START FELLOWSHIP PROGRAMME IN THE MEDITERRANEAN AND AFRICA

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Team MEDIAS-FRANCE in 1998 Mrs Abigail MAISSAH-ARTHUR stands on the extreme left

Mrs Abigail AMISSAH-ARTHUR, from Nigeria, was awarded a START fellowship from July to December 1998. Her fellowship was then complemented by the French space agency, CNES in order to let her go on working until June, 1999. During these two periods, she worked with researchers under MEDIAS-France co-ordination to correlate remotely sensed data of land cover change with biophysical and socio-economic information for the African Sahel. From July 1998 to July 1999, Mrs. Amissah-Arthur took short courses at the GDTA in image processing, and worked with CESBIO, "Centre d'Etudes Spatiales de la Biosphère" - Centre for Study of Biosphere from Space (B. MOUGENOT, IRD). Mrs. Amissah-Arthur had access to datasets from the Hapex-Sahel, SALT experiments and the ROSELT network (Banizoumbou site, Niger) which enabled her to address two emerging issues of importance not only in Africa but most developing countries. These issues include:

• Merging satellite based maps of land cover change with biophysical and census based indicators of socio-economic and demographic structure for assessment of various environmental issues;
• Impacts of agriculture on soil degradation. This problem receives increasing attention in regional and internationalinstitutions, particularly in the Sudano-Sahelian or sub-Saharan Africa where cropland and rangeland are most threatened.

Results confirmed that agricultural land degradation had set in due to increasing pressure of population and agricultural expansion in a system characterised by little or no inputs use. 56% of the study area currently supports a population density higher than the carrying capacity. 63% of the study area is under early to late phases of agricultural intensification. Between 1986-96, cultivation declined 2-3% annually on landscapes with low risk of degradation but increased 1-2% on those with average to extreme risks. This demonstrates the process of land abandonment as farmers move on to cultivating marginal lands despite normal seasonal rainfalls observed during most of the period. By 1996, cultivation tended to include fields much farther away from the village vicinities compared with 10 years earlier. Furthermore, by 1996, farmlands in the zones of late intensification declined from 12 to 4% and increased from 6 to 11% in the zone under the expansion phase, indicating that a substantial amount of the land area required increasing lengths of following. The spatial GIS modelling approach allowed not only identification of zones, but synthesis of the observed pattern of landscape degradation. These quantitative figures have to be considered cautiously, taking into account the uncertainty in classification processes; however, the overall identified evolution appears as significant. A scientific paper will be submitted for publication in a peer-reviewed journal, highlighting the need for combining remote sensing, biophysical and socio-economic data in environmental degradation studies in developing countries and map the results.

The study stressed the necessity of developing countries scientists taking the forefront to tackle environmental problems that affect their region. Many scientists from these regions are working or have worked on some of the issues at local scales and thus possess baseline data and information required for vulnerability and risk assessment. However, such assessments also require long-term observational systems and trend analysis possible only through the use of satellite derived information to which many developing countries do not have access. Hence, closer collaboration needs to be encouraged between developing country scientists and organisations in charge of setting up regional and global databases such as the MEDIAS-France and CIESIN. Such collaboration is possible through international research networks such as the START and the IGBP/IHDP land use/cover projects. In the longer run, through accumulated knowledge enabling comparative studies, it would be possible to develop a better understanding of the relationships among demographic dynamics, technology, cultural behavioural norms, and land resources. This requires strengthened interdisciplinary research, emphasising community-level experience. Although conducted at a local landscape level, the methodology, in connection with other researches on these issues, can be applied at a regional scale. Results show interactions between socio-economic and environmental factors that can help governments and policy-makers to assess the scope of the problem, examine alternatives, and decide on a course of action.

Mr Mustafa KOCAK is presently with the Middle East Technical University, Institute of Marine Sciences (IMS-METU), Chemical Oceanography Department, Erdemli-Içel, TURKEY. In 1999, he successfully applied to a START for a fellowship to work in the department of chemistry, school of Science of the University of Crete, under supervision of Dr. N. Mihalopoulos.
The overall goals of the atmospheric research program undertaken at IMS-METU are to develop a fundamental understanding of the processes that determine atmospheric composition, to understand the interactions between atmospheric chemical composition and physical, biospheric and climatic processes, and to predict the impact of natural and anthropogenic forcings on the chemical composition of the atmosphere. Efforts are dedicated to understanding this complex system through a combination of observations, theory, and laboratory and modelling studies. The first step was accomplished as to characterise the regional and temporal distribution of aerosol properties (prevailing meteorology leading) to long range transport of Sahara dust to the region.

Results from investigations led by IMS-METU since 1992 revealed findings that the impact of atmospheric pollution is less in the eastern Mediterranean atmosphere than in western Mediterranean. In the spring time periods the major aerosol component of the eastern Mediterranean atmosphere is the mineral aerosol transported from the North African deserts. Another important and interesting result of the aerosol study is the high concentration of sulphate aerosols. At this stage it is not understood whether the high amount of sulphate aerosols are originated from pollution or biogenic sources.

Aerosols have many different sources that spread around the globe. Each of these sources produces aerosols with specific chemical and physical properties, which make them behave all differently in the atmosphere. The international community of aerosol researchers has therefore planned a series of three Aerosol Characterisation Experiments (ACE) that took place in different areas on the globe, each addressing a specific type of aerosol. All these experiments have been designed by a group of scientists within the International Global Atmospheric Chemistry (IGAC) project, which is a core project of the International Geosphere-Biosphere Programme (IGBP). IMS-METU ultimate aim is to convince the atmospheric research groups around the Mediterranean region to prepare a research proposal for a possible ACE-4 campaign that would be conducted in the Mediterranean atmosphere. The IMS-METU atmospheric research program predominantly sponsored by Turkish Scientific and Research Council represents a prototype of ACE experiments.

Mr Mustafa Koçak is performing trace metal analysis of the daily aerosol samples collected at the sampling tower located at the institute for the years of 1996, 1997 and 1998. Three-dimensional, 3-day back trajectories, arriving at the sampling point at 12 UT at levels of 900-, 850-, 700- and 500- hPa have been computed, based on the operational model results at ECMWF (Reading, England). Utilising trace metal composition of aerosols together with air mass back trajectories he should be able to study potential source regions which affect trace metal composition of aerosols over the eastern Mediterranean. Concentrations of the major soluble ions: sulphate (SO42-), nitrate (NO3-), chloride (Cl-), methane-sulfonate (MSA), sodium (Na+), ammonium (NH4+), potassium (K+), calcium (Ca++) and magnesium (Mg++) will be measured on the same samples at the Department of Chemistry, University of Crete under the supervision of Dr Nikos Mihalopoulos who is the one of the leaders on the subject. SO42- aerosols in the atmosphere can have mixed origin (marine and anthropogenic). Assuming that all measured Na+ has a marine origin, the sea spray contribution to the observed concentrations can be calculated. MSA is an oxidation product of biologically produced dimethlysulfide (DMS). MSA concentrations are generally used to evaluate the contribution of the marine source to the sulphur budget of the atmospheric aerosols. Based on the measured MSA concentrations, a picture of the relative contribution of biogenic and anthropogenic sources to the sulphur cycle in the east Mediterranean region can emerge. MSA produced from the oxidation of dimethylsulfide (DMS) has exclusively biogenic origin. Non-sea salt sulphate is partly formed by DMS oxidation. Thus, if the molar ratio of MSA/nss- SO42- from this biogenic source is known, then the parts of nss- SO42- originating from biogenic and anthropogenic sources can be calculated. This would lead to assessment of the relative importance of factors controlling the aerosol composition in the eastern Mediterranean.

Mr Mustafa Koçak's visit will also:

• Enhance the exchange of data and communication of regional research results concerned with global change;
• Generate results leading to a joint publication;
• Lead to further collaboration on regional research effort.

Pr. MIHALOPOULOS
Department of Chemistry
University of Crete
Dios 9
71305 Keraklion (Greece)