Wood ash use in forestry - a review of the environmental impacts

The use of wood fuel for energy production in the UK is setto increase in the near future as part of a government commitmentto increase renewable sources to 10 per cent by 2010. The ashgenerated as a by-product of combustion, whether for heat orpower generation, has potential use as a fertilizer in forestsystems. This review assesses the available information on factorsaffecting the quality of the ash and environmental implicationsarising from its application. The key determinants of wood ashchemistry are the tree species combusted, the nature of theburn process and the conditions at the application site. Woodash from hardwood species produces higher levels of macronutrientsin their ash than conifers, and the silica content is frequentlylower. A furnace temperature between 500 and 900°C is criticalto the retention of nutrients, particularly potassium, and determinesthe concentrations of potentially toxic metals including aluminiumin the ash. Fly ash, the lightest component that accumulatesin the flue system, can contain high concentrations of cadmium,copper, chromium, lead and arsenic and this ash should not beused as fertilizer. The form of the ash at application is important,with loose ash releasing Ca, K and Na more rapidly than granulatedash. Heavy metal, radionuclide and dioxin contamination of woodash-based fertilizers is minimal and unlikely to affect ecosystemfunction. The effects of wood ash are primarily governed byapplication rate and soil type. The benefits are maximized atlow dose rates, with possible toxicity from applications inexcess of 10 t ha^–1. For most forest sites, a single woodash application per rotation could replace all the nutrientslost after whole-tree harvesting (excepting N). Long-lastingpositive effects on tree growth have been observed on shallowpeats, in which the humus is slowly mineralized in responseto elevated pH and increased nutrient availability. In contrast,wood ash application to podzols is only effective in enhancingtree growth when nitrogen availability is non-limiting. To date,published research of wood ash effects on trees growing in claysand loams is minimal. A lag time for positive tree responsesto wood ash application is often observed, and may be the resultof phosphorous limitation at higher soil pH. The greatest reportedadverse ecological effects are to acidophilic ecosystems, particularlythe constituent bryophyte, soil bacteria and ectomycorrhizalcommunities.     

Effect of Oil Overlay on Inhibition Potential of Roscovitine in Sheep Cumulus‐Oocyte Complexes

Inhibitors of cyclin‐dependent kinases, as roscovitine, have been used to prevent the spontaneous resumption of meiosis in vitro and to improve the oocyte developmental competence. In this study, the interference of oil overlay on the reversible arrest capacity of roscovitine in sheep oocytes as well as its effects on cumulus expansion was evaluated. For this, cumulus‐oocyte complexes (COCs) were cultured for 20 h in TCM 199 with 10% foetal bovine serum (Control) containing 75 μm roscovitine (Rosco). Subsequently, they were in vitro matured (IVM) for further 18 h in inhibitor‐free medium with LH and FSH. The culture was performed in Petri dishes under mineral oil (+) or in 96 well plates without oil overlay (?) at 38.5°C and 5% CO₂. At 20 and 38 h, the cumulus expansion and nuclear maturation were evaluated under stereomicroscope and by Hoechst 33342 staining, respectively. No group presented cumulus expansion at 20 h. After additional culture with gonadotrophins, a significant rate of COCs from both Control groups (+/?) exhibited total expansion while in both Rosco groups (+/?) the partial expansion prevailed. Among the oocytes treated with roscovitine, 65.2% were kept at GV in the absence of oil overlay while 40.6% of them reached MII under oil cover (p < 0.05). This meiotic arrest was reversible, and proper meiosis progression also occurred in the Control groups (+/?). So, the culture system without oil overlay improved the meiotic inhibition promoted by roscovitine without affecting the cumulus expansion rate or the subsequent meiosis progression.     

Electrical responses of insect central neurons: augmentation by nerve section or colchicine

Intracellular recording from the somata of central motor neurons in the cockroach Periplaneta americana normally shows little or no electrical response evoked by soma depolarization or by antidromic stimulation. Within 4 days after either cutting the axon or administration of colchicine, large action potentials can regularly be recorded from cell bodies of metathoracic motor neurons. Each experimental procedure evokes formation of a dense, perinuclear ribonucleic acid ring in the soma of neurons showing augmented electrical responses.     

Follow-up of mercury levels in fish,human hair and urine in the Madeira and Tapajós basins,Amazon, Brazil

Informal economy of gold mining has contaminated some important river basins in Amazon. Follow-up studies on critical compartments showed some areas with high Hg levels in fish as well as in human hair samples. Average Hg in piscivorous fish in the Madeira river itself was 846 ppb (N=284) with a maximum of 3921 ppb. Mercury in fish from non polluted areas in this basin shows high variability, even for single species. A seasonal variation in Hg content was observed, with higher values at the end of the dry season. In the upper Tapajós basin comparable values were found for fish but with a definite decreasing trend downstream. Average value for piscivorous fish in the whole Tapajós basin is 482 ppb (N=122) with a maximum value of 3770 ppb. Hair Hg was higher in fishing villages in the Tapajós (average: 17 ppm; with N=432 and maximum value of 176 ppm) than in the Madeira (average: 9 ppm; N=169; maximum 71 ppm), and data from some areas of the Tapajós suggest a decrease with time. Mercury was much higher in urine of goldshop workers in Santarém (low Tapajós) than in Alta Floresta (high Tapajbs) and show a decreasing trend in both cases, probably related to the significant decline in gold mining activities during the study period (1986–1994).     

Acute and chronic disability among U.S. farmers and pesticide applicators: the National Health Interview Survey (NHIS)

The National Health Interview Survey (NHIS) is a multipurpose household survey of the U.S. civilian non-institutionalized population conducted annually since 1957. From 1986 to 1994, over 450,000 U.S. workers, age 18 years and older, participated in a probability sampling of the entire non-institutionalized U.S. population; variables collected included a range of measures of acute and chronic disability. The objective of the present study was to assess predictors of health status, and acute and chronic disability for farmers and pesticide applicators (pesticide-exposed workers) compared to all other U.S. workers using the 1986-1994 NHIS. After adjustment for sample weights and design effects using SUDAAN, several measures of acute and chronic disability and health status were modeled with multiple logistic regression. Farmers (n = 9576) were significantly older compared to all other U.S. workers (n = 453,219) and pesticide applicators (n = 180). Farmers and pesticide applicators had a higher proportion of males, whites, and Hispanics and were less educated. After adjusting for age, gender, race-ethnicity, and education, compared to all other workers, farmers were significantly less likely to report acute and chronic disability and health conditions, while pesticide applicators were more likely to report chronic disability, health conditions, and poor health. Given the cross-sectional nature of the data and the significant job demands of farming, both leading to a relative healthy worker effect, the present results indicate that at any point in time, farmers report less acute and chronic disability, compared to other U.S. workers, whereas pesticide applicators report similar or poorer health.     

Major compositional units of the moon: lunar prospector thermal and fast neutrons

Global maps of thermal and fast neutron fluxes from the moon suggest three end-member compositional units. A high thermal and low fast neutron flux unit correlates with the lunar highlands and is consistent with feldspathic rocks. The South Pole-Aitken basin and a strip that surrounds the nearside maria have intermediate thermal and fast neutron flux levels, consistent with more mafic rocks. There appears to be a smooth transition between the most mafic and feldspathic compositions, which correspond to low and high surface altitudes, respectively. The maria show low thermal and high fast neutron fluxes, consistent with basaltic rocks.     

Lunar Fe and Ti abundances: comparison of lunar prospector and clementine data

The Lunar Prospector neutron spectrometer data correlate well with iron and titanium abundances obtained through analysis of Clementine spectral reflectance data. With the iron and titanium dependence removed, the neutron spectrometer data also reveal regions with enhanced amounts of gadolinium and samarium, incompatible rare earth elements that are enriched in the final phases of magma crystallization. These regions are found mainly around the ramparts of the Imbrium impact basin but not around the other basins, including the much larger and deeper South Pole-Aitken basin. This result confirms the compositional uniqueness of the surface and interior of the Imbrium region.     

Organogenesis and foetal haemodynamics during the normal gestation of healthy black‐rumped agoutis (Dasyprocta prymnolopha,Wagler, 1831) bred in captivity

The objective of this study was to define the patterns of organogenesis and foetal haemodynamics during the normal gestation of healthy agoutis (Dasyprocta prymnolopha) kept in captivity. Thirty pregnant agoutis that ranged in size from small to medium and weighed between 2.5 and 3 kg underwent B‐mode and Doppler ultrasonography for the biometric evaluation of the foetal organs. The foetal aortic blood flow proved to be predominantly systolic, and the measured flow velocity was 78.89 ± 2.95 cm/s, with a maximum pressure gradient of 2.12 ± 0.27 mmHg. The liver was characterized by its large volume, occupying the entire cranial aspect of the abdominal cavity, and it was associated cranially with the diaphragm and caudally with the stomach. The flow velocity in the portal vein was estimated to equal 12.17 ± 2.37 cm/s, with a resistivity index of 0.82 ± 0.05. The gallbladder was centrally located and protruded cranially towards the diaphragm. The spleen was visualized as an elongated structure with tapered cranial and caudal extremities, and the foetal kidneys were visualized bilaterally in the retroperitoneal region, with the right kidney positioned slightly more cranially than the left. The morphological characterization and hemodynamic analysis of the foetal organs of black‐rumped agoutis via B‐mode and Doppler ultrasonography allow determination of the vascular network and of reference values for the blood flow required for perfusing the anatomical elements essential for maintaining the viability of foetuses at different gestational ages.     

SYBR Green real-time quantitative PCR for the specific detection and quantification of ‘Candidatus Liberibacter solanacearum’ in field samples from New Zealand

Diseases of solanaceous crops caused by the phloem-limited bacterium ‘Candidatus Liberibacter solanacearum’ (Lso), vectored by the tomato potato psyllid Bactericera cockerelli, pose a major economic threat to crop production. Lso is yet to be cultured and, therefore, effective control strategies depend heavily on the early detection of the pathogen via polymerase chain reaction (PCR) assays. In this study, two new assays for the detection of Lso in New Zealand field samples were developed, and compared with previously available assays. Firstly, a single-tube semi-nested gel-based PCR assay was developed for the genus-specific detection of liberibacter species, and shown to provide increased sensitivity over standard and nested PCR. Secondly, a single-tube semi-nested SYBR Green real-time PCR (qPCR) assay was developed for the specific detection of Lso in field samples from New Zealand, with a limit of detection of five copies of the target gene per reaction. Semi-nested qPCR showed similar sensitivity compared with TaqMan qPCR with the primer-probe combination LsoF-HLBpr and was 10- to 50-fold more sensitive than the conventional PCR assays tested. Quantification of titre in Lso-affected tubers by SYBR Green qPCR revealed a positive relationship between pathogen titre and the discolouration of fried tuber slices, a symptom indicative of Lso infection. Quantification of Lso in field samples of potato and tomato also revealed many samples with titres below the limit of detection of conventional PCR. The observation of low-titre samples demonstrated the utility of SYBR Green qPCR for detection of Lso, as in addition to increased sensitivity melt-curve analysis enables confirmation of qPCR data by identifying false positive results.