A one-year monitoring program from September 2009 to August 2010 for PM 10 was conducted at 8 monitoring sites in Tianjin, a coastal city in northern China. 24-hour PM 10 samples were collected every 6 days at each site. PM 10 samples were analyzed for elements, water soluble inorganic ions and carbonaceous species. This paper focused on the spatial and temporal variation of chemical composition and chemical mass closure of ambient PM 10 . Six categories were used to reconstruct PM 10 mass: crustal materials, trace elements, organic matter, elemental carbon, sea salt, and secondary inorganic aerosol. Crustal materials were the dominant fraction of PM 10 with annual average percentages varying from 31.6% to 33.8% of the total PM 10 mass. Secondary inorganic aerosol (non-sea salt sulfate, nitrate and ammonium) and organic matter were also major contributors to PM 10 , with annual mass fractions of 23.3% and 18.8%, respectively. In particular, non-sea salt-sulfate was the most predominant inorganic ion accounting for 47.9% of the category of secondary inorganic aerosol. Elemental carbon was a small category, accounting for 3.3%. Sea salt and trace elements contributed marginally to the PM 10 mass. The concentrations and mass fractions of crustal materials were generally highest in spring and lowest in summer while those of organic matter and secondary inorganic aerosol were generally highest in winter. Organic matter (P < 0.05) and elemental carbon (P < 0.001) concentrations showed significant spatial variations, and the concentrations were high at Beichen (BC) due to its proximity to the industrial zones and freeways. The concentrations of Ba, Zn, Pb, Sn, Sb were generally higher at BC and Hongqiao (HQ) than at other sites, suggesting higher influence of traffic emissions.

Ambient particulate matter with the aerodynamics diameter less than 10 μm (PM 10 ) was sampled in four northeastern Chinese cities (Shenyang, Anshan, Fushun and Huludao) , organic and total carbon were determined. In addition, chemical source profiles consisting of the same particulate components were obtained from a number of naturally occurring geological sources (soil dust from exposed lands and marine salt) and sources of atmospheric particulates resulting from human activities (construction derived dust, coal combustion fly ash, iron and steel manufacturing dust, zinc dust, vehicle exhaust, and sulfate). Chemical mass balance modeling (CMB) was applied to determine the particulate matter (PM) sources and their contributions to PM 10 in these four cities. The results showed that soil dust and coal fly ash were the major sources of ambient PM 10 in all four cities. The construction derived dust, iron and steel manufacturing dust also was the major source of PM 10 in Huludao, Anshan, respectively. Higher contribution of iron and steel manufacturing dust (33.3 μg/m 3 , 20.9%) in Anshan was observed in this study, compared with previous studies. The zinc dust was a special PM source of Huludao, with a contribution of 19.1 μg/m 3 (7.0%) to PM 10 .