Coupling PCSWMM and WASP to Evaluate Green Stormwater Infrastructure Impacts to Storm Sediment Loads in an Urban Watershed

We coupled rainfall–runoff and instream water quality models to evaluate total suspended solids (TSS) in Wissahickon Creek, a mid‐sized urban stream near Philadelphia, Pennsylvania. Using stormwater runoff and instream field data, we calibrated the model at a subdaily scale and focused on storm responses. We demonstrate that treating event mean concentrations as a calibration parameter rather than a fixed input can substantially improve model performance. Urban stormwater TSS concentrations vary widely in time and space and are difficult to represent simply. Suspended and deposited sediment pose independent stressors to stream biota and model results suggest that both currently impair stream health in Wissahickon Creek. Retrofitting existing detention basins to prioritize infiltration reduced instream TSS loads by 20%, suggesting that infiltration mitigates sediment more effectively than detention. Infiltrating stormwater from 30% of the watershed reduced instream TSS loads by 47% and cut the frequency of TSS exceeding 100 mg/L by half. Settled loads and the frequency of high TSS values were reduced by a smaller fraction than suspended loads and duration at high TSS values. A widely distributed network of infiltration‐focused projects is an effective stormwater management strategy to mitigate sediment stress. Coupling rainfall–runoff and water quality models is an important way to integrate watershed‐wide impacts and evaluate how management directly affects urban stream health.     

Sustainable wind‐driven bioventing at a petroleum hydrocarbon–impacted site

Bioventing—the injection of air into the vadose zone to increase microbial activity—is a commonly used, proven technology for remediating volatile organic compounds present in the vadose zone. Passive systems driven by wind or solar power are both more cost‐effective and sustainable than conventional systems. Such a passive system is being applied successfully to remediate a site impacted with total petroleum hydrocarbons (TPH) and benzene, toluene, ethylbenzene, and xylenes (BTEX) in soil. Bioventing technology was approved by the regulatory agency as an interim remedial action to remove chemicals of concern (COCs) in the vadose zone. A bioventing pilot study was conducted to evaluate the effectiveness of COC removal and collect parameters for full‐scale design and implementation. To evaluate the potential to use wind‐driven bioventing technology, two mobile weather stations were installed at the site and monitored for one month for a wind speed study. Based on the pilot‐test data and wind speed research, 12‐inch diameter funnel/vane 360‐degree wind collectors were designed as passive wind‐driven air‐injection devices and connected to existing monitoring wells. The measured air velocity ranged from 20 to 110 feet per minute during the start‐up and the first three months of operation and maintenance. Monitoring indicated a 20 percent oxygen delivery and greater than 90 percent reduction in COC concentrations, demonstrating a successful sustainable remediation with no power requirement and minimal operation and maintenance. © 2012 Wiley Periodicals, Inc.     

Toxaphene and other chlorinated compounds in human milk from northern and southern Canada: a comparison.

Human milk from residents of northern Canada (Keewatin) was compared to that in national surveys of southern Canada with respect to residues of toxaphene, PCBs, PCDD/PCDFs, chlordane, and several other persistent organic compounds. Concentrations of toxaphene were approximately ten-fold higher in specimens from Keewatin than from the south. Toxaphene concentrations in samples from the Great Lakes Basin collected in 1992 were not significantly (p < 0.05) different from those of the rest of Canada; however they were significantly (p < 0.05) lower than concentrations reported in a 1986 survey. Hexachlorobenzene, trans nonachlor and oxychlordane were three to five times higher in concentration in the Keewtin samples than in samples reported in the 1992 national survey. Total PCB congeners, DDTs, PCDD/PCDFs, and other chlorinated compounds were not significantly higher in northern samples.     

Fate of heavy metals and radioactive metals in gasification of sewage sludge

The fates of radioactive cadmium, strontium, cesium, cobalt, arsenic, mercury, zinc, and copper spiked into sewage sludge were determined when the sludge was gasified by a process that maximizes production of char from the sludge (ChemChar process). For the most part the metals were retained in the char product in the gasifier. Small, but measurable quantities of arsenic were mobilized by gasification and slightly more than 1% of the arsenic was detected in the effluent gas. Mercury was largely mobilized from the solids in the gasifier, but most of the mercury was retained in a filter composed of char prepared from the sludge. The small amounts of mercury leaving the gasification system were found to be associated with an aerosol product generated during gasification. The metals retained in the char product of gasification were only partially leachable with 50% concentrated nitric acid.     

Changes in ground water quality in an irrigated area of southern Alberta

Few studies have documented spatial and temporal variations in ground water quality in areas with high densities of animal farming operations (AFOs), or the long-term effects on surface-water quality. Changes in ground water quality were characterized in an irrigated area with a high density of AFOs in southern Alberta, Canada to evaluate the effect on ground water quality of manure application to fields. Fifty-five piezometers in the oxidized zone were sampled once or twice annually from 1995 to 2001, and temporal changes were analyzed using mixed model analysis. Average NO3- -N increased significantly from 12.5 to 17.4 mg L(-1) and average Cl- increased significantly from 19.4 to 34.4 mg L(-1) in piezometers installed in an unconfined sand aquifer at locations receiving fertilizer and manure. Compared with these manured locations, nitrate and chloride concentrations were significantly lower in shallow aquifer water in areas of pasture or native range, and concentrations did not change significantly with time. Nitrate and chloride concentrations in shallow ground water in fine-textured manured locations did not change significantly. Ground water below about 6 m in till and fine lacustrine sediments contains 18O signatures indicative of recharge under preirrigation or glacially influenced conditions, suggesting this ground water has a low vulnerability to agricultural contamination. Evaluations suggest that shallow ground water discharge will cause NO3- -N and Cl- in the Oldman River to increase by factors of at least 4.3 and 1.3, respectively, with more significant effects in smaller streams and under low-flow conditions.     

Co-management of Natural Resources: A Proposed Framework

Co-management acknowledges pragmatic developments and progression of institutional choice theories in natural resource management. This innovative concept embraces a pluralistic management approach based on the principle of subsidiarity and creates opportunities for the reconciliation of competitive property claims. This article reviews definitions of co-management, distinguishes it from other property rights regimes, and develops an organizational structure of the major elements involved. Synthesis of both experiences and literature leads to the development of a conceptual framework. Co-management is structured in terms of context, components, and linking mechanisms. In concert, these elements offer insight into the practice of co-management, address the shortcomings of institutional theories, and respond to critical issues raised in related literature. The framework contributes to natural resource management by acting as a means of identification and evaluation for such arrangements, as well as a systematic guide for future inquiries.     

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.