National and regional determinants of tropical deforestation in Colombia

Global tropical deforestation continues to occur at high rates despite political attention. National-level forest baselines are being established all over the world to guide the implementation of several policy mechanisms. However, identifying the direct and indirect drivers of deforestation and understanding the complexity of their interlinkages are often difficult. We first analyzed deforestation between 1990 and 2005 at the national level and found an annual deforestation rate of 0.62 %. Next, we performed separate analyses for four natural regions in Colombia and found annual deforestation rates between 0.42 and 1.92 %. Using general linear models, we identified several direct causes and underlying factors influencing deforestation at the national level: rural population density, cattle, protected areas, and slope. Significant differences in deforestation rates and causes were found across regions. In the Caribbean region, drivers of loss are urban population, unsatisfied basic needs, slope, and precipitation and four land use variables (illicit crops, pastures, cattle, and fires). In the Orinoco region, crops are the main driver of forest loss, and in the Amazonian region, deforestation is primarily due to fires related to the colonization front. Policy mechanisms will have to take into account regional patterns to successfully balance development and forest preservation in Colombia.     

A model for estimating the impact of the domino effect on accident frequencies in quantitative risk assessments of storage facilities

It is well known that the domino effect can have a major impact on accidents in storage facilities, as it can increase the consequences of an initial event considerably. However, quantitative risk assessments (QRAs) do not usually take the domino effect into account in a detailed, systematic way, mostly because of its complexity and the difficulties involved in its incorporation. We have developed a simple method to include the domino effect in QRAs of storage facilities, by estimating the frequency with which new accidents will occur due to this phenomenon. The method has been programmed and implemented in two case studies. The results show that it can indeed be used to include the possibility of domino effect occurrence in a QRA. Furthermore, depending on the design of a facility, the domino effect can have a significant effect on the associated risk.     

Study on PCDDs/PCDFs and co-PCBs content in food samples from Catalonia (Spain)

The results of a surveillance programme on polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and co-planar polychlorinated biphenyls (co-PCBs) determination in 70 foodstuffs samples produced all over the four provinces of Catalonia is presented. The study included the analyses of raw milk, pure virgin olive oil, butter, chicken, pork and mussel samples collected between November 1999 and January 2000. Milk, virgin oil, pork or butter presented a variable dioxin and co-PCBs content, even though the limits proposed in the draft of the EC Regulation for its commercialization in the European countries were not reached. The levels of PCDDs/PCDFs and co-PCBs determined in chicken samples varied between 0.36–3.59 pg I-TEQ/g fat chicken (0.4–3.8 WHO-TEQ/g fat). Just one case presented remarkable content of dioxins (about 30 pg I-TEQ/g fat) with a complex congener-specific profile which indicates the presence of an external contamination. On the other hand, a congener-specific profile dominated by 2,3,7,8-TCDF and OCDD was observed in mussel samples from Catalonia. This fact was also observed in mussel samples from other sites in Spain.     

Accumulation of As, Cd and selected trace elements in tubers of Scirpus maritimus L. from Doñana marshes (South Spain)

The collapse of a pyrite-mining, tailing dam on 1998 contaminated an area of 4286 ha along the Agrio and Guadiamar river valleys in southern Spain. Over 2700 ha of the Do?ana marshes, an important wintering area for wetland European birds, were contaminated. This study reports analyses of the tubers of Scirpus maritimus (an important food for greylag geese, Anser anser) collected in 2000 in the "Entremuros" (spill-affected area) and in nearby unaffected Do?ana marshes (control areas). In the spill-affected area mean tuber tissue concentrations of Cd (0.25 mg kg-1) and Zn (61 mg kg-1) were greater than in those tubers from the control area (0.02 mg kg-1 for Cd, and 22 mg kg-1 for Zn); values of Cd and Zn in "Entremuros" (samples collected two years after the mine spill) were much smaller than those reported only a few months after the accident. Trace elements (As, Fe, Mn and Tl, and to a lesser extent Cd and Pb) showed a preferential accumulation in the outer skin of tubers. Surprisingly, concentrations of As and Fe were greater in tubers from some marsh sites not affected by the mine-spill than in tubers from the "Entremuros". We suggest that relic river channels within the Do?ana marshes may be contaminated by trace elements from historic mining activities. An exhaustive study of macrophytes and other plant species in this area is recommended to identify potential risks to wildlife.     

Occurrence and degradation of butyltins and wastewater marker compounds in sediments from Barcelona harbor, Spain

Contamination of Barcelona harbor sediments was assessed by the quantitative determination of butyltins (TBT, DBT and MBT) and surfactant intermediates, namely linear alkylbenzenes (LABs) and nonylphenols (NPs), as markers of urban and industrial wastewater contamination, respectively. Degradation indexes of TBT and LABs were calculated. Tributyltin predominated in the whole area over its degradation products, ranging from 98 to 4702 ng Sn/g. These elevated concentrations reveal a persistent historical contamination and a moderate degradation (BT(deg)). Moreover, the high LAB concentrations (1.2-53.1 microg/g) compared to the relatively low NP levels (3.8-72.0 ng/g) suggest a predominance of urban over industrial wastewater inputs, although a significant correlation (r(2) = 0.82, N = 12, P = 0.001) between LABs and NPs was found. Stormwater runoff and combined sewer overflows (CSO) were likely the most possible sources for both surfactant intermediates. The high degradation index values obtained for LABs could indicate an improvement in the wastewater management reducing its recent discharge into the Barcelona harbor area.     

High self-recruitment levels in a Mediterranean littoral fish population revealed by microsatellite markers

Self-recruitment rates are essential parameters in the estimation of connectivity among populations, having important consequences in marine conservation biology. Using ten highly polymorphic microsatellite loci, we estimate, over 3 years, the self-recruitment in a population of Tripterygion delaisi in the NW Mediterranean. Six previously described source populations were used for the assignment (Costa Brava, Columbretes, Formentera, Cabo de Palos, Cabo de Gata and Tarifa). Even though this species has a 16–21 day larval duration, a mean of 66.4 ± 1.4% of the recruits settled in their natal population. When refining in a more local scale the origin of individuals self-recruited to Costa Brava, using as source the three sampling localities that conform this population (Cap de Creus, Tossa and Blanes), the highest percentage (40.6 ± 8.9%) was self-assigned to the adult source locality (Blanes) where recruits were sampled each year. Our results suggest that a high proportion of the larvae of T. delaisi remained close to, or never leave, their natal spawning area. This observation can be extrapolated to other species with similar early life-history traits and low adult mobility and can have important implications for the conservation and management of Mediterranean littoral fishes.     

A Classification Procedure for Mapping Topo-climatic Conditions for Strategic Vegetation Planning

Environmental classification addresses issues involving the representation and analysis of continuous and variable ecological data. This study creates a methodology to define topo-climatic landscapes (TCL) in the north-west of Catalonia, which is situated in the north-east of the Iberian Peninsula. TCL provide data regarding the ecological behavior of a landscape in terms of its topography, physiognomy, and climate, which are the main drivers of an ecosystem. The variables selected are derived from a variety of different sources, such as remote sensing and climatic atlases. The methodology employed combines unsupervised iterative cluster classification with supervised fuzzy classification. Twenty eight TCL, which can be differentiated in terms of their vegetation physiognomy and vegetation altitudinal range type, were selected for the study area. Furthermore, a hierarchy among the TCL is established which permits the merging of clusters and allows for changes in thematic resolution. By using the topo-climatic landscape map, managers can identify patches with similar environmental conditions and at the same time assess the uncertainty involved in classification.     

A large scale survey of trace metal levels in coastal waters of the Western Mediterranean basin using caged mussels (Mytilus galloprovincialis)

A large scale study of trace metal contamination (Hg, Cd, Pb and Ni) by means of caged mussels Mytilus galloprovincialis was undertaken along the coastal waters of the Western Mediterranean Sea within the context of the MYTILOS project. Individual mussels from an homogeneous population (shell size 50 ± 5 mm) obtained from an aquaculture farm were consecutively caged and deployed at 123 sites located in the Alborán, North-Western, South-Western and Tyrrhenian sub-basins for 12 weeks (April-July) in 2004, 2005 and 2006. After cage recoveries, both the metal content in the whole mussel tissue and the allometric parameters were measured. Statistical analysis of the datasets showed significant differences in concentrations between sub-basins for some metals and mussel condition index (CI). Linear regression models coupled to the CI were revisited for the data adjustment of certain trace metals (Hg, Cd and Ni), and four level categories were statistically derived to facilitate interregional comparison. Seawater masses surrounding coastal areas impacted by run-off from land mineralised coasts and industrial activities displayed the highest concentration ranges (Hg: 0.15-0.31 mg kg(-1) dw; Cd: 1.97-2.11; Ni: 2.18-3.20 and Pb: 3.1-3.8), although the levels obtained in most of the sites fitted within moderate or low categories, and they could be considered as baseline concentrations. However, few sites considered little-influenced by human activities, at present, showed high concentrations of Cd, Ni and Pb, which constitute new areas of concern. Overall, the use of active biomonitoring (ABM) approach allowed to investigate trace metal contamination in order to support policy makers in establishing regional strategies (particularly, with regard to the European Marine Strategy Directive).