Effects of elevated soil copper on phenology,growth and reproduction of five ruderal plant species

The repeated use of copper (Cu) fungicides to control vine downy mildew, caused by Plasmopara viticola, has been responsible for the heavy increase of Cu concentration in the upper layers of vineyard soils. To determine the effects of elevated soil Cu on plant development, we created an artificial soil gradient with Cu enrichments ranging from 0 to 400 mg kg-1. On this gradient, and for five ruderal plant species commonly found in vineyards in southern France (Poa annua L., Dactylis glomerata L., Senecio vulgaris L., Hypochoeris radicata L., and Andryala integriflolia L.), we quantified survival, growth, and reproduction throughout one flowering season. High concentrations of Cu in the soil resulted in low survival, low total plant biomass, delay in flowering and fruiting, and low seed set. However, the effects differed among species. Furthermore, high soil Cu concentrations had contrasting effects on patterns of resource allocation depending on the plant species.     

Changes of copper speciation in maize rhizosphere soil

Chemical forms of copper in the rhizosphere and bulk soil of maize were investigated using rhizobox cultivation and sequential extraction techniques. The copper accumulations were also determined. The results demonstrated that there were continuous changes in copper fractionation within the maize rhizosphere. Initially, the amount of exchangeable copper increased before dropping below the initial level after 40 days or so. Carbonate associated copper followed a similar trend of change, but with a slower pace than the exchangeable copper. The increase in carbonate associated copper only become evident after 30 days, with the net loss occurring after 60 days. There were also initial increases in oxide bound copper as well as decreases in the organic matter associated copper, both followed by a turnover after 40-50 days. The accumulation of copper in the maize plant was found to be biomass dependent. The amount of accumulated copper absorbed in the plant material exceeded the initial quantity of the exchangeable copper in the soil, revealing a transformation from less bioavailable to more bioavailable fractions. During cultivation, decreases in redox potential and increases in pH, dissolved organic carbon (DOC), and microbial activity in the maize rhizosphere were observed. The change in copper speciation may result from root-induced changes in DOC, redox potential, and microbial activity in the rhizosphere.     

Leaching of bisphenol A (BPA) to seawater from polycarbonate plastic and its degradation by reactive oxygen species

In this study, (1) change in the concentration of bisphenol A (BPA) leached from polycarbonate (PC) tube to control water (BPA free), seawater and river water at 20 and 37 degrees C as a function of time, (2) the fate of BPA caused by addition of H(2)O(2) and Fe(3+) to seawater containing BPA leached from PC tube were assessed. BPA leached from PC tube to all water samples increased with the ascendant of temperature and with the passage of time. The BPA leaching velocity in seawater was the fastest in three samples (11 ng/day for seawater, 4.8 ng/day for river water 0.8 ng/day for control water at 37 degrees C).BPA leaching velocity from PC tube was significantly high at pH 8 (50 mM Na(2)HPO(4)) and increased dose-dependently. There was no difference in the velocity of BPA among the 50 mM phosphate-buffers at pH 6.5, 7.0 and 7.5. BPA was leached three times higher by addition of Na(+) than K(+). However, the higher the K(+) concentration, the larger the BPA leached from PC tube. Na(+) mixed with PO(4)(-) was effective on BPA leaching from PC tube, but not with SO(4)(-) or Cl(-). The results suggested that BPA leaching from PC tube would be attributed to the concentration of bibasic phosphate such as Na(2)HPO(4) and K(2)HPO(4) in water samples. BPA was degraded in both control water and seawater in the presence of radical oxygen species, but the degradation rate was lower in seawater than in control water, suggesting that anti-oxidative system exists in seawater. Neo-synthesized substance in both control water and seawater in the presence of reactive oxygen species was identified as BPA-quinone by LC-MS.     

Effect of silica sand on activation energy for diffusion of sodium ions in montmorillonite and silica sand mixture

The effect of silica sand on the diffusion of sodium ions in mixtures of montmorillonite and silica sand was studied by measuring the apparent diffusion coefficients, activation energies for diffusion, and the basal spacing of the mixed samples. These diffusion experiments suggest that the apparent diffusion coefficients of sodium ions in the mixed samples were almost the same as those of pure montmorillonite samples having the same partial dry densities of montmorillonite. The activation energy dependence for diffusion of sodium ions on the partial dry density was different between the mixed samples and the pure montmorillonite samples. The activation energy increased by adding silica sand at the partial dry density of 1.0 Mg m(-3), and decreased by adding silica sand at the partial dry densities higher than 1.2 Mg m(-3). A change in the XRD profile was observed after adding silica sand at the partial dry density of 1.6 Mg m(-3). Here, a three-water-layer hydrate state of montmorillonite was found in the mixed sample whereas only a two-water-layer hydrate state was observed in the pure montmorillonite sample. These experimental results suggest that silica sand changed the montmorillonite microstructure in the mixed samples, which then altered the sodium-ion diffusion process.     

Fate and assessment of persistent organic pollutants in water and sediment from Minjiang River Estuary,Southeast China

Persistent organochlorine compounds were analyzed in surface water, porewater and surficial sediment samples from Minjiang River Estuary, which is the first large river in Fujian Province, Southeast of China. The total concentrations of 18 organochlorine pesticides were 214.4-1819, 4541-13,699 ng/l, 28.79-52.07 ng/g in surface water, porewater and sediments (dry weight) respectively, and those of 21 polychlorinated biphenyls (PCBs) in the three phases were: 203.9-2473, 3192-10,855 ng/l, 15.14-57.93 ng/g respectively. The results showed that the concentrations of these selected organochlorine pesticides and PCBs in porewater were higher than those in surface water. It may be due to the fact that these organic hydrophobic pollutants tend to stay in the sediments, and then re-suspend from the sedimentary phase to the upper water. We have analyzed the distribution characteristics of individual organochlorine pesticide components and PCBs, and found that alpha-HCH, DDE, Heptachlor, Endosulfan II, Methoxychlor were the most common organochlorine pesticides contaminants. Considering the groups of HCHs (HCHs=alpha-HCH+beta-HCH+gamma-HCH+delta-HCH) and DDTs (DDTs=DDT+DDD+DDE), the predominance of beta-HCH, DDE in all water, porewater and sediment samples was clearly observed. This observation suggested that beta-HCH was resistant to biodegradation and the DDTs had been transformed to its metabolites, DDE and DDD, of which DDE that was more un-degradable. The PCB congeners containing 3-6 chlorines had the great preponderance in the three phase. These results were compared with those present in other estuaries and harbors. A risk assessment was evaluated for the persistent organic pollutants in the Minjiang River Estuary.     

Inactivation of fungi associated with barley grain by gaseous ozone

The use of gaseous ozone as a fungicide to preserve stored barley was studied. The effects of the following operating parameters on the fungicidal efficacy of ozone were examined: 1) the applied ozone dose, 2) ozonation time, 3) water activity of barley, and 4) temperature of barley. The effect of ozonation on germination of barley was also investigated. The experimental results showed that ozone was very effective in inactivation of fungi associated with the barley regardless of whether the fungi were in the forms of spores or mycelia. However, the mycelia were less resistant to ozone. With 5 minutes of ozonation, 96% of inactivation were achieved for spores as well as for mixtures of spores and small amount of mycelia by applying 0.16 and 0.10 mg of ozone/(g barley) x min, respectively. In addition, for sealed storage silos, inactivation of fungi continued when the ozone-containing gas was held inside the silos following a continuous ozone supply. The experimental results also revealed that increases in water activity and temperature of barley enhanced the fungicidal efficacy of ozone. Results of this study also indicated that the inactivation processes could be controlled by simply monitoring the exit ozone from the reactor instead of performing the time-consuming microbial examination. This finding would make the application of ozone in the preservation of cereal grains easier, simpler, and more practically applicable. The experimental results demonstrated that although ozonation above certain strength may reduce barley germination, inactivation of fungi was achieved with ozonation strengths far below the critical point.     

Ranking the risks of 12 major environmental pollutants that occur in Japan

The risks posed by 12 major environmental pollutants in Japan were evaluated and ranked on the same scale. These were arsenic, benzene, cadmium, chlordane, chlorpyrifos, DDTs, dioxins, formaldehyde, methylmercury, radon, toluene, and xylenes. Approximately half of these substances are carcinogenic while the other half are non-carcinogenic. We applied a risk estimation framework that can evaluate both cancer and non-cancer risks on the same scale. The framework consists of two parts: the calculation of the probability of adverse health effects, and the evaluation of the severity of the effects. In order to calculate the probability of adverse health effects, individual variabilities in exposure level, metabolizing rate, and sensitivity were taken into account. Loss of life expectancy (LLE; days) was used as a measure of severity of the adverse health effects and of the resulting risk level. The risk level of the substances in terms of LLE ranged from approximately 0.01 to 10 days. The risks from radon and formaldehyde were found to be the highest, while those from DDT and chlordane were the lowest. Our findings also suggested that the risk levels posed by non-carcinogenic substances were comparable to those posed by carcinogenic substances.     

Relevance of coplanar PCBs for TEQ emission of fluidized bed incineration and impact of emission control devices

Five fluidized bed incinerators combusting municipal solid waste were assessed for the impact of coplanar PCBs on total TEQ emission. In 17 stack measurements, the coplanar PCBs contributed on average less than 3% to total TEQ with a maximum contribution of 7.5% to total TEQ in one measurement. Differences in the design of the flue gas cooling section did not show an effect on the impact of coplanar PCBs on total TEQ. The effect of emission control devices on the impact of coplanar PCBs on the total TEQ was studied in more detail at one incinerator. The relative contribution of PCBs to total TEQ increased along the flue gas line. This was caused by a slightly higher removal efficiency for TEQ relevant PCDDs/PCDFs compared to coplanar PCBs by the bag filters and a higher destruction efficiency for PCDDs/PCDFs compared to PCBs by the SCR catalyst. Additionally, the removal efficiencies of the emission control devices (bag filters and catalyst) for other chlorinated aromatic compounds which have been proposed as TEQ indicator compounds (polychlorinated benzenes and polychlorinated phenols) were compared with those for PCDDs/PCDFs and coplanar PCBs. Removal efficiencies for polychlorinated benzenes or polychlorinated phenols considerably differed from those of PCDD/PCDF and coplanar PCBs. Implications for TEQ assessments using indicator compounds as proposed in the literature are discussed.     

The role of humic substances in chromium sorption onto natural organic matter (peat)

To elucidate mechanisms of Cr³⁺ sorption onto the unaltered solid natural organic matter, the comparative studies of this ion binding from a solution at pH 4.0 onto three selected particle size fractions: 2000–1000 μm, 630–200 μm and 63–20 μm of markedly different HS content and structure, separated by a wet sieving from an overall sample of peat (Brushwood Peat Humus) were carried out. Comparable patterns of COOH groups and CEC_t confirmed that for cation exchange capacity were responsible mainly cations connected with COO⁻ functional groups. It was though found that aliphatic acids in the solid state did not take part in Cr³⁺ binding, thus the finest studied fraction 63–20 μm of the highest contents of functional groups showed the lowest sorption capacity for Cr³⁺, while similar patterns of sorbed Cr³⁺, soluble HS content and base CEC₀ indicated that these parameters were directly interrelated. The base ion exchange processes determined by CEC₀ (with Ca²⁺ as a predominant exchangeable cation) appeared to be not the major mechanisms responsible for Cr³⁺ sorption. For this metal, strong binding to insoluble large molecular weight organic pool two- to threefold prevailed over the ion exchange processes. Very low acid desorption indicated generally low mobility of Cr³⁺-organic compounds.     

Vapour pressures, aqueous solubility, Henry's law constants and air/water partition coefficients of 1,8-dichlorooctane and 1,8-dibromooctane

New data on the vapour pressures and aqueous solubility of 1,8-dichlorooctane and 1,8-dibromooctane are reported as a function of temperature between 20 °C and 80 °C and 1 °C and 40 °C, respectively. For the vapour pressures, a static method was used during the measurements which have an estimated uncertainty between 3% and 5%. The aqueous solubilities were determined using a dynamic saturation column method and the values are accurate to within ±10%. 1,8-Dichlorooctane is more volatile than 1,8-dibromooctane in the temperature range covered (p_sat varies from 3 to 250 Pa and from 0.53 to 62 Pa, respectively) and is also approximately three times more soluble in water (mole fraction solubilities at 25 °C of 5.95 × 10⁻⁷ and 1.92 × 10⁻⁷, respectively). A combination of the two sets of data allowed the calculation of the Henry’s law constants and the air water partition coefficients. A simple group contribution concept was used to rationalize the data obtained.