Headspace solid phase microextraction method for determination of triazine and organophosphorus pesticides in soil

A headspace solid phase microextraction method (HS-SPME) for simultaneous determination of five pesticides belonging to triazine and organophosphorus pesticide groups in soil samples was developed. Microextraction conditions, such as temperature, extraction time and sodium chloride (NaCl) content were investigated and optimized using 100 μ m polydimethyl-siloxane (PDMS) fiber. Detection and quantification were done by gas chromatography-mass spectrometry (GC-MS). Relative standard deviation (RSD) and recovery values for multiple analysis of soil samples fortified at 30 μ g kg^{? 1} of each pesticide were below 13 % and higher than 70 %, respectively. Limits of detection (LOD) for all the compounds studied were less than 3.2 μ g kg^{? 1}. The proposed method was applied in the analysis of some agricultural soil samples.     

The role of bio-mechanical treatments of waste in the dioxin emission inventories

PCDD/Fs are one of the most studied molecules in the world because of their toxicity. In the last years the toxicity of these compounds has been analyzed in details. For years PCDD/F inventories have pointed out the significant role of municipal solid waste (MSW) incinerators in the overall balance. Recently, thanks to new regulations on PCDD/F emissions, in a few countries this scenario is changing: it can be demonstrated that modern MSW incinerators can play a secondary role even if the percentage of MSW sent to combustion has increased. In the latest inventories an unconventional source of PCDD/F has appeared: in nineties some biogas characterizations have demonstrated that there is a release of PCDD/F from MSW sanitary landfills. In addition, the combustion of collected biogas can generate not negligible amounts of PCDD/F. A new question can be put: does the MSW contribute with other management options to the overall balance of PCDD/F? The present work points out that a detailed inventory should take into account also the PCDD/F release from bio-mechanical treatment plants (both composting and bio-drying/bio-stabilization plants). However the contribution from this option is secondary when it is compared with the one from old MSW incinerators.     

Large-scale shrimp farming in coastal wetlands of Venezuela,South America: Causes and consequences of land-use conflicts

In Venezuela, large-scale shrimp farming began in the 1980s. By 1987, the Ministry of Environment and Natural Resources (MARNR) had received 14 proposals for approval. A developer illegally started the construction of ponds at the Píritu Lagoon in the State of Anzoátegui before the authorization process was completed. This action triggered a land-use conflict. This study identifies the causes for public protest and determines the consequences of this conflict for land-use management. The results show that public protest was based on the impacts of the partial construction of ponds. These impacts were related to direct removal of wetlands, interruption of natural patterns of surface flows, and alteration of feeding grounds of some bird species with migratory status. Consequences were identified in relation to the role that nongovernmental organizations (NGOs) play in land-use conflicts and the actions that MARNR could take in the future to prevent and solve similar situations.     

Effects of soil composition on solid phase microextraction determination of triazine and organophosphorus pesticides

The influence of organic matter and clay contents on headspace solid phase microextraction (HS-SPME) determination of triazine and organophosphorus pesticides in different soils was studied. The results of the study showed that content of soil organic matter dominantly participated in sorption of triazines (simazine, atrazine and prometryn) to soil, while sorption of organophosphorus pesticides (phorate and tebupirimfos) could not be explained only by contents of dominant soil sorption components (soil organic matter and clay). Sorption of all pesticides studied to different soil types was similar at their lower concentrations while the influence of soil composition was expressed at higher concentration levels. Except for phorate, the obtained sorption trends were different from those obtained by direct SPME mode (DM-SPME) and exhaustive liquid-solid extraction (LSE) method. These results indicated that most likely co-extractants from the analyzed medium complicated evaporation and diffusion of the pesticides to the PDMS fiber during HS-SPME sampling.     

A proposal for a diet-based local PCDD/F deposition limit

This study proposes a method to estimate the maximal tolerable value for the atmospheric deposition of dioxins (PCDD/Fs) to soil. The case study for the application of this methodology is an Alpine valley where a steel production plant is present. In order to estimate the limit value for the PCDD/F deposition, consolidated food chain models were applied, but were adapted to be run backwards with respect to their original formulation, by starting from the diet of people living in the region and from the PCDD/F Tolerable Daily Intake value proposed by the World Health Organization. For this case study, the estimated limit value was 2.30 pg WHO-TEQ m⁻² d⁻¹ when only local diary products were taken into account and 1.91 pg WHO-TEQ m⁻² d⁻¹ when also the role of local cereals and vegetables was considered. The average PCDD/F deposition measured in the same region during a monitoring campaign was lower than the above limit values (1.40 pg WHO-TEQ m⁻² d⁻¹). Indications on how to consider the contribution of meat and fish are provided too. The approach proposed in this paper represents a useful tool to assess the acceptable overall deposition for a specific region.     

Contrasting approved uses against actual uses at La Restinga Lagoon National Park, Margarita Island, Venezuela. A GPS and GIS method to improve management plans and rangers coverage

Protected areas are the core of efforts to conserve biological diversity and zoning uses, and they are used as a tool for their management. Global Positioning Systems (GPS) and Geographic Information System (GIS) have been used to evaluate conflicts between approved uses and actual uses in La Restinga Lagoon National Park in Venezuela (LRLNP). The park (188.6 km²), covers various ecosystems such as coastal lagoons, marine waters and xerophytic vegetation, it is visited by up to 260,000 people visit per year. A GIS, using a base map compiled from 1:25,000 maps was developed. Natural cover was mapped from LANDSAT VII TM images, orthophotomaps and aerial photographs. Spatial use data was collected by field GPS location of any use inside the park during 2 years. Thematic vector maps for each land cover, zoning area, and observed use were created. Maps of zoning and uses were overlapped and new maps for each use-zoning crossing were created. The park contain nine different zoning areas wherein 28 different uses were identified, 18 of them were direct consumptive and non-consumptive uses, occurring on 54% of the park. Tourism transit areas were the most used zones. More than 5,000 people use the park during a high season day. Superimposition of zoning maps with actual use data produced 13 uses taking place in not allowed areas (46% of park area). Most common prohibited use was commercial net fishing, occurring in nearly 40% of the park area. Therefore, identifying human use conflicts and its geographical distribution is a key issue to improve Management Plans as well as identifying hot sites. The GPS-GIS methodology presented here allows Park Rangers to select those areas which could benefit from enhanced supervision with the limited budget available.