石羊河流域初春和仲夏两委不同地点，洪水期、平水期30个河水样孢粉分析显不，没有人类影响的情况下，河水样孢粉组合是由河流上游径流区的植物孢粉和采样点附近植被孢粉组成的，前者的在孢粉组合中至少占30%～60%。河水搬运孢粉的能力非常强，可长距离、大量地搬运孢粉。孢粉组合中河水贡献孢粉的合量较高，如：云杉属（Picea Dietr.）花粉河水的贡献率在中下游可达16.5～7.7%。采样时间、地点影响河水的孢粉组合和浓度，洪水期是孢粉搬运的主要时期。河水经过水库后，其中孢粉绝大多数沉积在水库中。

The loess/paleosol sequence in loess layer L1 (Malan Loess) is invesitgated in three regions of the Western Chinese Loess Plateau, Nine pedogenic layers are found n L1 and three proxy climate indices, magnetic susceptibility (MS), grain size (GS) and CaCO3 content, are measured at intervals of 0.2 kyr in order to recover records of monsoon climate variations. Time series of MS, GS and CaCO3 content document the ghigh resolution history of summer and winther monsonn climate variations over the last 75 kyr. The records show a high degree of similarity to the warm interstadials recorded in ice cores from Greenlandand the Antarctic, and with Heinrich events in the North Atlantic, during the last glacial cycle. Bond cycles are also recorded by the Chinese loess records. Overall, our results indi8cate that numerous rapid changes in climate occurred in China during the last glacial cyfcle, but that the rage of climate variations was smaller than recorded in Greenland.

In this study, a 6m long core (16,000 BP) at the center of the dry Lake Yiema, a closed lake of Shiyang River drainage in Minqin Basin of the arid northwestern China, was retrieved to recover the history of climate changes and lake evolution in the area. Five radiocarbon dates on organic matter were obtained. A chronological sequence is established based on these five dates and other dates from nearby sites. Magnetic susceptibility, particle size and chemical composition were analysized for climate proxies. The proxies indicate that a drier climate prevailed in the Shiyang River drainage during the last glacial. Lake Yiema was dry and eolian sand covered most part of the lake basin. During the early and middle Holocene, a moister climate prevailed in the drainage. Climate became dry stepwise with an abrupt transition from one stage to another during the entire Holocene and became driest since about 4,200 BP. Maximum dry climate spells occurred at about 12,000-10,000 BP and after about 4,200 BP. A dry climate event also existed at about 7,600 BP. Periodical sand storms with about 400-yr cycle happened during the middle Holocene. Desiccation processes of the lake started at 4,200 BP, and were accelerated since the last 2,500 yrs by the inflow water diversion for agriculture irrigation. During the past 2,500 yrs, the lake size has been closed associated with the human population, implying that the human impact has been accelerating the lake desiccation superimposed on the natural climate deterioration.

Molecular stratigraphic analyses using GC/MS have been performed on the top section of the Jiuzhoutai loesspaleosol sequences near Lanzhou in northwest China, with a record extending from the second-last interglacial through the present interglacial. The various molecular fossils identified from the second-order loess and paleosol layers include C14-C35 n-alkanes, C8-C30 n-alkanoic acids, C12-C30 n-alkanols and C23-C33 n-alkan-2-ones. The CPI (carbon preference index) values and the ratio of C29/C31 n-alkan-2-ones display alternations between loess deposits and paleosols. They show a significant correlation with the loess magnetic susceptibility, an indicator of the East Asian summer monsoon. The observed variations of the ketone indices in relation to the change of lithology are proposed to result from microbial re-working of higher plant inputs in the paleosols.

Investigations of geomorphology and sedimentology, and analyses of radiocarbon dates, grain size and carbonate of the sediment at the present-dry closed basin in the terminal area of Shiyang River in arid China were conducted to recover the history of palaeolake change since the last glacial. The terminal area was covered by eolian sand before 13,000 14CBP. Lacustrine deposits covered the eolian sand after 13,000 14CBP, but were succeeded rapidly by eolian or fluvial deposits ca. 11,200-10,000 BP. This fact plus the grain-size distribution and CaCO3 content showed that climate was extremely dry during the last glacial, but wet-dry oscillations characterized the late glacial. A single coalescent lake, over 45m deep and 2130km2, formed between 10,000-6400 14C BP in the basin. The lake disintegrated into several shallow carbonate lakes or swamps gradually after 6400 14CBP. Eolian sand reached into the most part of the basin during the period. The lake evolution in the area generally reflects the East Asian summer monsoon history forced by Northern hemisphere insolation. Short time-scale lake fluctuations also existed in the area since the last glacial.