Leaching of cyanogenic glucosides and cyanide from white clover green manure

Use of crops for green manure as a substitute for chemical fertilizers and pesticides is an important approach towards more sustainable agricultural practices. Green manure from white clover is rich in nitrogen but white clover also produces the cyanogenic glucosides (CGs) linamarin and lotaustralin; CGs release toxic hydrogen cyanide (HCN) upon hydrolysis which may be utilized for pest control. We demonstrate that applying CGs in the form of a liquid extract of white clover to large columns of intact agricultural soils can result in leaching of toxic cyanide species to a depth of at least 1m. Although degradation of the CGs during leaching proceeded with half lives in the interval 1.5-35 h depending on soil characteristics, a fraction of the applied CGs (0.9-3.2%) was recovered in the leachate as either CGs or toxic cyanide species. Detoxification of the HCN formed was rapid in soil and leachate from both sandy and loamy soil. However, 30% of the leachate samples exceeded the EU threshold value of 50 micrgl(-1) total cyanide for drinking water and 85% exceeded the US threshold of 5 micrgl(-1) for cyanide chronic ecotoxicity in fresh water. This study demonstrates that even easily degradable natural products present in crop plants as defense compounds pose a threat to the quality of groundwater and surface waters. This aspect needs consideration in assessment of the risk associated with use of crops as green manure to replace chemical fertilizers and pesticides as well as in genetic engineering approaches to design crops with improved pest resistance.     

Age before beauty? Relationships between fertilization success and age-dependent ornaments in barn swallows

When males become more ornamented and reproduce more successfully as they grow older, phenotypic correlations between ornament exaggeration and reproductive success can be confounded with age effects in cross-sectional studies, and thus say relatively little about sexual selection on these traits. This is exemplified here in a correlative study of male fertilization success in a large colony of American barn swallows (Hirundo rustica erythrogaster). Previous studies of this species have indicated that two sexually dimorphic traits, tail length and ventral plumage coloration, are positively correlated with male fertilization success, and a mechanism of sexual selection by female choice has been invoked. However, these studies did not control for potential age-related variation in trait expression. Here, we show that male fertilization success was positively correlated with male tail length but not with plumage coloration. We also show that 1-year-old males had shorter tails and lower fertilization success than older males. This age effect accounted for much of the covariance between tail length and fertilization success. Still, there was a positive relationship between tail length and fertilization success among older males. But as this group consisted of males from different age classes, an age effect may be hidden in this relationship as well. Our data also revealed a longitudinal increase in both tail length and fertilization success for individual males. We argue that age-dependent ornament expression and reproductive performance in males complicate inferences about female preferences and sexual selection.     

Cost comparison between private and public collection of residual household waste: Multiple case studies in the Flemish region of Belgium

The rising pressure in terms of cost efficiency on public services pushes governments to transfer part of those services to the private sector. A trend towards more privatizing can be noticed in the collection of municipal household waste. This paper reports the findings of a research project aiming to compare the cost between the service of private and public collection of residual household waste. Multiple case studies of municipalities about the Flemish region of Belgium were conducted. Data concerning the year 2009 were gathered through in-depth interviews in 2010. In total 12 municipalities were investigated, divided into three mutual comparable pairs with a weekly and three mutual comparable pairs with a fortnightly residual waste collection. The results give a rough indication that in all cases the cost of private service is lower than public service in the collection of household waste. Albeit that there is an interest in establishing whether there are differences in the costs and service levels between public and private waste collection services, there are clear difficulties in establishing comparisons that can be made without having to rely on a large number of assumptions and corrections. However, given the cost difference, it remains the responsibility of the municipalities to decide upon the service they offer their citizens, regardless the cost efficiency: public or private.     

Will Consumers Save The World? The Framing of Political Consumerism

An active ethically conscious consumer has been acclaimed as the new hero and hope for an ethically improved capitalism. Through consumers’ “voting” at the checkout, corporations are supposed to be held accountable for their conduct. In the literature on political consumerism, this has mainly been approached as political participation and governance. In this article, we do a critical review of this literature. We do so by questioning the existence of what we call a “generic active consumer model.” At the core of this position, there is a belief that the active consumer is a universal entity, available across nations and time. Instead we call for an approach that takes accord of the ways consumers and consumer roles are framed in interactive processes in markets, governance structures, and everyday life. Consumers in different countries assess their responsibilities and their powers as consumers differently due to different institutionalizations within distinctive contexts. We also must take into account how the inertia of ordinary consumption and the moral complexities of everyday life restrict the adoption of an active consumerist role. Hence, the debate on political consumerism should make for a more realistic notion of ethical consumer-sovereignty and its role in improving the workings of capitalism. In our view, these findings have severe implications for understanding both theories of political consumption and the dynamics of political consumption per se.     

Variation of MCPA, metribuzine, methyltriazine-amine and glyphosate degradation, sorption, mineralization and leaching in different soil horizons

Pesticide mineralization and sorption were determined in 75 soil samples from 15 individually drilled holes through the vadose zone along a 28 km long transect of the Danish outwash plain. Mineralization of the phenoxyacetic acid herbicide MCPA was high both in topsoils and in most subsoils, while metribuzine and methyltriazine-amine was always low. Organic matter and soil pH was shown to be responsible for sorption of MCPA and metribuzine in the topsoils. The sorption of methyltriazine-amine in topsoil was positively correlated with clay and negatively correlated with the pH of the soil. Sorption of glyphosate was tested also high in the subsoils. One-dimensional MACRO modeling of the concentration of MCPA, metribuzine and methyltriazine-amine at 2 m depth calculated that the average concentration of MCPA and methyltriazine-amine in the groundwater was below the administrative limit of 0.1 μg/l in all tested profiles while metribuzine always exceeded the 0.1 μg/l threshold value.     

环境中的药物——LC-MS/MS分析地表水和地下水

成百上千的活性物质正被用于人药和兽药处方中.由于药物的广泛应用,它们的残留物可通过多种途径进入环境.虽然主要通过尿和粪便的排泄,但是药品生产中的排放也应被考虑.当抗生素用于水产业,就会产生更直接的影响.污水处理设备不能完全除去药物,因此药物会出现在地表和地下水样品中.近年来,人们对环境中药物的兴趣正在增加,需要建立一种快速、灵敏、有选择性的方法来分析水样.     

Beach erosion and geochemical factors: Influence on spawning success of horseshoe crabs (Limulus polyphemus) in Delaware Bay

Horseshoe crab spawning activity is spatially patchy within the Delaware Estuary. This study investigated the importance of geochemical and erosional factors to the selection of breeding beaches. Two sandy beaches in Cape May county, New Jersey, USA, were studied; one beach had been subjected to considerable erosion, exposing underlying peat; the second beach, less than 1 km away, had only traces of peat. Reduced sediments with high levels of hydrogen sulfide were correlated with the presence of peat, and significantly fewer crabs utilized sediments in the proximity of peat beds for reproduction. The lower spawning activity on the beach in the vicinity of exposed peat, suggests that crabs may detect, at a distance, the nature of sediments and the quality of beach for spawning activity. Active salt marsh and peat-bank sediments dominate the upper bay shore; these sediments are unsuitable, or at best marginal, for horseshoe crab reproduction. Extensive bulkheading of eroding sandy beach along several New Jersey shore communities has further restricted the availability of suitable spawning habitat, making the remaining stretches of optimal sandy beach critical to the reproductive success of this species.     

A submodel for anaerobic mud-water exchange of phosphate

A submodel for anaerobic mud-water exchange of phosphate is obtained from experiments in the laboratory. Phosphorus in the sediment can be divided into exchangeable and non-exchangeable phosphorus. The exchangeable phosphorus is decomposed in accordance with a first-order reaction. The phosphorus moves, after the decomposition process, from the interstitial water to the water phase, in accordance with a diffusion expression. The yearly increase of the sediment was determined by means of the lead concentration as a function of the depth.