Discussion of “Natural Indicators of Estuarine Sediment Movement”

Natural trace metal concentrations in estuarine and coastal marine sediments of the southeastern United States

“…This is particularly true in the coastal regions of the southeastern United States where natural estuarine and nearshore sediments are composed of trace-metal-poor phases (e.g., fineto coarse-grain carbonates and quartz sands), and metal-rich phases in mixtures depending on local natural sources. The most important natural metal bearing phases in these sediments are the clay minerals smectite and kaolinite (1,2). Since the metal-rich aluminosilicates (i.e., clays) are associated with the fine-grain fraction of sediments, the grain size distributions along with sediment source become the most important factors influencing natural metal concentrations.…”

Deliquescence Behavior of Internally Mixed Clay and Salt Aerosols by Optical Extinction Measurements

“…In this paper, we investigated the optical properties of AS and NaCl mixed with montmorillonite [(Na,Ca)(Al,Mg) 6 (Si 4 O 10 ) 3 (OH) 6 ], a common component of mineral dust originating from specific source regions like the Northern Sahara and southern United States. 30,31 Our montmorillonite sample originated in Gonzales County in Texas. Mineral dust aerosol is associated with windblown dust soil and has an estimated global source strength of 1000−5000 Tg year −1 , accounting for 45% of the total aerosol mass load.…”

“…There have been few direct studies on the optical properties of complex aerosol mixtures. − Recent studies have used models to approximate the effects using volume-weighted mixing rules, which assume minimal dependence on mixing state. ,,,− These studies of internal mixtures show good agreement between theory and experiment if each component in the mixture behaves independently in terms of water uptake. In this paper, we investigated the optical properties of AS and NaCl mixed with montmorillonite [(Na,Ca)(Al,Mg) 6 (Si 4 O 10 ) 3 (OH) 6 ], a common component of mineral dust originating from specific source regions like the Northern Sahara and southern United States. , Our montmorillonite sample originated in Gonzales County in Texas. Mineral dust aerosol is associated with windblown dust soil and has an estimated global source strength of 1000–5000 Tg year –1 , accounting for 45% of the total aerosol mass load. ,, Mineral dust is mixed with soluble species like AS and NaCl by coming in contact with sea salt particles during in-cloud processing or through condensation of compounds onto the particle surface with up to 85% of transported dust being internally mixed with other material. − Generally, the effect of RH on the radiative properties of mineral dust is considered negligible as the particles are treated as nonhygroscopic .…”