Toxic elements leaching in different soils affected by the spill from the aznalcollar pyrite mine (Sevilla,Spain)

A study has been made of the leaching of Cd, Zn, Pb, Cu, Tl and As in three representative soils of the zone affected by the spill from a pyrite mine in Aznalcollar (Sevilla, Spain) employing packed soil columns. According to the breakthrough and cumulative leaching curves, the relative mobilities of the different toxic elements in the columns are as follows: Tl > Cd > Zn > As > Cu > Pb. The results also show that the soils themselves have a good capacity for immobilizing the soluble fraction of the elements from the spilled mud, this capacity varying as follows: clayey soil with a high carbonate content > clayey soil with a moderate carbonate content > sandy‐clay loam soil with a low carbonate content. The results obtained in the work are a valuable contribution to the necessary assessment of the impact of the toxic spill on underground waters.     

The effect of macrophytes on retention times in a constructed wetland for wastewater treatment

Retention times of treated water in a constructed wetland (CW) with horizontal subsurface flow were determined both in the vegetative and non-vegetative periods of 2005. Tracer experiments were performed using fluorescein, an organic compound detectable at extremely low concentrations. Nominal and tracer retention times were determined and compared. Winter tracer retention time (TRT 194 h) and nominal retention time (nHRT 190 h) were nearly exactly equal, while summer TRT (335 h) was approximately twofold higher than nHRT (158 h). Residence time distribution function (RTD) was used to compare retention times obtained for the vegetative and non-vegetative periods. The obtained results document a significant influence of dense common reed vegetation on retention characteristics of the studied system. Common reed can convert a significant volume of water from liquid to gas via evapotranspiration (ET) and thus prolong water retention times in the system. This is very important both technically and ecologically. Longer retention times mean a longer time for microbiological decay of wastewater. Water converted from liquid to gas causes cooling of the microclimate, which is very important, especially in intensively cultivated areas with a lack of water.     

Quantitative assessment of the differential coastal vulnerability associated to oil spills

The risk associated with a given hazard (natural or technological) generally results from the interaction between the hazard potential and the vulnerability. This paper is centred on the assessment of the vulnerability variable. A quantitative vulnerability assessment and mapping methodology is proposed, with two main specificities: (1) it is hazard- and spatially-centred (respectively, oil spills and coastal areas) and; (2) the spatial segregation level used is the municipality. Due to the geographic context of the Portuguese mainland coast, the proposed methodology was applied in an attempt to illustrate the spatial distribution and the degree of the vulnerability associated to oil spills for mainland Portugal coastal municipalities. A final map is presented together with other informative elements. Analysis and discussion of the results allows for the understanding that: (1) there is a very heterogeneous and differential distribution of the degree of vulnerability to oil spills along the Portuguese coastline; (2) the application of specific hazard-centred and spatially-centred vulnerability assessment methodologies, comprising multi-dimensional indicators (e.g., geographic, ecological, demographic, social and economic), produces more robust and realistic results, highlighted by a thorough and spatially detailed analysis; and (3) future research is required on vulnerability assessment in Portugal; along side, hazard potential assessment methodologies must also be developed in order to create a final risk profile, which can be an extremely useful tool in spatial planning and management.     

Nonparametric circular methods for exploring environmental data

The goal of this work is to introduce nonparametric kernel methods for density and regression estimation for circular data, and illustrate their use by a brief simulation study and real data application. Apart from supplying practitioners with a license free and easy to run code for the use of these methods, our aim is also to provide solutions to practical problems that may be encountered in their application. The real data examples belong to the International Polar Year project, concerned with the environmental change in the polar regions.     

Mobilization of arsenic and other trace elements of health concern in groundwater from the Salí River Basin, Tucumán Province, Argentina

The Salí River Basin in north-west Argentina (7,000 km²) is composed of a sequence of Tertiary and Quaternary loess deposits, which have been substantially reworked by fluvial and aeolian processes. As with other areas of the Chaco-Pampean Plain, groundwater in the basin suffers a range of chemical quality problems, including arsenic (concentrations in the range of 12.2–1,660 μg L⁻¹), fluoride (50–8,740 μg L⁻¹), boron (34.0–9,550 μg L⁻¹), vanadium (30.7–300 μg L⁻¹) and uranium (0.03–125 μg L⁻¹). Shallow groundwater (depths up to 15 m) has particularly high concentrations of these elements. Exceedances above WHO (2011) guideline values are 100% for As, 35% for B, 21% for U and 17% for F. Concentrations in deep (>200 m) and artesian groundwater in the basin are also often high, though less extreme than at shallow depths. The waters are oxidizing, with often high bicarbonate concentrations (50.0–1,260 mg L⁻¹) and pH (6.28–9.24). The ultimate sources of these trace elements are the volcanic components of the loess deposits, although sorption reactions involving secondary Al and Fe oxides also regulate the distribution and mobility of trace elements in the aquifers. In addition, concentrations of chromium lie in range of 79.4–232 μg L⁻¹ in shallow groundwater, 129–250 μg L⁻¹ in deep groundwater and 110–218 μg L⁻¹ in artesian groundwater. All exceed the WHO guideline value of 50 μg L⁻¹. Their origin is likely to be predominantly geogenic, present as chromate in the ambient oxic and alkaline aquifer conditions.     

Joint use of data and modeling in coastal wave transformation

In the framework of a research project entitled ??BRISA??BReaking waves and Induced SAnd transport??, a methodology was devised to characterize the waves joining together in-situ measurements and numerical wave propagation models. With this goal in mind, a number of in-situ measurements were made, for selected positions in front of Praia de Faro (South Portugal), during four days (25th to 28th March, 2009) by using different types of equipments (e.g., resistive wave gauges, pressure sensors, currentmeters and a new prototype pore pressure sensor using optical fibre). Wave records were obtained simultaneously offshore (at a water depth of 11.7?m below mean sea level, MSL) and at the surf and swash zones. The data processing and analysis were made by applying classical time domain techniques. Numerical simulations of the wave propagation between offshore and inshore for the measurement period were performed with two numerical models, a 1D model based on linear theory and a nonlinear Boussinesq-type model, COULWAVE, both forced by the measured offshore wave conditions of 27th March 2009. Comparisons between numerical results and field data for the pressure sensors placed in the surf and swash zones were made and discussed. This approach enables to evaluate the performance of those models to simulate those specific conditions, but also to validate the models by gaining confidence on their use in other conditions.     

Towards the development of an operational tool for oil spills management in the Algarve coast

Portugal is strongly vulnerable to sea hazards due to intense vessel traffic and sea conditions. The southwest region off the Iberian Peninsula lies in the main route from the Mediterranean and Southern Hemisphere to the Northern Europe, causing a ship concentration in a narrow band off Cape S?o Vicente. Tankers represent a significant part of the vessel traffic and the occurrence of oil spills cannot be disregarded. Cape S?o Vicente region is part of a Natural Park with 110 Km of coastline, integrated in the European Natura 2000 network and its socio-economic context is closely related with sea resources exploitation, particularly fishing and tourism. Recognizing the importance of accurate information systems for the decision making process in an oil spill situation, this work presents the development of an integrated tool to support the process in the Algarve coast. The system relies in a regional operational mathematical model based on the MOHID modelling system. The system core is composed by three models (3D hydrodynamics, wave and Lagrangian transport) all linked in the same system and exchanging information in real time. Oil advection and weathering processes are coupled to the Lagragian transport model. The overall operational system includes external operational data products as inputs, to ensure a successful validation of the results. The system is linked to stakeholders and response authorities using a geographic referenced database based on Mapserver technology that will include relevant information for oil spill management.     

The productivity of mangroves in northwestern Mexico: a meta-analysis of current data

Mangroves constitute highly productive ecosystems that export organic material to surrounding areas. They reach their northernmost distribution on the American Pacific coast in arid northwestern Mexico where they grow under sub-optimal conditions. Nevertheless, they maintain high litterfall rates with important ecological and economical implications. These mangroves are threatened by the region??s accelerated development and population growth. In order to explore and describe large-scale patterns in the production of organic material and to assess their importance in the productivity of coastal ecosystems, we performed a meta-analysis of studies that measured mangrove litterfall in northwestern Mexico. We found that litterfall is strongly associated with latitude, and that evaporation was negatively correlated with it. Additionally, we found high correlation between the presence of Rhizophora mangle and productivity, while the presence of Laguncularia racemosa, showed a less pronounced trend. Despite the harsh conditions, mangroves produce high amounts of organic matter, which is perhaps the most important service of mangroves in these coasts. Their capacity to produce organic matter contrasts with that of their surrounding ecosystems. Substantial reductions in their surface will have consequences for the exchange of energy at the land-sea transition, which will be detrimental for biological communities and human populations.     

Life history strategy of a southern European population of brown shrimp (Crangon crangon L.): evidence for latitudinal changes in growth phenology and population dynamics

This study provides a comprehensive examination of the life cycle dynamics of the brown shrimp (Crangon crangon L.) in the Mondego estuary, Portugal, a habitat located near the southern edge of the range of this species in European waters. The phenology of all life stages was documented (from the occurrence of ovigerous females, developing embryos, planktonic larvae and benthic post-larvae), and migration patterns of larvae into and out of the estuary were examined. Temperature-dependent functions of egg and larval development were combined with data on field abundance to predict the timing and magnitude of occurrence of larvae and recruits. Compared to brown shrimp at higher latitudes, southern conspecifics grow slower, mature earlier and have smaller brood sizes, and larvae have a more protracted settlement period. The Mondego estuary, besides acting as nursery area, is a dynamic platform for C. crangon to use in different stages, sizes and seasons.     

Combining gut fluorescence technique and spatial analysis to determine <Emphasis Type="Italic">Littorina littorea</Emphasis> grazing dynamics in nutrient-enriched and nutrient-unenriched littoral mesocosms

Spatiotemporal distribution patterns in relation to feeding behavior of herbivorous gastropods have been studied extensively, but still knowledge about small-scale patterns is limited in relation to eutrophication. This experimental study aimed to describe the small-scale distribution of Littorina littorea in nutrient-enriched and nutrient-unenriched mesocosms in a merely atidal region and relate the distribution to food abundance and possible competing organisms, while checking simultaneously for feeding activities. The latter part was accomplished through the “gut fluorescence technique” GFT (which, to our knowledge, has not previously been used for benthic grazers) to estimate per capita grazing rates and the former part through monitoring of spatial heterogeneity of L. littorea and co-variation with sessile organisms (using semivariograms and cross-semivariograms, respectively). After 5 months of nutrient addition, the abundance and biomass of L. littorea had increased in enriched systems, which also had significantly higher total biomass of green algae. Gut pigment content was higher in L. littorea from enriched mesocosms, and gut depletion rate was higher in L. littorea from unenriched mesocosms. Spatial analysis showed that L. littorea exhibited generally random patterns (suggesting feeding activities) but sometimes (often in the morning) spatial patchiness (clumped distribution) in both enriched and unenriched conditions. There was mainly positive co-variation between L. littorea and biofilm, while different nutrient conditions exhibited contrasting co-variation between L. littorea and barnacles (positive co-variation in enriched and negative co-variation in unenriched mesocosms). The study offered insights into how feeding behavior and spatial distribution of a species may interact with community components differently under different nutrient regimes. The applied methodology can be useful for purposes of faster examination of grazing effects among different regions and also to compare grazing intensities and interactions between grazers and the benthic communities in disturbed (including pollution and nutrient enrichment) and non-disturbed systems, as well as in up-welling versus non-upwelling areas.