Recent sedimentary records in the East China Sea inner shelf and their response to environmental change and human activities

The East China Sea continental shelf is a unique area for the study of land-sea interactions and paleoenvironmental change because it receives a large amount of terrestrial material inputs. In recent decades, human activities and global climate change have greatly aff ected river discharges into the sea. However, changes in the deposition process caused by these factors in the East China Sea continental shelf are unclear. We collected eight short sediment cores from the East China Sea inner shelf(ECSIS) using a box core sampler in 2012 and 2015. The grainsize, 2 10 Pb, and 1 37 Cs of these cores were analyzed in order to reconstruct the deposition history since the 1950 s, and to reveal human activity and climate change influences on sediment deposition in the ECSIS. Results indicated that sediment grain size became finer after 1969, turned coarser after 1987, and then further coarser since 2003, corresponding well to the three steps of sediment load drop in the Changjiang(Yangtze) River, which are mainly caused by human activities(particularly the closure of the Three Gorges Dam). Simultaneously, the East Asian Monsoon influenced the deposition process in the ECSIS by changing the intensity of coastal currents. Mean grain size variations in the fine-grained population(divided by grain size vs. standard deviation method) coincided with that of the East Asian Winter Monsoon strength and reflected its weakness in 1987. Abrupt changes in sediment grain size over a short time scale in these sediment cores were generally caused by floods and typhoons. Spectral analyses of the sediment cores showed periodicities of 10–11 and 20–22 years, corresponding to the periodicity of solar activity(Schwabe cycle and Hale cycle). Mean grain size time series also displayed a 3–8 year periodicity corresponding to El Ni?o Southern Oscillation periodic change.     

Interpreting sedimentation dynamics at Longxi catchment in the Three Gorges Area,China, using Cs-137 activity,particle size and rainfall erosivity

Reservoir sedimentation dynamics were interpreted using Cs-137 activity,particle size and rainfall erosivity analysis in conjunction with sediment profile coring.Two sediment cores were retrieved from the Changshou reservoir of Chongqing,which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an acrylic tube with an inner diameter of 6 cm.The extracted cores were sectioned at 2 cm intervals.All sediment core samples were dried,sieved(2 mm) and weighed.137 Cs activity was measured by γ-ray spectrometry.The particle size of the core samples was measured using laser particlesize granulometry.Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends.The peak fallout of 137 Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B.The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982,1989,1998 and 2005,respectively.Sedimentation rates were calculated according to the sediment profile chronological controls of 1956,1963,1982,1989,1998 and 2005.The highest sedimentation rate was around 2.0 cm?a~(-1) between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented,leading to accelerated soil erosion in the Longxi catchment.Since 1990 s,andparticularly since 2005,sedimentation rates clearly decreased,since a number of soil conservation programs have been carried out in the catchment.The combined use of 137 Cs chronology,particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration.Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.     

Impact of Human Activities on Depositional Process of Tidal Flat in Quanzhou Bay of China

As a very important component of a coastal system,tidal flats come to be a focus of the studies on land-ocean interaction in the coastal zone because those areas are subjected to intense human activities and are highly sensitive to the global change.The Quanzhou Bay,located along the middle part of Fujian coast of China,covers about 136.4km2,and the area of coastal wetland in the entire bay from intertidal to subtidal with 6m of water depth accounts for 96% of the total area.Seven short cores were collected and divided in situ with the interval of 5cm on the coastal wetlands of Quanzhou Bay on April 19,2006.The sediment samples were scattered and the grain sizes were measured by using Mastersizer 2000.Human beings' activities on tidal flat have disturbed the vertical distribution of sediments in stratigraphic sequence and accelerated the sedimentation rates.Grain size analysis results show that the grain size diameters increase and sediment becomes worse sorted towards the sea under the strong human disturbance;Spartina alterniflora can play a role of trapping the fine sediment;but near the bank,the sediment becomes coarse and there are two peak values on frequency curve influenced by the sandpile.The trough formed by human activities along the coastline changes the transport path of water and suspended sediment.The sediments are transported through the trough and deposit in it during the flood;the ebb flow is retarded by the flow output through the adjacent trough,and the deposited sediment can not be re-suspended;then,the sedimentation rate increases.In situ observation show that the sedimentation rate is about 8-10cm/yr.     

Phosphorus speciation in wetland sediments of Zhujiang (Pearl) River Estuary, China

Phosphorus fractions and adsorption-release characteristics of sediments in the Zhujiang(Pearl) River estuary wetland were investigated.Results showed that the total phosphorus(TP) content in surface sediments ranged from 648.9 mg/kg to 1064.0 mg/kg;inorganic phosphorus(IP) was the major fraction of TP and ranged from 422.5 mg/kg to 643.9 mg/kg.Among the inorganic phosphorus,the main fractions were phosphorus bound to Al and Fe(Fe/Al-P),and calcium-bound phosphorus(Ca-P),accounting for 23%–42% and 21%–67% of IP,respectively.The vertical distribution of TP contents were significantly positive correlated with organic phosphorus(Org-P) and Fe/Al-P contents.The bio-available phosphorus contents in vertical sediments varied from 128.6 mg/kg to 442.9 mg/kg,mainly existed in Fe-Al/P fraction,and increased from the bottom to top sediments.The transport of phosphorus in sediment-water interface was controlled by the soil characteristics.The active Fe and Al content was considered as the main factor that determines adsorption capacity in vegetated marsh wetland.The P buffering capacity of the sediments in vegetated marsh wetland was greater than that in mudflat wetland.The potential risk of eutrophication in the study area is high.Reducing terrestrial phosphorus discharge and preventing the sediment Fe/Al-P release to the interstitial water are the possible solutions to reduce the risk of eutrophication in estuary wetlands,and planting vegetation in estuary wetland can also reduce the release of phosphorus in surface sediment.     

Reconstructing environmental changes of a coastal lagoon with coral reefs in southeastern Hainan Island

Coastal lagoons with small catchment basins are highly sensitive to natural processes and anthropogenic activities. To figure out the environmental changes of a coastal lagoon and its contribution to carbon burial, two sediment cores were collected in Xincun Lagoon, southeastern Hainan Island and (210) ~Pb activities, grain size parameters, total organic carbon(TOC), total nitrogen(TN), total inorganic carbon(TIC) and stable carbon isotopes(δ~(13)C) were measured. The results show that in 1770–1815, the decreasing water exchange capacity with outer open water, probably caused by the shifting and narrowing of the tidal inlet, not only diminished the currents and fined the sediments in the lagoon, but also reduced the organic matter of marine sources. From 1815 to 1950, the sedimentary environment of Xincun Lagoon was frequently influenced by storm events. These extreme events resulted in the high fluctuation of sediment grain size and sorting, as well as the great variation in contributions of terrestrial(higher plants, soils) and marine sources(phytoplankton, algae, seagrass). The extremely high content of TIC, compared to TOC before 1950 could be attributed to the large-scale coverage of coral reefs. However, with the boost of seawater aquaculture activities after 1970, the health growth of coral species was severely threatened, and corresponding production and inorganic carbon burial flux reduced. The apparent enhanced inorganic carbon burial rate after 1990 might result from the concomitant carbonate debris produced by seawater aquaculture. This result is important for local government long-term coastal management and environmental planning.     

Chronology and nutrients change in recent sediment of Taihu Lake,lower Changjiang River Basin,east China

Two short sediment cores named ZS and THS dated by the 210Pb or 137Cs method were collected from the northwest and southwest of Taihu Lake respectivly,and total organic carbon(TOC) and nutrients including total nitrogen(TN) and total phosphorus(TP) were determined to analyze the chronology and nutrients change in recent sediment.The results show that 137Cs activities are low(less than 15 Bq/kg) in the two cores,attributed to the 137Cs migration.Based on 210Pb constant rate of supply(CRS) model,the sedimentation accumulation rates range from 0.13 g/(cm2·yr) to 0.76 g/(cm2·yr) in the ZS core,and from 0.10 g/(cm2·yr) to 0.56 g/(cm2·yr) in the THS core.A remarkable increase in organic matter and nutrients has occurred in the two dated cores since the mid-1980s.The historical changes of organic matter and nutrients in the two cores are consisitent with the monitoring data for surface sediment after the 1960s.The TP accumulation rates after the early 1980s are 0.97 and 0.92 times higher than those from the 1950s to the 1980s in ZS and THS cores,respectively.Higher TP concentrations in the past two-decade deposits of Taihu Lake are due to both diagenetic factors and human activities.     

Assessment of heavy metals in sediment in a heavily polluted urban river in the Chaohu Basin,China

The Nanfei River(Anhui Province,China) is a severely polluted urban river that flows into Chaohu Lake.In the present study,sediments were collected from the river and analyzed for their heavy metal contents.Multivariate statistics and the fuzzy comprehensive assessment method were used to determine the sources of pollution,the current pollution status,and spatial and temporal variations in heavy metal pollution in sediments.The concentrations of arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),nickel(Ni),lead(Pb),and zinc(Zn) in sediments ranged from 5.67–113,0.08–40.2,41.6–524,15.5–460,0.03–4.84,13.5–180,18.8–250,and 47.9–1 996 mg/kg,and the average concentrations of each metal were 1.7,38.7,1.8,5.5,18.8,1.3,2.5,and 11.1 times greater than the background values,respectively.Multivariate statistical analysis demonstrated that Hg,Cu,Cr,Cd,and Ni may have originated from industrial activities,whereas As and Pb came from agricultural activities.The fuzzy comprehensive assessment method,based on the fuzzy mathematics theory,was used to obtain a detailed assessment of the sediment quality in the Nanfei River watershed.The results indicated that the pollution was moderate in the downstream tributaries of the Nianbu and Dianbu Rivers,but was severe in the main channel of the Nanfei River and in the upstream tributaries of the Sili and Banqiao Rivers.Therefore,sediments in the Nanfei River watershed are heavily polluted and urgent measures should be taken to remedy the status.     

Grain-size related nitrogen distribution in southern Yellow Sea surface sediments

Forty-eight surface sediments of the southern Yellow Sea are separated into three grain-size fractions. Four forms of extractable nitrogen (nitrogen in ion-exchangeable form (Nie), nitrogen in weak-acid extractable form (Nwa), nitrogen in strong-alkali extractable form (Nsa) and nitrogen in strong-oxidant form (N50))are obtained by the sequential extraction. The results show that the contents and the distributions of the extractable nitrogen in the southern Yellow Sea surface sediments are closely related to sediment grain size. The distributions ofNie, Nso and total nitrogen (TN) present positive correlations with fine particles content, while Nwa and Nsa does not have such correlation. The net contents of all the forms of nitrogen increase with sediment grain size finer.     

Linking Monsoon Activity with River-Derived Sediments Deposition in the Northern South China Sea

The history of the East Asian monsoon(EAM) since Last Glacial Maximum is reconstructed based on records in a sediment core retrieved from the northern South China Sea. The provenance of organic carbon and the EAM's evolution are investigated using combined organic carbon, grain size, and AMS 14 C dating analysis. Responding to the strong winter monsoon, the marine organic matter was dominated in the sediments, and δ13 C of organic matter was high during the last glacial period. During the Holocene, the primary productivity decreased and the dilution effect of riverine inorganic clastics strengthened. Accordingly, the total organic carbon contents and δ13 C values decreased, and terrestrial organic matter content increased in the core sediments. The 4 μm grain size fraction, as the environmental sensitive grain size component, is determined to reconstruct the paleoclimatic records. During the last glacial period, the contents of 4 μm grain size component were mainly controlled by the sea level changes. Upon the Holocene, the influence of the sea level changes weakened and the roles of current system and provenance strengthened. The correlation between the EAM and solar insolation forcing is also discussed in this paper.     

Sediment transport in the Luanhe River delta: grain size trend analysis

Sediment grain size in the deltaic environment of the Luanhe River(LR), Liaoning, China,contains sediment transport pathway information useful in elucidating the shoreline change and fluvialmarine interaction. In this study, we utilized numerical partitioning of the sedimentary components and geostatistical grain size trend analysis(GSTA) to define the sediment transport pattern in the Luanhe River delta(LRD) and interpolated the sediment transport pattern using content changes of end numbers(EM).EM1(the mean grain size 7.12 Φ, fine silt), EM2(2.37 Φ, fine sand), and EM3(1.27 Φ, medium sand)components were identified by the numerical partitioning by GSTA. Kriging interpolation method was used to interpolate the parameters of the grain size for the regular grid, and the interpolation radius was 0.015 decimal degree. We chose 0.09 decimal degree as the characteristic distance for GSTA in the semivariogram model using the geostatistical method. The FB(-) case(finer, better sorted and more negatively skewed) was adopted in GSTA for its satisfaction in the Global Moran's I test. The result of the GSTA shows that the sediments in the south barriers(SBs) were transported to the southwest of the study area. The sediments in the north, in the SE direction of sediment transport trend from the river mouth, indicated that the sediments in the north of the study area were transported from the LR to the northern beaches, and to the south and east of the study area. The sediment transport trend that simplified by GSTA as the FB(-) case was approved by the content changes of sedimentary components(i.e. EM1, EM2, and EM3). In addition, the turbulent jet diffusion pattern indicated that the coarse sediments(EM3) were delivered by LR during the flood season, and the EM2 and EM1 were from wave and tide, respectively.     

Distribution and accumulation characteristics of heavy metals in sediments in southern sea area of Huludao City, China

The southern sea area of the Huludao City, Liaoning Province might be polluted by heavy metals because it is close to the Jinzhou Bay, one of the heaviest sea area polluted by heavy metals in China. The undisturbed modern sediment core can be used to analyze the accumulation and source of the pollutants using 137 Cs and 210 Pb ex . Thirty-five samples of surface sediment and two core sediments were collected from the southern sea area of Huludao City. The concentrations of copper (Cu), lead (Pb), chrome (Cr), zinc (Zn), arsenic (As) and mercury (Hg) in the surface sediments as well as Cu, Pb, Zn, Cr, 137 Cs and 210 Pb ex in the core sediments were determined to research the spatial distribution and accumulation characteristics, and to analyze the sources and the potential risks of heavy metals. The results show that the pollution levels of Zn and Hg are serious, and 26 stations are at moderate or heavy ecological risks. The concentrations of the heavy metals increase from east to west, as well as from open sea to offshore marine area. The concentrations of heavy metals are not high in the sediments adjacent to the Jinzhou Bay, and the influence caused by the seawater exchange with the Jinzhou Bay is little. The concentrations of the heavy metals in the core sediments show low-high-low characteristic, and it coincides with the pollution history of Huludao City. The atmospheric deposition of heavy metals from the Huludao Zinc Plant is likely to be the main source of pollution without direct discharge of wastewater. The high concentrations of heavy metals appear on the upper sediment of 20 cm. The shallow sediment with high heavy metal contents might be exposed to surface when it was disturbed by the ocean engineering and big storm surge, then cause risk to the safety of aquaculture and human healthy.     

137Cs and 210Pbex as soil erosion tracers in the hilly Sichuan Basin and the Three Gorges area of China

Accelerated soil erosion and land degradation represent major environmental problems for agricultural lands.Reliable information on the rates of soil loss is urgently needed.The traditional techniques for documenting rates of soil loss may meet this need,but face many limitations.The fallout radionuclides,especially 137 Cs and 210 Pb ex,are increasingly used as effective tracers to quantify soil erosion rates,and they represent a valuable complement to the existing classical methods.This paper aims to introduce the basis for assessing soil erosion rates on cultivated and uncultivated slopes by using 137 Cs and 210 Pb ex measurements,to compare the 137 Cs and 210 Pb ex reference inventories,and to report several case studies undertaken in the hilly area of Sichuan Basin and the Three Gorges area of China.     

Responses of primary productivity to current and climate changes in the mud area to the southwest of Cheju Island during the past 800 years

The biogenic silica (BSi), total organic carbon (TOC), total nitrogen (TN) and grain size were analyzed with a gravity core (3250-6) collected from the mud area in the north East China Sea. The average deposition rate of the upper core was about 0.078 cm yr^?1 based on the results of ²¹⁰Pb_ex. The mean grain size increased with depth in general. The frequency distribution of grain size showed that two marked changes of deposition environment occurred at 30 cm and 50 cm depths (about 1550 AD and 1300 AD, respectively). The variations of BSi and TOC indicated two distinct major periods of primary productivity over the past 800 years: a stage of low primary productivity corresponding to weak upwelling and low nutrient input below 30 cm depth (about 1200–1550 AD), and a stage of high primary productivity with strong currents and upwelling above 30 cm depth (about 1550–1950 AD). The stage with high primary productive appeared to be due to the northward-expanded muddy area caused by strong Asian Winter Monsoon and enhanced Yellow Sea Warm Current in winter. In conclusion, the BSi and TOC in the muddy sediments, the symbols of marine primary productivity, can be then used to investigate the evolution history of currents and relative climate change in the offshore areas.     

A 3600 years paleoclimatic change inferred from organic δ13C and TOC/TN of the Gucheng Lake sediments, southeast China

A 6.2 m thick core of Gucheng Lake sediment provided a 3600 years record of climate change. The contents of the TOC in the core changed from 2.63% to 8.48%, and the δ¹³C values of organic matter were from −21.54% to −27.3%. The TOC/TN ratios indicated that the organic materials in sediments were from lake plankton and land-derived plants. The 2.9–22 m core interval with high TOC/TN ratios, low δ¹³C values and low contents of TOC indicated a cold climate stage. The 6.2–5.5 m and 0.4–0.1 m intervals were characterized by low TOC/TN ratios, high δ¹³C values and high contents of TOC, and reflected temperate climate stages. Project 49372129 supported by NSFC.     

<Superscript>137</Superscript>Cs tracing dynamics of soil erosion,organic carbon,and total nitrogen in terraced fields and forestland in the Middle Mountains of Nepal

The Middle Mountains is one of the regions of Nepal most vulnerable to water erosion, where fragile geology, steep topography, anomalous climatic conditions, and intensive human activity have resulted in serious soil erosion and enhanced land degradation. Based on the ¹³⁷Cs tracing method, spatial variations in soil erosion, organic carbon, and total nitrogen (TN) in terraced fields lacking field banks and forestland were determined. Soil samples were collected at approximately 5 m and 20 m intervals along terraced field series and forestland transects respectively. Mean 137Cs inventories of the four soil cores from the reference site was estimated at 574.33 ± 126.22 Bq m^-2 (1 Bq (i.e., one Becquerel) is equal to 1 disintegration per second (1 dps)). For each terrace, the ¹³⁷Cs inventory generally increased from upper to lower slope positions, accompanied by a decrease in the soil erosion rate. Along the entire terraced toposequence, ¹³⁷Cs data showed that abrupt changes in soil erosion rates could occur between the lower part of the upper terrace and the upper part of the immediate terrace within a small distance. This result indicated that tillage erosion is also a dominant erosion type in the sloping farmland of this area. At the same time, we observed a fluctuant decrease in soil erosion rates for the whole terraced toposequence as well as a net deposition at the toe terrace. Although steep terraces (lacking banks and hedgerows) to some extent could act to limit soil sediment accumulation in catchments, soil erosion in the terraced field was determined to be serious. For forestland, with the exception of serious soil erosion that had taken place at the top of slopes due to concentrated flows from a country road situated above the forestland site, spatial variation in soil erosion was similar to the “standard” water erosion model. Soil organic carbon (SOC) and TN inventories showed similar spatial patterns to the ¹³⁷Cs inventory for both toposequences investigated. However, due to the different dominant erosion processes between the two, we found similar patterns between the <0.002 mm soil particle size fraction (clay sized) and ¹³⁷Cs inventories in terraced fields, while different patterns could be found between ¹³⁷Cs inventories and the <0.002 mm soil particle size fraction in the forestland site. Such results confirm that ¹³⁷Cs can successfully trace soil erosion, SOC and soil nitrogen dynamics in steep terraced fields and forestland in the Middle Mountains of Nepal.     

Features of soil redistribution and major element migration in a karst hillslope of Southwest China

In this study, we investigated the spatial characteristics of the rate of soil distribution and the mechanism of major element migration in a typical karst hillslope in Guangxi Province, Southwestern China. Soil redistribution was examined using ¹³⁷Cs technique under different hillslope components. With the combination of geochemical methods, the migration characteristics of major elements in soils of three hillslope components in both the horizontal and vertical directions were determined. Thirty-seven soil samples were collected and analyzed for ¹³⁷Cs and the major elements were determined. By using the profile distribution model the mean soil redistribution rates were found to be -17.01, 0.40 and -23.30 t ha^-1 yr^-1 in the summit (BYSD), shoulder (BYSY) and toeslope (BYSJ) components of the studied hillslope, respectively. In comparison to BYSD, the sesquioxides of Fe₂O₃ and TiO₂ tend to be enriched, whereas the alkalis (CaO, MgO, Na₂O and K₂O) tend to be depleted, both in the shoulder and toeslope components. Due to human and animal activities, the contents of CaO, MgO, K2O and Na₂O have somewhat increased within the topsoil. The results indicated that ¹³⁷Cs activities are significantly correlated with clay particles and organic matter, and are affected by the pedogenic process and vegatation. Overall, it maybe necessary to use techniques such as ¹³⁷Cs to investigate soil erosion with the combination of geochemical methods.     

Investigations of natural and artificial radioactive isotopes in seawater and sediments in the Yellow Sea and adjacent southeast area

Investigations of natural and artificial radioisotopes including 90Sr,137Cs, gross B and U carried out in the Yellow Sea and adjacent southeast area in 1963. 1964, 1975 and 1978 showed that radioactive pollution by 90Sr and 137Cs from atmospheric fallout had gradually decreased with time due to the cessation of atmospheric nuclear weapons tests in the 70s. The distributions of natural and artificial radioactive isotopes (U, Ra, Th. 40K and 137Cs) in sediments southwest of Jizhou Island were uniform. The more uniform may be related to the soluble species of U[Uo2(CO3)4] in the seawater.The high value of Th at stations 3 and 6 was related to the sandy clay sediment; the low value at station 8 was related to sandy sediment. The content of 137Cs in the eddy area being less than about half of that in the China inshore area showed that the source of Cs may be insufficient orthat the conditions for enriching " Cs in the circulation eddy area were not favorable.     

Using 137Cs tracing methods to estimate soil redistribution rates and to construct a sediment budget for a small agricultural catchment in the three gorges reservoir region, China

Soil erosion and associated off-site sedimentation are threatening the sustainable use of the Three Gorges Dam.To initiate management intervention to reduce sediment yields,there is an increasing need for reliable information on soil erosion in the Three Gorges Reservoir Region(TGRR).The purpose of this study is to use 137 Cs tracing methods to construct a sediment budget for a small agricultural catchment in the TGRR.Cores were taken from a pond and from paddy fields,for 137 Cs measurements.The results show that the average sedimentation rate in the pond since 1963 is 1.50 g cm-2 yr-1 and the corresponding amount of sediment deposited is 1,553 t.The surface erosion rate for the sloping cultivated lands and the sedimentation rate in the paddy fields were estimated to be 3,770 t km-2 yr-1 and 2,600 t km-2 yr-1,respectively.Based on the estimated erosion and deposition rates,and the area of each unit,the post 1970 sediment budget for the catchment has been constructed.A sediment delivery ratio of 0.5 has been estimated for the past 42 years.The data indicate that the sloping cultivated lands are the primary sediment source areas,and that the paddy fields are deposition zones.The typical land use pattern(with the upper parts characterized by sloping cultivated land and the lower parts by paddy fields) plays an important role in reducing sediment yield from agricultural catchments in the TGRR.A 137 Cs profile for the sediment deposited in a pond is shown to provide an effective means of estimating the land surface erosion rate in the upstream catchment.     

137Cs finger printing technique for erosion and sedimentation studies

137 Cs is an artificial radionuclide with a half-life of 30.2 years,which was released into the environment as a byproduct of atmospheric testing of nuclear weapons during the period of 1950s to 1970s with a peak deposition in 1963.137 Cs fallout was strongly and rapidly adsorbed by soil particles when it deposited on the ground mostly with precipitation.Its following movements will associate with the adsorbed particles.137 Cs tracing technique has been widely used in soil erosion and sedimentation studies since 1980s.This paper introduces the basis of the technique and shows several case studies of assessment of soil erosion rates,investigation of sediment sources and dating of reservoir deposits by using the technique in the Loess Plateau and the Upper Yangtze River Basin.