Effects of afforestation on soil carbon turnover in China's subtropical region

Afforestation in China's subtropics plays an important role in sequestering CO2 from the atmosphere and in storage of soil carbon (C). Compared with natural forests, plantation forests have lower soil organic carbon (SOC) content and great potential to store more C. To better evaluate the effects of afforestation on soil C turnover, we investigated SOC and its stable C isotope (delta C-13) composition in three planted forests at Qianyanzhou Ecological Experimental Station in southern China. Litter and soil samples were collected and analyzed for total organic C, delta C-13 and total nitrogen. Similarly to the vertical distribution of SOC in natural forests, SOC concentrations decrease exponentially with depth. The land cover type (grassland) before plantation had a significant influence on the vertical distribution of SOC. The SOC delta C-13 composition of the upper soil layer of two plantation forests has been mainly affected by the grass biomass C-13 composition. Soil profiles with a change in photosynthetic pathway had a more complex C-13 isotope composition distribution. During the 20 years after plantation establishment, the soil organic matter sources influenced both the delta C-13 distribution with depth, and C replacement. The upper soil layer SOC turnover in masson pine (a mean 34% of replacement in the 10 cm after 20 years) was more than twice as fast as that of slash pine (16% of replacement) under subtropical conditions. The results demonstrate that masson pine and slash pine plantations cannot rapidly sequester SOC into long-term storage pools in subtropical China.

ROLE OF PHOSPHORUS CYCLING IN ALGAL METABOLISM AND ALGAL SUCCESSION IN LAKE DONGHU, CHINA

The role of phosphorus cycling in algal metabolism was studied in a shallow lake, Donghu, in Wuhan using the methods of measuring cell quota C, N and P, and calculating nutrients uptake rate by algal photosynthesis. The mean daily phosphorus uptake rate of phytoplankton varied between 0.04-0.11 and 0.027-0.053 g/m2/d in station I and station II respectively. The turnover time of phosphorus in phytoplankton metabolism ranged from 0.75-5.0 days during 1979-1986. The available P was 0.176 (+/- 0.156) g/m3 (mean +/- SD) in 1982 and 0.591 (+/- 0.24) g/m3 in 1986. The relationship between P/B ratio (Y) and TP (X: mg/l) was described by the following regression equation Y = 1.163 + 0.512logX (r = 0.731, P < 0.001). The dynamics of algal biomass and algal species succession were monitored as the indicators of environmental enrichment. The small-sized algae have replaced the blue-green algae as the dominant species during 1979-1986. The small-sized algae include Merismopedia glauca, Cryptomonas ovata, Cryptomonas erosa, several species Cyclotella. There has been drastic decrease in algal biomass and an obvious increase in P/B ratio. A nutrient competition hypothesis is proposed to explain the reason of the disappearance of blue-green algae bloom. The drastic change in algal size and the results in high P/B ratio (reaching a maximum mean daily ratio of 1.09 in 1986) may suggest a transition of algal species from K-selection to r-selection in Lake Donghu.

The Impact of Environmental Non-Tariff Measures on China's Agricultural Exports

This article assesses the impact of environmental non-tariff measures on China's agricultural exports. It uses two measures to show which countries make most intensive use of environmental non-tariff measures and which agricultural products exported by China are the most affected. Environmental non-tariff measures were most prevalence in Malaysia, Vietnam, Philippines, Mexico, Japan, Russian, USA, Germany, and Netherland. Labor-intensive agricultural products, such as fish, vegetables, and fruit were most seriously affected.

Spatial variability in biomass and production of heterotrophic bacteria in the East China Sea and the Yellow Sea

The distributions of heterotrophic bacterial abundance and production were investigated in the East China Sea and the Yellow Sea during the autumn of 2000 and spring of 2001. Bacterial abundance varied in the range 3.2-15.7 (averaging 5.7) x 10(5) and 2.3-13.6 (averaging 6.2) x 10(5) cells cm(-3) in the spring and autumn, respectively. During autumn, bacterial production (BP) (0.27-7.77 mg C m(-3) day(-1)) was on average 3 fold that in spring (0.001-2.04 mg C m(-3) day(-1)). Bacterial average turnover rate (ratio of bacterial production:bacterial biomass, mu=0.21 day(-1)) in autumn was 3 times as high as in spring (0.07 day(-1)). The ratio of integrated bacterial biomass to integrated phytoplankton biomass in the euphotic zone ranged from 4 to 101% (averaging 35%) in spring and 24 to 556% (averaging 121%) in autumn. The results indicate that the distributions of heterotrophic bacteria were controlled generally by temperature in spring and additionally by substrate supply in autumn. (C) 2010 Elsevier Ltd. All rights reserved.

Environmental Mechanics Research in China

By recalling mankind's path during past 50 years in the present article, we mainly highlight the significance of environmental issues today. In particular, two major factors leading to environment deterioration in China such as water resources and coal burning are stressed on. Present-day environmental issues are obviously interdisciplinary, of multiple scales and multi-composition in nature. Therefore, a process-based approach for environment research is absolutely necessarily. A series of sub-processes, either physical, chemical or biological, are subsequently analyzed in order to established reasonable parameterization scheme and credible comprehensive model. And we are now in a position to answer questions still open to us, improve existing somewhat empirical engineering approaches and enhance quantitative accuracy in prediction. To illustrate this process-based research approach, three typical examples associated with the Yangtze River Estuary, Loess Plateau and Tenggeli Desert environments have been dealt with respectively. A theoretical model of vertical flow field accounting for runoff and tide interaction has been established to delineate salinity and sediment motion which are responsible for the formation of mouth bar at the outlet and the ecological evolution there. A kinematic wave theory combined with the revised Green-Ampt infiltration formula is applied to the prediction of runoff generation and erosion in three types of erosion region on the Loess Plateau. Three approaches describing water motion in SPAC system in arid areas at different levels have been improved by introducing vegetation sub-models. However, we have found that the formation of a dry sandy layer and biological crust skin are additional primary causes leading to deterioration of water supply and succession of ecological system.

Some Key Technics of Drop Tower Experiment Device of National Microgravity Laboratory (China) (NMLC)

Drop tower is an important ground based facility for microgravity science experiment. The technical performances of the drop tower NMLC are advanced compared with similar facilities in the US, Germany and Japan. The main components such as drop capsule, deceleration devices, release mechanism present its advantages and creativities.

Study on Microstructure and Nanomechanics Properties of Antibacterial Bone China

Fracture appearance, surface and nanomechanics properties of antibacterial ceramics contairing rare earth phosphate composite antibacterial materials were characterized and measured by SEM, AFM and Nanoindenter, respectively. Results show that grain of fracture surface of antibacterial ceramics grows uniform refinement topography of bubble break-up appears at the surface, which is flat and has liquid character, by adding the phosphate composite containing rare earth, nevertheless needle-like crystal and granular outgrowth form at fracture surface and surface of common ceramics, respectively. Young's modulus of antibacterial ceramic film is 74. 397 GPa and hardness is 8. 134 GPa, which increses by 4.4﹪ and 1.6﹪ comparing with common ceramics, respectively. Loading curves of two kind of ceramics have obvious nonlinear character under 700 nm and linear character between 700 ～ 1000 nm, and unloading curve have obvious linear character.

Main Progress of Microgravity Sciences and Space Life Sciences Research in China

The progress of the research activities on space material sciences, microgravity ‰uid physics and combustion, space life sciences and biotechnology research, fundamental Physics in China are brie‰y summarized in the present paper. The major space missions and experimental results obtained on board the Chinese recoverable/non-recoverable satellites and the Chinese manned spaceship named ``Shen-Zhou'' are presented summarily. The recent main activities of the ground-based studies in China are introduced in brief.