Lack of population genetic structuring in the marine planktonic diatom Pseudo-nitzschia pungens (Bacillariophyceae) in a heterogeneous area in the Southern Bight of the North Sea

Several marine holoplanktonic organisms show a high degree of geographically structured diversity for which it often remains unclear to what extent this differentiation is due to the presence of cryptic taxa. For the genetically distinct diatom Pseudo-nitzschia pungens var. pungens, we used six microsatellite markers to investigate the spatial and temporal genetic composition in the heterogeneous Southern Bight of the North Sea. Although our sampling area (ca. 100 km) comprised water bodies with different environmental conditions (marine, estuary, saline lake) and different degrees of connectivity (from complete isolation to supposedly free exchange between environments), no evidence of genetic differentiation was found. Expanding our sampling area (ca. 650 km), suggested a homogenous population structure over even larger areas in the North Sea. Our results suggest that the population structure of this diatom is mainly shaped by strong homogenizing effects of gene flow preventing genetic drift, even in water bodies with limited connectivity. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Estimating soil carbon turnover using radiocarbon data: A case-study for European Russia

Turnover rates of soil carbon for 20 soil types typical for a 3.7 million km² area of European Russia were estimated based on ¹⁴C data. The rates are corrected for bomb radiocarbon which strongly affects the topsoil ¹⁴C balance. The approach is applied for carbon stored in the organic and mineral layers of the upper 1 m of the soil profile. The turnover rates of carbon in the upper 20 cm are relatively high for forest soils (0.16–0.78% year⁻¹), intermediate for tundra soils (0.25% year⁻¹), and low for grassland soils (0.02–0.08% year⁻¹) with the exception of southern Chernozems (0.32% year⁻¹). In the soil layer of 20–100 cm depth, the turnover rates were much lower for all soil types (0.01–0.06% year⁻¹) except for peat bog soils of the southern taiga (0.14% year⁻¹). Combined with a map of soil type distribution and a dataset of several hundred soil carbon profiles, the method provides annual fluxes for the slowest components of soil carbon assuming that the latter is in equilibrium with climate and vegetation cover. The estimated carbon flux from the soil is highest for forest soils (12–147 gC/(m² year)), intermediate for tundra soils (33 gC/(m² year)), and lowest for grassland soils (1–26 gC/(m² year)). The approach does not distinguish active and recalcitrant carbon fractions and this explains the low turnover rates in the top layer. Since changes in soil types will follow changes in climate and land cover, we suggest that pedogenesis is an important factor influencing the future dynamics of soil carbon fluxes. Up to now, both the effect of soil type changes and the clear evidence from ¹⁴C measurements that most soil organic carbon has a millennial time scale, are basically neglected in the global carbon cycle models used for projections of atmospheric CO₂ in 21st century and beyond.     

Historical processes constrain patterns in global diatom diversity

There is a long-standing belief that microbial organisms have unlimited dispersal capabilities, are therefore ubiquitous, and show weak or absent latitudinal diversity gradients. In contrast, using a global freshwater diatom data set, we show that latitudinal gradients in local and regional genus richness are present and highly asymmetric between both hemispheres. Patterns in regional richness are explained by the degree of isolation of lake districts, while the number of locally coexisting diatom genera is highly constrained by the size of the regional diatom pool, habitat availability, and the connectivity between habitats within lake districts. At regional to global scales, historical factors explain significantly more of the observed geographic patterns in genus richness than do contemporary environmental conditions. Together, these results stress the importance of dispersal and migration in structuring diatom communities at regional to global scales. Our results are consistent with predictions from the theory of island biogeography and metacommunity concepts and likely underlie the strong provinciality and endemism observed in the relatively isolated diatom floras in the Southern Hemisphere.     

Tolerance and metabolism of phenol and chloroderivatives by hairy root cultures of Daucus carota L

Hairy root cultures are shown to be suitable experimental systems to screen higher plants for tolerance to various inorganic and organic pollutants, and for determining the role of the root matrix in the uptake and further metabolism of contaminants. A number of clones were obtained by infection of carrot tissues with Agrobacterium rhizogenes and two (the fastest and the slowest growing root clones) were chosen for further experimentation. Both clones showed a similar degree of tolerance towards phenol and its chlorinated derivatives, i.e. the growth of root biomass was maintained in concentrations of phenol equivalent to 1000 micromol/l, whilst the chlorophenols were tolerated only at concentrations 20 times lower (50 micromol/l). Transformed carrot roots were able to remove more than 90% of the exogenous phenolic compounds from the culture medium within 120 h after treatment. Metabolism of these compounds occurred in the root tissue and was accompanied by an increase in peroxidase activity.     

A comparison of swine wastewater treatment using real-time and fixed-time two-stage sequencing batch reactors

This study compared the swine wastewater treatment of two identical lab-scale two-stage sequencing batch reactors (TSSBR) under similar conditions except that one was operated on a fixed-time mode and the other on a real-time mode. While both TSSBR systems performed very well, the real-time TSSBR performed far better then the fixed-time TSSBR, in every aspect of carbon, nitrogen, and phosphorous removal. The removals of COD, TOC, were at 97% and for BOD5 even at 99.7%. In terms of NH4-N and TKN removals, the real-time TSSBR achieved removal of over 98%. For phosphorus removals (Ortho-P and total P) the results from the real-time TSSBR was quite remarkable at 97.7%.     

Benefits of sustainable waste management in the vegetable greenhouse industry

This study investigated the benefits of an on-site sustainable solid waste treatment and utilization system for the greenhouse industry. The composts made from greenhouse wastes were tested and found to contain high nutrient values and good physical properties, and could be used as high quality growing media. The finished composts were tested in a greenhouse against the conventional growth media (sawdust) and resulted in a 10% yield increase by using the compost. An economic analysis was conducted to show the economic benefits of on-site composting for a greenhouse operation. Based on a four-hectare tomato or pepper greenhouse, and amortizing the capital equipment over five years, the net annual cost of composting represents a savings of dollars 8,000 annually.     

Aeolian contributions of trace metals to marine sediments of Kuwait

Concentrations of silver, cadmium, chromium, iron, manganese, nickel, lead, vanadium, and zinc were determined in dust fallout samples from eight inland locations in Kuwait. Results were used to calculate enrichment factors for metals relative to their abundance in the continental crust using Fe as the conservative element. Five metals (Cu, Cr, Mn, Ni, and V) showed enrichment factors that were approximately unity (1.3–4.7). Higher enrichment factors for the rest (24–421) suggested an anthropogenic contribution for Ag, Cd, Pb, and Zn. However, all metals in dust fallout (except Pb and Zn) showed a degree of enrichment relative to unpolluted marine sediments that was approximately unity, suggesting a substantial aeolian contribution to trace metals in marine surface sediments. Higher enrichments for Pb and Zn probably reflect a larger input from local pollution sources. This is particularly true for lead, the enrichment of which showed a stronger association with the distribution of urban population. Probable contributions of aeolian transport to a band of elevated lead concentrations in marine surface sediments are discussed.     

Calculation of clothing insulation by serial and parallel methods: effects on clothing choice by IREQ and thermal responses in the cold.

Cold protective clothing was studied in 2 European Union projects. The objectives were (a) to examine different insulation calculation methods as measured on a manikin (serial or parallel), for the prediction of cold stress (IREQ); (b) to consider the effects of cold protective clothing on metabolic rate; (c) to evaluate the movement and wind correction of clothing insulation values. Tests were carried out on 8 subjects. The results showed the possibility of incorporating the effect of increases in metabolic rate values due to thick cold protective clothing into the IREQ model. Using the higher thermal insulation value from the serial method in the IREQ prediction, would lead to unacceptable cooling of the users. Thus, only the parallel insulation calculation method in EN 342:2004 should be used. The wind and motion correction equation (No. 2) gave realistic values for total resultant insulation; dynamic testing according to EN 342:2004 may be omitted.     

Effect of Starch Granule Size on Viscosity of Starch-Filled Poly(hydroxy ester ether) Composites

The effect of starch granule size on the viscosity of starch-filled poly(hydroxy ester ether) (PHEE) composites was characterized using size-fractionated potato starch, as well as unfractionated starches (rice, corn, wheat, and potato). Potato starch was separated using an air classifier into four particle size fractions: <18 m, 18-24 m, 24-30 m, and >30 m. The starch was dried to a moisture content of 0.5% to minimize moisture effects on composite rheology. PHEE and potato starch were extruded with starch volume fractions of 0.46 and 0.66. Stress relaxation, frequency and strain sweep, and temperature-dependence measurements were carried out. Although small variations in viscosity were seen with the different potato starch fractions, differences were not significant at a volume fraction of 0.46. Viscosity differences between the different particle size fractions were more pronounced at a volume fraction of 0.66. The temperature dependence could be described by an Arrhenius relation, with an apparent activation energy of 84 kJ/mole. At a volume fraction of 0.46, the starch/PHEE viscosities increased in the order potato starch < wheat starch corn starch < rice starch.