Bioremediation of TCE in a fractured limestone aquifer using a novel horizontal passive biobarrier

This article discusses a project demonstrating the successful use of a novel horizontal biobarrier approach to protect a fractured limestone aquifer from continuing contamination while passive bioremediation of the overlying clay till source area is in progress. The emplacement of the biobarrier has significantly reduced the concentrations of chlorinated ethenes and dechlorination activity in the limestone aquifer, promoting complete reductive dechlorination of the trichloroethene plume. The biobarrier strategy has thus met the challenge of protecting the limestone from the overlying overburden. Direct GeoProbe injections performed in the source area, which consist of a clay till overburden, have also reduced the contaminant concentrations in the clay till due to enhanced dechlorination activity; however, repeat injections may be required to address the areas of the till in which the injectate has not yet been distributed. The time frame for remediating the source area in the till is expected to be on the order of a decade. © 2010 Wiley Periodicals, Inc.     

Xanthoria parietina as a monitor of ground-level ambient ammonia concentrations

Total nitrogen in transplanted and in situ lichen thalli of Xanthoria parietina were related to ambient ammonia air concentrations measured with passive ALPHA (Adapted Low-cost Passive High Absorption) diffusion samplers in Denmark. Transplants and ALPHA samplers were exposed four months in a transect on heathland close to a pig farm. Monthly mean ammonia concentrations declined exponentially approaching background levels after 300 m. Nitrogen content of the lichen transplants tended to decline with distance, though only a few stations were significantly different from each other. Where ammonia concentrations were high, maximum content of nitrogen was reached after one month of exposure. Conversely, at sites with background concentrations, it took several months to reach a statistically significant uptake. The correlation between ammonia concentration in the air and in situ X. parietina was significant.     

Hydrogeological relationships of sandy deposits: modeling of two-dimensional unsaturated water and pesticide transport

Prediction of the movement of water and solutes in the vadose zone requires information on the distribution of spatial trends and heterogeneities in porous media. The present study describes different lithofacies origination mainly from glaciofluvial deposits. Among different lithofacies, hydrological relationships were investigated. By means of a two-dimensional hydrological model it was evaluated how the flow of water and leaching of metribuzin (4-amino-6-tert-butyl-4,5-dihydro-3-methylthio-1,2,4-triazin-5-one) was affected. Two selected large outcrop sections consisting of glacial outwash deposits were used in the modeling study. Eleven different lithofacies were distinguished and described in terms of texture distribution, sorting, bedding style, and external boundaries based on excavated soil profiles from 27 locations representing seven predominantly sandy landforms in Denmark. Undisturbed soil columns were sampled from each of the lithofacies and brought to the laboratory to be analyzed. With respect to their soil hydraulic properties, the different lithofacies formed four different hydrofacies having relatively homogeneous, hydrogeological properties. Two large outcrop sections from one of the locations (a gravel pit) located near the terminal moraine of the former Weichsel glacier were used for the HYDRUS-2D modeling. Modeling results revealed that the spatial distribution of sedimentary bodies affected water flow and the leaching of metribuzin.     

Estimates of black carbon and size-resolved particle number emission factors from residential wood burning based on ambient monitoring and model simulations

In this paper we derive typical emission factors for coarse particulate matter (PM(10)), oxides of nitrogen (NO(x)), black carbon (BC), and number particle size distributions based on a combination of measurements and air quality dispersion modeling. The advantage of this approach is that the emission factors represent integrated emissions from several vehicle types and different types of wood stoves. Normally it is very difficult to estimate the total emissions in cities on the basis of laboratory measurements on single vehicles or stoves because of the large variability in conditions. The measurements were made in Temuco, Chile, between April 18 and June 15, 2005 at two sites. The first one was located in a residential area relatively far from major roads. The second site was located in a busy street in downtown Temuco where wood consumption is low. The measurements support the assumption that the monitoring sites represent the impact of different emission sources, namely traffic and residential wood combustion (RWC). Fitting model results to the available measurements, emission factors were obtained for PM(10) (RWC = 2160 +/- 100 mg/kg; traffic = 610 +/- 51 mg/veh-km), NO(x) (RWC = 800 +/- 100 mg/kg; traffic = 4400 +/- 100 mg/veh-km), BC (RWC = 74 +/- 6 mg/kg; traffic = 60 +/- 3 mg/veh-km) and particle number (N) with size distribution between 25 and 600 nm (N(25-600)) (RWC = 8.9 +/- 1 x 10(14) pt/kg; traffic = 6.7 +/- 0.5 x 10(14) pt/veh-km). The obtained emission factors are comparable to results reported in the literature. The size distribution of the N emission factors for traffic was shown to be different than for RWC. The main difference is that although traffic emissions show a bimodal size distribution with a main mode below 30 nm and a secondary one around 100 nm, RWC emissions show the main mode slightly below 100 nm and a smaller nucleation mode below 50 nm.     

Geochemical anomalies from bottom ash in a road construction--comparison of the leaching potential between an ash road and the surroundings

A study was performed between June 2001 and December 2004 with the primary objective of assessing long-term leaching from municipal solid waste incineration bottom ash in a test road construction in relation to a reference road made up of conventional materials and the natural geochemical conditions in the surroundings. The metal leaching from the test road and the reference road was compared with the natural weathering in the regional surroundings for three time scales: 16, 80 and 1000 years. The results show that Cu and Zn cause a geochemical anomaly from the test road compared with the surroundings. The leaching of Cu from the test road is initially high but will decline with time and will in the long term be exceeded by natural weathering. Zn on the other hand has low initial leaching, which will increase with time and will in the long term exceed that of the test road and the surroundings by a factor of 100-300. For the other metals studied, Al, Na, K and Mg, there is only very limited leaching over time and the potential accumulation will not exceed the background values in a 1000 years.     

Transaction Costs Economics of Irreplaceability: <Emphasis Type="Italic">ex ante</Emphasis> and <Emphasis Type="Italic">ex post</Emphasis> Evaluation of Conservation Networks’ Vulnerability to Environmental Shocks

The theoretical concept, “asset specificity,” is applied to real data in the context of Danish nature conservation network planning in order to produce illustrative examples of an economic measure of the network’s vulnerability to exogenous shocks to the species composition. Three different measures of asset specificity are quantified from the shadow value of eliminating a key species from the individual grid cells. This represents a novel approach and a different interpretation of the term, as it is conventionally used as a qualitative indicator in the transaction cost economics literature. Apart from supplementing existing cost measures with an indicator of risk associated with investments in protected areas, this study demonstrates how the estimation and interpretation of various asset specificity measures for geographical areas may qualify policy makers’ choice of policy instrument in conservation planning. This differs from the more intuitive approach of basing policy instrument choice solely on the rarity of the species in a given area.     

Irrigation of treated wastewater in Braunschweig, Germany: an option to remove pharmaceuticals and musk fragrances

In this study the fate of pharmaceuticals and personal care products which are irrigated on arable land with treated municipal wastewater was investigated. In Braunschweig, Germany, wastewater has been irrigated continuously for more than 45 years. In the winter time only the effluent of the sewage treatment plant (STP) of Braunschweig is used for irrigation, while during summer digested sludge is mixed with the effluent. In the present case study six wells and four lysimeters located in one of the irrigated agricultural fields were monitored with regard to the occurrence of 52 pharmaceuticals and two personal care products (PPCPs; e.g. betablockers, antibiotics, antiphlogistics, carbamazepine, musk fragrances, iodinated contrast media (ICM) and estrogens). No differences in PPCP pollution of the groundwater were found due to irrigation of STP effluents with and without addition of digested sludge, because many polar compounds do not sorb to sludge and lipophilic compounds are not mobile in the soil-aquifer. Most of the selected PPCPs were never detected in any of the lysimeter or groundwater samples, although they were present in the treated wastewater irrigated onto the fields. In the groundwater and lysimeter samples primarily the ICM diatrizoate and iopamidol, the antiepileptic carbamazepine and the antibiotic sulfamethoxazole were detected up to several mugl(-1), while the acidic pharmaceuticals, musk fragrances, estrogens and betablockers were likely sorbed or transformed while passing the top soil layer. Potential estrogenic effects are likely to disappear after irrigation, since the most potent steroid estrogens were not measurable.     

Conceptual development of a harmonised method for tracking change and evaluating policy in the agri-environment: The Agri-environmental Footprint Index

An aggregated farm-level index, the Agri-environmental Footprint Index (AFI), based on multiple criteria methods and representing a harmonised approach to evaluation of EU agri-environmental schemes is described. The Index uses a common framework for the design and evaluation of policy that can be customised to locally relevant agri-environmental issues and circumstances. Evaluation can be strictly policy-focused, or broader and more holistic in that context-relevant assessment criteria that are not necessarily considered in the evaluated policy can nevertheless be incorporated. The Index structure is flexible, and can respond to diverse local needs. The process of Index construction is interactive, engaging farmers and other relevant stakeholders in a transparent decision-making process that can ensure acceptance of the outcome, help to forge an improved understanding of local agri-environmental priorities and potentially increase awareness of the critical role of farmers in environmental management. The structure of the AFI facilitates post-evaluation analysis of relative performance in different dimensions of the agri-environment, permitting identification of current strengths and weaknesses, and enabling future improvement in policy design. Quantification of the environmental impact of agriculture beyond the stated aims of policy using an ‘unweighted’ form of the AFI has potential as the basis of an ongoing system of environmental audit within a specified agricultural context.     

Incentives and outcomes: Evaluation of a Swedish environmental subsidy programme

This paper empirically evaluates a Swedish government subsidy to environmental sustainability, the Local Investment Programme (LIP). During the programme period, 1998 – 2002, more than 670 million was granted to 1814 different municipal projects, making it the largest Swedish subsidization to ecological sustainability to date. For the 682 projects evaluated here, it was found that the projects were rewarded smaller subsidies than granted. To explain the gap between granted and rewarded subsidies, the gap was decomposed into a quantity effect, depending on the quantified environmental and employment outcomes of the projects, and a price effect, depending on the government's valuation of these outcomes. Whereas no statistically significant quantity effect was found, there was a large statistically significant price effect, indicating that the government paid the municipalities less than promised in the granting decision.     

Mitigation of methane emission from an old unlined landfill in Klintholm,Denmark using a passive biocover system

Methane generated at landfills contributes to global warming and can be mitigated by biocover systems relying on microbial methane oxidation. As part of a closure plan for an old unlined landfill without any gas management measures, an innovative biocover system was established. The system was designed based on a conceptual model of the gas emission patterns established through an initial baseline study. The study included construction of gas collection trenches along the slopes of the landfill where the majority of the methane emissions occurred. Local compost materials were tested as to their usefulness as bioactive methane oxidizing material and a suitable compost mixture was selected. Whole site methane emission quantifications based on combined tracer release and downwind measurements in combination with several local experimental activities (gas composition within biocover layers, flux chamber based emission measurements and logging of compost temperatures) proved that the biocover system had an average mitigation efficiency of approximately 80%. The study showed that the system also had a high efficiency during winter periods with temperatures below freezing. An economic analysis indicated that the mitigation costs of the biocover system were competitive to other existing greenhouse gas mitigation options.