Two atmospheric circulation systems, the mid-latitude Westerlies and the Asian summer monsoon (ASM), play key roles in northern-hemisphere climatic changes. However, the variability of the Westerlies in Asia and their relationship to the ASM remain unclear. Here, we present the longest and highest-resolution drill core from Lake Qinghai on the northeastern Tibetan Plateau (TP), which uniquely records the variability of both the Westerlies and the ASM since 32 ka, reflecting the interplay of these two systems. These records document the anti-phase relationship of the Westerlies and the ASM for both glacial-interglacial and glacial millennial timescales. During the last glaciation, the influence of the Westerlies dominated; prominent dust-rich intervals, correlated with Heinrich events, reflect intensified Westerlies linked to northern high-latitude climate. During the Holocene, the dominant ASM circulation, punctuated by weak events, indicates linkages of the ASM to orbital forcing, North Atlantic abrupt events, and perhaps solar activity changes.

Summary Learning-related plasticity at excitatory synapses in the mammalian brain requires the trafficking of AMPA receptors and the growth of dendritic spines. However, the mechanisms that couple plasticity stimuli to the trafficking of postsynaptic cargo are poorly understood. Here we demonstrate that myosin Vb (MyoVb), a Ca2+-sensitive motor, conducts spine trafficking during long-term potentiation (LTP) of synaptic strength. Upon activation of NMDA receptors and corresponding Ca2+ influx, MyoVb associates with recycling endosomes (REs), triggering rapid spine recruitment of endosomes and local exocytosis in spines. Disruption of MyoVb or its interaction with the RE adaptor Rab11-FIP2 abolishes LTP-induced exocytosis from REs and prevents both AMPA receptor insertion and spine growth. Furthermore, induction of tight binding of MyoVb to actin using an acute chemical genetic strategy eradicates LTP in hippocampal slices. Thus, Ca2+-activated MyoVb captures and mobilizes of REs for AMPA receptor insertion and spine growth, providing a mechanistic link between the induction and expression of postsynaptic plasticity.

There is a growing public concern over the potential accumulation of heavy metals in agricultural soils in China owing to rapid urban and industrial development and increasing reliance on agrochemicals in the last several decades. Excessive accumulation of heavy metals in agricultural soils may not only result in environmental contamination, but elevated heavy metal uptake by crops may also affect food quality and safety. The present study is aimed at studying heavy metal concentrations of crop, paddy and natural soils in the Pearl River Delta, one of the most developed regions in China. In addition, some selected soil samples were analyzed for chemical partitioning of Co, Cu, Pb and Zn.The Pb isotopic composition of the extracted solutions was also determined. The analytical results indicated that the crop, paddy and natural soils in many sampling sites were enriched with Cd and Pb. Furthermore, heavy metal enrichment was most significant in the crop soils, which might be attributed to the use of agrochemicals.

"Capsule": Urban environmental geochemistry as a scientific discipline provides valuable information on trace metal contamination of the urban environment and its associated health effects. AbstractAs the world's urban population continues to grow, it becomes increasingly imperative to understand the dynamic interactions between human activities and the urban environment. The development of urban environmental geochemistry has yielded a significant volume of scientific information about geochemical phenomena found uniquely in the urban environment, such as the distribution, dispersion, and geochemical characteristics of some toxic and potentially toxic trace metals. The aim of this paper is to provide an overview of the development of urban environmental geochemistry as a field of scientific study and highlight major transitions during the course of its development from its establishment to the major scientific interests in the field today. An extensive literature review is also conducted of trace metal contamination of the urban terrestrial environment, in particular of urban soils, in which the uniqueness of the urban environment and its influences  Corresponding author (X. D. Li): E-mail address: cexdli@polyu.edu.hk. Tel.: +852-2766-6041; Fax: +852-2334-6389. This is the Pre-Published Version.2 on trace metal contamination are elaborated. Last, potential areas of future development in urban environmental geochemistry are identified and discussed.

Photodecomposition of hydrogen peroxide on TiO2 surfaces under visible irradiation (λ > 420 nm) was investigated, and an interesting result was found that small organic compounds such as salicylic acid were degraded in the presence of TiO2 and H2O2 under visible irradiation, although either TiO2 or H2O2 alone cannot absorb visible light to decompose H2O2 or small organic compounds. Furthermore, the effects of H2O2 concentration, pH, and the wavelength of irradiation light on the degradation of H2O2 were studied. The photodegradation of H2O2 occurred via a zero-order process, and •OH radicals were detected by electron paramagnetic resonance experiments in visible-light-irradiated aqueous TiO2 suspensions. A reaction mechanism for the decomposition of H2O2 on the TiO2 surfaces is proposed involving a photoinduced electron transfer of the surface complexes of ⋮TiIV−OOH.

The effect of metal ions (Cu 2+ , Fe 3+ , Zn 2+ , Al 3+ , and Cd 2+ ) on the photodegradation of several dyes: sulforhodamine B (SRB), alizarin red (AR), and malachite green (MG) has been investigated in aqueous TiO 2 dispersions under visible irradiation (λ > 420 nm). Trace quantities of transition metal ions such as Cu 2+ and Fe 3+ having suitable redox potentials alter the electron-transfer pathway involving the dye, O 2 and TiO 2 particles, and markedly depress the photodegradation of all three dyes under visible irradiation. Other metal ions, such as Zn 2+ , Cd 2+ , and Al 3+ , have only a slight influence on the photoreaction by altering the adsorption of dyes. Photogeneration of H 2 O 2 and reactive radicals, and the changes in fluorescence emission of SRB in TiO 2 aqueous dispersions were examined to elucidate the role of the metal ions. Addition of Cu 2+ or Fe 3+ decreases the reduction of O 2 by the conduction electrons, subsequently blocks the formation of reactive oxygen species (O -• , • OH), and depresses the degradation of dyes under visible irradiation. We deduce that the reduction of O 2 is essential for the photodegradation of dyes under visible irradiation.

The contamination of urban soils can affect the health of people living in urban areas, and the surrounding ecosystems. Urbanization in China has taken place at an unprecedented pace in the last three decades. This paper provides an overview of studies on the quality of urban soils in China with special reference to trace metal contamination. It summarizes the characteristics of accumulation, spatial and temporal distribution, and major sources of various toxic or potentially toxic trace metals in urban soils as reported in recent literature. Levels of pollution in urban soil and road dust were discussed using the concentrations, enrichment factors, pollution indexes, and chemical fractionation of trace metals in major cities of China, and compared with other countries. In future studies, more pollutants in urban environments need to be included in multi-compartmental environmental surveillance for potential risk assessments. In addition to routine urban soil surveys by a harmonized methodology, a comprehensive assessment of soil quality is needed for the control and management of many urban brownfield sites. Taking into consideration pathways of exposure and site characteristics, risk assessment frameworks for major pollutants in urban soils, which integrate land use type and environmental availability, may be developed in the future.

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