Estimates of asteroid impact frequency in the Black SeaĪ rough estimate for the impact frequency as a function of impactor size is given by Chapman et al. They refer to hydrogen sulfide vertical distribution measured on 9 August 1989 at station 4133 (43☂0′N, 36☁0′E sea depth: 2163 m) and on 7 November 1993 at the above-mentioned station 4010.ģ. Data reported in Figure 3 of Neretin and Volkov ( Neretin and Volkov 1995) are used in this paper. Studies of the hydrophysical and hydrochemical particularities of the deep water of the Black Sea are scarce due to the rather poor hydrophysical database. They refer to the seawater vertical temperature distribution measured on 7 November 1993 at station 4010 (43☃0′N, 31☄5′E sea depth: 1910 m). Data reported in Figure 1 of Neretin and Volkov ( Neretin and Volkov 1999) are used in this paper. 1997).īoth the salinity and the potential temperature increase with depth in the Black Sea waters. Some authors believe that due to human interventions (dams on rivers pollution of the seawater) this surface layer may become thinner in the future, resulting in H 2S bubbles entering the atmosphere (e.g., Humborg et al. The surface layer is mostly generated by rain and freshwater inputs from rivers. The Black Sea is Earth’s biggest reservoir of hydrogen sulfide, which is generated by bacterial reduction of sulfate both in the water column and in the Holocene seafloor sediments ( Schuiling et al. About 87% of its volume below a surface layer of thickness 150–200 m is anoxic and therefore lifeless except for anaerobic bacteria. It has a surface area of 422 000 km 2, a coastline length of 4090 km, and a maximum water depth of about 2200 m. ![]() The Black Sea ( Figure 1) is situated at 40★5′–46☃2′N latitude, 27☂7′–41☄2′E longitude. Consequences of nuclear explosions in the deep seawater of the Black Sea are briefly discussed at the end of the paper. The effects of the poisoning gas on the population are briefly compared with the effects of shock waves and tsunamis. Estimates for the number of people living on or near the seashore that may be affected by the poisonous gas are performed. Different asteroid sizes are considered and various impact positions near the western coast of the Black Sea are taken into consideration. Two different mechanisms of hydrogen sulfide cloud formation are proposed. In this paper we improve our previous model and a much more detailed analysis is performed. A scenario concerning the consequences of a not very large asteroid impacting the Black Sea was presented by us (Schuiling et al. An additional poisonous effect may be associated with impacts in the Black Sea, the largest anoxic water body on Earth. The usual effects of asteroid impacts on water are atmospheric shock waves and tsunamis. ![]() Recently, a number of researchers have argued that a fourth size range should be added, namely, (iv) multi-ten-meter impactors like Tunguska ( Foschini 1999, and reference therein Jewitt 2000). 1997): (i) regional disasters due to impacts of multi-hundred-meter objects (ii) civilization-ending impacts by multikilometer objects and (iii) Cretaceous–Tertiary-like (K/T for short) cataclysms that yield mass extinctions. The environmental consequences from impacts are usually classified in three size ranges ( Toon et al. The impact hazard from extraterrestrial bodies tends to evolve in the recent years from a pure scientific problem toward a serious societal issue. Nuclear explosions of 1 and 50 Mton TNT may be assimilated to the impact by asteroids of about 33- and 120-m diameter, respectively. These effects are briefly compared with more usual effects associated with asteroids impacting the sea, such as shock waves and tsunamis. The evaluations do not include the population of the towns on the seashore and may be a few times underestimated for some particular wind directions. In the case of a 70-m-sized asteroid, the cloud covers between 70 and 210 km 2 of land. ![]() The land surface area covered by the H 2S cloud generated by a 1000-m-sized asteroid during the run-in ranges between about 44 km 2. The wind speed plays an important role in H 2S cloud dynamics. Two simple models are proposed to describe the generation of the H 2S cloud. Some effects of this phenomenon on the western Black Sea coasts are evaluated in this paper. ![]() The impact of an asteroid or a very large nuclear explosion in the Black Sea may cause a poisonous hydrogen sulfide gas release into the atmosphere.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |