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Employing the Unit Soil Carbon Amount (USCA) approach, soil carbon storage was calculated across the Northeast Plain of China based on the Multi-purpose Regional Geochemical Survey conducted in 2004 – 2006 (MRGS). The results indicated that the soil organic carbon (SOC) storage in topsoil (0 – 0.2 m), subsoil (0 – 1 m) and deep soil (0 – 1.8 m) was 768.1 Mt, 2978.4 Mt and 3729.2 Mt with densities of 3327.8 t/km2, 12,904.7 t/km2 and 16,157.5 t/km2, respectively. These values were consistent with national averages, whereas the soil carbon densities showed a clear increasing trend from the southern area of the Northeast Plain (Liaoning), to the middle (Jilin) and the northern Plain (Heilongjiang) — particularly in terms of topsoil carbon density, which increased from 2284.2, to 3436.7 and 3861.5 t/km2, respectively. In comparison to carbon data obtained from the Second National Soil Survey in 1984 – 1986 (SNSS), the topsoil SOC storage values from the MRGS were found to have decreased by 320.59 Mt (29.4%), with an average annual decline of 16.0 Mt (l.73%) over the 20 years. In the southern, middle and northern areas of the plain, soil carbon densities decreased by 1060.6 t/km2, 1646.4 t/km2 and 1300.2 t/km2, respectively, with an average value of 1389.0 t/km2 for the whole plain. These findings indicate that the decrease in soil carbon density varied according to the different ecosystems and land use types. Therefore, ratios of soil carbon density were calculated in order to study the carbon dynamic balance between ecosystems, and to further explore distribution characteristics, as well as the sequestration potential of SOC. 相似文献
44.
Wei-min Ye Zi-yuan Qi Bao Chen Ji Xie Yu Huang Yao-ru Lu Yu-Jun Cui 《Environmental Earth Sciences》2011,64(1):269-276
Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement
rocks. It leads to drastic decrease in soil productivity and formation of a desert-like landscape. In this regard, changes
in climatic conditions are the main origin of the soils degradation. Indeed, soils subjected to successive dry/wet cycling
processes caused by climate change develop swelling and shrinkage deformations which can modify their water retention properties,
thus inducing the degradation of soil–water capacity. The ecological characteristics of cultivation soils in karst areas,
Southwest of China, are extremely easy to be affected by external environmental factors due to its shallow bedding and low
vegetation coverage. Based on the analysis of the climate (precipitation) of this region during the past decades, an experimental
study has been conducted on a cultivated soil obtained from the typical karst area in southwestern China. Firstly, the soil–water
properties have been investigated. The measured soil–water retention curve shows that the air-entry value of the soil is between
50 and 60 kPa, while the residual saturation is about 12%. Based on the experimental results, three identifiable stages of
de-saturation have been defined. Secondly, a special apparatus was developed to investigate the volume change behavior of
the soil with controlled suction cycles. The vapor equilibrium technique was used for the suction control. The obtained results
show that under the effect of dry/wet cycles, (1) the void ratio of the cultivated soil is continuously decreasing, leading
to a gradual soil compaction. (2) The permeability decreases, giving rise to a deterioration of water transfer ability as
well as a deterioration of soil–water retention capacity. It is then obvious that the long-term dry/wet cycling process caused
by the climate change induce a continuously compaction and degradation of the cultivated soil in karst rocky desertification
areas. 相似文献
45.
Contamination and distribution of heavy metals in urban and suburban soils in Zhangzhou City,Fujian, China 总被引:2,自引:0,他引:2
Zhen-ang Cui Sheng-ying Qiao Zheng-yu Bao Neng-you Wu 《Environmental Earth Sciences》2011,64(6):1607-1615
The urban environment is of growing concern as its continued population increase in China. Due to the urbanization and industrialization,
heavy metals have been continuously discharged into the soil recently, and creating the anthropogenic contamination. This
study investigated heavy metals contamination in urban and suburban soils in Zhangzhou City, Fujian, China. Multivariate analysis
and geographical information system technology were employed in source identification and contamination assessment of heavy
metals in the city soils. The survey results indicated that the urban soils were contaminated by heavy metals, especially
by Hg, Cd and Pb. The multivariate analysis demonstrated that the distribution of Cu, Zn, Cr and Ni was controlled by pedogenesis,
Cd and Pb had been disturbed by industrialization in some urban locations, and Hg was mainly influenced by the hot-spring
in some urban park sites. The distribution of heavy metals and soil pollution index suggested the soils of Zhangzhou City
have been affected by human activities. 相似文献
46.
The Thornthwaite Memorial, Synthetic, and Carnegie Ames Stanford Approach (CASA) models, with inputs from SPOT-VGT-S10 NDVI
data, meteorological data (precipitation, temperature, solar radiation), and land use data were used to estimate the values
of net primary productivity (NPP) from 1999 to 2007 in China’s Shiyanghe Basin. The human appropriation of NPP, which represents
the difference between potential NPP predicted using the climatic models and actual NPP calculated using the CASA model, served
as the indicator of human intervention in the evolution of productivity of the land. Analysis showed that 78.9% (~9,172 km2) of the degradation occurring in the Shiyanghe Basin was caused by human activities versus 15.0% (~1,752 km2) that was caused by climatic factors, whereas 16.9% (~6,404.5 km2) of the vegetation restoration resulted from human activities versus 49.7% (~18,881 km2) that resulted from climate changes. Human activity played a key role in vegetation restoration in the central areas of the
basin and in determining land degradation in the southwestern and northeastern areas. In addition, climate significantly controlled
the vegetation restoration in the southwestern and northeastern areas and controlled land degradation in the central area. 相似文献
47.
Assessing vegetation dynamics and their relationships with climatic variability in Heilongjiang province, northeast China 总被引:2,自引:1,他引:1
Wenbin Liu Tijiu Cai Cunyong Ju Guobin Fu Yuefeng Yao Xueqing Cui 《Environmental Earth Sciences》2011,64(8):2013-2024
In this study, the vegetation dynamics in Heilongjiang province and their relationships with climate variability were assessed
using normalized difference vegetation index (NDVI) and meteorological datasets from 1981 to 2003. The conclusions from our
results are as follows: (1) After 1981, vegetation cover, as indicated by the NDVI, exhibited an insignificant increasing
tendency. However, the inter-annual variations of the NDVI showed apparent spatial differentiations. (2) The inter-annual
changes of the NDVI were different from season to season. The spring and autumn NDVI values increased, while the summer and
winter NDVI decreased. (3) The annual NDVI was significantly correlated with precipitation. Thus, as compared to temperature,
precipitation was the dominant climatic factor affecting the vegetation dynamics in Heilongjiang province. (4) The trend in
the NDVI showed a marked homogeneity corresponding to regional and seasonal variations in climate. Additionally, land use
changes also play an important role in influencing the NDVI trends over some regions. All of these findings will enrich our
knowledge of the natural forces that impact the stability of boreal ecosystems and provide a scientific basis for the environmental
management in Heilongjiang province in response to climate change and human activities. 相似文献
48.
Researches on breaking-induced currents by waves are summarized firstly in this paper. Then, a combined numerical model in orthogonal curvilinear coordinates is presented to simulate wave-induced current in areas with curved boundary or irregular coastline. The proposed wave-induced current model includes a nearshore current module established through orthogonal curvilinear transformation form of shallow water equations and a wave module based on the curvilinear parabolic approximation wave equation. The wave module actually serves as the driving force to provide the current module with required radiation stresses. The Crank-Nicolson finite difference scheme and the alternating directions implicit method are used to solve the wave and current module, respectively. The established surf zone currents model is validated by two numerical experiments about longshore currents and rip currents in basins with rip channel and breakwater. The numerical results are compared with the measured data and published numerical results. 相似文献
49.
单核苷酸多态性(SNPs)是继RFLP和SSR多态性标记之后的新一代遗传标记系统.本文采用EPIC的方法,分析了45个杂色鲍样品的血蓝蛋白HtH1基因第16内含子(H1 intron 16)的SNP数据.这45个个体分别来自日本、台湾和汕头3个不同海域的野生或养殖群体.日本群体的血蓝蛋白HtH1基因第16内含子呈现出长度多态性,共有3种不同长度,分别是1 900、780、440 bp,测序结果表明3个等位基因可以互相比对;而台湾和汕头杂色鲍养殖群体的均为1 900 bp.初步研究结果表明日本杂色鲍个体大约96 bp长的片段含有1个自身杂合SNP位点;台湾杂色鲍个体约133 bp含有1个自身杂合SNP位点;汕头杂色鲍个体约153 bp含有1个自身杂合SNP位点.13个台湾杂色鲍个体包含的SNP密度为约31 bp含有1个SNP;23个汕头杂色鲍个体包含的SNP密度为约21 bp含有1个SNP.这些数据表明现有的杂色鲍养殖群体包含了丰富的SNP位点,利用SNP分子标记进行高密度遗传图谱的构建是可行的. 相似文献
50.
Previously, we had characterized several structurally interesting brominated phenols from the marine red alga Symphyocladia latiuscula collected from various sites. However, Phytochemical investigations on this species collected from the Weihai coastline of Shandong Province remains blank. Therefore, we characterized the chemical constituents of individuals of this species collected from the region. Eight bromophenols were isolated and identified. Using detailed spectroscopic techniques and comparisons with published data, these compounds were identified as 2,3-dibromo-4,5-dihydroxybenzyl methyl ether (1), 3,5-dibromo-4-hydroxybenzoic acid (2), 2,3,6-tribromo-4,5-dihydroxymethylbenzene (3), 2,3,6-tribromo-4,5-dihydroxybenzaldehyde (4), 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (5), bis(2,3,6-tribromo-4,5-dihydroxyphenyl)methane (6), 1,2-bis(2,3,6-tribromo-4,5-dihydroxyphenyl)-ethane (7), and 1-(2,3,6-tribromo-4,5-dihydroxybenzyl)-pyrrolidin-2-one (8). Among these compounds, 1 and 2 were isolated for the first time from S. latiuscula. Each compound was evaluated on the ability to inhibit protein tyrosine phosphatase 1B (PTP1B), which is a potential therapeutic target in the treatment of type 2 diabetes. Bromophenols 5, 6, and 7 showed strong activities with IC50 values of 3.9, 4.3, and 3.5 μmol/L, respectively. This study provides further evidence that bromophenols are predominant among the chemical constituents of Symphyocladia, and that some of these compounds may be candidates for the development of anti-diabetes drugs. 相似文献