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Global warming mainly due to emissions of carbon dioxide (CO2) and other greenhouse gases has initiated wide interest in the investigation of various land CO2 sequestration mechanisms. As a long-term terrestrial carbon sequestration mechanism, phytolith carbon sequestration may play an important role in the global carbon cycle and climate change. This study investigated the distribution of phytoliths and phytolith-occluded carbon (PhytOC) in shrublands of North China to understand the potential of phytolith carbon sequestration within shrublands. The results indicated positive correlations between PhytOC content of biomass and phytolith content of biomass in the shrub layer, and between PhytOC content of biomass and carbon content of phytoliths in the herb layer of shrublands. The PhytOC production fluxes of five shrublands through shrub leaves and herb layers were 4.12-7.94 kg CO2 ha-1 a-1 with an average of 5.95 kg CO2 ha-1 a-1, and decreased in the following order: Ostryopsis davidianashrubland > Spiraea salicifolia-shrubland ≈ Armeniaca sibirica-shrubland > Ziziphus jujuba-shrubland > Vitex negundo-shrubland. The mean rate of PhytOC production in temperate shrubland of North China was 0.45 ± 0.09 Tg CO2 a-1. The data indicate that phytolith carbon sequestration in shrublands is a significant mechanism to mediate the increase of atmospheric CO2. The potential of phytolith carbon sequestration in China's shrublands may be further enhanced by adaptive management of shrublands, such as conservation of plant species with high PhytOC production flux. [ABSTRACT FROM AUTHOR]

Phytolith-occluded carbon (PhytOC) is a stable carbon (C) fraction that has effects on long-term global C balance. Here, we report the phytolith and PhytOC accumulation in moso bamboo leaves developed on four types of parent materials. The results show that PhytOC content of moso bamboo varies with parent material in the order of granodiorite (2.0 g kg-1)> granite (1.6 g kg-1)> basalt (1.3 g kg-1) . shale (0.7 g kg-1). PhytOC production flux of moso bamboo on four types of parent materials varies significantly from 1.0 to 64.8 kg CO2 ha-1 yr-1, thus a net 4.7 × 106 -310.8 × 106 kg CO2 yr-1 would be sequestered by moso bamboo phytoliths in China. The phytolith C sequestration rate in moso bamboo of China will continue to increase in the following decades due to nationwide bamboo afforestation/reforestation, demonstrating the potential of bamboo in regulating terrestrial C balance. Management practices such as afforestation of bamboo in granodiorite area and granodiorite powder amendment may further enhance phytolith C sequestration through bamboo plants. [ABSTRACT FROM AUTHOR]

Phytoliths, the amorphous silica deposited in plant tissues, can occlude organic carbon (phytolith-occluded carbon, PhytOC) during their formation and play a significant role in the global carbon balance. This study explored phylogenetic variation of phytolith carbon sequestration in bamboos. The phytolith content in bamboo varied substantially from 4.28% to 16.42%, with the highest content in Sasa and the lowest in Chimonobambusa, Indocalamus and Acidosasa. The mean PhytOC production flux and rate in China's bamboo forests were 62.83 kg CO2 ha-1 y-1 and 4.5 x 108 kg CO2 y-1, respectively. This implies that 1.4 x 109 kg CO2 would be sequestered in world's bamboo phytoliths because the global bamboo distribution area is about three to four times higher than China's bamboo. Therefore, both increasing the bamboo area and selecting high phytolith-content bamboo species would increase the sequestration of atmospheric CO2 within bamboo phytoliths. [ABSTRACT FROM AUTHOR]

CO consumption by silicate weathering has exerted a major control on atmospheric CO over geologic time. In order to assess plant impact on this process, the study compared water geochemistry and CO consumption rates by silicate weathering in watersheds covered by bamboos and other forests. Our study showed that SiO concentrations (80 ~ 150 μmol/L, average 105 μmol/L) in water from pure bamboo forest watersheds were higher than that (15 ~ 85 μmol/L, average 60 μmol/L) from other watersheds. Si/(Na + K) ratios in water draining from bamboo watersheds (2.0 ~ 4.0, average 2.9) were higher than that from other watersheds ?>(0.7 ~ 2.7, average 2.2). CO consumption rates by silicate weathering in bamboo watersheds (1.8 ~ 3.4 10 mol/km/yr, average 2.5 10 mol/km/yr) were higher than that in other watersheds (1.5 ~ 2.6 10 mol/km/yr, average 2.0 10 mol/km/yr). Therefore, bamboo-enhanced silicate weathering is a potential biogeochemical remediation approach for atmospheric CO. [ABSTRACT FROM AUTHOR]

Weathering of heavy metal enriched black shales may be one of the most important sources of environmental contamination in areas where black shales are distributed. Heavy metal release during weathering of the Lower Cambrian Black Shales (LCBS) in western Hunan, China, was investigated using traditional geochemical methods and the ICP-MS analytical technique. Concentrations of 16 heavy metals, 8 trace elements and P were measured for samples from selected weathering profiles at the Taiping vanadium ore mine (TP), the Matian phosphorous ore mine (MT), and Taojiang stone-coal mine (TJ). The results show that the bedrock at these three profiles is enriched with Sc, V, Cr, Co, Ni, Cu, Zn, Pb, Th, U, Mo, Cd, Sb, Tl, and P. Based on mass-balance calculation, the percentages of heavy metals released (in % loss) relative to immobile element Nb were estimated. The results show significant rates of release during weathering of: V, Cr, Co, Ni, Cu, Zn, U, Mo, Cd, Sn, Sb, and Tl for the TP profile; Sc, Cr, Mn, Co, Ni, Cu, Zn, Pb, Th, Cd, and Sn for the MT profile; and Sc, Mn, Co, Ni, Zn, Th, Cd, Sn, and Tl for the TJ profile. Among these heavy metals, Co, Ni, Zn, Cd, and Sn show very similar features of release from each of the three weathering profiles. The heavy metals released during weathering may affect the environment (especially topsoil and surface waters) and are possibly related to an observed high incidence of endemic diseases in the area. [ABSTRACT FROM AUTHOR]