Determination of Cd,Cr, Cu,Pb and Zn from various water samples with use of FAAS techniques after the solid phase extraction on rice bran

A facile and novel method has been developed for the determination of cadmium, chromium, copper, lead, and zinc from various water samples using FAAS. In the present investigation, a syringe was loaded with sorbent (rice bran) for the separation and enrichment of cadmium, chromium, copper, lead, and zinc, prior to their analysis by flame atomic absorption spectrometry which was described to substitute the batch and column techniques. The syringe was loaded with 2.0 g of sorbent in order to retain the analyte elements. Six milliliter of sample solution (pH 8.0 ± 0.2) was drawn into the syringe in 15 s and discharged over a period of 15 s. Then, 2.0 M HCl eluent was drawn into the syringe and ejected back to desorb the analyte elements. At the optimum conditions, the percentage recoveries of Cd, Cr, Cu, Pb, and Zn was in the range of 95.5–99.4% with SD of 0.10%. The elements could be concentrated by drawing and discharging several portions of sample successively. The detailed study of various interferences made the confirmation of the method highly selective. The risk of contamination is less than that with the column technique. The method was successfully applied for the determination of Cd, Cr, Cu, Pb, and Zn in spiked and natural water samples. The results obtained are in good agreement with the reported methods at the 95% confidence level.     

The legacy of surface mining: Remediation,restoration, reclamation and rehabilitation

Surface mining is a global phenomenon. When dealing with the land disturbances caused by surface mining operations, the terms remediation, reclamation, restoration and rehabilitation (R4) are commonly used interchangeably or otherwise vaguely defined. Expectations associated with these terms may differ significantly from one stakeholder to another, however. Regulators, industry, environmental practitioners, local communities and the general public therefore stand to benefit from a precise terminology based on agreed-upon end-goals. The latter range from the avoidance of exposure to pollutants (remediation) to the full recovery of the original ecosystem (restoration). Although frequently claimed as the end-goal, restoration may often not be unachievable, because of altered hydrology, habitat fragmentation, contamination, climate change, prohibitive costs and other environmental and socio-economic boundary conditions. Mostly, the definitions of reclamation and rehabilitation may overlap in their definitions and approaches. Here we attempt the creation of a road-map that can clearly translate end-goals for each of the R4 terms. According to the definitions encountered and exposed here, reclamation, which aims to recover key ecosystem services and biogeochemical functions within a replacement ecosystem or rehabilitation, which implies a repurposing of the landscape, may be the best approaches to deal with surface mining legacies.     

Bargaining over natural resources: Governments between environmental organizations and extraction firms

We consider the resource-extraction policy of a government that is lobbied by an environmental organization and an extraction firm from foreign countries. To analyze this situation, we propose a sequential Nash bargaining solution: The government bargains with both lobbies simultaneously. Should this trilateral negotiation fail, it chooses one lobby for a bilateral negotiation. The disagreement point then is to bargain with the other lobby. Finally, should this second bilateral negotiation break down, the government chooses the welfare-maximizing policy.As long as cumulative extraction is low, such that stock-dependent extraction costs are also low and extraction profits are high, the environmental organization has a weak bargaining position, but it takes influence to reduce extraction. Once that cumulative extraction has increased so much that extraction profits are below a threshold, the bargaining positions change, and the environmental organization gets compensated by the extraction firm for not letting the trilateral negotiation fail.     

Determination of the insecticide diflubenzuron in mushrooms by kinetic method and high-performance liquid chromatographic method

In the present study, a new sensitive and simple kinetic-spectrophotometric method for the determination of the insecticide diflubenzuron [1-(4-chlorophenyl)-3-(2,6-diflubenzoil)urea] is proposed. The method is based on the inhibited effect of diflubenzuron on the oxidation of sulphanilic acid (SA) by hydrogen peroxide in phosphate buffer in presence Cu(II) ion. Diflubenzuron was determined with linear calibration graph in the interval from 0.31 to 3.1 μg mL^?1 and from 3.1 to 31.0 μg mL^?1. The optimized conditions yielded a theoretical detection limit of 0.18 μg mL^?1corresponding to 0.036 mg Kg^?1mushroom sample based on the 3S_b criterion. The RSD is 5.03–1.83 % and 2.81–0.71 % for the concentration interval of diflubenzuron 0.31–3.1 μg mL^?1and 3.1–31.0 μg mL^?1, respectively. The reaction was followed spectrophotometrically at 370 nm. The kinetic parameters of the reaction are reported, and the rate equations are suggested. The developed procedure was successfully applied to the rapid determination of diflubenzuron in spiked mushroom samples of different mushroom species. The HPLC method was used like a comparative method to verify results.     

Prediction of Total Sediment Load in Sand‐Bed Rivers in Korea Using Lateral Distribution Method

A new method for numerically predicting the total sediment load in a river is proposed. The method can be used to predict the total sediment load with information on channel geometry and slope, flow, and bed materials. The conventional method uses a 1D approach that assumes the channel has a wide rectangular shape. However, the proposed method computes depth‐averaged velocity over the width and predicts the total sediment load based on the flow computations. The new method, therefore, is expected to predict better if the flow changes significantly in the lateral direction. The proposed method was applied to three large sand‐bed rivers in Korea, where information is available regarding suspended sediment. Five formulas were tested of use in making total sediment load computations, namely Engelund‐Hansen's, Ackers‐White's, Yang's, Brownlie's, and Karim's formulas. The predicted total sediment loads are compared not only with measured data but also with results calculated using the 1D approach. Discrepancy ratios between the predicted and measured total sediment loads are given and the results are discussed.     

液相色谱质谱法测定水体及土壤中的类固醇激素

建立了水体和土壤中类固醇激素的液相色谱质谱分析方法。水样采用固相萃取方法富集,土壤样经加速溶剂萃取后由固相萃取净化和富集。处理好的样品经丹磺酰衍生化后上仪器分析。结果表明,类固醇激素在水体和土壤中的检出限分别为0.01~0.6ng/L和0.01~0.19ng/g,回收率分别为77%~97%和62%~119%,RSD小于6.04%和15.5%。该方法具有较高的准确度和精密度,适用于环境水体及土壤中类固醇激素残留的分析。     

Sequential extraction of Cs and Sr from Ain Oussera soils around Es-Salam research reactor facility

Four types of undisturbed soil in Ain Oussera region around the Es-Salam reactor facility, located in the south of Algiers, Algeria, at about 200 km, were artificially contaminated for one year with stable CsCl and SrCl₂ in order to simulate an accidental release of these elements. This study was performed using sequential extraction procedure based on Shultz method and containing six fractions. The selectivity of the extraction protocol was confirmed by analyzing some elements (Ca, C, Fe, Mn, Si and Al) designed as indicators of the targeted phases. The obtained results showed an acceptable reproducibility, in view of the coefficients of variation that were in most cases less than 15%. The results revealed a clear proportional correlation between the extracted Cs and Sr in fractions for each soil and some of soils physicochemical properties. Organic matter appears to play an important role in the soil retention, particularly for Cs where the extracted percentage exceeds to 30% in whole soils. In contrast, strontium expresses a remarkable affinity for the fraction bound to carbonates. The obtained data also indicate that the availability of Cs in the four soils is less important compared to Sr availability. This is illustrated by the higher value of extracted Sr in the easily extractible phase, including the water-soluble and the exchangeable fraction.     

超声波萃取-毛细管气相色谱法测定土壤和底质中的25种有机氯农药研究

建立了超声波萃取、Florisil柱净化,SPB-5毛细管柱分离,ECD检测器测定土壤和底质中25种有机氯农药的方法.该方法的检出限为0.079 μg/kg ～1.2 μg/kg,加标回收率为73.1％ ～ 126.5％,相对标准偏差为3.3％ ～9.7％.实验结果证明,该方法灵敏度高、精密度高,操作快速简便,满足土壤和底质中有机氯农药的测定要求.     

固相萃取-原子荧光光谱法测定土壤中的砷

采用硝酸-氢氟酸-盐酸体系微波消解土壤并结合On-Guard ⅡH柱去除消解液中重金属,原子荧光光谱法测定土壤中的砷。本方法前处理操作过程简单、省时、省力、酸用量少,砷的加标回收率为94.4％～105.6％,能够满足环境监测分析的要求。     

Pseudomonas sp. QJX-1的锰氧化特性研究

从锰矿土壤样品中分离、纯化出1株高效锰氧化细菌(QJX-1),经16S rDNA序列鉴定为Pseudomonas sp.QJX-1.研究表明,Pseudomonas sp.QJX-1含有锰氧化的必需成分多铜氧化酶基因CumA,当初始Mn2+为5.05 mg·L-1,菌密度D600为0.020时,该菌可在48 h内将Mn2+转化,且转化率高达99.4%.在寡营养条件下该菌锰氧化速率较富营养条件下有显著提高;添加石英砂滤料促使生物膜的快速形成,进而促进Mn2+的生物转化.根据研究结果推测地下水处理过程中生物锰氧化速率较快.