**5. Acknowledgement**

146 International Perspectives on Global Environmental Change

The variations of Ti and Br contents in core HDP-06 are similar to that of PME over the Holocene period (Figs. 6a, b, and f). The relationship between Ti and PME shows an inverse correlation, whereas the relationship between Br and PME shows a positive correlation. In the mid-Holocene, the Ti intensity peaks at low PME, and the Br content increases in the early- and late-Holocene when the PME rises. On the other hand, the PC-2 score in core X106 (Fig. 6d), together with annual mean temperature in central Asia (Fig. 6e) and atmospheric CO2 concentration (Fig. 6f), shows a gradual increase from about 8.0 ka to the

These two-type variations observed in cores HDP-06 and X106 are considered to have resulted from changes in erosion/weathering intensity of central Asia (Asian continental

Evidences and suggestions supporting our hypothesis are provided by studies on the sediment from Lake Hovsgol. Prokopenko et al. (2007) showed that the early Holocene diatom/biogenic silica (bioSi) peaks correlated with the humidity maximum (Fig. 6f) reconstructed by the pollen fossil analyses and from predictions of GCMs (Bush, 2005). Based on these observations, Prokopenko et al. (2007) regarded that the early Holocene increase of diatom abundance in Lake Hovsgol was caused by increased nutrient supply with high precipitation and surface runoff. The early Holocene diatom/bioSi peaks correspond to the increased Br contents in core HDP-06 (Fig. 6a). Murakami et al. (2010) observed that low PC-2 detrital input occurred during the early Holocene (Fig. 4d). To explain the early Holocene decease of erosion/weathering intensity in the drainage basin with high humidity, Murakami et al. (2010) proposed that the detritus supply to Lake Hovsgol may have been controlled by the amount of vegetation cover: (1) vegetation cover in the catchment increased with high precipitation; (2) as a result, the nutrient supply to the lake enhanced, which in turn resulted in high productivity in the lake; (3) simultaneously, declined erosion through the drainage basin resulted in a reduced sediment supply into the

The interpretation for the early Holocene detritus input by Murakami et al. (2010) can apply to the gradual increase from about 8.0 ka observed in the PC-2 score (Fig. 6d), the regional annual mean temperature (Fig. 6e), and atmospheric CO2 concentration (Fig. 6g): (1) the annual mean temperature increases with the rise in atmospheric CO2; (2) because of the exponential increase of the saturation vapor pressure with air temperature, the moisture decreases; (3) the resultant aridity of the continental interior has intensified the

We measured nondestructively 11 major and traces elements in the Holocene sediment of core HDP-06 core from Lake Hovsgol, using SR μ-XRF mapping techniques. A visual inspection of the acquired XRF images revealed that the 11 elements were classified into the three assemblages–group 1: Ti, Fe, Cu, Zn, As, Rb, Sr, Zr, and Nb, composed of rockforming minerals; group 2: Br, recognized as a biophilic trace elements; and group 3: Mn, Fe,

Temporal variations in the first two groups, based on the age of core X106, are in phase with GCM-simulated PME in central Asia. This trend is remarkably different from the PC-2 score of core X106 indicating detritus input into the lake. The PC-2 score, together with atmospheric CO2 and the regional annual mean temperature, shows a gradual increase from

present day.

lake.

interior) with moisture changes.

erosion/weathering processes.

and As, sensitive to redox condition in the sediment.

**4. Conclusions** 

The authors are very grateful to the staff of Technical Center of Nagoya University. K. Suzuki provided helpful support in designing a sheet bender. S. Yogo made many helpful suggestions on sample preparation. A part of μ-XRF analysis was performed with the approval of SPring-8 (Proposal No. 2006B1091 and 2007A1563). We also thank to Y. Terada for μ-XRF mappings using synchrotron radiation. We are grateful to the HDP members for subsampling from the HDP-06 core. This study was supported by the Sumitomo Foundation grant No.103359; the Saijiro Endo Memorial Foundation; awards from Dynamics of the Sun-Earth-Life Interactive System, No. G-4 at Nagoya Univ., and Environmental Monitoring and Prediction of Long- and Short-Term Dynamics of Pan-Japan Sea Area, No. E-07 at Kanazawa Univ., of the 21st Century COE Program of the Ministry of Education, Culture, Sports, Science and Technology, Japan.
