Minimization of the environmental impact of chrome tanning: a new process with high chrome exhaustion

In all tanning technology operations wastes are generated. These reach the environment as residual waters, solid and liquid waste as well as atmospheric emissions and odours.

This study tests an alternative method to the traditional tanning method at an industrial level. The new method is based on tanning without float and by significantly increasing the temperature at the end of the tanning process. The properties of the leathers obtained using the two methods have been compared and the results indicate that those leathers have similar physical, chemical, and organoleptic properties. However, the differences existing from the environmental point of view are significant. It is not necessary to use clean water for this tanning. Moreover, there is a 75% reduction of the residual float, a 91% reduction of the chrome discharged, and a 94% reduction of the chlorides discharged. A financial assessment was carried out to demonstrate that the newly proposed system is 32% more economic than the traditional one.     

Distribution of polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT) in Barcelona harbour sediments and their impact on benthic communities

Sediments have long been recognised as a sink for many contaminants like polycyclic aromatic hydrocarbons (PAHs) and tributyltin (TBT), which by virtue of their nature can strongly adsorb onto sediments affecting the benthic community inhabiting them. Using geographical information systems, this study reports and combines the results of several already existing studies along Barcelona harbour in order to assess the potential ecological impacts of these contaminants on the benthos of the harbour ecosystem. Chemical analysis indicated low to moderate contents of PAHs and high contents of TBT in sediments in Barcelona harbour. Comparison against existing sediment quality guidelines (SQGs) indicated that acutely toxic effects would not be expected for PAHs but for TBT, which represents a serious environmental threat for the benthic community. Benthos surveys revealed a deterioration of the benthic community throughout the harbour, especially in the inner port.     

Ten years measuring PCDDs/PCDFs in ambient air in Catalonia (Spain)

This work summarizes the results of a ten year surveillance programme on PCDD/F in ambient air carried out in Catalonia (Spain). The study has been conducted by the Dioxin Laboratory of Spanish Council for Scientific Research (CSIC) in collaboration with the Environment Department of the Catalonian Government. 175 samples have been collected throughout Catalonia from 1994 to 2004. Different sampling locations classified as industrial, traffic, urban, suburban and rural sites have been monitored in order to find the most contaminated zones as well as the ones with expected background concentrations. The highest concentrations found in this study were determined at the industrial locations. Concentrations ranging from 5 to 1196 fg I-TEQ/m3, with a mean value of 140 fg I-TEQ/m3 and from 10 to 357 fg I-TEQ/m3, with a mean value of 72 fg I-TEQ/m3 were determined in industrial and traffic sampling points, respectively. In contrast, the lowest concentrations were found in rural stations, ranging from 5 to 45 fg I-TEQ/m3, with a mean value of 28 fg I-TEQ/m3. The PCDD/F concentration trend in Catalonian ambient air shown a clear drop of the median values occurred during the study sampling period. A decline of about 70% was observed from 1997-1998 to 2003-2004.     

Identifying the origin of atmospheric inputs of trace elements in the Prades Mountains (Catalonia) with bryophytes, lichens, and soil monitoring

The biomonitors Hypnum cupressiforme and Xanthoria parietina were used to assess the deposition of trace elements and their possible origin in the Prades Mountains, a protected Mediterranean forest area of NE Spain with several pollution sources nearby. Al, As, Cd, Co, Cu, Cr, Ni, Pb, Sb, Ti, V, and Zn were determined in 16 locations within this protected area. Soil trace element concentrations were also ascertained to calculate enrichment factors (EF) and use them to distinguish airborne from soilborne trace element inputs. In addition, lichen richness was measured to further assess atmospheric pollution. EF demonstrated to be useful not only for the moss but also for the lichen. Cd, Cr, Cu, Ni, and Zn presented values higher than three in both biomonitors. These trace elements were also the main ones emitted by the potential sources of pollutants. The distance between sampling locations and potential pollution sources was correlated with the concentrations of Cu, Sb, and Zn in the moss and with Cr, Ni, and Sb in the lichen. Lichen richness was negatively correlated with lichen Cu, Pb, and V concentrations on dry weight basis. The study reflected the remarkable influence that the pollution sources have on the presence of trace elements and on lichen species community composition in this natural area. The study highlights the value of combining the use of biomonitors, enrichment factors, and lichen diversity for pollution assessment to reach a better overview of both trace elements’ impact and the localization of their sources.     

Valuation of climate-change effects on Mediterranean shrublands.

In general, the socioeconomic analysis of natural systems does not enter into the realms of natural science. This paper, however, estimates the human-welfare effects of possible physicochemical and biological impacts of climate change on Mediterranean shrublands over the coming 50 years. The contingent choice method was applied to elicit the trade-offs in perceived values for three climate-sensitive attributes of shrubland (plant cover, fire risk, and soil erosion) and for the costs of programs designed to mitigate changes. Soil erosion was found to be the attribute of shrubland that most concerned the population, followed by fire risk and then plant cover. An increase of 1% in the shrubland area affected by erosion was estimated to cost each person on average 2.9 euros per year in terms of lost welfare, a figure that is equivalent in terms of perceptions of social welfare to an increase of 0.24% in the shrub area burned annually and a decrease of 3.19% in the area of plant cover. These trade-off values may help ecologists, policy makers, and land managers to take social preferences into account.     

Patterns of mercury and methylmercury bioaccumulation in fish species downstream of a long-term mercury-contaminated site in the lower Ebro River (NE Spain)

Since the 19th century, large amounts of industrial waste were dumped in a reservoir adjacent to a chlor-alkali plant in the lower Ebro River (NE Spain). Previous toxicological analysis of carp populations inhabiting the surveyed area have shown that the highest biological impact attributable to mercury pollution occurred downstream of the discharge site. However, mercury speciation in fish from this polluted area has not been addressed yet. Thus, in the present study, piscivorous European catfish (Silurus glanis) and non-piscivorous common carp (Cyprinus carpio) were selected, to investigate the bioavailability and bioaccumulation capacities of both total mercury (THg) and methylmercury (MeHg) at the discharge site and downstream points. Multiple Correspondence Analysis (MCA) was applied to reduce the dimensionality of the data set, and Multiple Linear Regression (MLR) models were fitted in order to assess the relationship between both Hg species in fish and different variables of interest. Mercury levels in fish inhabiting the dam at the discharge site were found to be approximately 2-fold higher than those from an upstream site; while mercury pollution progressively increased downstream of the hot spot. In fact, both THg and MeHg levels at the farthest downstream point were 3 times greater than those close to the waste dump. This result clearly indicates downstream transport and increased mercury bioavailability as a function of distance downstream from the contamination source. A number of factors may affect both the downstream transport and increased Hg bioavailability associated with suspended particulate matter (SPM) and dissolved organic carbon (DOC).     

Mass scans from a proton transfer mass spectrometry analysis of air over Mediterranean shrubland browsed by horses

Plants usually emit large amount and varieties of volatiles after being damaged by herbivores. However, analytical methods for measuring herbivore-induced volatiles do not normally monitor the whole range of volatiles and the response to large herbivores such as large mammals is much less studied than the response to other herbivores such as insects. In this paper we present the results of using a highly sensitive proton transfer reaction-mass spectrometry (PTR-MS) technique that allows simultaneous monitoring of leaf volatiles in the pptv range. The resulting mass scans in air over Mediterranean shrubland browsed by horses show 70 to 100% higher concentrations of the masses corresponding to mass fragments 57, 43 and 41 (mostly hexenals, acetone and acetic acid) than scans over control non-browsed shrubland. These compounds are biogeochemically active and they are significant components of the volatile organic carbon found in the atmosphere. They influence the performance of living organisms and, the chemical and physical processes of Earth's atmosphere.     

A multi-criteria evaluation of organic amendments used to transform an unproductive shrubland into a Mediterranean dehesa

Environmental and health problems associated with the use of digested sewage sludge hinder its application and encourage the introduction of additional treatments such as composting and thermal drying. The aim of this paper is to assess the possibility of using three different types of sewage sludge (digested, composted and thermally dried) to improve soil fertility and enhance the transformation of an unproductive shrub land into a Mediterranean dehesa for grazing purposes and also to reduce wildfire risk. In total, 10t ha(-1) of dry matter of three types of sewage sludge were spread on the soil surface of 4x5m field plots, and then seeded with a mixture of grasses. Effects on soil fertility and plant growth were monitored over 2 years. The results show that all three types of sludge application had a significant effect on vegetation cover, herbaceous biomass (2767.7+/-716.1 and 1735.0+/-299.7kgha(-1) for digested sludge amended and control plots, respectively) and tree growth (0.41+/-0.108cmyear(-1) on amended trees, 14.6% more than control trees). This study proposes the use of multi-criteria analysis to identify the most suitable fertilization alternatives and to assist in the decision-making process of sludge recycling. Because of the high degree of uncertainty and conflicting objectives associated with these decisions, multi-criteria evaluation tools make a valuable contribution to decision-making processes concerning sewage sludge applications. According to multi-criteria results, the composted sludge alternative is the most suitable. This is because all the objectives are achieved: an improvement in the properties and functions of the soil with a positive vegetation response as well as minimal economic cost and risk of toxicity.