PAHs associated with the leaves of three deciduous tree species. II: uptake during a growing season.

Leaves from three species of deciduous tree (oak, ash and hazel) were sampled at intervals through a growing season in a mature, mixed-deciduous woodland. Polycyclic aromatic hydrocarbon (PAH) concentrations remained within a small range for all species between May and September, deviating significantly only when increases in atmospheric concentrations of PAHs (notably from the 'Bonfire night' festival in early autumn) have been shown. We concluded that the influence of air concentrations was more important than meteorological conditions (temperature, humidity and rainfall) in determining plant concentrations of PAHs over a growing season. Concentrations of 4-, 5- and 6-ring PAHs were positively correlated with time for all species, but there were significant differences in the PAH profile between species sampled from the canopy (oak and ash) compared with the understorey (hazel). Oak and ash had similar PAH profiles, while hazel leaves had proportionally greater concentrations of the heavier molecular weight (4-, 5- and 6-ring) PAHs, and the ratios of these compounds to 3-ring PAHs was positively correlated with time. This affirms earlier work conducted on the same species in the same woodland, where we concluded that the canopy was filtering particles and attendant PAHs from air passing over or through it, and that these particles were transferred to the understorey and the woodland floor.     

Contaminated land clean-up using composted wastes and impacts of VOCs on land

This paper describes experiments that demonstrate the effects and potential for remediation of a former steelworks site in Wales polluted with polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs). Under field conditions, PAH-contaminated soil was composted in-vessel, with or without organic feedstocks, receiving forced aeration for 80 days followed by 4 months maturation. Treatments compared PAH removal in contaminated soil to contaminated soil mixed with three different organic waste mixes after composting and after composts were spread to land. After composting, PAH concentrations declined in all treatments, by up to 38%. Sixteen months after the composts were landspread and vegetation was established, only those containing contaminated soil with organic additions exhibited further PAH removal, by up to 29%. Composting resulted in a decline in the relative concentration of small PAHs, whereas the landspreading-vegetation phase saw a decline in the relative concentration of medium PAHs in two of the three composts exhibiting PAH removal. Under controlled glasshouse conditions, vegetated soil columns of differing depths were exposed to VOCs from beneath. VOC vapour affected both shoot and root growth and soil microbial activity; effects varied with distance from the VOC source. This work demonstrated that on-site remediation of aged PAH-contaminated land can be successfully initiated by in-vessel co-composting followed by land spreading and vegetation, within a practical timeframe.     

Lime/Limestone Scrubber Operation and Control

This paper examines operating and control experience obtained at full-scale lime-limestone scrubber systems both in the eastern and western United States. Methods of resolving typical problems in pH control of reagent feed, water balance closure, and slurry solids de-watering are discussed and described. Control problems can be severely aggravated by scale formation inside scrubbing equipment, especially on control sensors. If the sensor reliability problems can be resolved in a properly-designed scrubbing system, then the scrubber chemistry can generally be controlled and scale formation can usually be prevented. Current regulatory trends towards zero blowdown requirements increase scrubber operating and control problems, both from a process control standpoint (due to system complexity) and from a sensor reliability standpoint (due to an increased likelihood for chemical scale formation). These factors highlight the need for continuing development of improved scrubbing systems.     

Quantifying structural physical habitat attributes using LIDAR and hyperspectral imagery

Structural physical habitat attributes include indices of stream size, channel gradient, substrate size, habitat complexity, and riparian vegetation cover and structure. The Environmental Monitoring and Assessment Program (EMAP) is designed to assess the status and trends of ecological resources at different scales. High-resolution remote sensing provides unique capabilities in detecting a variety of features and indicators of environmental health and condition. LIDAR is an airborne scanning laser system that provides data on topography, channel dimensions (width, depth), slope, channel complexity (residual pools, volume, morphometric complexity, hydraulic roughness), riparian vegetation (height and density), dimensions of riparian zone, anthropogenic alterations and disturbances, and channel and riparian interaction. Hyperspectral aerial imagery offers the advantage of high spectral and spatial resolution allowing for the detection and identification of riparian vegetation and natural and anthropogenic features at a resolution not possible with satellite imagery. When combined, or fused, these technologies comprise a powerful geospatial data set for assessing and monitoring lentic and lotic environmental characteristics and condition.     

Simple models of massive epidemics of herpesvirus in Australian (and New Zealand) pilchards.

In March 1995, a mass mortality of pilchard started to occur in South Australia. This spread very rapidly throughout the Australian pilchard's range, later reaching New Zealand. In November 1998, a similar mass mortality broke out in South Australia and also spread, at a slower rate, throughout the Australian range. The mortality appeared to be caused by a herpesvirus. The mortality spread as a classical epidemic front, but its speed of progress and the brief duration of mortalities at a given location are extreme. We apply simple epidemic modelling techniques, SIR and SEIR modelling, to examine the factors behind the spread of this mortality and the differences between the 1995 and 1998/9 epidemics. We discuss biological factors influencing the critical processes of long-distance (D) and local (beta) transmission of infection.     

Data fusion modeling for groundwater systems

Engineering projects involving hydrogeology are faced with uncertainties because the earth is heterogeneous, and typical data sets are fragmented and disparate. In theory, predictions provided by computer simulations using calibrated models constrained by geological boundaries provide answers to support management decisions, and geostatistical methods quantify safety margins. In practice, current methods are limited by the data types and models that can be included, computational demands, or simplifying assumptions. Data Fusion Modeling (DFM) removes many of the limitations and is capable of providing data integration and model calibration with quantified uncertainty for a variety of hydrological, geological, and geophysical data types and models. The benefits of DFM for waste management, water supply, and geotechnical applications are savings in time and cost through the ability to produce visual models that fill in missing data and predictive numerical models to aid management optimization. DFM has the ability to update field-scale models in real time using PC or workstation systems and is ideally suited for parallel processing implementation. DFM is a spatial state estimation and system identification methodology that uses three sources of information: measured data, physical laws, and statistical models for uncertainty in spatial heterogeneities. What is new in DFM is the solution of the causality problem in the data assimilation Kalman filter methods to achieve computational practicality. The Kalman filter is generalized by introducing information filter methods due to Bierman coupled with a Markov random field representation for spatial variation. A Bayesian penalty function is implemented with Gauss–Newton methods. This leads to a computational problem similar to numerical simulation of the partial differential equations (PDEs) of groundwater. In fact, extensions of PDE solver ideas to break down computations over space form the computational heart of DFM. State estimates and uncertainties can be computed for heterogeneous hydraulic conductivity fields in multiple geological layers from the usually sparse hydraulic conductivity data and the often more plentiful head data. Further, a system identification theory has been derived based on statistical likelihood principles. A maximum likelihood theory is provided to estimate statistical parameters such as Markov model parameters that determine the geostatistical variogram. Field-scale application of DFM at the DOE Savannah River Site is presented and compared with manual calibration. DFM calibration runs converge in less than 1 h on a Pentium Pro PC for a 3D model with more than 15,000 nodes. Run time is approximately linear with the number of nodes. Furthermore, conditional simulation is used to quantify the statistical variability in model predictions such as contaminant breakthrough curves.     

The genetic mating system of a sex-role-reversed pipefish (Syngnathus typhle): a molecular inquiry

In the pipefish Syngnathus typhle as in other species of Syngnathidae, developing embryos are reared on the male's ventral surface. Although much laboratory research has been directed toward understanding sexual selection in this sex-role-reversed species, few studies have addressed the mating behavior of S. typhle in the wild, and none has capitalized upon the power of molecular genetic assays. Here we present the first direct assessment of the genetic mating system of S. typhle in nature. Novel microsatellite loci were cloned and characterized from this species, and employed to assay entire broods from 30 pregnant, field-captured males. Genetic analysis of 1340 embryos revealed that 1–6 females (mean = 3.1) contributed to each brooded clutch, the highest rate of multiple maternity yet documented in any pipefish. Evidence of multiple mating by females was also detected. Thus, this population of S. typhle displays a polygynandrous mating system, a finding consistent with previous field and laboratory observations. Our results, considered together with similar studies of other syngnathid species, provide preliminary support for the hypothesis that the genetic mating system is related to the evolution of sexual dimorphism in the fish family Syngnathidae. Received: 19 January 1999 / Received in revised form: 15 April 1999 / Accepted: 9 May 1999     

Activity of insect juvenile hormone III: seed germination and seedling growth studies

Summary. Juvenile hormones are sesquiterpenoids that regulate developmental processses such as metamorphosis and reproduction in insects. Insect juvenile hormone III (JH III), methyl-10R,11-epoxy-3,7,11-trimethyl-2E,6E-dodecadienoate, has also been identified in two sedge species, Cyperus iria and C. aromaticus (Toong et al. 1988). Potential allelopathic activity of this compound and the structurally related sesquiterpenoid farnesol was investigated using seed germination and seedling growth assays with radish, lettuce and rice. Treatment of seeds with JH III delayed lettuce seed germination and potently inhibited rice shoot growth. Both farnesol and JH III inhibited the growth of C. iria seedlings. The antimicrobial activity of JH III was also tested on a taxonomic and ecologically diverse range of fungi. Using the classic cytotoxic disk assay, JH III did not effect growth of the fungal species tested. We believe that JH III may contribute to the aggressive nature of this invasive weed species. Received 11 October 1999; accepted 26 February 2000