A High‐resolution Atmospheric Dust Record for 1810–2004 A.D. Derived from an Ice Core in Eastern Tien Shan, Central Asia

Centennial‐scale, high‐resolution records of atmospheric dust conditions are rare in the arid and semiarid regions of central Asia, limiting our understanding of the regional climate and environmental changes and their potential driving forces. In this paper, we present an annually resolved atmospheric dust record covering the period of 1810–2004 A.D., reconstructed from an ice core retrieved at 4512 m above sea level from the Miaoergou Glacier in the eastern Tien Shan. The time series of dust flux for the past 195 years shows three periods of relatively low values (i.e., 1810–1829 A.D., 1863–1940 A.D., and 1979–2004 A.D.) and two periods of relatively high values (i.e., 1830–1862 A.D. and 1941–1978 A.D.). Spatial correlation analysis suggests possible regional factors controlling the dust flux, including antecedent summer precipitation, spring soil moisture, and near‐surface wind speed. In addition, the Miaoergou dust flux is closely associated with the winter index of the North Atlantic Oscillation (NAO) over the past two centuries, with high (low) dust periods coinciding with the negative (positive) phases of the NAO. The persistent relationship suggests that the NAO may have been a key driver on dust flux change over the arid regions between the Tien Shan and Kunlun Mountains

Possible Recent Warming Hiatus on the Northwestern Tibetan Plateau Derived from Ice Core Records

Many studies have reported enhanced warming trend on the Tibetan Plateau (TP), even during the warming hiatus period. However, most of these studies are based on instrumental data largely collected from the eastern TP, whereas the temperature trend over the extensive northwestern TP remains uncertain due to few meteorological stations. Here we combined the stable isotopic δ18O record of an ice core recovered in 2012 from the Chongce glacier with the δ18O records of two other ice cores (i.e., Muztagata and Zangser Kangri) in the same region to establish a regional temperature series for the northwestern TP. The reconstruction shows a significant warming trend with a rate of 0.74 ± 0.12 °C/decade for the period 1970–2000, but a decreasing trend from 2001 to 2012. This is consistent with the reduction of warming rates during the recent decade observed at the only two meteorological stations on the northwestern TP, even though most stations on the eastern TP have shown persistent warming during the same period. Our results suggest a possible recent warming hiatus on the northwestern TP. This could have contributed to the relatively stable status of glaciers in this region

Enhanced Recent Local Moisture Recycling on the Northwestern Tibetan Plateau Deduced From Ice Core Deuterium Excess Records

Local moisture recycling plays an essential role in maintaining an active hydrological cycle of the Tibetan Plateau (TP). Previous studies were largely limited to the seasonal time scale due to short and sparse observations, especially for the northwestern TP. In this study, we used a two‐component mixing model to estimate local moisture recycling over the past decades from the deuterium excess records of two ice cores (i.e., Chongce and Zangser Kangri) from the northwestern TP. The results show that on average almost half of the precipitation on the northwestern TP is provided by local moisture recycling. In addition, the local moisture recycling ratio has increased evidently on the northwestern TP, suggesting an enhanced hydrological cycle. This recent increase could be due to the climatic and environmental changes on the TP in the past decades. Rapid increases in temperature and precipitation have enhanced evaporation. Changes of land surface of plateau have significantly increased evapotranspiration. All of these have intensified local moisture recycling. However, the mixing model used in this study only includes a limited number of climate factors. Some of the extreme values of moisture recycling ratio could be caused by large‐scale atmospheric circulation and other climatic and weather events. Moreover, the potential mechanisms for the increase in local recycling need to be further examined, since the numeric simulations from climate models did not reproduce the increased contribution of local moisture recycling in precipitation

A Protective Role of Phenylalanine Ammonia-Lyase from <i>Astragalus membranaceus</i> against Saline-Alkali Stress

Phenylalanine ammonia-lyase (PAL, E.C.4.3.1.5) catalyzes the benzene propane metabolism and is the most extensively studied enzyme of the phenylpropanoid pathway. However, the role of PAL genes in Astragalus membranaceus, a non-model plant showing high capability toward abiotic stress, is less studied. Here, we cloned AmPAL and found that it encodes a protein that resides in the cytoplasmic membrane. The mRNA of AmPAL was strongly induced by NaCl or NaHCO3 treatment, especially in the root. Overexpressing AmPAL in Nicotiana tabacum resulted in higher PAL enzyme activities, lower levels of malondialdehyde (MDA), and better root elongation in the seedlings under stress treatment compared to the control plants. The protective role of AmPAL under saline-alkali stress was also observed in 30-day soil-grown plants, which showed higher levels of superoxide dismutase (SOD), proline, and chlorophyll compared to wild-type N. Tabacum. Collectively, we provide evidence that AmPAL is responsive to multiple abiotic stresses and that manipulating the expression of AmPAL can be used to increase the tolerance to adverse environmental factors in plants