluated beneath two coffee (Coffea arabica L.) plantations in the Central Valley. Previous work at one site had identified unsaturated zone nitrate retardation relative to a tritium tracer. Differences in nitrate adsorption were assessed in cores to 4 m depth in Andisols at this and one other plantation using differences in KCl- and water-extractable nitrate as an index. Significant adsorption was confirmed at the site of the previous tracer test, but not at the second site. Anion exchange capacity, X-ray diffraction data, extractable Al and Si, and soil pH in NaF corroborated that differences in adsorption characteristics were related to subtle differences in clay mineralogy. Soils at the site with significant nitrate adsorption showed an Al-rich allophane clay content compared with a more weathered, Si-rich allophane and halloysite clay mineral content at the site with negligible adsorption. At the site with significant nitrate adsorption, nitrate occupied less than 10% of the total anion adsorption capacity, suggesting that adsorption may provide long-term potential for mitigation or delay of nitrate leaching. Evaluation of nitrate sorption potential of soil at local and landscape scales would be useful in development of nitrogen management practices to reduce nitrate leaching to ground water.     

Issues related to solution chemistry in mercury sampling impingers

Analysis of Hg speciation in combustion flue gases is often accomplished in standardized sampling trains in which the sample is passed sequentially through a series of aqueous solutions to capture and separate oxidized Hg (Hg2+) and elemental Hg (Hg0). Such methods include the Ontario Hydro (OH) and the Alkaline Mercury Speciation (AMS) methods, which were investigated in the laboratory to determine whether the presence of Cl2 and other common flue gas species can bias the partitioning of Hg0 to front impingers intended to isolate Hg2+ species. Using only a single impinger to represent the front three impingers for each method, it was found that as little as 1-ppm Cl2 in a simulated flue gas mixture led to a bias of approximately 10-20% of Hg0 misreported as Hg2+ for both the OH and the AMS methods. Experiments using 100-ppm Cl2 led to a similar bias in the OH method, but to a 30-60% bias in the AMS method. These false readings are shown to be due to liquid-phase chemistry in the impinger solutions, and not necessarily to the gas-phase reactions between Cl2 and Hg as previously proposed. The pertinent solution chemistry causing the interference involves the hypochlorite ion (OCl-), which oxidizes Hg0 to soluble Hg2+. Addition of sodium thiosulfate (Na2S2O3) to the front impinger solutions eliminates this false positive measurement of Hg2+ by selectively reacting with the OCl- ion. In general, the presence of SO2 also mitigates this interference in the same way, and so this bias is not likely to be a factor for Hg speciation measurements from actual coal combustion flue gases. It might, however, be a problem for those few combustor flue gas measurements and research studies where Cl2 is present without appreciable amounts of SO2.     

Technetium-99 in the Irish marine environment

Technetium-99 activity concentrations in seawater and biota from Irish coastal waters are presented. Time series measurements of 99Tc in seawater and Fucus vesiculosus from the western Irish Sea show that activity concentrations have increased in line with the increase in discharges of 99Tc from Sellafield. The peak in activity concentrations in both seawater and Fucus vesiculosus occurred in 1997 approximately two years after the peak in 99Tc discharges. The highest activity concentration recorded in Fucus vesiculosus showed a 29-fold increase over the mean concentration for the period 1988-1993. Technetium-99 activity concentrations were measured in fish, lobsters, prawns, mussels and oysters landed at major fishing ports on the east and northeast coasts of Ireland between 1996 and 1998. Concentration factors for 99Tc in the brown seaweed Fucus vesiculosus and certain species of fish, crustaceans and molluscs from the Irish Sea were estimated. In general, these concentration factors were higher than those in the literature which were derived from laboratory studies, but agreed well with values which were based on field studies. The mean committed effective doses to Irish typical and heavy seafood consumers due to 99Tc in the period 1996-1998 were 0.061 and 0.24 microSv, respectively.     

MORPHOLOGIC RESPONSE OF SUBALPINE STREAMS TO TRANSBASIN FLOW DIVERSION1

ABSTRACT: Flow has been diverted from Rocky Mountain streams for many years with little documentation of the impacts on physical form and biological function of the losing stream system. This study addresses whether differences in form can be detected in subalpine step-pool, plane bed, or pool-riffle channels and linked to changes in flow regime from diversion. Total annual discharge was reduced between 20 and 60 percent and average annual peak flow was reduced up to 45 percent in the subalpine systems assessed; channels were diverted between 20 and 100 years. Expected impacts include reduced conveyance and changes in vegetation growth patterns because formerly active surfaces are colonized by riparian species, effectuating shrinking channel capacity. In this study, reduced channel width is used as an indicator of morphologic response. Observed reductions in width, ranging from 35 to 50 percent at some sites, resulted not only from vegetation invasion of stable surfaces but also from the development of an inset beside former cut banks. This observation, however, was restricted to wider pool-riffle channels with gravel bars. Outside of these areas, morphologic changes were either subtle or absent. The absence of widespread response is attributed primarily to periodic “flooding” of the diverted channel. During wetter-than-average years when excess water is available, minimal flow is diverted and the hydrograph resembles a free-flowing regime. The release of high flow to the natural channel potentially offsets changes in form incurred during “dry” periods. The stable nature and structure of subalpine channels also contributes to the absence of reduced capacity.     

WATER CONSTRAINTS ON EMERGING ENERGY PRODUCTION1

ABSTRACT: A comprehensive nationwide recognizance-level assessment of water needs for energy development over the 1985 to 2000 time frame and options for overcoming any actual or potential water supply problems are summarized. Water requirements for energy production and other uses are totaled for each geographic region of the United States and compared with available stream flow to identify regions with potentially inadequate water supplies to meet expanding energy needs. Water quality impacts and water-related institutional factors affecting energy development are also considered. It is concluded that, if proper planning measures are not initiated, water demands for energy production will not be satisfied by the year 2000, particularly in those areas with known fossil energy resources. No unmanageable water quality problems are foreseen, and water-related institutional factors will primarily delay rather than exclud energy development.     

Phosphorus runoff: effect of tillage and soil phosphorus levels

Continued inputs of fertilizer and manure in excess of crop requirements have led to a build-up of soil phosphorus (P) levels and increased P runoff from agricultural soils. The objectives of this study were to determine the effects of two tillage practices (no-till and chisel plow) and a range of soil P levels on the concentration and loads of dissolved reactive phosphorus (DRP), algal-available phosphorus (AAP), and total phosphorus (TP) losses in runoff, and to evaluate the P loss immediately following tillage in the fall, and after six months, in the spring. Rain simulations were conducted on a Typic Argiudoll under a corn (Zea mays L.)-soybean [Glycine max (L.) Merr.] rotation. Elapsed time after tillage (fall vs. spring) was not related to any form of P in runoff. No-till runoff averaged 0.40 mg L(-1) and 0.05 kg ha(-1) DRP and chisel-plow plots averaged 0.24 mg L(-1) and 0.02 kg ha(-1) DRP concentration and loads, respectively. The relationship between DRP and Bray P1 extraction values was approximated by a logistic function (S-shaped curve) for no-till plots and by a linear function for tilled plots. No significant differences were observed between tillage systems for TP and AAP in runoff. Bray P1 soil extraction values and sediment concentration in runoff were significantly related to the concentrations and amounts of AAP and TP in runoff. These results suggest that soil Bray P1 extraction values and runoff sediment concentration are two easily measured variables for adequate prediction of P runoff from agricultural fields.     

Analysis of climate trends in North Carolina (1949-1998)

North Carolina has one of the most complex climates in the United States (U.S.). Analysis of the climate in this state is critical for agricultural and planning purposes. Climate patterns and trends in North Carolina are analyzed for the period 1949-1998. Precipitation, minimum temperature, and maximum temperature are analyzed on seasonal and annual time scales using data collected from the National Weather Service Cooperative Observer Network. Additionally, changes in patterns of occurrence of the last spring freeze and first fall freeze are investigated. Linear time series slopes are analyzed to investigate the spatial and temporal trends of climate variability in North Carolina. Spatial analysis of climate variability across North Carolina is performed using a geographic information system.While most trends are local in nature, there are general statewide patterns. Precipitation in North Carolina has increased over the past 50 years during the fall and winter seasons, but decreased during the summer. Temperatures during the last 10 years are warmer than average, but are not warmer than those experienced during the 1950s. The warm season has become longer, as measured by the dates of the last spring freeze and first fall freeze. Generally, the last 10 years were the wettest of the study period.These conclusions are consistent with earlier studies that show that the difference between the maximum and minimum temperatures is decreasing, possibly due to increased cloud cover and precipitation. Similarly, these results show that temperature patterns are in phase with the North Atlantic Oscillation and precipitation patterns appear to be correlated with the Pacific Decadal Oscillation.