Flooding and the Role of Planning in England and Wales: A Critical Review

In this paper the authors raise some important questions about the extent to which planning is fostering an environment susceptible to flooding. They argue that severe UK flooding incidents in recent years should result in the government re-examining the planning system to ensure relevancy and effectiveness in dealing with such problems in the future. They identify where the current policy and practice weaknesses lie in planning to limit both flood source and flood impact areas and suggest ways in which the government and the profession could take remedial steps to increase local and regional sustainability.     

Aerosol composition as a function of haze and humidity levels in the Southwestern U.S.

The observed composition of visibility-reducing aerosols in the Grand Canyon region is summarized in climatological terms. Observations are from SCENES, a measurement program extending from 1984 to 1989. Results are presented as average mass balances stratified by various factors.Aerosols were found to exhibit substantial seasonal variation, but little systematic diurnal variation. Crustal material was a dynamic component, and peaked during springtime. Aerosol composition, but not total concentration, depended strongly on ambient relative humidity, with crustal material augmented at low humidities and sulfates augmented at high humidities. Total fine-particle concentrations correlated strongly with light scattering, as expected; however, little association between chemical composition and light scattering was observed.     

Visual prey detection by near-infrared cues in a fish

Many animal species are able to perceive light wavelengths beyond those visible to humans. While numerous species are additionally sensitive to short wavelengths (UV), long wavelengths such as the near-infrared spectrum (NIR) are supposed to be unsuitable for visual perception. Here, we experimentally show that under exclusive NIR illumination, the cichlid fish Pelvicachromis taeniatus displays a clear foraging response towards NIR reflecting prey. Additional control experiments without prey indicate that the observed behavior is not a mere response to the NIR environment. These results give first evidence for NIR visual sensitivity in a functional context and thus challenge the current view about NIR perception.     

Soil amendments, plant age, and intercropping impact p,p'-DDE bioavailability to Cucurbita pepo

Field experiments were conducted to optimize the phytoextraction of weathered p,p'-DDE (p,p'-dichlorodiphenyldichloroethylene) by Cucurbita subspecies. The effects of two soil amendments, mycorrhizae or a biosurfactant, on p,p'-DDE accumulation was determined. Also, p,p'-DDE uptake was assessed during plant growth (12, 26, 38, and 62 d), and cultivars that accumulate weathered p,p'-DDE were intercropped with cultivars known not to have that ability. Cucurbita pepo L. ssp. pepo accumulated large amounts of the contaminant, having stem bioconcentration factors, amounts of p,p'-DDE translocated, and contaminant phytoextraction that were 14, 9.9, and 5.0 times greater than C. pepo L. ssp. ovifera (L.) D.S. Decker, respectively. During 62 d, the stem BCF (bioconcentration factor) for p,p'-DDE in subspecies pepo remained constant and the total amount of contaminant accumulated was correlated with plant biomass (r(2) = 0.86). For subspecies ovifera, the stem BCF was highest at 12 d (1.5) but decreased to 0.39 by 62 d, and p,p'-DDE removal was not correlated with plant biomass. Mycorrhizal inoculation increased p,p'-DDE accumulation by both subspecies by an average 4.4 times. For subspecies pepo, mycorrhizae increased the percentage of contaminant extracted from 0.72 to 2.1%. Biosurfactant amendment also enhanced contaminant accumulation by both subspecies, although treatment reduced subspecies ovifera biomass by 60%. The biosurfactant had no effect on the biomass of subspecies pepo, increased the average contaminant concentration by 3.6-fold, and doubled the overall amount of p,p'-DDE removed from the soil. Soil amendments that enhance the mobility of weathered persistent organic pollutants will significantly increase the amount of contaminant phytoextraction by Cucurbita pepo.     

Using Ion-Exchange Resins to Study Soil Response to Experimental Watershed Acidification

Ion-exchange resins (IER) offer alternative approaches to measuring ionic movement in soils that may have advantages over traditional approaches in some settings, but more information is needed to understand how IER compare with traditional methods of measurement in forested ecosystems. At the Bear Brook Watershed in Maine (BBWM), one of two paired, forested watersheds is treated bi-monthly with S and N (28.8 and 25.2kgha⁻¹yr⁻¹ of S and N, respectively). Both IER and ceramic cup tension lysimeters were used to study soil solution responses after ∼11 years of treatment. Results from both methods showed treatments resulted in the mobilization of base cations and Al, and higher SO₄—S and inorganic N in the treated watershed. Both methods indicated similar differences in results associated with forest type (hardwoods versus softwoods), a result of differences in litter quality and atmospheric aerosol interception capacity. The correlation between lysimeter and IER data for individual analytes varied greatly. Significant correlations were evident for Na (r=0.75), Al (r=0.65), Mn (r=0.61), Fe (r=0.57), Ca (r=0.49), K (r=0.41) and NO₃—N (r=0.59). No correlation was evident between IER and soil solution data for NH₄—N and Pb. Both IER and soil solution techniques suggested similar interpretations of biogeochemical behavior in the watershed.     

Evidence for microfloral succession on allochthonous plant litter in Apalachicola Bay,Florida, USA

Changes in hydrolytic, respiratory,catabolic and lipid biosynthetic activities depend at least in part on successional changes in the microfloral populations of allochthonous plant litter incubated in a semi-tropical estuary. Initial colonization is by populations which have a high content of muramic acid relative to the adenosine triphosphate (ATP) and which are progressively displaced by a microflora with a lower ratio of muramic acid to ATP. Scanning electron micrography of the plant-litter microflora shows a succession of forms, with an initial bacterial colonization and its progressive displacement by more complex forms. Estimates of the microbial mass and the rates of phospholipid synthesis suggest that the detrital microflora has a relatively slow growth rate compared to its growth potential.     

Modelling PAHs adsorption and sequestration in freshwater and marine sediments

Chemical sequestration is a natural process taking place in sediments and soils which reduces the availability of hydrophobic compounds such as polycyclic aromatic hydrocarbons (PAHs). The rate of sequestration following the release of PAHs into the aquatic environment is still unexplored. To measure kinetic parameters and investigate governing factors of adsorption and sequestration of individual PAHs, natural sediment slurries were spiked with [2H]-PAHs and periodically extracted with a high molecular weight surfactant solution to determine changes in the available fraction over periods of 7-28 days. Dissolved and/or colloidal [2H]-PAHs were first adsorbed on particles within 4-7 days. Adsorbed molecules became slowly sequestered into sediment particles and were gradually more difficult to extract over a period of 17-20 days. An empirical model based on a three-compartment dynamic system was developed to quantify the sequestration rate constants of a group of seven selected PAHs. The sequestration process was assumed to be a first-order consecutive and irreversible two-stage reaction. The model was tested with lowly contaminated marine sediment and moderately contaminated freshwater sediment. Adsorption rate constants ranged between 0.056 h(-1) and 0.017 h(-1) and were approximately ten times higher than sequestration rate constants. Light PAHs were faster to enter into the sequestration process whereas colloidal dispersion of heavier less soluble PAHs reduced their adsorption rates. Although quite simple, this model was efficient to compute kinetic parameters for most PAHs studied and predict that only a small proportion of adsorbed PAHs would remain extractable after one month.     

Melamine-based organoclay to sequester atrazine

Sequestration of aqueous atrazine by organoclays prepared from the surfactant 6-piperazin-1-yl-N,N'-bis-(1,1,3,3-tetramethyl-butyl)-(1,3,5)triazine-2,4-diamine and Gonzales bentonite was assessed using 14C-labeled atrazine. Organoclays with varying ratios of surfactant to clay were evaluated with respect to their ability to sequester atrazine from an aqueous solution. Organoclays containing 100-200 g kg-1 surfactant on a total weight basis provided the most efficient adsorption of atrazine, with apparent KOC values exceeding 5000 l kg-1 at these loading fractions. Less than 12% of sequestered atrazine was released during four sequential day long washings, supporting our expectation that the majority of the reaction of atrazine with the surfactant lead to irreversible chemical bond formation through nucleophilic aromatic substitution.