Framing the search for a theory of land use

ABSTRACT

Land system science and affiliated research linked to sustainability require improved understanding and theorization of land and its change as a social-ecological system (SES). The absence of a general land-use theory, anchored in the social subsystem but with explicit links to the environmental subsystem, hampers this effort. Drawing on land-use explanations, meta-analyses, and associated frameworks, we advance a broad framework structure of eight elements – aggregations of explanatory variables – with links to the biophysical subsystem, for systematic comparisons of extant explanations. Tests and models can be employed to identify which set of variables and their configurations provide robust explanations of across land uses, identifying the potential for theory development. The framework and its application are applicable to both top-down and bottom-up explanatory approaches employed in the social sciences. Links to the environmental subsystem invite future exploration of SES explanations that reach across the different dimensions of global change and sustainability science.     

Characterization of individual aerosol particles in workroom air of aluminium smelter potrooms

Aerosol particles with aerodynamic diameters between 0.18 and 10 microm were collected in the workroom air of two aluminium smelter potrooms with different production processes (Soderberg and Prebake processes). Size, morphology and chemical composition of more than 2000 individual particles were determined by high resolution scanning electron microscopy and energy-dispersive X-ray microanalysis. Based on chemical composition and morphology, particles were classified into different groups. Particle groups with a relative abundance above 1%(by number) include aluminium oxides, cryolite, aluminium oxides-cryolite mixtures, soot, silicates and sea salt. In both production halls, mixtures of aluminium oxides and cryolite are the dominant particle group. Many particles have fluoride-containing surface coatings or show agglomerations of nanometer-sized fluoride-containing particles on their surface. The phase composition of approximately 100 particles was studied by transmission electron microscopy. According to selected area electron diffraction, sodium beta-alumina (NaAl(11)O(17)) is the dominant aluminium oxide and cryolite (Na(3)AlF(6)) the only sodium aluminium fluoride present. Implications of our findings for assessment of adverse health effects are discussed.