Surveillance programme on dioxin levels in soils in the Campo de Gibraltar (southwest Spain)

The results of an epidemiologic study undertaken by the Spanish Council for Scientific Research (CSIC) after commission by the Spanish Parliament indicated that Huelva and Cádiz were the zones in Andalusia with elevated risk of cancer. A 6% (women) and 10% (men) cancer mortality excess was observed with respect to the other six Andalusian provinces. Huelva and Cádiz are located in the south-western region of Spain, and are characterized by a strong industrial activity concentrated in several industrial sites. This situation led to two environmental surveys in these areas, in which the presence of dioxins was studied among other parameters. A PCDD/F assessment in soils of the Campo de Gibraltar (Cádiz) was carried out from June 2003 to June 2004. A total of 20 samples were collected in this study divided in two sampling campaigns. The first 10 samples were taken in locations affected by high industrial activity zones as well as in landfills (hotspots). The rest of the samples were collected in areas that were not expected to be contaminated, such as agricultural zones and forests. I-TEQ values of the samples ranged from 0.26 to 15.08 ng/kg dm. In all, 85% of the samples were below the limit of 5 ng I-TEQ/kg I-TEQ concentrations of three samples only surpassed this limit. These zones corresponded to a landfill, a quarry used for dumping chemical product containers and a sample from the sewage system of the industrial site. These sites were used neither for agricultural nor for public purposes.     

Geochemistry of leachates from the El Fraile sulfide tailings piles in Taxco, Guerrero, southern Mexico

Leachates from the El Fraile tailings impoundment (Taxco, Mexico) were monitored every 2 months from October 2001 to August 2002 to assess the geochemical characteristics. These leachates are of interest because they are sometimes used as alternative sources of domestic water. Alternatively, they drain into the Cacalotenango creek and may represent a major source of metal contamination of surface water and sediments. Most El Fraile leachates show characteristics of Ca–SO₄, (Ca+Mg)–SO₄, Mg–SO₄ and Ca–(SO₄+HCO₃) water types and are near-neutral (pH=6.3–7.7). Some acid leachates are generated by the interaction of meteoric water with tailings during rainfall events (pH=2.4–2.5). These contain variable levels of SO₄ ²⁻ (280–29,500 mg l⁻¹) and As (<0.01–12.0 mg l⁻¹) as well as Fe (0.025–2352 mg l⁻¹), Mn (0.1–732 mg l⁻¹), Zn (<0.025–1465 mg l⁻¹) and Pb (<0.01–0.351 mg l⁻¹). Most samples show the highest metal enrichment during the dry seasons. Leachates used as domestic water typically exceed the Mexican Drinking Water Guidelines for sulfate, hardness, Fe, Mn, Pb and As, while acidic leachates exceed the Mexican Guidelines for Industrial Discharge Waters for pH, Cu, Cd and As. Speciation shows that in near-neutral solutions, metals exist mainly as free ions, sulfates and bicarbonates, while in acidic leachates they are present as sulfates and free ions. Arsenic appears as As^(V) in all samples. Thermodynamic and mineralogical evidence indicates that precipitation of Fe oxides and oxyhydroxides, clay minerals and jarosite as well as sorption by these minerals are the main processes controlling leachate chemistry. These processes occur mainly after neutralization by interaction with bedrock and equilibration with atmospheric oxygen.     

Antimony content of macrofungi from clean and polluted areas

Species of macrofungi (mushrooms) were collected from clean areas and analyzed for their antimony content. These were compared to species collected from extremely polluted areas in the vicinity of a lead smelter and on mine and slag dumps. Antimony content was determined using long-term instrumental neutron activation analysis (INAA). Ectomycorrhizal and terrestrial saprobic macrofungi were examined. Antimony content of macrofungi from the clean areas was mostly less than 100 μg kg⁻¹ (dry mass). The highest concentrations (units of mg kg⁻¹) were found in various species of the ectomycorrhizal genera Chalciporus and Suillus. Antimony contents of macrofungi growing in the polluted areas were considerably higher. The highest content was found in a single collection of Chalciporus piperatus (1423 mg kg⁻¹).     

Immobilization of heavy metals in polluted soils by the addition of zeolitic material synthesized from coal fly ash

The use of zeolitic material synthesized from coal fly ash for the immobilization of pollutants in contaminated soils was investigated in experimental plots in the Guadiamar Valley (SW Spain). This area was affected by a pyrite slurry spill in April 1998. Although reclamation activities were completed in a few months, residual pyrite slurry mixed with soil accounted for relatively high leachable levels of trace elements such as Zn, Pb, As, Cu, Sb, Co, Tl and Cd. Phytoremediation strategies were adopted for the final recovery of the polluted soils. The immobilization of metals had previously been undertaken to avoid leaching processes and the consequent groundwater pollution. To this end, 1100 kg of high NaP1 (Na6[(AlO2)6(SiO2)10] .15H2O) zeolitic material was synthesized using fly ash from the Teruel power plant (NE Spain), in a 10 m3 reactor. This zeolitic material was manually applied using different doses (10000-25000 kg per hectare), into the 25 cm topsoil. Another plot (control) was maintained without zeolite. Sampling was carried out 1 and 2 years after the zeolite addition. The results show that the zeolitic material considerably decreases the leaching of Cd, Co, Cu, Ni, and Zn. The sorption of metals in soil clay minerals (illite) proved to be the main cause contributing to the immobilization of these pollutants. This sorption could be a consequence of the rise in pH from 3.3 to 7.6 owing to the alkalinity of the zeolitic material added (caused by traces of free lime in the fly ash, or residual NaOH from synthesis).     

Characterization of surface marine sediments from Ría de Arousa estuary according to extractable humic matter content

Surface marine sediments from Ría de Arousa estuary were analyzed for humic and fulvic acids by UV-visible spectrometry and have been characterized using elemental analysis (carbon, hydrogen and nitrogen elemental composition) and spectrometric data (A2/A4 ratio, absorbancies at 270 and 407 nm and E4/E6 ratio, absorbancies at 465 and 665 nm). These variables have been used as discriminating factors to distinguish of marine and terrestrial origin of humic and fulvic acids in Ría de Arousa surface marine sediments. Principal component analysis, PCA, and cluster analysis, CA, have been used as unsupervised pattern recognition procedures. The half-range central value transformation was used as data pre-treatment to homogenize data. After a Varimax rotation, PCA applied to humic acid data has reveled that spectrometric A2/A4 and E4/E6 ratios are the main dominating features in the first principal component (48.6% of total variance), the humic acid content is the feature with the highest weight in the second principal component (22.9% of the total variability) and the carbon elemental composition domain in the third principal component (13.3% of total variance). Results from PCA have revealed that surface sediments collected at inner-left part of the estuary and at the mouth of the river Ulla belong to the same group. Similarly, PCA has shown that surface sediments from the right mouth of the estuary form a compact group. Taking in account the water circulation in Ría de Arousa estuary, these findings mean that the organic matter in surface sediments from the inner-left part of the estuary derived mainly from terrestrial organic matter while the organic matter in surface sediments from the right mouth of the estuary is mainly derived from marine sources. Finally, it must be noticed that any classification of surface sediments was assessed when applying of PCA and CA from fulvic acids data.     

An in situ postexposure feeding assay with Carcinus maenas for estuarine sediment-overlying water toxicity evaluations

This study developed and evaluated a short-term sublethal in situ toxicity assay for estuarine sediment-overlying waters, with the crab Carcinus maenas (L.) based on postexposure feeding. It consisted of a 48-h in situ exposure period followed by a short postexposure feeding period (30 min). A precise method for quantifying feeding, using the Polychaeta Hediste (Nereis) diversicolor Müller as food source, was first developed. The sensitivity of the postexposure feeding response was verified by comparing it to that of lethality, upon cadmium exposure. The influence of environmental conditions prevailing during exposure (salinity, temperature, substrate, light regime, and food availability) on postexposure feeding was also addressed. The potential of this in situ assay was then investigated by deploying organisms at ten sites, located in reference and contaminated Portuguese estuaries. Organism recovery ranged between 90% and 100% and a significant postexposure feeding depression (16.3-72.7%) was observed at all contaminated sites relatively to references.     

California sea lions (Zalophus californianus californianus) have lower chlorinated hydrocarbon contents in northern Baja California, México, than in California, USA

Chlorinated hydrocarbons (CHs) were determined in blubber samples of 18 California sea lions (Zalophus californianus californianus) that stranded dead along Todos Santos Bay, Ensenada, Baja California, México, January 2000-November 2001. Summation operatorDDTs were the dominant group (geometric mean 3.8 microg/g lipid weight), followed by polychlorinated biphenyls ( summation operatorPCBs, 2.96 microg/g), chlordanes (0.12 microg/g) and hexachlorocyclohexanes (0.06 microg/g). The summation operatorDDTs/ summation operatorPCBs ratio was 1.3. We found CH levels more than one order of magnitude lower than those reported for California sea lion samples collected along the California coast, USA, during the same period as our study. This sharp north-south gradient suggests that Z. californianus stranded in Ensenada (most of them males) would probably have foraged during the summer near rookeries 500-1000 km south of Ensenada and the rest of the year migrate northwards, foraging along the Baja California peninsula, including Ensenada, and probably farther north.     

Presence of plutonium contamination in soils from Palomares (Spain)

More than 30 years after the occurrence of an aircraft accident which involved the detonation of two nuclear weapons in the surrounding area of the village of Palomares (Spain), the affected terrestrial area has been investigated for remaining transuranic contamination. Evidence from the presence of this contamination was initially found through the analysis of the 241Am inventories in superficial soil samples collected in the region, and was confirmed through the analysis of the (239+240)Pu inventories and their associated 238Pu/(239+240)Pu activity ratios in the same samples. However, it was also observed that a considerable fraction of the remaining contamination in the area was present in particulate form, i.e. as "hot particles". The work performed in our laboratory for identification, isolation and characterisation of these "hot particles" as well as some conclusions obtained from these analyses are outlined in this paper.     

Ecotoxicity, phytotoxicity and extractability of heavy metals from different stabilised sewage sludges

The presence of heavy metals in the sludges produced in wastewater treatment plants restricts their use for agricultural purposes. This study compares different types of sludges (aerobic, anaerobic, unstabilised and sludge from a waste stabilisation pond) in order to assess the extractability of heavy metals using simple extraction, water and DTPA. The stabilisation treatment undergone by the sludges influenced the heavy metals extractability. The least mineralised sludges (unstabilised and aerobic) showed higher metal extractability. The sewage sludges were subjected to chemical characterisation and toxicity testing (ecotoxicity and phytotoxicity assays) in absence of substrate, to provide a preliminary assessment of their suitability for land application. The ecotoxicity assays confirmed that no sludge constituted a hazardous waste. The sludge extracts had significant adverse effect on the germination index (GI) of barley (Hordeum vulgare L.) and cress (Lepidium sativum L.), a fact which indicates that some characteristics affected root growth.     

Presence of surfactants and their degradation intermediates in sediment cores and grabs from the Cadiz Bay area

The occurrence and distribution of the major surfactants--LAS, AES, APEOs and AEOs--and their degradation intermediates--SPCs, AP and APECs--in a marine-estuarine environment at Spain are presented. Results show that their concentration in surface sediments is clearly correlated with their usage and the existence of wastewater discharges. The degradation processes appear to lead to the formation of SPCs in the case of LAS, and to the shortening of the average ethoxylated chain length in the case of NPEOs, AEOs and AES. Vertical profiles for AEOs and AES are reported for the first time and present the highest values nearest the surface, followed by a sharp decrease with depth for all surfactants, as well as the appearance of degradation intermediates in deeper sedimentary layers. Shorter LAS homologues and SPCs tend to be present in pore water while strongly non-polar intermediates like NP are firmly attached to the sediments.