Chromium (VI) Retrieval from Chromium Ore Processing Residues by Electrokinetic Treatment

Electrokinetics (EK) was investigated as a possible technique for in-situ treatment of leachable chromium at a built site contaminated with chromium ore processing residues (COPR). A preliminary EK experiment was carried out at the laboratory scale on an undisturbed COPR core sample. Methods applied for material and pore water characterization before and after EK treatment addressed physical aspects by laser diffraction granulometry, pycnometry and pore water content, mineralogical aspects by X-ray diffraction, scanning electron microscopy coupled with energy dispersive X-ray spectroscopy, and chemical aspects by inductively coupled plasma-atomic emission spectroscopy and atomic absorption spectroscopy for elemental composition, spectrophotometry for Cr(VI) analysis, and potentiometry for pH determination. EK was run at 1 V/cm with no external constraints on current intensity. The EK experiment reached an extraction of 72% of the total leachable Cr(VI) after only 10 days of treatment and 84% after 20 days. Material texture, composition, and pH remained similar. These results indicate that EK presents a potential solution for extracting leachable Cr(VI) from COPR sites. The impounded COPR material appeared to be heterogeneous in composition at all scales, from field to lab sample, adding to the challenge of in-situ treatment.     

Design,Synthesis and Evaluation of New Marine Alkaloid-Derived Pentacyclic Structures with Anti-Tumoral Potency

This work describes the synthesis and biological evaluation of a new heterocyclic hybrid derived from the ellipticine and the marine alkaloid makaluvamine A. Pyridoquinoxalinedione 12 was obtained in seven steps with 6.5% overall yield. 12 and its intermediates 1–11 were evaluated for their in vitro cytotoxic activity against different cancer cell lines and tested for their inhibitory activity against the human DNA topoisomerase II. The analysis by electrophoresis shows that the pentacycle 12 inhibits the topoisomerase II like doxorubicine at 100 µM. Compound 9 was found to have an interesting profile, having a cytotoxicity of 15, 15, 15 and 10 μM against Caco-2, HCT-116, Pc-3 and NCI cell lines respectively, without any noticeable toxicity against human fibroblast.     

Soil organic carbon–stock changes in Flemish grassland soils from 1990 to 2000

Total soil organic‐carbon (SOC) stocks for grassland soils in Flanders (N Belgium) were determined for the Kyoto Protocol reference year 1990 and 2000 in order to investigate whether these soils have been CO₂ sinks or sources during that period. The stocks were calculated by means of detailed SOC datasets, which were available at the community scale for the whole of Flanders. The total SOC stocks for Flemish grassland soils (1 m depth) were estimated at 38 Mt SOC in 1990 and 34 Mt SOC in 2000. The loss of SOC resulted from a decrease in the SOC content of grassland soils (71%) and could also partly (29%) be explained by a decline in grassland area. Significant decreases in %SOC for the 0–6 cm depth layer were found for the 1990s for the coarser‐textured soils with SOC losses ranging between –0.3% and –0.5% over the 10 y period. Specific management practices that disturb the SOC balance such as conversion to temporary grassland and a reduction of animal‐manure application are hypothesized to have contributed to the observed loss of SOC stocks. We furthermore conducted an analysis of uncertainty of the 1990 and 2000 grassland SOC–stocks calculation using Monte Carlo analysis. Probability‐distribution functions were determined for each of the inputs of the SOC‐stock calculation, enabling us to assess the uncertainty on the 1990 and 2000 SOC stocks. The frequency distributions of these simulated stocks both closely approached lognormal distributions, and their 95%‐confidence intervals ranged between 150% and 50% of the calculated mean SOC stock. The standard error on the measured decrease in SOC stocks in Flemish grassland soils during the 1990s was calculated to be 7–8 Tg SOC, which is equivalent to twice this decrease. This clearly shows that large‐scale changes in SOC stocks are uncertainty‐ridden, even when they are based on detailed datasets.     

Biotic and abiotic drivers of intraspecific trait variation within plant populations of three herbaceous plant species along a latitudinal gradient

Background

The importance of intraspecific trait variation (ITV) is increasingly acknowledged among plant ecologists. However, our understanding of what drives ITV between individual plants (ITV_BI) at the population level is still limited. Contrasting theoretical hypotheses state that ITV_BI can be either suppressed (stress-reduced plasticity hypothesis) or enhanced (stress-induced variability hypothesis) under high abiotic stress. Similarly, other hypotheses predict either suppressed (niche packing hypothesis) or enhanced ITV_BI (individual variation hypothesis) under high niche packing in species rich communities. In this study we assess the relative effects of both abiotic and biotic niche effects on ITV_BI of four functional traits (leaf area, specific leaf area, plant height and seed mass), for three herbaceous plant species across a 2300 km long gradient in Europe. The study species were the slow colonizing Anemone nemorosa, a species with intermediate colonization rates, Milium effusum, and the fast colonizing, non-native Impatiens glandulifera.

Results

Climatic stress consistently increased ITV_BI across species and traits. Soil nutrient stress, on the other hand, reduced ITV_BI for A. nemorosa and I. glandulifera, but had a reversed effect for M. effusum. We furthermore observed a reversed effect of high niche packing on ITV_BI for the fast colonizing non-native I. glandulifera (increased ITV_BI), as compared to the slow colonizing native A. nemorosa and M. effusum (reduced ITV_BI). Additionally, ITV_BI in the fast colonizing species tended to be highest for the vegetative traits plant height and leaf area, but lowest for the measured generative trait seed mass.

Conclusions

This study shows that stress can both reduce and increase ITV_BI, seemingly supporting both the stress-reduced plasticity and stress-induced variability hypotheses. Similarly, niche packing effects on ITV_BI supported both the niche packing hypothesis and the individual variation hypothesis. These results clearly illustrates the importance of simultaneously evaluating both abiotic and biotic factors on ITV_BI. This study adds to the growing realization that within-population trait variation should not be ignored and can provide valuable ecological insights.

     

Application of Humic Substances Results in Consistent Increases in Crop Yield and Nutrient Uptake

The effect of humic substances on yield and nutrient uptake of grass, maize, potato and spinach was investigated in six field experiments and two pot experiments in a high input cropping system. The humic substances originating from leonardite formations in Canada were applied as liquid solution to the soil (Humifirst liquid) or as a solid incorporated in mineral fertilizers (Humifirst incorporated). Formal meta-analysis of the results of all executed experiments showed that the application of humic substances had an overall positive effect on dry matter yield of the crops and this effect was statistically significant for Humifirst incorporated. In the case of permanent grassland, humic substances promoted mainly the production of the first grass cut, which has the highest grass quality among all cuts during the growing season. Tuber production on the potato field trial showed a high response on the application of humic substances. Total potato yield increased with 13 and 17% for Humifirst liquid and Humifirst incorporated, respectively. The effect of humic substances on maize yield was limited, probably due to the rather high nutrient status of both soils. Finally, the formal meta-analysis showed a consequent increase in nitrogen and phosphorus uptake of all studied crops as well. The effect on potassium and magnesium uptake was also mainly positive, while sodium and calcium uptake were not affected in most of the experiments.     

Streptococcus suis type 2 infections in pigs in the Netherlands (Part two)

Since 1983 some pig breeding and fattening farms in the Netherlands have been faced with a considerable mortality in pigs due to Streptococcus suis type 2 infections. The most predominant clinical feature of S. suis type 2 infection is meningitis, although sudden deaths often occur. It was noted that some affected farms had imported breeding stock from the United Kingdom. Tonsils of slaughter pigs were collected from herds with and without a history of S. suis type 2 infections. Bacteriological examination was done by using an elective-selective medium. No significant difference was found in carrier rates of S. suis type 2 between clinically healthy and affected herds (38% vs. 45%). A cohort study was carried out by regular bacteriological examination of tonsil biopsies on a farm with a high incidence of streptococcal meningitis. Twenty-seven percent of the pigs were carriers of S. suis type 2 at nine weeks of age. Possible methods for disease control are discussed.     

Biochemical markers of bone metabolism and risk of dorsal metacarpal disease in 2-year-old Thoroughbreds

REASONS FOR PERFORMING STUDY: Dorsal metacarpal disease (DMD) is a common problem in 2-year-old racehorses and results in loss of a significant number of days from training. Biochemical markers of bone cell activity measured early in the training season could have value for identifying 2-year-old Thoroughbred racehorses that develop DMD. OBJECTIVES: To determine the association between serum concentrations of osteocalcin, the carboxyterminal propeptide of type I collagen (PICP) and the carboxyterminal cross-linked telopeptide of type I collagen (ICTP) measured early in the training season and the risk of DMD. METHODS: Blood samples were collected from 165 two-year-old Thoroughbreds during late November/early December. Osteocalcin and PICP were measured as markers of bone formation, and ICTP as a marker of bone resorption. Training and veterinary records for each horse were monitored over the following training/racing season (10 months). Cases were defined as an episode where signs of DMD were sufficiently severe for a horse to miss at least 5 consecutive days of training. Classification tree and logistic regression analysis were used to identify the most important factors suitable for prediction of DMD risk. RESULTS: There were 24 cases of DMD during the season (14.6% cumulative incidence), with an average time to recognition of approximately 6 months (May). The earliest recognised case was in February and the latest in September. Osteocalcin and ICTP concentrations in the early stages of the training season were significantly higher in horses that subsequently developed DMD (P = 0.017 and 0.019, respectively). DMD cases were also significantly older compared to noncases (21.04 vs. 20.44 months, P = 0.023). Using a multivariable logistic regression model, it was possible to postulate a set of diagnostic rules to predict the likelihood of DMD injury during the season. This suggested that horses with ICTP concentrations above 12365 ug/l and older than 20.5 months are 2.6 times more likely to develop DMD. CONCLUSIONS: The measurement of the bone resorption marker ICTP could be useful for identification of 2-year-olds at increased risk of developing DMD. POTENTIAL RELEVANCE: These findings, together with other strategies such as modification of training regimens, e.g. early introduction of short distances of high-speed exercise into the training programme, could help reduce the days lost to training as a result of DMD.     

Linking macrodetritivore distribution to desiccation resistance in small forest fragments embedded in agricultural landscapes in Europe

Purpose

Most of the agricultural landscape in Europe, and elsewhere, consists of mosaics with scattered fragments of semi-natural habitat like small forest fragments. Mutual interactions between forest fragments and agricultural areas influence ecosystem processes such as nutrient cycling, a process strongly mediated by the macrodetritivore community, which is however, poorly studied. We investigated macrodetritivore distribution patterns at local and landscape-level and used a key functional trait (desiccation resistance) to gain mechanistic insights of the putative drivers.

Methods

Macrodetritivores were sampled in forest edges-centres of 224 European forest fragments across 14 landscapes opposing in land use intensity. We used a multilevel analysis of variance to assess the relative contribution of different spatial scales in explaining activity-density and Shannon-diversity of woodlice and millipedes, together with a model-based analysis of the multivariate activity-density data testing the effect on species composition. Secondly, we tested if desiccation resistance of macrodetritivores varied across communities at different spatial scales using linear mixed effect models.

Results

Forest edge-centre and landscape use intensity determined activity-density and community composition of macrodetritivores in forest fragments, while fragment characteristics like size and continuity were relatively unimportant. Forest edges and higher intensity landscapes supported higher activity-density of macrodetritivores and determined species composition. Forest edges sustained woodlouse communities dominated by more drought tolerant species.

Conclusions

Landscape use intensity and forest edges are main drivers in macrodetritivore distribution in forest fragments with desiccation resistance a good predictor of macrodetritivore distribution. Key functional traits can help us to predict changes in community structure in changing landscapes.