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Geochemical dynamics of cave water were monitored to unveil its seasonal variation and controlling factors from December 2011 to May 2013 in Baojinggong cave, north of Guangdong Province. Concentrations of elements such as Ba, Sr, Ca and Mg of three drips in the cave were analyzed. The results showed that: (1) All these elements of three drips displayed significant seasonal variations, but the trends of seasonal variation of different elements or different drips were not the same, which reflected that each element in different drips might be controlled by different effects; (2) The low element contents of Drip1 and Drip2 during the heavy rainfall month showed that heavy rainfall could dilute the concentrations of elements; (3) Mg/Ca had a positive relationship with Sr/Ca ratio in three drips, and was higher in dry season and lower in rainy season. It implied that the two proxies might be mainly controlled by precipitation, karst water source, leaching effect and prior calcite precipitation (PCP), and reflected the climate change.

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The Homo erectus cranium from Gongwangling, Lantian County, Shaanxi Province is the oldest fossil hominin specimen from North China. It was found in 1964 in a layer below the Jaramillo subchron and was attributed to loess (L) L15 in the Chinese loess-palaeosol sequence, with an estimated age of ca. 1.15 Ma (millions of years ago). Here, we demonstrate that there is a stratigraphical hiatus in the Gongwangling section immediately below loess 15, and the cranium in fact lies in palaeosol (S) S22 or S23, the age of which is ca. 1.54-1.65 Ma. Closely spaced palaeomagnetic sampling at two sections at Gongwangling and one at Jiacun, 10 km to the north, indicate that the fossil layer at Gongwangling and a similar fossil horizon at Jiacun were deposited shortly before a short period of normal polarity above the Olduvai subchron. This is attributed to the Gilsa Event that has been dated elsewhere to ca. 1.62 Ma. Our investigations thus demonstrate that the Gongwangling cranium is slightly older than ca. 1.62 Ma, probably ca. 1.63 Ma, and significantly older than previously supposed. This re-dating now makes Gongwangling the second oldest site outside Africa (after Dmanisi) with cranial remains, and causes substantial re-adjustment in the early fossil hominin record in Eurasia.

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Monthly atmospheric deposition was collected in Northeast of Sichuan Province from August 2011 to July 2012. Contents of Na, Mg, Ca, K, Si, Sr, Ba and Zn in weak-acid leachable fraction (with pH values of ca. 2) of the deposition were determined using ICP-MS. The results indicated that the deposition fluxes of all these elements exhibited notable seasonal variations. For example, the deposition flux of Na increased with precipitation, suggesting a dominant derivation from wet deposition; whereas the fluxes of Ca, Ba, Si, Sr and Mg displayed higher values during winter or spring season, suggesting that these elements may be closely associated with atmospheric dust activity. The annual fluxes of these elements were remarkably different in value. Na had the highest flux of 30 497 microg x (10(2) cm2 x a)(-1), more than three orders of magnitude higher than the lowest flux of Ba of 27.4 microg x (10(2) cm2 x a)(-1).

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In a pilot study, arsenic in a stalagmite (SJ3) collected from Central China was measured, and its association with past climate and environment was explored. Most of the SJ3 arsenic concentrations ranged from 120 to 320 ppb with the highest concentrations associated with relatively warm and humid climatic phases and lowest concentrations with cold and dry phases. The SJ3 arsenic record was very similar to the manganese record of SJ3. Variations of arsenic in SJ3 might be controlled by metal oxides of iron, manganese, and aluminum in karst groundwater at the study site, which in turn were closely related with changes in past climate and environment. A considerable proportion of arsenic was in excess over manganese in SJ3, which might be related with incorporation of arsenic into the calcite lattice during the formation of SJ3. It was speculated that more arsenic was released due to stronger weathering of the surface soils and sequestrated by metal oxides in karst groundwater under warm-humid climatic phases than under cold-dry phases. This suggested that climate shift might alter arsenic balance in sedimentary areas and aquifer systems and potentially exert significant influence on global arsenic contamination.

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The Asian summer monsoon has been precisely reconstructed from the high-resolution record from the speleothem, but reconstruction of the Asian winter monsoon is less satisfactory. Yancheva et al. provide such a reconstruction for the last 16,000 years from the titanium (Ti) content of the sediments of Lake Huguang Maar in coastal South China. However, we argue that the Ti is likely to have come mainly from the catchment and so the Ti content may instead be related to the hydrology of the lake.

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The Pearl River Delta Economic Zone is the most dynamic economic area in South China. One of the major problems in the region is the sustainable utilization of the water resources. On the basis of analysis of the water environment status and pollution sources, it is suggested that domestic sewage is the primary cause of pollution. Two new concepts "degradation coefficient" and "degradation volume" of water resources, due to pollution, which may be used to assess macroscopically the carrying capacity of the water resources and sustainability of the water environment, are proposed by the authors. The results calculated indicate that the volumes of degraded water resources will be up to 204, 352, and 537 million m3 in 2002, 2010, and 2020. It is suggested that water for daily consumption and domestic sewage must be controlled more effectively and there should be cross-regional coordination in tackling problems of water environment.

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