RECOVERY: A Contaminated Sediment-Water Interaction Model

This paper describes the U.S. Army Corps of Engineers screening-level water quality model (RECOVERY version 3.0) for assessing long-term impacts of contaminated bottom sediments on surface waters. The model couples contaminant interaction between the water column and the bottom sediment, as well as between contaminated and clean bottom sediments. The analysis is intended primarily for organic contaminants with the assumption that the overlying water column is well mixed vertically. The contaminant is assumed to follow linear, reversible, equilibrium sorption and first-order decay kinetics. The system is physically represented as a well-mixed water column (i.e., zero-dimensional) underlain by a vertically-stratified sediment column (i.e., one-dimensional). The sediment is well-mixed horizontally but segmented vertically into a well-mixed surface (active) layer and deep sediment. The deep sediment is segmented into variably contaminated and clean sediment regions. Processes incorporated in the model are sorption, decay, volatilization, burial, resuspension, settling, bioturbation, and pore-water diffusion. The solution couples contaminant mass balance in the water column and in the mixed sediment layer along with diffusion in the deep sediment layers. The model was verified against laboratory and field data, as well as against an analytical solution for the water and mixed sediment layers. These comparisons indicate that the model can be used as an assessment tool for evaluating remediation alternatives for contaminated bottom sediments.     

Direct and indirect generation of waste in the Spanish paper industry

The paper industry has a relatively high degree of reliance on suppliers when compared to other industries. Exploring the role of the paper industry in terms of consumption of intermediate inputs from other industries may help to understand how the production of paper does not only generate waste by itself but also affects the amount of waste generated by other industries. The product Life Cycle Assessment (LCA) is a useful analytical tool to examine and assess environmental impacts over the entire life cycle of a product “from cradle to grave” but it is costly and time intensive. In contrast, Economic Input Output Life Cycle Assessment Models (IO-LCA) that combine LCA with Input–Output analysis (IO) are more accurate and less expensive, as they employ publicly available data. This paper represents one of the first Spanish studies aimed at estimating the waste generated in the production of paper by applying IO-LCA. One of the major benefits is the derivation of the contribution of direct and indirect suppliers to the paper industry. The results obtained show that there was no direct relationship between the impact on output and the impact on waste generation exerted by the paper industry. The major contributors to waste generation were the mining industry and the forestry industry.     

Larval development rate predicts range expansion of an introduced crab

Introduced populations can cause ecological and economic damage and are difficult to eradicate once they have established. It is therefore important to be able to predict both where species may become established and their capacity to spread within recipient regions. Here, we use a new method to assess potential for intraregional spread of a marine crab introduced to North America, Carcinus maenas. We determined survivorship and development rates throughout a range of temperatures in the laboratory for C. maenas larvae from non-native populations on the Atlantic and Pacific coasts of North America. The larvae exhibited narrower physiological tolerances than adults, and no lab-cultured larvae completed larval development below 10.0°C or above 22.5°C. Survivorship peaked at intermediate water temperatures of 12.5–20.0°C, and development time decreased with increasing temperatures within this range. Based upon these laboratory development rates, we used nearshore sea-surface temperature data from both coasts of North America to predict development times required for larvae at different months and sites. Taken together, survivorship and development data indicate that C. maenas has the capacity to continue its northward spread and establish populations at numerous additional sites in North America. Moreover, decadal temperature data at two Alaskan sites predicted little variability in development duration across years, suggesting that development duration predictions are robust to interannual water temperature differences.     

Comparison of basal cytotoxicity of seven carbamates in CHO-K1 cells

The cytotoxic effects of seven carbamate pesticides, aldicarb, aldicarb sulfone, aldicarb sulfoxide, benfuracarb, pirimicarb, propoxur and thiobencarb, were compared in Chinese hamster ovary (CHO-K1) cell line of Circetulus griseus. The endpoints evaluated were lysosomal function by neutral red assay and mitochondrial integrity by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT assay). The carbamates tested were evaluated in both serum-free medium and in serum-containing medium. Results demonstrate that CHO-K1 lysosomes appeared more susceptible to propoxur, aldicarb and its metabolites than mitochondria. Aldicarb was the most toxic carbamate pesticide tested on CHO-K1 cells and aldicarb sulfoxide the least. The presence of foetal calf serum (FCS) diminished significantly the cytotoxicity of tested carbamates.     

Optimization of anaerobic processes by speciation and bioavailability of trace metals

The deficiency trials of some trace metals (copper, nickel, zinc) were made in laboratory Upflow Anaerobic Sludge Blanket (UASB) reactors containing the inoculum of an industrial anaerobic sludge, a basal medium with the rest of nutrients and vitamins in comparison with a control reactor with the optimal doses of trace elements. From the main control parameters (alkalinity, acidity, DQO), no inactivation by deficit of essential elements was detected, but the control reactor showed greater mineralization and solid content, being necessary to make purge to avoid bulking. The inoculum has high metallic element contents, so the additional contribution produces high bacterial growth, also purge being necessary to avoid bulking. The purge, made after 120 days in continuous operation, eliminates a great quantity of solids and increases the volatile solids (VS)/total solids (TS) ratio. The comparison of the initial content of metallic elements in the solid and liquid phases with the contents after 120 days showed a progressive depletion of metals in all reactors without a clear appreciation of the lack of the studied metals. Finally, in 210 days, the reactors without addition of a metallic element accumulated greater quantity of major (Ca, Fe, Mg) and trace (Co, Ni, Cu) elements in the solid phase with respect to the control.     

Pollution profiles and physicochemical parameters in old uncontrolled landfills

The long-term effectiveness of the geological barrier beneath municipal-waste landfills is a critical issue for soil and groundwater protection. This study examines natural clayey soils directly in contact with the waste deposited in three landfills over 12 years old in Spain. Several physicochemical and geological parameters were measured as a function of depth. Electrical conductivity (EC), water-soluble organic carbon (WSOC), Cl⁻, NH₄⁺, Na⁺ and exchangeable NH₄⁺ and Na⁺ were used as parameters to measure the penetration of landfill leachate pollution. Mineralogy, specific surface area and cationic-exchange capacities were analyzed to characterize the materials under the landfills. A principal component analysis, combined with a Varimax rotation, was applied to the data to determine patterns of association between samples and variables not evident upon initial inspection. The main factors explaining the variation in the data are related to waste composition and local geology. Although leachates have been in contact with clays for long time periods (13-24 years), WSOC and EC fronts are attenuated at depths of 0.2-1.5 m within the clay layer. Taking into account this depth of the clayey materials, these natural substrata (>45% illite-smectite-type sheet silicates) are suitable for confining leachate pollution and for complying with European legislation. This paper outlines the relevant differences in the clayey materials of the three landfills in which a diffusive flux attenuation capacity (A_c) is defined as a function (1) of the rate of decrease of the parameters per meter of material, (2) of the age and area of the landfill and (3) of the quantity and quality of the wastes.     

Homing in the wolf spider Lycosa tarantula (Araneae, Lycosidae): the role of active locomotion and visual landmarks

Previous studies on the homing of the wolf spider Lycosa tarantula have shown that it is carried out by path integration. Animals using this mechanism must measure the distance walked and the angles turned. This study aims to understand if wolf spider L. tarantula is able to estimate the walked distance in an outward path. As this information is more likely obtained by proprioceptive mechanisms, active or passive displacements have been performed. An active locomotion was found essential to estimate distances. During passive locomotion, spiders searched for their burrows near the release point while when displaced actively the inbound journey was longer than the outbound one. The possible use of visual landmarks near the burrow was also tested as a cue to complete the inbound journey. Our results did not show that L. tarantula used these visual landmarks to find the burrow. L. tarantula seems to use only proprioceptive information obtained during the outbound path to estimate the distance traveled.     

Platanus pollen season in Andalusia (southern Spain): trends and modeling

Platanus is a major cause of pollen allergy in many Spanish cities. The present paper reports an analysis of Platanus pollen season throughout the Andalusia region (southern Spain), which has among the highest pollen counts and the highest incidence of Platanus-related allergies in Europe. The main aim was to analyze pollen season trends from 1992 to 2010 in Andalusia; models were also constructed to forecast the start of the season. Daily pollen counts were recorded using Hirst-type volumetric spore-traps. Pollen season start-dates were very similar at all sites, usually occurring in March. The pollen season was delayed over the study period. The Pollen-season duration and Pollen index generally increased throughout the study period. The starting date for temperature accumulation was around the 10th February, although the threshold temperatures varied by site. The regional model for Andalusia failed to provide sufficiently accurate results compared with sub-regional or local models. For modeling purposes, three sub-regions are recommended: Inland, East Coast and West Coast.     

Liquid discharges from the use of radionuclides in medicine (diagnosis)

The production and discharge of liquid radioactive wastes as excreta from patients undergoing Nuclear Medicine Diagnostic (NMD) in a hospital were studied. Instantaneous and accumulated activity, discharged from the hospital to the sewage system, has been estimated keeping in mind radionuclide decay. This study would enable estimation of the environmental impact due to NMD procedures. Annual accumulated activities of 2.2GBq ((131)I), 1.847GBq ((99m)Tc), 0.743GBq ((123)I), 0.337GBq ((67)Ga), 0.169GBq ((111)In) and 0.033GBq ((201)Tl) result from our model when applied to a European hospital. A comparison is made with calculations by other authors that do not consider the radionuclide decay and who overestimate by two orders of magnitude. Doses to critical people as sewage treatment workers are also significantly reduced. So, our results stress the importance of including the decay in the calculations.