SPATIAL DELINEATION OF BIOTIC AND ABIOTIC GRADIENTS IN A RURAL NEW YORK RESERVOIR1

ABSTRACT: The spatial changes in abiotic and biotic variables from riverine to lacustrine areas characterized by the river-lake concept of reservoir function was applied to the Tomhannock Reservoir, Rensselaer County, New York. To identify these longitudinal gradients, a two-year investigation (May 1991 to October 1992) was conducted to measure primary productivity, nutrient concentrations, chlorophyll α and phytoplankton biomass at three locations in the 705-ha water supply reservoir. Emphasis was placed on the measurement of primary production using the carbon-14 artificial incubator (photosynthetron) technique. The average annual production in 1992 was 247.3 gm^?2 245 d^?1, ranging from 52 to 2677 mg C m^?2. Mean alpha^B (assimilation efficiency), P^Bm (assimilation number), and I_k (saturation irradiance) were 4.40 mg C mgChl^?1 E^?1 m^?2, 3.82 mg C mgChl^?1 h^?1, and 236.5 μE m^?2 s^?1, respectively. Neither seasonal nor spatial variability of these photosynethetic parameters were observed. Except for Secchi depth, distinct longitudinal zones from river inflow to darn were not statistically demonstrated in the Tomhannock Reservoir. Mean extinction coefficient, chlorophyll α and total phosphorus concentrations decreased; Secchi transparency and phytoplankton biomass increased; while primary productivity and dissolved inorganic nitrogen concentration remained the same from headwater to darn. These baseline data will be used to assess the future effectiveness of best management practices (BMPs) recently instituted on selected watershed farmland in an attempt to reduce the detrimental impact of agricultural activities on drinking water quality.     

The environmental impact of a chloro-alkali factory in a river basin in Eastern India

Summary It has been established that the electrodes of the dialyser in a chloro-alkali plant in Eastern India release mercury beyond the permissible limits into the River Koel. Mercury in elemental form, as well as certain organo-mercury compounds, including methyl mercury, have been detected at a distance of 25 km from the discharge point. Even at a distance of 5–10 km, the mercury content of the sediment may be as high as 0.6–3.2 mg kg^–1 above the value of sediment upstream of the plant. This sediment itself is contaminated, probably by battery and paint factories, etc., still further upstream. Thus, the chloro-alkali factory has contributed 60–320 times above the permissible limit (0.01 mg kg^–1) of mercury release, at a distance of 5–10 km from the point of release. Furthermore, various phytoplankton and zooplankton have been contaminated, leading to very high mercury contents in certain fish. This food chain, therefore, threatens man himself.Dr Sajalendu Nanda is currently a Research Associate at Bangur Institute of Neurology in Calcutta. He possesses an MSc in Environmental Biology and a PhD in Ecology. His address for correspondence is c/o Dr P.K. Tapaswi, Professor-in-Charge at the Biological Sciences Division of the Indian Statistical Institute.     

ISOTOPIC EVALUATION OF Pb OCCURRENCES IN THE RIVERINE ECOSYSTEMS OF THE KANKAKEE WATERSHED,ILLINOIS‐INDIANA1

ABSTRACT: Environmental background levels of Pb were measured in ponds, river waters, sediments, suspended sediments, rocks, and air particulates within the Kankakee watershed during the period of 1995 to 1999. Stable isotopic Pb distinguished airborne Pb and its incorporation into riverine wetland sediments from geogenic Pb measured in river sediments. The provenance of the naturally‐occurring Pb is from carbonate bedrock and contributes comparable concentrations in riverbank sediments (25.9–30.4 mg kg^?1) as Pb found in wetland sediments (18.6–24.8 mg kg^?1). Estimates of anthropogenic Pb contributions from airfall into the Kankakee wetlands were found to be near 0.43–0.71 Bq cm^?2 yr^?1 during 1995 to 1999. While leachable Pb data suggests the uppermost layers of pond sediments were disturbed, ²¹⁰Pb analyses from undisturbed sedimentation suggests Pb‐bearing sediments accumulate approximately 0.46–0.51 cm yr^?1 in the ponds within the riparian zones. Transboundary Pb pollution from aerosols of industrial Pb across the Great Lakes occurs, but Pb isotopy indicates that the Pb concentrations are comparable to natural concentrations of Pb in both waters and sediments within the Kankakee watershed.     

Clogging of an Effluent Dominated Semiarid River: A Conceptual Model of Stream‐Aquifer Interactions1

Abstract: Water managers in arid and semiarid regions increasingly view treated wastewater (effluent) as an important water resource. Artificial recharge basins allow effluent to seep into the ground relieving stressed aquifers, however these basins frequently clog due to physical, chemical, and biological processes. Likewise effluent is increasingly used to maintain perennial base flow for dry streambeds, however, little is known about the impact of effluent on streambed hydraulic conductivity and stream‐aquifer interactions. We address this issue by investigating: if a clogging layer forms, how the formation of a clogging layer alters stream‐aquifer connections, and what hydrologic factors control the formation and removal of clogging layers. We focused on the Upper Santa Cruz River, Arizona where effluent from the Nogales International Waste Water Treatment Plant sustains perennial flow. Monthly sampling, along a 30 km river reach, was done with two foci: physical streambed transformations and water source identification using chemical composition. Historical dataset were included to provide a larger context for the work. Results show that localized clogging occurs in the Upper Santa Cruz River. The clogging layers perch the stream and shallow streambed causing desaturation below the streambed. With these results, a conceptual model of clogging is established in the context of a semiarid hydrologic cycle: formation during the hot premonsoon months when flow is nearly constant and removal by large flood flows (>10 m³/s) during the monsoon season. However, if the intensity of flooding during the semiarid hydrologic cycle is lessened, the dependent riparian area can experience a die off. This conceptual model leads us to the conclusion that effluent dominated riparian systems are inherently unstable due to the clogging process. Further understanding of this process could lead to improved ecosystem restoration and management.     

A SCALED HYDRAULIC MODEL OF THE PEACH BOTTOM ATOMIC POWER STATION DISCHARGE1

ABSTRACT: A scaled hydraulic model was used as a schematic representation of the Peach Bottom Atomic Power Station (PBAPS) discharge into Conowingo Pond during critically low river flows. The model approximated flow and temperature patterns and the degree of recirculation are assessed. Under normal operation the effluent is carried downstream and dissipated within about two miles. However, during dry weather years, river inflows can decrease substantially, resulting in unknown recirculation of effluent and flow patterns in Conowingo Pond. This study was conducted to investigate and predict flow patterns in Conowingo Pond under critically dry weather conditions. A threshold river flow is also identified that indicates a measure of the river's ability to maintain downstream advection of the effluent. The study suggests a number of unexpected current patterns, potential recirculation of the effluent, and changes in the dilution of the effluent.     

Fish bioassay monitoring of waste effluents

Spills of toxic materials into bodies of water receiving industrial waste discharges can be prevented only if frequent or continuous assessments of effluent quality can be made. Currently available methods can automatically measure individual physical or chemical waste components but cannot assess toxicity caused by the interaction of components or the presence of an unsuspected material. Aquatic organisms, in contrast, respond to their total environment and in this way integrate the effects of all the various chemical and physical waste parameters.This study evaluates the possibility of using the continuously and automatically recorded responses of fish to monitor the toxicity of industrial waste effluents. A review of previously developed toxicity monitoring systems is followed by a field evaluation of a method that uses the computer-monitored ventilatory patterns of 12 bluegills (Lepomis macrochirus Rafinesque) to monitor the toxicity of an industrial waste effluent as it flows into a river. No known toxic spills occurred in the effluent during the operation of this system, but acetone added to the effluent waste caused responses from the fish at concentrations which peaked near the 96-hr LC₅₀ level. Some responses were also noted when no known toxicant was present; these were related to environmental disturbances and system design problems. Recommendations are made for the design of future biologic monitoring units.     

Removing color and chlorinated organics from pulp mill bleach plant effluents by use of flyash

Color and chemical oxygen demand (COD) in bleach plant effluents are of concern. Acidified flyash can effectively remove both color and COD from caustic bleach plant effluents. Equally effective, but quicker and easier, is to acidify the effluent to approximately pH 1 and use untreated flyash. Based on maximum color removal, the required contact time is short, about 10 min, and the optimum ash dosage is that amount which raises the pH of the final effluent to about 5. Sufficient color removal is obtained to easily meet Maine's color regulations. Preliminary tests on samples of deionized water spiked with two arochlors of PCB showed high removal efficiency.The major cost of implementing and operating the cleanup procedure will be the cost of the required acid. This might be minimized by using some of the acidic (chlorine) effluent to lower the pH of the caustic effluent. This will, however, lead to less color reduction, and an unknown effect on the COD.     

Environmental Impact Assessment of Sand Mining from the Small Catchment Rivers in the Southwestern Coast of India: A Case Study

In the past few decades, the demand for construction grade sand is increasing in many parts of the world due to rapid economic development and subsequent growth of building activities. This, in many of the occasions, has resulted in indiscriminate mining of sand from instream and floodplain areas leading to severe damages to the river basin environment. The case is rather alarming in the small catchment rivers like those draining the southwestern coast of India due to limited sand resources in their alluvial reaches. Moreover, lack of adequate information on the environmental impact of river sand mining is a major lacuna challenging regulatory efforts in many developing countries. Therefore, a scientific assessment is a pre-requisite in formulating management strategies in the sand mining-hit areas. In this context, a study has been made as a case to address the environmental impact of sand mining from the instream and floodplain areas of three important rivers in the southwestern coast of India namely the Chalakudy, Periyar and Muvattupuzha rivers, whose lowlands host one of the fast developing urban-cum-industrial centre, the Kochi city. The study reveals that an amount of 11.527 million ty⁻¹ of sand (8.764 million ty⁻¹ of instream sand and 2.763 million ty⁻¹ of floodplain sand) is being mined from the midland and lowland reaches of these rivers for construction of buildings and other infrastructural facilities in Kochi city and its satellite townships. Environmental Impact Assessment (EIA) carried out as a part of this investigation shows that the activities associated with mining and processing of sands have not only affected the health of the river ecosystems but also degraded its overbank areas to a large extent. Considering the degree of degradation caused by sand mining from these rivers, no mining scenario may be opted in the deeper zones of the river channels. Also, a set of suggestions are made for the overall improvement of the rivers and its biophysical environment.     

Analysis of Sediment Retention in Western Riverine Wetlands: The Yampa River Watershed,Colorado, USA

We quantified annual sediment deposition, bank erosion, and sediment budgets in nine riverine wetlands that represented a watershed continuum for 1 year in the unregulated Yampa River drainage basin in Colorado. One site was studied for 2 years to compare responses to peak flow variability. Annual mean sediment deposition ranged from 0.01 kg/m² along a first-order subalpine stream to 21.8 kg/m² at a sixth-order alluvial forest. Annual mean riverbank erosion ranged from 3 kg/m-of-bank at the first-order site to 1000 kg/m at the 6^th-order site. Total sediment budgets were nearly balanced at six sites, while net export from bank erosion occurred at three sites. Both total sediment deposition (R² = 0.86, p < 0.01) and bank erosion (R² = 0.77, p < 0.01) were strongly related to bankfull height, and channel sinuosity and valley confinement helped to explain additional variability among sites. The texture and organic fraction of eroded and deposited sediment were relatively similar in most sites and varied among sites by watershed position. Our results indicate that bank erosion generally balances sediment deposition in riverine wetlands, and we found no distinct zones of sediment retention versus export on a watershed continuum. Zones of apparent disequilibrium can occur in unregulated rivers due to factors such as incised channels, beaver activity, and cattle grazing. A primary function of many western riverine wetlands is sediment exchange, not retention, which may operate by transforming materials and compounds in temporary sediment pools on floodplains. These results are considered in the context of the Hydrogeomorphic approach being implemented by the U.S. government for wetland resource management.     

Phosphorus concentrations, loads, and sources within the Illinois River drainage area, northwest Arkansas, 1997-2008

In the Ozark Highlands and across the United States, effluent phosphorus (P) sources often have a profound impact on water column concentrations and riverine transport. This study evaluated (i) annual P loads at the Illinois River at Arkansas Highway 59 from calendar year 1997 through 2008, (ii) the relative contribution of effluent P sources to annual riverine P transport, (iii) longitudinal gradients in water column P concentrations downstream from several wastewater treatment plant effluent discharges, and (iv) changes in monthly P loads over the last decade. This study showed that annual P loads have ranged from 64,000 kg to over 426,000 kg and that P transport was positively correlated to hydrology (i.e., the amount of water delivered downstream). The relative contribution of P inputs from municipal facilities has decreased from 40% of the annual P load at the Illinois River at Arkansas Highway 59 to < 15% in recent years. Elevated P concentrations during base flow conditions were traced 45 river km upstream to one municipal effluent discharge, but all effluent discharges influenced P concentrations in the receiving streams. Most important, flow-adjusted monthly P loads showed two distinct trends over time. Flow-adjusted loads significantly increased from 1997 through 2002 and significantly decreased from 2002 through 2008. The concentrations and transport of P within the Illinois River drainage area are significantly decreasing from all the watershed management changes that have occurred, and monitoring should continue to determine if this decrease continues at the same rate over the next several years.     

Does improved waste treatment have demonstrable biological benefits?

Since 1972, 10 benthic surveys and 9 static fish bioassays have been conducted to assess the impact of AVTEX Fibers, Inc. effluent on the lower South Fork of the Shenandoah River. AVTEX (formerly FMC Corp.) is a rayon and polyester fibers plant located in Front Royal, Virginia. Benthic samples were taken at four stations, one above and three below the plant discharges. Single surveys in 1972 and 1973 indicated a severe impact on the benthic community along the right side of the river, below the plant, as a result of the channelized effluent. Diversity values (¯d) were low (0–2.42) and numbers of taxa and organisms were reduced. A fish bioassay in 1973 indicated the effluent to be acutely toxic at the 34.5% level (mixture of effluent and river water). In early 1974, FMC Corp. constructed an activated sludge treatment system to reduce BOD and supplement the neutralization and chemical precipitation (zinc hydroxide and liquid-solid separation) facilities that had been used to treat waste waters since 1948. After the new equipment was placed in operation, the previously stressed area became more stable. In 1975 and 1976 the stressed area exhibited greater ¯d values (1.19–3.39) and an increased number of taxa and organisms. Bioassays showed the effluent to be acutely toxic to fish only once since 1973. The major improvements in the effluent were a 70% reduction in BOD₅ and a 60% reduction in the amount of zinc entering the river. Community conditions in 1977 indicated a partial remission of improvement, probably due to drought conditions.The rehabilitation of damaged ecosystems is a process important to all biologists. An important factor in encouraging industry to participate in this activity is evidence that improved waste treatment will often have demonstrable biological benefits rather soon. As data accumulate on the recovery process it may be possible to predict the degree of rehabilitation and time required more precisely.     

Microalgae‐based biodiesel production in open raceway ponds using coal thermal flue gas: A case of West Bengal,India

India is one of the most populous countries and is the third largest greenhouse gas–emitting nation. Energy security is a serious issue for India as it relies heavily on fossil fuel imports. Biodiesel production using microalgae as feedstock can address both of these issues. In this study, the technical feasibility of microalgae‐based biodiesel production is carried out for a coal thermal power plant (i.e., Budge Budge Thermal Station) in the state of West Bengal, India, using a generic methodology. An oleaginous microalgae species that is tolerant toward flue gas was identified (i.e., Nannochloropsis sp). A 75‐acre open raceway microalgae production plant was designed keeping the costs, energy demand, and CO₂ emissions low. The open raceway pond can use 38 tons of CO₂, produce 19 tons of algal biomass, and treat 9320 m³ of wastewater per acre annually.     

Investigating the quantitative and qualitative status of effluent in the wastewater treatment plant in Iran Central Iron Ore

The aim of present study was to investigate the quality of the produced effluent from different units of the Iran Central Iron Ore in Bafq city and comparison of effluent with the standards. This study presents the physicochemical and biological parameters data of effluent of three Sequencing batch reactors (SBR) with a capacity of 160 m³?d^?1. Most common parameters include pH, total suspended solids (TSS), total nitrogen (TN), total phosphorus (TP), biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), heavy metals, and total coliforms and fecal coliforms as biological indicators. Then, for each SBR system, the average of each parameter was determined, and results were compared with the standard recommended by the Iranian Environmental Protection Agency. Based on the results, some of the parameters, including BOD₅, COD, and TSS in the wastewater treatment plant (WWTP) effluent, are higher than the permitted amount for discharge to the surface water. Considering the BOD₅, COD, and TSS concentration in WWTPs, the treated wastewater is only suitable for agricultural and irrigation use. Therefore, wastewater produced by Iran Central Iron Ore Co. will need additional treatment to achieve standard quality of water before discharge in surface water and adsorbent well.     

Spatiotemporal Variability in Water Sources Controls Chemical and Physical Properties of a Semi‐arid Urban River System

We conducted synoptic surveys over three seasons in one year to evaluate the variability in water sources and geochemistry of an urban river with complex water infrastructure in the state of Utah. Using stable isotopes of river water (δ¹⁸O and δ²H) within a Bayesian mixing model framework and a separate hydrologic mass balance approach, we quantified both the proportional inputs and magnitude of discharge associated with “natural” (lake, groundwater, and tributary inputs) and “engineered” (effluent and canal inflows) sources. The relative importance of these major contributors to streamflow varied both spatially and seasonally. Spatiotemporal patterns of dissolved oxygen, temperature, pH, calcium, chloride, nitrate, and orthophosphate indicated seasonal shifts in dominant sources of river water played an important role in determining water quality. We show although urban rivers are clearly influenced by novel water sources created by water infrastructure, they continue to reflect the imprint of “natural” water sources, including diffuse groundwater. Resource managers thus may need to account for the quantity of both surface waters and also historically overlooked groundwater inputs to address water quality concerns in urban rivers.     

Natural and Anthropogenic Methane Emission from Coastal Wetlands of South India

For the first time, the methane emissions from diverse coastal wetlands of South India have been measured. Annual emission rates varied widely, ranging from 3.10 mg/m²/hr (Bay of Bengal) to 21.56 mg/m²/hr (Adyar River), based on nature of the perturbance to each of the ecosystems studied. Distinct seasonality in methane emission was noticed in an unpolluted ecosystem (mangrove: 7.38 mg/m²/hr) and over a twofold increase was evident in the ecosystem that was disturbed by human activities (21.56 mg/m²/hr). The wide ranges in estimate suggest that methanogenesis occurs by both natural and anthropogenic activities in these coastal wetlands. Several physical and chemical factors such as salinity, sulfate, oxygen, and organic matter content influenced methanogenesis to a large degree in each of these ecosystems in addition to individual responses to human-induced stress. For example, there was a clear negative correlation between oxygen availability (0.99), sulfate (0.98), and salinity (0.98) with CH₄ emission in the Adyar river ecosystem. Although similar results were obtained for the other wetland ecosystems, CH₄ emission was largely influenced by tidal fluctuations, resulting in a concomitant increase in methanogenesis with high sulfate concentrations. This study demonstrates that coastal wetlands are potentially significant sources of atmospheric methane and could be a greater source if anthropogenic perturbations continue at the current rate. RID=" ID=" &ast;Author to whom correspondence should be addressed.     

Three Egyptian industrial wastewater management programmes

A pre-treatment programme for wastewater from factories, representing three main industrial sectors in Egypt, has been developed. The first case study was a factory producing potato-chips. Wastewater discharged from this factory was characterized by high values of BOD, SS and oil and grease (6000 mgO₂ l^–1, 6577 mg l^–1 and 119 mg l^–1 respectively). Chemical treatment using lime and lime aided by polyelectrolyte achieved good results. Residual values of BOD and SS after treatment were 97 mg l^–1 and 49 mg l^–1, respectively. Oil and grease concentrations were reduced by 91 percent. Treatment via activated sludge at a detention time of 4 hrs produced good quality effluent. The second case study was an automobile company, representing the metal finishing industry. Analyses of wastewater samples from the degreasing, phosphating and painting departments, as well as the end-of-pipe effluent were conducted. The end-of-pipe effluent contained high concentrations of oil and grease (366 mg l^–1), phosphorous (111 mg l^–1) and zinc (81 mg l^–1). Chemical treatment of end-of-pipe wastewater using ferric chloride aided by lime, produced high quality effluent. The third sector was the chemical industry. For this purpose a paint factory was selected. Characteristics of raw wastewater varied widely according to the production rate. Average values of COD and BOD were 1950 mg l^–1 and 683 mg l^–1. Oil and grease ranged from 63 to 1624 mg l^–1. Chemical treatment using ferric chloride in combination with lime at the optimum operating conditions achieved good results. Residual values after treatment of COD, BOD and oil and grease reached 120, 36 and 8.6 mg l^–1, respectively. An engineering design for each case study has been prepared.     

“Lean and Green” at a Romanian secondary tissue paper and board mill—putting theory into practice

A three-year environmental project was implemented at the Petrocart S.A. paper and board mill, through the Danish Support Programme for Eastern Europe (DANCEE). The aim was to use “Lean and Green” Production to improve industrial compliance with the effluent regulations and with EUs IPPC Directive under implementation in Romania, thereby improving the environmental conditions in the Bistrita River running through the town. The results obtained included an 87% reduction of the discharge of wastewater from 5300 to about 700 m³/day. Previously, the effluent was subjected to primary treatment only. The reduction in flow reduced mill fibre losses and allowed discharge to an existing, underloaded, municipal treatment system, where primary and secondary treatment is operated. Further results obtained were better housekeeping (5S and Kaizen) and a Total Quality Management (TQM) organisation was implemented where product quality, environment and occupational health and safety are merged into one system. Twenty-eight TQM groups were formed, each with a representative from management and elected among workers. The mill's employment is slightly higher today, and the gross turnover and profitability has almost tripled. Had Petrocart had the financial resources themselves carried the project through without DANCEE support, the payback time for the project would have been 3.7 years for the total of €2 million spent. Petrocart no longer pays penalties for environmental non-compliance. The performance contributes to IPPC-approval. The project was implemented within the framework of DANCEE's procedures, which is based on the Logical Framework Approach (LFA) for project management. The PRojects IN Controlled Environments (PRINCE2™) model for project management was also applied. This article analyses how the results were achieved and how Lean and Green thinking as well as good project management practices, such as LFA and PRINCE2 were applied to turn around an old Eastern European company to survive privatization.     

Application of best subset method for river water quality modeling: A study on Godavari River,India

The utilization of water quality analysis to inform optimal decision-making is imperative to achieve sustainable management of river water quality. A multitude of research works in the past has focused on river water quality modeling. Despite being a precise statistical regression technique that allows for fitting separate models for all potential combinations of predictors and selecting the optimal subset model, the application of best subset method in river water quality modeling is not widely adopted. The current research aims to validate the use of best subset method in evaluating the water quality parameters of the Godavari River, one of the largest rivers in India, by developing regression equations for different combinations of its physicochemical parameters. The study involves in formulating best subset regression equations to estimate the concentrations of river water quality parameters while also identifying and quantifying their variations. A total of 17 water quality parameters are analyzed at 13 monitoring sites using 13 years (1993–2005) of observed data for the monsoon (June–October) period and post-monsoon (November–February) period. The final subset model is selected among model combinations that are developed for each year's dataset through widely used statistical criteria such as R², F value, adjusted R²_a, AIC_c, and RSS. The final best subset model across all parameters exhibits R² values surpassing 0.8, indicating that the models possess the ability to account for over 80% of the variations in the concentrations of dependent parameters. Therefore, the findings demonstrated the appropriateness of this method in evaluating the water quality parameters in extensive rivers. This work is very useful for decision-making and in the management of river water quality for its sustainable use in the study area.     

ZOOPLANKTON COMMUNITIES OF A NEW PUMPED STORAGE RESERVOIR1

ABSTRACT: Zooplankton colonization was followed for 16 months in Lake Oconee, Georgia, a new pumped storage reservoir. Data were interpreted to identify differences among stations and seasons, as a function of the reservoir's early stage of development and of pumped storage operations. Colonization was rapid, and the zooplankton community was characterized by a high species diversity; approximately 40 rotifer species and 14 cladoceran genera were recorded. Zooplankton density varied along an environmental gradient from riverine to lentic conditions. Rotifer abundance varied from 10⁴-10⁶ individuals/m³, with maxima in the summers Copepod and cladoceran densities ranged from 10³ to nearly 10⁵ individuals/m³; maxima for stations other than the dam were observed in the summer and early fall, but high values at the dam station occurred throughout winter 1980. When pumped storage operations began in December 1979, zooplankton densities increased at the dam station. Pumpback decreased the intensity of the environmental gradient from riverine to lentic conditions, and led to a more similar zooplankton community structure throughout the reservoir.     

EFFECTS OF PLACER GOLD MINING ON PRIMARY PRODUCTION IN SUBARCTIC STREAMS OF ALASKA1

ABSTRACT: Turbidity, total residues, settleable solids, vertical light extinction, and primary production were measured in mined and unmined streams located in the interior highlands of Alaska. Undisturbed streams had low turbidities (< 1 NTU), total residue concentrations averaging 120 mg 1^?1, and undetectable settleable solids. During active mining, turbidity, total residues, and settleable solids levels in a moderately mined stream averaged 170 NTU, 201 mg 1^?1, and < 0.1 ml 1^?1, respectively. In a heavily mined stream, turbidity and total residues were two orders of magnitude higher than in unmined streams and settleable solids nearly always exceeded 0.2 ml 1^?1. Vertical extinction coefficients and turbidity were positively correlated. In undisturbed streams gross primary productivity (g-O₂m^?2d^?1) ranged from 0.20 shortly after spring breakup to a maximum of 1.20 in early fall. Productivity in the moderately mined stream was reduced by 50 percent while photosynthetic efficiency doubled. Primary production was undetectable in a heavily mined stream. Maximum standing crops of periphyton measured as chlorophyll a occurred in fall in an undisturbed stream after 13 weeks of exposure and ranged from 4.5 to 11.8 mg-chl a m^?2. The highest chlorophyll a densities recorded in the moderately mined stream was 3.8 mg m^?2, and no chlorophyl a was detected in the heavily mined stream.