Spectroscopic Characterization of Dissolved Organic Matter Isolated From Solar Pond

Two-dimensional correlation spectroscopy (2D-COS) and three-dimensional excitation-emission matrix fluorescence technologies coupled with parallel factor analysis (EEM-PARAFAC) are characterized by separating overlapping peaks and insight into different component variations. Therefore, the 2D-COS and EEM-PARAFAC technologies can be used to probe into the compositions and spectral changes of dissolved organic matter (DOM). Here, the compositions and variations of DOM in solar ponds isolated from three representative salt lakes, i. e, Qarham Xitaijinaier and Mahai salt lake, were investigated using dissolved organic carbon UV-Visible absorption spectrum (UV) and EEM coupling with 2D-COS and PARAFAC. The results indicated that the contents of DOM and color DOM (CDOM) increased with the prolongation of sunshine times, and they increased 1. 5 vs. 1. 0, 8. 2 vs. 5. 3 and 15. 7 vs. 11. 0 times for DOM and CDOM they originated from Qarham Xitaijinaier and Mahai, respectively. Moreover, the values of SUVA254 and HIX decline in solar ponds suggested that the relative contents of aromatic compounds were decreased. The 2D UV-COS results indicated that the DOM with absorption peaks at 230, 217 and 235 nm were susceptibility in solar ponds, and following the sequence; 228>229>230>231>232 nm &235>234>233>232 nm, 200>216>300 nm and 201>203>231>232>237>238>281>217 nm for Qarham Xitaijinaier and Mahai, respectively. The EEM-PARAFAC results revealed that the salt lake DOM is mainly composed of four humic-like substances, i. e., marine humic-like component CDEx/Em: 320/400 nm), humic-like acids C2 (Ex/Em; 250/400 nm) and C3 (Ex/Em; 260/400 nm), hydrophobic humic acid C5 (Ex/Em: 280, 360/430 nm) and one protein-like substance C4 (Ex/Em; 280/350). The percentages of humic-like substances were 84. 0%, 87. 2% and 93. 1,y0 in total fluorescent contents in Qarham, Xitaijinaier and Mahai, respectively. Along with the sunshine extent, the relative contents of Cl C2 and C3 exhibited an initial decrease followed by a gradual decline or stabilization, especially C2 absence from the tail brine, indicating its lability. C3 and C4 exhibited an initially decrease, followed by the gradual increase in the solar ponds of Qarham and Mahai. Compared to other components, C3 and C4 were more refractory to degrade, i. e. 6. 7% <C3/C4<75. 2% vs. 52. 8% <C1/C2/C5<100%.