In situ bioassays with Chironomus riparius larvae to biomonitor metal pollution in rivers and to evaluate the efficiency of restoration measures in mine areas

In this study we evaluate the ability of an in situ bioassay with Chironomus riparius larvae, using larval development and growth as endpoints, to biomonitor water quality and to assess the biological recovery of metal contaminated freshwater ecosystems of mine areas that are subject of restoration measures. The bioassay was carried out in streams located near an abandoned goldmine in North Portugal, throughout an environmental rehabilitation of the mine (2002-2004). During this period, a decrease in the inhibition of larval growth in the metal contaminated stream was observed. The bioassay was also performed in streams located near an active tungsten mine in Central Portugal. Larval growth and development were highly inhibited in the stream that receives acid drainage from the tungsten mine and treated water from the AMD treatment station. The results indicate that the bioassay can be used to evaluate the efficiency of environmental restoration measures in mining areas.     

Characterization of Atrazine-Loaded Biodegradable Poly(Hydroxybutyrate-Co-Hydroxyvalerate) Microspheres

Polyhydroxybutyrate-co-hydroxyvalerate microspheres (PHBV-MS) were prepared as a delivery system for the herbicide atrazine (ATZ). Characterization of the system included investigation of in vitro release properties and genotoxicity. ATZ − PHBV-MS particle diameters showed a size distribution range of 1–13 μm. Differential scanning calorimetry analyses indicated that ATZ was associated with the PHBV microparticles. The release profiles showed a different release behavior for the pure herbicide in solution, as compared with that containing ATZ-loaded PHBV-MS. Korsmeyer–Peppas model analyses showed that atrazine release from the microparticles occurred by a combination of diffusion through the matrix and partial diffusion through water-filled pores of the PHBV microparticles. A Lactuca sativa test result showed that the genotoxicity of ATZ-loaded PHBV-MP was decreased in relation to ATZ alone. The results demonstrate a viable biodegradable herbicide release system using atrazine for agrochemical purposes.     

Influence of humified organic matter on copper behavior in acid polluted soils

The main purpose of this work was to identify the role of soil humic acids (HAs) in controlling the behavior of Cu(II) in vineyard soils by exploring the relationship between the chemical and binding properties of HA fractions and those of soil as a whole. The study was conducted on soils with a sandy loam texture, pH 4.3-5.0, a carbon content of 12.4-41.0 g kg⁻¹ and Cu concentrations from 11 to 666 mg kg⁻¹. The metal complexing capacity of HA extracts obtained from the soils ranged from 0.69 to 1.02 mol kg⁻¹, and the stability constants for the metal ion-HA complexes formed, log K, from 5.07 to 5.36. Organic matter-quality related characteristics had little influence on Cu adsorption in acid soils, especially if compared with pH, the degree of Cu saturation and the amount of soil organic matter.     

Environmental performance and spillover effects on productivity: evidence from horticultural firms

This study investigates the effect of environmental investment and related spillover effects on productivity in the agricultural sector by using a panel data of horticultural firms in Andalusia (Southern Spain). The results indicate a positive relationship between firm investment in environmental practices and productivity improvement, also showing the presence of positive environmental spillovers. In a second-stage of analysis, the incidence of environmental factors in firm specific individual technical efficiency is estimated. This analysis also shows the link between environmental knowledge diffusion and horticultural firms' performance.     

Natural materials for treatment of industrial effluents: comparative study of the retention of Cd, Zn and Co by calcite and hydroxyapatite. Part I: batch experiments

This work explores the heavy metal retention capacity of materials developed from minerals that are abundant in nature, with low cost and minimum environmental impact. To accomplish this objective we have: (a) characterized commercial samples of calcite (CA) and hydroxyapatite (HAP)--including their surface properties (BET area, electrophoretic mobility, SEM, and X-ray energy dispersive spectroscopy); and, (b) qualified and quantified the interaction of Cd, Zn and Co with calcite (CaCO3) and hydroxyapatite [Ca5(PO4)3OH] through batch experiments, in a range of metal concentrations (4Zn>Co and Cd>Zn approximately Co, respectively. Retention increased with pCa and pH and could be modeled by: (a) a non-ideal ion exchange mechanism (Me/Ca) for the adsorption of Cd, Zn and Co onto CA; and, (b) a mechanism of non-ideal ion exchange and specific adsorption (Me/Ca and identical with PO4O-Me) in the case of HAP. The pH dependence is indirect in CA and is related to its solubility changes (pCa increases with pH, and so does sorption of Cd, Zn and Co). Both materials, HAP and CA, can be used for heavy metal retention. The former has better performance for water treatment due to its greater efficiency for the retention of Cd, Zn and Co (over two orders of magnitude per gram of material) and its lower solubility in a wide range of pH (6相似文献   

Effects of some environmental parameters on catalase activity measured in the mussel (Mytilus galloprovincialis) exposed to lindane

Mussels (Mytilus galloprovincialis), collected from the Bizerta lagoon, were acclimated for four days to various conditions of temperature, salinity, photoperiod and food supply and then exposed to lindane at a concentration of 40 microg l(-1). Catalase activity, which is a biomarker of exposure to an oxidative stress, was measured in the whole soft tissues of control and assay groups. In control mussels, high temperature, high salinity and light duration significantly increased catalase activity whereas this activity decreased when food, composed of freeze-dried, algae was available. When mussels were treated with lindane, catalase activities were higher than in controls. This increase was significant with temperature, salinity and light duration. The food supply did not change catalase activity, which was always higher compared to controls. Oxidative stress was shown in mussels exposed to lindane. The results highlight the need of considering abiotic parameters in biomonitoring studies, and especially when using catalase as a biomarker.     

Human health risk assessment case study: an abandoned metal smelter site in Poland

United States Environmental Protection Agency methodologies for human health risk assessment (HRA) were applied in a Brownfields Demonstration Project on the Warynski smelter site (WSS), an abandoned industrial site at Piekary Slaskie town, Upper Silesia, Poland. The HRA included the baseline risk assessment (BRA) and the development of risk-based preliminary remedial goals (RBPRGs). The HRA focused on surface area covered with waste materials, which were evaluated with regard to the potential risks they may pose to humans. Cadmium, copper, iron, manganese, lead, and zinc were proposed as the contaminants of potential concern (COPCs) at WSS based on archive data on chemical composition of waste located on WSS. For the defined future land use patterns, the industrial (I) and recreational (II) exposure scenarios were assumed and evaluated. The combined hazard index for all COPCs was 3.1E+00 for Scenario I and 3.2E+00 for Scenario II. Regarding potential carcinogenic risks associated with the inhalation route, only cadmium was a contributor, with risks of 1.6E-06 and 2.6E-07 for Scenario I and Scenario II, respectively. The results of the BRA indicated that the potential health risks at WSS were mainly associated with waste material exposure to cadmium (industrial and recreational scenarios) and lead (industrial scenario). RBPRGs calculated under the industrial scenario were 1.17E+03 and 1.62E+03 mg/kg for cadmium and lead, respectively. The RBPRG for cadmium was 1.18E+03 mg/kg under the recreational scenario. The BRA results, as well as RBCs, are comparable for both scenarios, so it is impossible to prioritize land use patterns for WSS based on these results. For choosing a future land use pattern or an appropriate redevelopment option, different factors would be decisive in the decision-making process, e.g., social, market needs, technical feasibility and costs of redevelopment actions or acceptance of local community.     

Use of the light absorption coefficient to monitor elemental carbon and PM2.5--example of Santiago de Chile

The optical absorption coefficient, particulate matter with an aerodynamic diameter <2.5 microm, and elemental carbon (EC) have been measured simultaneously during winter and spring of 2000 in the western part of Santiago, Chile (Pudahuel district). The optical measurements were carried out with a low-cost instrument recently developed at the University of Santiago. From the data, a site-specific mass absorption coefficient of 4.45+/-0.01 m2/g has been found for EC. In addition, a mass absorption coefficient of 1.02+/-0.03 m2/g has been obtained for PM2.5. These coefficients can be used during the colder months (May-August) to obtain EC concentration or PM2.5 from a measurement of the light absorption coefficient (sigmaa). The high correlation that has been found between these variables indicates that sigmaa is a good indicator of the degree of contamination of urbanized areas. The data also show an increase in PM2.5 and EC concentration during winter and an increase in the ratio of EC to PM2.5. When the EC/PM2.5 ratio is calculated during rush hour (7:00 a.m.-11:00 a.m.) and during part of the night (9:00 p.m.-2:00 a.m.), it is found that the increase is caused by higher concentration levels of EC at night. These results suggest that the rise in the EC concentration is caused by emissions from heating and air mass transport of pollution from other parts of the city, while traffic contribution remains approximately constant.     

Modelling the effects of eutrophication, mitigation measures and an extreme flood event on estuarine benthic food webs

Human-mediated and natural disturbances such as nutrient enrichment, habitat modification, and flood events often result in significant shifts in species composition and abundance that translate into changes in the food web structure. Six mass-balanced models were developed using the “Ecopath with Ecosim” software package to assess changes in benthic food web properties in the Mondego estuarine ecosystem (Portugal). Field, laboratory and literature information were used to construct the models. The main study objective was to assess at 2 sites (a Zostera meadow and a bare sediment area) the effects of: (1) a period of anthropogenic enrichment, which led to excessive production of organic matter in the form of algal blooms (1993/1994); (2) the implementation of mitigation measures, following a long period of eutrophication (1999/2000); and (3) a centenary flood (winter 2000/2001). Different numbers of compartments were identified at each site and in each time period. In general, the Zostera site, due to its complex community, showed a higher number of compartments and a higher level of system activity (i.e. sum of consumptions, respiration, flow to detritus, production, total system throughput, net primary production and system omnivory index). The differences at the two sites in the three time periods in the breakdown of throughput were mainly due to differences in the biomass of the primary producers (higher primary production at the Zostera site). Consumption, respiration and flow to detritus were dominated by the grazers Hydrobia ulvae and Scrobicularia plana at the Zostera and bare sediment sites respectively. At both sites, after recovery measures were implemented there was an increase in S. plana and Hediste diversicolor biomass, consumption, respiration and flows to detritus, and a decrease in H. ulvae biomass and associated flows, which increased again after the flood event. The mass-balanced models showed that the trophic structure of the benthic communities in Mondego estuary was affected differently by each disturbance event. Interestingly, in our study a high system throughput seems to be associated with higher stress levels, which contradicts the idea that higher system activity is always a sign of healthier conditions.     

Soil remediation time to achieve clean-up goals I: Influence of soil water content

The current models are not simple enough to allow a quick estimation of the remediation time. This work reports the development of an easy and relatively rapid procedure for the forecasting of the remediation time using vapour extraction. Sandy soils contaminated with cyclohexane and prepared with different water contents were studied. The remediation times estimated through the mathematical fitting of experimental results were compared with those of real soils. The main objectives were: (i) to predict, through a simple mathematical fitting, the remediation time of soils with water contents different from those used in the experiments; (ii) to analyse the influence of soil water content on the: (ii(1)) remediation time; (ii(2)) remediation efficiency; and (ii(3)) distribution of contaminants in the different phases present into the soil matrix after the remediation process. For sandy soils with negligible contents of clay and natural organic matter, artificially contaminated with cyclohexane before vapour extraction, it was concluded that (i) if the soil water content belonged to the range considered in the experiments with the prepared soils, then the remediation time of real soils of similar characteristics could be successfully predicted, with relative differences not higher than 10%, through a simple mathematical fitting of experimental results; (ii) increasing soil water content from 0% to 6% had the following consequences: (ii(1)) increased remediation time (1.8-4.9h, respectively); (ii(2)) decreased remediation efficiency (99-97%, respectively); and (ii(3)) decreased the amount of contaminant adsorbed onto the soil and in the non-aqueous liquid phase, thus increasing the amount of contaminant in the aqueous and gaseous phases.