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Atmospheric particulate matter (PM) from multinatural and anthropogenic sources poses serious risk to human health and contaminates soil and water resources as it settles back to ground environment and ecosystem. In this study, dust deposition flux (DDF), pollution load index (PLI) of heavy metals, enrichment factor (EF), and settling flux (SF) of eighteen chemical elements were investigated in comparison with crustal composition to assess the influence of anthropogenic emission on PM in major northern Chinese cities. The annual DDF in Lanzhou, Huhhot, Beijing, Zhengzhou, and Harbin was 134.7, 240.6, 103.7, 124.7, and 196.7 g m, respectively. The annual EF of Zn in Harbin, Cd in Lanzhou, and Cd in Beijing was 736.4, 248.6, and 166.3, respectively. Most of the inspected elements were enriched during winter in Lanzhou. Annual PLI showed that deposited dust in Beijing had the highest concentration of heavy metals. Seasonal PLI exhibited obvious changes in different cities. The annual SF of crustal elements was 1-5 orders higher than that of heavy metals. The highest annual SF of elements was identified mainly in Lanzhou and Huhhot. Sulfur, cadmium, copper, lead, and zinc in the dustfall of most urban areas were from human activities. Fossil fuel burning, metal smelting, mining, construction, and vehicle exhaust are the major sources of enriched elements in dustfall in urban areas of northern China. Toxic pollutants with dustfall are widespread and persistent, which deserves public concern in future sustainable development. [ABSTRACT FROM AUTHOR]

As in other parts of the world, air pollution over West and Central Africa has major health and meteorological impacts. Air quality assessment and its possible sanitary impact have become essential even in medium-sized towns, therefore amplifying the need for easy-to-implement monitoring methods with low environmental impact. We present here the potential of magnetic methods to monitor air quality at street level in the medium-sized city of Maroua (northern Cameroon) affected by dust-laden desert winds. More than five hundred (544) samples of bark and leaves taken from Neem trees in Maroua were analyzed. Magnetic susceptibility, saturation remanence, and S-ratio were found to determine the concentration and nature of magnetic particles. They are dominated by magnetite-like particle signals as a part of particulate emissions due to urban activities, including both traffic, composed of a substantial proportion of motorcycles, and wood burning for food preparation. We show that both bark and leaves from Neem trees are adequate passive bio-recorders. The use of both enables different times and heights to be sampled, allowing for the high-resolution monitoring, in terms of spatialization, of various urban environments. Particle emissions require assessment and screening that could be carried out rapidly and efficiently by magnetic methods on bio-recorders, even in cities impacted by dust-laden wind. [ABSTRACT FROM AUTHOR]