Transport of lead and diesel fuel through a peat soil near Juneau, AK: a pilot study

A set of peat column experiments was used to determine the transport potential of lead (Pb) and diesel range organics (DRO) in palustrine slope wetlands near Juneau, AK. This project is important to southeast Alaskan communities because limited land resources are forcing development of regional wetlands. This study was instigated by concerns that proposed modifications to a nearby rifle range using DRO-contaminated soil posed a potential risk to an anadromous fish-bearing stream 250 m from the site. Three pairs of peat columns were extracted from the rifle range for analysis, one pair along and two pairs across the natural bedding planes of the soil. One column in each pair was spiked with Pb and DRO and the other was used as a control. Approximately 1-year worth of water (171 cm) was passed through each column and leachate was collected at regular intervals. The results showed that substantial DRO transport only occurred along the bedding planes. Leads was surprisingly mobile, both along and across the bedding planes with estimated soil-water partition coefficients several orders of magnitude lower than commonly published values, probably because the peat was heavily Pb-loaded by lead from bullets and because the peat's acidic, organic-rich environment enhanced Pb mobility. The chemical outflow behavior agreed with a simple macropore transport model. These results underscore the need for caution when developing regional wetlands.     

DECISION FRAMEWORK FOR SEDIMENT CONTROL IN MUDDY CREEK WATERSHED1

ABSTRACT: The tailwater of Bridgewater Dam, below Lake James, North Carolina, is a designated trout stream. It has environmental attributes for a good cold water fishery with the exception of high suspended sediments. Muddy Creek, a tributary about 1.5 km downstream of the dam, is a major source of sediments. The Muddy Creek Watershed Restoration Initiative was established to develop and implement a sediment control plan. The Watershed Analysis Risk Management Framework was applied to simulate soil erosion and sedimentation and to help determine appropriate action. The simulated sediment concentrations of the river were comparable to observed data from November 1994 to November 2001. For the base condition, the sediment load was 135,000 kg/d from surface erosion and 1,300,000 kg/d from bank erosion. Increasing the buffer strip from existing 50 to 80 percent to 100 percent of stream segments would only reduce surface erosion to 70,400 kg/d with little change in sediment concentrations. Eliminating riverbank erosion would reduce the sediment load from 920,000 to 87,700 kg/d. The bank stabilization project would not only lower suspended sediment concentrations for Muddy Creek, but also reduce the lake sediment accumulation in the downstream Lake Rhodhiss by approximately 13 percent.     

Cesium migration in Hanford sediment: a multisite cation exchange model based on laboratory transport experiments

Cs+ transport experiments carried out in columns packed with uncontaminated Hanford formation sediment from the SX tank farm provide strong support for the use of a multisite, multicomponent cation exchange model to describe Cs+ migration in the Hanford vadose zone. The experimental results indicate a strong dependence of the effective Cs+ Kd on the concentrations of other cations, including Na+ that is present at high to extremely high concentrations in fluids leaking from the Hanford SX tanks. A strong dependence of the Cs+ Kd on the aqueous Cs+ concentration is also apparent, with retardation of Cs+ increasing from a value of 41 at a Cs+ concentration of 10(-4) M in the feed solution to as much as 282 at a Cs+ concentration of 5x10(-7) M, all in a background of 1 M NaNO3. The total cation exchange capacity (CEC) of the Hanford sediment was determined using 22Na isotopic equilibrium exchange in a flow-through column experiment. The value for the CEC of 120 microeq/g determined with this method is compatible with a value of 121.9 microeq/g determined by multi-cation elution. While two distinct exchange sites were proposed by Zachara et al. [Geochim. Cosmochim. Acta 66 (2002) 193] based on binary batch exchange experiments, a third site is proposed in this study to improve the fit of the Cs+-Na+ and Cs+-Ca+ exchange data and to capture self-sharpened Cs+ breakthrough curves at low concentrations of Cs+. Two of the proposed exchange sites represent frayed edge sites (FES) on weathered micas and constitute 0.02% and 0.22% of the total CEC. Both of the FES show a very strong selectivity for Cs+ over Na+ (K(Na-Cs)=10(7.22) and 10(4.93), respectively). The third site, accounting for over 99% of the total CEC, is associated with planar sites on expansible clays and shows a smaller Na+-Cs+ selectivity coefficient of 10(1.99). Parameters derived from a fit of binary batch experiments alone tend to under predict Cs+ retardation in the column experiments. The transport experiments indicate 72-90% of the Cs+ sorbed in experiments targeting exchange on FES was desorbed over a 10- and 24-day period, respectively. At high Cs+ concentrations, where sorption is controlled primarily by exchange on planar sites, 95% of the Cs+ desorption was desorbed. Most of the difficulty in desorbing Cs+ from FES is a result of the extremely high selectivity of these sites for Cs+, although truly irreversible sorption as high as 23% was suggested in one experiment. The conclusion that Cs+ exchange is largely reversible in a thermodynamic sense is supported by the ability to match Cs+ desorption curves almost quantitatively with an equilibrium reactive transport simulation. The model for Cs+ retardation developed here qualitatively explains the behavior of Cs+ in the Hanford vadose zone underneath a variety of leaking tanks with differing salt concentrations. The high selectivity of FES for Cs+ implies that future desorption and migration is very unlikely to occur under natural recharge conditions.     

The data game: Measurement,uncertainty, and the challenge of quality

“Measurement, Uncertainty, and the Challenge of Quality,” by Carl Frankel, argues that corporations expect too much of science and measurement, in parallel with a culture that is similarly disposed. While science and measurement are essential to environmental progress, they are also limited in important and often overlooked ways. For instance, risk assessment provides only grossly approximate answers, and subjective quality—a central component of sustainable development—is rarely measured at all. New strategies for measuring the qualitative aspects of experience are urgently required.     

Changing corporate environmental philosophy: Project renewal gets companies started

Project RENEWAL is an innovative new environmental business project taking place in New Jersey. Project RENEWAL stands for Resource Efficiency Network to Eliminate Waste and Liability. The purpose of this project is to investigate and promote the linkages between ecology, technology, and business economics for the benefit of the economy and the environment. This is a collaborative effort, initially focused on equipment and inventory assets, between the business and environmental communities in order to explore new ways to increase business efficiency and profitability and also benefit the environment. Participants in the project include representatives from industry, consulting, local and state government, environmental agencies, trade groups and academia. This article will outline the background and initial framework of Project RENEWAL's initiatives. (The authors are open to comments, suggestions, criticism, and most importantly input from others who share their vision and are willing to cooperatively accelerate the change process).     

Potential use of oil shale for direct production of power in Jordan

Up until the present, Jordan has relied almost exclusively on imported petroleum for its primary energy requirements. Encouraged by emerging technologies and recent fossil fuel discoveries, Jordanians are seriously examining exploitation of their own indigenous energy resources to meet projected mid- and long-term power requirements. The most prominent of the known resources is oil shale. This report addresses the oil shale-for-power-production option in Jordan. Under consideration are 20 MW and 50 MW demonstration units and a 400 MW commercial-scale plant. The report focuses on three areas: (i) the engineering feasibility of using Jordan's oil shale in a circulating fluidized bed combustion (CFBC) boiler; (ii) environmental aspects of the proposed oil shale-for-power plants(s); and (iii) the economic feasibility of the proposed plant(s). The results could be useful for other low- to middle-income countries considering oil shale as an option for power production.     

Energy economy of salmon aquaculture in the Baltic sea

Resource utilization in Atlantic salmon aquaculture in the Baltic Sea was investigated by means of an energy analysis. A comparison was made between cage farming and sea ranching enterprises each with yearly yields of 40 t of Atlantic salmon. A variety of sea ranching options were evaluated, including (a) conventional ranching, (b) ranching employing a delayed release to the sea of young smolts, (c) harvesting salmon both by offshore fishing fleets and as they return to coastal areas, and (d) when offshore fishing is banned, harvesting salmon only as they return to coastal areas where released. Inputs both from natural ecosystems (i.e., fish consumed by ranched salmon while in the sea and raw materials used for producing dry food pellets) and from the economy (i.e., fossil fuels and energy embodied in economic goods and services) were quantified in tonnes for food energy and as direct plus indirect energy cost (embodied energy). The fixed solar energy (estimated as primary production) and the direct and indirect auxiliary energy requirements per unit of fish output were expressed in similar units. Similar quantities of living resources in tonnes per unit of salmon biomass output are required whether the salmon are feeding in the sea or are caged farmed. Cage farming is about 10 times more dependent on auxiliary energies than sea ranching. Sea ranching applying delayed release of smolts is 35–45% more efficient in the use of auxiliary energies than conventional sea ranching and cage farming. Restriction of offshore fishing would make sea ranching 3 to 6.5 times more efficient than cage farming. The fixed solar energy input to Atlantic salmon aquaculture is 4 to 63 times larger than the inputs of auxiliary energy. Thus, cage farming and sea ranching are both heavily dependent on the productivity of natural ecosystems. It is concluded that sustainable development of the aquaculture industry must be founded on ecologically integrated technologies which utilize the free production in marine ecosystems without exhausting or damaging the marine environment.     

Complex co‐substrate addition increases initial petroleum degradation rates during land treatment by altering bacterial community physiology

A pilot‐scale land treatment unit (LTU) was constructed at the former Guadalupe oil production field with the purpose of investigating the effect of co‐substrate addition on the bacterial community and the resulting rate and extent of total petroleum hydrocarbon (TPH) degradation. The TPH was a weathered mid‐cut distillate (C10‐C32) excavated from the subsurface and stockpiled before treatment. A control cell (Cell 1) in the LTU was amended with nitrogen and phosphorus while the experimental cell (Cell 2) was amended with additional complex co‐substrate—corn steep liquor. During the pilot LTU operation, measurements were taken of TPH, nutrients, moisture, aerobic heterotrophic bacteria (AHB), and diesel oxidizing bacteria (DOB). The bacterial community was also assayed using community‐level physiology profiles (CLPP) and 16S rDNA terminal restriction fragment (TRF) analysis. TPH degradation in both cells was characterized by a rapid phase of degradation that lasted for the first three weeks, followed by a slower degradation phase that continued through the remainder of the project. The initial rate of TPH‐degradation in Cell 1 (?0.021 day^?1) was slower than in Cell 2 (?0.035 day^?1). During the slower phase, degradation rates in both cells were similar (?0.0026 and ?0.0024 respectively). AHB and DOB counts were similar in both cells during the fast degradation phase. A second addition of co‐substrate to Cell 2 at the beginning of the slow degradation phase resulted in an increased AHB population that lasted for the remainder of the project but did not affect TPH degradation rates. CLPP data showed that co‐substrate addition altered the functional capacity of the bacterial community during both phases of the project. However, TRF data indicated that the phylogenetic composition of the community was not different in the two cells during the fast degradation phase. The bacterial phylogenetic structure in Cell 2 differed from Cell 1 after the second application of co‐substrate, during the slow degradation phase. Thus, co‐substrate addition appeared to enhance the functional capacity of the bacterial community during the fast degradation phase when the majority of TPH was bioavailable, resulting in increased degradation rates, but did not affect rates during the slow degradation phase when the remaining TPH may not have been bioavailable. These data show that co‐substrate addition might prove most useful for applications such as land farming where TPH is regularly applied to the same soil and initial degradation rates are more important to the project goals. © 2003 Wiley Periodicals, Inc.     

MODELING ACID MINE DRAINAGE ON A WATERSHED SCALE FOR TMDL CALCULATIONS1

ABSTRACT: The Cheat River of West Virginia is impaired by acid mine drainage (AMD). Fifty‐five of its river segments were placed on the 303(d) list, which required calculations of total maximum daily load (TMDL) to meet the water quality criteria for pH, total iron, aluminum, manganese, and zinc. An existing watershed model was enhanced to simulate AMD as nonpoint source load. The model divided a watershed into a network of catchments and river segments. Each catchment was divided into soil layers, which could contain pyrite, calcite and other minerals. A kinetic expression was used to simulate pyrite oxidation as a function of oxygen in the soil voids. Oxygen in the soil voids was consumed by pyrite oxidation and replenished by earth breathing. The by‐products of pyrite oxidation were calculated according to its mass action equations. Chemical equilibrium was used to account for the speciation of ferrous and ferric irons and precipitation of metal hydroxides. Simulated hydrology and water quality were compared to available data. The USEPA used the calibrated model to calculate the TMDLs in the Cheat River Watershed.