TBT and TPhT persistence in a sludged soil

The persistence of tributyltin (TBT) and triphenyltin (TPhT) in soils was studied, taking into consideration the quantity of sewage sludge, TBT and TPhT concentrations in soil as well as the soil pH. The organotin compounds (OTC) were introduced into the soil via a spiked urban sludge, simulating agricultural practise. OTC speciation was achieved after acidic extraction of soil samples followed by gas chromatography–pulsed flame photometric analysis (GC–PFPD). Leaching tests conducted on a spiked sludge showed that more than 98% of TBT are sorbed on the sludge. TBT persistence in soil appeared to depend on its initial concentration in sludge. Thus, it was more important when concentration is over 1000 μg(Sn) kg⁻¹ of sludge. More than 50% of the initial TBT added into the soil were still present after 2 months, whatever the experimental conditions. The main degradation product appeared to be dibutyltin. About 90% of TPhT were initially sorbed on sludge, whatever the spiking concentration in sludge was. However, TPhT seemed to be quantitatively exchangeable at the solid/liquid interface, according to the leaching tests. It was also significantly degraded in sludged soil as only about 20% of TPhT remain present after 2 months, the monophenyltin being the main degradation product. pH had a significant positive effect on TBT and particularly TPhT persistence, according to the initial amounts introduced into the soil. Thus, at pH over 7 and triorganotin concentration over 100 μg(Sn) kg⁻¹, less than 10% of TBT but about 60% of TPhT were degraded. When the sludge was moderately contaminated by triorganotins (typically 50 μg(Sn) kg⁻¹ in our conditions) the pH had no effect on TBT and TPhT persistence.     

Stricter Ozone Ambient Air Quality Standard Has Beneficial Effect on Ponderosa Pine in California

Ambient air quality standards and control strategies are implemented to protect humans and vegetation from adverse effects. We used a process-based tree-growth model (TREGRO) to show that over the past 37 years, changes in O₃ exposure, with accompanying variation in climate, are reflected in changes in the growth of Pinus ponderosa Dougl. ex Laws. in the San Bernardino Mountains near Los Angeles, California, USA. Despite variation in temperature and precipitation over the study period (1963–1999), O₃ exposure consistently reduced simulated tree growth. Simulated growth reductions increased concurrent with increasing O₃ exposure. The maximum growth reduction occurred in 1979. As O₃ exposures decreased during the 1980s and 1990s, effects on growth also decreased. This implies that emission control strategies taken to reduce exposures to attain O₃ standards benefited P. ponderosa growth in the San Bernardino Mountains. This modeling approach provides a powerful tool for solving the difficult problem of evaluating regulatory effectiveness by simulating plant response using long-term climate and air pollution exposure records for a given region.Phone 541 754-4621 Fax 541 754-4799     

A Method for Improving the Management of Controversial Wetland

Valley bottom wetlands in agricultural landscapes often are neglected in national and regional wetland inventories. Although these areas are small, located in the bottomlands of the headwater catchments, and scattered in the rural landscape, they strongly influence hydrology, water quality, and biodiversity over the whole catchment area. Valley bottom wetlands often are considered as controversial wetlands. Awareness of the functional role of wetlands is increasing, in parallel with their progressive disappearance in intensive farming landscapes. The need to improve tools for controlling wetland management is a primary consideration for decision makers and land users. This article proposes a method for the inventory of valley bottom wetlands. The method is based on the functional analysis of potential, existing, and efficient valley bottom wetlands (the PEEW approach). Several indicators are proposed for checking the validity of such an approach. Potential wetlands are delineated by means of a topographic index using topographic and pedoclimatic criteria computed from a Digital Elevation Model and easily accessible databases. Existing wetlands are identified from observed surface moisture, the presence of specific wetland vegetation, or soil feature criteria. Efficient wetlands are defined through a given function, such as flow or pollutant regulation or biodiversity control. An analysis of areas at the limits between potential, existing, and efficient wetlands highlights land cultivated or drained in the past, which currently represents negotiating areas in which rehabilitation and other intended management actions can be implemented.     

Agricultural practices in grasslands detected by spatial remote sensing

The major decrease in grassland surfaces associated with changes in their management that has been observed in many regions of the earth during the last half century has major impacts on environmental and socio-economic systems. This study focuses on the identification of grassland management practices in an intensive agricultural watershed located in Brittany, France, by analyzing the intra-annual dynamics of the surface condition of vegetation using remotely sensed and field data. We studied the relationship between one vegetation index (NDVI) and two biophysical variables (LAI and fCOVER) derived from a series of three SPOT images on one hand and measurements collected during field campaigns achieved on 120 grasslands on the other. The results show that the LAI appears as the best predictor for monitoring grassland mowing and grazing. Indeed, because of its ability to characterize vegetation status, LAI estimated from remote sensing data is a relevant variable to identify these practices. LAI values derived from the SPOT images were then classified based on the K-Nearest Neighbor (KNN) supervised algorithm. The results points out that the distribution of grassland management practices such as grazing and mowing can be mapped very accurately (Kappa index?=?0.82) at a field scale over large agricultural areas using a series of satellite images.     

Spatial mapping of city-wide PBDE levels using an exponential decay model

Passive air samplers (PAS) consisting of polyurethane foam (PUF) disks were deployed at 6 outdoor air monitoring stations in different land use categories (commercial, industrial, residential and semi-rural) to assess the spatial distribution of polybrominated diphenyl ethers (PBDEs) in the Brisbane airshed. Air monitoring sites covered an area of ~1143 km(2) and PAS were allowed to accumulate PBDEs in the city's airshed over three consecutive seasons commencing in the winter of 2008. The average sum of five (∑(5)) PBDEs (BDEs 28, 47, 99, 100 and 209) levels were highest at the commercial and industrial sites (12.7 ± 5.2 ng PUF(-1)), which were relatively close to the city center and were a factor of 8 times higher than residential and semi-rural sites located in outer Brisbane. To estimate the magnitude of the urban 'plume' an empirical exponential decay model was used to fit PAS data vs. distance from the CBD, with the best correlation observed when the particulate bound BDE-209 was not included (∑(5)-209) (r(2) = 0.99), rather than ∑(5) (r(2) = 0.84). At 95% confidence intervals the model predicts that regardless of site characterization, ∑(5)-209 concentrations in a PAS sample taken between 4-10 km from the city centre would be half that from a sample taken from the city centre and reach a baseline or plateau (0.6 to 1.3 ng PUF(-1)), approximately 30 km from the CBD. The observed exponential decay in ∑(5)-209 levels over distance corresponded with Brisbane's decreasing population density (persons/km(2)) from the city center. The residual error associated with the model increased significantly when including BDE-209 levels, primarily due to the highest level (11.4 ± 1.8 ng PUF(-1)) being consistently detected at the industrial site, indicating a potential primary source at this site. Active air samples collected alongside the PAS at the industrial air monitoring site (B) indicated BDE-209 dominated congener composition and was entirely associated with the particulate phase. This study demonstrates that PAS are effective tools for monitoring citywide regional differences however, interpretation of spatial trends for POPs which are predominantly associated with the particulate phase such as BDE-209, may be restricted to identifying 'hotspots' rather than broad spatial trends.     

Determination of 14 amines in air samples using midget impingers sampling followed by analysis with ion chromatography in tandem with mass spectrometry

An Ion Chromatography-Mass Spectrometry (IC-MS) method was developed for the simultaneous quantification of 14 volatile amines in air. The method includes collection of compounds into two midget impingers in a row filled with 15 ml of ultrapure water. The analytical performances with mass spectrometry detection were compared to those obtained with classical conductivity detection. The use of mass spectrometry detection (in SIM mode) overcomes most of the coelutions encountered with conductivity detection. Although the linearity domain of calibrations is reduced for the MS detection as compared with the CD detection, the detection limits in MS detection are highly lowered allowing the quantification of amines at the levels of μg m(-3) in air with a good accuracy for most compounds (RSD of less than 10%). This method was successfully applied to the analysis of amines released from polyurethane foams. Seven amines were identified and some in high concentrations, like dimethylaminoethanol, NIAX and TEDA.     

Structure and fate of a Pseudomonas aeruginosa population originating from a combined sewer and colonizing a wastewater treatment lagoon

The efficacy of a wastewater treatment lagoon (WWTL) at preventing the spread of Pseudomonas aeruginosa into natural aquatic habitats was investigated. A WWTL and its connected combined sewer and brook were exhaustively sampled. Physico-chemical analyses showed a stratification of the first pond according to pH, temperature and oxygen content. The P. aeruginosa counts partially matched this stratification with higher values among the bottom anaerobic waters of the first half of this pond. Genotyping of 494 WWTL P. aeruginosa strains was performed and led to the definition of 85 lineages. Dominant lineages were observed, with some being found all over the WWTL including the connected brook. IS5 was used as an indicator of genomic changes, and 1 to 12 elements were detected among 16 % of the strains. IS-driven lasR (genetic regulator) disruptions were detected among nine strains that were not part of the dominant lineages. These insertional mutants did not show significant elastase activities but showed better growth than the PAO1 reference strain in WWTL waters. Differences in growth patterns were related to a better survival of these mutants at an alkaline pH and a better ability at using some C-sources such as alanine. The opportunistic colonization of a WWTL by P. aeruginosa can involve several metabolic strategies which appeared lineage specific. Some clones appeared more successful than others at disseminating from a combined sewer toward the overflow of a WWTL.     

Pilot scale application of a method for the analysis of perfluorinated compounds in surface soils

A growing number of studies now indicate that perfluorinated compounds (PFCs) are globally distributed in the environment. Their widespread distribution and presence in remote locations has led to questions about the importance of atmospheric and oceanic transport. Describing their distribution in surface soils is also an essential but neglected element in developing a comprehensive understanding of their occurrence in the environment. Soils are the critical link between global atmospheric and hydrologic processes where both local and distant contaminants can accumulate and be released into aquatic and terrestrial communities. Because PFC concentrations in soils will influence ground and surface water, wildlife, and crops, methods to accurately measure PFCs in soil are clearly needed. To help answer this need, we developed a method for the analysis of nine perfluorinated carboxylic acids and four perfluorinated sulfonic acids in soil. Samples from six nations (n = 10 per nation) were analyzed by LC-MS/MS to demonstrate the method performance parameters and to make preliminary observations about the occurrence of the PFCs in soils in different parts of the world. The resulting method shows acceptable performance characteristics for the target compounds in most soils while documenting the widespread occurrence of PFCs in surface soils.