The Organic Geochemical Characteristics Of Total Nitrogen And Amino Acids In Different Salinity Water Of Qinghai, China

Nitrogen is a characteristic element that reflects the components and environment of salt lakes. Amino acids are important part of organics and organic nitrogen in salt lakes. The research of the total nitrogen and amino acids is highly significant in studying the salt lake environment and geochemical characteristics.By the determination of the total nitrogen content of inter-crystal brine in Bieletan and six different waters in southern Qinghai, it finds out that the nitrogen in Bieletan and Southern Qinghai are relatively higher. Total nitrogen content is less regular between different drill holes as well as the same drill hole with different depth. There are three trends that the total nitrogen content becomes larger, smaller and invariant with increasing depth, and the nitrogen content of drill holes which near Senie Lake and Xiaobiele Lake are lower than other areas. It may be influenced by the replenishment of Senie Lake and Xiaobiele Lake. The variation of total nitrogen content of inter-crystal brine in the area is not so influenced by factors such as common inorganic ion and degree of mineralization.By using HPLC, we tested the amino acids in inter-crystal brine of Bieletan Section. Referring to the result of total nitrogen in inter-crystal brine, we found that there exists a certain correlation between total nitrogen and amino acids in Bieletan Section, suggesting that in Bieletan Section, the index of total nitrogen makes some indicating significance for organic geochemistry.By testing amino acids of different salinity water in southern Qinghai we found amino acids in Bieletan Section are rather monotonous. Among the 17 common amino acids,only proline, methionine and arginine were found. So we inferred that the less biomass in high salinity water in this region and some kinds of amino acids rapid decomposition in inter-crystal brine are the main reason of this phenomenon. And the substantial presence of proline may be associated with the accumulation of proline inside living body under salt stress. Relatively speaking, the amino acids in different types of water in southern Qinghai are richer, and deferent from them in Bieletan Section,mainly serine,glycine, tyrosine, histidine and lysine. In terms of the total amount of amino acids, the amino acids in inter-crystal brine in Bieletan are higher than that in southern Qinghai. By researching the relation between degree of mineralization and amino acids in different salinity water in Southern Qinghai,we found in high degree of mineralizationn water, amino acids are relatively higher. With the increase of degree of mineralization amino acids will most likely increase. In a higher degree of mineralization in inter-crystal brine in Bieletan, it has higher amino acids. Judging from the nature of the amino acids, the generally high lysine and histidine in the samples in southern Qinghai are all basic amino acid, and the widespread proline and methionine in Bieletan are respectively nonpolar aliphatic amino acid and neutral amino acid. From the perspective of thermostability of the amino acids,among all the amino acids detected in the samples, it contains glycine which has preferably thermostability in water,asparagine and lysine which have moderate thermostability,serine, arginine and tyrosine which have relatively poor thermostability.