http://hdl.handle.net/10453/174 2013-05-23T11:50:07Z http://hdl.handle.net/10453/19076 Heavy metal distribution in estuarine sediments: a comparison of a seagrass bed and adjacent bare sediment Dowsett Noni; Rayburg Scott Eric M. Valentine Seagrasses are highly productive and dynamic ecosystems, which supply a range of ecosystem services. Despite this, seagrass communities are globally in decline, largely due to anthropogenic influences. Urban and agricultural development, coupled with poor land management practices, can result in increased pollutants entering estuaries. Sediments below seagrass beds have been relatively well established as nutrient sinks. However, few studies have looked specifically at the concentration of heavy metals in seagrass bed sediment compared with adjacent bare sediment. This paper presents some preliminary findings for looking into the relationship of heavy metals in seagrass bed sediment compared with adjacent bare sediment within a temperate estuary of eastern Australia. Of the metals and elements tested, aluminium, barium, calcium, chromium, copper, iron, potassium, magnesium, manganese, sulphur and strontium were found in significantly higher concentrations within seagrass bed sediments compared to adjacent bare sediment. 2011-01-01T00:00:00Z http://hdl.handle.net/10453/19068 MODET - A modular model for estimating spatially distributed evapotranspiration, crop surface temperature and energy balance Punthakey Jf; Milne-Home William; Yunusa Isa; Theiveyanathan T; Prathapar Sa W. McLean & W.A. Milne-Home This paper describes a conceptnal framework for estimating spatially distributed evapotranspiration using a quasi two-layered resistance-energy balance model, which combines an energy balance equation for a crop surface and a modified Penman-Monteith combination equation. The modified equation allows estimation of transpiration from measured meteorological data and prescribed crop and soil parameters. The model predicts potential and actual evapotranspiration from a composite crop-soil surface by estimating components of the energy balance. The model requires hourly or daily averages of solar radiation, air temperature, humidity, and windspeed, along with estimates of canopy emissivity, albedo, crop height, and leaf area index. The model provides an analysis of the radiation and energy balance of the evaporation site, which includes net radiation, sensible, latent and soil heat fluxes. Canopy and leaf resistance, plant water potential and surface temperatures are also predicted by the model. These parameters estimate the response of the crop to enviromnentally induced water stress and can also be used as indicators for early warning of crop health. Modelled estimates of potential and actual evapotranspiration, crop surface temperature and plant water potential are presented for pasture in the Berriquin irrigation area. 2011-01-01T00:00:00Z http://hdl.handle.net/10453/19069 Performance Based Assessment of Dynamic Soil-Structure Interaction Effects on Seismic Response of Building Frames Fatahi Behzad; Tabatabaiefar Seyed Hamid Reza; Samali Bijan C. Hsein Juang; Kok Kwang Phoon; Anand J. Puppala; Russell A. Green; Gordon A. Fenton Soil-Structure Interaction (SSI) has progressed rapidly in the second half of 20th century stimulated mainly by requirements of the nuclear power and offshore industries to improve the seismic safety. In this study, a fifteen storey moment resisting building frame is selected in conjunction with three different soil deposits with shear wave velocity less than 600m/s. The design sections are defined after applying dynamic nonlinear time history analysis based on inelastic design procedure using elastic-perfectly plastic behaviour of structural elements. These frames are modelled and analysed employing Finite Difference approach using FLAC 2D software under two different boundary conditions, namely fixed-base (no soil-structure interaction), and considering soil-structure interaction. Fully nonlinear dynamic analyses under the influence of different earthquake records are conducted and the results of inelastic behaviour of the structural model are compared. Variations of the shear modulus ratio with the shear strain are included in the nonlinear dynamic analysis. The results indicate that the inter-storey drifts of the structural model resting on soil types De and Ee (according to the Australian standard) substantially increase when soil-structure interaction is considered for the above mentioned soil types. Performance levels of the structures change from life safe to near collapse when dynamic soil-structure interaction is incorporated. Therefore, the conventional inelastic design procedure excluding SSI is no longer adequate to guarantee the structural safety for the building frames resting on soft soil deposits. Design engineers need to address the effects of dynamic SSI precisely in their design especially for construction projects on soft soils. 2011-01-01T00:00:00Z http://hdl.handle.net/10453/19071 A comparison of deflation basin (wetland) soils from wet and dry climatic zones in Tasmania Neave Melissa; Rayburg Scott; Curtis Ellen N. Peters, V. Krysanova, A. Lepisto, R. Prasad, M. Thoms, R. Wilby, S. Zandaryaa Deflation basins, or shallow depressions formed by wind erosion, are found in many semi-arid regions around the world. Because these features are topographic lows they become sites of water accumulation and are often associated with wetlands that represent important refugia for biota in dry environments. Despite being important habitats little is known about the relationship between water and sediment in these features. This study assesses soil geochemical properties from 50 wet-climate and 39 dry-climate deflation basins in Tasmania. The results reveal clear differences between wet-climate and dry-climate deflation basin soils. Macronutrients typically have higher concentrations in wet-climate soils (with the exception of potassium and calcium) while metals and other trace elements typically have higher concentrations in dry-climate soils. These findings have important implications for wetland biological-soil associations, with high plant productivity likely in wet-climate deflation basins as a result of both favourable nutrient status and better water availability. 2011-01-01T00:00:00Z