Pesticides and metabolites in cassava, eucalyptus, plum and cashew leaves and roots in relation to a point source in Kibaha, Tanzania

Leaves of Eucalyptus sp., Prunus domestica (plum), and Anacardium occidentale (cashew), as well as roots and leaves of Manihot esculenta (cassava) were used to study the local distribution of pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. Eleven organochlorine pesticide residues namely pentachloroanisole, p,p'-DDT, o,p'-DDT, p,p'-DDE, o,p'-DDE, p,p'-DDD, o,p'-DDD, alpha-HCH, beta-HCH, delta-HCH and epsilon-HCH were detected in the samples. The concentrations of total DDT were 818 ng/g fw in Eucalyptus sp., 16 ng/g fw in A. occidentale and 4 ng/g fw in P. domestica. In M. esculenta, total DDT ranged from 191 to 586 ng/g fw in roots and 7 to 425 ng/g fw in leaves. The concentrations of total HCH were up to 15 ng/g fw in Eucalyptus sp., while the concentrations of pentachloroanisole were up to 2 ng/g fw in leaves of M. esculenta. There are very strong positive correlations in the concentrations of the detected compounds, suggesting that they have a common source. The low DDE/DDT ratios (0.02-0.07) in all samples indicate input of non-degraded DDT from the source. The high alpha-HCH/gamma-HCH ratios in some samples (>3.1-10) indicate input of technical HCH. The concentrations of total DDT in cassava roots were either very close to, or greater than, the FAO/WHO limit, indicating risks and concern to public health.     

Elemental analysis of ash residue from combustion of CCA treated wood waste before and after electrodialytic extraction

Element distribution in a combined fly ash and bottom ash from combustion of copper chromate arsenate (CCA) treated wood waste was investigated by scanning electron microscopy (SEM/EDX) before and after electrodialytic extraction. The untreated ash contained various particles, including pieces of incompletely combusted wood rich in Cr and Ca, and irregular particles rich in Si, Al and K. Cr was also found incorporated in silica-based matrix particles. As was associated with Ca in porous (char) particles, indicating that Ca-arsenates had been formed during combustion. Cu was associated with Cr in the incompletely combusted wood pieces and was also found in almost pure form in a surface layer of some matrix particles - indicating surface condensation of volatile Cu species. In treated ash, Ca and As were no longer found together, indicating that Ca-arsenates had been dissolved due to the electrodialytic treatment. Instead particles rich in Ca and S were now found, indicating precipitation of Ca-sulphates due to addition of sulphuric acid in connection with the electrodialytic treatment. Cu and Cr were still found associated with incompletely combusted wood particles and incorporated in matrix particles. Chemical analyses of untreated and treated ash confirmed that most As, but only smaller amounts of Cu and Cr was removed due to the electrodialytic extraction. Overall metal contents in the original ash residue were: 1.4 g As, 2.76 g Cu and 2.48 g Cr, after electrodialytic extraction these amounts were reduced by 86% for As, 15% for Cu and 33% for Cr.     

Biodegradation of catechol (2-hydroxy phenol) bearing wastewater in an UASB reactor

The present study deals with the biodegradation of catechol through co-metabolism with glucose in aqueous solution as primary substrate in an upflow anaerobic sludge blanket (UASB) reactor. Batch studies indicated that the 1000mgl(-1) glucose concentration was sufficient to cometabolize and degrade catechol in an aqueous solution up to a concentration of 1000mgl(-1). The reactor operated at 35+/-2 degrees C, and at a constant hydraulic retention time of 8h with a gradual stepwise increase in catechol concentration from 100 to 1000mgl(-1) along with glucose as a cosubstrate. The results showed that the catechol was successfully mineralized in an UASB reactor in which microbial granulation was achieved with only glucose as the substrate. The reactor showed > or = 95% COD removal efficiency with 500-1000mgl(-1)catechol concentration in the feed and a glucose concentration of 1500mgl(-1) as a cosubstrate. Similar efficiency was obtained at a constant catechol concentration of 1000mgl(-1) with 500-1000mgl(-1) glucose concentration. Once the reactor got acclimatized with catechol, higher concentrations of catechol can be mineralized with a minimum amount of glucose as the cosubstrate without affecting the performance of the UASB reactor.     

Characterization of particulate matter concentrations during controlled indoor activities

Indoor sources have been identified as a major contributor to the increase of particle concentration in indoor environments. The work presented here is a study of the characteristics of particulate matter number size distribution and mass concentration under controlled indoor activities in a laboratory room. The objective is to characterize particulate matter concentrations indoors resulted under the influence of specific sources. Measurements were performed in an empty laboratory (period September–October 2006) using a GRIMM SMPS+C system (particle size range between 11.1 and 1083.3 nm), a DustTrak Aerosol Monitor (TSI) and a P-Trak Ultrafine Particle Counter (TSI). The studied indoor activities included candle burning, hot plate heating, water boiling, onion frying, vacuuming, hair drying, hair spraying, smoking and burning of incense stick. The AMANpsd computer algorithm was used to evaluate the modal structure of measured particle number size distribution data. Furthermore, the change of the particle number size distribution shape under the influence of different emission sources was studied versus time. Finally the particle emission rates were computed. High particle number concentrations were observed during smoking, onion frying, candle burning and incense stick burning. The highest particle mass concentrations were measured during smoking and hair spraying. The shift of the particle size distribution to larger diameters suggests the presence of strong coagulation effect during candle burning, incense stick burning, smoking and onion frying. The size distribution was mainly bimodal during onion frying and candle burning, whereas the size distribution remained unimodal during incense stick burning and smoking experiments.     

Cadmium (Cd2+) removal by nano zerovalent iron: surface analysis, effects of solution chemistry and surface complexation modeling

Nano zerovalent iron (nZVI) is an effective remediant for removing various organic and inorganic pollutants from contaminated water sources. Batch experiments were conducted to characterize the nZVI surface and to investigate the effects of various solution properties such as pH, initial cadmium concentration, sorbent dosage, ionic strength, and competitive ions on cadmium removal by nZVI. Energy-dispersive X-ray and X-ray photoelectron spectroscopy results confirmed removal of Cd²⁺ ions by nZVI through adsorption. Cd²⁺ adsorption decreased in the presence of competitive cations in the order: Zn²⁺?>?Co²⁺?>?Mg²⁺?>?Mn²⁺?=?Cu²⁺?>?Ca²⁺?>?Na²⁺?=?K⁺. Higher concentrations of Cl^? significantly decreased the adsorption. Cadmium removal increased with solution pH and reached a maximum at pH 8.0. The effects of various solution properties indicated Cd²⁺ adsorption on nZVI to be a chemisorption (inner-sphere complexation) process. The three surface complexation models (diffuse layer model, constant capacitance model, and triple layer model) fitted well to the adsorption edge experimental data indicating the formation of nZVI–Cd bidentate inner-sphere surface complexes. Our results suggest that nZVI can be effectively used for the removal of cadmium from contaminated water sources with varying chemical conditions.     

Some Heavy-Metal Pollutants in the Air of Naples

ABSTRACT

In this paper, assumptions regarding future land use as a key uncertainty is considered and its impact on risk analysis for contaminated sites is assessed. Risks are assessed for two land use scenarios (current-use industrial and future-use residential) using probabilistic models that incorporate uncertainty and variability in the exposure parameters. Residual risks are calculated for both industrial and residential cleanup standards. A Superfund site in northern California is considered.

In general, for the unremediated case, the future-use residential scenarios produce larger risks (1 to 3 orders of magnitude) than current- (continued) use industrial scenarios. For the Superfund site studied, the residual risks calculated for the remedy selected was not sufficiently protective of future-use residents in that it did not meet .S. Environmental Protection Agency (EPA) risk goals, but was protective of current-use workers, even though the cleanup criteria were based on residential use. Alternative risk management practices, such as deed restrictions, can be used in such cases.     

Laboratory and Field Evaluation of Measurement Methods for One-Hour Exposures to O3, PM25, and CO

ABSTRACT

While researchers have linked acute (less than 12-hr) ambient O₃, PM₂₅, and CO concentrations to a variety of adverse health effects, few studies have characterized short-term exposures to these air pollutants, in part due to the lack of sensitive, accurate, and precise sampling technologies. In this paper, we present results from the laboratory and field evaluation of several new (or modified) samplers used in the “roll-around” system (RAS), which was developed to measure 1-hr O₃, PM₂₅, and CO exposures simultaneously. All the field evaluation data were collected during two sampling seasons: the summer of 1998 and the winter of 1999.

To measure 1-hr O₃ exposures, a new active O₃ sampler was developed that uses two nitrite-coated filters to measure O₃ concentrations. Laboratory chamber tests found that the active O₃ sampler performed extremely well, with a collection efficiency of 0.96 that did not vary with temperature or relative humidity (RH). In field collocation comparisons with a reference UV photometric monitor, the active O₃ sampler had an effective collection efficiency ranging between 0.92 and 0.96 and a precision for 1-hr measurements ranging between 4 and 6 parts per billion (ppb). The limits of detection (LOD) of this method were 9 ppb-hr for the chamber tests and ~16 ppb-hr for the field comparison tests.

PM_2.5 and CO concentrations were measured using modified continuous monitors—the DustTrak and the Langan, respectively. A size-selective inlet and a Nafion dryer were placed upstream of the DustTrak inlet to remove particles with aerodynamic diameters greater than 2.5 um and to dry particles prior to the measurements, respectively. During the field validation tests, the DustTrak consistently reported higher PM_2.5 concentrations than those obtained by the collocated 12-hr PM_{2 5} PEM samples, by approximately a factor of 2. After the DustTrak response was corrected (correction factor of 2.07 in the summer and 2.02 in the winter), measurements obtained using these methods agreed well with R² values of 0.87 in the summer and 0.81 in the winter. The results showed that the DustTrak can be used along with integrated measurements to measure the temporal and spatial variation in PM_{2 5} exposures. Finally, during the field validation tests, CO concentrations measured using the Langan were strongly correlated with those obtained using the reference method when the CO levels were above the LOD of the instrument [~1 part per million (ppm)].     

Green method of stemming the tide of invasive marine and freshwater organisms by natural filtration of shipping ballast water

Environmental Science and Pollution Research - Marine and freshwater pollution caused by transport of invasive species in shipping ballast water is a major global problem and will increase in...     

Glyphosate input modifies microbial community structure in clear and turbid freshwater systems

Since it was commercially introduced in 1974, glyphosate has been one of the most commonly used herbicides in agriculture worldwide, and there is growing concern about its adverse effects on the environment. Assuming that glyphosate may increase the organic turbidity of water bodies, we evaluated the effect of a single application of 2.4?±?0.1 mg l^?1 of glyphosate (technical grade) on freshwater bacterioplankton and phytoplankton (pico, micro, and nanophytoplankton) and on the physical and chemical properties of the water. We used outdoor experimental mesocosms under clear and oligotrophic (phytoplanktonic chlorophyll a?=?2.04 μg l^?1; turbidity?=?2.0 NTU) and organic turbid and eutrophic (phytoplanktonic chlorophyll a?=?50.3 μg l^?1; turbidity?=?16.0 NTU) scenarios. Samplings were conducted at the beginning of the experiment and at 1, 8, 19, and 33 days after glyphosate addition. For both typologies, the herbicide affected the abiotic water properties (with a marked increase in total phosphorus), but it did not affect the structure of micro and nanophytoplankton. In clear waters, glyphosate treatment induced a trend toward higher bacteria and picoeukaryotes abundances, while there was a 2 to 2.5-fold increase in picocyanobacteria number. In turbid waters, without picoeukaryotes at the beginning of the experiment, glyphosate decreased bacteria abundance but increased the number of picocyanobacteria, suggesting a direct favorable effect. Moreover, our results show that the impact of the herbicide was observed in microorganisms from both oligo and eutrophic conditions, indicating that the impact would be independent of the trophic status of the water body.