Cross‐level effects of demography and diversity climate on organizational attachment and firm effectiveness

We studied the impact of demographic diversity on individual attachment and firm unit performance in a relatively diverse organization. We implemented cross‐level regression to study gender and race/ethnic categorical, relational, and organizational demography in a sample of 26 units part of a regional restaurant chain. At the individual level, we found that diversity climate (DC) moderates the impact of relational and categorical demography on affective organizational commitment, organizational identification, and intention to quit. At the organizational level, we found that DC moderates the impact of organizational diversity on firm productivity and return on profit. We discuss the importance of organizational DC as organizational context on individual attachment, and implications for firm effectiveness in diverse organizations. Copyright © 2007 John Wiley & Sons, Ltd.     

Effects of climate change on species distribution, community structure, and conservation of birds in protected areas in Colombia

Climate change is expected to cause shifts in species distributions worldwide, threatening their viability due to range reductions and altering their representation in protected areas. Biodiversity hotspots might be particularly vulnerable to climate change because they hold large numbers of species with small ranges which could contract even further as species track their optimal habitat. In this study, we assessed the extent to which climate change could cause distribution shifts in threatened and range-restricted birds in Colombia, a megadiverse region that includes the Tropical Andes and Tumbes-Choco-Magdalena hotspots. To evaluate how climate change might influence species in this region, we developed species distribution models using MAXENT. Species are projected to lose on average between 33 and 43 % of their total range under future climate, and up to 18 species may lose their climatically suitable range completely. Species whose suitable climate is projected to disappear occur in mountainous regions, particularly isolated ranges such as the Sierra Nevada de Santa Marta. Depending on the representation target considered, between 46 and 96 % of the species evaluated may be adequately represented in protected areas. In the future, the fraction of species potentially adequately represented is projected to decline to 30–95 %. Additional protected areas may help to retain representativeness of protected areas, but monitoring of species projected to have the largest potential declines in range size will be necessary to assess the need of implementing active management strategies to counteract the effects of climate change.     

In situ experiments for element species-specific environmental reactivity of tin and mercury compounds using isotopic tracers and multiple linear regression

The fate of mercury (Hg) and tin (Sn) compounds in ecosystems is strongly determined by their alkylation/dealkylation pathways. However, the experimental determination of those transformations is still not straightforward and methodologies need to be refined. The purpose of this work is the development of a comprehensive and adaptable tool for an accurate experimental assessment of specific formation/degradation yields and half-lives of elemental species in different aquatic environments. The methodology combines field incubations of coastal waters and surface sediments with the addition of species-specific isotopically enriched tracers and a mathematical approach based on the deconvolution of isotopic patterns. The method has been applied to the study of the environmental reactivity of Hg and Sn compounds in coastal water and surface sediment samples collected in two different coastal ecosystems of the South French Atlantic Coast (Arcachon Bay and Adour Estuary). Both the level of isotopically enriched species and the spiking solution composition were found to alter dibutyltin and monomethylmercury degradation yields, while no significant changes were measurable for tributyltin and Hg(II). For butyltin species, the presence of light was found to be the main source of degradation and removal of these contaminants from surface coastal environments. In contrast, photomediated processes do not significantly influence either the methylation of mercury or the demethylation of methylmercury. The proposed method constitutes an advancement from the previous element-specific isotopic tracers’ approaches, which allows for instance to discriminate the extent of net and oxidative Hg demethylation and to identify which debutylation step is controlling the environmental persistence of butyltin compounds.     

Perfluorooctanesulfonate and related fluorochemicals in biological samples from the north coast of Colombia

Perfluorinated compounds are widespread pollutants of toxicological importance that have been detected in environmental matrices. However, little is known on their distribution in South America. In this study, distribution of perfluorooctanesulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluorohexanesulfonate (PFHxS), and perfluorooctanesulfonamide (PFOSA) was determined in the bile of mullet, Mugil incilis, and in tissues of pelicans (Pelecanus occidentalis) collected from North Colombia. Analysis was performed by HPLC mass spectrometry after ion-pair extraction. PFOS was found in all bile samples and PFOA and PFHxS were detected at lower frequency. Average concentrations of PFOS, PFOA, and PFHxS in bile of fish from Cartagena Bay, an industrialized site, and Totumo marsh, a reference site, were 3673, 370, 489 and 713, 47.4, 1.27 ng/mL, respectively. PFOS concentrations in pelican organs decreased in the order of spleen>liver>lung>kidney>brain>heart>muscle. These results suggest, for the first time, that perfluorinated compounds are also found in wildlife from Latin American countries.     

The uptake of hydrogen fluoride by a forest

A mathematical model of hydrogen fluoride (HF) deposition and accumulation of fluoride in a Eucalyptus rostrata forest has been developed. The model is based on tree physiology and meteorological principles. The data base for the model was derived from a literature survey of the physiological characteristics of E. rostrata and similar eucalyptus species and from current knowledge of meteorological processes in plant canopies.Comparison of the mathematical simulations with measurements in the vicinity of a source of HF (an aluminium reduction plant) shows that (1) the pattern of seasonal fluoride accumulation in leaves agrees with that seen in the field, and (2) the vertical pattern of accumulation inside tree leaves agrees with field observations. The simulations indicate that 50% of the released HF was deposited within 81 km of the source and that the concentration of HF in the air 81 km from the source was reduced to 2% of the concentration 1 km from the source. However, a very large forest area (20 600 km²) was required to achieve these reductions.     

Trace metal residues in tissues of two crustacean species from the Bahia Blanca Estuary,Argentina

Trace metals (total mercury, cadmium and zinc) were studied in several tissues of the edible shrimps Pleoticus muelleri and Artemesia longinaris from the Bahía Blanca estuary, Argentina. The digestive gland was shown to be the main organ in which metals accumulate, followed by the stomach-alimentary canal and abdominal muscle.The metal contents found in the present study largely exceeded those of the same species caught from the Argentine Sea. Mercury concentrations increased proportionally to the total length of the shrimps studied. Only little variation in metal concentrations among individuals seemed to exist.Finally, the usefulness of these species as bioindicators of trace metal pollution in the Bahía Blanca estuary is discussed.     

Distribution of Heavy Metals in Surface Sediments from an Antarctic Marine Ecosystem

The concentrations of lead, cadmium, copper,chromium, iron, manganese and zinc in surfacesediments collected from Potter Cove, in the 25de Mayo Island (King George Island), Antarctica, andits drainage basin, were measured by atomic absorptionspectroscopy. The obtained results were use todetermine the areal and vertical distribution of themetals of in the Cove and potential sources of thesemetals to this environment. The geochemical datasuggest that most of the metals found in Potter Coveconstitute a redistribution of autochthonous materialswithin the ecosystem. Therefore, the metalconcentrations can be considered to be present atnatural background levels in surface sediments.