TRANSPORT OF SEDIMENT-BOUND ORGANOCHLORINE PESTICIDES TO THE SAN JOAQUIN RWER,CALIFORNIA1

ABSTRACT: Suspended sediment samples were collected in west-side tributaries and the main stem of the San Joaquin River, California, in June 1994 during the irrigation season and in January 1995 during a winter storm. These samples were analyzed for 15 organochiorine pesticides to determine their occurrence and their concentrations on suspended sediment and to compare transport during the irrigation season (April to September) to transport during winter storm runoff (October to March). Ten organochiorine pesticides were detected during the winter storm runoff; seven during the irrigation season. The most frequently detected organochlorine pesticides during both sampling periods were p,p'-DDE, p,p'-DDT, p,p'-DDD, dieldrin, toxaphene, and chiordane. Dissolved samples were analyzed for three organochiorine pesticides during the irrigation season and for 15 during the winter storm. Most calculated total concentrations of p,p-DDT, chlordane, dieldrin, and toxaphene exceeded chronic criteria for the protection of freshwater aquatic life. At eight sites in common between sampling periods, suspended sediment concentrations and streamfiow were greater during the winter storm runoff - median concentration of 3,590 mg/L versus 489 mg(L and median streamfiow of 162 ft³/s versus 11 ft³/s. Median concentrations of total DDT (sum of p,p'-DDD, p,p-DDE, and p,p'-DDT), chlordane, dieldrin, and toxaphene on suspended sediment were slightly greater during the irrigation season, but instantaneous loads of organochlorine pesticides at the time of sampling were substantially greater during the winter storm. Estimated loads for the entire irrigation season exceeded estimated loads for the January 1995 storm by about 2 to 4 times for suspended transport and about 3 to 11 times for total transport. However, because the mean annual winter runoff is about 2 to 4 times greater than the runoff during the January 1995 storm, mean winter transport may be similar to irrigation season transport. This conclusion is tentative primarily because of insufficient information on long-term seasonal variations in suspended sediment and organochlorine concentrations. Nevertheless, runoff from infrequent winter storms will continue to deliver a significant load of sediment-bound organochiorine pesticides to the San Joaquin River even if irrigation-induced sediment transport is reduced. As a result, concentrations of organochlorine pesticides in San Joaquin River biota will continue to be relatively high compared to other regions of the United States.     

Persistent organic pollutants in the environment: chlordane residues in compost

The half-lives of some persistent organic pollutants (POPs) in environmental compartments such as soil and air can be as long as decades. In spite of the hydrophobicity of many POPs, the literature contains reports of their uptake by, and translocation through, a variety of plants. Both these observations prompt the investigation of whether a vegetation-based environmental compartment such as compost contains significant residues of POPs. Previous reports imply that residues of technical chlordane will be found in compost. Due to its physicochemical properties, technical chlordane provides insights into the fate of POPs in the environment, which are not accessible through determinations of other pollutants in this group. Accordingly, we undertook the first comprehensive examination of technical chlordane residues in a variety of composts, specifically, 13 commercial and 39 municipal compost products, to both characterize and quantify the magnitude of this point source of contamination. Using chiral gas chromatography interfaced to ion trap mass spectrometry, the concentration and the compositional and enantiomeric profiles of chlordane components were determined. Of the 13 commercial products, 9 contained detectable chlordane concentrations, ranging from 4.7 to 292 microg/kg (dry wt.), while all 39 municipal products contained chlordane residues ranging from 13.9 to 415 microg/kg (dry wt.). The residue concentrations and profiles suggest possible feedstock sources for the chlordane in the finished compost product. The data also support the conclusion that some composts contribute to anthropogenic cycling of POPs through the biosphere.     

AN ORGANIZED SIGNAL IN SNOWMELT RUNOFF OVER THE WESTERN UNITED STATES1

ABSTRACT: Daily‐to‐weekly discharge during the snowmelt season is highly correlated among river basins in the upper elevations of the central and southern Sierra Nevada (Carson, Walker, Tuolumne, Merced, San Joaquin, Kings, and Kern Rivers). In many cases, the upper Sierra Nevada watershed operates in a single mode (with varying catchment amplitudes). In some years, with appropriate lags, this mode extends to distant mountains. A reason for this coherence is the broad scale nature of synoptic features in atmospheric circulation, which provide anomalous insolation and temperature forcing that span a large region, sometimes the entire western U.S. These correlations may fall off dramatically, however, in dry years when the snowpack is spatially patchy.     

Organochlorine residues in fish and water samples from lake victoria, Uganda

Nile tilapia and Nile perch samples from Lake Victoria were analyzed for lindane (gamma-1,2,3,4,5,6-hexachlorocyclohexane), aldrin (1,2,3,4,10,10-hexachloro-1,4,4a,5,8,8a-hexahydro-1,4:5,8-dimethanonaphthalene), alpha-endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3- benzo(e) dioxathiepin-3-oxide), dieldrin (1,2,3,4,10,10-hexachloro-6,7-epoxy-1,4,4a,5,6,7,8,8a-octahydro-1,4,5,8-dimethanonaphthalene), DDE (p,p'-1,1-dichloro-2,2-bis-(4-chlorophenyl)ethylene), and DDT (p,p'-1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane). No significant difference (alpha = 0.05) in the residue levels between fish types for lindane, alpha-endosulfan, p,p'-DDE, p,p'-DDT, and dieldrin was observed. The aldrin levels in Nile perch (Lates niloticus) were significantly higher than the levels in Nile tilapia (Oreochromis niloticus). No difference was observed in the distribution of residues in the different parts of Nile tilapia, although a difference for p,p'-DDE was observed in the Nile perch. No significant difference was observed in the average fat content of the tissue of Nile perch and Nile tilapia; however, the distribution of fat was significantly different in the different parts of the fish, with the abdominal portion having the highest amount of fat. There was no correlation observed in this study between fat content and organochlorine concentration. Lower p,p'-DDT residues levels compared with the p,p'-DDE levels observed in this study indicate that DDT is no longer in use. The levels of organochlorine pesticide residues found in fish samples in this study were below the FAO, U.S. FDA, Australian, and German extraneous residue limits and maximum residue limits. The concentration of organochlorine residues in surface water within the Napoleon Gulf of Lake Victoria was below detection limit (0.1 microg L(-1)).     

Spatial and temporal distribution of polychlorinated biphenyl (PCB) concentrations in soils of an industrialized city in Turkey

Surface soil (0-5 cm) samples from 43 sampling sites covering the entire urban territory of Bursa, an industrialized city in Turkey, were collected in each season and analyzed for 83 polychlorinated biphenyls (PCBs). The mean concentration of total PCBs (Σ83 PCBs) among all sites over the four seasons was 2121.51 pg/g dry weight (dw), with a range of 207.61-5461.95 pg/g dw. Total PCB concentrations in the soil samples collected near an industrial region were the highest in all seasons. In general, PCB patterns were dominated by low-chlorinated homologue groups (≤ 5 Cl groups at a 79% level). The predominant homologue group found in Bursa city soils was the penta-CBs (29.1%) followed by the tetra-CBs (25.5%) and tri-CBs (17.6%). A total of seven dioxin-like PCB congeners (CB-77, 81, 105, 114, 118, 123, and 126) were found in every sampling location and their mean total concentration for all locations and seasons was 259.27 pg/g dw, with a range of 7.02-1581.13 pg/g dw. A significant relationship (r = 0.77, p < 0.01) was found between the concentrations of dioxin-like PCBs and the seasonal average sum of PCB concentrations. A correlation between light congeners (相似文献   

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.     

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.     

VARIATIONS IN NORTHERN SIERRA NEVADA STREAMFLOW: IMPLICATIONS OF CLIMATE CHANGE1

ABSTRACT: Historical records of streamflow for an eastward- and a westward-draining stream in the northern Sierra Nevada have been analyzed for evidence of changes in runoff characteristics and patterns of variability. A trend of increasing and more variable winter streamflow began in the mid-1960s. Mean monthly streaniflow during December through March was substantially greater for water years 1965–1990 compared to water years 1939–1964. Increased winter and early-spring streamflow during the later period is attributed to small increases in temperature, which increase the rain-to-snow ratio at lower altitudes and cause the snowpack to melt earlier in the season at higher altitudes. The timing of snowmelt runoff on the western slope of the Sierra Nevada is more sensitive than it is on the eastern slope to changes in temperature, owing to predominantly lower altitudes on the west side. This difference in sensitivity suggests that basins on the east side of the Sierra Nevada have a more reliable water supply (as snow storage) than western-slope basins during warming trends.     

Population control of exotic rainbow trout in streams of a natural area park

Expansion of the distribution of exotic rainbow trout is thought to be a leading cause for the decline of native brook trout since the 1930s in Great Smoky Mountains National Park, USA. An experimental rehabilitation project was conducted from 1976 to 1981 using backpack electrofish shockers on four remnant brook trout populations sympatric with rainbow trout. The objectives were to evaluate the effectiveness of the technique to remove the exotic rainbow trout, to determine the population responses by native brook trout, and to evaluate the usefulness of the technique for trout management in the park.Rainbow trout populations were greatly reduced in density after up to six years of electrofishing, but were not eradicated. Rainbow trout recruitment, however, was essentially eliminated. Brook trout populations responded by increasing in density (including young-of-the-year), but rates of recovery differed among streams. The maximum observed densities ir each stream occurred at the end of the project.The findings suggest that electrofishing had a major negative impact on the exotic species, which was followed by positive responses from the native species in the second and third order study streams. The technique would probably be less effective in larger (fourth-order) park streams, but as an eradication tool the technique may have its highest potential in small first order streams. Nonetheless, the technique appears useful for population control without causing undue impacts on native aquatic species, although it is labor intensive, and capture efficiency is greatly influenced by fish size and stream morphology. To completely remove the exotic fish from selected streams, different technologies will have to be explored and developed.     

Characterization of the pesticide chlordane in estuarine river sediments

Sediments are increasingly recognized as both carrier and potential source of contaminants in aquatic environments. This study investigated the characteristics and spatial distribution of total chlordane and its three most abundant compounds, including alpha-chlordane, gamma-chlordane, and trans-nonachlor, in sediments from the Cedar and Ortega rivers, Florida, USA, using geographic information system (GIS)-based kriging analyses and field measurements. Kriging analysis showed that two areas, one from the Cedar River area and the other from the northern end of the Ortega River area, were contaminated. The maximum concentrations of total chlordane, gamma-chlordane, alpha-chlordane, and trans-nonachlor in the sediments were, respectively, 101.8, 20.1, 26.3, and 19.2 microg/kg. A plot of total organic carbon (TOC)-normalized chlordane concentrations showed that effects of grain size on sediment chlordane contamination were negligible. A principal axis analysis further revealed that a linear correlation existed between alpha-chlordane and total chlordane as well as between gamma-chlordane and total chlordane, whereas no correlation existed between trans-nonachlor and total chlordane. Comparison of total chlordane concentration with Florida Sediment Assessment Guidelines showed that the Cedar River and the northern end of the Ortega River had total chlordane concentrations above the probable effect level (4.79 microg/kg), which could pose a potential risk to aquatic life.     

THE POTENTIAL FOR INCREASING STREAMFLOW FROM SIERRA NEVADA WATERSHEDS1

The Sierra Nevada produces over 50 percent of California's water. Improvement of water yields from the Sierra Nevada through watershed management has long been suggested as a means of augmenting the state's water supply. Vegetation and snowpack management can increase runoff from small watersheds by reducing losses due to evapotranspiration, snow interception by canopy, and snow evaporation. Small clearcuts or group selection cuts creating openings less than half a hectare, with the narrow dimension from south to north, appear to be ideal for both increasing and delaying water delivery in the red fir-lodgepole pine and mixed-conifer types of the Sierra west slope. Such openings can have up to 40 percent more snow-water equivalent than does uncut forest. However, the water yield increase drops to 1/2-2 percent of current yield for an entire management unit, due to the small number of openings that can be cut at one time, physical and management constraints, and multiple use/sustained yield guidelines. As a rough forecast, water production from National Forest land in the Sierra Nevada can probably be increased by about 1 percent (0.6 cm) under intensive forest watershed management. Given the state of reservoir storage and water use in California, delaying streamflow is perhaps the greatest contribution watershed management can make to meeting future water demands.     

DEVELOPMENT OF WATERSIIED MODELS FOR TWO SIERRA NEVADA BASINS USING A GEOGRAPHIC INFORMATION SYSTEM1

ABSTRACT: Techniques were developed using vector and raster data in a geographic information system (GIS) to define the spatial variability of watershed characteristics in the north-central Sierra Nevada of California and Nevada and to assist in computing model input parameters. The U.S. Geological Survey's Precipitation-Runoff Modeling System, a physically based, distributed-parameter watershed model, simulates runoff for a basin by partitioning a watershed into areas that each have a homogeneous hydrologic response to precipitation or snowmelt. These land units, known as hydrologic-response units (HRU's), are characterized according to physical properties, such as altitude, slope, aspect, land cover, soils, and geology, and climate patterns. Digital data were used to develop a GIS data base and HRIJ classification for the American River and Carson River basins. The following criteria are used in delineating HRU's: (1) Data layers are hydrologically significant and have a resolution appropriate to the watershed's natural spatial variability, (2) the technique for delineating HRU's accommodates different classification criteria and is reproducible, and (3) HRU's are not limited by hydrographic-subbasin boundaries. HRU's so defined are spatially noncontiguous. The result is an objective, efficient methodology for characterizing a watershed and for delineating HRU's. Also, digital data can be analyzed and transformed to assist in defining parameters and in calibrating the model.     

云南虹鳟鱼的产业化发展前景

分析了国内外虹鳟鱼的发展状况，以及云南虹鳟鱼的产业化前景，提出了相应的发展对策。     

ASSESSING FLUSHING-FLOW REQUIREMENTS FOR BROWN TROUT SPAWNING GRAVELS IN STEEP STREAMS1

Flushing flows are re1eses from dams designed to remove fine sediment from downstream spawning habitat. We evaluated flushing flows on reaches proposed for hydroelectric diversions on seven streams in the eastern Sierra Nevada, California, with wild populations of brown trout (Salmo trutta). The stream reaches are steep (average map slopes range from 7 to 17 percent), are dominated by boulder cascades, and afford few opportunities for gravel deposition. Methods for estimating flushing flows from flow records, developed from studies in other localities, produced widely differing results when applied to the study streams, probably reflecting differences in the hydrologic and geomorphic characteristics of the streams on which the methods were developed. Tracer gravel experiments demonstrated that all sampled gravels were washed out by the flows of 1986, a wet year. Size analyses of gravel samples and hydraulic data from field surveys were used in tractive-force calculations in an attempt to specify the flow required to flush the gravels. However, these calculations produced some unrealistic results because the flows were nonuniform in the study reaches. This suggests that the tractive-force approach may not be generally applicable to small, steep streams where nonuniform flow conditions prevail.     

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.     

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.     

Contaminants evaluation of Marais des Cygnes National Wildlife Refuge in Kansas and Missouri,USA

At the new Marais des Cygnes National Wildlife Refuge in Linn County, Kansas, and Bates County, Missouri, USA, we evaluated long-lived contaminants before acquisition of the land for the refuge. We sampled sediments at 16 locations and fish at seven locations. The samples were analyzed for metals and for chlorinated hydrocarbon compounds. Selected sediment samples also were analyzed for aliphatic hydrocarbons. Arsenic concentrations in sediment samples from six locations were elevated compared to US norms, but arsenic was not detected in any fish composite. Mercury concentrations in largemouth bass from two locations were comparable to the 85th percentile concentrations in nationwide fish collections. Most sediment concentrations of other metals were unlikely to have detrimental effects on biota. No chlorinated hydrocarbons were detected in any sediment sample. Chlordane compound concentrations in fish composites from two sites at the eastern end of the sampling area were 0.127 and 0.228 μg/g wet weight, respectively, which are high enough to cause concern. Most aliphatic hydrocarbons detected were found at low concentrations and probably were natural in origin. We concluded that there are no serious contaminants concerns within the project area, but past use of arsenical pesticides may mean a legacy of elevated soil arsenic levels in parts of the area and some use of banned pesticides such as chlordane and DDT likely is still occurring near the refuge.     

FACTORS INFLUENCING ACUTE TOXICfrY OF COAL ASH TO RAINBOW TROUT (SALMO GAIRDNERI) AND BLUEGILL SUNFISH (LEPOMIS MACROCHIRUS)1

ABSTRACT: The potentially toxic components in coal ash (ash particles, heavy metals) were evaluated in laboratory static, acute (96 hr) bioassays, both separately and in various combinations with extreme pH (5.0 and 8.5), using rainbow trout (Salmo gairdneri) and bluegifi sunfish (Lepomis macrochirus). Ash particle morphology and metal distribution anlaysis, using electron microscopy and surface-subsurface analysis by ion microscopy, showed that metals could be either clumped or evenly distributed on the surface of fly ash. Surface enrichment on fly ash particles from electrostatic precipitators, as measured by ion microscopy, was found for cadmium, copper, chromium, nickel, lead, mercury, titanium, arsenic, and selenium. Bottom (heavy) ash was not acutely toxic to either fish species at concentrations of up to 1500 mg/l total suspended solids (TSS) at pH 5.0, 7.5, or 8.5. Fly ash particles were not acutely toxic to blue-gill at levels up to 1360 mg/l TSS. Rainbow trout were highly sensitive to fly ash (25 to 60 percent mortality) at concentrations of 4.3 to 20.5 mg/I TSS when dissolved metal availability was high but were not sensitive at higher particulate concentrations (58 to 638 mg/I TSS) when dissolved metals were low. When metals were acid-leached from fly ash prior to testing, no rainbow trout mortality occurred at TSS concentrations of up to 2,350 mg/l TSS. When the percent of dissolved metal was high (e.g., 50–90 percent of the total), fish mortality was increased. Rainbow trout were nearly two orders of magnitude more sensitive than bluegill when subjected to a blend of cadmium, chromium, copper, nickel, lead, and zinc. The two species were similar in their acute sensitivity to acidic pH at levels at or below 4.0 and alkaline pH of 9.1. If the pH of coal ash effluent is contained within the range 6.0 to 9.0, acute toxicity to fish can be attributed to trace element availability from fly ash but not heavy ash. Control of holding pond and effluent pH and maximizing pond residence time are important strategies for minimizing effects of ash pond discharges on fish.     

EFFECTS OF INSECTICIDE USE IN A PINE SEED ORCHARD ON PESTICIDE LEVELS IN FISH1

ABSTRACT: A hydroelectric lake on the Oconee River in central Georgia was sampled on a quarterly basis for four years to determine the impact of three insecticides on the pesticide loading of fish. The insecticides carbofuran (2,3,-dihydro-2,2-dimethyl-7-benzofuranyl methyl-carbamate), fenvalerate [cyano(3-phenoxyphenyl)methyl 4-chloro alpha (1-methylethyl)benzeneacetate], and azinphosmethyl [0,0-Dimethyl S-(4-oxo-1,2,3-benzotriazin-3-(4H)-ylmethyl phosphorodithioate] were used to control cone and seed insects on a pine seed orchard that is adjacent to Lake Oconee. Fish populations in areas of the lake that receive runoff from treated and untreated portions of the seed orchard were sampled using gill nets. Water and fish samples were collected monthly in 1981–1983 and quarterly in 1984. Species collected included carp (Cyprinus carpio), sucker (Catostomus spp., Erimyzon spp., Moxostoma spp., Minytrema spp.), bass (Micropterus spp.), channel catfish (Ictalurus punctatus), spotted gar (Lepisosteus spp.), and bluegill sunfish (Lepomis macrochirus). Few carbofuran residues (< 7 percent of fish samples contained detectable residues) and no azinphosmethyl or fenvalerate residues were detected despite measured inputs into the lake after insecticide application. Persistent agricultural insecticides including dieldrin, lindane, DDT, and toxaphene were detected in 32, 36, 58, and 83 percent of sampled fish, respectively. Screening for 20 other insecticides resulted in no detection of residues at a detection limit of 30–100 μg kg^-1.