Aeolian Dust Inputs in the Mediterranean and Black Sea Marine System

<p>The aim of this paper is to estimate the amount of aeolian dust, deposited by dry and wet processes, that is deposited to the eleven marine regions of the Mediterranean-Black Sea Marine System (MBMS) and to compare it to the riverine influxes (i.e. suspended and dissolved sediment loads). This research is based on information for aeolian dust deposition at several coastal stations, around the MBMS, following an extended research of the available literature. For data elaboration, processing, and visualization a G.I.S. environment was utilized. The total annual amount of dust input for the whole system has been estimated to 59.9 × 106 tonnes, of which 57.2 × 106 tonnes are deposited in the Mediterranean Sea and only 2.7 ×106 tonnes in the Black Sea. The contribution of dust input (load), corresponding to 6.2% and 0.8% of the total amount of suspended and dissolved load, for the Mediterranean and Black Sea respectively, reveals the significant role of the aeolian dust inputs to the MBMS marine environment, in particular, at its southern Mediterranean domain.</p>

Luminescence sensitivity of German loess: indicators of source variability

&lt;p&gt;Loess &amp;#8211; a homogeneous, predominantly silt-sized aeolian sediment &amp;#8211; has long been recognised as a valuable terrestrial record of past environmental conditions. Loess deposits drape some 10% of the Earth&amp;#8217;s land surface, accumulating almost continuously in some regions. Most aeolian dust is thought not to travel far, often deriving from fine-grained material transported by rivers from glaciated regions. The provenance of loess sediment is inferred from the trajectories of atmospheric circulation systems and how these may have changed in intensity and influence over a region through time. The most frequently used techniques for correlating aeolian dust deposits with likely source areas, including bulk geochemistry, age distributions of detrital zircons, and Sr-Nd isotope ratios in clays, remain limited in the information they may provide about loess provenance. Since loess is dominated by silicate minerals &amp;#8211; namely, quartz and feldspars &amp;#8211; it is advantageous to explore their potential as indicators of source changes within loess-paleosol sequences (LPS). Increasingly, researchers have been exploring variations in the luminescence characteristics of sedimentary quartz and feldspar as possible provenance tools. Of a range of approaches so far applied, luminescence sensitivity is the quickest to measure and provides a means to rapidly assess potential changes in sediment source down LPS.&lt;/p&gt;&lt;p&gt;Luminescence sensitivity &amp;#8211; the signal intensity per absorbed radiation dose &amp;#8211; arises from the efficiency of charge traffic between traps and luminescence centres within a crystalline framework. In a sedimentary context, sensitivity is the product of interplay between source lithology and the history of the mineral in question. Consequently, shifts in sediment provenance may be observed through variations in luminescence sensitivity down LPS. Despite the presence of thick loess deposits across Europe, however, this approach has yet to be tested on this continent.&lt;/p&gt;&lt;p&gt;Here we undertake an empirical investigation of the luminescence sensitivity characteristics of quartz and feldspar from different grain-size fractions at the Schwalbenberg LPS in the German Rhine valley. The Schwalbenberg LPS has recently been shown to respond to variability in Atlantic-driven climate oscillations in fine detail; it follows, therefore, that changes in source will likely be recorded in its sediments. We test the potential of luminescence sensitivity as an indicator of changes in sediment source through time, comparing samples from a 30 m core (REM3) spanning the last full glacial cycle, with samples of oxygen isotope stage (OIS) 3-2 age exposed within a c. 6 m profile on the southern margins of the deposit. The temporal overlap of the two localities during OIS3 enables comparison of luminescence characteristics with respect to possible provenance during that timeframe; we find an inverse relationship between quartz and feldspar sensitivity, as well as variability in sensitivity between different quartz grain sizes. There is some indication that feldspar sensitivity increases during periods of soil formation down the core. These observations may suggest source variability over millennial timescales.&lt;/p&gt;

Aeolian dust sources, transport and deposition over the Chinese Loess Plateau during 1999-2019: A study using the FLEXDUST and FLEXPART models

&lt;p&gt;The aeolian dust deposits in the Chinese Loess Plateau (CLP) contain valuable information about past environmental changes in Asia. Unlocking this information requires knowledge on the Asian dust sources and dust transport mechanisms, and how the different source regions contribute to the total dust loading and deposition over the CLP.&amp;#160; By studying the dust transport and deposition under present day conditions using the Lagrangian Particle Dispersion model,&amp;#160; FLEXPART,&amp;#160; and the FLEXDUST dust emission model, we aim to better understand the dust signal in the Chinese loess records to constrain their interpretation as paleoclimate proxies.&amp;#160;&amp;#160;&lt;/p&gt;&lt;p&gt;Here we present results from a 20 year simulation of transport and deposition of aeolian dust over the CLP from 1999 until 2019, during the dust event season March until May. Both FLEXPART and FLEXDUST are driven by ERA5 ECMWF meteorological reanalysis data. FLEXPART is set up in a receptor oriented configuration, where many computational particles are released from the receptor points at each timestep. The computational particles are followed for 5 days backward in time probing for possible source regions. The end product is emission sensitivity, i.e. how sensitive the receptor is to emissions in possible source regions. The emission sensitivity establishes a linear relation between the source and receptor. Therefore, multiplying the emission sensitivity with the dust emission flux estimated by FLEXDUST produces a map of the source contribution for each receptor point. To investigate the difference in source regions between the fine and coarse dust, we include two particle sizes, 2 &amp;#956;m and 20 &amp;#956;m, in our simulation. The output from the model is compared against Asian polar vortex (APV) and Asian winter monsoon indices to identify how changes in the large scale atmospheric circulation affect the interannual variation of dust transport and deposition, and to determine whether the amount of deposited dust over the CLP is primarily governed by changes in the emission strength or by changes in the atmospheric circulation.&amp;#160;&amp;#160;&lt;/p&gt;