Morphodynamics and sediment connectivity index in an unmanaged,debris-flow prone catchment: a through time perspective

Torrential processes are among the main actors responsible for sediment production and mobility in mountain catchments. For this reason, the understanding of preferential pathways for sediment routing has become a priority in hazard assessment and mitigation. In this context, the sediment Connectivity Index(IC) enables to analyse the existing linkage between sediment sources and the selected target(channel network or catchment outlet).The IC is a grid-based index that allows fast computation of ...     

A review of comminution age method and its potential application in the East China Sea to constrain the time scale of sediment source-to-sink process

The East China Sea(ECS) is a river-dominated epicontinental sea, linking the Asian continent to the northwestern Pacific via the large rivers originating from Tibetan Plateau. The relevant huge influx of riverine detritus has developed unique sedimentary systems in the ECS during the Quaternary, offering ideal terrestrial archives for reconstructing Quaternary paleoenvironmental changes and studying land-sea interactions. Overall, two characteristic river systems dominate the sedimentary systems and sediment source to sink transport patterns in the ECS, represented by the Changjiang(Yangtze River) and Huanghe(Yellow River) for the large river system and Taiwan rivers for the small river system. Given this, the sediments derived from both river systems bear distinct features in terms of parent rock lithology, provenance weathering and sediment transport. Previous studies mostly focus on either the ‘source' discrimination or the ‘sink' records of the sedimentary system in the ECS, while the source to sink process linking the land and sea, in particular its time scale, has been poorly understood. Here we introduce a newly-developed dating technique, the ‘comminution age' method, which offers a quantitative constraint on the time scale of sediment transfer from its ultimate source to the final depositional sink. This novel method is of great significance for improving our understanding on the earth surface processes including tectonic-climate driven weathering, and sediment recycling in relation to landscape evolution and marine environmental changes. The application of comminution age method in the ECS will provide important constraints on sediment source-to-sink process and more evidences for the construction of late Quaternary paleoenvironmental changes under these unique sedimentary systems.     

A Kinetic Spectrophotometric Method for the Determination of Iron （Ⅲ） in Water Samples

A new kinetic spectrophotometric method has been developed for the determination of iron (Ⅲ). The method is based on the catalytic effect of iron (Ⅲ) on the oxidation of weak acid brilliant blue dye (RAWL) by KIO4 in acid medium. The advantages of the proposed method are that it is sensitive, accurate, rapid, inexpensive, can be operated under room temperature and has a large determination concentration range compared to other techniques. The obtained optimum conditions are pH 3.15, RAWL (200 mgL-1) 5.00mL, Potassium periodate solution (0.01 molL-1) 0.30mL, phenanthroline (0.02molL-1) 1.00mL, reaction temperature 25℃ and reaction time 7 miu. With this method iron could quantitively be determined in the range 0.00-0.02 mgL-1, the detection limit being 4.10×10-10mL-1. The relative standard deviations (RSD) in five replicate determinations for 3 μgL-1 and 5μgL-1 iron (Ⅲ) are 3.1% and 1.9%, respectively. The method has been applied to the determination of iron (Ⅲ) in tap water samples and seawater samples (from the South China Sea), the recovery rates being 98.0% and 100.5%, respectively.     

A Modified Certainty Coefficient Method（M-CF） for Debris Flow Susceptibility Assessment：A Case Study for the Wenchuan Earthquake Meizoseismal Areas

In the meizoseismal areas hit by the China Wenchuan earthquake on May 12, 2008, the disasterprone environment has changed dramatically, making the susceptibility assessment of debris flow more complex and uncertain. After the earthquake, debris flow hazards occurred frequently and effective susceptibility assessment of debris flow has become extremely important. Shenxi gully in Du Jiangyan city, located in the meizoseismal areas, was selected as the study area. Based on the research of disaster-prone environment and the main factors controlling debris flow, the susceptibility zonations of debris flow were mapped using factor weight method（FW）, certainty coefficient method（CF） and geomorphic information entropy method（GI）. Through comparative analysis, the study showed that these three methods underestimated susceptible degree of debris flow when used in the meizoseismal areas of Wenchuan earthquake. In order to solve this problem, this paper developed a modified certainty coefficient method（M-CF） to reflect the impact of rich loose materials on the susceptible degree of debris flow. In the modified method, the distribution and area of loose materials were obtained by field investigations and postearthquake remote sensing image, and four data sets, namely, lithology, elevation, slop and aspect, wereused to calculate the CF values. The result of M-CF method is in agreement with field investigations and the accuracy of the method is satisfied. The method has a wide application to the susceptibility assessment of debris flow in the earthquake stricken areas.     

A new method for the estimation of fine-sediment resuspension ratios in estuaries-taking the turbidity maximum zone of the Changjiang(Yangtze) estuary as an example

Based on the principle of conservative matter removal in estuary,a new method is proposed for estimating the ratio of sediment resuspension in estuaries with fine suspended sediments in the turbidity maximum zone(TMZ) of the Changjiang(Yangtze) estuary during 2005.Results show that there was a range of 18.7%±27.9% to 73.9%±22.5% per annum of total suspended particulate matter(SPM),with an average of 49.2%.Nearly half of the particulate matter in the TMZ originates from sediment resuspension.This indicates that sediment resuspension is one of the major mechanisms involved in formation of the TMZ.Compared with traditional method for calculating these ratios in the estuary,this new method evaluates the dynamic variation of SPM content carried by river runoff from the river mouth to the ocean.The new method produced more reliable results than the traditional one and could produce a better estimation of resuspension flux for particulate matter in estuaries.     

A dynamic model for exploring water-resource management scenarios in an inland arid area: Shanshan County,Northwestern China

Water scarcity is a challenge in many arid and semi-arid regions; this may lead to a series of environmental problems and could be stressed even further by the effects from climate change. This study focused on the water resource management in Shanshan County, an inland arid region located in northwestern China with a long history of groundwater overexploitation. A model of the supply and demand system in the study area from 2006 to 2030, including effects from global climate change, was developed using a system dynamics (SD) modeling tool. This SD model was used to 1) explore the best water-resource management options by testing system responses under various scenarios and 2) identify the principal factors affecting the responses, aiming for a balance of the groundwater system and sustainable socio-economic development. Three causes were identified as primarily responsible for water issues in Shanshan: low water-use efficiency, low water reuse, and increase in industrial water demand. To address these causes, a combined scenario was designed and simulated, which was able to keep the water deficiency under 5% by 2030. The model provided some insights into the dynamic interrelations that generate system behavior and the key factors in the system that govern water demand and supply. The model as well as the study results may be useful in water resources management in Shanshan and may be applied, with appropriate modifications, to other regions facing similar water management challenges.     

The critical stage for inducing oviparity and embryonic diapause in parthenogenetic Artemia(Crustacea: Anostraca): an experimental study

The brine shrimp Artemia exhibits two reproductive modes:1)oviparity,producing diapause embryos;and 2)ovoviviparity,producing free-swimming nauplii.Previous studies have suggested the existence of a critical stage that determines the reproductive mode.Physicochemical factors,such as photoperiod,temperature,and salinity,have been suggested to irreversibly affect the reproductive mode of oocytes during this critical stage.In this study,experiments were carried out using a photoperiod and temperature-sensitive parthenogenetic Artemia clone where maternal Artemia were shifted bidirectionally between ovoviviparity(18 h L:6 h D,27℃)and oviparity(6 h L:18 h D,19℃)culture conditions.In the main experiment(Artemia shifted at six different stages including the post-larva Ⅱ to adult Ⅱ),the reproductive mode of first brood was converted when shifting was performed on post-larva II and III but was not converted when females were shifted after post-larva Ⅲ.A supplementary experiment further revealed that the reproductive mode of first brood could be altered when shifting females at an "early phase of postlarva Ⅳ",characterized by a developing ovisac reaching the middle of the third abdominal segment,ventral spines,and some oocytes growing larger than the others.In both experiments,reproductive modes of the second brood were significantly affected when the shifting was performed on post-larva Ⅳ.These results suggest that the critical stage for inducing oviparity and embryonic diapause is at the previtellogenic stage of oocytes,or at maternal "early phase of post-larva Ⅳ" for the first-brood offspring.During this stage,differential gene expression patterns of the two destined oocytes may be triggered by the token stimuli signals received by the oocytes.     

Review of Global Ocean Intermediate Water Masses： 1. Part A, the Neutral Density Surface （the ＇McDougall Surface＇ ） as a Study Frame for Water-Mass Analysis

This review article commences with a comprehensive historical review of the evolution and application of various density surfaces in atmospheric and oceanic studies. The background provides a basis for the birth of the neutral density idea. Attention is paid to the development of the neutral density surface concept from the nonlinearity of the equation of state of seawater. The definition and properties of neutral density surface are described in detail as developed from the equations of state of seawater and the buoyancy frequency when the squared buoyancy frequency N2 is zero, a neutral state of stability. In order to apply the neutral density surface to intermediate water-mass analysis, this review also describes in detail its practical oceanographic application. The mapping technique is focused for the first time on applying regularly gridded data in this review. It is reviewed how a backbone and ribs framework was designed to flesh out from a reference cast and first mapped the global neutral surfaces in the world＇s oceans. Several mapped neutral density surfaces are presented as examples for each world ocean. The water-mass property is analyzed in each ocean at mid-depth. The characteristics of neutral density surfaces are compared with those of potential density surfaces.     

Effect of diurnal temperature difference on lipid accumulation and development in Calanus sinicus(Copepoda:Calanoida)

Calanus sinicus,the dominant copepod in the Yellow Sea,develops a large oil sac in late spring to prepare for over-summering in the Yellow Sea Cold Water Mass(YSCWM).The lipid accumulation mechanism for the initiation of over-summering is unknown.Here,we cultured C3 copepodites at four constant temperatures(10,13,16,and 19℃) and at three temperature regimes that mimicked the temperature variations experienced during diurnal vertical migration(10-13℃,10-16℃,and 10-19℃) for 18 days to explore the effects of temperature differences on copepod development and lipid accumulation.C.sinicus stored more lipid at low than at high temperatures.A diurnal temperature difference(10-16℃ and 10-19℃)promoted greater lipid accumulation(1.9-2.1 times) than a constant temperature of either 16℃ or 19℃,by reducing the energy cost at colder temperatures and lengthening copepodite development.Thereafter,the lipid reserve supported gonad development after final molting.Only one male developed in these experiments.This highly female-skewed sex ratio may have been the result of the monotonous microalgae diet fed to the copepodites.This study provides the first evidence that diurnal temperature differences may promote lipid accumulation in C.sinicus,and provides a foundation for future investigations into the mechanisms involved in over-summering in the YSCWM.     

A method of catchments health assessment under value-pressure model and its application in urbanized river network area: A case study in Shanghai,China

Catchments health assessment is fundamental to effective catchments management. Generally, an as-sessment method should be selected to reflect both the purpose of assessment and local characteristics. A trial in Shanghai was conducted to test the method for catchments health assessment in urbanized river network area. Seven indicators that described four dimensions of river, river network, land use and function, and local feature were used to assess catchments values; while possible change rate of urbanization and industrialization in the next 3 years were chosen for catchments pressure assessment in the value-pressure model. Factors related to catchments classi-fication, indicators measurement and protection priority have been considered in the development strategies for catchments health management. The results showed that value-pressure assessment was applicable in urbanized catchments health management, particularly when both human and catchments had multiple demands. As a result of over 30-year rapid urbanization, more than 70% of Shanghai river network area was still in a healthy condition with high catchments values, among them, 39.3% was under high pressure. Poor water quality, simplified river system and weakened local feature of river pattern had largely affected catchments health in Shanghai. Lack of long-term monitoring data would seriously restrict the development and validity of catchments health assessment.     

Using uncertainty and sensitivity analysis for finding the best rainfall-runoff model in mountainous watersheds(Case study: the Navrood watershed in Iran)

In watersheds that have not sufficient meteorological and hydrometric data for simulating rainfall-runoff events, using geomorphologic and geomorphoclimatic characteristics of watershed is a conventional method for the simulation. A number of rainfall-runoff models utilize these characteristics such as Nash-IUH, Clark-IUH, Geomorphologic Instantaneous Unit Hydrograph(GIUH), Geomorphoclimatic Instantaneous Unit Hydrograph(GcIUH), GIUH-based Nash(GIUH-Nash) and GcIUH-based Clark(GcIUH-Clark). But all these models are not appropriate for mountainous watersheds. Therefore, the objective of this study is to select the best of them for the simulation. The procedure of this study is: a) selecting appropriate rainfall-runoff events for calibration and validation of six hybrid models, b) distinguishing the best model based on different performance criteria(Percentage Error in Volume(PEV); Percentage Error in Peak(PEP); Percentage Error in Time to Peak(PETP); Root Mean Square Error(RMSE) and Nash-Sutcliffe model efficiency coefficient(ENS)), c) Sensitivity analysis for determination of the most effective parameter at each model, d) Uncertainty determination of different parameters in each model and confirmation of the obtained results by application of the performance criteria. For application of this procedure, the Navrood watershed in the north of Iran as a mountainous watershed has been considered. The results showed that the ClarkIUH and GcIUH-Clark are suitable models for simulation of flood hydrographs, while other models cannot simulate flood hydrographs appropriately. The sensitivity analysis shows that the most sensitive parameters are the infiltration constant rate and time of concentration in the Clark-IUH model. Also, the most sensitive parameters include the infiltration constant rate and storage coefficient in the GcIUHClark model. The Clark-IUH and GcIUH-Clark models are more sensitive to their parameters. The Latin Hypercube Sampling(LHS) on Monte Carlo(MC) simulation method was used for evaluation of uncertainty of data in rainfall-runoff models. In this method 500 sets of data values are produced and then the peak discharge of flood hydrographs for each produced data set is simulated with rainfall-runoff models. The uncertainty of data changes the value of simulated peak discharge of flood hydrograph. The uncertainty analysis shows that the observed peak discharges of different rainfall-runoff events are within the range of values of simulated by the six hybrid rainfall-runoff models and IUH that inputs of these models were the produced data sets. The range of the produced peak discharge of flood hydrographs by the Clark-IUH and GcIUH-Clark models is wider than those of other models.     

A sand control and development model in sandy land based on mixed experiments of arsenic sandstone and sand: A case study in Mu Us Sandy Land in China

Serious desertification caused by human activity and climate change, in addition to water loss and soil erosion related to arsenic sandstone in the Mu Us Sandy Land, lead to severe scarcity of soil and water resources, which causes worse local agricultural conditions accordingly. Many physical properties of arsenic sandstone is complementary with that of sand, arsenic sandstone is therefore supposed to be blended to enhance water productivity and arability of sandy land. Container experiments are carried out to study the enhancement of water holding capacity of the mixture, the blending ratio of arsenic sandstone and sand, and the proper size of the arsenic sandstone particles, respectively. The results of the experiments show that particle size of 4 cm with a ratio of 1 ： 2 between arsenic sandstone and sand are the proper parameters on blending. Both water content and fertility increase after blending. Water use efficiency in the mixture is 2.7 times higher than that in sand by the water release curves from experiments. Therefore, a new sand control and development model, including arsenic sandstone blending with sand, efficient water irrigation management and reasonable farming system, is put forward to control and develop sandy land so that water-saving agriculture could be developed. Demonstration of potato planting about 153.1 ha in area in the Mu Us Sandy Land in China indicates that water consumption is 3018 m3/ha in the whole growth period. It means that about 61% of irrigation water can be saved compared with water use in coarse sand without treatment. Recycle economic mode and positive feedback of sand resource-crop planting-soil resource are constructed, which changes sand into arable soil and make it possible to develop water-saving agriculture on it. The proposed model will be helpful for soil-water resources utilization and management in the Mu Us Sandy Land.     

Settlement and metamorphosis of Rapana venosa (Gastropoda: Muricidae) with implications for artificial culture

Journal of Oceanology and Limnology - The rapa whelk Rapana venosa transforms from a phytophagous larva to a carnivorous juvenile after settlement and metamorphosis. The high mortality rate and low...     

Evaluation of Ordinary Least Square (OLS) and Geographically Weighted Regression (GWR) for Water Quality Monitoring: A Case Study for the Estimation of Salinity

Landsat-5 Thematic Mapper (TM) dataset have been used to estimate salinity in the coastal area of Hong Kong. Four adjacent Landsat TM images were used in this study, which was atmospherically corrected using the Second Simulation of the Satellite Signal in the Solar Spectrum (6S) radiative transfer code. The atmospherically corrected images were further used to develop models for salinity using Ordinary Least Square (OLS) regression and Geographically Weighted Regression (GWR) based on in situ data of October 2009. Results show that the coefficient of determination (R²) of 0.42 between the OLS estimated and in situ measured salinity is much lower than that of the GWR model, which is two times higher (R² = 0.86). It indicates that the GWR model has more ability than the OLS regression model to predict salinity and show its spatial heterogeneity better. It was observed that the salinity was high in Deep Bay (north-western part of Hong Kong) which might be due to the industrial waste disposal, whereas the salinity was estimated to be constant (32 practical salinity units) towards the open sea.     

A light and transmission electron microscopic study ofHexamite capsularis sp. nov. (Diplomonadina: Hexamitidae) in fish (Xenocypris dividi)

A diplomonad flagellateHexamita capsularis sp. nov. from the posterior intestine of the fish (Xenocypris dividi) from Liangzi Lake, Hubei Province, is described. The flagellate was oval, with smooth surface and homogenous cytoplasm, 6.21±0.28 μm in length, 3.43±0.48 μm in width and with an elliptical capsule. Two recurrent flagellae arranged between two nuclei ran longitudinally to the posterior end. Fibrillar bands connected the accessory organelles of two cytostomal tubes, the body depressed at the posterior end of the body. This work is a part of the M. S. thesis of Xiao Wu-han and was supported by the National Natural Science Foundation of China (Grant No. 3870489).     

Wave-current interaction during Typhoon Nuri (2008) and Hagupit (2008):an application of the coupled ocean-wave modeling system in the northern South China Sea

The northern South China Sea(SCS) is frequently affected by typhoons. During severe storm events, wave-current interactions produce storm surges causing enormous damage in the path of the typhoon. To evaluate the influence of wave-current interactions on storm surge, we used a coupled ocean-atmospherewave-sediment transport(COAWST) modeling system with radiation-stress and vortex-force formulations to simulate two typically intense tropical storms that invaded the SCS, namely Typhoons Nuri(2008) and Hagupit(2008), and compared results with observations from the Hong Kong Observatory. Both radiationstress and vortex-force formulations significantly improved the accuracy of the simulation. Depending on which typhoon and the topography encountered, the influence of surface waves on the oceanic circulation showed different characteristics, including the differences of range and intensity of storm surge between vortex-force and radiation-stress experiments. During typhoon landing, strong sea-surface elevation in concert with wave set-up/set-down caused the adjustment of the momentum balance. In the direction perpendicular to the current, but especially in the cross-shore direction, the pressure gradient and wave effects on the current dominated the momentum balance.     

Complementary DNA sequencing (cDNA): an effective approach for assessing the diversity and distribution of marine benthic ciliates along hydrographic gradients

The Yellow Sea Cold Water Mass(YSCWM) is a distinct hydrographic phenomenon of the Yellow Sea,and the distribution pattern of meio-and macrobentho s diffe rs inside and outside of the YSCWM.However,such a pattern has never been observed in the microbenthic ciliate communities.Therefore,we hypothesized that benthic ciliates followed a similar distribution pattern as meio-and macrobentho s,but this pattern has not been uncovered by morphological methods.We evaluated the diversity and distribution of benthic ciliates at five stations along hydrographic gradients across the YSCWM and adj acent shallow water by using morphology and DNA and complementary DNA(cDNA) high-throughput sequencing of the V4 region of 18 S rRNA gene.Results showed that the diversity of benthic ciliate s detected by DNA(303 OTU s),and the cDNA(611 OTUs) sequencing was much higher than that detected by the morphological method(79 species).Morphological method detected roughly different ciliate communities inside and outside of the YSCWM,but without statistical significance.No clear pattern was obtained by DNA sequencing.In contrast,cDNA sequencing revealed a distinct distribution pattern of benthic ciliate communities like meioand macrobenthos,which coincided well with the results of the environmental parameter analysis.More than half of the total sequences detected by DNA sequencing belonged to planktonic ciliates,most(if not all) of which were recovered from historic DNA originating through the sedimentation of pelagic forms because none of them were observed morphologically.The irrelevant historic DNA greatly influenced the recovery of rare species and thus limited the understanding of the benthic ciliate diversity and distribution.Our research indicates that the methods used have significant effects on the investigation of benthic ciliate communities and highlights that cDNA sequencing has great advantages in estimating the diversity and distribution of benthic ciliates,as well as the potential for benthic environmental assessments.     

Cross-national Perspectives on Using Sustainable Development Goals(SDGs) Indicators for Monitoring Sustainable Development: A Database and Analysis

Sustainable development is the theme of the 21st century. To monitor the progress of sustainable development, the United Nations launched Sustainable Development Goals(SDGs) in 2015. Subsequently, nations of the world have drawn up a list of localized indicators regarding the United Nations SDGs as a paradigm. We established a database including SDGs indicator systems of 11 economies by collecting and determining a large number of materials. Based on this database, we analyzed SDGs indicators by...     

Impact of Colonization of an Invasive Species on Genetic Differentiation in New Environments: A Study on American Artemia franciscana(Crustacea: Anostraca) in the United Arab Emirates

Artemia franciscana, native to America, has recently colonized as non-indigenous population in Asia, Europe, North Africa, and Australia. We evaluated the effects of the colonization of A. franciscana on genetic differentiation in new environments in the United Arab Emirates(UAE). We used the COI marker to determine the genetic structure and origins of exotic populations in the UAE. Results confirmed the colonization of A. franciscana in two localities. Invasive populations of A. franciscana had significantly lower genetic variation than native populations in the Great Salt Lake and San Francisco Bay. Results showed that the studied populations could not have colonized directly from natural American habitats, and they possibly were from secondary introduction events of other non-indigenous populations. Genetic analysis yielded different demographic patterns for the studied invasive populations. The population in Al Wathba Wetland Reserve(AWWR) demonstrated demographic expansion, whereas in Godolphin Lakes(GL), it reached a demographic equilibrium. Neutrality tests showed an excess of recent and historical mutations in the COI gene pool of invasive AWWR Artemia in the new environment. The results suggest that different ecological conditions in new environments can exert selective pressures during the introduction of an exotic population, which can affect genetic variation.     

Evapotranspiration Estimation Based on MODIS Products and Surface Energy Balance Algorithms for Land （SEBAL） Model in Sanjiang Plain, Northeast China

In this study,the Surface Energy Balance Algorithms for Land(SEBAL) model and Moderate Resolution Imaging Spectroradiometer(MODIS) products from Terra satellite were combined with meteorological data to estimate evapotranspiration(ET) over the Sanjiang Plain,Northeast China.Land cover/land use was classified by using a recursive partitioning and regression tree with MODIS Normalized Difference Vegetation Index(NDVI) time series data,which were reconstructed based on the Savitzky-Golay filtering approach.The MODIS product Quality Assessment Science Data Sets(QA-SDS) was analyzed and all scenes with valid data covering more than 75% of the Sanjiang Plain were selected for the SEBAL modeling.This provided 12 overpasses during 184-day growing season from May 1st to October 31st,2006.Daily ET estimated by the SEBAL model was misestimaed at the range of-11.29% to 27.57% compared with that measured by Eddy Covariance system(10.52% on average).The validation results show that seasonal ET from the SEBAL model is comparable to that from ground observation within 8.86% of deviation.Our results reveal that the time series daily ET of different land cover/use increases from vegetation on-going until June or July and then decreases as vegetation senesced.Seasonal ET is lower in dry farmland(average(Ave):491 mm) and paddy field(Ave:522 mm) and increases in wetlands to more than 586 mm.As expected,higher seasonal ET values are observed for the Xingkai Lake in the southeastern part of the Sanjiang Plain(Ave:823 mm),broadleaf forest(Ave:666 mm) and mixed wood(Ave:622 mm) in the southern/western Sanjiang Plain.The ET estimation with SEBAL using MODIS products can provide decision support for operational water management issues.