Toxicological availability of nickel to the benthic oligochaete Lumbriculus variegatus

It is generally accepted that the bioavailability of metals in sediments is influenced by the presence of acid volatile sulfides (AVS). The pore water hypothesis predicts that, if the molar concentration of simultaneously extracted metals (SEM) in a sediment is smaller than the molar concentration of AVS, the free metal ion activity in the pore water is very small and that consequently no metal toxicity in short-term toxicity tests is observed. In this study we examined (1) if this concept can be extended to predict the absence of chronic Ni toxicity to the oligochaete deposit-feeding worm Lumbriculus variegatus and (2) if the organic carbon normalized excess SEM; i.e. [SEM-AVS]/f(OC) predicts the magnitude of Ni toxicity to L. variegatus. A 28-day toxicity experiment was performed in which biomass production of L. variegatus was determined in two natural sediments with different [AVS] and f(OC), spiked at different Ni concentrations. The absence of toxicity is predicted correctly by the [SEM-AVS]<0 criterion when only the 0-1 cm surface layer of the sediment is considered, but not when the whole bulk sediment is considered (0-3 cm). In both sediments, the same [SEM-AVS]/f(OC) at the surface corresponds with a similar decrease in L. variegatus biomass. Thus, [SEM-AVS]/f(OC) in the surface layer accurately predicts the magnitude of toxicity. This measure is therefore a good estimator of toxicologically available Ni. On the other hand, the free Ni(2+) ion activity in the overlying water appeared to be an equally good predictor of the magnitude of toxicity. Consequently, it was not possible to determine the relative importance of the overlying water and pore water exposure route with the semi-static laboratory experiments.     

Land take and food security: assessment of land take on the agricultural production in Europe

Soil is a multifunctional, non-renewable natural resource for Europe as clearly expressed in the European Union (EU) Thematic Strategy for Soil Protection (COM (2006)231). Soil carries out multiple functions, including the support of food production. Urban development and its associated land take poses a major threat to soil and could have significant effects on agricultural production. This paper aims to evaluate the potential productivity losses in European agriculture due to land-take processes between 1990 and 2006. Agricultural land take was calculated using CORINE Land Cover maps of 1990, 2000 and 2006. For 21 of the 27 EU member states, agricultural land take was computed to be 752,973 ha for 1990–2000 and 436,095 ha for 2000–2006, representing 70.8% and 53.5%, respectively, of the total EU land take for these periods. The impact of this land take on the production capabilities of the agricultural sector for the period 1990–2006 for 19 of the 21 states was estimated to be equivalent to a loss of more than six million tonnes of wheat. The paper demonstrates that Europe's intense urbanisation has a direct impact on its capability to produce food.     

Constructive conflict at work

Two field studies of interpersonal conflict in organizations and a simulated dyadic negotiation show that problem solving and forcing are frequently combined simultaneously and sequentially. As a robust finding, conglomerations of problem solving and forcing appear to enhance the parties' joint effectiveness. The best substantive and relational outcomes for the organization are reached through forcing followed by problem solving. Copyright © 1999 John Wiley & Sons, Ltd.     

The influence of age on the associations between HR practices and both affective commitment and job satisfaction: A meta-analysis

Research on the association between high commitment Human Resource (HR) practices and work-related outcomes at the individual level rarely focuses on age differences. To fill this knowledge gap, a meta-analysis has been conducted to examine how the relationships between the availability of high commitment HR practices, as perceived by employees, and affective commitment and job satisfaction change with age. Drawing on Selection, Optimization, and Compensation (SOC) theory and on Regulatory Focus theory, we identify a bundle of maintenance HR practices and a bundle of development HR practices, and hypothesize that the association between maintenance HR practices and work-related attitudes strengthens with age, and that the association between development HR practices and work-related attitudes weakens with age. Our meta-analysis of 83 studies reveals that, in line with social exchange and signaling theories, employees' perceptions of HR practices are positively related to their work-related attitudes, and that calendar age influences this relationship largely as expected. These results are discussed in light of the above mentioned theories. Copyright © 2009 John Wiley & Sons, Ltd.     

ARSENIC POISONING IN BANGLADESH: A GEOGRAPHIC ANALYSIS1

ABSTRACT: Drinking of arsenic‐contaminated tubewell water has become a serious health threat in Bangladesh. Arsenic contaminated tubewells are believed to be responsible for poisoning nearly two‐thirds of this country's population. If proper actions are not taken immediately, many people in Bangladesh will die from arsenic poisoning in just a few years. Causes and consequences of arsenic poisoning, the extent of area affected by it, and local knowledge and beliefs about the arsenic problem — including solutions and international responses to the problem — are analyzed. Although no one knows precisely how the arsenic is released into the ground water, several contradictory theories exist to account for its release. Initial symptoms of the poisoning consist of a dryness and throat constriction, difficulty in swallowing, and acute epigastric pain. Long‐term exposure leads to skin, lung, or bladder cancer. Both government and nongovernmental organizations (NGOs) in Bangladesh, foreign governments, and international agencies are now involved in mitigating the effects of the arsenic poisoning, as well as developing cost‐effective remedial measures that are affordable by the rural people.     

Role of peat organic matter on isotopic composition of most abundant benthic organisms in intertidal habitats of SW Iceland

The transfer of peat organic matter (OM) from tidal pools of upper littoral to downstream rocky shores and its potential incorporation into marine biota were investigated using the stable isotope approach. Samplings were carried out in September 2004 in two SW Icelandic sites (Osar and Hvassahraun), where we selected (1) areas with shores where grass gently declined towards rocks and, on reaching the sea line, formed small tidal peat pools and (2) areas where grass and rocky shores were not contiguous, rather the grass lower limits were several hundreds of meters back from the shore. In both grass and no grass areas, in the intertidal zone, all benthic organisms and all potential OM sources were sampled. Dominant macroalgae were Ascophyllum nodosum ([Linnaeus] Le Jolis) and Fucus vesiculosus Linnaeus. In grass sites, organisms partially reflected the isotopic composition of peat OM, while in no grass sites, peat represented only a negligible amount of available OM, or its signal was totally absent from the environment. Intertidal organisms could rely on peat both directly by suspension feeding, grazing or scavenging and indirectly by predation (crabs) on low level consumers (barnacles).     

Phylogeography, historical demography, and the role of post-settlement ecology in two Hawaiian damselfish species

Coral reef fish generally have relatively sedentary juvenile and adult phases and a presumed highly dispersive pelagic larval phase, yet previous studies that have tried to relate pelagic larval duration (PLD) to population structure have given inconsistent results. In the present study, the population structures of two damselfishes, Stegastes fasciolatus and Dascyllus albisella, were examined using mitochondrial control region sequences. The two species have similar PLDs (∼25 and 27 days respectively), but consistently differ in their settlement preferences, habitat, and densities in populations throughout the Hawaiian Archipelago, from Hawaii north to Kure Atoll, and south to Johnston Atoll. Information on habitat preferences and population densities were collected between September 2000 and October 2002, and tissue samples for the genetic studies were collected between January and April 2004. Based on the differences in habitat and abundance of the two species, the expectation was that S. fasciolatus would have high genetic variability but little population structure compared to D. albisella, and this was largely confirmed. Stegastes fasciolatus had little population structure in most of the Hawaiian Islands, and D. albisella showed evidence of strong population structure throughout its range. An exception to this pattern was the large difference between the Kure Atoll population of S. fasciolatus and all others. These results suggest that the interaction of several biological factors (e.g. species-specific spawning habitat and season) with environmental factors (e.g. seasonal wind and current patterns) may have more influence on population structure than single life history characteristics, such as the PLD.     

Root-surface phosphatase activity in shrublands across a European gradient: effects of warming

Root-surface phosphatase activities were measured in natural and semi-natural shrublands across an European climatic gradient of temperature and rainfall including Wales (WL), Denmark (DK), Netherlands (NL), Hungary (HU), Italy (IT) and Spain (SP). In each site a warming experiment was conducted since 1999 or 2001 by means of passive night-time warming using reflective curtains that covered the vegetation at night. The treatments increased yearly average soil temperatures around 0. 8 degrees C in most of sites. Root-surface phosphatase activity values ranged between 56 mg PNP g(-1) h(-1) in IT and 3.5 mg PNP g(-1) h(-1) in HU. Warming had no effect on root-surface phosphatase activity across the sites and only in Hungary a slight increase was detected. Plants at Mediterranean sites (IT, SP) showed a higher root-surface phosphatase activity than plants at temperate sites (WL, NL, DK). We suggest it might be an adaptation of plant species evolved under Mediterranean climate that allows them a) to compensate in wet period for the decrease in phosphatase activity, and thus P uptake, during drought periods, and/or b) to benefit from soluble organic P flushes following the frequent drying-rewetting episodes experienced by soils in Mediterranean ecosystems.     

Vegetation, Soil, and Animal Indicators of Rangeland Health

We studied indicators of rangeland health on benchmark sites with long, well documented records of protection from stress by domestic livestock or histories of environmental stress and vegetation change. We measured ecosystem properties (metrics) that were clearly linked to ecosystem processes. We focused on conservation of soil and water as key processes in healthy ecosystems, and on maintenance of biodiversity and productivity as important functions of healthy ecosystems. Measurements from which indicators of rangeland health were derived included: sizes of unvegetated patches, cover and species composition of perennial grasses, cover and species composition of shrubs and herbaceous perennials, soil slaking, and abundance and species composition of the bird fauna. Indicators that provided an interpretable range of values over the gradient from irreversibly degraded sites to healthy sites included: bare patch index, cover of long-lived grasses, palatability index, and weighted soil surface stability index. Indicators for which values above a threshold may serve as an indicator of rangeland health include: cover of plant species toxic to livestock, cover of exotic species, and cover of increaser species. Several other indicator metrics were judged not sensitive nor interpretable. Examples of application of rangeland health indicators to evaluate the success of various restoration efforts supported the contention that a suite of indicators are required to assess rangeland health. Bird species diversity and ant species diversity were not related to the status of the sample site and were judged inadequate as indicators of maintenance of biodiversity.     

Comparative analysis of forest canopy mapping methods for the Sundarban biosphere reserve,West Bengal,India

The canopy density of forests is highly influenced by population pressure which cause forest fragmentations, deforestations, forest degradation and also land reclamation for infrastructure and agriculture. This study was envisaged with the objective of mapping the forest canopy density with two different methods by using Landsat 8 OLI dataset of the year 2016 after mapping the vegetation indices. One of the two methods is the semi-expert FCD mapper model, while the other model is newly developed by us and consists of eight vegetation indices. After running the models, the results of both the models were compared. It was found that for the semi-expert FCD model, the three classes viz. high canopy density, moderate canopy and low canopy covered an area of 81,615.51 ha (40%), 84,474.72 ha (41%) and 38,844.18 ha (19%), respectively. And for the modified FCD model, the same classes covered 69,134.670 ha (37%), 84,062.250 ha (45%) and 32,529.150 ha (18%), respectively. It was observed that the difference between semi-expert FCD model and the modified FCD model’s accuracy is about 1.75% and difference in Kappa statistics is 0.0362. Thus, the modified model is more accurate than the semi-expert FCD model and gives us more detailed canopy density map than the semi-expert FCD map.