Mixing depth

Produce the densest ballasts observed In sinking particles destroyed in regions where the mixing depth of the ocean is below the euphotic zone. Their calcification rate is reduced at low pH. Zn limited... 

Holzworth, G. C. Mixing depths, wind speeds, and air pollution potential for selected localities in the U.S. Appl. Meteorol. 6 1039 (1967). 

Even taken qualitatively, these reactivity data have important toxicological as well as chemical implications regarding the composition of PAHs and PACs in and on the surfaces of aerosols in polluted air parcels, both near-source and during transport (downwind). Thus, under certain conditions (e.g., daytime, summer season, and high oxidant levels) over a period of hours BaP concentrations in ambient air could be expected to decay dramatically as a result of reactions, while those of the benzofluoranthenes and indeno[l,2,3-cabsolute concentrations also change as a result of dilution of the air parcel caused by increased mixing depth over time and transport. However, impacts of such physical processes are minimized if one considers ratios of concentrations of reactive to nonre-... 

The physical effect of dilution of the aerosols due to increased mixing depths during transport of the air parcel inland is factored out by taking the ratios of the concentrations at Claremont to those at central Los Angeles. As seen in Table 10.32, the ratios are 0.21 and 0.20 for the low-reactivity PAHs benzo[k](luoranthene and i nde no[ 1,2,3-cd ]pyrene (Class V, Table 10.30), reflecting dilution, whereas the ratios are 0.10 and 0.03 for reactive BaP and cyclopenta[cd ]pyrene (Class II), respectively, indicative of reactions in addition to dilution. 

The vertical profile of DMS in marine air was first determined by Ferek et al (12), over the tropical Atlantic ocean. They found that under stable meteorological conditions, the mixing depth of DMS was about 1 km, with a rapid decline in concentration above this altitude. This distribution was considered consistent with the chemical lifetime of a few days predicted by... 

Figure 7.20 A dual-tracer approach (using both 137Cs and 210Pb) in sediment cores collected from lower Chesapeake Bay (USA). The maximum depth of 137Cs was used to corroborate the physical mixing depths established with excess 210Pb. = excess activity A = total activity. (Modified from Dellapenna et al., 1998.)...

Mixing depth depth that is actively mixed in surface waters corresponding to the depth in which there is strong turbulence which is driven by surface forcing. 

Boudreau B. P. (1998) Mean mixed depth of sediments the wherefore and the why. Limnol. Oceanogr. 43,... 

Argyria and hepatotoxicity has been reported after the use of a silver-coated wound dressing, Acticoat, in the treatment of 30% mixed depth bums in a 17-year-old boy (21). Silver concentrations were high in the plasma (107 pg/kg) and urine (28 pg/kg). 

The height of the PBL, which is also sometimes known as the mixing depth (Arya 1999), is set by the presence of a stable layer that in effect caps the PBL, suppressing further vertical transport of dispersing species to greater elevations. In other words, the dispersing species will be essentially confined within the PBL by... 

Hanna, S.R. and Yang, R., 2000. Evaluation of mesoscale models simulations of near-surface winds, temperature gradients, and mixing depths, J. Appl. Meteorol., 39, pp. 1095-1104. 

Figure 5. Results of a model for inhibition of photosynthesis in the surface layer of the Weddell-Scotia Confluence of the Southern Ocean (modified from Neale et al. [70]). (a) Interactive effects of mixing depth and mixing time scale on daily water column productivity relative to the uninhibited rate (curves labeled with t ,ix = time scale of mixing). Langmuir circulation can mix the upper water column rapidly, so mixing times < 1 h are modeled for mixing depths <42 m. (b) Interactive effects of O3 depletion (150 DU vs 300 DU) and mixing time as a function of mixing depth proportional change in Pj for the same curves as in (a).

Figure 6. Effects of UVR on photosynthesis (total C assimilation) of phytoplankton moved through different mixing depths, presented as per cent photosynthesis in quartz (UVR transparent) relative to glass (partial UVR exclusion) bottles. Measured rates are for bottles that were circulated over the indicated depth ranges at the rate of once per 4 min (0-2 m), once per 8 min (0-3.9 m) and once per 20 min (0-10 and 0-14 m) for a 4 h midday incubation period. The modeled rates are the average of the steady-state (irradiance based) photosynthesis predicted using a biological weighting function and photosynthesis irradiance (BWF/P-I) curve applied to in situ irradiance estimated from recorded surface irradiance, depth of the bottles and measured vertical extinction coefficient. Model and measurements agree within measurement variability (ca. 10%) except for the 0-10 m incubation. Experiments were conducted in Lake Lucerne on September 13,1999 (no asterisks) and September 15,1999 (asterisks, see exposure data in Figure 2). [Modified from Kohler et al. 79.]...

E.J. Fee, R.E. Hecky, S.E.M. Kasian, D.R. Cruikshank (1996). Effects of lake size, water clarity, and climatic variability on mixing depths in Canadian shield lakes. Limnol. Oceanogr., 41, 912-920. 

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