Determination of commonly used herbicides in surface water using solid-phase extraction and dual-column HPLC-DAD

The present study describes the application of different solid-phase extraction techniques for the extraction, separation, and quantitative determination of 10 commonly used herbicides with different chemical structures (chlorsulfuron, diuron, bentazone, linuron, chlorpropham, fenoxoprop-ethyl, MCPA, diclofop-methyl, fluazifop-butyl, trifluraline) in water. Octadecyl (C(18)) Empore extraction disks, octadecyl (C(18)), and stryene divinylbenzene (SDB) Bond Elut Env cartridges were compared for solid-phase extraction efficiency. Herbicides were separated and quantified by reversed-phase high performance liquid chromatography with diode-array detection (HPLC-DAD) with simultaneous separation on two columns of differing polarity (C(18) and CN) to confirm identification. Analytical separation was performed simultaneously on C(18) and CN columns. Reanalysis of the sample extracts on a (cyano) CN column were used to confirm the identity of these compounds. Method optimization and validation parameters were presented in this work. Recoveries varied from 76.0% to 99.0% for C(18) disks, from 75.1% to 100.0% for C(18) cartridges, and from 54.0% to 98.0% for SDB cartridges over concentrations at 0.025--0.4 microg L(-1). The limits of detection were 0.012--0.035 microg L(-1).     

Multiscale Methodological Framework to Derive Criteria and Indicators for Sustainability Evaluation of Peasant Natural Resource Management Systems

Design and implementation of more sustainable natural resource management systems is the current objective of many research institutions, development agencies, NGOs and other stakeholders. But, how to assess whether a system is sustainable? How do we know whether the alternatives designed will increase the sustainability of the system? How to evaluate or assess the sustainability of natural resource management systems?In this paper we present a multiscale methodological framework for sustainability evaluation. The framework is based on a systems approach from which five general attributes of sustainable natural resource management systems are defined based on scale- and discipline-independent properties (productivity, stability, resilience, reliability and adaptability).A general operational strategy to derive ‘site-specific’ criteria and indicators for the attributes at different scales is also presented. This strategy is based on the definition of ‘impact scales’, at which the different stakeholders can or want to design alternatives, as well as the main stakeholders’ objectives and constraints. The application of the multiscale framework is illustrated with a case study in the Purhepecha Region of Michoacán, a peasant mountainous region in the west of Mexico. We used stakeholder consultation to identify the main objectives and constraints as well as to select criteria and indicators. The sets of criteria and indicators suggested for the different scales of analysis of the Purhepecha Region are comprehensive, yet not exhaustive, and represent the main issues related to natural resource management in the region. Further work will be directed towards the quantification of indicators at different scales and their relationships and trade-offs.     

Forecasting the number of soil samples required to reduce remediation cost uncertainty

Sampling scheme design is an important step in the management of polluted sites. It largely controls the accuracy of remediation cost estimates. In practice, however, sampling is seldom designed to comply with a given level of remediation cost uncertainty. In this paper, we present a new technique that allows one to estimate of the number of samples that should be taken at a given stage of investigation to reach a forecasted level of accuracy. The uncertainty is expressed both in terms of volume of polluted soil and overall cost of remediation. This technique provides a flexible tool for decision makers to define the amount of investigation worth conducting from an environmental and financial perspective. The technique is based on nonlinear geostatistics (conditional simulations) to estimate the volume of soil that requires remediation and excavation and on a function allowing estimation of the total cost of remediation (including investigations). The geostatistical estimation accounts for support effect, information effect, and sampling errors. The cost calculation includes mainly investigation, excavation, remediation, and transportation. The application of the technique on a former smelting work site (lead pollution) demonstrates how the tool can be used. In this example, the forecasted volumetric uncertainty decreases rapidly for a relatively small number of samples (20-50) and then reaches a plateau (after 100 samples). The uncertainty related to the total remediation cost decreases while the expected total cost increases. Based on these forecasts, we show how a risk-prone decision maker would probably decide to take 50 additional samples while a risk-averse decision maker would take 100 samples.     

Rehabilitation of El Yahoudia dumping site, Tunisia

As in all developing countries, cities in Tunisia face serious problems of environmental pollution caused mainly by the inadequate and inefficient final disposal of their generated solid wastes. The Tunisian government launched a development program including the construction of landfills in the main cities and the closure of the contaminated sites issued from solid wastes landrising practice. The project of the Henchir El Yahoudia landfill restoration is the first experience in this programme. It has been suggested to convert the site to a green park and to implement an ornamental plant nursery. The whole surface of the landfill is approximately 100 ha from which 30 ha have been already transformed to an urban recreational area and the remaining 70 ha have to be characterized for the project extension. A field investigation by boring was conducted in order to define the geological and the hydrogeological conditions, the vertical and horizontal wastes layer extension, content and degree of decomposition and the composition and quantities of leachate and landfill gas. Representative samples of waste, soil, groundwater and leachate were collected for laboratory analyses. Several of these borings were converted to piezometers to define the flow regime in the site. The results showed that the biogas (CH4, H2S, and CO2), leachate and waste, distribution in the site is mainly affected by the temporal variation of the site operating method. The underlying fissured clay layer facilitated leachate infiltration into the groundwater where high BOD, COD and nitrogen concentrations were registered.     

Modeling Habitat Suitability for Complex Species Distributions by Environmental-Distance Geometric Mean

This paper presents a new habitat suitability modeling method whose main properties are as follows: (1) It is based on the density of observation points in the environmental space, which enables it to fit complex distributions (e.g. nongaussian, bimodal, asymmetrical, etc.). (2) This density is modeled by computing the geometric mean to all observation points, which we show to be a good trade-off between goodness of fit and prediction power. (3) It does not need any absence information, which is generally difficult to collect and of dubious reliability. (4) The environmental space is represented either by an expert-selection of standardized variables or the axes of a factor analysis [in this paper we used the Ecological Niche Factor Analysis (ENFA)].We first explain the details of the geometric mean algorithm and then we apply it to the bearded vulture (Gypaetus barbatus) habitat in the Swiss Alps. The results are compared to those obtained by the median algorithm and tested by jack-knife cross-validation. We also discuss other related algorithms (BIOCLIM, HABITAT, and DOMAIN). All these analyses were implemented into and performed with the ecology-oriented GIS software BIOMAPPER 2.0.The results show the geometric mean to perform better than the median algorithm, as it produces a tighter fit to the bimodal distribution of the bearded vulture in the environmental space. However, the median algorithm being quicker, it could be preferred when modeling more usual distribution.     

Regeneration of industrial district wastewater using a combination of Fenton process and ion exchange—A case study

Regeneration studies of wastewater effluent from an organized industrial district (OID) for possible reuse in textile industry as process water was investigated. Advanced treatment methods including Fenton process, polyaluminium chloride (PAC) coagulation and ion exchange were applied on OID effluent. In Fenton process removal efficiencies for suspended solids (SS), chemical oxygen demand (COD), SAC₄₃₆ (spectral absorption coefficient), SAC₅₂₅ and SAC₆₂₀ were determined 61%, 36%, 35%, 49% and 67%, respectively. After Fenton process, wastewater samples were coagulated with PAC. Optimum removal efficiencies for SS, COD, Fe ion, SAC₄₃₆, SAC₅₂₅ and SAC₆₂₀ were determined 83%, 18%, 93%, 32%, 36% and 58%, respectively. Ion exchange experiments were conducted on chemically coagulated wastewater samples to improve the quality of wastewater. Optimum dosage of resins was determined. The experiments revealed that 1:1 resin ratio (20 mL H-type resin:20 mL OH-type resin) gave the best removal rates for the parameters considered in this study. Study results indicated that quality of the wastewater was suitable for the process water characteristics of textile industry and unit wastewater treatment cost was determined as 2.54 €/m³.     

变电站复杂声场中多点噪声源的鉴别

复杂声场中单个声源的鉴别和评价是噪声污染控制的重要环节。简要介绍了几种常用的噪声源鉴别方法,然后结合变电站复杂声场中噪声产生的实际情况,针对变电站主要声源噪声的特性提出了两种方法的基本原理和具体操作步骤,即声强测量法和基于波叠加的噪声源识别方法,用以进行变电站中多点噪声源的鉴别。这为建立变电站声场中多点声源鉴别的标准方法提供了可能;对于厂界噪声超过环保部门确定标准的变电站,应用这些方法可以提供明确的治理思路。     

Influence of flooding and vegetation on carbon, nitrogen, and phosphorus dynamics in the pore water of a Spartina alterniflora salt marsh

Four sites were selected in a salt marsh in the Bah′?a Blanca Estuary (Argentina): (1) low marsh (flooded by the tide twice daily) vegetated by S. alterniflora; (2) non-vegetated low marsh; (3) high marsh (flooded only in spring tides) vegetated by S. alterniflora; (4) non-vegetated high marsh. The pH and Eh were measured in sediments, while dissolved nutrients (ammonium, nitrate, nitrite and phosphate) and particulate organic matter (POM) were determined in pore water. pH (6.2–8.7) was only a ected by vegetation in low areas. Eh (from –300 to 250 mV) was lower at low sites than at high ones; in the latter, the values were higher in the non-vegetated sediments. The POM concentration was greater in the high marsh than in the low marsh, with no e ect of vegetation. Ammonium was the most abundant nitrogen nutrient species in pore water, except in the non-vegetated high marsh where nitrate concentration was higher. All nitrogen nutrients were a ected by both flooding and vegetation. Phosphate was always present in pore water at all sites throughout the year and its concentration varied within narrow limits, with no e ect of flooding and greater values always at non-vegetated sites. Our results showed that the variability of the pore water composition within the marsh is greater than the temporal variation, meaning that both tidal flooding and vegetation are important in the dynamics of nutrients and organic matter in the sediment pore water.     

Sustainable fishing gear: the case of modified circle hooks in a Costa Rican longline fishery

Our research aims to identify longline fishing gear modifications that can improve fishing selectivity and reduce incidental capture of non-target species. Catch rates and anatomical hook locations (AHL) were compared when using a 14/0 standard ??control?? circle hook with a 0° offset and an experimental ??appendage?? hook in a Costa Rican longline fishery. With the appendage, the maximum dimension of the appendage hook was increased by 10% and the minimum dimension of the hook by 19%. A total of 1,811 marine animals were captured during five fishing trips. By taxonomic groups, sea turtles represented the largest total catch (27%), followed by sharks (26%), rays (25%), mahimahi (Coryphaena hippurus) (12%), and tunas and billfish (10%). Non-target and discard species, such as rays and sea turtles, accounted for over half of the total catch. Catch per unit effort (CPUE; number of individuals per 1,000 hooks) was higher with control hooks compared to appendage hooks for all species?? categories except rays; appendage hooks caught 52% fewer sea turtles and 23% fewer tunas and billfish than standard hooks, which represents a significant reduction in bycatch of endangered and other species. No differences were found in the AHL for sea turtles, suggesting use of the appendage may not incur additional advantages regarding turtles?? post-release survivorship. Despite lower catch rates for marketable species, such as sharks and mahimahi, use of the appendage resulted in dramatic reductions in catch rates of sea turtles. The results suggest that large scale adoption of hooks with a significantly wider hook dimension could be an effective conservation measure to maintain marine biodiversity while allowing for continued fishing.