A quantum cascade laser infrared spectrometer for CO2 stable isotope analysis: Field implementation at a hydrocarbon contaminated site under bio-remediation

Real-time methods to monitor stable isotope ratios of CO_2 are needed to identify biogeochemical origins of CO_2 emissions from the soil–air interface. An isotope ratio infra-red spectrometer(IRIS) has been developed to measure CO_2 mixing ratio with δ~13C isotopic signature, in addition to mixing ratios of other greenhouse gases(CH_4, N2_O). The original aspects of the instrument as well as its precision and accuracy for the determination of the isotopic signature δ~13C of CO_2 are discussed. A first application to biodegradation of hydrocarbons is presented, tested on a hydrocarbon contaminated site under aerobic bio-treatment. CO_2 flux measurements using closed chamber method is combined with the determination of the isotopic signature δ~13C of the CO_2 emission to propose a non-intrusive method to monitor in situ biodegradation of hydrocarbons. In the contaminated area, high CO_2 emissions have been measured with an isotopic signature δ~13C suggesting that CO_2 comes from petroleum hydrocarbon biodegradation.This first field implementation shows that rapid and accurate measurement of isotopic signature of CO_2 emissions is particularly useful in assessing the contribution of contaminant degradation to the measured CO_2 efflux and is promising as a monitoring tool for aerobic bio-treatment.     

Regional specialization and market integration: agroecosystem energy transitions in Upper Austria

We investigate agroecosystem energy flows in two Upper Austrian regions, the lowland region Sankt Florian and the prealpine region Grünburg, at five time points between 1830 and 2000. Energetic agroecosystem productivity (energy contents of crops, livestock products, and wood per unit area) is compared to different types of energy inputs, i.e., external inputs from society (labor, industrial inputs, and external biomass inputs) and biomass reused from the local agroecosystem (feed, litter, and seeds). Energy transfers between different compartments of the agroecosystem (agricultural land, forest, and livestock) are also quantified. This allows for delineating an agroecosystem energy transition: In the first stage of this transition, i.e., in the nineteenth century, agroecosystem productivity was low (final produce ranged between 14 and 27 GJ/ha/yr), and local biomass reused made up 97% of total energy inputs in both regions (25–61 GJ/ha/yr). In this period, agroecosystem productivity increase was achieved primarily through more recycling of energy flows within the agroecosystems. In the second stage of the agroecosystem energy transition, i.e., after World War II, external energy inputs increased by factors 2.5 (Sankt Florian) and 5.0 (Grünburg), partly replacing local energy transfers. Final produce per area increased by factors 6.1 (Sankt Florian) and 2.9 (Grünburg). The difference in the resulting energy returns on investment (EROI) owes to regional specialization on cropping versus livestock rearing and to increasing market integration. Our results suggest that sustainable land-use intensification may benefit from some regional specialization harnessing local production potentials based on a mix of local and external inputs.

     

Orientation in the intertidal salt-marsh collembolan Anurida maritima

We investigated the cues used by the intertidal insect Anurida maritima (Apterygota: Collembola) to orient to the appropriate zone in which to seek shelter during high tide. Our experiments clearly ruled out any significant role for magnetic, local topographic, slope or celestial cues. Instead, we suggest that the difference between the appearance of the up-shore and the down-shore horizon is the major cue used by the collembolans. When a mirror was used to duplicate either of the two horizons, the insects were not able to orient. The insects moved towards an artificially dark horizon (the reverse of the mirror) placed down-shore, the opposite of their usual direction of movement. The insects had an endogenous circatidal rhythm of phototactic behaviour: most of the population was always negatively phototactic, but between 2 and 7 h after low tide, a significant proportion of the population became positively phototactic. This is the first demonstration of an endogenous tidal rhythm of orientation in an insect. Received: 31 May 1999 / Received in revised form: 1 February 2000 / Accepted: 19 February 2000     

A Field Demonstration of the UV/Oxidation Technology to Treat Ground Water Contaminated with VOCs

This paper presents the Geld evaluation results of the ultraviolet radiation (UV)/oxidation technology developed by Ultrox International, Santa Ana, California. The Geld evaluation was performed at the Lorentz Barrel and Drum (LB&D) site in San Jose, California, under the Superfund Innovative Technology Evaluation program in February and March of 1989.

The UV/oxidation technology uses UV radiation, ozone, and hydrogen peroxide to oxidize organic contaminants present in water. At the LB&D site, this technology was evaluated in treating ground water contaminated with volatile organic compounds (VOCs). The Ultrox system achieved VOC removals greater than 90 percent. Most VOCs were removed through chemical oxidation. However, for a few VOCs, such as 1, 1, 1-trichloroethane and 1, 1-dichloroethane, stripping also contributed toward removal. The treated ground water met the applicable discharge standards for discharge into a local waterway at 95 percent confidence level. There were no harmful air emissions to the atmosphere from the Ultrox system, which is equipped with an off-gas treatment unit.     

Macrofaunal recolonisation following the intertidal placement of fine-grained dredged material

Dredged material is increasingly being regarded as a potential resource, and one of its many uses is to create and/or improve intertidal habitats (i.e. beneficial use). However, uncertainties over the longer-term environmental consequences of such schemes have, to date, limited the practice to small-scale applications in UK waters. This paper studies the macrofaunal recolonisation of fine-grained dredged material recharged concurrently at four adjacent recharge areas along the south-east coast of the UK in order to facilitate predictions regarding the recolonisation of comparable schemes and, thereby, to promote effective environmental management. During the 2-year study period, the four recharge areas were distinctly different in terms of their environmental characteristics, primarily wave exposure and bed level. These conditions resulted in different macrofaunal recolonisation rates and community structures. While the low-level, wave-sheltered area experienced rapid recolonisation, the process was delayed until 12 months post-recharge at the relatively wave-exposed areas. Bed level differences resulted in distinctly different communities in wave-sheltered areas but not under wave-exposed conditions. While we are unable to separate the effects of individual environmental variables on recolonisation, these results provide general conclusions as to the importance of environmental conditions on resulting macrofaunal communities.     

A climatic driver for abrupt mid-Holocene vegetation dynamics and the hemlock decline in New England

The mid-Holocene decline of eastern hemlock is widely viewed as the sole prehistorical example of an insect- or pathogen-mediated collapse of a North American tree species and has been extensively studied for insights into pest-host dynamics and the consequences to terrestrial and aquatic ecosystems of dominant-species removal. We report paleoecological evidence implicating climate as a major driver of this episode. Data drawn from sites across a gradient in hemlock abundance from dominant to absent demonstrate: a synchronous, dramatic decline in a contrasting taxon (oak); changes in lake sediments and aquatic taxa indicating low water levels; and one or more intervals of intense drought at regional to continental scales. These results, which accord well with emerging climate reconstructions, challenge the interpretation of a biotically driven hemlock decline and highlight the potential for climate change to generate major, abrupt dynamics in forest ecosystems.     

Characterization of polycyclic aromatic hydrocarbons in urban stormwater runoff flowing into the tidal Anacostia River, Washington, DC, USA

To investigate the sources, fate, and transport dynamics of PAHs (polycyclic aromatic hydrocarbons) in stormwater runoff that is a leading source of pollution in urban watersheds, storm and base flow samples were collected in six branches along the lower Anacostia River. PAHs in storm flow (1510-12,500 ng/L) were significantly enriched in the particle phase, which accounted for 68-97% of the total PAHs. It suggests that reducing particles in stormwater using post-treatment system would decrease PAHs considerably. The solid-water distribution coefficients (KD) of PAHs in the storm flow samples were up to 340 times higher than predicted values. A greater portion of high molecular weight PAHs and their distribution patterns indicate higher contribution of automobile originated pyrogenic PAHs. Total suspended solids in storm flow had a positive relationship with flow rates and exceeded benchmark level for the protection of aquatic biota in some samples.     

Chemical Partitioning to Foliage: The Contribution and Legacy of Davide Calamari

- DOI: http://dx.doi.org/10.1065/espr2006.01.002 Background Davide Calamari and his colleagues were among the first to appreciate that vegetation could play a key role in determining the fate and effects of organic contaminants. They conducted pioneering experiments to investigate the uptake of contaminants by plants from the atmosphere and they sought to model the observed phenomena. In the nearly two decades since there has been a marked increase in understanding of these phenomena as a result of both experimental and modelling studies. - Goal. In this study we briefly review our current understanding of chemical partitioning between foliage and air. A model in both fugacity and concentration format is described, based on that of Tolls and McLachlan (1994), in which the leaf is treated as consisting of two layers, a waxy cuticle with an underlying 'reservoir' layer, the cuticle being surrounded by an air boundary layer and containing stomata that provide direct access from the air to the 'reservoir'. The model quantifies the dynamic penetration of a defined chemical into a defined leaf as a function of time. Main Features The model is applied for illustrative purposes to a hypothetical but typical leaf for a set of illustrative chemicals to demonstrate the effect of changes in physical-chemical properties and leaf characteristics. Discussion The results are compared qualitatively with a variety of field and laboratory studies of foliage uptake and clearance of chemicals. Conclusion It is concluded that the model yields results that are generally consistent with observations. It is suggested that with appropriate parameterisation and validation, the model can contribute to an improved understanding of the process of foliage uptake from the atmosphere and to the development of an improved predictive capability.     

FLOOD MANAGEMENT: WHO BENEFITS AND WHO PAYS1

ABSTRACT: The distribution of costs and benefits among groups in society of alternative flood management actions is examined in terms of their final incidence or resting place-their influence on real estate values. The alternatives examined include structures, disaster relief, floodproofing, watershed land treatment, floodplain zoning, and flood insurance. The impact of each alternative on the amount of flood disability cost paid by the landowner is examined and variations among alternatives are used to explain the past political success of structures and relief as compared to zoning, floodproofing, and insurance.