Distribution of polychlorinated biphenyls in the Fort Edward,New York,water system

Levels of polychlorinated biphenyls (PCBs) have been determined in the water, in the soils and sediments, and in the biota of a small upstate New York public water supply system, which is near the heavily polluted section of the Hudson River and a disposal site for PCB-containing waste. The impounded water exhibits a significant and relatively uniform level of Aroclor 1016, whereas the ground and surface waters supplying the reservoir do not. Rainfall, which exhibits a high level of Aroclor 1016, constitutes a small but significant source of PCB input. Soil and sediment samples exhibit significant median levels of both Aroclor 1016 and Aroclor 1254, but the local concentrations vary widely. The biota exhibit much higher PCB levels than the water or sediments, and show a strong preference for Aroclor 1254. The PCB levels in the macroinvertebrates are particularly high, suggesting that these organisms may provide a useful indicator for monitoring PCB contamination in aquatic systems. Risk assessment indicates that the lifetime incremental risk of cancer associated with the drinking water is below 10^–6. Management of such low levels of PCB contamination is best achieved by reducing the input of PCBs.     

Characterizing Runoff and Water Yield for Headwater Catchments in the Southern Sierra Nevada

In a Mediterranean climate where much of the precipitation falls during winter, snowpacks serve as the primary source of dry season runoff. Increased warming has led to significant changes in hydrology of the western United States. An important question in this context is how to best manage forested catchments for water and other ecosystem services? Answering this basic question requires detailed understanding of hydrologic functioning of these catchments. Here, we depict the differences in hydrologic response of 10 catchments. Size of the study catchments ranges from 50 to 475 ha, and they span between 1,782 and 2,373 m elevation in the rain‐snow transitional zone. Mean annual streamflow ranged from 281 to 408 mm in the low elevation Providence and 436 to 656 mm in the high elevation Bull catchments, resulting in a 49 mm streamflow increase per 100 m (R² = 0.79) elevation gain, despite similar precipitation across the 10 catchments. Although high elevation Bull catchments received significantly more precipitation as snow and thus experienced a delayed melt, this increase in streamflow with elevation was mainly due to a reduction in evapotranspiration (ET) with elevation (45 mm/100 m, R² = 0.65). The reduction in ET was attributed to decline in vegetation density, growing season, and atmospheric demand with increasing elevation. These findings suggest changes in streamflow in response to climate warming may likely depend on how vegetation responds to those changes in climate.     

Meadow Restoration Increases Baseflow and Groundwater Storage in the Sierra Nevada Mountains of California

In mountains of the western United States, channel incision has drawn down the water table across thousands of square kilometers of meadow floodplain. Here climate change is resulting in earlier melt and reduced snowpack and water resource managers are responding by investing in meadow restoration to increase springtime storage and summer flows. The record‐setting California drought (2012–2015) provided an opportunity to evaluate this strategy under the warmer and drier conditions expected to impact mountain water supplies. In 2012, 0.1 km² of meadow floodplain was reconnected by filling an incised channel through Indian Valley in the central Sierra Nevada Mountains of California. Despite sustained drought conditions after restoration, summer baseflow from the meadow increased 5–12 times. Before restoration, the total summer outflow from the meadow was 5% more than the total summer inflow. After restoration, total summer outflow from the meadow was between 35% and 95% more than total summer inflow. In the worst year of the drought (2015), when inflow to the meadow ceased for at least one month, summer baseflow was at least five times greater than before restoration. Groundwater levels also rose at four out of five sites near the stream channel. Filling the incised channel and reconnecting the meadow floodplain increased water availability and streamflow, despite unprecedented drought conditions.     

Activated carbon immobilizes residual polychlorinated biphenyls in weathered contaminated soil

Activated carbon (AC) has recently been shown to be effective in sequestering persistent organic pollutants (POPs) from aquatic sediments. Most studies have demonstrated significant reductions of POP concentrations in water and in aquatic organisms; however, limited data exist on the possibility of using AC to immobilize remaining POPs at terrestrial contaminated sites. Under greenhouse conditions, pumpkin ssp cv. Howden) were grown, and red wiggler worms () were exposed to an industrial contaminated soil containing a mixture of polychlorinated biphenyls (PCBs), i.e., Aroclors 1254 and 1260) treated with one of four concentrations of AC (0.2, 0.8, 3.1, and 12.5%) for 2 mo. The addition of AC to contaminated soils virtually eliminated the bioavailability of PCBs to the plant and invertebrate species. There were reductions in PCB concentrations of more than 67% in ssp and 95% in . These data suggest that AC could be included as part of comprehensive site closure strategy at PCB-contaminated sites.     

Impacts of hydroelectric development on riparian vegetation in the Sierra Nevada region,California, USA

Fourteen streams in the Sierra Nevada in the USA were sampled to determine whether diversions of streamflow for hydroelectric development had caused significant changes in riparian vegetation. Several streams showed significant differences in vegetation cover, community composition, or community structure between pairs of diverted and undiverted reaches. On some streams, environmental conditions rather than streamflow diversions may have been responsible for vegetation differences. Streams in the Sierra Nevada respond individualistically to diversions. Prediction of vegetation responses must take into consideration environmental characteristics of specific stream reaches.     

Review of information on pesticide residues in the Canadian environment

Summary Pesticide residues in soil, water, food, wildlife and other media have been analysed in several monitoring studies. The purpose was to establish the distribution of these residues across a defined area, ascertain their trend over a specific period and use the results to assess environmental compliance and safety. In the present review the availability of information on pesticide residues in various Canadian environmental components was sought. With the possible exception of localized pesticide contamination of some private water supply wells, ground and surface water, most analyses revealed concentrations below guideline limits. Only a few cases were reported of mishandling, misuse and poisoning from pesticides. Continuing surveillance programmes and in-depth and well-organized monitoring studies, with special focus on areas that are vulnerable to contamination, by both provincial and federal governments, are largely responsible for the encouraging results. This experience in the control of pesticide use and monitoring of residues in the environment should be of particular interest in developing countries.Dr A.Y. Sangodoyin is a senior lecturer in the Department of Agricultural Engineering at the University of Ibadan. He was recently involved in a study visit to the University of Alberta, Edmonton, Alberta, Canada T6G 2G7, where his co-author Dr D.W. Smith is a member of staff in the Department of Civil-Engineering.     

Use of fertilization and grazing exclusion in mitigating lost meadow production in the Sierra Nevada,California, USA

The effects of a single fertilizer treatment (ammonium phosphate at 841 kg/ha, plus dolomite at 336 kg/ha) and cattle exclusion were studied in two meadows in the Sierra Nevada of California in the USA. Grazing exclusion had no effects on soil bulk density during the three years of the study. Fertilization had no effect on total soil nitrogen, soil pH, or crude protein concentrations in graminoids or forbs. Saturated soils and the development of anaerobic conditions close to the surface may have led to denitrification and the loss of usable nitrogen. Fertilization did result in short-term (one- to two-year) increases in available soild phosphorus in the drier of the two meadows, and in total phosphorus concentrations in graminoids and forbs, which were otherwise generally deficient in phosphorus. Few changes in plant species composition or production were detected, although a combination of fertilization and grazing exclusion increased forb production in the drier meadow. Based on our initial results, fertilization with phosphorus was the recommended treatment for meadow improvement projects in the central Sierra Nevada.     

Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation1

Young, Charles A., Marisa I. Escobar‐Arias, Martha Fernandes, Brian Joyce, Michael Kiparsky, Jeffrey F. Mount, Vishal K. Mehta, David Purkey, Joshua H. Viers, and David Yates, 2009. Modeling the Hydrology of Climate Change in California’s Sierra Nevada for Subwatershed Scale Adaptation. Journal of the American Water Resources Association (JAWRA) 45(6):1409‐1423. Abstract: The rainfall‐runoff model presented in this study represents the hydrology of 15 major watersheds of the Sierra Nevada in California as the backbone of a planning tool for water resources analysis including climate change studies. Our model implementation documents potential changes in hydrologic metrics such as snowpack and the initiation of snowmelt at a finer resolution than previous studies, in accordance with the needs of watershed‐level planning decisions. Calibration was performed with a sequence of steps focusing sequentially on parameters of land cover, snow accumulation and melt, and water capacity and hydraulic conductivity of soil horizons. An assessment of the calibrated streamflows using goodness of fit statistics indicate that the model robustly represents major features of weekly average flows of the historical 1980‐2001 time series. Runs of the model for climate warming scenarios with fixed increases of 2°C, 4°C, and 6°C for the spatial domain were used to analyze changes in snow accumulation and runoff timing. The results indicated a reduction in snowmelt volume that was largest in the 1,750‐2,750 m elevation range. In addition, the runoff center of mass shifted to earlier dates and this shift was non‐uniformly distributed throughout the Sierra Nevada. Because the hydrologic model presented here is nested within a water resources planning system, future research can focus on the management and adaptation of the water resources system in the context of climate change.     

Snowmelt Runoff and Water Yield Along Elevation and Temperature Gradients in California’s Southern Sierra Nevada1

Hunsaker, Carolyn T., Thomas W. Whitaker, and Roger C. Bales, 2012. Snowmelt Runoff and Water Yield Along Elevation and Temperature Gradients in California’s Southern Sierra Nevada. Journal of the American Water Resources Association (JAWRA) 48(4): 667‐678. DOI: 10.1111/j.1752‐1688.2012.00641.x Abstract: Differences in hydrologic response across the rain‐snow transition in the southern Sierra Nevada were studied in eight headwater catchments – the Kings River Experimental Watersheds – using continuous precipitation, snowpack, and streamflow measurements. The annual runoff ratio (discharge divided by precipitation) increased about 0.1 per 300 m of mean catchment elevation over the range 1,800‐2,400 m. Higher‐elevation catchments have lower vegetation density, shallow soils with rapid permeability, and a shorter growing season when compared with those at lower elevations. Average annual temperatures ranged from 6.8°C at 2,400 m to 8.6 at 1,950 m elevation, with annual precipitation being 75‐95% snow at the highest elevations vs. 20‐50% at the lowest. Peak discharge lagged peak snow accumulation on the order of 60 days at the higher elevations and 20 to 30 days at the lower elevations. Snowmelt dominated the daily streamflow cycle over a period of about 30 days in higher elevation catchments, followed by a 15‐day transition to evapotranspiration dominating the daily streamflow cycle. Discharge from lower elevation catchments was rainfall dominated in spring, with the transition to evapotranspiration dominance being less distinct. Climate warming that results in a longer growing season and a shift from snow to rain would result in earlier runoff and a lower runoff ratio.     

Biocontainment of polychlorinated biphenyls (PCBs) on flat concrete surfaces by microbial carbonate precipitation

In this study, a biosealant obtained from microbial carbonate precipitation (MCP) was evaluated as an alternative to an epoxy-coating system. A bacterium Sporosarcina pasteurii strain ATCC 11859, which metabolizes urea and precipitates calcite in a calcium-rich environment, was used in this study to generate the biosealant on a PCB-contaminated concrete surface. Concrete cylinders measuring 3 in (76.2 mm) by 6 in (152.4 mm) were made in accordance with ASTM C33 and C192 and used for this purpose. The PCB, urea, Ca(2+), and bacterial cell concentrations were set at 10 ppm, 666 mM, 250 mM, and about 2.1 × 10(8) cells mL(-1), respectively. The results indicate that the biosealed surfaces reduced water permeability by 1-5 orders of magnitude, and had a high resistance to carbonation. Since the MCP biosealant is thermally stable under temperatures of up to 840 °C, the high temperatures that normally exist in the surrounding equipment, which may contain PCB-based fluids, have no effect on the biosealed surfaces. Consequently, there is greater potential to obtain a stronger, coherent, and durable surface by MCP. No measurable amount of PCBs was detected in the permeating water, indicating that the leaching water, if any, will have a minimum impact on the surrounding environment.     

Associations between stream valley geomorphology and riparian vegetation as a basis for landscape analysis in the eastern Sierra Nevada,California, USA

Ten streams in the eastern Sierra Nevada, California, were classified into six geomorphic valley types and sampled to determine environmental and riparian vegetation conditions. The geomorphic valley types were relatively uniform geologically and hydrologically, collectively representing the range of stream environments in the region. There were significant associations between the geomorphic valley types and riparian community composition. These geomorphic-vegetation units are landscape elements which comprise the riparian ecosystems in the region. They differ in their ecological charactersitics and sensitivity to management. The system of landscape elements can be used to classify streams for the purposes of resource inventory, detailed ecological studies, and impact prediction.     

Riparian vegetation instream flow requirements: A case study from a diverted stream in the Eastern Sierra Nevada,California, USA

A methodology is described that allows determination of instream flow requirements for maintenance of riparian trees. Tree-ring data revealed strong relationships between tree growth and stream flow volume for riparian species at Rush Creek, an alluvial stream within an arid setting; these relationships allowed development of models that predict growth rates from hydrologic variables. The models can be used to assess instream flow requirements under the assumption that certain levels of growth are necessary to maintain the population. There is a critical need for development and use of instream flow methodologies for riparian vegetation, since present methodologies focus on needs of aquatic animals (e.g., fish) and may underestimate needs of the entire riparian ecosystem.     

Projections of 21st Century Sierra Nevada Local Hydrologic Flow Components Using an Ensemble of General Circulation Models1

Abstract: Sierra Nevada snowmelt and runoff is a key source of water for many of California’s 38 million residents and nearly the entire population of western Nevada. The purpose of this study was to assess the impacts of expected 21st Century climatic changes in the Sierra Nevada at the subwatershed scale, for all hydrologic flow components, and for a suite of 16 General Circulation Models (GCMs) with two emission scenarios. The Soil and Water Assessment Tool (SWAT) was calibrated and validated at 35 unimpaired streamflow sites. Results show that temperatures are projected to increase throughout the Sierra Nevada, whereas precipitation projections vary between GCMs. These climatic changes drive a decrease in average annual streamflow and an advance of snowmelt and runoff by several weeks. The largest streamflow reductions were found in the mid‐range elevations due to less snow accumulation, whereas the higher elevation watersheds were more resilient due to colder temperatures. Simulation results showed that decreases in snowmelt affects not only streamflow, but evapotranspiration, surface, and subsurface flows, such that less water is available in spring and summer, thus potentially affecting aquatic and terrestrial ecosystems. Declining spring and summer flows did not equally affect all subwatersheds in the region, and the subwatershed perspective allowed for identification for the most sensitive basins throughout the Sierra Nevada.     

Analyzing social perception as a key factor in the management of protected areas: the case of the Sierra Nevada Protected Area (S Spain)

Protected areas cannot be considered as elements isolated from the human groups that inhabit them. Consideration of the social factor is fundamental to guarantee the success of any management model. In this sense, analyzing the perception of people who live in protected areas can be a key tool for the formulation of proposals for improving the existing models. This article explores perceptions of local residents in the Sierra Nevada Protected Area in Southern Spain and identifies the socio-demographic factors that affect these perceptions. The main objective is to generate relevant data for the protected area management team. The recommendations we can offer entail a review of the communication plan and participatory strategy considering social differences in perceptions of the local population.     

Summary of well water sampling in California to detect pesticide residues resulting from nonpoint-source applications

This report summarizes well sampling protocols, data collection procedures, and analytical results for the presence of pesticides in ground water developed by the California Department of Pesticide Regulation (DPR). Specific well sampling protocols were developed to meet regulatory mandates of the Pesticide Contamination Prevention Act (PCPA) of 1986 and to provide further understanding of the agronomic, chemical, and geographic factors that contribute to movement of residues to ground water. The well sampling data have formed the basis for the DPR's regulatory decisions. For example, a sampling protocol, the Four-Section Survey, was developed to determine if reported detections were caused by nonpoint-source agricultural applications, a determination that can initiate formal review and subsequent regulation of a pesticide. Selection of sampling sites, which are primarily rural domestic wells, was initially based on pesticide use and cropping patterns. Recently, soil and depth-to-ground water data have been added to identify areas where a higher frequency of detection is expected. In accordance with the PCPA, the DPR maintains a database for all pesticide well sampling in California with submission required by all state agencies and with invitations for submission extended to all local and federal agencies or other entities. To date, residues for 16 active ingredients and breakdown products have been detected in California ground water as a result of legal agricultural use. Regulations have been adopted for all detected parent active ingredients, and they have been developed regardless of the level of detection.     

Basic hydrologic studies for assessing impacts of flow diversions on riparian vegetation: Examples from streams of the eastern Sierra Nevada,California, USA

As the number of proposals to divert streamflow for power production has increased in recent years, interest has grown in predicting the impacts of flow reductions on riparian vegetation. Because the extent and density of riparian vegetation depend largely on local geomorphic and hydrologic setting, site-specific geomorphic and hydrologic information is needed. This article describes methods for collecting relevant hydrologic data, and reports the results of such studies on seven stream reaches proposed for hydroelectric development in the eastern Sierra Nevada, California, USA. The methods described are: (a) preparing geomorphic maps from aerial photographs, (b) using well level records to evaluate the influence of streamflow on the riparian water table, (c) taking synoptic flow measurements to identify gaining and losing reaches, and (d) analyzing flow records from an upstream-downstream pair of gages to document seasonal variations in downstream flow losses. In the eastern Sierra Nevada, the geomorphic influences on hydrology and riparian vegetation were pronounced. For example, in a large, U-shaped glacial valley, the width of the riparian strip was highly variable along the study reach and was related to geomorphic controls, whereas the study reaches on alluvial fan deposits had relatively uniform geomorphology and riparian strip width. Flow losses of 20% were typical over reaches on alluvial fans. In a mountain valley, however, one stream gained up to 275% from geomorphically controlled groundwater contributions.     

Forest fertilization with wood ash: effect on the distribution and storage of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs)

Before wood ash can be safely used as a fertilizer in forests, possible negative effects such as input of organic contaminants or remobilization of contaminants already stored in the soil must be investigated. The objective of this study was to examine the effects of wood ash application on concentrations, storage, and distribution of polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs) in a Swiss forest soil. In May 1998, we added 8 Mg wood ash ha(-1) to a forest soil. We determined 20 PAHs and 14 PCBs in the organic layer, in the bulk mineral soil, and in soil material taken from preferential flow paths and from the matrix before and after the wood ash application. In the control plots, the concentrations of PAHs in the organic layer indicated moderate pollution (sum of 20 PAHs: 0.8-1.6 mg kg(-1)), but sum of PCB concentrations was high (21-48 microLg kg(-1)). The wood ash had high concentrations of PAHs (sum of 20 PAHs: 16.8 mg kg(-1)), but low concentrations of PCBs (sum of 14 PCBs: 3.4 microg kg(-1)). The wood ash application increased the PAH concentrations in the organic horizons up to sixfold. In contrast, PCB concentrations did not change in the Oa horizon and decreased up to one third in the Oi and Oe horizons. The decrease was probably caused by the mobilization of stored PCBs because of the high pH of the wood ash. This probably results in a higher mobility of dissolved organic matter, acting as PCB carrier. In the mineral soil, the preferential flow paths of the A horizon contained more PAHs and PCBs (+20 +/- 15% and +43 +/- 60%, respectively) than the matrix. This was particularly true for higher molecular weight compounds (molecular weight > 200 g mol(-1)). Below 50 cm depth, concentrations of PAHs and PCBs were smaller in the preferential flow paths, suggesting that in deeper depths, processes acting as sinks dominated over inputs in the preferential flow paths.     

Behavior of pesticide residues in agricultural soil and adjacent River Kuywa sediment and water samples from Nzoia sugarcane belt in Kenya

An inventory survey conducted to determine pesticide usage in a sub-catchment of the Nzoia sugarcane belt found a variety of pesticides used in the sub-catchment, which are reported in this paper. Analysis of soil samples from seven fallow experimental field plots left uncultivated for various periods from 3 to 96?months after cultivation with pesticide application indicated persistence of high concentrations of pesticide residues in the soil, with estimated soil half-lives (in years) ranging from 0.72 to 57.75 for organochlorines and from 1.13 to 8.25 for herbicides. The mean water concentrations (in ??g/L) of the pesticide residues in River Kuywa, which flows through the Nzoia Nucleus Estate sugarcane farms, ranged from 0.12 (lindane) to 1.36 (p,p??-DDT) for organochlorines and from 0.14 (atrazine) to 1.75 (diuron) for herbicides during the heavy rains period in August 2008 while the mean sediment concentrations (in ??g/g) ranged from 0.28 (lindane) to 1.87 (endrin) for organochlorines and 0.39 (hexazinone) to 4.61 (alachlor) for herbicides. The mean concentrations of residues in water during the light rain period in December 2008 ranged from 0.17 (p,p??-DDT) to 0.71 (aldrin) for organochlorines and 0.01 (atrazine) to 1.74 (alachlor) for herbicides while the sediment concentrations ranged from 0.38 (p,p??-DDT) to 1.145 (aldrin) for organochlorines and 0.74 (atrazine) to 1.98 (alachlor) for herbicides. Although DDT, aldrin, dieldrin, and endrin were not reported in the survey, their presence in the fallow experimental field plot soils and in River Kuywa water and sediment could indicate previous application, lack of recorded data or illegal usage since 1997 when they were banned. Notably, the concentrations of alachlor, diuron, cypermethrin, and hexazinone in the water column were substantial indicating their extensive usage and residual persistence in the sub-catchment, with subsequent wash-off and leaching into River Kuywa. The concentration levels of some of the individual pesticides exceeded the EU limit requirements for drinking water and indicated potential risk to humans and cattle if the water is used without treatment.