Aqueous & Non-Aqueous Phase Tracer Migration Through Differing Soil Textures

The National Grid Transco Company sponsored this project in order to promote the understanding of NAPL migration through b-horizon soils and retarding effects upon non aqueous species migration. Soil structure and texture was also studied using conservative (Bromide) and non-conservative (Phosphate) tracers. Experimental data was produced using a laboratory ½ metre scale automated lysimeter designed and constn1cted at Plymouth. The tracers were compared before oil injection, to calibrate differences in soil texture, and after oil injection to detect any changes in the flow patterns caused by the oil injection. It was found that the Crediton, Sollom and Conway soils respectively offered least resistance to the tracers with the non-conservative tracer behaving much more unpredictably than the conservative tracer. After oil injection it could be seen that the oil had heavily retarded the ability of the tracers to migrate from the injection site. This retardation was identified as analogous to perturbations of the soil structure. Statistical analysis of the data showed that the experiments were all internally self consistent and visible patterns could be seen in the corrected data caused by inclusion of oil in the injection site. Methods of dispersal for the oil and tracer are suggested in the concluding chapter with references to the work of previous authors. Development of a hazard assessment framework was facilitated by the simulation of soil structures using a pedo transfer function developed at the National Soils Resource Institute. To allow the modelling of soils the Pore-Cor software had an annealed simplex algorithm integrated into the data inversion engine to allow the simulation of 3-D soil structures using 2-D data from pedo transfer functions or experimentally derived water retention curves. An extensive sensitivity analysis upon the model highlighted limitations, due to the data set the current pedo transfer function is based upon. It was suggested that inclusion of choices of different pedo transfer functions could be used to overcome this problem. A suitable framework was derived for the identification of priority soils using a validated computer model. Experimental data was compared to the simulated data in order to try and develop an understanding of practical upscaling of the data. The use of the "Scaleway" method is discussed in the concluding Chapter.Tbe National Grid Transco pl

The United Kingdom market for fresh exotic fruit (ODNRI Bulletin No. 13)

This bulletin examines the nature and structure of the United Kingdom market for fresh exotic fruit. Its findings relate primarily to six exotic fruit- avocados, pineapples, mangoes, paw paws, lychees and passion fruit - which are assumed to be a representative cross section of exotics in general. The major determinants of the level of exotic fruit consumption are analysed. Particular attention is focused upon the influence of prices and incomes and an attempt is made to obtain estimates of price and income elasticities of demand. The marketing channels through which imported fruit passes between importation and retailing are described, and the nature and functions of firms involved at each marketing stage are examined. Price formation and the transmission of information through the marketing chain between retailers, wholesalers, importers and exporters are discussed. The overall objective of the study is to provide information which will assist developing country exporters in identifying profitable trading opportunities within the market, and give some guidance for the design of their production and marketing strategies such that foreign exchange earnings are maximized

Derivation of physically based soil hydraulic parameters in New Zealand by combining soil physics and hydropedology

Field-characterised soil morphological data (to 1 m depth) and modelled soil water release characteristics are recorded in the S-map database for soils cover- ing approximately 40% of New Zealand's soil area. This paper shows the devel- opment of the Smap-Hydro database that estimates hydraulic parameters by synergising soil morphologic data recorded in S-map and soil physics. The Smap-Hydro parameters were derived using the bi-modal Kosugi hydraulic function. The validity of the Smap-Hydro parameters was tested by applying them within an uncalibrated physically based hydrological model (HyPix) and comparing results with soil water content, θ, measured with Aquaflex soil moisture probes (0–40 cm deep) at 24 sites across New Zealand. The HyPix model provided an excellent fit with observed soil water content for 25% of the sites, a good fit for 33% of the sites and a poor fit for 42% of the sites. Applying the model to all soils in the S-map database required adjustments for the occurrence of rock fragments, hydraulic discontinuities caused by soil pans and required the addition of boundary conditions for water tables and the occurrence of impermeable rock. A discussion on how we can further syner- gise the development of pedotransfer functions with knowledge of soil physics is provided

Storability of sweet potatoes (Ipomoea batatas (L.)) under tropical conditions: physiological and sensory aspects.

The shelf-life of the sweet potato storage root under tropical marketing conditions limits its potential for marketing. This research aimed to identify the physiological characteristics that affect the shelf-life of sweet potato cultivars when they are exposed to tropical marketing conditions. Weight loss was the key limiting factor in storability under the conditions studied. The range in weight loss was large amongst the 39 cultivars tested, and varied between 5 to 15% per week. Weight loss related to the marketable appearance. It consisted mainly of water loss and only 10% was due to respiratory metabolism. Sweet potatoes with high rates of water loss were more susceptible to rotting. The role of periderm characteristics (thickness and permeability), root-size, root surface area/mass ratio and shape were investigated. Although significant differences were observed among cultivars, these characteristics could not account for the variation in storability. The level of damage severely affected the rates of weight loss, with transpiration rate through damaged areas many times higher than through undamaged periderm. Breakage was found to be the most severe form of damage, having a great impact on weight loss for 14 days. Cultivars differed in susceptibility to damage after standardised damage treatments. Susceptibility to breaks was greater for long thin roots. Skinning injury was negatively related to the periderm thickness. Wound healing ability was a major factor for the shelf-life of sweet potato cultivars. It was demonstrated that lignification of wounds as measured by phloroglucinol staining, correlates with reduced susceptibility to weight loss, water loss and microbial attack. A lignin index was used to express the probability that lignification occurs. Cultivars differed significantly in their lignin indices under tropical marketing conditions. A high dry matter content generally coincided with a low lignin index. This relationship was consistent for 19 cultivars tested. Sensory evaluation of five sweet potato cultivars resulted in five distinct sensory profiles. During storage some of the cultivars lost some of their flavour but little changes were observed for textural properties. It was concluded that changes in sensory aspects are not a limiting factor for storage of sweet potato

Storability of sweet potatoes (Ipomoea batatas (L.)) under tropical conditions: physiological and sensory aspects.

The shelf-life of the sweet potato storage root under tropical marketing conditions limits its potential for marketing. This research aimed to identify the physiological characteristics that affect the shelf-life of sweet potato cultivars when they are exposed to tropical marketing conditions. Weight loss was the key limiting factor in storability under the conditions studied. The range in weight loss was large amongst the 39 cultivars tested, and varied between 5 to 15% per week. Weight loss related to the marketable appearance. It consisted mainly of water loss and only 10% was due to respiratory metabolism. Sweet potatoes with high rates of water loss were more susceptible to rotting. The role of periderm characteristics (thickness and permeability), root-size, root surface area/mass ratio and shape were investigated. Although significant differences were observed among cultivars, these characteristics could not account for the variation in storability. The level of damage severely affected the rates of weight loss, with transpiration rate through damaged areas many times higher than through undamaged periderm. Breakage was found to be the most severe form of damage, having a great impact on weight loss for 14 days. Cultivars differed in susceptibility to damage after standardised damage treatments. Susceptibility to breaks was greater for long thin roots. Skinning injury was negatively related to the periderm thickness. Wound healing ability was a major factor for the shelf-life of sweet potato cultivars. It was demonstrated that lignification of wounds as measured by phloroglucinol staining, correlates with reduced susceptibility to weight loss, water loss and microbial attack. A lignin index was used to express the probability that lignification occurs. Cultivars differed significantly in their lignin indices under tropical marketing conditions. A high dry matter content generally coincided with a low lignin index. This relationship was consistent for 19 cultivars tested. Sensory evaluation of five sweet potato cultivars resulted in five distinct sensory profiles. During storage some of the cultivars lost some of their flavour but little changes were observed for textural properties. It was concluded that changes in sensory aspects are not a limiting factor for storage of sweet potato

Influence of Algae on Soil Saturated Hydraulic Conductivity: An \u3ci\u3ein situ\u3c/i\u3e Treatment Option for Reducing Infiltration Beneath Unlined Algae Cultivation Ponds

Commercial production of algal biofuels is currently limited by high capital costs, including the cost of installation and maintenance of plastic pond liners, which mitigate seepage of cultivation fluids and control the release of salts and nutrients into the subsurface beneath outdoor algae cultivation ponds. However, studies of animal waste settling lagoons show that underlying soils ranging from sands to clay loams can exhibit reduced hydraulic conductivity within days to weeks after construction, reducing the need for plastic liners. The mechanisms of the hydraulic conductivity reductions, or “soil sealing”, are physical rearrangement of soil particles, buildup of fines, and the accumulation of microorganisms and their metabolic products within pore spaces. metabolic products within pore spaces. In this study, laboratory-scale soil column experiments investigated a new application for old technology by using fluids that are low-cost and readily available in algae biofuel production to reduce the saturated hydraulic conductivity (Ks) of soils of varying textures by promoting physical and microbial pore clogging mechanisms. Three fluid treatments were supplied to a fine sand soil 1) a nutrient solution used in commercial algae cultivation (NS), 2) the nutrient solution with glycerol added (NSG) and 3) algae (Scenedesmus dimorphus) growing in the nutrient solution (NSA). Relatively small reductions of Ks by NS (44-63%) indicate that the culture broth alone was insufficient to promote soil clogging. Larger reductions (77-94%) were seen by addition of the carbon substrate glycerol to the nutrient solution, indicative of enhanced bacterial growth. However, the Ks values produced by the NSG varied widely over time. The magnitudes of Ks reductions by NSA were also large (84-95%) and remained stable. The large, stable Ks reductions provided by algae, seen in the fine sand soil, were similar to those for a loamy sand (96-99%) and a loam soil (98%). The approximately two-order-of-magnitude Ks reductions imply that, like organic fines in animal waste holding ponds, algae can also significantly contribute to reductions in Ks of soils. This new technology appears to be successful in reducing the Ks of native soils and suggests the technology could be applied as an alternative to plastic liners

Mild processing of seafood—A review

Recent years have shown a tremendous increase in consumer demands for healthy, natural, high-quality convenience foods, especially within the fish and seafood sector. Traditional processing technologies such as drying or extensive heating can cause deterioration of nutrients and sensory quality uncompilable with these demands. This has led to development of many novel processing technologies, which include several mild technologies. The present review highlights the potential of mild thermal, and nonthermal physical, and chemical technologies, either used alone or in combination, to obtain safe seafood products with good shelf life and preference among consumers. Moreover, applications and limitations are discussed to provide a clear view of the potential for future development and applications. Some of the reviewed technologies, or combinations thereof, have shown great potential for non-seafood products, yet data are missing for fish and seafood in general. The present paper visualizes these knowledge gaps and the potential for new technology developments in the seafood sector. Among identified gaps, the combination of mild heating (e.g., sous vide or microwave) with more novel technologies such as pulsed electric field, pulsed light, soluble gas stabilization, cold plasma, or Ohmic heat must be highlighted. However, before industrial applications are available, more research is needed.publishedVersio