Environmental preferences of yellowfin tuna (Thunnus albacares) at the northern extent of its range

We used acoustic telemetry to examine the small-scale movement patterns of yellowfin tuna (Thunnus albacares) in the California Bight at the northern extent of their range. Oceanographic profiles of temperature, oxygen, currents and fluorometry were used to determine the relationship between movements and environmental features. Three yellowfin tuna (8 to 16 kg) were tracked for 2 to 3 d. All three fish spent the majority of their time above the thermocline (18 to 45 m in depth) in water temperatures >17.5 °C. In the California Bight, yellowfin tuna have a limited vertical distribution due to the restriction imposed by temperature. The three fish made periodic short dives below the thermocline (60 to 80 m), encountering cooler temperatures (>11 °C). When swimming in northern latitudes, the depth of the mixed layer largely defines the spatial distribution of yellowfin tuna within the water column. Yellowfin prefer to spend most of their time just above the top of the thermocline. Oxygen profiles indicated that the tunas encountered oceanic water masses that ranged most often from 6.8 to 8.6 mg O₂ l⁻¹, indicating no limitation due to oxygen concentrations. The yellowfin tuna traveled at speeds ranging from 0.46 to 0.90 m s⁻¹ (0.9 to 1.8 knots h⁻¹) and frequently exhibited an oscillatory diving pattern previously suggested to be a possible strategy for conserving energy during swimming. Received: 14 February 1997 / Accepted: 14 April 1997     

Metal availability and uptake by sorghum plants grown in soils amended with sludge from different treatments

Several factors depending on the sludge, the soil, or the combination of both substrates, may affect element availability to plants. In this study, an assessment was done of the effect of two sludges obtained by different processes (activated sludge and facultative stabilization pond) on heavy-metal availability and uptake by sorghum plants in soils with high and low copper contents. Results obtained for DTPA-extractable metal indicated higher metal availability in sludge-amended soils. In addition, sludges caused changes in copper and zinc distribution in soil, indicating in most cases a discrete increase in the more labile metal forms. However, observed changes did not increase heavy metal concentration in plant leaves, indicating that assessment of metal availability by a chemical procedure (single extraction or metal fractionation) would not permit a good prediction of metal bioavailability. On the other hand, sludge application at a rate of 100 t ha⁻¹ to high-copper agricultural soils would not imply greater mobility of this metal on account of a greater sorbing capacity provided by the sludges. Such results would indicate that sludges from wastewater treatment plants, meeting the standards of heavy metal contents, regardless of the process by which they were obtained, may be applied to several kinds of soil, even to high-copper soils, with no risk of increasing heavy metal bioavailability to phytotoxic levels in the short range.     

Study concerning the recovery of zinc and manganese from spent batteries by hydrometallurgical processes

Used batteries contain numerous metals in high concentrations and if not disposed of with proper care, they can negatively affect our environment. These metals represent 83% of all spent batteries and therefore it is important to recover metals such as Zn and Mn, and reuse them for the production of new batteries. The recovery of Zn and Mn from used batteries, in particular from Zn–C and alkaline ones has been researched using hydrometallurgical methods. After comminution and classification of elemental components, the electrode paste resulting from these processes was treated by chemical leaching. Prior to the leaching process the electrode paste has been subjected to two washing steps, in order to remove the potassium, which is an inconvenient element in this type of processes. To simultaneously extract Zn and Mn from this paste, the leaching method in alkaline medium (NaOH solution) and acid medium (sulphuric acid solution) was used. Also, to determine the efficiency of extraction of Zn and Mn from used batteries, the following variables were studied: reagents concentration, S/L ratio, temperature, time. The best results for extraction yield of Zn and Mn were obtained under acid leaching conditions (2 M H₂SO₄, 1 h, 80 °C).     

An experimental design for the optimization of the extraction methods of metallic mobile fractions from environmental solid samples

The evaluation of the cadmium and lead mobile forms from environmental solid samples provides information about their mobility and bioavailability. In the present study, the Cd and Pb mobile fractions were obtained by two modified extraction methods applied to industrial and acidic pH soils or to polluted sediments. In order to highlight that the extraction procedure does not significantly influence the quantitative atomic absorption spectrometric determination of cadmium and lead, the robustness of the extraction methods was evaluated and proven applying a Youden and Steiner factorial design. Within this experimental design, the shaking rate, the shaking time, and the solid/liquid extraction ratio were modified. The measurement uncertainty of the whole analytical procedure was assessed, the contribution of the factors involved in the extraction process being insignificant compared to the other uncertainty sources. The importance of the study is related to the fact that it proves the applicability in the routine laboratory practice of the modified extraction methods by increasing the extraction ratio following thorough optimization and robustness studies.     

An investigation impact of user’s positions in closed space over SAR in the head induced from mobile phone

The purpose of this work was to investigate the impact of user’s positions in close space over the variations of SAR distribution in human head induced from mobile phone under the worst case conditions. The “worst case” considered in this paper refers to conditions that include (1) a half-wavelength dipole antenna, placed near the model of human head—SAM phantom; (2) a vertically oriented dipole antenna, parallel to the side walls of closed space for maximum reflection; (3) metallic closed space acts as a resonant cavity; and (4) 360 randomly selected observation points. We also used a free space model for comparative purposes. The maximum 1- and 10-g average SAR and average SAR in whole-exposed object probability density function curves have been derived to illustrate the percentage of SAR values that have been induced inside SAM for different locations of user in the closed space. The obtained results show that in more than 86.7% of all investigated user’s positions in the metallic closed space, the induced maximum 1-g average SAR in user’s head is in the boundaries of ±10% of maximum 1-g average SAR, when the user use mobile phone in free space. This relationship keep still at maximum 10-g average SAR, where in 85.9% from all investigated user’s positions, SAR values are in boundaries of ±10% of maximum 10-g average SAR in free space. The results showed that closed space causes more significant changes on average SAR in whole-exposed object than maximal SAR values. When we estimated the average SAR in whole-exposed SAM in 85% from all investigated user’s position in closed space, the induced SAR is higher than SAR values in free space model. It can be noted that the highest obtained SAR values in closed space were with 8.5% (for 1 g), 6.7% (for 10-g average SAR), and 15.1% (for average SAR in whole SAM) higher than these of the free space.     

Spatio-temporal geostatistical modelling of sulphate concentration in the area of the Reocín Mine (Spain) as an indicator of water quality

Environmental Science and Pollution Research - Water stored in open-pit lakes can be a water resource when the mine is closed. This study aimed to develop a reliable model to evaluate the water...     

Distribution of pesticide residues in soil and uncertainty of sampling

Pesticide residues were determined in about 120 soil cores taken randomly from the top 15 cm layer of two sunflower fields about 30 days after preemergence herbicide treatments. Samples were extracted with acetone-ethyl acetate mixture and the residues were determined with GC-TSD. Residues of dimethenamid, pendimethalin, and prometryn ranged from 0.005 to 2.97 mg/kg. Their relative standard deviations (CV) were between 0.66 and 1.13. The relative frequency distributions of residues in soil cores were very similar to those observed in root and tuber vegetables grown in pesticide treated soils. Based on all available information, a typical CV of 1.00 was estimated for pesticide residues in primary soil samples (soil cores). The corresponding expectable relative uncertainty of sampling is 20% when composite samples of size 25 are taken. To obtain a reliable estimate of the average residues in the top 15 cm layer of soil of a field up to 8 independent replicate random samples should be taken. To obtain better estimate of the actual residue level of the sampled filed would be marginal if larger number of samples were taken.     

Atrazine degradation by fungal co-culture enzyme extracts under different soil conditions

This investigation was undertaken to determine the atrazine degradation by fungal enzyme extracts (FEEs) in a clay-loam soil microcosm contaminated at field application rate (5 μg g^?1) and to study the influence of different soil microcosm conditions, including the effect of soil sterilization, water holding capacity, soil pH and type of FEEs used in atrazine degradation through a 2⁴ factorial experimental design. The Trametes maxima–Paecilomyces carneus co-culture extract contained more laccase activity and hydrogen peroxide (H₂O₂) content (laccase = 18956.0 U mg protein^?1, H₂O₂ = 6.2 mg L^?1) than the T. maxima monoculture extract (laccase = 12866.7 U mg protein^?1, H₂O₂ = 4.0 mg L^?1). Both extracts were able to degrade atrazine at 100%; however, the T. maxima monoculture extract (0.32 h) achieved a lower half-degradation time than its co-culture with P. carneus (1.2 h). The FEE type (p = 0.03) and soil pH (p = 0.01) significantly affected atrazine degradation. The best degradation rate was achieved by the T. maxima monoculture extract in an acid soil (pH = 4.86). This study demonstrated that both the monoculture extracts of the native strain T. maxima and its co-culture with P. carneus can efficiently and quickly degrade atrazine in clay-loam soils.     

Deposition of dust with active substances in pesticides from treated seeds in adjacent fields during drilling: disentangling the effects of various factors using an 8-year field experiment

Environmental Science and Pollution Research - The side effects from the use of plant protection products and their potential effects on non-target arthropods (NTAs) such as honey bees, other...     

The interplay between exposure to PAHs and MTHFR C677T polymorphism on cardiovascular risk biomarkers in Mexican women

Environmental Science and Pollution Research - Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality worldwide. Environmental and genetic factors are recognized as risk...