Respiration rates of Chiloplacus sp. and other arctic nematodes at low and high temperatures

Summary Respiration of an undescribed species of soil nematode of the genus Chiloplacus from the Canadian High Arctic was measured at 2°, 5°, 10°, 15°, 20° and 25°C. The corresponding metabolic rates were 0.2697×10^-3 l, 0.3406×10^-3 l, 0.8408×10^-3 l, 0.8539×10^-3 l, 1.8420×10^-3 l and 2.9360×10^-3 l O₂ ind^-1 h^-1, respectively, for a nematode of 1.0 g dry weight. The relationship between respiration and dry weight for Chiloplacus sp. at 10°C is described by the function log R=-3.0693+0.8844 log W. Q₁₀ values for the 2°–5°, 5°–10°, 10°–15°, 15°–20° and 20°–25°C temperature intervals were 2.18, 6.09, 1.03, 4.65 and 2.54, respectively. Chiloplacus sp. showed raised metabolic rates at low tempetatures compared with species from warmer environments. Metabolic rates of representative samples of the soil, nematode fauna (dominated by individuals of the genus Plectus) from the same location were 0.1593×10^-3 l, 0.3603×10^-3 l and 0.5332×10^-3 l O₂ ind^-1 h^-1 at 5°, 10° and 15°C for an average nematode of 0.4297 g dry weight.     

Increased taxane accumulation in callus cultures of Taxus cuspidata and Taxus × media by some elicitors and precursors

In Taxus cuspidata callus, vanadyl sulfate (10 mg l^–1) induced a high (146 g g^–1 dry wt) production of 10-deacetylbaccatin III in comparison to 7 g g^–1 dry wt of the control. The content of paclitaxel in this species increased from 16 g g^–1 to 74 g g^–1 dry wt when 20 mg phenylalanine l^–1 was used. In T. media, p-aminobenzoic acid induced the highest content of 10-deacetylbaccatin III (481 g g^–1 dry wt) versus 181 g g^–1 in the control. Paclitaxel increased from 89 to 139 g g^–1 dry wt after adding chitosan (20 mg l^–1) to the cultures.     

Initiation and culture of potato tuber callus tissue with picloram

Callus cultures of 7 potato cultivars were initiated from tuber tissue and maintained on Gelrite-solidified media with 1–20 M picloram as the only PGR. Ten M picloram was the optimal concentration for callus induction. By 4–6 weeks after explanting, there was sufficient callus produced for subculture to maintenance media which contained 1–20 M picloram as the only PGR. When grown in the dark at 25°C, subcultured callus typically increased 10-fold in wet weight in 4–5 weeks. The callus produced was friable and a light grey to cream color. Callus cultures were used to establish cell suspension cultures. Callus and cell suspension cultures have been maintained for over 2 years on the picloram containing media.Abbreviations BA benzyladenine - 2,4-D 2,4-dichlorophenoxyacetic acid - MS Murashige-Skoog - NAA naphthaleneacetic acid - PGR plant growth regulator Research paper #9053 of the Idaho Agricultural Experiment Station.     

Influence of nitrogen on the behaviour of nickel in wheat

A glasshouse experiment was conducted to study the effect of Ni on the growth and nutrients concentration in wheat (Triticum aestivum Cv. WH 291) in the presence and absence of applied N as urea. Responses to N application were observed up to 120 g N g^–1 soil. No response to Ni was observed in the dry matter yield of wheat tops (leaves + stem) in the absence of applied N while in the presence of applied N, significant yield increases were obtained at 12.5g Ni g^–1 soil. Nickel was not toxic to wheat up to 50g Ni g^–1 soil in the presence of 120g N g^–1 soil. Nitrogen and Ni concentration in wheat tops and roots increased with increasing levels of applied N and Ni, respectively. Applied Ni had an antagonistic effect on N concentration. Similarly, N reduced the Ni concentration in the wheat tissues. Positive growth responses to Ni were associated with 22 and 15g Ni g^–1 in wheat tops, in the presence of applied N at 60 and 120g N g^–1 soil, while Ni toxicity was associated with 63, 92.5 and 112.5g Ni g^–1 in wheat tops, in the absence and presence of applied N at 60 and 120g N g^–1 soil, respectively.     

Adventitious shoot formation and plant regeneration from tissues of tomatillo (Physalis ixocarpa Brot.)

Cultured hypocotyl explants of tomatillo (Physalis ixocarpa Brot.), were evaluated with regard to their morphogenic responses to combinations of benzyladenine (BA, 0–5 M) with either naphthaleneacetic acid (NAA, 0–50 M) or 2,4-dichlorophenoxyacetic acid (2,4-D, 0–50 M). The induction of shoots or roots was dependent on the cytokinin/auxin combination.Hypocotyl explants failed to form shoots when they were grown on media containing either a cytokinin or an auxin alone. The highest frequency of shoot formation was observed on media containing 12.5–25 M BA and 5 M NAA. Likewise the highest frequency of root formation was observed on media supplemented with 1 M BA and 1 M NAA. Complete plants were regenerated and transferred to soil, where they reached maturity.     

The contribution of size-fractionated plankton to biomass and primary production of phytoplankton in saline–alkaline ponds

Primary productivity, biomass and chlorophyll-a of size fractionated phytoplankton (<0.22 m, <3 m, <8 m, <10 m, <40 m, <64 m, <112 m and <200 m) were estimated in 6 ponds and 5 experimental enclosures. The results showed that the planktonic algae less than 10 m are important in the biomass and production of phytoplankton in saline–alkaline ponds. The production of size fractionated phytoplankton corresponding to <112 m, <10 m and <3 m in saline–alkaline ponds were 10.5 ± 6.6 , 8.6 ± 5.4 and 0.33 ± 0.1 mgC l^–1 d^–1, respectively. Mean community respiration rate was 1.80 ± 0.73, 1.69 ± 0.90 and 1.38 ± 1.12 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) were 1.61, 8.30 and 0.33 mgC l^–1 d^–1, respectively. The ratio of those to the total phytoplankton production was 15%, 79% and 3%, respectively. The mean respiration rate of the different size groups was 0.11, 0.31 and 1.38 mgC l^–1 d^–1; the ratio of those to total respiration of phytoplankton was 6%, 17% and 77%, respectively. The production of size-fractionated phytoplankton corresponding to <200 m, <10 m and <3 m in enclosures was 2.19 ± 1.63, 2.08 ± 1.75 and 0.22 ± 0.08 mgC l^–1 d^-1, respectively. Mean community respiration rates were 1.25 ± 1.55, 1.17 ± 1.42 and 0.47 ± 0.32 mgC l^–1 d^–1, respectively. The average production of phytoplankton corresponding to micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton was 0.11, 1.86 and 0.22 mgC l^–1 d^–1, respectively. The ratio of those to the total production of phytoplankton was 5%, 85% and 10%, respectively. The mean respiration rate of different size groups were 0.08, 0.72 and 0.46 mgC l^–1 d^–1, the ratio of those to total respiration of phytoplankton was 6%, 57% and 37%, respectively. The concentrations of chlorophyll-a of the phytoplankton in the corresponding size of micro- (10–112 m), nano- (3–10 m) and pico- (<3 m) plankton in the experimental ponds were 19.3, 98.2 and 11. 9 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 15%, 76% and 9%, respectively. The concentrations of chlorophyll-a of phytoplankton micro- (10–200 m), nano- (3–10 m) and pico- (<3 m) plankton in enclosures were 1.7, 34.3 and 3.0 g l^–1, respectively. The ratio of those to the total chlorophyll-a was 4%, 88% and 8%, respectively.     

Development of an L6 myoblast in vitro model of moniliformin toxicosis

L6 myoblasts were used as an in vitro model to investigate the role of moniliformin and its interaction with monensin in turkey knockdown syndrome and sudden death syndromes in poultry. Cell viability and microscopic and ultrastructural alterations noted in L6 myoblasts cultured in the presence of moniliformin (0.0–0.3 g/l) were compared to those observed in parallel cultures also containing one of the following compounds: selenium (0–0.004 ng/l), thiamine (0–0.3 g/l), or pyruvate (0–0.46 g/l). Marked dilation of the RER, membranous whorls, glycogen deposition, membrane-bound cytoplasmic inclusions and necrosis were observed in myoblasts exposed to 0.03/2-0.30 g moniliformin/l medium. Supplementation of medium with thiamine and pyruvate, or selenium, provided significant protection to cells exposed to 0.0–0.3 g/l or 0.0–0.15 g moniliformin/l, respectively. Dose-dependent differences in protein and ATP production were not detected. Myoblasts grown in medium containing 0–0.15 g moniliformin/l and 7.5–50.0 M A23187, beauvericin or monensin had degrees of cytotoxicity similar to parallel cultures receiving only an ionophore. L6 myoblasts were a useful model of moniliformin toxicosis. The findings of this study suggest cytotoxicity due to moniliformin in L6 myoblasts may be due in part to oxidative damage and altered pyruvate metabolism, and that moniliformin does not predispose myoblasts to ionophore toxicosis. This study supports the results of in vivo investigations in poultry that moniliformin and monensin do not act synergistically to induce knockdown or monensin toxicosis.     

Product inhibition during the feeding phasein fed-batch ethanol fermentation of sugar-cane blackstrap molasses

Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: = ₀ - k · E and v = v ₀ · K/(K +E) Nomenclature E ethanol concentration in the aqueous phase of the fermenting medium (g.L^–1) - E_m value of E when = 0 or = 0 (g.L^–1) - F medium feeding rate (L.h^–1) - k empirical constant (L.g^–1.h^–1) - K empirical constant (g.L^–1) - M_as mass of TRS added to the, reactor (g) - M_cs mass of consumed TRS (g) - M_e mass of ethanol in the aqueous phase of the fermenting medium (g) - M_s mass of TRS in the aqueous phase of the fermenting medium (g) - M_x mass of yeast cells (dry matter) in the fermenting medium (g) - r correlation coefficient - S TRS concentration in the aqueous phase of the fermenting medium (g.L^–1) - S_m TRS concentration of the feeding medium (g.L^–1) - t time (h) - T temperature (° C) - TRS total reducing sugars calculated as glucose - V volume of the fermenting medium (L) - V₀ volume of the inoculum (L) - X yeast cells concentration (dry matter) in the fermenting medium (g.L^–1) - filling-up time (h) - specific growth rate of the yeast cells (h^–1) - ₀ value of when E=0 - specific production rate of ethanol (h^–1) - ₀ value of when E=0 - density of the yeast cells (g.L^–1) - dry matter content of the yeast cells     

Photoautotrophic micropropagation of Russet Burbank Potato

The photoautotrophic micropropagation of potato cv. Russet Burbank was investigated. Single node microcuttings were grown for four weeks on Murashige and Skoog (MS) medium with or without sucrose (30 g l^–1) in the growth room at 21/19 °C day/night temperature, with 16-h photoperiod at 150 mol m^–2 s^–1, with or without supplemental CO₂ at 1500 l l^–1. A 20% increase in the number of nodes per stem (from 7.5 to 9.4) and a 50% increase in stem dry weight were observed in cultures grown on media with sucrose and in CO₂ enriched atmosphere comparing to the conventionally micropropagated cultures or the cultures grown photoautotrophically on media without sucrose but in air supplemented with 1500 l l^–1CO₂. Stems of these cultures (from media with sucrose in CO₂ enriched air) almost doubled in length the stems of cultures from the other two treatments. No significant differences were observed between Control (MS medium supplemented with sucrose, 30 g l^–1) and photoautotrophic cultures coming from MS medium with no sucrose grown under 1500 l l^–1 of CO₂. Photoautotrophic cultures produced stems averaging 43.3 mm, with 7 nodes and weighing 9.2 mg (dry weight), similar to conventionally grown in vitro cultures (47.9 mm with 7.5 nodes, 9.7 mg dry weight). Growers may consider photoautotrophic culturing of potato in areas where the high sterility levels are difficult to maintain. Supplementing air in the growth room with 1500 l l^–1 of CO₂ could be beneficial for potato plantlet production even on media containing sucrose since it significantly improved quality, size and biomass of produced plantlets, speeding up the multiplication.     

Arsenic concentrations in water and fish from Chautauqua Lake,New York

Synopsis Arsenic persists in Chautauqua Lake, New York waters 13 years after cessation of herbicide (sodium arsenite) application and continues to cycle within the lake. Arsenic concentrations in lake water ranged from 22.4–114.81 g l^–1, = 49.0 ag l^–1. Well water samples generally contained less than 10 g l^–1 arsenic. Arsenic concentrations in lake water exceeded U.S. Public Health Service recommended maximum concentrations (10 g l^–1) and many samples exceeded the maximum permissible limit (50 g l^–1). Fish accumulated arsenic from water but did not magnify it. Fish to water arsenic ratios ranged from 0.4–41.6. Black crappie (Pomoxis nigromaculatus) contained the highest arsenic concentrations (0.14–2.04 g g^–1 ), X = 0.7 g g^–1) while perch (Perca flavescens), muskellunge (Esox masquinongy) and largemouth bass (Micropterus salmoides) contained the lowest concentrations (0.02–0.13 g g^–1). Arsenic concentrations in fish do not appear to pose a health hazard for human consumers.     

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. (Apicomplexa: Eimeriidae) from the black-capped bulbul,Pycnonotus xanthopygos

Oocysts of Isospora ernsti n. sp. and Isospora blagburni n. sp. are described from the black-capped bulbul Pycnonotus xanthopygos from Lincoln Park Zoo, Chicago, Illinois. The bird came from southwestern Africa seven years earlier. I. ernsti oocysts are ellipsoidal to bluntly ovoid, 28–38 × 23–31m (mean 34 × 28 m) and have a single-layered oocyst wall. Micropyle, oocyst residuum and polar granules are absent. Sporocysts are elongate ovoid, 24–30 × 11–16 m (mean 27×13 m). Stieda and substiedal bodies and sporocyst residuum are present. I. blagburni oocysts are spherical to subspherical. 21–28 × 19–26 m (mean 25 × 23 m) and have a single oocyst wall. Sporocysts are ovoid and 17–23 × 10–13 m (mean 20 × 12 m). Stieda and substiedal bodies and sporocyst residuum are present.     

Growth inhibition of biomass adapted to the degradation of toluene and xylenes in mixture in a batch reactor with substrates supplied by pulses

A biomass adapted to degrade toluene and xylenes in mixture was grown in a batch reactor with substrates supplied by pulses. The inhibition of biomass growth in the course of substrate degradation was investigated. The maximal biomass concentration of 7 g l^–1 was obtained using 150 l of toluene and 15 l of a mixture of xylenes in one litre of liquid medium, and the maximal biomass productivity and yield were 53 mg l^–1 h^–1 and 0.32 g_DW g _s ^–1 , respectively. Higher quantities of substrate added by pulses, that is 200 l of toluene with 20 l of xylenes and 300 l of toluene with 30 l of xylenes, caused an accumulation of metabolites. These higher quantities of substrates caused inhibition of microbial growth. Among the metabolites produced, 4-methyl catechol was found in large quantities in the culture medium and in the cells.     

High frequency of bulblet regeneration from bulb scale sections of Fritillaria thunbergii

Fritillaria thunbergii Miq. bulb-scale sections were cultured using Murashige and Skoog (MS) medium supplemented with NAA (1.62 M) and KN/2iP/BA (0.47–23.23 M).A high frequency of bulblets was developed from the scale sections and these bulblets have developed leaves and roots in 12 weeks of culture. An optimum of 13.7 bulblets developed from scale sections on solid MS medium supplemented with 1.62 M NAA and 4.65 M KN. Cultures incubated under cycles of 16 h white fluorescent light (40 mol m^–2 s^–1) and 8 h dark at a temperature regime of 25°C have produced optimal bulblets compared to cultures incubated under continuous dark at 25°C. The bulblets were harvested at the end of culture period and were given cold treatment at 5°C for 5 weeks and then transplanted to a potting mixture of peat moss, vermiculite and perlite (1:1:1). The bulblets, which were more than 10 mm in diameter, sprouted (100%) in 5 weeks of transplantation.     

Menthol tolerant clones of Mentha arvensis: approach for in vitro selection of menthol rich genotypes

In vitro raised shoots of Mentha arvensis L. were screened for menthol tolerance level by growing them in media containing 0–100 g ml^–1 menthol. A total of 2850 regenerated shoots were step wise screened for menthol tolerance at the concentrations of 50 g ml^–1 followed by 60 and 70 g ml^–1. In this screening, only 30 individual regenerated shoots were able to survive. The clones from the primary screen were inoculated into rooting medium and, after rooting, transferred to pots in the greenhouse. Ultimately, these 30 menthol tolerant clones were multiplied and grown in the field in replicated plots of 2.5×2.5 m sizes. Twigs of 30 clones from the replicated trials were rechecked for tolerant phenotypes at a concentration of 70 g ml^–1 menthol wherein, these survived even after 7 days (secondary screening). These clones were checked for oil and menthol content and were found to be better than the control plants. Out of these 30 plants, five tolerated 80 g ml^–1 menthol (tertiary level screening) and were found to contain the highest amount of menthol per g leaf biomass. Molecular analysis through RAPD showed distinct variation in the profiles of these five plants, in comparison to the control. Using this method the relationship between the primer OPT 04, menthol tolerance and high menthol content character of the genotype was established. Further, a cultivar `Saksham' was released from the selections by CIMAP for superior performance.     

Effects of Tebuthiuron on aquatic productivity

Tebuthiuron (N-[5-(1,1-dimethylethyl)-1,3,4-thiadiazol-2-yl]-N,N-dimethylurea) appears to control the riparian shrub saltcedar (Tamarix spp.); however, its use is restricted since the fate and effects of this herbicide in aquatic systems are unknown. Possible tebuthiuron impacts on aquatic production were examined in ten 2846-1 three-phase, open-system mesocosms. Each mesocosm contained sediment, water, algae, micro- and macroinvertebrates and fish, and was open to the atmosphere for gas exchange and colonization by indigenous macroinvertebrates and algae. The following nominal doses of tebuthiuron were used: 0 (control), 10, 70, 200, 500, and 1000 g 1^–1. The 200 g 1^–1 dose approximated the highest concentration of tebuthiuron detected in a water body after experimental application to a watershed. Data generated from all treatment levels were used in tebuthiuron fate analysis and in correlation analysis between the mesocosm variables. The control and the 200 g 1^–1 treatment level were replicated (n = 3) to allow for additional statistical analyses of treatment effects at the 200 g 1^–1 level. The adsorption of tebuthiuron to sediments contained in ten mesocosms was described by the Freundlich equation, x/m = 3.24c^0.68. Phytoplankton primary production, chironomid density, and chironomid biomass were negatively correlated with tebuthiuron concentration during peak system productivity. Conversely, no trends were observed at any sample date between an omnivorous fish species and herbicide concentration. At the 200 g 1^–1 dose level, only chironomid density was reduced. Factors responsible for reductions in chironomid density may include 1) a species shift in the 200 g 1^–1 treatment algal assemblages toward a greater percentage of unpalatable biomass, and 2) decreased algal productivity and/or an algal species shift in mesocosms receiving dose levels greater than 200 g 1^–1. Chironomid density reduction at the 200 g 1^–1 dose level suggests that deleterious effects may occur in some stream systems exposed to a 200 g 1^–1 tebuthiuron concentration.Contribution No. T-9-367 of the College of Agricultural Sciences, Texas Tech University.Contribution No. T-9-367 of the College of Agricultural Sciences, Texas Tech University.     

Seasonal changes in inorganic and organic phosphorus in the soil of a riparian forest

This study addresses the temporal distribution of forms of phosphorus in the soil of a temporarily flooded riparian forest of the valley of the river Garonne (Southwest of France). A sequential extraction for forms of phosphorus of increasing chemical stability was used. During the study period (13 months), the forest was flooded a few days during March and May. In winter, resin-Pi concentration was high (26 g g^–1) in comparison to spring values (<9 g g^–1). NaHCO₃-Po, NaHCO₃-Pi or NaOH-Pi concentrations increased during winter (up to 74, 124 and 78 g g^–1 respectively) and decreased significantly during spring (32, 44 and 32 g g^–1 respectively). This pattern was attributed to simultaneous mineralization and plant uptake during the growing season and to the flood events (erosional processes and P-release). During summer and fall, resin-Pi concentration increased significantly (up to 26 g g^–1 in October). NaHCO₃-Po concentrations remained low during spring and summer (<33 g g^–1), and increased significantly in fall (>45 g g^–1 NaHCO₃-Pi or NaOH-Pi increased in late spring or summer (90 g g^–1 and 68 g g^–1 respectively). Increasing concentrations of the labile forms during late spring or summer were ascribed to the warm temperature and soil dryness that limited plant growth. HCl-Pi increased regularly after the floods (174 g g^–1 before the flood events to 254 g g^–1 after the floods). Residual P presented a similar pattern i.e. 214 g g^–1 and 279 g g^–1 respectively before and after the flood events. This pattern was attributed to a progressive incorporation of flood deposits to the soil.     

Pesticides and heavy metals in Danish streambed sediment

The role of streambed sediment as a sink for pesticides and heavy metals was investigated in 30 Danish lowland streams. The investigated streams drain catchments varying in hydrology, topography, soil type and land use. The <250 m newly accumulated fraction of the uppermost 1–2 cm layer of streambed sediment was analysed for 19 old and modern pesticides and 9 heavy metals. DDE was present in the sediment of all the streams. Of the herbicides, fungicides and insecticides currently in use, the most frequently detected was diuron (50.0%), fenpropimorph (66.7%) and lambda-cyhalothrin (6.7%), respectively. The pesticides detected in the highest concentration were fenpropimorph (1700 ng g^–1), propiconazole (130 ng g^–1) and isoproturon (110 ng g^–1). The heavy metals are listed in order of increasing median concentration: Cd (0.80 g g^–1), Co (9.1 g g^–1), As (12.0 g g^–1), Ni (19.0 g g^–1), Cr (19.2 g g^–1), Pb (19.7 g g^–1), Cu (20.1 g g^–1), V (28.5 g g^–1), Zn (103 g g^–1). The average number of pesticides detected in the 27 streams draining predominantly agricultural catchments was (3.7±2.0) being higher (p=0.077) than in the three streams draining non-agricultural catchments (1.7±0.6). Pesticides were significantly related to catchment size, soil type and hydrological regime. Several heavy metals (Cr, Cu, Pb, V and Zn) were related to urban activity and soil type.     

In vitro culture of Aloe Barbadensis Mill.: Micropropagation from vegetative meristems

A method for rapid and highly effective plant micropropagation from vegetative meristems was established for Aloe barbadensis Mill. Plant micropropagation was achieved culturing apices on medium containing 1.1 M 2,4-dichlorophenoxyacetic acid and 2.3 M kinetin for 15–30 days. High morphogenetic ability was maintained by transferring explants (after 60 days) on media containing 0.11 M 2,4-dichlorophenoxyacetic acid and 2.2 M 6-benzylaminopurine.     

The distribution and abundance of krill faecal material and oval pellets in the Scotia and Weddell Seas (Antarctica) and their role in particle flux

Summary The abundance and depth distribution of zooplankton faeces in spring to early summer were investigated along meridional transects (47°W and 49°W) that extended from the Scotia Sea (57°S) across the Weddell-Scotia Confluence and into the Weddell Gyre (62°S). The sea ice edge retreated from 59°30S to 61°S during the study. Faeces were sampled with nets, Niskin bottles and sediment traps and subsequently analysed by light and electron (SEM) microscopy. Krill faecal strings and oval faecal pellets of unknown origin were by far the most important zooplankton faeces and highest concentrations were always found in the Confluence often close to the ice border. Krill faeces were usually more abundant in the uppermost layer (0–50m) where they contributed an average of 130 g dry weight m^–3. There was an exponential decrease with depth, with a minimum of 0.6 g dry weight m^–3 in the 500–1000 m stratum. Oval pellets were more evenly distributed in the upper 1000 m of the water column, with an average of 9 g dry weight m ^–3, although there was a small peak (20 g dry weight m^–3) in the subsurface layer (50–150 m depth). Consecutive collections (day-night) of krill faeces using drifting sediment traps showed that only the larger strings sank from 50 to 150 m depth. Peritrophic membranes appeared to deteriorate during sinking. Diatoms (in particular Nitzschia and Thalassiosira spp.) contributed by far the bulk of material in krill and oval faeces. In samples collected near or under the pack ice, remains of crustaceans in both krill- and oval faeces were also found.Data presented here were collected during the European Polarstern Study (EPOS) sponsored by the European Science Foundation     

Mercury budget of an upland-peatland watershed

Inputs, outputs, and pool sizes oftotal mercury (Hg) were measured in a forested 10 hawatershed consisting of a 7 ha hardwood-dominatedupland surrounding a 3 ha conifer-dominatedpeatland. Hydrologic inputs via throughfall andstemflow, 13±0.4 g m^–2 yr^–1over the entire watershed, were about doubleprecipitation inputs in the open and weresignificantly higher in the peatland than in theupland (19.6 vs. 9.8 g m^–2 yr^–1). Inputs of Hg via litterfall were 12.3±0.7g m^–2 yr^–1, not different in thepeatland and upland (11.7 vs. 12.5 g m^–2yr^–1). Hydrologic outputs via streamflow were2.8±0.3 g m^–2 yr^–1 and thecontribution from the peatland was higher despiteits smaller area. The sum of Hg inputs were lessthan that in the overstory trees, 33±3 gm^–2 above-ground, and much less than eitherthat in the upland soil, 5250±520 gm^–2, or in the peat, 3900±100 gm^–2 in the upper 50 cm. The annual flux of Hgmeasured in streamflow and the calculated annualaccumulation in the peatland are consistent withvalues reported by others. A sink for Hg of about20 g m^–2 yr^–1 apparently exists inthe upland, and could be due to either or bothstorage in the soil or volatilization.