A lysimeter experiment to investigate temporal changes in the availability of pesticide residues for leaching

Leaching of three pesticides (isoproturon, chlorotoluron and triasulfuron) and a tracer (bromide) were determined in four contrasting soils ranging in texture from sandy loam to clay. The compounds were applied to undisturbed columns of soil and four columns for each soil were randomly selected and leached with 24-mm equivalent of water at prescribed time intervals (3, 9, 24, 37 and 57 d after application). A rapid decline in leached loads of isoproturon and chlorotoluron as time from application to irrigation increased was observed in all soils. In contrast, triasulfuron and bromide loads only decreased rapidly in the clay soil. Bromide losses decreased with decreasing clay contents of the soil and therefore with a decrease in structural development. Magnitudes of pesticide losses varied from soil to soil, depending on structural development and the organic carbon content. Pesticide degradation experiments on disturbed and undisturbed soil samples showed that the rapid decline of leached loads with time was faster than could be explained by degradation alone. Five physico-chemical processes are put forward to explain the different patterns of pesticide leached loads observed in the soils: (1) relative extent of preferential flow, (2) sorption capacity of the compounds to the different soils, (3) extent of degradation of the compounds in the soil, (4) variation in sorption kinetics between compounds associated with pesticide diffusion into soil aggregates, and (5) protection of the compounds by a combination of intra-aggregate diffusion and the presence of preferential flow pathways.     

Nitrogen trace gas emissions from a riparian ecosystem in southern Appalachia

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.     

The histology,histochemistry and ultrastructure of the cement apparatus of three adult sessile barnacles,Elminius modestus,Balanus balanoides and Balanus hameri

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.     

Organic and calorific content of the body tissues of deep-sea elasipodid holothurians in the northeast Atlantic Ocean

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.     

Analysis of fungal fruiting patterns at the Dawyck Botanic Garden

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.     

Attempts to train goldfish to respond to magnetic field stimuli

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.     

Road trauma among young Australians: Implementing policy to reduce road deaths and serious injury

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.     

Air pollution exposure monitoring and estimation. Part V. Traffic exposure in adults

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.     

“It's easy to throw rocks at a corporation”: wind energy development and distributive justice in Canada

In places like Canada, fast-paced wind turbine development combined with policy that limits local decision-making power has resulted in strong opposition to specific projects. Some studies suggest that anti-wind sentiment is tied to inadequate financial benefits – especially sharing at the local level. Thus, ideas of distributive economic justice have received traction, particularly in the form of praise for community-based development models. This paper reports on the findings from a mixed-methods study concerning preferred distributive justice elements in rural communities in Ontario (technocratic-based model) and Nova Scotia (community-based model) living with turbines. Residents’ perceptions of economic benefits are nuanced, but unlike other studies, this empirical work shows that both the fair distribution and the amount of local benefits are important predictors of project support. Yet, concerns around the fair distribution of benefits dominate in a regression on the adequacy of those benefits. A variety of interview and survey findings further point to the strength of traditional, profit-sharing community-based models for distributing benefits, but also more novel ideas including lowered electricity bills and tax rebates in areas home to turbines.     

What fraction of the organic carbon in sacoglossans is obtained from photosynthesis by kleptoplastids? An investigation using the natural abundance of stable carbon isotopes

any sacoglossans (opisthobranch gastropods) have the potential for carbon acquisition from photosynthesis by plastids sequestered from their macroalgal food as well as by ingestion, digestion and assimilation of the organic carbon derived from the alga. A new method for obtaining a minimum estimate of the fraction of sacoglossan carbon supplied from photosynthesis by kleptoplastids is suggested, based on the mass balance of stable carbon isotopes at the natural abundance level. The method involves comparison of ¹³C/¹²C ratios in sacoglossans with those of the algae on which they are found. Differences in ratios between alga and sacoglossan are used to give a minimum estimate of carbon acquisition by kleptoplasty, granted assumptions about the range of ¹³C/¹²C fractionation values which can occur for marine photolithotrophs. The new method is applied to several green (ulvophycean) alga–sacoglossan associations from Rottnest Island, Western Australia, and the values compared with those obtained previously by other means. The method suggests values of up to 0.6 of the total carbon input to the sacoglossans from photosynthesis by their kleptoplastids. To improve the estimates of the minimum role of kleptoplastidy in the carbon nutrition of sacoglossans, further information is needed: (1) on the fidelity of a given sacoglossan to a given algal individual (or species), (2) on the ¹³C/¹²C ratio of the part of the alga ingested by the sacoglossan, and (3) on the allocation of dietary organic carbon and of kleptoplastidic photosynthate to carbon lost in respiration, mucopolysaccharide production and gametes (and hence not sampled with the animal). Received: 24 November 1999 / Accepted: 20 October 2000