In coastal area, salinization is a common and serious problem for crop cultivation and ecological

Many lakes exist in southeastern Badain Jaran Desert and its hinterland, including 110 perennial lakes and some seasonal or extinct lakes. Geomorphological, sedimentological, and bioglyph evidence obtained from field investigations on Badain Jaran Desert lake group, alongside measurements and dating performed on lake relic, prove that these lakes expanded while the climate was relatively wet during early and middle Holocene. The dating results suggest that the pan-lake period of the Badain Jaran Desert began at 10 cal kyr BP, before which the limnic peat period occurred (11-10 cal kyr BP). Many lakes reached their maximal water-level during 8.6-6.3 cal kyr BP and retreated or dried up in the late Holocene (about 3.5-0 cal kyr BP). During that period, the precipitation at Badain Jaran Desert may have reached 200 mm yr 1 for 7.7-5.3 cal kyr BP, inferred from both the age and precipitation rate of calcareous root tubes. The water balance calculation shows that wetter and warmer climate and the increase of underground water recharge were key factors in maintaining and developing the lake group at both centennial and millennial time scales. Furthermore, lake surface expansion and the increasing fresh water availability set the background for the prosperous prehistoric culture.

No abstract

This study examined the bacterial and archaeal diversity from a worldwide range of wetlands soils and sediments using a meta-analysis approach. All available 16S rRNA gene sequences recovered from wetlands in public databases were retrieved. In November 2012, a total of 12677 bacterial and 1747 archaeal sequences were collected in GenBank. All the bacterial sequences were assigned into 6383 operational taxonomic units (OTUs 0.03), representing 31 known bacterial phyla, predominant with Proteobacteria (2791 OTUs), Bacteroidetes (868 OTUs), Acidobacteria (731 OTUs), Firmicutes (540 OTUs), and Actinobacteria (418 OTUs). The genus Flavobacterium (11.6% of bacterial sequences) was the dominate bacteria in wetlands, followed by Gp1, Nitrosospira, and Nitrosomonas. Archaeal sequences were assigned to 521 OTUs from phyla Euryarchaeota and Crenarchaeota. The dominating archaeal genera were Fervidicoccus and Methanosaeta. Rarefaction analysis indicated that approximately 40% of bacterial and 83% of archaeal diversity in wetland soils and sediments have been presented. Our results should be significant for well-understanding the microbial diversity involved in worldwide wetlands.