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USGS2002

Comparison of automated segmented-flow and discrete analyzers for the determination of nutrients in water

Water samples with specific conductances ranging from 66 to 6950 ??mho/cm at 25 ??C were analyzed for ammonia-N (NH3-N), nitrate plus nitrite-N (NO3 + NO2-N), nitrite-N (NO2-N), and phosphate-P (PO4-P) by using both a "segmented-flow" analyzer and a "discrete" analyzer. Plots of the discrete vs. the segmented-flow results showed linear correlation coefficients of 0.9980 for NH3-N, 0.9997 for NO3 + NO2-N, 0.9998 for NO2-N, and 0.9950 for PO4-P. The significances of the slope and the y intercept of each plot are discussed in terms of possible biases which may exist between the two systems. Data concerning precision and accuracy for both analyzers are presented. For the four analytes, the rate of sample analysis was 60 samples per hour on the discrete analyzer and 40 samples per hour on the segmented-flow analyzer. ?? 1981 American Chemical Society.

Environmental Science & Technology↗
USGS2002

Migration through soil of organic solutes in an oil-shale process water

The migration through soil of organic solutes in an oil-shale process water (retort water) was studied by using soil columns and analyzing leachates for various organic constituents. Retort water extracted significant quantities of organic anions leached from ammonium-saturated-soil organic matter, and a distilled-water rinse, which followed retort-water leaching, released additional organic acids from the soil. After being corrected for organic constitutents extracted from soil by retort water, dissolved-organic-carbon fractionation analyses of effluent fractions showed that the order of increasing affinity of six organic compound classes for the soil was as follows: hydrophilic neutrals nearly equal to hydrophilic acids, followed by the sequence of hydrophobic acids, hydrophilic bases, hydrophobic bases, and hydrophobic neutrals. Liquid-chromatographic analysis of the aromatic amines in the hydrophobic- and hydrophilic-base fractions showed that the relative order of the rates of migration through the soil column was the same as the order of migration on a reversed-phase, octadecylsilica liquid-chromatographic column.

Environmental Science & Technology↗
USGS2000

Beryllium-7 as a tracer of short-term sediment deposition and resuspension in the Fox River Wisconsin

Short-term (∼monthly) sediment deposition and resuspension rates of surficial bed sediments in two PCB-laden impoundments on the Fox River, WI, were determined in the summer and fall of 1998 using 7 Be, a naturally occurring radioisotope produced in the atmosphere. Decay-corrected activities and inventories of 7 Be were measured in bed sediment and in suspended particles. Beryllium-7 activities generally decreased with depth in the top 5−10 cm of sediments and ranged from undetectable to ∼0.9 pCi cm - 3 . Inventories of 7 Be, calculated from the sum of activities from all depths, ranged from 0.87 to 3.74 pCi cm - 2 , and the values covaried between sites likely reflecting a common atmospheric input signal. Activities of 7 Be did not correlate directly with rainfall. Partitioning the 7 Be flux into “new” and “residual” components indicated that net deposition was occurring most of the time during the summer. Net erosion, however, was observed at the upstream site from the final collection in the fall. This erosion event was estimated to have removed 0.10 g (cm of sediment) - 2 , corresponding to ∼0.5 cm of sediment depth, and ∼6−10 kg of polychlorinated biphenyls (PCBs) over the whole deposit. Short-term accumulation rates were up to ∼130 times higher than the long-term rates calculated from 137 Cs profiles, suggesting an extremely dynamic sediment transport environment, even within an impounded river system.

Environmental Science & Technology↗
USGS2000

Atmospheric transport, deposition, and fate of triazine herbicides and their metabolites in pristine areas at Isle Royale National Park

Trace concentrations of triazine herbicides, used in the Midwestern United States, are being transported atmospherically hundreds of kilometers and deposited by precipitation onto pristine areas, such as Isle Royale National Park (Lake Superior). Atrazine, deethylatrazine, deisopropylatrazine, and cyanazine were detected in Isle Royale rainfall from mid-May to early July (1992−1994) at concentrations of less than 0.005 to 1.8 μg/L. Analysis of predominant wind direction indicated that the herbicides originated from the upper Midwestern United States. The annual mass of herbicides deposited by rainfall varied between years, from 13.4 μg/m 2 /yr for 1992, 3.7 μg/m 2 /yr for 1993, and 54 μg/m 2 /yr for 1994. Atrazine and deethylatrazine were found also in concentrations of less than 5−22 ng/L in lakes across Isle Royale. Concentrations of atrazine in the surface layer of the lakes increased during deposition periods and decreased later in the year. The fate of triazines in shallow lakes suggests faster degradation and shorter half-lives, while deeper lakes have residence times for atrazine that may exceed 10 years.

Environmental Science & Technology↗
USGS2000

Bioavailability of particle-associated Se to the bivalve Potamocorbula amurensis

Elemental selenium, Se(0), is a prevalent chemical form in sediments, but little is known about its bioavailability. We evaluated the bioavailability of two forms of Se(0) by generating radioisotopic 75 Se(0) through bacterial dissimilatory reduction of 75 SeO 3 2 - by pure bacterial cultures (SES) and by an anaerobic sediment microbial consortium (SED). A third form was generated by reducing 75 SeO 3 2 - with ascorbic acid (AA). Speciation determinations showed that AA and SES were >90% Se(0), but SED showed a mixture of Se(0), selenoanions, and a residual fraction. Pulse-chase techniques were used to measure assimilation efficiencies (AE) of these particulate Se forms by the bivalve Potamocorbula amurensis . Mean AE values were 3 ± 2% for AA, 7 ± 1% for SES, and 28 ± 15% for SED, showing that the bioavailability of reduced, particle-associated Se is dependent upon its origin. To determine if oxidative microbial processes increased Se transfer, SES 75 Se(0) was incubated with an aerobic sediment microbial consortium. After 113 d of incubation, 36% of SES Se(0) was oxidized to SeO 3 2 - . Assimilation of total particulate Se was unaffected however (mean AE = 5.5%). The mean AE from the diatom Phaeodactylum tricornutum was 58 ± 8%, verifying the importance of Se associated with biogenic particles. Speciation and AE results from SED suggest that selenoanion reduction in wetlands and estuaries produces biologically available reduced selenium.

Environmental Science & Technology↗
USGS2002

Accumulation by fish of contaminants released from dredged sediments

Inasmuch as the process of dredging and disposing of dredged materials causes a resuspension of these materials and an increase in bioavailability of associated contaminants, we conducted a series of experiments to examine the potential accumulation by fish of contaminants from suspended sediments. In the first experiment we compared accumulation of contaminants by yellow perch of hatchery and lake origin and found that after 10 days of exposure to nonaerated sediments, fish of hatchery origin accumulated PCBs and Fe, while fish of lake origin accumulated As, Cr, Fe, and Na. Two additional exposures were conducted to evaluate the effects of aerating the sediments prior to measuring bioavailability of associated contaminants. Fish of hatchery origin exposed to nonaerated sediments for 10 days accumulated PCBs and Hg, while fish of hatchery origin exposed to aerated sediments for 10 days accumulated PCBs, DDE, Zn, Fe, Cs, and Se. These results demonstrated not only the potential for uptake of contaminants by fish as a result of dredging but also the potential utility of fish bioassays in evaluating proposed dredging operations.

Environmental Science & Technology↗
USGS2000

Influence of acid volatile sulfide and metal concentrations on metal bioavailability to marine invertebrates in contaminated sediments

An 18-day microcosm study was conducted to evaluate the influence of acid volatile sulfides (AVS) and metal additions on bioaccumulation from sediments of Cd, Ni, and Zn in two clams ( Macoma balthica and Potamocorbula amurensis ) and three marine polychaetes ( Neanthes arenaceodentata, Heteromastus filiformis, and Spiophanes missionensis ). Manipulation of AVS by oxidation of naturally anoxic sediments allowed use of metal concentrations typical of nature and evaluation of processes important to chronic metal exposure. A vertical sediment column similar to that often found in nature was used to facilitate realistic biological behavior. Results showed that AVS or porewater (PW) metals controlled bioaccumulation in only 2 of 15 metal-animal combinations. Bioaccumulation of all three metals by the bivalves was related significantly to metal concentrations extracted from sediments (SEM) but not to [SEM − AVS] or PW metals. SEM predominantly influenced bioaccumulation of Ni and Zn in N. arenaceodentata , but Cd bioaccumulation followed PW Cd concentrations. SEM controlled tissue concentrations of all three metals in H. filiformis and S. missionensis , with minor influences from metal-sulfide chemistry. Significant bioaccumulation occurred when SEM was only a small fraction of AVS in several treatments. Three factors appeared to contribute to the differences between these bioaccumulation results and the results from toxicity tests reported previously: differences in experimental design, dietary uptake, and biological attributes of the species, including mode and depth of feeding.

Environmental Science & Technology↗
USGS2000

Influence of acid volatile sulfides and metal concentrations on metal partitioning in contaminated sediments

The influence of acid volatile sulfide (AVS) on the partitioning of Cd, Ni, and Zn in porewater (PW) and sediment as reactive metals (SEM, simultaneously extracted metals) was investigated in laboratory microcosms. Two spiking procedures were compared, and the effects of vertical geochemical gradients and infaunal activity were evaluated. Sediments were spiked with a Cd−Ni−Zn mixture (0.06, 3, 7.5 μmol/g, respectively) containing four levels of AVS (0.5, 7.5, 15, 35 μmol/g). The results were compared to sediments spiked with four levels of Cd−Ni−Zn mixtures at one AVS concentration (7.5 μmol/g). A vertical redox gradient was generated in each treatment by an 18-d incubation with an oxidized water column. [AVS] in the surface sediments decreased by 65−95% due to oxidation during incubation; initial [AVS] was maintained at 0.5−7.5 cm depth. PW metal concentrations were correlated with [SEM − AVS] among all data. But PW metal concentrations were variable, causing the distribution coefficient, Kd pw (the ratio of [SEM] to PW metal concentrations) to vary by 2−3 orders of magnitude at a given [SEM − AVS]. One reason for the variability was that vertical profiles in PW metal concentrations appeared to be influenced by diffusion as well as [SEM − AVS]. The presence of animals appeared to enhance the diffusion of at least Zn. The generalization that PW metal concentrations are controlled by [SEM − AVS] is subject to some important qualifications if vertical gradients are complicated, metal concentrations vary, or equilibration times differ.

Environmental Science & Technology↗
USGS2000

Comparing polychlorinated biphenyl concentrations and patterns in the Saginaw River using sediment, caged fish, and semipermeable membrane devices

Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, MI, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in caged fish, and 77 to 790 ng/g in SPMDs. Previously reported rates of PCB accumulation by SPMDs were used to estimate aqueous concentrations from the PCB concentrations detected in the SPMDs. Sediment-water partition coefficients were used to estimate aqueous PCB concentrations from sediment. Steady-state bioconcentration factors and depuration rate constants were used to estimate dissolved PCB concentrations from caged channel catfish. Relative PCB patterns from the SPMDs, caged fish, and sediment were compared using principal components analysis. SPMD and sediment samples provide complementary information. Sediments reflect long-term accumulation and weathering, while SPMDs integrate water concentrations only during the sampling period. Because of higher water solubilities of lower-chlorinated PCBs these predominate in the SPMDs as compared to in the fish and sediments. Contaminant profile differences between caged fish and SPMDs are likely due to metabolism and depuration of certain PCB congeners by fish.Three techniques of assessing bioavailable polychlorinated biphenyls (PCBs) in the Saginaw River, Ml, were compared: sediments, caged fish, and semipermeable membrane devices (SPMDs). SPMDs and caged fish were placed in the river for 28 days at five sites where sediments were also sampled. The samples were analyzed for PCB congeners to determine concentrations and patterns. Total PCB concentrations ranged from 33 to 280 ng/g (dry weight) in sediments, 46 to 290 ng/g (wet weight) in caged fish, and 77 to 790 ng/g in SPMDs. Previously reported rates of PCB accumulation by SPMDs were used to estimate aqueous concentrations from the PCB concentrations detected in the SPMDs. Sediment-water partition coefficients were used to estimate aqueous PCB concentrations from sediment. Steady-state bioconcentration factors and depuration rate constants were used to estimate dissolved PCB concentrations from caged channel catfish. Relative PCB patterns from the SPMDs, caged fish, and sediment were compared using principal components analysis. SPMD and sediment samples provide complementary information. Sediments reflect long-term accumulation and weathering, while SPMDs integrate water concentrations only during the sampling period. Because of higher water solubilities of lower-chlorinated PCBs these predominate in the SPMDs as compared to in the fish and sediments. Contaminant profile differences between caged fish and SPMDs are likely due to metabolism and depuration of certain PCB congeners by fish.At five sites in the Saginaw River, MI, PCB concentrations were determined in the summer of 1993 using three methods: sediment analysis, concentrations in caged fish, and concentrations in semipermeable membrane devices (SPMDs). On average, total PCB concentrations in the SPMDs were twice those found in caged fish, and the SPMD-to-fish concentration ratios of di-, tri-, tetra-, and pentaCB homologues were 10.0, 3.0, 2.5, and 1.4, respectively. Average concentrations in the sediments were approximately half those in the SPMDs, and the caged fish showed a greater preponderance of higher log octanol-water partition coefficient PCBs similar to the sediment pattern. On average, the water PCB concentrations estimated from sediment concentrations were five times higher than those calculated from SPMDs and three times higher than those estimated from caged fish. The total PCB concentrations in sediment, caged fish, and SPMDs ranged 33-280, 46-290, and 77-790 ng/g, respectiv

Environmental Science & Technology↗
USGS2001

Effect of scale on the behavior of atrazine in surface waters

Field runoff is an important transport mechanism by which agricultural pesticides, including atrazine, move into the hydrologic environment. Atrazine is chosen because it is widely used, is transported in runoff relatively easily, is widely observed in surface waters, and has relatively little loss in the stream network. Data on runoff of atrazine from experimental plot and field studies is combined with annual estimates of load in numerous streams and rivers, resulting in a data set with 408 observations that span 14 orders of magnitude in area. The load as a percent of use (LAPU) on an annual basis is the parameter that is compared among the studies. There is no difference in the mean or range of LAPU values for areas from the size of experimental field plots (???0.000023 ha) and small watersheds (<100 000 ha). The relatively invariant LAPU value observed across a large range of watershed areas implies that the characteristics of atrazine itself (application method and chemical properties) are important in determining the extent of runoff. The variable influences on the extent of runoff from individual watershed characteristics and weather events are superimposed on the relatively invariant LAPU value observed across the range of watershed areas. The results from this study establish the direct relevance for agricultural field plot studies to watershed studies across the full range of scale.

Environmental Science & Technology↗
USGS2000

Cytochrome P450 1A expression in midwater fishes: Potential effects of chemical contaminants in remote oceanic zones

Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are aryl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A activity, was detected in liver from all species in 1977/78. In some, including Gonostoma elongatum, AHH was inhibited by the CYP1A inhibitor ??-naphthoflavone. CYP1A-dependent ethoxyresorufin O-deethylase (EROD) was detected in liver microsomes of all species in 1993; rates were highest in G. elongatum and Argyropelecus aculeatus. Immunoblot analysis with the CYP1A-specific monoclonal antibody 1-12-3 detected a single microsomal protein band in most 1993 samples; the highest content was in G. elongatum. Immunohistochemical analysis showed CYP1A staining in gill, heart, kidney, and/or liver of several species. Extracts of the 1993 G. elongatum and A. aculeatus, when applied to fish hepatoma cells (PLHC-1) in culture, elicited a significant induction of EROD in those cells. The capacity of the extracts to induce CYP1A correlated with the content of PCBs measured in the same fish (2-4.6 ng/g total body weight). Mesopelagic fish in the western North Atlantic, which experience no direct exposure to surface waters or sediments, are exposed chronically to inducers of CYP1A at levels that appear to be biochemically active in those fish.Cytochrome P450 1A (CYP1A) induction is a robust marker for exposure to polynuclear aromatic hydrocarbons and planar halogenated aromatic hydrocarbons that are awl hydrocarbon receptor agonists. We examined CYP1A expression in mesopelagic fishes from the western North Atlantic. Individuals in 22 species were obtained from slope water and the Sargasso Sea in 1977, 1978, and 1993. Aryl hydrocarbon hydroxylase (AHH), a CYP1A activity, was detected in liver from all species in 1977/78. In some, including Gonostoma elongatum, AHH was inhibited by the CYP1A inhibitor ??-naphthoflavone. CYP1A-dependent ethoxyresorufin O-deethylase (EROD) was detected in liver microsomes of all species in 1993; rates were highest in G. elongatum and Argyropelecus aculeatus. Immunoblot analysis with the CYP1A-specific monoclonal antibody 1-12-3 detected a single microsomal protein band in most 1993 samples; the highest content was in G. elongatum. Immunohistochemical analysis showed CYP1A staining in gill, heart, kidney, and/or liver of several species. Extracts of the 1993 G. elongatum and A. aculeatus, when applied to fish hepatoma cells (PLHC-1) in culture, elicited a significant induction of EROD in those cells. The capacity of the extracts to induce CYP1A correlated with the content of PCBs measured in the same fish (2-4.6 ng/g total body weight). Mesopelagic fish in the western North Atlantic, which experience no direct exposure to surface waters or sediments, are exposed chronically to inducers of CYP1A at levels that appear to be biochemically active in those fish.

Environmental Science & Technology↗