Analysis on Suspended Sediment Deposition Rate for Muddy Coast of Reclaimed Land

A new expression for calculating suspended fine-sediment deposition rate is developed based on theoretic analysis and experiments. The resulting equation is applied to simulation of fine sediment deposition in the reclaimed land in the Hangzhou Bay, China. The hydrodynamic environment in this area is solved by use of a long wave model, which gives the 2D-velocity field and considers bathymetric changes due to fine sediment deposition. The expression is proved convenient to use in engineering practice, and the predicted deposition rate agrees with the annual data available from field measurements from the first year to the third year after the construction of the long groin as a reclaiming method.

Numerical simulation of sediment deposition thickness at Beidaihe International Yacht Club

The finite element method （FEM） was used to simulate sediment hydrodynamics at the Beidaihe International Yacht Club, and a two-dimensional model was established. The sediment movement and deposition were analyzed under many tidal conditions in conjunction with the hydrological regime of the Daihe River. The peak value of the sediment deposition thickness appears in the main channel and around the estuary. The sediment deposition thickness is essentially constant and relatively small in the project area. The sediment deposition thickness in the main channel, in the yachting area, and around the hotel is greater than the other areas in the project. Regular excavation and dredging of the channel is the best measure for mitigating the sedimentation.

Effects of an oasis protective system on aeolian sediment deposition:a case study from Gelintan oasis,southeastern edge of the Tengger Desert,China

Desert-oasis ecotones are boundary areas between oases and desert ecosystems.Large efforts to control sediment and stabilize these boundaries depend on understanding sedimentary processes,especially aeolian transport and deposition.Previous studies on aeolian sediment deposition have focused primarily on a single land surface type or a single engineering approach.Few studies have considered deposition in a multi-layer oasis protective system.A complete oasis protective system consists of an outer bare sand area,a sand barrier zone,a shrub and herbaceous plant zone,and a farmland shelter zone.This study used sedimentary analysis to quantify grain-size characteristics in samples from the four land surfaces under different types of weather conditions in the Gelintan oasis of the Tengger Desert,the fourth largest desert in China.The results showed that aeolian sediment deposition decreased from the outer bare sand area through the oasis protective system and into the interior.The four land surface types showed significant differences in deposition volume(P<0.05).Deposited sediment showed gradual decrease in dominant grain-size from sand to silt,but sediment deposited during dust weather contained a larger coarse-grained fraction.From the outer desert to the inner oasis,transport mechanisms shifted from saltation(sand)to suspension(silt and smaller)in non-dust weather.During dust weather,deposition primarily occurs from near-surface aeolian sand transport with saltation.Sediment sorting decreased from exterior to interior zones of the protective system while skewness and kurtosis showed no significant change(P<0.05).These results can help inform strategies for stabilizing and protecting desert-oasis ecotones in this region and other localities.

Influencing factors of sediment deposition and their spatial variability in riparian zone of the Three Gorges Reservoir,China

Many factors can affect the sediment deposition and soil erosion process in riparian zone, including terrain, sediment transport and water level fluctuations. Clarifying the factors influencing sediment deposition process in the riparian zone of the Three Gorges Reservoirs is an important problem to determine the key area of sediment deposition and its trend of development in the study area. In order to reveal the influence of these environmental factors on the sediment deposition in riparian zone of the Three Gorges Reservoir, this study investigated 1) the amount of deposited sediment in different environmental conditions, 2) the potential factors affecting sediment deposition in riparian zone of the Three Gorges Reservoir, 3) the relationship between the deposited sediment amount and these factors previously mentioned using correlation analysis, and 4) the influence of human activities considered as an additional factor. This study found that 1) slope gradient, elevation, inundating duration and human activities were the main factors influencing sedimentation in riparian zone of the Three Gorges Reservoir, and 2) the impact of each factor varied with spaces. Specifically, in the upper reach from Jiangjin to Fuling, human activities such as gravel dredging, bank revetment and ports and wharfs constructing disturbed considerable amounts of deposited sediment, as a result, there was no natural law to dictate the distribution. In the middle reach from Fuling to Fengjie, slope gradient and inundating duration were the controlling factors, and the sediment deposition amount was greater in the areas with a gentler slope or lower elevation. Water flow on gentler slopes generally had lower velocity, resulting in more sediment to deposit. Sites with lower elevations would be drowned by sediment-laden flow with a longer duration resulting from hydrologic regime controlled by the operating strategy of the Three Gorges Reservoir, leading to a larger amount of sediment deposition. In the lower reach from Fengjie to Zigui, slope gradient was similar to the middle reach, performing a primary factor, while other factors showed little relationship with sediment amount.

Sediment Deposition and Resuspension in Mouth Bar Area of the Yangtze Estuary

A comprehensive analysis is conducted based on observations on topography, tidal current, salinity, suspended sediment and bed load during the years of 1982, 1983, 1988, 1989. 1996, and 1997 in the Yangtze Estuary. Results show that the deformation of tidal waves is distinct and the sand carrying capacity is large within the mouth bar due to strong tidal currents and large volume of incoming water and sediments. Owing to both temporal and spatial variation of tidal current, deposition and erosion ore extremely active. In general a change of up to 0.1 m of bottom sediments takes place during a tidal period. The maximum siltation and erosion are around 0.2 m in a spring to neap tides cycle. The riverbed is silted during flood when there is heavy sediment load, eroded during dry season when sediment lo:ld is low. The annual average depth of erosion anti siltation on the riverbed is around 0.6 m. In particular cases, it may increase to 1.4 m to 2.4 m at some locations.

The analysis on reservoir sediment deposition and downstream river channel scouring after impoundment and operation of TGP

According to the measured data after impoundment and operation of the Three Gorges Reservoir,the reservoir sediment deposition and downstream river channel scouring are described briefly and compared with the research results achieved in the demonstration stage.It is indicated through analysis that the reservoir sediment deposition and downstream river channel scouring during 8-year impoundment and operation are still within the original forecast,so the original forecasting results are feasible.The further observation and comparison should be conducted because the comparison between the observed data and the original forecast is not so sufficient in time and the prototype observation and related research work should be strengthened in the future.

Local hydraulic jump effects on sediment deposition in open-channel flume experiments

When a river channel is narrow,bifurcated,or intersected,or when extreme weather or geological disasters cause shed rock masses to occupy a river flood channel,local hydraulic jumps may develop in the channel.Natural disasters such as landslides,floods,and debris flows occur upstream,will result in large transport rate of large-sized gravel particles.Those particles may be blocked in hydraulic jump areas,causing river channel water depth to rise.In this study,the effect of local hydraulic jumps on the sediment deposition rate was investigated in flume experiments.The ratio of upstream and downstream Froude numbers,particle size,Sediment supply intensity,and flow discharge all affected the sediment deposition rate.With increases in the ratio of upstream and downstream Froude numbers,particle size,and sediment supply intensity,the sediment deposition rate increased.The sediment deposition rate decreased with an increase in flow discharge.Approach hydraulic conditions and particle properties jointly determined the sediment deposition rate in a hydraulic jump section,and an empirical formula was developed using those parameters to calculate the sediment deposition rate.Thus,to identify risks and prevent disasters in mountain rivers,local changes in hydraulic conditions and particle properties need to be jointly evaluated.

Chemical Determination of Base Status Metals in Soil Sediments and Particulate Matter in Wellington Industrial Estate Location

This research study explored the levels of base status metals in soil sediments and particulate matter in the wellington industrial estate location;the main objectives were to: 1) determine sodium and potassium, 2) determine calcium and magnesium, 3) determine available iron. The following hypotheses were put forward;H0a: there is no significant difference in the concentration levels between Ca and Mg in the study area, H1a: there is significant difference in the concentration levels between Ca and Mg in the study area, H0b: there is no significant difference in the concentration levels between Na and K in the study area, H1b: there is significant difference in the concentration levels between Na and K in the study area. Six locations were used to collect samples with the aid of scoop and gravel free auger (at varying depths of 0 - 5 cm and 5 - 10 cm) which are Wellington Industrial Estate Area 1 (WIEL 1), (WIEL 2), (WIEL 3), (WIEL 4), (WIEL 5), (WIEL 6);the samples were given laboratory treatment. Flame photometer, EDTA, and Spectrophotometer were used in the determinations of sodium and potassium, calcium and magnesium, and available iron respectively. The results indicated that levels of potassium were in medium range (moderately high);sodium levels were generally low when compared to Brook’s classification table. Levels of calcium were generally low and those of magnesium were moderate based on Brook’s table of classification. Levels of available iron which fall within the range of Quijano-Guerta (2003) were high;this implies such levels can lead to toxicity. In all locations, there was decrease in the levels of each metal in the samples with (5 - 10 cm) depth.

Application of a ^(137)Cs fingerprinting technique for interpreting responses of sediment deposition of a karst depression to deforestation in the Guizhou Plateau,China

Deforestation to reclaim land often triggers severe soil erosion in the Guizhou Karst Plateau. 137Cs dating of the deposited sediments in the karst depression bottom was used to estimate soil losses by surface erosion since deforestation started in 1979 on hillslopes in the Shirenzhai catchment, Puding County, Guizhou Province. The catchment has a drainage area of 0.054 km2. The average 137Cs contents of the top and peak layers in five cores of the depression bottom (with an area of 2652 m2), collected in 2009, were 2.35 and 7.25 Bq kg-1, respectively. The medium depths in the depression (which ranged between 84 cm and 113.5 cm with a mean value of 92.1 cm) showed the presence of sediments deposited in 1979. The total volume and weight of the deposited sediments since 1979 were estimated to be 1965 m3 and 2496 t, respectively. The depression bottom can be treated as a temporary impoundment and its sediment trapping efficiency was estimated to be 0.7. The relevant average soil erosion rate on the hillslopes was 2315 t km-2 yr-1 since 1979. The mean 137Cs inventory of the five cores was 7693 Bq m-2, which was ~10 times the local reference inventory of 782 Bq m-2. The total 137Cs activity of the sediments in the bottom was 20.4×106 Bq, and the relevant 137Cs inventory loss from the hillslopes was 358 Bq m-2 (since 1954), which accounted for 45.8% of the reference inventory. As soil erosion was not severe before and after the period of deforestation and following cultivation in 1979-1990, the erosion rates on the hillslopes could potentially reach 7000 t km-2 yr-1.

Concentrations and chemical forms of potentially toxic metals in road-deposited sediments from different zones of Hangzhou, China

The 25 road-deposited sediments were collected from five different land-use zones （industrial, residential, commercial, park, and countryside） in Hangzhou, China. The concentrations of metals （Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn） in these samples were determined using ICP-AES after digestion with the mixture of HNO3-HF-HC1 （aqua regia）, and chemically fractionated according to the modified BCR （the European Community Bureau of Reference） sequential extraction procedure. The high metal concentration levels were detected in the sample from industrial zone and commercial zone having heavy traffic. While the low metal levels were noted in the street dust sample from residential zone, park, and countryside zone. The mobility sequence based on the sum of the BCR sequential extraction stages was： Zn （80.28%）, Pb （78.68%）, Cd （77.66%） 〉 Cu （73.34%） 〉 Mn （67.92%） 〉 Co （41.66%） 〉 Ni （30.36%） 〉 Cr （21.56%）, Fe （20.86%）. Correlation analysis and principal component analysis were applied to the data matrix to evaluate the analytical results and to identify the possible pollution sources of metals. Factor analysis showed that these areas were mainly contaminated by three sources, namely lithology, traffic, and industry.

Deposited sediment settlement and consolidation mechanisms

In order to study deposited sediment settlement and consolidation mechanisms, sediment settlement experiments were conducted using a settlement column. Based on the experimental results, sediment settlement stage definition, excessive pore pressure （EPP） dissipation, and consolidation constitutive equations are discussed. Three stages, including the free settlement, hindered settlement, and self-weight consolidation settlement stages, are defined. The results of this study show that sediment settlement is mainly affected by the initial sediment concentration and initial settlement height, and the interface settlement rate is linearly attenuated with time on bilogarithmic scales during the hindered settlement and self-weight consolidation settlement stages. Moreover, the deposited sediment layer in the self-weight consolidation settlement stage experiences large strains, and the settlement amount in this stage is about 32% to 59% of the initial height of deposited sediment. EPP is nonlinearly distributed in the settlement direction, and consolidation settlement is faster than EPP dissipation in the self-weight consolidation settlement stage. Consolidation constitutive equations for the hydraulic conductivity and effective stress, applicable to large-strain consolidation calculation, were also determined and fitted in the power function form.

Fabrication and Characterization of Ni-Al_2O_3 Nano-Composite Coatings by Sediment Co-Deposition

Ni-Al2O3 nano-composite coatings were fabricated by sediment co-deposition (SCD) from Watt’s type electrolyte containing nano-Al2O3 particles without any additives. For comparison, Ni-Al2O3 nano-composite coatings were prepared by conventional electro-plating (CEP) under experimental conditions. Effects of process parameters, such as nano-Al2O3 concentration in plating solution, current density, stirring rate, and bath temperature, on nano-Al2O3 content in composite coatings were investigated. The distribution of elements in deposit, and the bonding strength between coating and substrate was analyzed by electron probe microanalyzer (EPMA) and auto-scratch apparatus, respectively. It is found that the nano-Al2O3 concentration in plating solution, current density and stirring rate are three main factors affecting the particles content in deposit, and played a key role in the formation of composite coatings. The nano-Al2O3 content in composite coatings increased with increasing of nano-Al2O3 concentration in plating solution, current density and stirring rate to reach a maximum value, and then reduced slightly. The contents of nano-Al2O3 particles in composite coatings by the SCD technique were higher than that by the CEP technique. The co-deposited nano-Al2O3 particles embedded uniformly in the Ni matrix. The coating was well adhesion with substrate. It is demonstrated that the SCD technique is an efficient approach for improving the nano-Al2O3 content in Ni-Al2O3 composite coatings.

Grain-size Characteristics of Sediment in Daniugou Peatland in Changbai Mountains,Northeast China:Implications for Atmospheric Dust Deposition

The grain-size distribution characteristics and grain-size parameters of sediment in two vertical sections of Daniugou peatland in the Changbai Mountains were systematically investigated.A comparative analysis of the sediment granularity using a discriminative function with Hongyuan peat,red clay,loess-paleosol,fluvial deposit as well as lacustrine deposit was also conducted.It turns out that the vertical section of Daniugou peat ash is primarily constituted by clay and silt particles,and the content of sand is relatively small.Grain-size frequency curves generally show a single-peak modality while a bimodal pattern is detected in the upper layer.The grain-size component and peak pattern of grain-size frequency curves also illustrate that peat ash materials were transported to the peatland by long-range aeolian dust during the deposition process,while there existed short-distance dust influence in peat deposition of the upper layer.Comparisons of grain-size parameters and the discriminative Y-value of Daniugou peat ash with those of typical aeolian sediments show close similarities,suggesting the possibility that atmospheric dust transport processes were involved in the accumulation of peat again.Moreover,the variations of grain-size distribution suggest the local environmental deterioration which is just the driving force of local dust elevation.Grain-size analysis of peatland sediment is demonstrated to be one effective method to extract information about regional and global environmental evolution,and more attention should be paid to current local ecological environment and to seeking a balance between economic development and environmental protection in Northeast China.

Lincang Superlarge Germanium Deposit in Yunnan Province,China: Sedimentation,Diagenesis,Hydrothermal Process and Mineralization

The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements and huminite reflectance. It is concluded that the source of Lincang superlarge deposit is mainly the muscovite granite in the west edge of the basin. During sedimentation, Ge (germanium) was leached out and entered the basin. Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes: peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO 2- 4 was reduced by coal organic matter. Pyrite and calcite formed. Hydrothermal process did not contribute significantly to mineralization.

Sediment-hosted Pb-Zn Deposits in Southwest Sanjiang Tethys and Kangdian Area on the Western Margin of Yangtze Craton

The western margin of Yangtze Craton is known as a significant sediment-hosted base-metal aggregate cluster,especially for Pb-Zn deposits in China,e.g.Jinding,Daliangzi,Tianbaoshan, Kuangshanchang and Qinlinchang deposits.In comparison with the classic MVT deposits in the world, based on the basic geology of the sediment-hosted Pb-Zn deposits,this paper focuses on temporal-spatial distribution of this deposit to further discuss its large scale mineralization and tectonic evolution history.In the SW Sanjiang Thethys,Jinding deposit is typically thrust fault-controlled and hosted mainly in the sandstones and breccia-bearing sandstones,whereas MVT-type deposits are controlled by lithology and faulting/fracturing with a strong preference for carbonate-hosted rocks.Most importantly,Jinding Pb-Zn deposit differs from the other types of sediment-hosted Pb-Zn deposits in which it was formed in a strongly deformed foreland basin within a continental collision zone.In the Kangdian area,the sediment-hosted Pb-Zn deposits were formed in the extensional basin on the side of the continental orogenic belt along the Yangtze Craton.Compared with classic MVT deposits,the Pb-Zn deposits in the Kangdian area belong to MVT deposits.This paper is significant not only for interpretation of the genesis of sediment-hosted Pb-Zn deposits but also for exploiting large base metal deposits in large sedimentary target areas.

Organic Geochemistry of Sedimentary Rock-hosted Disseminated Gold Deposits in Southwestern Guizhou Province, China

Sedimentary rock-hosted disseminated gold (SRHDG) deposits in the Youjiang-Nanpanjiang Basin, southwestern Guizhou Province are commonly hosted by the same fold crests that commonly contain a remarkable amount of organic material. The total organic carbon (TOC) contents of the ores and host rocks are usually less than 1%. The reflectance of vitrinite and pyrobitumen in the ores and the host rocks ranges from 1.5% to 4.5%, often in the range of 2% to 3%. In the Lannigou deposit, the reflectance of vitrinite and pyrobitumen in the ores is usually somewhat higher than those within the host rocks, indicating a hydrothermal impact on the organic matter in the altered host rocks. On the contrary, the estimated maximum paleotemperatures of the Getang and Zimudang deposits are higher than the homogenization temperatures of the fluid inclusions in the ores, signifying that the organic matter maturation predated Au mineralization. No correlation between the organic matter contents and Au concentrations were recognized in the ores. However, the most striking observation is that there is a positive correlation between the S2 (a parameter of Rock-Eval analysis), Au and As contents of the ores in the Lannigou deposit. Organic matter maturation and migration is apparent from the TOC vs. HCI diagram. Furthermore, group analysis of the dichloromethane extractable organic component of the ores and host rocks shows that the maturation degree of the organic matter in the ores is slightly higher than that of the host rocks in the Lannigou gold deposit. However, the compositions of their alkanes, steranes and terpenes, which serve as biomarkers, are quite similar; this suggests that the organic matter found in the ores and host rocks has a common marine source. Organic matter probably contributed to the preconcentration of Au in the host rocks. Hydrocarbons in the system, on the other hand, clearly contributed to the emplacement of the gold mineralization through thermal sulfate reduction. Organic matter in the solution might have increased the potential of the hydrothermal solution to transport Au.

CHARACTERIZATION OF FINE-GRAINED TURBIDITE DEPOSITS FROM THE SOUTH CHINA SEA SEDIMENT CORES

Two depositional processes controlled the muddy sediments in the South China Sea Basin. Bathyal sediments depositional rate was 7.66 cm/la in the northern continental slope of the Basin where turbidity current was almost nonexistent. In the northern margin of the Basin, abyssal sediment depositional rate was 5.05cm/ka and turbidity current occurrence averaged 0.22 per 1000 years. Turbidite was found in the middle of the Basin. Over half of the muddy sediments in the deep sea basin were deposited by turbidity currents, and had typically graded bedding, and contents of organic matter, calcareous material and micropaleontologic species inconsistent with the environment.

Anthropogenic Effect on Deposition Dynamics of Lake Sediments Based on ^(137)Cs and ^(210)Pb_(ex) Techniques in Jiuzhaigou National Nature Reserve,China

Radionuclide dating techniques characterized by137Cs and210Pbex have recently been applied in the study of lake sediments around the world.In this study,a chronological series of sediment cores was established based on137Cs and210Pbex analyses along with the evaluation of sediment properties,such as particle size distribution,total organic carbon(TOC),carbonate content,and acid-insoluble residue,to study sediment accumulation rates,sediment sources,and responses to human activities in the Jiuzhaigou National Nature Reserve in southwestern China.In terms of the particle size distribution of sediments,silt content was the highest,and clay and sand contents were relatively low.The sediments displayed high TOC contents because of the significant amounts of vegetation grown in the lakes.The carbonate content was also high due to the overall geological background of carbonates in Jiuzhaigou.Carbonate content tended to decline from top to bottom in the sediment cores,whereas the acid-insoluble residue tended to increase.These results suggested that the depth variation of the environmental parameters of the sediments in two lakes in Jiuzhaigou would correspond to each other.The results indicated that the sediment rate of Jiuzhaigou was generally high with strong siltation,indicating that serious soil loss was induced by intensive human activities in the basin over the past decades.The increases in the mass accumulation rate,contents of acid-insoluble residue,and mean particle size during the periods of 1840–1900s,late 1930s–early 1950s,1966–1978,and2003–2006 revealed the occurrence of severe soil and water loss as a result of extensive agricultural expansion,large-scale deforestation,and road construction in Jiuzhaigou.The deposition rate and the properties of lacustrine sediments could reflect the significant impact of human activities on lake sedimentation during Jiuzhaigou′s history.

Hydrothermal Sedimentary Mineralization of the Super-large Bamianshan Fluorite Deposit in Zhejiang Province, China

The Bamianshan fluorite deposit is a super-large one recently discovered in Zhejiang Province of China. This paper presents an analysis of its geological background, orebody and ore characteristics, petrochemical characteristics of host rocks, rare earth elements （REE） of rocks and ores, fluid inclusions in fluorite and Sm-Nd isotopic features in an effort to study its sedimentary mineralization. The result shows that the super-large Bamianshan fluorite deposit is of hydrothermal sedimentation genesis, deformed by the later hydrothermal fluid. Integrated with host rocks and orebody characteristics, it is inferred that the deposit originates from the Cambrian sedimentary rocks. And the later magmatic activities deformed some orebodies in different degrees, forming steeply dipping vein orebodies in the tectonic belts regionally.