Synthesis and evaluation of lipophilic BTBP ligands for An/Ln separation in nuclear waste treatment: the effect of alkyl substitution on extraction properties and implications for ligand design

Four new 6,6′-bis(1,2,4-triazin-3-yl)-2,2′-bipyridine (BTBP) ligands, which contain either additional alkyl groups on the pyridine rings or seven-membered aliphatic rings attached to the triazine rings, have been synthesized, and the effects of the additional alkyl substitution in the 4- and 4′-positions of the pyridine rings on their extraction properties with LnIII and AnIII cations in simulated nuclear waste solutions have been studied. The speciation of ligand 13 with some trivalent lanthanide nitrates was elucidated by 1H NMR spectroscopic titrations and ESI-MS. Although 13 formed both 1:1 and 1:2 complexes with LaIII and YIII, only 1:2 complexes were observed with EuIII and CeIII. Quite unexpectedly, both alkyl-substituted ligands 12 and 13 showed lower solubilities in certain diluents than the unsubstituted ligand CyMe4-BTBP. Compared to CyMe4-BTBP, alkyl-substitution was found to decrease the rates of metal-ion extraction of the ligands in both 1-octanol and cyclohexanone. A highly efficient (DAm > 10) and selective (SFAm/Eu > 90) extraction was observed for 12 and 13 in cyclohexanone and for 13 in 1-octanol in the presence of a phase-transfer agent. The implications of these results for the design of improved extractants for radioactive waste treatment are discussed.

Adoption of certified organic production: evidence from Mexico

Adoption of organic production and subsequent entry into the organic market is examined using Mexican avocado producers as a case study. Probit analysis of a sample of 183 small-scale (<15ha) producers from Michoacán suggests that adoption is positively influenced by management and economic factors (e.g. production costs per hectare and making inputs), but also by social factors (e.g. membership of a producers’ association). Experience in agriculture has a significant but negative effect. Effective policy design must be therefore be aware of both the economic and social complexities surrounding adoption decisions.

Effects of soil conditions and drought on egg hatching and larval survival of the clover root weevil (Sitona lepidus)

Soil-dwelling insect herbivores are significant pests in many managed ecosystems. Because eggs and larvae are difficult to observe, mathematical models have been developed to predict life-cycle events occurring in the soil. To date, these models have incorporated very little empirical information about how soil and drought conditions interact to shape these processes. This study investigated how soil temperature (10, 15, 20 and 25 °C), water content (0.02 (air dried), 0.10 and 0.25 g g−1) and pH (5, 7 and 9) interactively affected egg hatching and early larval lifespan of the clover root weevil (Sitona lepidus Gyllenhal, Coleoptera: Curculionidae). Eggs developed over 3.5 times faster at 25 °C compared with 10 °C (hatching after 40.1 and 11.5 days, respectively). The effect of drought on S. lepidus eggs was investigated by exposing eggs to drought conditions before wetting the soil (2–12 days later) at four temperatures. No eggs hatched in dry soil, suggesting that S. lepidus eggs require water to remain viable. Eggs hatched significantly sooner in slightly acidic soil (pH 5) compared with soils with higher pH values. There was also a significant interaction between soil temperature, pH and soil water content. Egg viability was significantly reduced by exposure to drought. When exposed to 2–6 days of drought, egg viability was 80–100% at all temperatures but fell to 50% after 12 days exposure at 10 °C and did not hatch at all at 20 °C and above. Drought exposure also increased hatching time of viable eggs. The effects of soil conditions on unfed larvae were less influential, except for soil temperature which significantly reduced larval longevity by 57% when reared at 25 °C compared with 10 °C (4.1 and 9.7 days, respectively). The effects of soil conditions on S. lepidus eggs and larvae are discussed in the context of global climate change and how such empirically based information could be useful for refining existing mathematical models of these processes.

Variation in root-associated phosphatase activities in wheat contributes to the utilization of organic P substrates in vitro, but does not explain differences in the P-nutrition of plants when grown in soils

To understand whether genotypic variation in root-associated phosphatase activities in wheat impacts on its ability to acquire phosphorus (P), various phosphatase activities of roots were measured in relation to the utilization of organic P substrates in agar, and the P-nutrition of plants was investigated in a range of soils. Root-associated phosphatase activities of plants grown in hydroponics were measured against different organic P substrates. Representative genotypes were then grown in both agar culture and in soils with differing organic P contents and plant biomass and P uptake were determined. Differences in the activities of both root-associated and exuded phosphodiesterase and phosphomonoesterase were observed, and were related to the P content of plants supplied with either ribonucleic acid or glucose 6-phosphate, respectively, as the sole form of P. When the cereal lines were grown in different soils, however, there was little relationship between any root-associated phosphatase activity and plant P uptake. This indicates that despite differences in phosphatase activities of cereal roots, such variability appears to play no significant role in the P-nutrition of the plant grown in soil, and that any benefit derived from the hydrolysis of soil organic P is common to all genotypes.

Effect of cattle urine addition on the surface emissions and subsurface concentrations of greenhouse gases in a UK peat grassland

Grazing systems represent a substantial percentage of the global anthropogenic flux of nitrous oxide (N2O) as a result of nitrogen addition to the soil. The pool of available carbon that is added to the soil from livestock excreta also provides substrate for the production of carbon dioxide (CO2) and methane (CH4) by soil microorganisms. A study into the production and emission of CO2, CH4 and N2O from cattle urine amended pasture was carried out on the Somerset Levels and Moors, UK over a three-month period. Urine-amended plots (50 g N m−2) were compared to control plots to which only water (12 mg N m−2) was applied. CO2 emission peaked at 5200 mg CO2 m−2 d−1 directly after application. CH4 flux decreased to −2000 μg CH4 m−2 d−1 two days after application; however, net CH4 flux was positive from urine treated plots and negative from control plots. N2O emission peaked at 88 mg N2O m−2 d−1 12 days after application. Subsurface CH4 and N2O concentrations were higher in the urine treated plots than the controls. There was no effect of treatment on subsurface CO2 concentrations. Subsurface N2O peaked at 500 ppm 12 days after and 1200 ppm 56 days after application. Subsurface NO3− concentration peaked at approximately 300 mg N kg dry soil−1 12 days after application. Results indicate that denitrification is the key driver for N2O release in peatlands and that this production is strongly related to rainfall events and water-table movement. N2O production at depth continued long after emissions were detected at the surface. Further understanding of the interaction between subsurface gas concentrations, surface emissions and soil hydrological conditions is required to successfully predict greenhouse gas production and emission.

Effects of land management on different forms of soil carbon in olive groves in Mediterranean areas

This study analyses soil organic carbon (SOC) and hot-water extractable carbon (HWC), both measures of soil quality, under different land management: (1) conventional tillage (CT); (2) CT plus the addition of oil mill waste alperujo (A); (3) CT plus the addition of oil mill waste olive leaves (L); (4) no tillage with chipped pruned branches (NT1); and (5) no tillage with chipped pruned branches and weeds (NT2); in a typical Mediterranean agricultural area; the olive groves of Andalucía, southern Spain. SOC values in CT, A, NT1 and NT2 decreased with depth, but in NT2 the surface horizon (0-5 cm) had higher values than the other treatments, 47% more than the average values in the other three soils. In L, SOC also decreased with depth, although there was an increase of 88.5% from the first (0-10 cm) to the second horizon (10-16 cm). Total SOC stock values were very similar under A (101.9 Mg ha−1), CT (101.7 Mg ha−1), NT1 (105.8 Mg ha−1) and NT2 (111.3 Mg ha−1, if we consider the same depth of the others). However, SOC under L was significantly higher (p < 0.05) at 250.2 Mg ha−1. HWC decreased with depth in A, CT and NT1. NT2 and L followed the same pattern as the other management types but with a higher value in the surface horizon (2.3 and 4.9 mg g−1 respectively). Overall, our results indicate that application of oil mill waste olive leaves under CT (L) is a good management practice to improve SOC and reduce waste.

The effect of model configuration on modelled hillslope–riparian interactions

The transfer of hillslope water to and through the riparian zone forms a research area of importance in hydrological investigations. Numerical modelling schemes offer a way to visualise and quantify first-order controls on catchment runoff response and mixing. We use a two-dimensional Finite Element model to assess the link between model setup decisions (e.g. zero-flux boundary definitions, soil algorithm choice) and the consequential hydrological process behaviour. A detailed understanding of the consequences of model configuration is required in order to produce reliable estimates of state variables. We demonstrate that model configuration decisions can determine effectively the presence or absence of particular hillslope flow processes and, the magnitude and direction of flux at the hillslope–riparian interface. If these consequences are not fully explored for any given scheme and application, the resulting process inference may well be misleading.

Effect of prebiotics on the fecal microbiota of elderly volunteers after dietary supplementation of Bacillus coagulans GBI-30, 6086

In advancing age, gut populations of beneficial microbes, notably Bifidobacterium spp., show a marked decline. This contributes to an environment less capable of maintaining homoeostasis. This in vitro investigation studied the possible synergistic effects of probiotic supplementation in modulating the gut microbiota enabling prebiotic therapy to in elderly persons. Single stage batch culture anaerobic fermenters were used and inoculated with fecal microbiota obtained from volunteers after taking a 28 day treatment of Bacillus coagulans GBI-30, 6086 (GanedenBC30 (BC30)) or a placebo. The response to prebiotic supplements fructooligosaccharides (FOS) and galactooligosaccharides (GOS) in the fermenters was assessed. Bacterial enumeration was carried out using fluorescent in situ hybridisation and organic acids measured by gas chromatography. Baseline populations of Faecalibacterium prausnitzii, Clostridium lituseburense and Bacillus spp. were significantly higher in those having consumed BC30 compared to the placebo. Both prebiotics increased populations of several purportedly beneficial bacterial groups in both sets of volunteers. Samples from volunteers having ingested the BC30 also increased populations of C. lituseburense, Eubacterium rectale and F. prausnitzii more so than in persons who had consumed the placebo, this also resulted in significantly higher concentrations of butyrate, acetate and propionate. This shows that consumption of BC30 and subsequent use of prebiotics resulted in elevated populations of beneficial genres of bacteria as well as organic acid production

Modeling the photo-oxidation of dissolved organic matter by ultraviolet radiation in freshwater lakes: implications for mercury bioavailability

Uncertainties in projected ultraviolet (UV) radiation may lead to future increases in UV irradiation of freshwater lakes. Because dissolved organic carbon (DOC) is the main binding phase for mercury (Hg) in freshwater lakes, an increase in DOC photo-oxidation may affect Hg speciation and bioavailability. We quantified the effect of DOC concentration on the rate of abiotic DOC photo-oxidation for five lakes (DOC = 3.27–12.3 mg L−1) in Kejimkujik National Park, Canada. Samples were irradiated with UV-A or UV-B radiation over a 72-h period. UV-B radiation was found to be 2.36 times more efficient at photo-oxidizing DOC than UV-A, with energy-normalized rates of dissolved inorganic carbon (DIC) production ranging from 3.8 × 10−5 to 1.1 × 10−4 mg L−1 J−1 for UV-A, and from 6.0 × 10−5 to 3.1 × 10−4 mg L−1 J−1 for UV-B. Energy normalized rates of DIC production were positively correlated with DOC concentrations. Diffuse integrated attenuation coefficients were quantified in situ (UV-A Kd = 0.056–0.180 J cm−1; UV-B Kd = 0.015–0.165 J cm−1) and a quantitative depth-integrated model for yearly DIC photo-production in each lake was developed. The model predicts that, UV-A produces between 3.2 and 100 times more DIC (1521–2851 mg m−2 year−1) than UV-B radiation (29.17–746.7 mg m−2 year−1). Future increases in UV radiation may increase DIC production and increase Hg bioavailability in low DOC lakes to a greater extent than in high DOC lakes.

Effect of feeding intensity and milking system on nutritionally relevant milk components in dairy farming systems in the North East of England

There is increasing concern that the intensification of dairy production reduces the concentrations of nutritionally desirable compounds in milk. This study therefore compared important quality parameters (protein and fatty acid profiles; α-tocopherol and carotenoid concentrations) in milk from four dairy systems with contrasting production intensities (in terms of feeding regimens and milking systems). The concentrations of several nutritionally desirable compounds (β-lactoglobulin, omega-3 fatty acids, omega-3/omega-6 ratio, conjugated linoleic acid c9t11, and/or carotenoids) decreased with increasing feeding intensity (organic outdoor ≥ conventional outdoor ≥ conventional indoors). Milking system intensification (use of robotic milking parlors) had a more limited effect on milk composition, but increased mastitis incidence. Multivariate analyses indicated that differences in milk quality were mainly linked to contrasting feeding regimens and that milking system and breed choice also contributed to differences in milk composition between production systems.

Soil carbon and litter development along a reconstructed biodiverse forest chronosequence of South-Western Australia

Soil organic matter (SOM) increases with time as landscape is restored. Studying SOM development along restored forest chronosequences would be useful in clarifying some of the uncertainties in quantifying C turnover rates with respect to forest clearance and ensuing restoration. The development of soil organic matter in the mineral soils was studied at four depths in a 16-year-old restored jarrah forest chronosequence. The size-separated SOM fractionation along with δ13C isotopic shift was utilised to resolve the soil C temporal and spatial changes with developing vegetation. The restored forest chronosequence revealed several important insights into how soil C is developing with age. Litter accumulation outpaced the native forest levels in 12 years after restoration. The surface soils, in general, showed increase in total C with age, but this trend was not clearly observed at lower depths. C accumulation was observed with increasing restoration age in all three SOM size-fractions in the surface 0–2 cm depth. These biodiverse forests show a trend towards accumulating C in recalcitrant stable forms, but only in the surface 0–2 cm mineral soil. A significant reverse trend was observed for the moderately labile SOM fraction for lower depths with increasing restoration age. Correlating the soil δ13C with total C concentration revealed the re-establishment of the isotopically depleted labile to enriched refractory C continuum with soil depth for the older restored sites. This implied that from a pedogenic perspective, the restored soils are developing towards the original native soil carbon profile.

Considerations on the use of the p-nitrophenyl phosphomonoesterase assay in the study of the phosphorus nutrition of soil borne fungi

The p-nitrophenyl phosphomonoesterase assay (p NPPase) is commonly used to measure cell-wall-associated and extracellular phosphatase activity of soil fungi. p NPPases are usually assayed in the context of fungal nutrition, where inorganic P supply might be enhanced by the mineralisation of monoester organic P sources in the soil. The importance of the assay to the P nutrition of soil fungi is considered based on the evidence currently available including the consistency of methodological approach. The nature of organic P in the soil and the relevance of the assay to some specific soil substrates is discussed, particularly the chemistry and bioavailability of myo-inositol hexakisphosphate and the lower inositol phosphates. The evidence for the long-term stability of p NPPases in the soil is examined in the light of the persistence of p NPPase in soils. The role of persistent extracellular fungal p NPPases in the soil P cycle is discussed. Conclusions from p NPPase based studies must be based upon an appreciation of the constraints of the assay and the complex chemistry of organic P and p NPPase in the soil.

Some potential inaccuracies of the p -nitrophenyl phosphomonoesterase assay in the study of the phosphorus nutrition of soil borne fungi

The p-nitrophenol phosphomonoesterase assay (pNPPase) is commonly used to measure cell-wall-associated and extracellular phosphatase activity of soil fungi. pNPPases are usually assayed in the context of fungal nutrition, where inorganic P supply might be enhanced by the mineralisation of organic P sources in the soil. We report here on a series of experiments with the ectomycorrhizal basidiomycete Hebeloma cylindrosporum that highlight components of accepted methodology that might impinge on the reliability of the assay. These include the loss of pNPPase after filtration, inaccuracies in measuring wall-associated enzyme and the ample pool of intracellular pNPPase can be mistakenly measured as external pNPPase if cells are accidentally damaged.

Soil bacterial phoD gene abundance and expression in response to applied phosphorus and long-term management

Bacterial transformation of phosphorus (P) compounds in soil is largely dependent on soil microbial community function, and is therefore sensitive to anthropogenic disturbances such as fertilization or cropping systems. However, the effect of soil management on the transcription of bacterial genes that encode phosphatases, such as phoD, is largely unknown. This greenhouse study examined the effect of long-term management and P amendment on potential alkaline phosphatase (ALP) activity and phoD gene (DNA) and transcript (RNA) abundance. Soil samples (0–15 cm) were collected from the Glenlea Long-term Rotation near Winnipeg, Manitoba, to compare organic, conventional and prairie management systems. In the greenhouse, pots of soil from each management system were amended with P as either soluble mineral fertilizer or cattle manure and then planted with Italian ryegrass (Lolium multiforum). Soils from each pot were sampled for analysis immediately and after 30 and 106 days. Significant differences among the soil/P treatments were detected for inorganic P, but not the organic P in NaHCO3-extracts. At day 0, ALP activity was similar among the soil/P treatments, but was higher after 30 days for all P amendments in soil from organically managed plots. In contrast, ALP activity in soils under conventional and prairie management responded to increasing rates of manure only, with significant effects from medium and high manure application rates at 30 and 106 days. Differences in ALP activity at 30 days corresponded to the abundance of bacterial phoD genes, which were also significantly higher in soils under organic management. However, this correlation was not significant for transcript abundance. Next-generation sequencing allowed the identification of 199 unique phoD operational taxonomic units (OTUs) from the metagenome (soil DNA) and 35 unique OTUs from the metatranscriptome (soil RNA), indicating that a subset of phoD genes was being transcribed in all soils.

Effect of agitation on the performance of an anaerobic sequencing batch biofilm reactor in the treatment of dairy effluents

Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e. g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system`s agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition.