Pendimethalin and oxyfluorfen degradation under two irrigation conditions over four years application

A four-year field study was conducted to determine the effect of pluviometric conditions on pendimethalin and oxyfluorfen soil dynamics. Adsorption, dissipation and soil movement were studied in a sandy loam soil from 2003 to 2007. Pendimethalin and oxyfluorfen were applied every year on August at 1.33 and 0.75 kg ha^?1, respectively. Herbicide soil concentrations were determined at 0, 10, 20, 40, 90 and 340 days after application (DAA), under two pluviometric regimens, natural rainfall and irrigated (30 mm every 15 days during the first 90 DAA). More than 74% of the herbicide applied was detected at the top 2.5 cm layer for both herbicides, and none was detected at 10 cm or deeper. Pendimethalin soil half-life ranged from 10.5 to 31.5 days, and was affected mainly by the time interval between application and the first rain event. Pendimethalin soil residues at 90 DAA fluctuated from 2.5 to 13.8% of the initial amount applied, and it decreased to 2.4 and 8.6% at 340 DAA. Oxyfluorfen was more persistent than pendimethalin as indicated by its soil half-life which ranged from 34.3 to 52.3 days, affected primarily by the rain amount at the first rainfall after application. Oxyfluorfen soil residues at 90 DAA ranged from 16.7 to 34.8% and it decreased to 3.3 and 17.9% at 340 DAA. Based on half-life values, herbicide soil residues after one year, and soil depth reached by the herbicides, we conclude that both herbicides should be considered as low risk to contaminate groundwater. However, herbicide concentration at the top 2.5 cm layer should be considered in cases where runoff or soil erosion could occur, because of the potential for surface water contamination.     

自燃煤矸石山覆盖材料压缩及压实特性实验

自燃煤矸石山表面构建覆盖层,需要具备一定的低渗透性能以有效阻隔空气,防止煤矸石山内部发生自燃。本研究通过室内实验,测定煤矸石山构建覆盖层涉及的碾压材料包括黄土、粉煤灰及掺有粉煤灰的混合土样的界限含水率、一维压缩特性及压实特性,揭示和分析7种覆盖材料配方的压缩压实特性,表明覆盖材料通过碾压可有效阻隔空气,起到阻燃作用;将粉煤灰掺人到一般黄土材料中,可减缓混合土样击实曲线的陡峭性,从而降低材料在碾压中对含水率的敏感度。实验旨在为进行煤矸石山覆盖层碾压提供科学的实验数据及设计参数。     

Application of nanobalance technique and principal component analysis for detection of the soil fumigant Telone residues in the air

Quartz crystal nanobalance (QCN) technique is considered as a powerful mass sensitive sensor for monitoring of materials in the sub-nanogram level. In the current study, a method based on QCN technique developed to determine Telone in air. Various coating materials including methyl phenyl silicon, 75% phenyl (OV25) and molecularly imprinted polymer (MIP) were employed. The frequency shift of OV25-modified quartz crystal was found to be linear against organohalogen compounds [Telone (soil fumigant), Koril (Herbicide), Endosulfan (organochlorine insecticide) and Chloroform (solvent)] concentrations in the range of 2.4 to 48 mg L^?1 for Telone vapor and 4.8–24 mg L^?1 for three other vapors. The correlation coefficients for Telone, Koril, Endosulfan and Chloroform were 0.992, 0.996, 0.989 and 0.991, respectively. The principal component analysis was also utilized to process the frequency response data of the organic vapors. Using principal component analysis, it was found that more than 93.85% of the data variance could still be explained by use of two principal components (PC1 and PC2). Subsequently, the successful discrimination of Telone and other compounds was quite possible through the principal component analysis of the transient responses of the OV25-modified electrode. In the second method, a molecularly imprinted polymer-coated sensor for Telone was developed. Molecularly imprinted polymer coated quartz crystal (MIP-QCN) showed a selective response to Telone and gave a linear relationship between frequency shift and amount of Telone from 1 to 48 mg L^?1. In this investigation, the proficiency of MIP-QCN and OV25-modified QCN sensors were compared.     

The effects of soil and Trifolium repens (white clover) on the fate of estrogen

In this study, we investigated the behavior of estrogens in the rhizosphere of white clover (Trifolium repens, clover hereafter) with two different pot tests, using soil and agar as growth media. In a pot test using agar spiked with estrogen, the estrogen concentration in the agar with clover decreased to non-detectable levels within one month, while in the agar without clover, 60% of initially added estrogen remained after one month. The half-lives of estrone (E1) and 17β -estradiol (E2) in the agar with clover were 2.4–3.8 and 13.2 d, respectively. The dissipation of E1 followed first-order rate law, while that of E2 fitted a zero-order reaction, indicating that they had different mechanisms of dissipation from agar. In the soil pot test, the behavior of E1 and E2 was not influenced by clover. An initial rapid decrease in the amount of estrogen extracted by methanol/acetic acid was followed by persistence for 1–3 months, regardless of presence of clover. Moreover, in three weeks E1 and E2 were only partly degraded by microbes extracted from the soil used in the pot test. In this study, abiotic degradation of estrogens and sorption of estrogen to soil, rather than the effects of soil microbes and clover, contributed to the initial rapid dissipation of estrogens in the soil. However, the results of the agar pot test suggested that vegetation such as clover may significantly contribute to removal of estrogens when estrogens in aqueous phase are discharged with surface runoff and preferential flow after heavy rain in agricultural fields, or when present in soils with low estrogen sorptivity.     

Evaluation of the field dissipation of fungicides and insecticides used on fruit bearing trees in northern Italy

The dissipation of the fungicides captan, cyprodinil, fludioxonil, dithianon, and tebuconazole and of the insecticides chlorpyrifos, fenitrothion, and malathion was studied, following a single treatment of different cultivars of pears, apples, and peaches. The study was conducted in northern Italy, over two successive growing seasons (2004 and 2005). The treatments were performed by the farmers involved, in line with their usual practice. At various time intervals from treatment to harvest, representative samples of fruit were collected and analyzed for pesticide residues. In some cases, concentrations lower than the maximum residue levels (MRLs) were found immediately after treatment. In all trials a rapid decline in pesticide concentrations was observed leading to residues at harvest greatly below the MRLs.     

Sorption and degradation of neonicotinoid insecticides in tropical soils

ABSTRACT

Neonicotinoids are the most widely applied class of insecticides in cocoa farming in Ghana. Despite the intensive application of these insecticides, knowledge of their fate in the Ghanaian and sub-Saharan African environment remains low. This study examined the behavior of neonicotinoids in soils from cocoa plantations in Ghana by estimating their sorption and degradation using established kinetic models and isotherms. Studies of sorption were conducted using the batch equilibrium method on imidacloprid, thiamethoxam, clothianidin, acetamiprid and thiacloprid, while degradation of imidacloprid, thiamethoxam and their respective deuterated counterparts was studied using models proposed by the European forum for coordination of pesticide fate and their use (FOCUS). Analytes were extracted using the quick, easy, cheap, effective, rugged and safe (QuEChERS) procedure and quantified by liquid chromatography-tandem mass spectrometry (LC–MS/MS). Average recoveries were high (≥ 85%) for all analytes. The findings from the study suggest that neonicotinoid insecticides may be persistent in the soils studied based on estimated half-lives > 150 days. The study also revealed generally low-sorption coefficients for neonicotinoids in soils, largely influenced by soil organic carbon.     

液晶显示器玻璃基板回收工艺

利用无机溶液对废液晶显示屏的玻璃基板回收工艺作了初步的探索,根据回收处理的难易,简单地将废弃液晶显示屏分为3类:含树脂黑色矩阵膜的上层玻璃基板可以采用氢氧化钠直接浸泡处理、含铬黑矩阵膜的上层玻璃基板和下层玻璃基板可以先用氢氧化钠溶液浸泡去除偏光片,再用氢氟酸溶液浸泡处理。结果表明,利用无机溶液处理可以较快得到干净的玻璃基板,而且工艺简单、成本低。     

Silica nanoparticles and silver-doped silica nanoparticles induce endoplasmatic reticulum stress response and alter cytochrome P4501A activity

Engineered silica nanoparticles (SiO₂-NPs) find widespread application and may lead to exposure of humans and the environment. Here we compare the effects of SiO₂-NPs and SiO₂-NPs doped with silver (SiO₂-Ag-NPs) on survival and cellular function of human liver cells (Huh7) and Pimephales promelas (fathead minnow) fibroblast cells (FMH). In Huh7 cells we investigate effects on the endoplasmatic reticulum (ER), including ER stress, and interactions of nanoparticles (NPs) with metabolizing enzymes and efflux transporters. The NPs formed agglomerates/aggregates in cell culture media as revealed by SEM and TEM. SiO₂ and SiO₂-1% Ag-NPs were taken up into cells as demonstrated by agglomerates occurring in vesicular-like structures or freely dispersed in the cytosol. Cytotoxicity was more pronounced in Huh7 than in FMH cells, and increased with silver content in silver-doped NPs. Dissolved silver was the most significant factor for cytotoxicity. At toxic and non-cytotoxic concentrations SiO₂-NPs and SiO₂-1% Ag-NPs induced perturbations in the function of ER. In Huh7 cells NPs induced the unfolded protein response (UPR), or ER stress response, as demonstrated in induced expression of BiP and splicing of XBP1 mRNA, two selective markers of ER stress. Additionally, SiO₂-1% Ag-NPs and AgNO₃ induced reactive oxygen species. Pre-treatment of Huh7 cells with SiO₂-1% Ag-NPs followed by exposure to the inducer benzo(a)pyrene caused a significant reduced induction of CYP1A activity. NPs did not alter the activity of ABC transporters. These data demonstrate for the first time that SiO₂-NPs and SiO₂-1% Ag-NPs result in perturbations of the ER leading to the ER stress response. This represents a novel and significant cellular signalling pathway contributing to the cytotoxicity of NPs.     

Uncertainties in a Baltic Sea Food-Web Model Reveal Challenges for Future Projections

Models that can project ecosystem dynamics under changing environmental conditions are in high demand. The application of such models, however, requires model validation together with analyses of model uncertainties, which are both often overlooked. We carried out a simplified model uncertainty and sensitivity analysis on an Ecopath with Ecosim food-web model of the Baltic Proper (BaltProWeb) and found the model sensitive to both variations in the input data of pre-identified key groups and environmental forcing. Model uncertainties grew particularly high in future climate change scenarios. For example, cod fishery recommendations that resulted in viable stocks in the original model failed after data uncertainties were introduced. In addition, addressing the trophic control dynamics produced by the food-web model proved as a useful tool for both model validation, and for studying the food-web function. These results indicate that presenting model uncertainties is necessary to alleviate ecological surprises in marine ecosystem management.     

Post-Fordist transformation,the sustainability concept and social relations with nature: a case study of the Hamburg region

Following the United Nations Conference on Environment and Development, the concept of sustainability in general and of urban sustainability in particular has become increasingly significant in the course of the 1990s. Even if the environmental problems of cities are far from being solved, one can interpret this development as a change in the relationship between society and nature on both a discursive and a material level. At the same time the transition from Fordism to post-Fordism has given rise to new forms of urban entrepreneurialism, with an absolute priority to economic competitiveness on the one hand and sharpened social conflicts on the other. Looking at the case of the Hamburg region, the article discusses the interaction of these processes. Contrary to the understanding of sustainability as a broadly accepted policy goal it conceptualizes sustainability as a terrain of conflict. As such, we will argue, the sustainability concept and the underlying change in social relations with nature contribute to containing the contradictions of capitalist societalization, which in the transition to post-Fordism have become more visible again. Copyright © 2002 John Wiley & Sons, Ltd.