Seasonal and diurnal variations in dust characteristics on the northern slopes of the Tien Shan – Grain-size, mineralogy, chemical signatures and isotope composition of attached nitrate

摘要: Abstract A dust monitoring program was initiated in the summer of 2010 to (i) improve informative value aeolian components varved lake sediments Central Asia for palaeoclimatic interpretations, (ii) evaluate impact influx on modern lakes region and (iii) obtain data a future comparison with east high mountain belt formed by Alay, Pamir, Tien Shan Altai mountains. We collected coarse (>2.5 μm) fraction northern slopes 42°40′49.69″N, (74°41′37.36″E, 1740 m asl) using high-volume slit-impactor at 3-day sampling intervals. present mineralogical composition, particle-size distribution, soluble salts nitrate isotope composition dust. The short-term seasonal changes concentration are discussed context temporal resolution measurements meteorological parameters particle counts 31 grain-size bands. Throughout study period, CaCO3 major constituent (average frequency 14%). Between July October 2012, average content 10 wt.%; mole percentages water-leachable anions were 60% NO3, 30% SO4, 10% Cl. Ca dominant leachable cation (>90%). comprised gypsum which forms pedogenically topsoils arid regions secondary originating from interaction sulphuric acid aerosols atmosphere. Variable proportions extent Ca(NO3)2 formation (verified chemical mass budgets) documented Ca/Sr Ca/SO4 ratios aqueous leachates. isotopic compositions majority samples clustered between −10 +10‰ δ15N[NO3] (VSMOW) +50 +100‰ δ18O[NO3] (Air). values exhibited weak positive correlation NO3 load (R2 = 0.148). time series varied around basement level −6‰, indicates that NOx mobile sources is precursor dust-NO3. distinct, departures these correlated increases soot. conclude related peaks reflect increased contributions coal burning. possible origin evaluated satellite images backward trajectory calculations few example Data synthesis hemispherical atmospheric circulation models, including 2013, results ongoing analyses non-soluble solid residues materials statistical handling an extended set will further elucidate relationships involving circulation, load, characteristics region.