Electron donor capacity of reducing dissolved organic matter from crop residue decomposition as probed by chronoamperometry

Reducing dissolved organic matters (RDOMs) from the anaerobic decomposition of crop residue can greatly affect the physicochemical and biological properties of soils. Electrochemical methods that can effectively protect them from oxidation and rapidly obtain results, such as differential pulse voltammetry (DPV), have been applied to qualitatively analyzing properties of RDOMs. However, the donated amount of electrons from RDOMs as a capacity factor may be more crucial for evaluating their important roles. For the first time, matured chronoamperometry (CA) was applied to quantitatively determining the electron donor capacities of RDOMs in crop residue management. The electron donor capacities of RDOMs from green manure were much higher than those from rice straw, which indicated that the former had greater effect on the redox status and reactions of soil. Chronoamperometry was proposed as a practical and effective method to quantitatively characterize RDOMs from residue decomposition.     

The control effect of fungicide pyraclostrobin against freckle disease of banana and its residue dynamics under field conditions

ABSTRACT

Fungicide pyraclostrobin has been widely employed to control plant diseases by inhibiting the mitochondrial respiration of pathogenic fungi. Due to its broad spectrum, the extensive use of pyraclorstrobin was reported to cause emerging resistance on crops. Here, we evaluated the control effect of 250 g L^?1 of pyrachlostrobin suspension concentrate (SC) against freckle disease (caused by Phyllosticta spp) on banana. Meanwhile, the dissipation and residue dynamics of pyraclostrobin in banana and soil under field conditions were determined by high performance liquid chromatography (HPLC) with DAD detection in different locations. The analytical method was validated using spiked samples at three levels, which indicated the recoveries ranged from 92.0% to 99.0% with relative standard deviations (RSDs) below 5%, providing a sensitive, precise and reliable method to monitor pyraclostrobin in banana fruit and soil. The dissipation of pyraclostrobine followed the first-order kinetics and its half-lives were 5.25 to 9.90 days. In addition, the terminal residues of pyraclostrobin in banana, banana sarcocarp and soil were below the maximum residue limit (MRL) (0.02 mg kg^?1) after a pre-harvest interval (PHI) of 42 days, which suggesting that the use of pyraclostrobin at recommended dosages was safe to banana and the environment. In summary, we demonstrated the integrated evaluation on the disease control capacity of pyraclostrobin and its environmental behavior on banana, aiming to provide solid and basic data for the safe use of fungicide pyraclostrobin.     

改良剂与植被联合修复对赤泥团聚体养分和微生物特性的影响

改良剂与植被联合修复是促进赤泥土壤化的关键,但其对赤泥团聚体中养分和微生物特性的影响尚不清晰。通过开展盆栽修复实验探究改良剂 (磷石膏、木醋液、鱼粪、菌渣) 与黑麦草联合修复对赤泥团聚体中养分、酶活性、微生物群落空间分异特征的影响。结果表明,在改良剂与植被联合修复赤泥后,大团聚体 (>0.25 mm) 和微团聚体 (<0.25 mm) 占比分别减少和增加。团聚体中有机质、养分质量分数、酶活性及微生物群落Alpha多样性指数显著增加 (P<0.05) ,且主要分布于<1 mm团聚体。此外,团聚体养分、酶活性、微生物群落间呈显著正相关 (P<0.05) 。本研究结果可为深入了解赤泥土壤化过程中养分迁移转化机理及修复植物的养分自维持机制提供参考。     

云南某铬渣污染场地土壤修复工程实例

该工程一期对云南省牟定县境内某关停企业原址内受六价铬及砷污染土壤进行了修复治理,修复面积约11 680 m2,土方量共计2.62万m3。工程采用异位还原稳定化对重金属污染土壤进行了无害化处理,所用还原稳定化药剂为某环境技术公司自主研发的硫系和铁系稳定化药剂。无害化处理后的近3万m3土壤采用安全填埋进行处置。     

Determination of disulfoton and permethrin residues in an organic soil and their translocation into lettuce,onion and carrot 1

Abstract

The residues of disulfoton and permethrin in an organic soil and in vegetables grown in soil treated with a granular formulation of the pesticides were determined by gas chromatography. The residues were removed from soil or plant samples by successive extractions with acetone and hexane. Permethrin persisted in the soil for the initial 28 days and declined slowly during the rest of the season but disulfoton after persisting for one week at the applied concentration was degraded in the next two weeks. The insecticides did not translocate into the edible parts of the vegetables but were present in the root system of onion and lettuce. Carrot and lettuce yields were not significantly different from those of the controls but onion yields were substantially decreased by the use of per‐methrin.     

热解条件对茶叶渣生物炭特性及镉污染土壤钝化效果的影响

以泡饮过的废弃茶叶为实验原料,通过不同热解温度（300、400、500和600℃）和热解时间（1 h和2 h）制备生物炭,探讨不同热解条件对茶叶渣生物炭（TSBC）的特性及其对镉（Cd）污染土壤钝化效果的影响。结果表明：热解温度的升高可明显增加TSBC的pH和比表面积,降低生物炭的产率、电导率和表面官能团的数量,使TSBC具有弱碱性、较大比表面积和较强的稳定性,对改良酸性土壤和吸附重金属存在一定潜力;而热解时间对其特性没有明显差异,与对照组相比,添加TSBC明显增加了Cd污染土壤的pH、有机碳（SOC）和可溶性有机碳（DOC）含量,但随着制备温度的升高,Cd污染土壤中SOC和DOC增加幅度逐渐降低。添加TSBC显著降低Cd污染土壤中可交换态镉的比例,当热解温度为500~600℃时降幅最显著,其下降比例与对照相比最高可达25.56%;残渣态镉比对照增加了0.88~1.18倍。因此,TSBC对镉污染土壤有较好的钝化效果,这为重金属污染土壤的修复和生活废弃物的资源化利用提供了理论依据。     

Impact of a proposed revision of the IESTI equation on the acute risk assessment conducted when setting maximum residue levels (MRLs) in the European Union (EU): A case study

ABSTRACT

Proposals to update the methodology for the international estimated short-term intake (IESTI) equations were made during an international workshop held in Geneva in 2015. Changes to several parameters of the current four IESTI equations (cases 1, 2a, 2b, and 3) were proposed. In this study, the overall impact of these proposed changes on estimates of short-term exposure was studied using the large portion data available in the European Food Safety Authority PRIMo model and the residue data submitted in the framework of the European Maximum Residue Levels (MRL) review under Article 12 of Regulation (EC) No 396/2005. Evaluation of consumer exposure using the current and proposed equations resulted in substantial differences in the exposure estimates; however, there were no significant changes regarding the number of accepted MRLs. For the different IESTI cases, the median ratio of the new versus the current equation is 1.1 for case 1, 1.4 for case 2a, 0.75 for case 2b, and 1 for case 3. The impact, expressed as a shift in the IESTI distribution profile, indicated that the 95th percentile IESTI shifted from 50% of the acute reference dose (ARfD) with the current equations to 65% of the ARfD with the proposed equations. This IESTI increase resulted in the loss of 1.2% of the MRLs (37 out of 3110) tested within this study. At the same time, the proposed equations would have allowed 0.4% of the MRLs (14 out of 3110) that were rejected with the current equations to be accepted. The commodity groups that were most impacted by these modifications are solanacea (e.g., potato, eggplant), lettuces, pulses (dry), leafy brassica (e.g., kale, Chinese cabbage), and pome fruits. The active substances that were most affected were fluazifop-p-butyl, deltamethrin, and lambda-cyhalothrin.     

Chlorpyrifos degradation in a biomixture of biobed at different maturity stages

The biomixture is a principal element controlling the degradation efficacy of the biobed. The maturity of the biomixture used in the biobed affects its overall performance of the biobed, but this is not well studied yet. The aim of this research was to evaluate the effect of using a typical composition of Swedish biomixture at different maturity stages on the degradation of chlorpyrifos. Tests were made using biomixture at three maturity stages: 0 d (BC0), 15 d (BC15) and 30 d (BC30); chlorpyrifos was added to the biobeds at final concentration of 200, 320 and 480 mg kg⁻¹. Chlorpyrifos degradation in the biomixture was monitored over time. Formation of TCP (3,5,6-trichloro-2-pyrinidol) was also quantified, and hydrolytic and phenoloxidase activities measured. The biomixture efficiently degraded chlorpyrifos (degradation efficiency >50%) in all the evaluated maturity stages. However, chlorpyrifos degradation decreased with increasing concentrations of the pesticide. TCP formation occurred in all biomixtures, but a major accumulation was observed in BC30. Significant differences were found in both phenoloxidase and hydrolytic activities in the three maturity stages of biomixture evaluated. Also, these two biological activities were affected by the increase in pesticide concentration. In conclusion, our results demonstrated that chlorpyrifos can be degraded efficiently in all the evaluated maturity stages.     

Long-Term Monitoring of Scots Pine Litter Decomposition Rates Throughout Sweden Indicates Formation of a More Recalcitrant Litter in the South

Decomposition studies were carried out at sites throughout Sweden, including the four Integrated Monitoring sites. Scots pine needle litterbag weight loss measurements over 3 or 5 years were determined at 26 sites and repeated up to 27 times, depending on the site. Humus layer respiration rates were determined for 20 sites in 1987–1989 and repeated in 2007–2008. Partial Least Squares (PLS) regression was used to elucidate the relative importance of climatic and soil factors. Annual needle weight losses decreased only slowly (20–10%) over 3–5 years for all northern (>60°N) sites but decreased sharply from 30 to 10% in the third year in southern (<60°N) sites. Respiration rates of southern sites were less (40% on average) than those of northern sites. Humus layer N was positively correlated to needle weight loss during the first and the second years, but negatively correlated in the third year and to respiration rates. The results indicated that litter formed in southern Sweden became more recalcitrant in later stages of decomposition compared to litter produced in northern Sweden.     

Kresoxim methyl dissipation kinetics and its residue effect on soil extra-cellular and intra-cellular enzymatic activity in four different soils of India

The rate of degradation of kresoxim methyl and its effect on soil extra-cellular (acid phosphatase, alkaline phosphatase and β-glucosidase) and intra-cellular (dehydrogenase) enzymes were explored in four different soils of India. In all the tested soils, the degradation rate was faster at the beginning, which slowed down with time indicating a non-linear pattern of degradation. Rate of degradation in black soil was fastest followed by saline, brown and red soils, respectively and followed 1st or 1st + 1st order kinetics with half-life ranging between 1–6 days for natural soil and 1–19 days for sterile soils. The rate of degradation in natural against sterilized soils suggests that microbial degradation might be the major pathway of residue dissipation. Although small changes in enzyme activities were observed, kresoxim methyl did not have any significant deleterious effect on the enzymatic activity of the various test soils in long run. Simple correlation studies between degradation percentage and individual enzyme activities did not establish any significant relationships. The pattern and change of enzyme activity was primarily due to the effect of the incubation period rather than the effect of kresoxim methyl itself.     

Odor dispersion modeling with CALPUFF: Case study of a waste and residue treatment incineration and utilization plant in Kocaeli,Turkey

This study addresses the odor problem at a waste and residue treatment incineration and utilization plant located within the borders the Alikahya district of the Kocaeli province in Turkey. In the first stage of the study, odor measurements were made at designated sampling points, while in the second stage, odor concentrations were determined at the receptor points through dispersion modelling using a USEPA (United States Environmental Protection Agency) certified long-range (>50 km) CALPUFF lagrangian puff model. In the final stage, an analysis of the predicted and observed values was carried out using such statistical methods as geometric mean bias (MG), geometric variance (VG) and fractions of predictions within a factor of two observations (FAC2).

During the modelling study, the highest one-hour concentration level was found to be 1868.10 OU (Odor Units), and the 24-hour concentration level was found to be 1316 OU, representing a decrease of approximately 30 percent. According to the measurement made, the maximum concentration value was 2455 OU. Odor measurements were carried out at 13 points within the area in order to assess the prediction results. When the results were assessed using the MG, VG and FAC2 statistical methods, it was observed that an acceptable model performance was not achieved for the whole sampling point. When the reason for this was investigated, it was concluded that the observed values were lower than the predicted values due to the fact on the measurement days, the odor was dispersed by wind. It was further concluded that the observed values were higher than the predicted values as a result of odors emitted by other plants in the area. When the measurements in residential areas were examined to identify the effect of the odors, it was determined that although the primary density of settlement is to the southwest of the plant, it was not this area that was affected most, but rather the area to the northeast, where there is a lower settlement density.     

Ozonation of azo dye Acid Red 14 in a microporous tube-in-tube microchannel reactor: decolorization and mechanism

Despite the great success of time-weighted average passive sampling of hydrophobic contaminants, such as PCBs and PAHs, the sampling of polar organic compounds still presents a challenge because the equilibrium between water and most sampling phases is attained in a relatively short time. In this study, we proposed a new time-integrative sampler using in situ solvent extraction (TISIS) for polar organic chemicals. The sampler was composed of a 15 cm poly(dimethylsiloxane) (PDMS) tubing, with an internal diameter of 0.5 mm and wall thickness of 0.5 mm, through which an extraction solvent (acetonitrile) was passed. Four polar organic contaminants, caffeine, atrazine, diuron and 17α-ethynylestradiol, were chosen for the evaluation of the performance of the sampler. Without the use of in situ solvent extraction, the PDMS tubing when exposed to a constant aqueous concentration of the four model compounds was able to linearly accumulate those compounds for less than 12 h and equilibrium between the PDMS tubing and water was attained in 2 d under our laboratory conditions. However, TISIS when exposed to a constant aqueous concentration was able to linearly accumulate all the model compounds without any exposure time limitation. The measured sampling rates at three different extraction flow rates (0.2, 0.5, 1.5 mL min⁻¹) were similar, regardless of the chemicals, indicating that the overall mass transfer from aqueous solution to the extraction solvent was most likely dominated by partitioning to the PDMS tubing and the internal diffusion within PDMS. In addition, a pulsed exposure experiment confirmed that TISIS operated in a time-integrative mode when the environmental concentration was highly fluctuated.     

地下水曝气修复技术现场试验与应用研究进展

结合近年来国内外地下水曝气修复现场工程实践,对原位曝气的设计、操作和监测技术进行了全面的综述。对原位设计中的相关参数进行了整理分析,给出了合理取值范围,并探讨了不同场地条件下的应对方法。发展新的监测技术(如示踪技术、新型传感器等)能使曝气系统的工作性能得到更有效的监测,对于曝气修复工程现场监测新技术进行了系统的归纳和总结。此外,对现场曝气修复效果影响因素如污染物类型、曝气方式、曝气井数量、最大生物降解速率、土体孔隙率和含水层有机碳含量等进行了分析,以利于实际操作工艺的优化。最后对未来地下水曝气修复现场试验研究需开展的工作进行了展望。     

Public participation in municipal planning as a tool for coastal management: case studies from western Sweden

This article analyses four main models of participation in Swedish natural resource management and assesses strengths and weaknesses of one model (participation in physical/spatial planning) based on empirical studies of coastal resource conflicts in two Swedish west coast municipalities. In comparison to other administrative and planning procedures, physical planning offers possibilities to coordinate land and water management across sectors and resources and to broaden stakeholder participation. Local influence on coastal management increases with participation beyond the statutory minimum requirements, although management frameworks and practice of participation need to be developed further. Besides educating professionals and experimenting with combinations of existing procedures, in the long run an adaptation of legislation to the requirements of integrated and sustainable coastal management will be necessary.     

Oxidation of a PAH polluted soil using modified Fenton reaction in unsaturated condition affects biological and physico-chemical properties

A batch experiment was conducted to assess the impact of chemical oxidation using modified Fenton reaction on PAH content and on physico-chemical and biological parameters of an industrial PAH contaminated soil in unsaturated condition. Two levels of oxidant (H₂O₂, 6 and 65 g kg⁻¹) and FeSO₄ were applied. Agronomic parameters, bacterial and fungal density, microbial activity, seed germination and ryegrass growth were assessed. Partial removal of PAHs (14% and 22%) was obtained with the addition of oxidant. The impact of chemical oxidation on PAH removal and soil physico-chemical and biological parameters differed depending on the level of reagent. The treatment with the highest concentration of oxidant decreased soil pH, cation exchange capacity and extractable phosphorus content. Bacterial, fungal, and PAH degrading bacteria densities were also lower in oxidized soil. However a rebound of microbial populations and an increased microbial activity in oxidized soil were measured after 5 weeks of incubation. Plant growth on soil treated by the highest level of oxidant was negatively affected.     

Elemental levels in tree-bark and epiphytic-lichen transplants at a mixed environment in mainland Portugal, and comparisons with an in situ lichen

Samples of Platanus hybrida Brot. bark and Flavoparmelia caperata (L.) Hale thalli, from a clean area in northern Portugal (Bai?o), were transplanted into an exposure location at the south-western Atlantic coast, impacted by urban-industrial emissions (Sines), for a 10-month long experiment. Bark pieces were confined into nylon bags (2-mm mesh), and lichen thalli kept with their bark substrate (Pinus pinaster (Ait.) Sol.). Every two months, a double set of transplants (one for bark, one for lichens) was brought back into the laboratory, together with native samples of Evernia prunastri (L.) Ach. Following suitable cleansing and preparation procedures, field samples were put through INAA for elemental assessment. The results indicate that, regardless of signal magnitude, (1) concentrations in bark and lichen transplants are significantly correlated with atmospheric deposition for an appreciable number of elements; (2) there are a number of significant correlations between transplanted and native samples, and again between the latter and the deposition; and (3) the elements with biological patterns that follow the deposition in either transplanted or native samples (Co, V) are the very ones whose bioaccumulation seems to benefit from an alternation of wet-dry periods, which fits the precipitation record of the test site during the exposure term.     

先锋草本植物凋落物源溶解性有机质对典型汞铊矿废渣中重金属释放特征的影响

先锋草本植物广泛应用于尾矿堆场生态恢复,其凋落物分解是尾矿中溶解性有机质(DOM)的重要来源。然而,先锋草本植物凋落物源DOM对尾矿中重金属释放特征的影响尚不清晰。本研究以典型汞铊矿废渣及三叶草凋落物为研究对象,通过开展批次培养实验探讨了三叶草凋落物源DOM对废渣中重金属(Hg、As、Sb、Tl)释放特征的影响。结果表明,三叶草凋落物源DOM的成分主要为类络氨酸类物质、陆生类腐殖质物质和微生物类腐殖质物质。DOM的添加明显促进废渣中Hg和As的释放,抑制Tl和Sb的释放,浸出液中重金属的浓度依次为As>Tl>Hg>Sb。DOM的添加有利于废渣中Hg(Ⅱ)的溶出,促进废渣中As(Ⅴ)还原为As(Ⅲ)。主成分和相关性分析结果表明,DOM的自身组分及其对环境条件(pH、Eh)的改变是影响废渣重金属释放特征的主要因素。以上研究结果可为深入认识开展生态修复的废渣堆场上重金属的地球化学过程及环境风险提供参考。     

Sources of Volatile Organic Compounds in a University Building

A total of 34 volatile organic compounds (VOCs) were measured in the indoor of laboratories, offices and classrooms of the Chemical Engineering Department of Hacettepe University in Ankara in 2 week-day passive sampling campaigns. The average concentrations ranged from 0.77 to 265 μg m^?3 at the different indoor sites, with the most abundant VOC found to be toluene (119.6 μg m^?3), followed by styrene (21.24 μg m^?3), 2-ethyltoluene (17.11 μg m^?3), n-hexane (10.21 μg m^?3) and benzene (9.42 μg m^?3). According to the factor analysis, the evaporation of solvents used in the laboratories was found to be the dominant source.     

Deterioration of bioplastic carrier bags in the environment and assessment of a new recycling alternative

Increasing environmental concerns and the introduction of technologies based on renewable resources have stimulated the replacement of persistent petroleum-derived plastics with biodegradable plastics from biopolymers. As a consequence, a variety of products are currently manufactured from bioplastic, including carrier bags. This series of studies investigated the deterioration of carrier bags made with Mater-Bi (MB), a starch-based bioplastic, in soil, compost and two aquatic ecosystems, a littoral marsh and seawater. Results from the laboratory study indicated that bioplastic carrier bags were rapidly deteriorated in soil and compost. After three months of incubation, weight loss of specimens was of 37% and 43% in soil and compost, respectively. Conversely, little deterioration was observed in specimens buried in soil under field conditions or exposed to water of a littoral marsh and of the Adriatic Sea. These findings were consistent with the greater number of bacteria and especially fungi capable of degrading MB that were recovered from soil and compost with respect to the two aquatic ecosystems. Considering that a variety of microbial isolates are capable of using MB as a source of carbon, a new alternative to recycle these MB-based carrier bags was explored. More specifically, starchy residues from bags were fermented by the fungus Rhizopus oryzae to produce up to 35 mg of lactic acid per g of bag residues.     

Bivalve mollusks in metal pollution studies: From bioaccumulation to biomonitoring

Contemporary environmental challenges have emphasized the need to critically assess the use of bivalve mollusks in chemical monitoring (identification and quantification of pollutants) and biomonitoring (estimation of environmental quality). Many authors, however, have considered these approaches within a single context, i.e., as a means of chemical (e.g. metal) monitoring. Bivalves are able to accumulate substantial amounts of metals from ambient water, but evidence for the drastic effects of accumulated metals (e.g. as a TBT-induced shell deformation and imposex) on the health of bivalves has not been documented. Metal bioaccumulation is a key tool in biomonitoring; bioavailability, bioaccumulation, and toxicity of various metals in relation to bivalves are described in some detail including the development of biodynamic metal bioaccumulation model. Measuring metal in the whole-body or the tissue of bivalves themselves does not accurately represent true contamination levels in the environment; these data are critical for our understanding of contaminant trends at sampling sites. Only rarely has metal bioaccumulation been considered in combination with data on metal concentrations in parts of the ecosystem, observation of biomarkers and environmental parameters. Sclerochemistry is in its infancy and cannot be reliably used to provide insights into the pollution history recorded in shells. Alteration processes and mineral crystallization on the inner shell surface are presented here as a perspective tool for environmental studies.