Processes affecting the movement of organochlorine pesticides (OCPs) between soil and air in an industrial site in Turkey

Soil and atmospheric concentrations, dry deposition and soil-air gas exchange of organochlorine pesticides (OCPs) were investigated at an industrial site in Aliaga, Izmir, Turkey. Current-use pesticides, endosulfan and chlorpyrifos, had the highest atmospheric levels in summer and winter. Summertime total (gas + particle) OCP concentrations in air were higher, probably due to increased volatilization at higher temperatures and seasonal local/regional applications of current-use pesticides. Particle deposition fluxes were generally higher in summer than in winter. Overall average dry particle deposition velocity for all the OCPs was 4.9 ± 4.1 cm s⁻¹ (average ± SD). ΣDDXs (sum of p,p′-DDT, p,p′-DDD, and p,p′-DDE) were the most abundant OCPs in Aliaga soils (n = 48), probably due to their heavy historical use and persistence. Calculated fugacity ratios and average net gas fluxes across the soil-air interface indicated volatilization for α-CHL, γ-CHL, heptachlorepoxide, cis-nonachlor, trans-nonachlor, and p,p′-DDT in summer, and for α-CHL, γ-CHL, trans-nonachlor, endosulfan sulfate, and p,p′-DDT in winter. For the remaining OCPs, soil acted as a sink during both seasons. Comparison of the determined fluxes showed that dry particle, gas-phase, and wet deposition are significant OCP input mechanisms to the soil in the study area.     

Use and knowledge of fuelwood in three rural caatinga (dryland) communities in NE Brazil

The woody species known, used, and preferred as fuelwood were examined in three rural communities within the county of Soledade, Paraíba State, NE Brazil. Ethnobotanical information was collected using semi-structured interviews with more than 90% of the local households (55 adult residents; 31 women, and 24 males). The interviewees cited 36 plant species as fuelwoods, distributed among 30 genera and 15 families, in addition to two unidentified plants. The plant families represented by the largest numbers of species were Euphorbiaceae, Anacardiaceae, Mimosaceae, Caesalpiniaceae, Sapotaceae, and Fabaceae. The species Caesalpinia pyramidalis Tul. (“catingueira”) was cited with the greatest frequency in all three communities. Within the communities we found significant differences on the number of plants cited and actually used (p < 0.05), indicating that the residents knew more fuelwood species than they effectively harvest. The different distances from the communities to the urban centers were not related to differences on the use or the size of the stocks of fuelwood. Additionally, the study revealed that the communities examined still maintain a significant knowledge of the use of energy-providing plants in spite of the widespread use of liquefied petroleum gas (LPG). Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Low cost measurements of nitrogen and sulphur dry deposition velocities at a semi-alpine site: gradient measurements and a comparison with deposition model estimates

The conditional time averaged gradient method was used to measure air-surface exchange of nitrogen and sulphur compounds at a semi-alpine site in Southern Norway. Dry deposition velocities were then obtained from the bi-weekly concentration gradient measurements. Annual deposition velocities were found to be 1.4, 11.8 and 4.0 mm s(-1) for NH3, HNO3 and SO2, respectively, if all data were included, and to be 10.8, 11.8 and 13.0 mm s(-1), respectively, if only positive values were included. Measured deposition velocities were compared to two sets of values estimated from a big-leaf dry deposition module applying to two different land types (short grass and forbs, and tundra), driven by measured micrometeorological parameters. The deposition module gives reasonable values for this site throughout the year, but does not reproduce the large variability as shown in the measured data. No apparent seasonal variations were found from either measurements or module estimates due to the very low productivity of the studied area.     

Nitrogen deposition effects on Mediterranean-type ecosystems: an ecological assessment

We review the ecological consequences of N deposition on the five Mediterranean regions of the world. Seasonality of precipitation and fires regulate the N cycle in these water-limited ecosystems, where dry N deposition dominates. Nitrogen accumulation in soils and on plant surfaces results in peaks of availability with the first winter rains. Decoupling between N flushes and plant demand promotes losses via leaching and gas emissions. Differences in P availability may control the response to N inputs and susceptibility to exotic plant invasion. Invasive grasses accumulate as fuel during the dry season, altering fire regimes. California and the Mediterranean Basin are the most threatened by N deposition; however, there is limited evidence for N deposition impacts outside of California. Consequently, more research is needed to determine critical loads for each region and vegetation type based on the most sensitive elements, such as changes in lichen species composition and N cycling.     

Treatment-oriented characterization of dry scrubber residue from municipal solid waste incineration

 Dry scrubber residue from municipal solid waste incineration (MSWI) was characterized to identify critical inorganic pollutants and to suggest a conceptual treatment method. The key methods used were thermal analysis, including thermogravimetry (TG) and differential thermal analysis (DTA), pH_stat titration, qualitative X-ray diffraction (XRD), scanning electron microscopy (SEM), chemical equilibrium calculations, and statistics such as error propagation, principal component analysis (PCA), and empirical modeling based on factorial designs. Based on EU directives, the major inorganic pollutants Cd, Cr, Pb, and Zn were found. In addition, the pH was too high. With dry scrubber residue stabilization in mind, the impact of carbonation and hydration was assessed and judged to be encouraging. In particular, chemical equilibrium calculations showed that carbonation has considerable potential to lower the pH and the availability of Pb, Zn, and Cr. The impact of carbonation on the mobility of Cd was found to be small. During carbonation, a metal-trapping calcium aluminosilicate hydrate (C–A–S–H) phase is also formed. Both processes together have the potential to lead to a robust, reliable, and reasonable stabilization method for dry scrubber residue. However, to control these processes, the decisive factors need to be identified and their effects need to be quantified. Ca, Cl, Na, and K might be abundant components which would be mobile even after stabilization. Received: September 11, 2001 / Accepted: December 6, 2001     

防旱抗旱能力综合评价方法：—以关中地区为例

本文采用11项指标并确定相应的评分标准和权重分配,对关中地区进行防旱抗旱能力的综合评价,得出关中地区属中等抗旱能力区。由于经济发展需水超过供水能力,现状及本世纪末缺水率将超过20％。因而跨流域引水是今后长期供水的途径。     

Description and evaluation of a model of deposition velocities for routine estimates of dry deposition over North America. Part II: review of past measurements and model results

Numerical sensitivity tests and four months of complete model runs have been conducted for the Routine Deposition Model (RDM). The influence of individual model inputs on dry deposition velocity as a function of land-use category (LUC) and pollutant (SO₂, O₃, SO²⁻₄ and HNO₃) were examined over a realistic range of values for solar radiation, stability and wind speed. Spatial and temporal variations in RDM deposition velocity (V_d) during June – September 1996 time period generated using meteorological input from a mesoscale model run at 35 km resolution over north-eastern North America were also examined. Comparison of RDM V_d values to a variety of measurements of dry deposition velocities of SO₂, O₃, SO²⁻₄ and NHO₃ that have been reported in the literature demonstrated that RDM produces realistic results. Over northeastern NA RDM monthly averaged dry deposition velocities for SO₂ vary from 0.2 to 3.0 cm s⁻¹ with the highest deposition velocities over water surfaces. For O₃, the monthly averaged dry deposition velocities are from 0.05 to 1.0 cm s⁻¹ with the lowest values over water surfaces and the highest over forested areas. For HNO₃, the monthly averaged dry deposition velocities have the range of 0.5 to 6 cm s⁻¹, with the highest values for forested areas. For SO²⁻₄, they range from 0.05–1.5 cm s⁻¹, with the lowest values over water and the highest over forest. The monthly averaged dry deposition velocities for SO₂ and O₃ are higher in the growing season compared to the fall, but this behaviour is not apparent for HNO₃ and sulphate. In the daytime, the hourly averaged dry deposition velocities for SO₂, O₃, SO²⁻₄ and HNO₃ are higher than that in the nighttime over most of the vegetated area. The diurnal variation is most evident for surfaces with large values for leaf area index (LAI), such as forests. Based on the results presented in this paper, it is concluded that RDM V_d values can be combined with measured air concentrations over hourly, daily or weekly periods to determine dry deposition amounts and with wet deposition measurements to provide seasonal estimates of total deposition and estimates of the relative importance of dry deposition.     

A feasibility and cost comparison of perchloroethylene dry cleaning to professional wet cleaning: case study of Silver Hanger Cleaners, Bellingham, Massachusetts

The Toxics Use Reduction Institute (TURI) has been working with the dry cleaning sector for over 10 years - focusing on the ultimate goal of eliminating the use of perchloroethylene in this sector due to the availability of less toxic, feasible alternatives. Professional wet cleaning has been identified as one of these alternatives and has been a focus of the Institute in recent years. In 2008, the Institute provided a matching grant to Silver Hanger Cleaners in Bellingham, Massachusetts to convert their operations from perchloroethylene-based to water-based processes. Two years of data have been collected from the facility, reflecting one year of solvent use and one year of dedicated professional wet cleaning. The analysis of that data is presented here, including capital costs, performance data and associated costs, operational costs, and resource use and associated costs.     

Effect of land management on soil microbial N supply to crop N uptake in a dry tropical cropland in Tanzania

In Sub-Saharan Africa, conservation of available soil N during early crop growth, when N loss by leaching generally occurs, is important to improve crop productivity. In a dry tropical cropland in Tanzania, we assessed the potential role of soil microbes as a temporal N sink-source to conserve the available soil N until later crop growth, which generally requires substantial crop N uptake. We evaluated the effect of land management [i.e., no input, plant residue application before planting (P plot) with or without fertilizer application, fertilizer application alone, and non-cultivated plots] on the relationship between soil N pool [microbial biomass N (MBN) and inorganic N] and crop N uptake throughout the ∼120-d crop growth period in two consecutive years. In the P plot, MBN clearly increased (∼14.6-29.6 kg N ha⁻¹) early in the crop growth period in both years because of immobilization of potentially leachable N, and it conserved a larger soil N pool (∼10.5-21.2 kg N ha⁻¹) than in the control plot. Especially in one year in which N leaching was critical, increased MBN maintained a larger soil N pool in the P plot throughout the experimental period, and a delay of increased MB C:N ratio and a substantial decrease in MBN was observed, indicating better soil microbial N supply for crop N uptake during later crop growth. Therefore, plant residue application before planting should enhance the role of soil microbes as a temporal N sink-source, leading to the conservation of potentially leachable N until later phase of crop growth, especially in years in which N leaching is relatively severe. Although further studies are necessary, our results suggest that plant residue application before planting is a promising option to achieve better N synchronization.     

Application of micrometeorological approaches to measure methane exchange in a dry paddy field in the western coast of Korea

The exchange processes of CH₄ were investigated in a paddy field in the Hari area of Kang Hwa Island over an 8 day period in late April 2002. The quantification of CH₄ fluxes was made under dry field condition of early spring by concurrently measuring its concentrations (at the two heights of 1 and 5 m) and the relevant micrometeorological parameters. To help elucidate the factors determining the mobilization characteristics of CH₄, the results of our measurement data were examined using a number of approaches. The results of the trajectory analysis indicated that its concentration changed very sensitively with the influence of different source types, as seen from the air mass movement patterns. The concentrations and fluxes of methane, when examined over this short-term scale, showed moderately strong patterns across 24 h period in which higher values tend to occur during morning or evening. The overall results of our field measurements suggest that CH₄ exchange processes in the paddy area proceeded in a fairly complicated manner. The study area behaved as a net source of CH₄ to the atmosphere with a net daily emission rate of 3.6 mg m⁻² despite the fact that downward deposition was observed more frequently than upward emission.