Adoption Potential of Conservation Agriculture Practices in Sub-Saharan Africa: Results from Five Case Studies

Despite the reported benefits of conservation agriculture (CA), its wider up-scaling in Sub-Saharan Africa (SSA) has remained fairly limited. This paper shows how a newly developed qualitative expert assessment approach for CA adoption (QAToCA) was applied to determine its adoption potential in SSA. CA adoption potential is not a predictor of observed adoption rates. Instead, our aim was to systematically check relevant factors that may be influencing its adoption. QAToCA delivers an assessment of how suitable conditions “and thus the likelihood for CA adoption” are. Results show that the high CA adoption potentials exhibited by the Malawi and Zambia case relate mostly to positive institutional factors. On the other hand, the low adoption potential of the Zimbabwe case, in spite of observed higher estimates, is attributed mainly to unstable and less secured market conditions for CA. In the case of Southern Burkina Faso, the potential for CA adoption is determined to be high, and this assessment deviates from lower observed figures. This is attributed mainly to strong competition of CA and livestock for residues in this region. Lastly, the high adoption potential found in Northern Burkina Faso is explained mainly by the fact that farmers here have no alternative other than to adopt the locally adapted CA system—Zaï farming. Results of this assessment should help promoters of CA in the given regions to reflect on their activities and to eventually adjust or redesign them based on a more explicit understanding of where problems and opportunities are found.     

Past and future sustainability of water policies in Europe

The article contributes to a discussion on two global issues on water: water resources management, and water supply and sanitation. Focusing on Europe, it traces the legal roots of current systems in history: as a resource, water is considered as a common property, rather than a market good; while as a public service it is usually a commodity. Public water supply and sanitation technologies and engineering have developed under three main paradigms: quantitative and civil engineering; qualitative and chemical/sanitary engineering (both on the supply side); and the most recent one, environmental engineering and integrated management (on the demand side). The cost of public drinking water is due to rise sharply in view of the two‐fold financial challenge of replacing an ageing infrastructure and keeping up with ever‐rising environmental and sanitary quality standards. Who will pay? Government subsidies, or water users? The author suggests that apparent successes with privatisation may have relied heavily on hidden government subsidies and/or the healthy state of previously installed water infrastructure: past government subsidies are still felt for as long as the lifetime of the infrastructure. The article stresses the importance of public participation and decentralized local management of water and sanitation services. Informing and involving users in water management decisions is seen as an integral part of the ‘ethics’ side of the crucial three E's (economics, environment, ethics). The article strongly argues for municipal provision of water services, and hopes that lessons learnt and solutions found in the European experience may serve water services management efforts in other regions of the world.     

Effects of Riparian Vegetation and Watershed Urbanization on Fishes in Streams of the Mid‐Atlantic Piedmont (USA)1

Abstract: The joint influences of riparian vegetation and urbanization on fish assemblages were analyzed by depletion sampling in paired forested and nonforested reaches of 25 small streams along an urbanization gradient. Nonforested reaches were narrower than their forested counterparts, so densities based on surface area differ from linear densities (based on reach length). Linear densities (based on number or biomass of fish) of American eel, white sucker and tesselated darter, and the proportion of biomass of benthic invertivores were significantly higher in nonforested reaches, while linear densities of margined madtom and the number of pool species were significantly higher in forested reaches. Observed riparian effects may reflect differences in habitat and algal productivity between forested and nonforested reaches. These results suggest that relatively small‐scale riparian restoration projects can affect local geomorphology and the abundance of fish. Dense vegetative cover in riparian zones and similar or analogous habitats in both forested and nonforested reaches, the relatively small scale of the nonforested reaches, and the low statistical power to detect differences in abundance of rare species may have limited the observed differences between forested and nonforested reaches. There was a strong urbanization gradient, with reductions of intolerant species and increases of tolerant species and omnivores with increasing urbanization. Interactions between riparian vegetation type and urbanization were found for blacknose dace, creek chub, tesselated darter, and the proportion of biomass of lithophilic spawners. The study did not provide consistent support for the hypotheses that responses of fish to riparian vegetation would be overwhelmed by urban degradation or insignificant at low urbanization.     

Population monitoring for genetic damage induced by environmental physical and chemical agents

The short-term tests performed in vitro on different systems, from phage to human cells, or in vivo, on laboratory animals, allow only a qualitative estimate of the action of mutagenic agents, and the extrapolation of such experimental results to man may encounter many difficulties.Direct biomonitoring of populations exposed to chemicals could represent a more realistic approach for an evaluation of the hazards to man. Certain methods are still under development. Nevertheless, other ones can already by used routinely, e.g. the cytogenetic observations on peripheral blood lymphocytes and the Ames test for mutagenic substances in urine, and can provide useful suggestions how to set threshold limits for chemical substances encountered in the working environment.     

A Proactive Approach Can Make Site Remediation Less Expensive

Without any incentive to clean up a contaminated site, remediation is often delayed until the site owner is compelled to act by regulatory agencies. In such a context, the selected technology is typically the one that will reach the remediation goals as quickly as possible. Unfortunately, this criterion is often met by overly expensive technologies, resulting in high and sometimes unaffordable total remediation costs, leading to a remediation with a negative net benefit. This study examines the effects of time constraint and benefit value on the optimal remediation strategy for a diesel-contaminated site. This strategy is developed using the technico-economic model METEORS, which takes into account the technology’s effectiveness, the uncertainty of the level of contamination, and the possibility of reducing this uncertainty through either an additional characterization (before selecting and applying a technology) or the monitoring of the remediation technology (during its use). Results of simulations with both economic and temporal constraints support a proactive approach to site remediation.     

Lab-scale investigation of the ability of Polar Organic Chemical Integrative Sampler to catch short pesticide contamination peaks

Environmental Science and Pollution Research - In this lab-scale study, the POCIS capacity to integrate short contamination peaks of variable intensity and duration was evaluated. POCIS were...     

A comparative study of the effects of chloride, sulfate and nitrate ions on the rates of decomposition of H2O2 and organic compounds by Fe(II)/H2O2 and Fe(III)/H2O2

The effects of chloride, nitrate, perchlorate and sulfate ions on the rates of the decomposition of hydrogen peroxide and the oxidation of organic compounds by the Fenton's process have been investigated. Experiments were conducted in a batch reactor, in the dark at pH < or = 3.0 and at 25 degrees C. Data obtained from Fe(II)/H2O2 experiments with [Fe(II)]0/[H2O2]0 > or = 2 mol mol(-1), showed that the rates of reaction between Fe(II) and H2O2 followed the order SO4(2-) > ClO4(-) = NO3- = Cl-. For the Fe(III)/H2O2 process, identical rates were obtained in the presence of nitrate and perchlorate, whereas the presence of sulfate or chloride markedly decreased the rates of decomposition of H2O2 by Fe(III) and the rates of oxidation of atrazine ([atrazine]0 = 0.83 microM), 4-nitrophenol ([4-NP]0 = 1 mM) and acetic acid ([acetic acid]0 = 2 mM). These inhibitory effects have been attributed to a decrease of the rate of generation of hydroxyl radicals resulting from the formation of Fe(III) complexes and the formation of less reactive (SO4(*-)) or much less reactive (Cl2(*-)) inorganic radicals.     

Heavy metal bioaccumulation by the bryophyte Scleropodium purum at three French sites under various influences: rural conditions, traffic, and industry

An active biomonitoring of the heavy metals pollution experiment was undertaken by means of the bryophyte species Scleropodium purum transplanted at three different sites exposed to rural, traffic, or industrial influences. Concentrations of about 40 elements in S. purum were determined by instrumental neutron activation analysis and inductively coupled plasma mass spectrometry. Accumulation rates of heavy metals were determined in the three sites. These accumulation rates in polluted sites were matched together and also to those recorded at the rural site. The changes of the accumulation rate of heavy metals in S. purum versus their concentrations in PM₁₀ particles simultaneously collected above show some different accumulation properties of S. purum according to elements and sites. S. purum has a weak efficiency in the three sites to accumulate elements like V, Cr, Cu, Zn, As, Se, Sb, and Pb originating from atmospheric hot sources generally enriched in particulates matter (PM₁₀), whereas it is particularly high for Br, Th, and Rb. For other elements, Co, La, Ce, and Hf, and rare earth elements, Fe, Sr, Nb, Ti, Al, and Sc, the collection efficiency by S. purum is intermediate. In the industrial site Dunkerque, a magnification of the collection efficiency by S. purum for elements originating from steel and aluminum productions and petroleum refinement suggests that these metals could be enriched in coarse particles with a better accumulation by the bryophyte with respect to PM10.