University of Vermont

Vermont Water Resources & Lake Studies Center

VT Water Center publications

Project Publications


Young, E.O., D.S. Ross, B.J. Cade-Menun, and C.W. Liu. 2013. Phosphorus Speciation in Riparian Soils: A Phosphorus-31 Nuclear Magnetic Resonance Spectroscopy and Enzyme Hydrolysis Study. Soil Science Society of American Journal doi:10.2136/sssaj2012.0313

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In the Lake Champlain Basin, phosphorus (P) loading from streambank erosion and cropland are both important P sources, and a better understanding of the factors affecting riparian P loss is needed to help prioritize riparian restoration efforts. We utilized solution phosphorus-31 nuclear magnetic resonance (NMR) spectroscopy and an enzyme hydrolysis method to characterize P and assess bioavailability in 14 commonly mapped riparian soils from northwestern Vermont. Surface horizons were sampled from distinct series at two riparian restoration sites to capture a range of soil properties. Samples were extracted with sodium hydroxide–ethylenediaminetetra-acetic acid (NaOH-EDTA) and analyzed by solution 31P NMR to speciate and quantify P compounds, and commercially available phosphatase enzymes were used to fractionate water-extractable molybdate unreactive P (MUP) into labile orthophosphate monoesters and orthophosphate diesters. Phosphorus extracted by NaOH-EDTA ranged from 74 to 510 mg P kg-1 (representing 14.2 to 31.9% of total soil P), of which 58 ± 13% was identified as organic P. Phosphorus compounds identified in all samples included myo-inositol hexakisphosphate (myo-IHP), scyllo-IHP, neo-IHP, chir-IHP, glycerophosphate, glucose 6-phosphate, mononucleotides, choline phosphate, glucose 1-phosphate, DNA, pyrophosphate, and orthophosphate. Orthophosphate monoesters accounted for 53.7 ± 12.3% of total NaOH-EDTA extractable P and 93 ± 3% of the NaOH-EDTA organic P, indicating the importance of organic P in these soils. Stereoisomers of IHP accounted for 29 ± 7% of NaOH-EDTA extractable Po. For the water extractions, 78 ± 13% of total P was MUP, of which 18 ± 6% was labile orthophosphate monoesters and 31 ± 15% was orthophosphate diesters. Results suggest that analytical
indices of riparian P loss potential should consider both organic and inorganic P.

Young, E.O., D.S. Ross, C. Alves, and T. Villars. 2012. Influence of soil series on phosphorus forms and availability at two riparian sites in the Lake Champlain Basin (Vermont). J. Soil Water Conserv.

Ishee, E.I. 2011. Characterizing phosphorus in eroding streambank soils in Chittenden County, Vermont. M.S. Thesis, Dept. Plant & Soil Science, Univ. Vermont, 90 pp.

Besaw, LE., D.M. Rizzo, P.R. Bierman, and W. Hackett. In Revision, 2009. Advances in ungauged streamflow prediction using neural networks. Journal of Hydrology. doi:10.1016/j.jhydrol.2010.02.037.2010.

Johnson, N.R. and Hill, J.E. 2010 (accepted). Phosphorus composition of a poultry manure-amended soil via enzymatic hydrolysis: demonstration of a high-throughput method and hints on enzyme-labile P. Soil Science Society of America Journal.

Besaw, LE., D.M. Rizzo, M. Kline, K.L. Underwood, J.J. Doris, L.A. Morrissey and K. Besaw, LE., D.M. Rizzo, M. Kline, K.L. Underwood, J.J. Doris, L.A. Morrissey and K. Pelletier. 2009. Stream classification using hierarchical artificial neural networks: A fluvial hazard management tool. Journal of Hydrology, Accepted April 6, 2009, DOI: 10.1016/j.jhydrol.2009.04.007, 2009.

Kominami, H. 2009. Synthesizing Summer Water Quality Monitoring Data from Shelburne Farms (2004-2008). Shelburne Farm Technical Report. University of Vermont Plant and Soil Science Department, 35pp. (PDF)

Shanley, J. B. and B. Wemple. 2009. Water Quality and Quantity in the Mountain Environment, in J. E. Milne, J. LeMense, and R. A. Virginia (eds.), Mountain Resorts: Ecology and the Law, Surrey, U.K., Ashgate Publishing Ltd.

Ambers, R. K. R., and B. C. Wemple. 2008. Reservoir sedimentation dynamics: Interplay and implications of human and geologic processes. Northeastern Geology and Environmental Science 30(1):49-60.

Burgess, Heather D. 2007. Geochemical Indicators of Productivity Change in Lake Champlain, USA-Canada. MS Thesis, The University of Vermont, Burlington, VT. 191 pages.

Wemple, B. C., J. Shanley, J. Denner, D. Ross, and K. Mills. 2007. Hydrology and water quality in two mountain basins of the northeastern US: assessing baseline conditions and quality in two mountain basins of the northeastern US: assessing baseline conditions and effects of ski area development. Hydrological Processes, DOI: 10.1002/hyp.6700.

O'Neil-Dunne, JPM and LA Morrissey. 2006. A GIS-Based Method for the Identification of Candidate Riparian Buffer Zones. American Water Resources Association 2006 Spring Specialty Conference, GIS and Water Resources IV, May 8-10, 2006, Houston, TX.

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Best management practices such as riparian buffers, can significantly reduce the amount of agricultural nonpoint source (NPS) pollution. In an effort to reduce NPS pollution in Vermont, the Natural Resource Conservation Service (NRCS) established a program to provide financial incentives to farmers to develop riparian buffers adjacent to their agricultural fields. The NRCS approach involved identifying candidate agricultural fields by manually interpreting hardcopy aerial photographs. This approach, however, does not account for geophysical factors such as soil type, slope, land cover, and hydrology that also significantly and directly influence agricultural runoff. A method based on the Revised Universal Soil Loss Equation (RUSLE) that incorporates hydrologic flow modeling to identify and prioritize candidate agricultural fields for riparian buffer development has been developed and is presented here. Implementation of the RUSLE model within a GIS framework also provides a methodology that can be readily extrapolated to surrounding regions in a cost effective manner. The model proved to be effective in providing a rapid assessment of fields most likely to contribute NPS pollution to nearby aquatic ecosystems, but was limited in its ability to accurately model hydrologic flow patterns due to the coarse resolution of elevation data and over-simplification of the flow patterns by the flow modeling algorithm.

Wheeler, S. M. 2006. An evaluation of the utility of remote sensing for monitoring cyanobacteria in Lake Champlain, thesis completed in fulfillment of Master of Science degree, University of Vermont, October 2006, 89 pages.

Ferber, L.R., S.N. Levine, A. Lini and G.P. Livingston. 2004. Do cyanobacteria dominate in eutrophic lakes because they fix atmospheric nitrogen? Freshwater Biology 49: 690-708.

Dybas, C. 2003. Harmful algal blooms: Biosensors provide new ways of detecting and monitoring Growing threat in coastal waters. BioScience 53(10): 918-923. 2003.

Sargent, Deborah H. 2001, Spatial and Temporal Distribution of Escherichia coli in the Mad River Watershed, Vermont, M.S. Thesis, School of Natural Resources, University of Vermont, 68 pp. Advisor: Morrissey.

Papadopoulou MP, GF Pinder and GP Karatzas. 2000. Optimal Management of a Coastal Aquifer Using Least-Cost Technology, Proceedings of the XIII International Conference on Computational Methods in Water Resources, Vol. I, pp. 561-566, Calgary Alberta, Canada.

Abbott, MD and Stanley, RS. 1999. Modeling groundwater recharge and flow in an upland fractured bedrock aquifer. System Dynamics Review 15(2): 163-184.

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This article describes a system dynamics model to simulate recharge and flow mechanisms in a fractured bedrock aquifer in northwestern Vermont. The model was constructed to aid in the interpretation of data collected as part of a stable and radiogenic isotope study of groundwater. Use of the model guided data collection and analysis throughout the course of the study, leading to the derivation of equations describing temporal and spatial changes in recharge and flow mechanisms in the study area.

Borchardt, MA. 1994. Effects of flowing water on nitrogen- and phosphorus-limited photosynthesis and optimum N:P rations by Spirogyra fluviatilis (charophyceae). Journal of Phycology 30(30):418-430.

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The effects of flowing water on net photosynthesis, dark respiration, specific growth rate, and optimum N:P ratios by Spirogyra fluviatilis Hilse were assessed. The alga was cultivated under nitrogen or phosphorus limitation in laboratory streams at three flow velocities: 3, 12, and 30 cm·s-1. The Droop equation adequately described respiration and photosynthesis (PSnet) as a function of N or P cell quota (QN or Qp). The data show that for N- or P-limited Spirogyra fluviatilis, flowing water is physiologically costly. Generally, flowing water had little effect on respiration rates; however, the proportion of gross photosynthesis devoted to dark respiration did increase with flow velocity. For photosynthesis, the minimum N and P cell quotas increased with velocity, and the theoretical PSnet maxima for N and P both appeared greatest at 12 cm·s-1. The Droop models showed that for any given QN or Qp, PSnet, was reduced by the 30-cm·s-1 treatment. Consistent with this finding, independent estimates of specific growth rates for P-limited S. fluviatilis in the laboratory streams were inversely related to flow velocity when ambient PO4-3 was undetectable. However, growth was not diminished at the fastest velocity when PO4-3 was available for uptake. Thus, the increase in cellular phosphorus demand can be offset by flow-enhanced P uptake when conditions permit; otherwise, growth will be impaired. The optimum N:P ratios for S. fluviatilis at 3, 12, and 30 cm·s-1 were 50, 58, and 52 by atoms, respectively, when calculated for PSnet=0. The optimum ratios were inversely related to PSnet and decreased to approximately 20 when PSnet was near maximum. The potential for flowing water to mediate nutrient partitioning among lotic algae by altering growth rates and optimum nutrient ratios is discussed.

Borchardt, MA, Hoffman, JP, and Cook, PW. 1994. Phosphorus uptake kinetics of Spirogyra fluviatilis Charophyceae in flowing water. Journal of Phycology 30(3):403-417.

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The inorganic phosphorus (Pi) uptake kinetics of Spirogyra fluviatilis Hilse were examined as a function of phosphorus cell quota (QP) and flow velocity in a laboratory stream apparatus. Short-term uptake and the acclimation of the uptake mechanism to flow were measured by the disappearance of Pi pulses in a recirculating flow cell. Short-term Pi uptake was biphasic. When the alga was P-deficient, Phase 1 and 2 half-saturation constants and maximum uptake rates were 11.0 and 47.2 μg P·L−1 and 473 and 803 μg P·g dry wt−1 h−1, respectively. Flowing water altered short-term uptake when the alga was P-deficient, but not when it was P-replete. When QP was less than 0.21%, increases in flow velocity from 3 to 15 cm·s−1 enhanced uptake with maximum uptake for any Pi pulse at 12 and 15 cm·s−1. At 22 and 30 cm·s−1, uptake was reduced by 12% or more relative to the maxima. If, however, the alga was cultivated at 22 and 30 cm·s−1 and short-term Pi uptake was measured at 12 cm·s−1, uptake was on average 33% greater than when the alga was cultivated at the latter velocity. Apparently, the alga could adjust short-term uptake to compensate for the suboptimal conditions of the faster velocities. Long-term Pi uptake and net phosphorus efflux were estimated by a non-steady state application of the Droop equation. Long-term uptake of very low Pi concentrations was not reduced by fast flowing water. Instead, uptake increased proportionately with flow velocity. Maximum phosphorus efflux from S. fluviatilis was 3% of cellular P per hour and occurred when QP was greater than 0.2%. At lower QP, the hourly efflux rate was typically less than 1%. Flowing water did not greatly enhance efflux, although when Pi was undetectable, efflux did tend to increase slightly with velocity. The data show that the effects of flowing water on Pi uptake were varied and not always beneficial. If the effects of flowing water on nutrient acquisition by other lotic algae are similarly varied and complex, flow may be an important determinant of nutrient partitioning among benthic algae in streams.

Douglas, WC, McIntosh, A, Clausen, JC. 1993. Toxicity of sediments containing atrazine and carbofuran to larvae of the midge Chironomus tentans. Enviromental Toxicology and Chemistry 12(5):847-853.

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Field and laboratory tests were conducted to determine the 10-d toxicity of atrazine and carbofuran to larvae of the midge Chironomus tentans. The pesticides were first spiked onto a clean control sediment, and the midges were exposed to atrazine, carbofuran, or mixtures of both compounds. Laboratory toxicity tests with carbofuran yielded LC50s of 20.5 μg/kg bound to sediment and 11.8 μg/L dissolved in interstitial water. Slight but statistically significant toxicity was detected at the highest tested concentration of atrazine (9,000 μg/kg, bound). Toxic interaction between the two pesticides was assessed using all possible combinations of four concentrations of both pesticides spiked onto clean sediments. Analysis of variance was used to determine if greater than or less than additive effects occurred when both pesticides were present. No toxic interaction between atrazine and carbofuran was detected. Based on laboratory findings, it was predicted that edge-of-field runoff could be toxic to midge larvae if concentrations of carbofuran exceeded 5 μg/kg. To test these predictions, actual edge-of-field runoff was collected from a cornfield receiving atrazine and carbofuran at recommended rates and the suspended sediments used in a toxicity test. Edge-of-field runoff containing carbofuran at 186 μg/kg was acutely toxic to midge larvae.

Duchovnay A, JW Reid, A McIntosh. 1992. Thermocyclops crassus (Crustacea: Copepoda) present in North America: a new record from Lake Champlain. J. Great Lakes Res. 18: 415-419.

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The cyclopoid copepod Thermocyclops crassus was collected in Missisquoi Bay, LakeChamplain, Vermont, U.S.A., in May and August 1991. Since this is the first confirmed record of the species in North America, the population is considered to be introduced. Thermocyclops crassus is widespread in temperate and tropical Eurasia and Africa, but, in the Americas, has been collected previously only in Costa Rica. It is planktonic and thermophilic, with a preference for eutrophic waters.

Shellinger, GR and Clausen, JC. 1992. Vegetative filter treatment of dairy barnyard runoff in cold regions. Journal of Environmental Quality 21(1):40-45.

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A vegetative filter strip was installed to treat barnyard runoff from an active dairy farm in Vermont. Runoff from a concrete surfaced barnyard flowed through a detention pond, then onto a vegetative filter strip measuring 22.9 m by 7.6 m with a 2% slope. The water input and surface and subsurface outputs for the strip were continuously monitored from December 1984 through May 1986. Of the total barnyard runoff entering the strip, 65% left as surface runoff and 27% was measured as subsurface outflow. The average hydraulic loading rate was 14.7 cm wk-1 and the average overland flow detention time was 15 min. The filter strip did not significantly (P < 0.05) reduce solids, P, N and bacteria concentrations in the surface output. Over the period of study the mass retention was 33% total suspended solids, 12% total P and 18% total Kjeldahl N. Mass retention was highest during the growing season and was poorest during snowmelt periods. It was concluded that poor filter strip performance was due to an excessive hydraulic loading rate resulting in an inadequate detention time for proper treatment. A preferential flow path from the level lip spreader to the subsurface drain tiles may have contributed to the poor subsurface treatment performance.

Watzin, MC. 1992. A research and monitoring agenda for Lake Champlain : proceedings of a workshop, December 17-19, 1991, Burlington, Vermont. Lake Champlain Basin Program technical report 1.

Brynn, DJ and Clausen, JC. 1991. Postharvest assessment of Vermont's acceptable silvicultural management practices and water quality impacts. Northern Journal of Applied Forestry 8(4):140-144.

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Seventy-eight recently completed timber harvesting operations in Vermont were evaluated for Acceptable Management Practice (AMP) compliance, soil erosion extent, and water quality impacts using a systematic, one-day examination of each site. Evaluations of water quality impacts and soil erosion were conducted on the portions of the transportation network and streams that could be most heavily affected by the timber harvesting operation. Increased stream sedimentation was observed on 46% of the operations with streams. Woody debris impacts occurred on 65% of the operations with streams. AMP compliance was over 90% for protective strip maintenance and stream avoidance, but soil erosion control practices on truck roads and skid trails commonly failed to meet AMP recommendations. Soil erosion was very limited on truck roads, skid trails, and log landings. Although the Vermont operations often only partially complied with the AMPs, minimal soil erosion and water quality impacts were observed.

Kirn, RA and LaBar, GW. 1991. Stepped-oblique midwater trawling as an assessment technique for rainbow smelt. North American Journal of Fisheries Management 11:167-176.

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Discrete-depth midwater trawling for rainbow smelt Osmerus mordax at night in Lake Champlain revealed a delayed vertical migration of smaller fish and size partitioning vertically within the water column. These behavioral observations led to the development and evaluation of a nighttime stepped-oblique midwater trawling technique. This latter method proved effective in obtaining large catches of rainbow smelt (mean catch per unit of effort [CPUE], 215-655 fish/ 55-min trawl) and provided estimates of relative abundance with reasonable precision (CPUE ± 13-50% from June through October), as well as estimates of length and age distributions unbiased by vertical migration behavior.

Clausen, JC and Johnson, GD. 1990. Lake level Influences on sediment and nutrient retention in a lakeside wetland. Journal of Environmental Quality 19(1):83-88.

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Lake levels, sediment and nutrient retention, and flows were studied in a 180-ha wetland adjacent to Lake Champlain, VT, to assess the role of lake levels on sediment and nutrient retention within the wetland. This wetland received both point and nonpoint sources of nutrients. Input, output, and within-wetland water samples were collected at 15 sites, and flows were measured nine times in 1983 at lake levels varying over 2 m. The ratio of wetland inflow to outflow was related to changes in lake levels. During spring, the concentrations of total suspended solids, total P, and total Kjeldahl N throughout the wetland were lower than during summer and fall periods. Wetland outlet concentrations decreased with rising lake levels. When wetland inflows exceeded outflow, there was a net mass retention of total suspended solids, total P, and total Kjeldahl N. Exports from the wetland decreased as lake level increased. The sediment and nutrient treatment capacity of this lakeside wetland appeared to be dominated by hydrologic influences.

Davis, LS, Hoffman, JP, and Cook, PW. 1990. Production and nutrient accumulation by periphyton in a wastewater tretment facility. Journal of Phycology 26(4):617-623.

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Five growth experiments were conducted over a 15-month period to quantify biomass, seasonal growth rates, and production of a periphyton community in the secondary clarifier of a wastewater treatment plant. A maximum periphyton biomass of 130 g·m-2 (ash-free dry weight) was achieved during fall. Growth rates of approximately 0.23·d-1 (from chlorophyll a) were observed during spring, summer and fall. Winter values were also high (0.20·d-1). Maximum production was approximately 22 g·m-2·d-1 during spring. Periphyton phosphorus and nitrogen content was variable ranging from 0.4-2.4 and 4.4-15.1%, respectively. Estimated maximum removal rates of both nutrients were high (up to - 160 mg P·m-2·d-1 and - 1900 mg N·m-2·d-1). High productivity and nutrient removal rates in this lotic hypereutrophic ecosystem may warrant further investigation of periphyton as a tertiary biological wastewater treatment in cold climates.

Davis, LS, Hoffman, JP, and Cook, PW. 1990. Seasonal succession of algal periphyton from a wastewater treatment facility. Journal of Phycology 26(4):611-617.

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Attached algal populations were sampled at weekly or biweekly to characterize successional changes in the secondary clarifiers of a wastewater treatment plant. Three communities were compared from areas of slow, medium and rapid current velocities. In general, the algae resembled those reported for other hypereutrophic flowing water. Of the twenty-three algae recorded, Stigeoclonium, Oedogonium, Oscillatoria, Lyngbya, and Pleurocapsa were dominant at some point in the 15 month sampling period. Nutrient concentrations were consistently high (N = 1.1-21.4 mg·L-1; P = 0.1-10.4 mg·L-1); therefore, changes in temporal distribution of algae were probably dependent on seasonal changes in light and temperature. Colonization of artificial substrates was also observed. Small unicellular algae were the first autotrophs to attach and these were followed by larger filamentous forms.

Ross, DS and RJ Bartlett. 1990. Effects of Extraction Methods and Sample Storage on Properties of Solutions Obtained from Forested Spodosols. Journal of Environmental Quality 19(1):108-113.

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Soil solutions obtained by three methods from Spodosols at a high-elevation, forested study site were compared. Solutions were extracted by miscible displacement, by centrifugation, and by compressing a soil-packed syringe. Analyses of pH, inorganic anions, total and reactive Al, and organic C showed few differences between miscible displacement and the syringe-pressure methods. However, centrifugation at a relative centrifugal force (RCF) of 9700 m s-2 consistently produced solutions with significantly higher pH and F- content than did the other methods. Differences after centrifugation also were found in Cl-, NO-3, SO2-4, but Al, but less frequently. Effect of soil storage time on solutions obtained using the syringe-pressure technique was studied. Both Oa and Bhs horizon samples showed large increases in solution NO-3 after 24 h of storage at 3 degrees C. During 36 d of storage, NO-3 levels increased by as much as 10-fold and were accompanied by pH decreases. Measurements in solutions obtained from samples that had been frozen for 36 d were higher than in the original solutions, except for NO-3 and pH. Changes with freezing appeared to be related to large increases in soluble organic C. Our results suggest that soil solution samples should be obtained very quickly after sampling of soils and that high-speed centrifuge techniques may give erroneous results. The syringe-pressure method is relatively rapid, simple, and easily performed in the field. However, it may not be practical under dry conditions.

Clausen, JC and Meals, DW. 1989. Water quality achievable with agricultural best management practices. Journal of Soil and Water Conservation 44(6):593-596.

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Greater emphasis has been placed on controlling nonpoint sources of pollution; however, the quality of water achieved by implementing best management practices (BMPs) remains uncertain. Water quality in runof from agricultural areas under best management was compared with water quality standards, where appropriate, and with other measures of treated water, thereby defining the water quality achievable by using best management practices. f i e study draws upon results obtained from 7 years of water quality monitoring in the LaPlatte River and St. Albans Bay watersheds in kmont of BMPs implemented for manure management, barnyard rune$ and milkhouse wastes. These studies include long-term stream monitoring for sediment and nutrient concentration and load, as well as intensive evaluation of the treatment efectiveness of certain BMPs, such as vegetated filter strips and manure storage, on concentration and export of sediment, nutrients, and bacteria. Results indicate that BMPs may be highly effective in reducing pollutant concentrations and loads, but runof may continue to exceed water quality criteria. Further development of BMPs is needed to improve the water quality achievable.

Schwer, CB and Clausen, JC. 1989. Vegetative filter treatment of dairy milkhouse wastewater. Journal of Environmental Quality 18(4):446-451.

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A vegetated filter strip constructed to treat milkhouse wastewater from a Vermont dairy farm was evaluated to determine its effectiveness in reducing solids, P and N concentrations and exports in surface and subsurface flow. The liquid waste was applied twice daily via a level lip spreader at a rate of 2.94 cm/wk on a vegetated loam soil having a 2% slope. The flow and concentrations of inputs and surface and subsurface outputs were continuously monitored during the 2-yr study. The strip significantly (P < 0.01) reduced solids, P, and N on a concentration basis, and retained 95% solids, 89% P, and 92% N on a mass basis. Retention was the greatest during the growing season and the poorest during snowmelt periods. Concentrations in subsurface outputs were greater than in surface runoff and over 75% of the mass export was in subsurface flow. Comparisons of this study with values reported in the literature suggests that hydraulic loading rate governs the effectiveness of filter strip treatment.

Ratsep, AI and Sjogren, RE. 1984. Assay for biologicaly available phosphorus using proteolytic Aeromonas hydrophila. Freshwater Biology14:423-429.

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1. A simple and inexpensive assay was developed to determine the amount of biologically available phosphorus (BAP) present in freshwater.
2. BAP was measured by using Aeromonas hydrophila in a proteolytic assay system in which the release of the chromogen from an insoluble azure dye derivative of hide powder (HPA) was determined spectrophotometrically. The time necessary to hydrolyse 50% of the HPA was found to be directly dependent on the amount of BAP present. BAP within the range 2-250 µg 1-1 phosphate-phosphorus was detected.
3. Our data suggest that the application of this assay for the measurement of BAP in freshwater offers the potential of monitoring the biological response of a freshwater ecosystem to phosphorus.

Hopkins, RB and Clausen, JC. 1983. Land use monitoring and assessment for nonpoint source pollution control. Perspectives on Nonpoint Source Pollution, Proceedings of a National Conference, Kansas City MO. May 19-22, 1985. Environmental Protection Agency, 1985. p 25-29.

Ciali, CP and Manning, RE. 1981. Recreation and River Type: Social-Environmental Relationships. Environmental Management 5(2): 109-120.

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Recreation use was studied on a diverse state river system to test the hypothesis that recreation use patterns vary systematically by river type. River segments were classified into representative river types through application of a two-reid classification system. The first classification factor, generalized geomorphology, defines and groups the dominant resource bases of which rivers are comprised. The second classification factor, cultural setting, defines the land use and settlement patterns in which each river type is found. Significant differences were found among resulting river types with respect to the nature and intensity of recreation activity, desired use density, and user perceived problems and conflicts. Management recommendations were developed, based on study findings, for each river type. It is concluded that when both environmental attributes and cultural setting are taken into account, regularities appear with respect to the way in which river resources are used and perceived by recreationists. Further exploration and expansion of such recreation-resource relationships to other activities and environments may hold substantial implications for the allocation and management of outdoor recreation resources.

Sjogren, RE and Gibson, MJ. 1981. Bacterial survival in a dilute environment. Applied Environmental Microbiology 41(6):1331-1336.

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Bacteria were isolated from lake water, and their ability to remain viable in a dilute, nutrient-deficient environment was tested by a method that permits suspension of test bacteria between two appressed microporous membranes in an aqueous environment. This approach permitted separation of the lake isolates into two categories. Members of the tribe Klebsielleae were shown to have a prolonged survival rate of 40% or better after 24 h, whereas nonsurvivors were not viable for much longer than 24 h. These nonsurvivors belonged to the genera Acinetobacter, Aeromonas, Alcaligenes, Erwinia, Escherichia, Flavobacterium, and Pseudomonas. Differences in ribonuclease and adenosine triphosphatase levels between Escherichia coli (nonsurvivor) and Klebsiella (survivor) cells were detected. At pH 7.5, stressed E. coli cells contained 14% of the adenosine triphosphatase activity detected in the control, whereas at pH 5.5, in the presence of calcium ions, these same cells contained 50% of the control adenosine triphosphatase levels. At pH 7.2, E. coli cells were strongly inhibited by an adenosine triphosphatase inhibitor, bathophenanthroline (88%); oligomycin (64%); and the proton ionophore carbonyl- cyanide-m-chlorophenyl hydrazone (67%). Both sodium azide and valinomycin were only moderately inhibitory (15 and 28%, respectively). Although the ability to scavenge internal endogenous reserves seems important, we postulate that certain enteric bacteria are capable of utilizing acidic conditions (pH 5.5) as an electrochemical gradient to generate necessary high-energy intermediates for prolongation of survival beyond that possible in environments of near-neutral pH.

Sjogren, RE and Port, J. 1981. Heavy metal-antibiotic resistant bacteria in a lake recreational area. Water, Air, and Soil Pollution 15:29-44.

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We undertook this study to determine the impact of urbanization on the microbial content of waters of a major recreational area of Lake Champlain. We followed changes in the numbers of total coliforms, fecal coliforms, fecal streptococci, and ascertained resistance of coliforms to heavy metals and antibiotics. We determined the distribution of these bacterial indicators of pollution by examining water and sediment samples. We also surveyed changes in physical parameters such as pH, temperature, turbidity, and wind direction to evaluate their effect on the examined aquatic microbial population. The level of all standard microbial indices of pollution frequently exceeded acceptable levels for recreational waters. Sediment samples indicated prolonged deposition of microbial pollutants, but efforts to demonstrate their release from sediment by dislocation and resuspension were inconclusive. We confirmed the presence of a population of heavy-metal and antibiotic-resistant coliforms isolated from harbor waters. Eighty-four percent of the total coliforms isolated from harbor water samples were resistant to one or more antibiotics and 96% were resistant to two or more heavy metals. The presence of these antibiotic resistant properties in coliforms, as well as elevated fecal coliform and fecal streptococci counts in both water and sediment samples, suggests to us that the bay is polluted by human fecal matter. This pollution probably emanates from south harbor sources and affects the shores of the major northern bathing area. It constitutes a potential hazard to public health because of the geophysical nature of the harbor and the location of the pollution source.

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