Optimization of the time series NDVI-rainfall relationship using linear mixed-effects modeling for the anti-desertification area in the Beijing and Tianjin sandstorm source region

Theoretical and Applied Climatology - Degradation in drylands is a critically important global issue that threatens ecosystem and environmental in many ways. Researchers have tried to use remote...     

Assessing the effects of oyster/kelp weight ratio on water column properties: an experimental IMTA study at Sanggou Bay,China

Journal of Oceanology and Limnology - Integrated Multi-Trophic Aquaculture (IMTA) is an effective method for sustainable aquaculture as species from different trophic levels could reduce negative...     

Methane seepage in the Shenhu area of the northern South China Sea: constraints from carbonate chimneys

Two authigenic carbonate chimneys were recovered from the Shenhu area in the northern South China Sea at approximately 400 m water depth. The chimneys’ mineralogy, isotopic composition, and lipid biomarkers were studied to examine the biogeochemical process that induced the formation of the chimneys. The two chimneys are composed mostly of dolomite, whereas the internal conduits and semi-consolidated surrounding sediments are dominated by aragonite and calcite. The specific biomarker patterns (distribution of lipids and their depleted δ¹³C values) indicate the low occurrence of methanotrophic archaea ANME-1 responsible for the chimneys’ formation via anaerobic oxidation of methane. A significant input of bacteria/planktonic algae and cyanobacteria to the carbon pool during the precipitation of the carbonate chimneys is suggested by the high contributions of short-chain n-alkanes (69% of total hydrocarbons) and long-chain n-alcohols (on average 56% of total alcohols). The oxygen isotopic compositions of the carbonate mixtures vary from 3.1‰ to 4.4‰ in the dolomite-rich chimneys, and from 2.1‰ to 2.5‰ in the internal conduits, which indicates that they were precipitated from seawater-derived pore waters during a long period covering the last glacial and interglacial cycles. In addition, the mixture of methane and bottom seawater dissolved inorganic carbon could be the carbon sources of the carbonate chimneys.     

Characteristics of the surface mixed layer depths in the northern South China Sea in spring

The nature and characteristics of the mixed layer depth (MLD) remain uncertain in the northern South China Sea. Using in situ data, we examined the quality of different MLD definitions, investigated the spatial and diurnal variation in the MLD, and examined the mechanisms of mixed layer development during March 23–31, 2014. We made distinct calculations of the MLD; of which two are (a) the depths between two different temperatures (0.2, 0.6 °C) and (b) the depths between two density differences (0.125, 0.25 kg/m³); and the fifth calculation is a depth derived from the optimal linear fitness method. We found that the optimal linear fitness MLD was the best definition for our study region ,and that it deepened from the shelf to the slope. Twenty-four-hour diurnal variation in the MLDs and mixing layers was observed when the ship was moored. Mixing layers were characterized by turbulent dissipation rates. We found that the mixed layer underwent a ‘stable-decaying–developing’ process. During the stable period, the MLD was close to that of the mixing layer, but during the decay/development periods, the MLDs were larger/smaller than those of the mixing layers. We suggest that both velocity shear and buoyancy flux were important in mixed layer development. We quantitatively examined the mechanisms of mixing in the shelf region, with air–sea net heat flux determined to be the major factor, rather than wind speed or current velocity.     

Bioactive compounds of sea cucumbers and their therapeutic effects

Sea cucumbers belong to the Class Holothuroidea of marine invertebrates. They are commercially valuable and prized as a food and folk medicine in Asia. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as vitamins, minerals and amino acids. A number of unique biological and pharmacological activities/properties, including anticancer, anticoagulant/antithrombotic, antimicrobial, antioxidant, antihyperlipidemic, antihyperglycemic, anti-inflammatory, antihypertension and radioprotective, have been ascribed to various compounds isolated from sea cucumbers. The therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives, especially triterpene glycosides, acid mucopolysaccharide, sphingoid bases, glycolipids, fucosylated chondroitin sulfate, polysaccharides, phospholipids, cerebrosides, phosphatidylcholines, and other extracts and hydrolysates. This review highlights the valuable bioactive components as well as the multiple therapeutic properties of sea cucumbers with a view to exploring their potential uses as functional foods and a natural source of new multifunctional drugs.     

Temporal and spatial patterns of Cenozoic deformation across the Qaidam Basin,Northern Tibetan Plateau

We conducted a systematic analysis of the temporal and spatial patterns of Cenozoic deformation of the northeastern (NE) and southwestern (SW) parts of the Qaidam Basin, the largest and thickest Cenozoic sedimentary basin within the Tibetan Plateau, by constructing balanced cross‐sections traversing the whole basin using high‐resolution seismic‐reflection data. We found that that these two parts deformed synchronously with similar temporal patterns involving nearly constant NE–SW contraction before c. 2.5 Ma and much more intense shortening, possibly enhanced by fierce wind erosion, since then. However, the spatial deformation patterns of these two areas differ markedly: an eastward weakening trend in the SW part is not observed in the NE part. We believe that this difference is due to their different boundary conditions. This result places new constraints on the formation mechanisms of the northern Tibetan Plateau.     

泾河中游地区全新世成壤环境演变研究

根据长武ETC全新世土壤剖面的测定分析,探讨了该地区全新世成壤环境演变过程,阐明了先周时代土壤特征及人类耕作对成壤过程的影响。研究结果表明,全新世早期气候温和干燥,沙尘暴明显减弱,风尘堆积速率降低,具有轻微生物风化成壤作用;对应于全新世最适宜期,该地气候温暖湿润,生物风化成壤作用大于风尘堆积作用,为典型的黑垆土成壤期。从3 100 a B.P.开始,季风气候格局发生转变,气候干旱化,沙尘暴加剧,风尘堆积速率大于生物风化成壤速率,土壤资源自然退化,形成弱成壤层和黄土层,两层均属于全新世黄土L₀。先周时期耕作层对应古土壤层的顶部,土壤具有典型的团粒结构。3 100 a B.P.时的季风转变导致的气候干旱化与土壤退化促使了游牧民族南迁和"古公迁岐"事件的发生。     

Regime theories in gravel‐bed rivers: models,controlling variables,and applications in disturbed Italian rivers

Downstream hydraulic geometry relationships describe the shape of alluvial channels in terms of bankfull width, flow depth, flow velocity, and channel slope. Recent investigations have stressed the difference in spatial scales associated with these variables and thus the time span required for their adjustment after a disturbance. The aim of this study is to explore the consequences in regime models considering the hypothesis that while channel width and depth adjust quickly to changes in water and sediment supply, reach slope requires a longer time span. Three theoretical models were applied. One model incorporates an extremal hypothesis (Millar RG. 2005. Theoretical regime equations for mobile gravel‐bed rivers with stable banks. Geomorphology 64 : 207–220), and the other two are fully physically based (Ikeda S, Parker G, Kimura Y. 1988. Stable width and depth of straight gravel rivers with heterogeneous bed materials. Water Resources Research 24 : 713–722; Parker G, Wilcock PR, Paola C, Dietrich W, Pitlick J. 2007. Physical basis for quasi universal relations describing bankfull hydraulic geometry of single‐thread gravel‐bed rivers. Journal of Geophysical Research 112 , DOI: 10.1029/2006JF000549). In order to evaluate the performance of models introducing the slope as an independent variable, we propose two modifications to previous models. The performance of regime models was tested against published data from 142 river reaches and new hydraulic geometry data from gravel‐bed rivers in Patagonia (Argentina) and north‐eastern Italy. Models that assume slope as a control (Ikeda et al., 1988; or Millar, 2005) predict channel depth and width reasonably well. Parker et al.'s (2007) model improved predictions because it filters the scatter in slope data with a relation slope–discharge. The extremal hypothesis model of Millar (2005) predicts comparably to the other physically based models. Millar's model was chosen to describe the recent changes in the Piave and Brenta rivers due to human intervention – mainly in‐channel gravel mining. The change in sediment supply and recovery was estimated for these rivers. This study supports the interpretation that sediment supply is the key factor guiding morphological changes in these rivers. Copyright © 2013 John Wiley & Sons, Ltd.