In this paper, we present two years of seasonal nitric oxide (NO), ammonia (NH3), and nitrous oxide (N2O) trace gas fluxes measured in a recovering riparian zone with cattle excluded and adjacent riparian zone grazed by cattle. In the recovering riparian zone, average NO, NH3, and N2O fluxes were 5.8, 2.0, and 76.7 ng N m−2 s−1 (1.83, 0.63, and 24.19 kg N ha−1 y−1), respectively. Fluxes in the grazed riparian zone were larger, especially for NO and NH3, measuring 9.1, 4.3, and 77.6 ng N m−2 s−1 (2.87, 1.35, and 24.50 kg N ha−1 y−1) for NO, NH3, and N2O, respectively. On average, N2O accounted for greater than 85% of total trace gas flux in both the recovering and grazed riparian zones, though N2O fluxes were highly variable temporally. In the recovering riparian zone, variability in seasonal average fluxes was explained by variability in soil nitrogen (N) concentrations. Nitric oxide flux was positively correlated with soil ammonium (NH4+) concentration, while N2O flux was positively correlated with soil nitrate (NO3−) concentration. Ammonia flux was positively correlated with the ratio of NH4+ to NO3−. In the grazed riparian zone, average NH3 and N2O fluxes were not correlated with soil temperature, N concentrations, or moisture. This was likely due to high variability in soil microsite conditions related to cattle effects such as compaction and N input. Nitric oxide flux in the grazed riparian zone was positively correlated with soil temperature and NO3− concentration. Restoration appeared to significantly affect NO flux, which increased ≈600% during the first year following restoration and decreased during the second year to levels encountered at the onset of restoration. By comparing the ratio of total trace gas flux to soil N concentration, we show that the restored riparian zone is likely more efficient than the grazed riparian zone at diverting upper-soil N from the receiving stream to the atmosphere. This is likely due to the recovery of microbiological communities following changes in soil physical characteristics. 相似文献
The histology, histochemistry and ultrastructure of the cement gland cells of 3 species of sessile barnacles are described. Cells of both Elminius modestus
Darwin and Balanus balanoides (L.) (membranous bases) are similar histologically and ultrastructurally, and within the cells there are 2 distinct regions. One is the site of secretion accumulation, the other the site of secretion synthesis. In Balanus hameri
Ascanius (calcareous base) the cells are different in that the cytoplasm is more homogeneous. In all 3 species protein is the final secretion product (cement) of the cement cells. The mode of discharge of secretion from the cells differs between the membrane based and calcareous based barnacles. In the former, there is a series of collecting canals within the cytoplasm of the cement cells (intracellular canals) which join with the larger extracellular cement ducts. Secretion passes into the intracellular canals and is moved along to the larger cement ducts, which have an inner chitin lining. In Balanus hameri (calcareous base) there are no intracellular collecting canals. Secretions are thought to pass from the cement cells into the cement duct cells direct. The cement ducts in this species are not chitin lined. 相似文献
Data are presented on the biochemical analysis of protein, lipid, carbohydrate and ash for the ovary, testis, gut and body
wall of six species of elasipodid holothurians at a variety of stations in the Porcupine Seabight and Abyssal Plain (northeast
Atlantic Ocean). Samples were collected between 1980 and 1982. The species investigated were Benthogone rosea, Laetmogone violacea, Oneirophanta mutabilis, Deima validum, Benthodytes sordida and Psychropotes longicauda. Lipid was the dominant soluble constituent of the ovary and protein was dominant in the testis. Tissue calorific content
was determined from the biochemical data and by microbomb calorimetry. The ovaries had higher calorific values than the other
body tissues when determined by both methods. Comparison of the two methods suggests that the calorific values for testis,
gut and body wall are significantly different, and this may be a function of the calcium-carbonate content of these tissues.
Total-body calorific value varied from 24.26 J mg-1 ash-free dry weight (AFDW) (5 799 cal g-1 AFDW) to 25.43 J mg-1 AFDW (6 078 cal g-1 AFDW). Total holothurian-body calorific biomass at depths of 1 010, 2 000 and 4 000 m is 0.49, 3.69, and 0.25 kJ m-2 (118, 882, 59.4 cal m-2), respectively. Holothurians form a significant store of energy in the deep sea. 相似文献
Since 1994 data on fungal fruiting have been gathered in the Dawyck Botanic Garden outside Edinburgh, including that for eight plots within a 7.5 ha wood, which has been left unmanaged in order to investigate relationships amongst fungal succession, habitat characteristics and local weather patterns. The climatic data are provided by a small meteorological station situated on site. To handle nearly 4000 entries of data so far collected a computer database was constructed. This assists querying of the information so that changes in fungal communities and patterns of succession can be observed, and the relevant data extracted for further analysis. To aid in this analysis, and to give the user full control over editing, updating and querying the database, a special computer program was compiled.Analysis of the database records revealed that the currently known Dawyck fungal community comprises over 620 different taxa, and the species list increases every year. Although some species of mycorrhizal fungi showed high specificity towards their preferred host either at species (e.g. Lactarius blennius with beech, Lactarius quietus with oak, Russula fellea and Russula mairei with beech), or at genus level (e.g. Suillus spp. with Pinaceae), some other common fungi (e.g. of the genus Amanita) were found to have very wide host ranges. In addition, unusual mycorrhizal associations have also been recorded. A lime tree (Tilia), which is supposedly primarily endomycorrhizal, has been found regularly associated with Russula cyanoxantha, Russula parazurea, Russula pectinata and Inocybe fastigiata. Many common Scottish fungi were found to be associated with introduced exotic trees, which is illustrated on the example of Pseudotsuga menziesii (Douglas Fir).The software created utilises the Microsoft Office suite of programs. Microsoft Access was used to construct the database, and Microsoft Excel was used for statistical investigations. The software was programmed using Microsoft Visual Basic, and provided a means of extracting the necessary data stored in Access and controlling the formulae used in Excel for their analysis. The recorded seasonal patterns of fungal fruiting was successfully described by a simulation mathematical model comprising differential and algebraic equations. This model may now be used as a submodel within more complex models describing terrestrial ecosystem processes. Examples of model simulations and sensitivity analysis are given and implications for future research discussed. 相似文献
Two different conditioning procedures, one appetitive and the other aversive, were used in separate attempts to demonstrate response to magnetic fields in the goldfish, Carassius auratus. Our results lead us to question those of an orientation experiment by Becker, although we recognize the possibility that goldfish may be sensitive primarily to magnetic field direction rather than intensity and that their directional sensitivity may be evidenced most readily by orientation in the field. 相似文献
Objective: The objective of this study was to estimate the likely reduction in road trauma associated with the implementation of effective interventions to reduce road trauma among young Australians.
Methods: A desktop evaluation was conducted to model the likely reduction in road trauma (deaths and serious injuries resulting in hospitalization) among young people aged 17–24 years residing in Queensland, New South Wales, and Victoria. Potential interventions were identified using a rapid literature review and assigned a score based on evidence of effectiveness and implementation feasibility with the 3 highest scoring interventions included in the modeling. Likely reduction in road trauma was estimated by applying the average risk reduction effect sizes for each intervention to baseline risk (passenger or driver death or serious injury per 100,000 population) of road trauma for young Australians. Point estimates were calculated for the potential number of deaths and serious injuries averted in each state and per 100,000 population, with a one-way sensitivity analysis conducted using uncertainty ranges identified.
Results: Peer passenger and night driving restrictions as well as improved vehicle safety measures had the greatest potential to reduce road trauma. Peer passenger restrictions could avert 14 (range: 5–24) and 24 (range: 8–41) hospitalizations per year in Queensland and New South Wales, respectively, and night driving restrictions could avert 17 (range: 7–26), 28 (range: 12–45), and 13 (range: 6–21) hospitalizations annually in Queensland, New South Wales, and Victoria. These interventions reduced fatalities by less than 1 death annually in each state. Improved vehicle safety measures could avert 0–3, 0–4, and 0–3 deaths and 3–91, 4–156, and 2–75 hospitalizations in Queensland, New South Wales, and Victoria.
Conclusions: Key elements of graduated licensing (peer passenger and night driving restrictions) along with vehicle safety interventions offer modest but practically significant reductions in road trauma for young Australians. State governments need to revise current legislation to ensure that these reductions in road trauma can be realized. 相似文献
In Oslo, traffic has been one of the dominating sources of air pollution in the last decade. In one part of the city where most traffic collects, two tunnels were built. A series of before and after studies was carried out in connection with the tunnels in use. Dispersion models were used as a basis for estimating exposure to nitrogen dioxide and particulate matter in two fractions. Exposure estimates were based on the results of the dispersion model providing estimates of outdoor pollutant concentrations on an hourly basis. The estimates represent concentrations in receptor points and in a square kilometre grid. The estimates were used to assess development of air pollution load in the area, compliance with air quality guidelines, and to provide a basis for quantifying exposure-effect relationships in epidemiological studies. After both tunnels were taken in use, the pollution levels in the study area were lower than when the traffic was on the surface (a drop from 50 to 40 micrograms m-3). Compliance with air quality guidelines and other prescribed values has improved, even if high exposures still exist. The most important residential areas are now much less exposed, while areas around tunnel openings can be in periods exposed to high pollutant concentrations. The daily pattern of exposure shows smaller differences between peak and minimum concentrations than prior to the traffic changes. Exposures at home (in the investigation area) were reduced most, while exposures in other locations than at home showed only a small decrease. Highest hourly exposures are encountered in traffic. 相似文献
ABSTRACT: Studies were conducted to analyze the presence of 11 pesticide residues in 12 surface waters in the Piedmont and coastal plain regions of North Carolina. Samples were assayed using enzyme‐linked immunosorbent assays (ELISAs). All ELISA results of one part per billion (ppb, μg/L) or greater were confirmed using gas chromatography/mass spectrometry (GCIMS). ELISA detection limits were approximately an order of magnitude higher than GCJMS methods. Of the 5,035 analytical results from 742 surface water samples, atrazine was detected in approximately 45 percent of the samples, five of which were at or above the Maximum Contaminant Level (MCL) of 3‐ppb. Metolachlor was detected in 64 percent of the samples. Aldicarb, 2,4‐D, chlorpyrifos, and chlorothalonil were also detected, and each was found in less than 12 percent of the samples. The remaining pesticides, including carbaryl, acetochior, methomyl, carbofuran, and alachlor, were not detected during the study period. 相似文献
Herbarium specimens are increasingly recognized as an important resource for conservation science and virtual herbaria are making specimens freely available to a wider range of users than ever before. Few virtual herbaria are designed with conservation use as a primary driver. Exceptionally, Brazil's Reflora Virtual Herbarium (RVH) was created to increase knowledge and conservation of the Brazilian flora. The RVH is closely integrated with the Flora of Brazil 2020 platform on which Brazil's new national Flora is under construction. Both resources are accessible via the Reflora home page and thousands of users move seamlessly between these Reflora resources. To understand how the Reflora resources are currently used and their impact on conservation science, we conducted a literature review and an online survey. We searched for publications of studies in which Reflora resources were used and publications resulting from Brazilian researchers who were part of Reflora's research and mobility program. The survey contained multiple choice questions and questions that required a written response. We targeted Reflora webpage visitors with the survey to capture a wider range of Reflora users than the literature review. Reflora resources were used for a variety of conservation-relevant purposes. Half the 806 scientific publications in which Reflora was cited and 81% of the 1069 survey respondents accessing Reflora resources mentioned conservation-relevant research outputs. Most conservation-relevant uses of the Reflora resources in scientific publications were research rather than implementation focused. The survey of Reflora users showed conservation uses and impacts of virtual herbaria were more numerous and diverse than the uses captured in the literature review. Virtual herbaria are vital resources for conservation science, but they must document use and impacts more comprehensively to ensure sustainability. 相似文献