Simulation of Exterior Conditions in Permanently Closed Soil Chambers by Controlling Air Flow,Soil Water Content,and Temperature

Volatile substances and gases resulting e.g. from degradation processes of chemicals in soils emit into the atmosphere and no chemical mass balance is complete without considering this path. Closed soil chambers allow the evaluation of this transfer to the atmosphere. This study deals with the influence of soil chambers with a glass plate cover on physical soil conditions in the chambers and the possibility to simulate the exterior conditions within the chambers. The water content immediately at the soil surface is an important factor for the microbial activity and the transfer of gaseous compounds to the atmosphere as well. It is monitored by specially designed water content sensors in 1 cm depth in the chamber and as control outside. Funnels with a cross section equal to the soil surface area of the chamber collect the rain water and channel it into the soil chamber. This results in soil water content in the chambers very similar to that outside. For the purpose of analysing ¹⁴CO₂ and volatile ¹⁴C-compounds, air is permanently pumped through the chamber. In order to simulate natural conditions, the wind speed is measured 1 cm above the soil surface outside the chambers. A control circuit adjusts the air flow through the chamber to a value corresponding to the wind speed outside. Temperature measurements in 1 cm depth verify that there is no significant difference between the soil chamber and the control outside.     

Floating aquatic macrophytes for the treatment of aquaculture effluents

Environmental Science and Pollution Research - Aquaculture is an activity with economic and social importance since it generates food, employment, and income. However, like other human activities,...     

Spatial planning and changing landscapes: a failure of policy in peri-urban Victoria,Australia

Building on the scientific literature, this article first summarises the socio-environmental impacts of land-use change expected to occur in high amenity Australian peri-urban areas, involving in particular, the effects of land development on agriculture, biodiversity, landscape character, bushfire risk and social factors. Second, the current spatial planning framework and its distribution in seven municipalities in Victoria, Australia, is critically analysed, and records of approved planning permits are related to this framework to assess the challenges posed by peri-urban growth. We argue that the current planning framework supports a static approach which does not address foreseen challenges and lacks strategic power. Both the strategic framework and the development approval process lead to unanticipated, cumulative impacts and contestation. A more coordinated, less urban-centric approach to planning and the introduction of rural land-use plans would substantially address some of the issues encountered.     

Ecological mechanisms linking protected areas to surrounding lands.

Land use is expanding and intensifying in the unprotected lands surrounding many of the world's protected areas. The influence of this land use change on ecological processes is poorly understood. The goal of this paper is to draw on ecological theory to provide a synthetic framework for understanding how land use change around protected areas may alter ecological processes and biodiversity within protected areas and to provide a basis for identifying scientifically based management alternatives. We first present a conceptual model of protected areas embedded within larger ecosystems that often include surrounding human land use. Drawing on case studies in this Invited Feature, we then explore a comprehensive set of ecological mechanisms by which land use on surrounding lands may influence ecological processes and biodiversity within reserves. These mechanisms involve changes in ecosystem size, with implications for minimum dynamic area, species-area effect, and trophic structure; altered flows of materials and disturbances into and out of reserves; effects on crucial habitats for seasonal and migration movements and population source/sink dynamics; and exposure to humans through hunting, poaching, exotics species, and disease. These ecological mechanisms provide a basis for assessing the vulnerability of protected areas to land use. They also suggest criteria for designing regional management to sustain protected areas in the context of surrounding human land use. These design criteria include maximizing the area of functional habitats, identifying and maintaining ecological process zones, maintaining key migration and source habitats, and managing human proximity and edge effects.     

Macrobenthic community colonization and community development in dredged material disposal habitats off coastal Louisiana

We examined marine benthic macroinvertebrate colonization and community structure at multiple spatial scales (study areas, reference and disposal sites, and depth zones within sites) within a 3-day period at three relatively widely separated (ca 60 km) dredged material disposal areas (Mermentau and Atchafalaya Rivers and Freshwater Bayou) in coastal Louisiana. Study areas had different histories of dredged material disposal, but all three are subject to frequent natural habitat disturbances (e.g. freshets). Nine phyla and 51 taxa were represented among the three study areas at reference (R) and disposal (D) sites (Freshwater Bayou: 21(R), 18 (D); Mermentau River: 14 (R), 17 (D) and Atchafalaya River: 38 (R), 40 (D)). Only 15 taxa were common to all three study areas. At the Freshwater Bayou, average taxa richness and abundance responded to water depth, not sites. These response variables averaged higher mean values at the Mermentau River disposal than at the reference site. No consistent pattern in the average of these response variables was detected between sites at the Atchafalaya River. Multidimensional scaling ordination and non-parametric multivariate inferential analysis provided a distinctly different picture of community structure within study areas compared to parametric analyses. A relatively moderate to strong separation in community structure between sites was detected depending on study area. Non-parametric multivariate inferential analysis detected significant differences in internal community structure at the scale of stations and sites within study areas. The weight of evidence suggests that frequent natural disturbances explain differences in macrobenthic animal community structure more than effects of dredged material disposal.     

Gas chromatography/mass spectrometry of paraquat UV-ozonation products

The chromatographic and mass spectral properties of 13 compounds isolated from the reaction of UV and ozone on paraquat are described. The products were extracted from the acidified reaction mixture and converted to TMS derivatives. The identified products were the diTMS ester of oxalic acid (m/z 234), the TMS ester of 4-picolinic acid (m/z 195), the diTMS ester of succinic acid (m/z 262), the diTMS derivative of N-formylglycine, 4,4'-bipyridyl (m/z 156), the triTMS derivative of malic acid (m/z 350), and the diTMS derivative of a hydroxy-4-picolinic acid. Structural features and tentative identification of some of the remaining compounds are discussed. The most prominent peak on the chromatogram has a probable molecular ion at m/z 219, isomeric to the diTMS derivative of glycine. The structures presented suggest that demethylation, ring oxidation and fragmentation of one or both rings of the bipyridinium di-cation occur during UV-ozonation of paraquat.