Radiation modeling of a photo-reactor using a backward ray-tracing method: an insight into indoor photocatalytic oxidation

This article aims to understand the radiation behavior within a photo-reactor, following the ISO 22197-1:2007 standard. The RADIANCE lighting simulation tool, based on the backward ray-tracing modeling method, is employed for a numerical computation of the radiation field. The reflection of the glass cover in the photo-reactor and the test sample influence the amount of irradiance received by the test-sample surface in the photo-reactor setup. The reflection of a white sample limits the irradiance reduction by the glass cover to 1.4 %, but darker samples can lead to an overestimation up to 9.8 % when used in the same setup. This overestimation could introduce considerable error into the interpretation of experiments. Furthermore, this method demonstrates that the kinetics for indoor photocatalytic pollutant degradation can be refined through radiation modeling of the reactor setup. In addition, RADIANCE may aid in future modeling of the more complex indoor environment where radiation affects significantly photocatalytic activity.     

A review of plant–pharmaceutical interactions: from uptake and effects in crop plants to phytoremediation in constructed wetlands

Pharmaceuticals are commonly found both in the aquatic and the agricultural environments as a consequence of the human activities and associated discharge of wastewater effluents to the environment. The utilization of treated effluent for crop irrigation, along with land application of manure and biosolids, accelerates the introduction of these compounds into arable lands and crops. Despite the low concentrations of pharmaceuticals usually found, the continuous introduction into the environment from different pathways makes them ‘pseudo-persistent’. Several reviews have been published regarding the potential impact of veterinary and human pharmaceuticals on arable land. However, plant uptake as well as phytotoxicity data are scarcely studied. Simultaneously, phytoremediation as a tool for pharmaceutical removal from soils, sediments and water is starting to be researched, with promising results. This review gives an in-depth overview of the phytotoxicity of pharmaceuticals, their uptake and their removal by plants. The aim of the current work was to map the present knowledge concerning pharmaceutical interactions with plants in terms of uptake and the use of plant-based systems for phytoremediation purposes.     

Habitat segregation mediates predation by the benthic fish <Emphasis Type="Italic">Cottus gobio</Emphasis> on the exotic amphipod species <Emphasis Type="Italic">Gammarus roeseli</Emphasis>

Predation is often considered as one of the most important biotic factor determining the success of exotic species. The freshwater amphipod Gammarus roeseli has widely colonized Western Europe, where it is frequently found in sympatry with the native species (Gammarus pulex). Previous laboratory experiments revealed that G. roeseli may have an advantage over G. pulex through differential predation by native fish (brown trout). Morphological anti-predator defences (spines) were found responsible for lower rates of predation on the invasive G. roeseli. Here, using both field surveys and laboratory experiments, we tested if a differential of predation exists with other fish predators naturally encountered by gammarids. The main predators present in our field site were nocturnal benthic feeders (mainly bullheads, Cottus gobio). Fish diet analysis showed that, compared to its global availability in the river, G. roeseli was less consumed than G. pulex. In the field, however, G. roeseli was found mainly in the aquatic vegetation whereas G. pulex was found in all habitat types. Laboratory experiments in microcosms revealed that G. roeseli was less prone to predation by C. gobio only when vegetation was present. Depending on the type of predator, the differential of predation could therefore be mediated by antipredator behaviour, and a better usage of refuges, rather than by morphological defences.     

Nest site selection and induced response in a dominant arboreal ant species

It is well known that arboreal ants, both territorially dominant species and plant ants (e.g., species associated with myrmecophytes or plants housing them in hollow structures), protect their host trees from defoliators. Nevertheless, the presence of an induced defense, suggested by the fact that the workers discovering a leaf wound recruit nestmates, is only known for plant ants. Based on the results from a field study, we show here (1) that colonies of Azteca chartifex, a territorially dominant, neotropical arboreal ant species, mostly selected Goupia glabra (Goupiaceae) trees in which to build their principal carton nests and (2) that plant signals induced workers to recruit nestmates, which patrol the leaves, likely providing the plant with a biotic defense. Furthermore, the number of recruited workers was clearly higher on G. glabra, their most frequently selected host tree species, than on other tree species. These results show that contrary to what was previously believed, induced responses are also found in territorially dominant arboreal ants and so are not limited to the specific associations between myrmecophytes and plant ants.     

Arsenic speciation for the phytoremediation by the Chinese brake fern, Pteris vittata

Arsenic (As) speciation for the phytoremediation by the Chinese brake fern was studied. In particular, the mechanism of how plants induce compounds containing thiol (SH) and proteins by As exposure in terms of the relationship between As and phosphate uptaken into plant cells was examined. Pteris vittata callus could efficiently reduce As(V) to As(III) by the rapid introduction of reductase and synthesize thiols leading to phytochelatins production. Furthermore, Pteris vittata could control phosphate concentration in the cells corresponding to the concentration of arsenite and arsenate. To our best knowledge, this is the first report to show the mechanisms of such high As tolerance of Pteris vittata using their callus in terms of in vitro approach for the analysis of As speciation and metabolism route.     

Field-breeding birds on organic and conventional arable farms in the Netherlands

In this study territory densities of field-breeding farmland birds were compared on pairwise-selected organic and conventional arable farms for two years. Differences in territory densities between the two farm types were explained examining the effects of three factors on territory densities: (1) non-crop habitats, (2) crop types and (3) within-crop factors. In both years, densities of most species did not differ between organic and conventional farms. Only skylark and lapwing were more abundant on organic farms, but only skylarks showed a consistent pattern over both years. Differences in crop types grown between the two systems were the only explaining factor for differences in densities of skylark. For lapwing, the difference was only partly due to differences in crop type, but differences in within-crop factors (probably as a result of crop management) were likely to have had an effect as well. There were no significant differences in abundance of non-crop habitats between the two farming systems, so this could not explain differences in territory densities.     

Socioeconomic potential of carbon sequestration through agroforestry in the West African Sahel

The recognition of agroforestry as a greenhouse-gas mitigation strategy under the Kyoto Protocol to the United Nations Framework Convention on Climate Change (UNFCCC) offers an opportunity to agroforestry practitioners to benefit from the global Carbon (C) credit market. Our knowledge on this important topic from the semiarid regions such as the West African Sahel (WAS) is, however, very limited. In order to fill this gap, this study was undertaken in the Ségou region of Mali (annual temperature, 29°C; annual rainfall, 300–700 mm in 60 to 90 days), focusing on two improved agroforestry systems (live fence and fodder bank) along with traditional parkland agroforestry systems of the region. A cost–benefit analysis was conducted to assess the economic profitability and risks associated with the systems considering them as 25-year projects and their potential for participation in C credit market. The traditional systems had high C stock in their biomass and soil, but little potential for sequestering additional C; on the other hand, the improved systems had low C stock, but high sequestration potential. For the standard size live fence (291 m) and fodder bank (0.25 ha) projects, the estimated net present values (NPV) were $ 96.0 and $158.8 without C credit sale, and $109.9 and $179.3 with C sale, respectively. From the C sale perspective, live fence seemed less risky and more profitable than fodder bank. Carbon credit sale is likely to contribute to economic development of the subsistence farmers in the WAS.

Runoff and sediment losses from 27 upland catchments in Southeast Asia: Impact of rapid land use changes and conservation practices

Rapid changes in upland farming systems in Southeast Asia generated predominantly by increased population pressure and ‘market forces’ have resulted in widespread land degradation that has been well documented at the plot scale. Yet, the links between agricultural activities in the uplands and downstream off-site effects remain largely unknown because of the difficulties in transferring results from plots to a larger scale. Many authors have thus pointed out the need for long-term catchment studies. The objective of this paper is to summarize the results obtained by the Management of Soil Erosion Consortium (MSEC) over the last 5 years from 27 catchments in five countries (Indonesia, Laos, Philippines, Thailand, and Vietnam). The purpose of the study was to assess the impacts of cultivation practices on annual runoff and erosion rates. Initial surveys in each catchment included topography, soils and land use. Monitoring included climatic, hydrologic and erosion (total sediment yield including bed load and suspended sediment load) data, land use and crop yields, and farmers’ income. In addition, new land management options were introduced through consultations with farmers and evaluated in terms of runoff and erosion. These included tree plantations, fruit trees, improved fallow with legumes, maize intercropped with legumes, planted fodder, native grass strips and agro-ecological practices (direct sowing and mulch-based conservation agriculture). Regressions analyses showed that runoff during the rainy season, and normalized runoff flow coefficient based on erosive rainfall during the rainy season (rainfall with intensity exceeding 25 mm h⁻¹) increase with the percentage of the catchment covered by maize. Both variables decrease with increasing soil depth, standard deviation of catchment slope (that reflects terrain roughness), and the percentages of the catchment covered by fallow (regular and improved), tree plantations and planted fodder. The best predictors of sediment yield were the surface percentages of maize, Job's tears, cassava and footpaths. The main conclusions generated from this study were: (i) soil erosion is predominantly influenced by land use rather than environmental characteristics not only at the plot scale but also at the catchment scale; (ii) slash-and-burn shifting cultivation with sufficiently long rotations (1 year of cultivation, 8 years of fallow) is too often unjustly blamed for degradation; (iii) in its place, continuous cropping of maize and cassava promotes high rates of soil erosion at the catchment scale; (iv) conservation technologies are efficient in reducing runoff and total sediment yield at the catchment scale; (v) the adoption of improved soil management technologies by upland farmers is not a function of the degree of intensification of their farming system and/or of their incomes. The results suggest that if expansion of maize and cassava into already degraded upland systems were to occur due to increased demand for biofuels, there is a risk of higher runoff and sediment generation. A failure to adopt appropriate land use management strategies will result in further rapid resource degradation with negative impacts to downstream communities.     

Forestry Mitigation Options for Mexico: Finding Synergies between National Sustainable Development Priorities and Global Concerns

We examine carbon (C) reference and mitigation scenarios for the Mexicanforest sector between the year 2000 and 2030. Estimates are presentedseparately for the period 2008–2012.Future C emissions and capture are estimated using a simulation modelthat: a) allocates the country land use/land cover classes among differentfuture uses and categories using demand-based scenarios for forestryproducts; b) estimates the total C densities associated to each land usecategory, and c) determines the net carbon implications of the process ofland use/cover change according to the different scenarios.The options analyzed include both afforestation/reforestation, such ascommercial, bionenergy and restoration plantations, and agroforestrysystems, and forest conservation, through the sustainable management ofnative forests and forest protection.The total mitigation potential, estimated as the difference between the totallong-term carbon stock in the reference and the mitigation scenario reaches300 × 10⁶ Mg C in the year 2012 and increases to 1,382 × 10⁶ Mg C in 2030. The average net sequestration in the 30 year period is 46 × 10⁶ Mg C yr^-1, or 12.5 × 10⁶ Mg C yr^-1 within the period 2008 to 2012. The costs of selected mitigation options range from 0.7–3.5 Mg C^-1 to 35 Mg C^-1. Some options are cost effective.     

Carbon mitigation potential and costs of forestry options in Brazil,China, India,Indonesia, Mexico,the Philippines and Tanzania

This paper summarizes studies of carbon (C) mitigation potential and costs of about 40 forestry options in seven developing countries. Each study uses the same methodological approach – Comprehensive Mitigation Assessment Process (COMAP) – to estimate the above parameters between 2000 and 2030. The approach requires the projection of baseline and mitigation land-use scenarios. Coupled with data on a per ha basis on C sequestration or avoidance, and costs and benefits, it allows the estimation of monetary benefit per Mg C, and the total costs and carbon potential. The results show that about half (3.0 Pg C) the cumulative mitigation potential of 6.2 Petagram (Pg) C between 2000 and 2030 in the seven countries (about 200× 10⁶ Mg C yr^-1) could be achieved at a negative cost and the remainder at costs ranging up to $100 Mg C^-1. About 5 Pg C could be achieved, at a cost less than $20 per Mg C. Negative cost potential indicates that non-carbon revenue is sufficient to offset direct costs of these options. The achievable potential is likely to be smaller, however, due to market, institutional, and sociocultural barriers that can delay or prevent the implementation of the analyzed options.