Impact of sewage sludge spreading on nickel mobility in a calcareous soil: adsorption–desorption through column experiments

A soil column adsorption–desorption study was performed on an agricultural calcareous soil to determine the impact of sewage sludge spreading on nickel mobility. Ni adsorption experiments were followed by desorption tests involving the following liquid extractants: water, calcium (100 mg/L), oxalic acid (525 mg/L equivalent to 100 mg carbon/L), and sludge extracts (0.5 and 2.5 g/L). Desorption tests were also conducted after sewage sludge spreading at three application rates (30, 75, and 150 t/ha). According to the breakthrough curve, Ni adsorption was irreversible and occurred mainly through interactions with calcite surface sites. Nickel desorption from the soil column was promoted in presence of significant dissolved organic carbon (DOC) concentration as observed with oxalic acid elution and sludge extract at 2.5 g/L. In sludge-amended soil columns, the maximum Ni levels occurred in first pore volumes, and they were positively correlated to the sludge application rate. The presence of DOC in leaching waters was the main factor controlling Ni desorption from the sludge-amended soil columns. This finding implies that DOC generated by sludge applied on calcareous soils might facilitate the leaching of Ni due to the formation of soluble Ni–organic complexes. Thus, sludge application can have potential environmental impacts in calcareous soils, since it promotes nickel transport by decreasing Ni retention by soil components.     

Non-timber forest products farming and empowerment of rural women in Ghana

United Nations estimates indicate that up to 70% of the world’s poor are female, and women in developing countries constitute the majority of the labour force, playing a key role in managing community resources and helping to improve food security and protect the environment. Increased attention in recent years has been focused on the potential role of non-timber forest products (NTFPs) in improving the incomes and health of women in developing countries. NTFPs farming and marketing are very critical for the economic empowerment of rural poor, particularly women. Despite this potential, the contribution of NTFPs farming to the empowerment of women remains largely undervalued and understudied. This paper examines the potential contribution of NTFPs farming in poverty reduction and livelihood improvement of women in Ghana using the Sefwi Wiawso District (SWD) and Bibiani-Bekwai District (BBD) in the Western Region of Ghana as a case study. The paper explores the contribution of NTFPs farming to the total annual income, acquisition of assets, health, and food security of women through participatory research methods. ANOVA and Pearson Correlation (p < 0.05) show that a significant association exists between total annual income of women, acquisition of assets, health, food security, and the income earned from NTFPs in the SWD and BBD. The study revealed that NTFPs can contribute significantly to the economic empowerment of women. The paper asserts that commercialisation of NTFPs will have a greater impact on women’s livelihoods and therefore any opportunity for increasing their involvement is very essential for the empowerment and sustainable development of rural communities in Ghana.     

Plant biodiversity and ethnobotany inside the projected impact area of the Upper Seti Hydropower Project,Western Nepal

A survey of plant biodiversity and ethnobotany was conducted along the Seti river banks in the Tanahun district of Western Nepal. This area, home of the Magar ethnic group, will be impacted by a major hydropower project, currently under feasibility study. The objective of the study was to document plant biodiversity and ethnobotany in order to suggest appropriate conservation and management strategies. Botanical sampling was conducted inside quadrats and along transects. A total of 221 plant species were recorded in the study area, distributed as herbs (80 species), trees (68), shrubs (28), climbers (19), pteridophytes (18), lianas (5), and epiphytes (3). Twelve of the inventoried species figure in one or more conservation categories identified by various national or international agencies. Group discussions and personal interviews allowed to find out that 43% of the species were ethnobotanically important for the local people and that most were used as medicine, food, or timber. We propose specific species for sustainable use programs based on certain criteria. The area is very important in terms of plant biodiversity and ethnobotany, and hence, immediate implementation of conservation measures is recommended to maintain the high social, ecological and economic values of the area.     

Assessment of nitrate pollution in the Grand Morin aquifers (France): combined use of geostatistics and physically based modeling

The objective of this work is to combine several approaches to better understand nitrate fate in the Grand Morin aquifers (2700 km(2)), part of the Seine basin. cawaqs results from the coupling of the hydrogeological model newsam with the hydrodynamic and biogeochemical model of river ProSe. cawaqs is coupled with the agronomic model Stics in order to simulate nitrate migration in basins. First, kriging provides a satisfactory representation of aquifer nitrate contamination from local observations, to set initial conditions for the physically based model. Then associated confidence intervals, derived from data using geostatistics, are used to validate cawaqs results. Results and evaluation obtained from the combination of these approaches are given (period 1977-1988). Then cawaqs is used to simulate nitrate fate for a 20-year period (1977-1996). The mean nitrate concentrations increase in aquifers is 0.09 mgN L(-1)yr(-1), resulting from an average infiltration flux of 3500 kgN.km(-2)yr(-1).     

Effect of liquefied petroleum gas on ozone formation in Guadalajara and Mexico City

Leakages of liquefied petroleum gas (LPG) are suspected to contribute greatly to ozone (O3) formation in Mexico City. We tested such a hypothesis by outdoor captive-air irradiation (CAI) experiments in the two largest Mexican metropolitan areas: Guadalajara (GMA) in 1997 and Mexico City (MCMA) in 2000. O3 was monitored in each city for 20 days (8:00 a.m.-6:00 p.m.) in smog chambers containing unaltered morning air or morning air enriched with either commercial LPG or LPG synthetic mixture 60/40 (propane and butane). Tested additions of both components were 35% (by volume) in GMA and 60% (by volume) in MCMA. The addition effects on O3 (max) were compared with effects from diluting LPG components or total nonmethane hydrocarbons (tNMHCs) by 50%. Diluting tNMHCs had the greatest absolute effect at both cities: it lowered O3 (max) by 24% in GMA and 55% in MCMA. Adding commercial LPG increased O3 (max) by 6% in GMA and 28% in MCMA; whereas adding LPG synthetic mixture 60/40 caused a similar increase in O3 (max), 4 and 21% in GMA and MCMA, respectively. Compared with dilution of tNMHCs, dilution of LPG-associated compounds had a smaller decreasing effect on O3 (max), only 4% in GMA and 15% in MCMA. These results show that commercial LPG and LPG synthetic mixture 60/40 affect O3 formation to a lesser extent than estimated previously.     

Small but smart: the interaction between environmental cues and internal state modulates host-patch exploitation in a parasitic wasp

The reproductive success of insect parasitoids depends on two activities, searching for hosts to obtain immediate fitness rewards (offspring) and searching for food to extend life span and enhance future reproductive opportunities. Models suggest that to deal with this trade-off and to cope with the variability of the resources they depend on, parasitoids should simultaneously integrate information originating from three distinct sources: host and food availabilities in the environment (environmental information) and the metabolic reserves of the parasitoid (internal information). We tested whether, in the parasitic wasp Venturia canescens, these three types of information are perceived simultaneously and interact during host-patch exploitation. Experiments were performed with strains originating from two different geographical locations and with individuals of the two reproductive modes, arrhenotoky and thelytoky. We hypothesised that there would be differences between modes of reproduction as they thrive in different ecological conditions. Our results show that metabolic state, food availability and the number of ovipositions performed simultaneously modulate patch residence time in V. canescens of both populations and reproductive modes. Unfed wasps left their host patch earlier than fed ones. The tendency to leave the patch increased with an increasing probability of finding food. Our study confirms that globally, each oviposition increases the patch-leaving tendency (decremental mechanism). This effect was modulated by both the metabolic reserves and food availability, and the relationship depended on the geographic origin of populations. Individuals of one of the populations switched from a decremental to an incremental patch-leaving mechanism depending on the presence or absence of food in the vicinity. Differences between reproductive modes in the responses to environmental cues can be explained by the different ecological conditions they live in.     

Water to atmosphere fluxes of 131I in relation with alkyl-iodide compounds from the Seine Estuary (France)

This study presents an original work on measurements of stable and radioactive iodinated species in the Seine estuary (France), with estimates fluxes of volatile gaseous species from water to the atmosphere. Various iodinated compounds were identified in water and air in particular 131I in water, what is unusual. Concentrations and behaviour of iodinated elements in the Seine estuary seem similar to what has been observed in other European estuaries. MeI (Methyl Iodide) and Total Volatile Iodine (TVI) fluxes from water to air vary between 392 and 13949 pmol m(-2) d(-1) and between 1279 and 16484 pmol m(-2) d(-1), respectively. Water to air flux of TVI for the Seine river was estimated in the range 4-46 kg y(-1). Measurements of (131)I in water varying between 0.4 and 11.9 Bq m(-3). Fluxes of (131)I from water to atmosphere are in the range 2.4 x 10(5)-1.3 x 10(7)Bq y(-1), close to an annual discharge of (131)I by a nuclear reactor.     

Effect of metallic cations on the sorption of pesticides on soil

We studied the adsorption and desorption of two pesticides, namely isoproturon and dimetomorph, onto a model soil sample. We first show that the adsorption of isoproturon depends on pH, from 1 mg g⁻¹ at pH 4 to 2 mg g⁻¹ at pH 10, contrary to the adsorption of dimetomorph (5.8 mg g⁻¹). We also studied the influence of metallic cations, copper(II), iron(III), manganese(II), and chromium(III), on the sorption of isoproturon and dimetomorph. We found that in the case of isoproturon, the presence of metallic cations does influence the retention capacity of the soil sample. The sorption becomes very weak in the presence of copper and chromium, whereas in the case of iron and manganese the sorption properties are slightly modified.