Keith Gregson

Global carbon exchange and methane emissions from natural wetlands: Application of a process-based model

Wetlands are one of the most important sources of atmospheric methane (CH 4 ), but the strength of this source is still highly uncertain. To improve estimates of CH 4 emission at the regional and global scales and predict future variation requires a process-based model integrating the controls of climatic and edaphic factors and complex biological processes over CH 4 flux rates. This study used a methane emission model based on the hypothesis that plant primary production and soil organic matter decomposition act to control the supply of substrate needed by methanogens ; the rate of substrate supply and environmental factors, in turn, control the rate of CH 4 production, and the balance between CH 4 production and methanotrophic oxidation determines the rate of CH 4 emission into the atmosphere. Coupled to data sets for climate, vegetation, soil, and wetland distribution, the model was used to calculate spatial and seasonal distributions of CH 4 emissions at a resolution of 1° latitude x 1° longitude. The calculated net primary production (NPP) of wetlands ranged from 45 g C m -2 yr -1 for northern bogs to 820 g C m -2 yr -1 for tropical swamps. CH 4 emission rates from individual gridcells ranged from 0.0 to 661 mg CH 4 m -2 d -1 , with a mean of 40 mg CH 4 m -2 d -1 for northern wetland, 150 mg CH 4 m -2 d -1 for temperate wetland, and 199 mg CH 4 m -2 d -1 for tropical wetland. Total CH 4 emission was 92 Tg yr -1 . Sensitivity analysis showed that the response of CH 4 emission to climate change depends upon the combined effects of soil carbon storage, rate of decomposition, soil moisture and activity of methanogens.

Consumption of atmospheric methane by soils: A process‐based model

A process-based model for the consumption of atmospheric methane (CH4) by soils was developed to identify the most important factors affecting uptake rates and to determine whether the current uncertainties in the estimated size of the global soil sink might be reduced. Descriptions of diffusion and microbial oxidation processes, which together determine the CH4 flux, were included. The results suggest that the global sink strength lies within the range 20–51 Tg yr−1 CH4, with a preferred value of 38 Tg yr−1 CH4. Dry tropical ecosystems account for almost a third of this total. Here microbial activity rather than diffusion is limiting uptake. It is also in these areas that the impact of any intensification in agriculture will be the most pronounced, with a possible future reduction in uptake in excess of 3 Tg yr−1 CH4. This is in contrast to the overall impact of global warming, which is expected to leave the size of the global soil sink relatively unchanged.

Resolution improvement of ERS scatterometer data over land by Wiener filtering

Abstract Multiplicative Wiener deconvolution has been applied to ERS scatterometer measurements obtained over land with the aim of improving their spatial resolution. The ERS scatterometer was launched to provide high-accuracy radar backscattering measurements over the sea surface for the purpose of monitoring marine wind velocity. However, ERS scatterometer data soon inspired an increasing interest for land and sea ice monitoring. The main shortcoming of these applications has been the coarse resolution of the device. This varies between 25 km2 and 46 km2 before ground processing, which results in normalization down to ∼48 km2 so that all the measurements can be used jointly in the wind vector retrieval. Nevertheless, for the case of perdurable sea ice and land scenes, measurements with 25-km resolution before ground processing can be selected to form images. As will be shown here, this finer resolution can be recovered for these images by using a linear Wiener filter. This restoration technique was tested on a large scene from Russia. The improvement can be observed in the definition of the line of the river Obs basin.

Women Vegetarians LIFESTYLE CONSIDERATIONS AND ATTITUDES TO VEGETARIANISM

Describes an in‐depth study of the attitudes to food, food consumption patterns and health of young vegetarian women (aged 15‐30). Studies women as the ratio of female to male vegetarians is 2:1. Self‐completed questionnaires formed the basis of the study and provided information on length of time and degree of commitment to vegetarianism, affect on social relationships, and moral and health factors and food factors influencing the decision to become vegetarian. Food factors appeared to be less distinctive than moral and health factors. Concludes that more research is required, particularly into the strict vegan section of the population.

A survey of consumer awareness of salt in food and reported purchasing activity towards low salt foods

A MARKET research study of 160 adult respondents of both sexes subdivided into under-25 and over-25- year-old age groups was undertaken in Nottingham between January and April 1992. The aims of the study were to determine whether consumers per ceived salt in food as a health problem, their knowl edge of the salt content of selected foods, and whether they reported changes in purchasing ac tivity towards low salt food products. A high pro portion of respondents in this survey (83.8 per cent) believed salt to be detrimental to health but overall there was a poor level of knowledge of the salt con tent of a range of foods. Eighty-five per cent of re spondents had purchased reduced salt food products and 64.6 per cent of these had become regular users. Product development of actively promoted reduced salt foods offers potential, provided palatability and food safety problems are overcome.

Women's Attitudes to Slimming and Slimming Foods

With approximately 60 per cent of the adult female population in the UK (14.2 million women) slimming either seriously or as a token gesture, a survey of the attitudes of 200 women to slimming and slimming foods was conducted between October and December 1991 by either face‐to‐face interview or questionnaire in several East Midlands towns in England. Responses to questions were obtained on reasons for weight loss, whether medical advice was sought, how many calories gave steady weight loss, whether dieting took place at certain times of the year, whether women were satisfied with weight loss achieved, and reasons for dissatisfaction with weight loss. Further studies on attitudes to foods used in dieting were measured, in particular the use of “meal replacements”. Using rating scales the various meal replacements were categorized on the basis of cost, nutritional quality, ease of preparation, taste, satiety, variety and overall satisfaction. The study has shown the profile of the “typical” female dieter an...

CHILDREN′S VIEWS ON DAIRY PRODUCTS

A Survey among schoolchildren shows that while some of them believe we should eat less fat, they are unsure about how to achieve this. B.K.Lund, K. Gregson, R.J. Neals and C.H. Tilston describe their research.

The Meals on Wheels Service: A Consumer Survey

Combines a marketing study of the Meals on Wheels (MoW) service in Leicester, with a study of food consumption patterns in 1,500 elderly persons by the use of a self‐completed questionnaire, which aimed to evaluate the consumer characteristics, service provision and degree of satisfaction of MoW recipients and identify specific areas of dissatisfaction. Overall 88 per cent said they were very satisfied or satisfied with the service. Food consumption patterns showed that the majority of the elderly ate other food besides MoW but 26 per cent of recipients provided no information, suggesting that little other food was eaten. Further research is required on preference ratings for various types of meals and on the attitudes of the elderly to certain food types, e.g. fruit, vegetables, milk and other dairy products.