Relation between mortality of young walleye (Stizostedion vitreum) and recruitment with different forms of compensation

The relation between mortality of young fish and recruitment is important for assessment of the environmental effects of facilities that kill large numbers of young fish, such as electric power stations and hydropower plants. A simulation model with a bioenergetic growth component was applied to examine the relation between mortality of young and recruitment for walleye (Stizostedion vitreum) with different forms of population regulation, including: food limited growth, food limited growth with size-dependent mortality, and food limited growth with age at maturity dependent on size. With food limited growth small increases in mortality of young reduced recruitment considerably, but the population slowly approached a new equilibrium. If mortality of young increased when growth was food limited, the population approached a new equilibrium of natality and mortality because with fewer individuals there was more food per individual, and individuals were larger in size and produced more eggs; this feedback adjusted natality to equal mortality. With either mortality or age at maturity dependent on size, large increases in mortality of young resulted in only small decreases in recruitment.     

Seasonal variations in nickel and vanadium in Mont Blanc snow and ice dated from the 1960s and 1990s

Ni and V have been determined in snow and ice collected at a high altitude location (Col du D?me) near the summit of Mont Blanc on the French-Italian border; dated from the 1960s and 1990s. Ni and V were simultaneously determined by inductively coupled plasma sector field mass spectrometry. Measured concentrations range from 6 to 700 pg g(-1) and 4 to 1,100 pg g(-1) for Ni and V, respectively. The results show pronounced seasonal variations in the concentrations of both metals, with high concentration values in summer layers and much lower values for winter layers. These seasonal variations are linked especially with the existence of inversion layers during winter months. Ni and V concentrations in excess of the contributions from rock and soil dust (Ni(excess), V(excess)) appear to be mainly associated with anthropogenic inputs, with pronounced seasonal variations. Large variations in the V(excess)/Ni(excess) ratio are observed, with a higher ratio in summer than in winter. This shows differences in anthropogenic inputs at Col du D?me during the different parts of the year. The above ratio was compared with the corresponding ratios for oil combustion from stationary sources and the exhaust from gasoline and diesel engines. It appears that Ni and V concentrations at Col du D?me are probably the result of changing combinations of contributions from oil combustion for power generation, industrial and residential uses, on one side, and automobile and truck traffic, on the other side, with possibly a significant contribution from Ni smelters in Russia during winter months.     

Evaluation of two adsorbents for diffusive sampling and thermal desorption-gas chromatographic analysis of monoterpenes in air

Tube type samplers with two different adsorbents, Chromosorb 106 and Tenax TA, were evaluated by laboratory experiments and field tests for simultaneous diffusive sampling of alpha-pinene, beta-pinene and delta 3-carene and subsequent thermal desorption-gas chromatographic analysis. No statistically significant effects of exposure time, concentrations of monoterpenes or relative humidity were found for samplers with Chromosorb 106 when running a factorial design, with the exception of the adsorption of delta 3-carene, for which some weak effects were noted. Samplers with Tenax TA were affected by the sampling time as well as the concentration for all terpenes, with a strong interaction effect between these two factors. The terpenes showed good storage stability on both adsorbents. No effect of back-diffusion was noted when using Chromosorb 106, while Tenax TA showed some back-diffusion effects. The uptake rates, in ml min-1, for the terpenes on Chromosorb 106 were 0.36 for alpha-pinene, 0.36 for beta-pinene and 0.40 for delta 3-carene. The corresponding average values on Tenax TA were 0.30 for alpha-pinene, 0.32 for beta-pinene and 0.38 for delta 3-carene. The field validation proved that diffusive sampling on Chromosorb 106 agreed well with pumped sampling on charcoal for stationary samples, while the personal samples indicated a discrepancy of 25% between Chromosorb 106 and charcoal samples. Tenax TA generally gave lower results than Chromosorb 106 in all field samples. Samplers packed with Chromosorb 106 could be used to monitor terpene levels in workplaces such as sawmills. The major advantages with this method are the sampling procedure, which is simple to perform compared to other techniques, the easily automated analysis procedure and the possibility to reuse the samplers.     

Prediction of zinc, cadmium, lead, and copper availability to wheat in contaminated soils using chemical speciation, diffusive gradients in thin films, extraction, and isotopic dilution techniques

To predict the availability of metals to plants, it is important to understand both solution- and solid-phase processes in the soil, including the kinetics of metal release from its binding agent (ligand and/or particle). The present study examined the speciation and availability of Zn, Cd, Pb, and Cu in a range of well-equilibrated metal-contaminated soils from diverse sources using several techniques as a basis for predicting metal uptake by plants. Wheat (Triticum aestivum L.) was grown in 13 metal-contaminated soils and metal tissue concentrations (Zn, Cd, Pb, and Cu) in plant shoots were compared with total soil metal concentrations, total soluble metal, and free metal activities (pM2+) in soil pore waters, 0.01 M CaCl2-extractable metal concentrations, E values measured by isotope dilution, and effective metal concentrations, C(E), measured by diffusive gradients in thin films (DGT). In the DGT technique, ions are dynamically removed by their diffusion through a gel to a binding resin, while E values represent the isotopically exchangeable (labile) metal pools. Free metal activities (Zn2+, Cd2+, and Pb2+) in soil pore waters were determined using a Donnan dialysis technique. Plant Zn and Cd concentrations were highly related to C(E), while relationships for Zn and Cd with respect to the other measures of metals in the soils were generally lower, except for CaCl2-extractable Cd. These results suggest that the kinetically labile solid-phase pool of metal, which is included in the DGT measurement, played an important role in Zn and Cd uptake by wheat along with the labile metal in soil solution. Plant Pb concentrations were highly related to both soil pore water concentrations and C(E), indicating that supply from the solid phase may not be so important for Pb. Predictions of Cu uptake by wheat from these soils by the various measures of Cu were generally poor, except surprisingly for total Cu.     

Metal Fractionation Studies in Surfacial and Core Sediments in the Achankovil River Basin in India

The Fractionation of Fe, Zn, Cu, Pb, Mn and Cd in the sediments of the Achankovil River, Western Ghats, India using a sequential extraction method was carried out to understand the metal availability in the basin for biotic and abiotic activities. Spatial distribution of heavy metals has been studied. Sediment grain size has significant control over the heavy metal distribution. The fluctuations in their concentration partly depend upon the lithology of the river basin and partly the anthropogenic activities. The sediments are dominated by sand and are moderately to strongly positively skewed and are very leptokurtotic in nature. The quartzite and feldspars are abundant minerals along with significant amount of mica with low clay content. The core sediments show increasing trend of heavy metal concentration with depth due to the recent addition of anthropogenic sources and post-diagenic activities. Significant amount of Cd (18%) was found in carbonate fraction, which may pose environmental problems due to its toxic nature. Small concentrations of metals, except Cd and Cu, are in exchangeable fraction, which indicate low bio-availability. Enrichment Factor (EF) for individual metals shows the contribution from terrregious and in part from anthropogenic sources. Selective Sequential Extraction (SSE) study shows the variation in specific metal distribution pattern, their distribution in different phases and their bio-availability. Maximum amount of the metals were bound to the non-residual fractions (mainly Fe-oxides). Overall, bio-availability of these micronutrients from sediments seems to be very less. Non-residual phase is the most important phase for majority of heavy metals studied. Among the non-residual fraction, maximum amount of the heavy metals bound to Fe-oxides. The study high lights the need for in-depth study of heavy metals distribution and fractionation in the smaller river basins to get precise information on the behavior and transport of heavy metals in the fluvial environment and their contribution to the world ocean.     

Arsenic exposure in Hungary, Romania and Slovakia

Inorganic arsenic is a potent human carcinogen and toxicant which people are exposed to mainly via drinking water and food. The objective of the present study was to assess current exposure to arsenic via drinking water in three European countries. For this purpose, 520 individuals from four Hungarian, two Slovakian and two Romanian countries were investigated by measuring inorganic arsenic and methylated arsenic metabolites in urine by high performance liquid chromatography with hydride generation and inductively coupled plasma mass spectrometry. Arsenic in drinking water was determined by atomic absorption spectrometry. Significantly higher concentrations of arsenic were found in both the water and the urine samples from the Hungarian counties (median: 11 and 15 microg dm(-3), respectively; p < 0.001) than from the Slovakian (median: 0.94 and 4.5 microg dm(-3), respectively) and Romanian (median: 0.70 and 2.1 microg dm(-3), respectively) counties. A significant correlation was seen between arsenic in water and arsenic in urine (R(2)= 0.46). At low water arsenic concentrations, the relative amount of dimethylarsinic acid (DMA) in urine was increased, indicating exposure via food. Also, high body mass index was associated with higher concentrations of arsenic in urine (p= 0.03), mostly in the form of DMA. Smokers had significantly higher urinary arsenic concentrations than non-smokers (p= 0.03). In conclusion, elevated arsenic exposure via drinking water was prevalent in some of the counties. Exposure to arsenic from food, mainly as DMA, and cigarette smoke, mainly as inorganic arsenic, are major determinants of arsenic exposure at very low concentrations of arsenic in drinking water.     

Thallium: a review of public health and environmental concerns

Thallium (Tl) is a rare but widely dispersed element. All forms of thallium are soluble enough to be toxic to living organisms. Thallium is more toxic to humans than mercury, cadmium, lead, copper or zinc and has been responsible for many accidental, occupational, deliberate, and therapeutic poisonings since its discovery in 1861. Its chemical behavior resembles the heavy metals (lead, gold and silver) on the one hand and the alkali metals (K, Rb, Cs) on the other. It occurs almost exclusively in natural waters as monovalent thallous cation. The solubility of thallous compounds is relatively high so that monovalent thallium is readily transported through aqueous routes into the environment. Tl can be transferred from soils to crops readily and accrues in food crops. The fascinating chemistry and high toxicity potential make thallium and its compounds of particular scientific interest and environmental concern. Thallium was detected in base-metal mining effluents. The conventional removal of heavy metals from wastewater has little effect on thallium. In this review, various treatment options and removal technologies are enumerated in order to protect the environment from thallium toxicity.     

Design and evaluation of an inlet conditioner to dry particles for real-time particle sizers

Real-time particle sizers provide rapid information about atmospheric particles, particularly peak exposures, which may be important in the development of adverse health outcomes. However, these instruments are subject to erroneous readings in high-humidity environments when compared with measurements from filter-based, federal reference method (FRM) samplers. Laboratory tests were conducted to evaluate the ability of three inlet conditioners to dry aerosol prior to entering a real-time particle sizer for measuring coarse aerosols (Model 3321 Aerodynamic Particle Sizer, APS) under simulated highly humid conditions. Two 30 day field studies in Birmingham, AL, USA were conducted to compare the response of two APSs operated with and without an inlet conditioner to that measured with FRM samplers. In field studies, the correlation of PM(10-2.5) derived from the APS and that measured with the FRM was substantially stronger with an inlet conditioner applied (r2 ranged from 0.91 to 0.99) than with no conditioner (r2 = 0.61). Laboratory experiments confirmed the ability of the heater and desiccant conditioner to remove particle-borne moisture. In field tests, water was found associated with particles across the sizing range of the APS (0.5 microm to 20 microm) when relative humidity was high in Birmingham. Certain types of inlet conditioners may substantially improve the correlation between particulate mass concentration derived from real-time particle sizers and filter-based samplers in humid conditions.     

Variations in PCB concentrations between genders of six warmwater fish species in Lake Logan Martin, Alabama, USA

We collected and analyzed 955 individual fish (six species) for sexual differences in PCB bioaccumulations from a southeastern, USA reservoir. Using 2-way ANCOVAs, we found significant differences in fillet PCB concentrations between sexes for channel catfish (Ictalurus punctatus), largemouth bass (Micropterus salmoides) and spotted bass (Micropterus punctulatus). Striped bass (Morone saxatilus), black crappie (Pomoxis nigromaculatus) and freshwater drum (Aplodinotus grunniens) did not display differences between sexes in PCB concentrations. We suspect that sexual differences may be due to biological differences in reproduction, relative motility and lipid deposition. For one species (striped bass), sexual differences in PCB concentrations were inconsistent with a study in the Hudson River suggesting that sexual differences in bioaccumulations can change across ecosystems. Two species which did show sexual differences, largemouth bass and channel catfish, are often chosen as representative species (e.g., "piscivore" and "benthivore") in contaminant monitoring in many USA states indicating human consumption and risk management decisions would be improved if an equal number of male and female fish were included in composite PCBs analysis. This could reduce variability in fish PCBs data from which consumption advisories are based.