EVALUATION OF EROSION CONTROL PRODUCTS WITH AND WITHOUT ADDED POLYACRYLAMIDE1

ABSTRACT: Polyacrylamide (PAM) has been demonstrated to greatly reduce erosion in furrow irrigation, but much less is known about its effectiveness on the much steeper slopes typical of construction sites. The purpose of this study was to determine if anionic PAM would enhance erosion control either alone on bare soil or in combination with four types of ground covers commonly used for grass establishment: straw, straw erosion control blanket (ECB), wood fiber, and mechanically bonded fiber matrix (MBFM). Tests were conducted under natural rainfall and vegetation on a 4 percent slope (bare soil, straw, ECB, and MBFM) or using a rainfall simulator (bare soil, straw, wood fiber, MBFM) on either 10 percent or 20 percent slope on three different soil substrates. All ground cover treatments were evaluated with and without PAM applied in solution at 19 kg/ha. The straw, ECB, and MBFM significantly reduced runoff volume, average turbidity, and total sediment lost over five rainfall events on the vegetated plots. The addition of PAM to ground covers only occasionally had significant effects on runoff parameters but did significantly increase vegetative coverage overall. The rainfall simulator tests produced similar results after four events, with the straw, wood fiber, and MBFM all having significantly lower turbidity than the bare soil. The PAM significantly reduced turbidity for both the first and second events but did not consistently improve runoff quality after multiple rainfall events for any ground cover‐soil combinations tested. Separate tests of PAM applied before or after straw did not indicate a clear advantage of either approach, but runoff turbidity was often significantly reduced with PAM, especially at the 20 percent slope. Turbidity reductions were attributed to flocculation of eroded sediment.     

Calcium protects roots of Sedum alfredii H. against cadmium-induced oxidative stress

Sedum alfredii is a well-known Cd (cadmium) hyperaccumulator native to China. The impacts of exogenous Ca on Cd-induced oxidative stress and antioxidant systems in roots of S. alfredii were investigated by using cellular and biochemical approaches. Supplementation of the medium with higher Ca levels resulted in alleviated growth inhibition and decreased Cd concentration, as well as increased Ca concentration in roots. Cadmium induced lipid peroxidation and loss of plasma membrane integrity, reactive oxygen species overproduction, as well as ultrastructural changes of root cells were largely reversed by Ca supplementation in the medium. Calcium application significantly altered the Cd effects on antioxidant enzymes and non-enzyme antioxidants (non-protein thiols), and significantly increased glutathione (GSH) biosynthesis. The results suggest that Ca is able to protect the roots of S. alfredii against Cd toxicity by restoration of Cd-displaced Ca, alleviation of the metal induced oxidative stress, as well as promotion of GSH biosynthesis.     

Scenario analysis for regional decision-making on sustainable multifunctional land uses

Land-use patterns are influenced by both top-down and bottom-up (local) factors, with their interactions varying in both space and time. This provides a major challenge to decision-making for sustainable multifunctional landscapes. A cross-scale scenario structure has been developed to integrate top-down and bottom-up context based upon the familiar IPCC Special Report on Emission Scenarios framework. Qualitative scenario storylines are converted into multiple quantified simulations of regional land-use change using a series of rules, with information translated across scales using a hierarchical land-use classification. Land-use parcels (fields) are used as key landscape reference units representing the local dimension of regional changes. Biophysical limitations on land use are represented through land capability classes (climate, soils and topography). Socio-economic factors are characterised in reference to global drivers, policy targets or local preferences. A flexible stochastic software tool (LandSFACTS) ensures spatiotemporal coherence of land-use allocation simulations consistent with scenario storylines. Scenario development is designed to be interactive, bridging ‘problem-focussed’ and ‘actor-focussed’ approaches. A case study is presented from NE Scotland, where plans to enhance multifunctionality through new woodland are evaluated against drivers of globalisation and climate change. Competing priorities, such as food security, mean that in some scenarios, a policy objective for woodland expansion to occur on farmland cannot be met. Woodland expansion would then have to occur on uncultivated upland areas. Scenario analysis has highlighted specific sensitivity to change in ‘marginal’ agricultural areas, with the varying influence of different top-down or bottom-up factors leading to divergent potential outcomes.     

The effects of temperature and pressure acclimation on the temperature and pressure tolerance of the shallow-water shrimp Palaemonetes varians

Anthropogenic effects on marine ecosystems (e.g. hypoxia, warming) at and beyond continental margins are assumed to affect physiological and biochemical boundaries to species’ distributions, potentially leading to habitat contraction across depth. Whether or not shallow-water benthic invertebrates are capable of undergoing depth-related migrations in response to such perturbations remains largely unknown. The few studies available have focused solely on whether colonisation of deep waters may be ongoing and on the ability of shallow-water species to tolerate low temperatures and high hydrostatic pressures: two physical parameters, which are thought to limit the depth range of a species. Those studies did not consider the effects of acclimation to low temperature and, especially, acclimation to high hydrostatic pressure on pressure tolerance. We demonstrate that acclimation to both low temperature (5 °C) and to high hydrostatic pressure (10 MPa) increases the pressure tolerance within the shallow-water shrimp Palaemonetes varians. Previous studies have demonstrated the impressive temperature and pressure tolerance of this shallow-water shrimp. Here, we provide evidence that a shallow-water species may acclimate to low temperature and high pressure and show greater pressure tolerance, suggesting that shallow-water organisms may be able to rapidly—and potentially stepwise—acclimate to the low temperature and high pressure conditions typical of the deep sea. These findings are of importance for understanding phylogenetic development from shallow- to deep-water species and the processes behind past, present and future bathymetric range shifts in species.     

Genetic variation among trait groups and apparent absence of close inbreeding in grey-crowned babblers

Summary The grey-crowned babbler, Pomastostomus temporalis, is a non-migratory species with delayed breeding and prolonged association of young with siblings and parents. Since these conditions are conducive to incestuous matings, we have studied allozymic variation in a population in southeastern Queensland, to evaluate the possibility of close inbreeding. Eight of 20 loci tested were polymorphic, with an average proportion of heterozygous loci individual of 9.4%. No deficiency of heterozygotes was found, indicating the absence of detectable inbreeding. Some mechanism that prevents inbreeding seems to be present.     

Territoriality,defensible space and residential burglary: An environmental analysis

Previous research on territoriality suggests that territorial intrusion is associated with particular territorial demarcations. In the present study the use of territorial displays involving symbolic barriers, actual barriers, detectability, traces and social climate is related to the territorial intrusion of residential burglary. The five classes of territorial displays were assessed for a total of 306 burglarized houses on burglarized blocks, non-burglarized houses on burglarized blocks, and non-burglarized houses on non-burglarized blocks. After the data were reduced through factor analysis, multiple regression analysis revealed that burglarized houses differed from non-burglarized houses on non-burglarized blocks on four of the five classes of territorial displays. In general, burglarized houses had salient public territorial qualities: cues of openness and unoccupied appearance. In contrast, the non-burglarized houses had salient secondary or primary territorial qualities: territorial markers communicating privacy and individuality. In addition, non-burglarized houses had greater visual contact with neighboring houses.     

Duchenne muscular dystrophy associated with fetal pleural effusion and polyhydramnios

A case of fetal pleural effusion in a fetus affected with Duchenne muscular dystrophy (DMD) is reported. This case is discussed in the context of the previous observation of frequent stillbirths among male fetuses in DMD families.