Yangtze River Drainage Research Articles

Speleothem evidence for temporal–spatial variation in the East Asian Summer Monsoon since the Medieval Warm Period

AbstractPublished annual‐to‐decadal‐resolution stalagmite δ18O records since AD 900 from six caves (Dongge, Furong, Heshang, Buddha, Shihua and Wanxiang) in China were analyzed to detect temporal and spatial variability of the East Asian Summer Monsoon strength, which strongly affects wet/dry conditions in eastern China. The empirical mode decomposition method was used to obtain trends of the six cave records. After the base trend was determined, δ18O anomalies of each record were computed by subtracting the base trend. Mean δ18O anomaly values of the detrended time series for each cave record were calculated for four periods: (i) Medieval Warm Period (MWP; AD 900–1250): (ii) Little Ice Age phase 1 (LIA‐1; AD 1250–1550); (iii) Little Ice Age phase 2 (LIA‐2; AD 1550–1850); and (iv) modern period (MD; AD 1850–2000). From these anomalies, the temporal and spatial variability of wet/dry conditions has been identified. Positive values of the mean δ18O anomalies indicating drier conditions appeared in the lower Yangtze River Drainage Area and Southeast Coast Area during MD‐1, LIA‐1 and MWP, whereas negative values existed in north, south and Yangtze areas of eastern China during LIA‐2. The results agree with the dryness/wetness index reconstructed by Chinese historic records in general. These results illustrate that wet and dry conditions in different regions of eastern China could be opposite under monsoon influence, so that no single speleothem δ18O record could represent the monsoonal climate in this vast region. Climatic patterns in the monsoonal region can be either a combination of warm/wet and cold/dry or a combination of cold/wet and warm/dry on annual‐to‐centennial scales. A 128‐year periodic cycle exists in all six cave records, whereas 64‐year (possibly a harmonic of 128‐year periodicity) and 42‐year periodicities appear in Shihua, Heshang and Dongge records. These cycles may reflect the influence of solar activity on the East Asian Summer Monsoon. Copyright © 2012 John Wiley & Sons, Ltd.

Holocene Flooding History in the Yangtze River Drainage as Recorded by Subaqueous Delta Sediments

Holocene Flooding History in the Yangtze River Drainage as Recorded by Subaqueous Delta Sediments

Nitrogen budget in the Changjiang River drainage area

We established a budget model of nitrogen (N) inputs and outputs between watersheds and waterbodies to determine the sources of riverine N in the Changjiang (Yangtze) River drainage area. Nitrogen inputs in the budget included N from synthetic fertilizer, biological fixation by leguminous and other crops, wet/dry atmospheric deposition, excreta from humans and animals, and crop residues. The total N input was estimated to be 17.6 Tg, of which 20% or 3.5 Tg N was transported into waterbodies. Of the total N transported into waterbodies, the largest proportion was N from animal waste (26%), followed by N from atmospheric wet/dry deposition (25%), synthetic fertilizer N (17%), N in sewage wastes (17%), N in human waste from rural areas (6%) and industrial wastewater N (9%). We studied the spatial patterns of N inputs and outputs by dividing the Changjiang River drainage area into four sub-basins, from upstream to downstream: the Tongtian River drainage area (TTD, the headwater drainage area, 138 000 km2, less disturbed by human activities); the Jinsha River drainage area (JSD, 347 000 km2, less disturbed by human activities, approx. 3 500 km upstream of the Changjiang estuary); the Pingshan-Yichang drainage area (PYD, 520 500 km2, large-scale human disturbance, about 2 000 km upstream of the Changjiang estuary); and the Yichang-Datong drainage area (YDD, 699 900 km2, large-scale human disturbance, approx. 620 km upstream of the Changjiang estuary). The average N input into waterbodies was 2.3, 7.3, 24.1, and 28.2 kg N/ha in the TTD, JSD, PYD, and YDD sub-basins, respectively, suggesting an increase of N-components of more than 10 times from upstream to downstream areas.

Occurrence of Bothriocephalus acheilognathi (Cestoda, Bothriocephallidea) in grass carp Ctenopharyngodon idella in the Changjiang River drainage

Bothriocephalus acheilognathi is a potentially serious pathogen in wild or cultured fish in worldwide distribution. We examined 58-farmed grass carp from Nanchang in the Changjiang (Yangtze) River drainage, from which 20.7% were found to harbor the parasite with an infection intensity of 36.9 +/- 54.7. The parasites were identified based on morphology and rDNA ITS sequence analysis. The present report represents the first record of the parasite in grass carp Ctenopharyngodon idella in the river drainage.

Spatial controls on erosion in the Three Rivers Region, southeastern Tibet and southwestern China

Global data suggest that erosion rates variously scale with steepness or climate forcing (precipitation or glacial excavation), but the relative influence of these factors has proven difficult to assess without comparisons from a single location. A new suite of detrital 10Be data from the Three Rivers Region, SE Tibet is used to examine the relative importance of rainfall and relief in predicting patterns of erosion rates across a region with a strong gradient in exhumation. The data reveal millennial erosion rates vary by two orders of magnitude, from 0.01 to 8 mm/yr across a regional gradient in exhumation rates inferred from previous thermochronology and cosmogenic nuclide data to the west and east of the study region. The new millennial erosion rates mirror the pattern of decreasing exhumation rates from west to east across the region, with the highest rates in the lower Salween River drainage and the lowest rates in the Yangtze River drainage. Erosion rates in the Mekong and Salween River drainages are correlated with mean local relief whereas in the Yangtze River drainage they are correlated most strongly with mean annual rainfall. The tectonic setting of this region, with a strong west to east gradient in exhumation rates which we infer to mirror a gradient in rock uplift, seems to exert a stronger control on erosion rate patterns than rainfall or relief.

A 600-year flood history in the Yangtze River drainage: Comparison between a subaqueous delta and historical records

Based on grain size analysis and high-resolution elemental scanning of core YD0901, taken from the subaqueous Yangtze River delta, a 600-year flood history was reconstructed for the Yangtze River drainage system. Zr/Rb ratios were chosen as a proxy for Yangtze River floods. Zr resides mainly in the coarse-grained minerals, and Rb is found in the fine-grained minerals. When floods occur, the discharge of the Yangtze River increases, which carries more coarse-grained minerals into the East China Sea. Therefore, deposition of coarse-grained minerals significantly increases relative to fine-grained minerals on the subaqueous delta, and subsequently the Zr/Rb ratios also increase. The higher the Zr/Rb peaks, the greater number of coarse particles deposited by saltation processes. Zr/Rb peaks correlate very well with historical records for Yangtze River floods. Especially at about AD 1870, the Zr/Rb ratio reached a maximum value over the last 600 years, which is consistent with “the extreme flood event” in the upper and middle reaches of the Yangtze River in AD 1870, as indicated in the historical records. Results show that floods have occurred at a relatively high frequency over the last 600 years, which is consistent with historical records when, during the Ming-Qing Dynasty, floods occurred once every 4 years. In addition, spectral analysis of the Zr/Rb ratio showed that there is close link between the Yangtze River floods and ENSO intensity.

Type locality and identity of Acrossocheilus kreyenbergii (Regan, 1908), a senior synonym of Acrossocheilus cinctus (Lin, 1931) (Teleostei: Cyprinidae)

Although Acrossocheilus kreyenbergii has been treated as a valid species since its original description, the type locality and identity of this species have hitherto remained uncertain. It is shown in this study that its precise location of ‘Tinghsiang’ or ‘Pinghsiang,’ the type locality of Gymnostoma kreyenbergii Regan, is the present Pingxiang City, Jiangxi Province, in the Gan Jiang, a tributary flowing to the Boyang Lake system, or in the Yangtze River drainage. Observation of the type specimens of this species and further comparison with those of other barred congeners reveal that G. kreyenbergii is in fact a senior synonym of Barbus cinctus Lin.

Variations of East Asian summer monsoon since the last deglaciation based on Mg/Ca and oxygen isotope of planktic foraminifera in the northern East China Sea

[1] Variations in Mg/Ca-based sea surface temperature and oxygen isotope ratio (δ18O) of the surface water in the northern East China Sea (ECS) were reconstructed with high resolution during the last 18 kyr using planktic foraminifera. Millennial-scale variations between warmer, more saline surface water and cooler, less saline surface water were recognized during the early deglacial period and the Holocene, suggesting changes in the mixing ratio between the Kuroshio Water and the Changjiang Diluted Water. Stronger East Asian summer monsoon (EASM) precipitation events in south China are identified at 10.5, 8.8, 7.0, 5.3, 4.7, 2.9, 1.7, and 0.5 ka, based on sea surface salinity (SSS) records of the northern ECS. Weaker EASM precipitation events are also detected at 9.3, 8.3, 7.3, 6.0, 3.3, 2.3, 0.7, and 0.4 ka during the Holocene. These events agree with the maxima in δ18O records of stalagmites from various parts of the Changjiang (Yangtze) River drainage. This agreement supports that our SSS record properly captures the millennial-scale dry (less EASM precipitation) events over the drainage basin of the Changjiang River during the Holocene. These dry events are also in good agreement with North Atlantic ice-rafted events, suggesting a teleconnection between North Atlantic climate and the EASM during the Holocene.

Mosses Indicating Atmospheric Nitrogen Deposition and Sources in the Yangtze River Drainage Basin, China

Characterizing the level and sources of atmospheric N deposition in a large‐scale area is not easy when using physical monitoring. In this study, we attempted to use epilithic mosses (Haplocladium microphyllum (Hedw.)) as a bioindicator. A gradient of atmospheric N deposition from 13.8 kg N ha−1 yr−1 to 47.7 kg N ha−1 yr−1 was estimated on the basis of moss tissue N concentrations and the linear equation between them. The estimated results are reliable because the highest atmospheric N deposition occurred in the middle parts of the Yangtze River, where the highest TN concentrations were also observed. Moss δ15N values in cities and forests were found in distinctly different ranges of approximately −10‰ to −6‰ and approximately −2‰ to 2‰, respectively, indicating that the main N sources in most of these cities were excretory wastes and those in forests were soil emissions. A negative correlation between moss δ15N values and the ratios of NH4‐N/NO3‐N in deposition (y = −1.53 x + 1.78) has been established when the ratio increased from 1.6 to 6.5. On the basis of the source information, the negative moss δ15N values in this study strongly indicate that NHy‐N is the dominant N form in N deposition in the whole drainage basin. These findings are supported by the existing data of chemical composition of local N deposition.

Nd and Sr isotopic compositions of sediments from the Yellow and Yangtze Rivers: Implications for partitioning tectonic terranes and crust weathering of the Central and Southeast China

New Nd and Sr isotope data are presented in this paper for sediments from the Yellow and Yangtze River drainage basins. The average 143Nd/144Nd isotope compositions of fine-grained sediments from two drainage basins seem similar. The T DM Nd ages of sediments from the two drainage basins are relatively uniform but exhibit subtle differences. This reflects the different underlying bedrocks, in association with the unique tectonic terranes that comprise central and southeastern China, including the North China Block, the Yangtze Block, the South China Block, the Tibet Plateau and the Qinling-Dabie Orogenic Belt. In contrast, there is an obvious difference in the 87Sr/86Sr ratios between fine-grained sediments of the Yellow and Yangtze Rivers, which actually reflects an increase in chemical weathering intensity from northwestern to southeastern China.

Pseudobagrus brachyrhabdion, a new catfish (Teleostei: Bagridae) from the middle Yangtze River drainage, South China

Pseudobagrus brachyrhabdion sp. nov., from the Yuan Jiang and Xiang Jiang of the middle Yangtze River drainage in Hunan and Guizhou Provinces, South China, is described herein. It is distinguished from all other Pseudobagrus species with a truncate or slightly emarginated caudal fin by an unique combination of the following characters: supraoccipital plate and nuchal plate broadly interspaced and covered with skin; nasal barbels only at most reaching anterior margin of eye; maxillary barbels reaching slightly beyond posterior margin of eye; outer mandibular barbels extending to posterior margin of eye; dorsal fin with a somewhat convex distal margin, origin nearer to pectoral-fin insertion than to pelvic-fin insertion; dorsal-fin spine shorter than pectoral spine, with a somewhat serrated posterior margin; pectoral-fin spine with a smooth anterior margin; anal fin with 20-23 rays, base length 23.8-32.0% of standard length, posterior end of anal-fin base anterior to posterior end of adipose fin base; no longitudinal black band extending along flank; eyes large, diameter 16.3-23.7% of head length; and number of vertebrae 5 + 43-46.

Triplophysa lixianensis, a new nemacheiline loach species (Pisces: Balitoridae) from the upper Yangtze River drainage in Sichuan Province, South China

Triplophysa lixianensis, a new nemacheiline loach species, is described from the Min Jiang of the upper Yangtze River drainage in Sichuan Province, South China. It can be separated from all other species of Triplophysa by having a unique combination of the following characters: posterior chamber of gas bladder greatly reduced or absent; caudal peduncle columnar with a roughly round cross-section at its beginning; anterior edge of lower jaw completely exposed or uncovered by lower lip; intestine short, forming a zigzag loop below stomach; dorsal-fin origin closer to caudal-fin base than to snout tip; pelvic fin inserted anterior to dorsal-fin origin; snout length 50.6–57.5 % of head length; eye diameter 12.3– 15.4 % of head length; caudal peduncle length 25.1–27.1 % of standard length; anal fin with five branched rays; lower lip greatly furrowed with two thick lateral lobes; and body smooth or scaleless.

Fifteen novel polymorphic microsatellites in rock carp, Procypris rabaudi (Tchang), an endemic fish species in the upper reaches of the Yangtze River drainage

Fifteen new microsatellite markers were isolated in rock carp, Procypris rabaudi (Tchang), from an AC-enriched genomic library. The allele number of these loci ranged from three to 13 (average 6.87 per locus) in the tested 24 individuals. Polymorphism information content (PIC) ranged from 0.453 to 0.821 with an average of 0.719. Average observed and expected heterozygosities were 0.712 (range 0.565–0.917) and 0.772 (range 0.542–0.855), respectively. These microsatellite markers could be useful in the population genetic study of rock carp.

Strontium isotopic compositions of dissolved and suspended loads from the main channel of the Yangtze River

The concentrations of Sr and 87Sr/ 86Sr isotopic ratios have been measured in the dissolved loads from the main channel of the Yangtze River. The result shows that the Yangtze River mainstream water has considerably higher Sr concentration (202–330 μg kg −1) and slightly lower 87Sr/ 86Sr ratio (0.7098–0.7108) than the global average runoff values of dissolved Sr (78 μg kg −1) and 87Sr/ 86Sr ratio (0.7119). The 87Sr/ 86Sr values of 0.7098–0.7108 in river waters result from the intense weathering of carbonate and evaporate rocks that enriched in the Yangtze River drainage basin. The calculated result based on the end-member mixing model shows that about 91% of total dissolved Sr are derived from the weathering of carbonate and evaporate rocks and the other 9% derived from the weathering of silicate rock. The Yangtze River transports about 1.86 × 10 11 g yr −1 (2.12 × 10 9 mol yr −1) of dissolved Sr annually to the East China Sea, with an average 87Sr/ 86Sr of 0.7108. The calculated “ 87Sr excess flux” of the Yangtze River is about 2.12 × 10 7 mol yr −1, indicating the important impact on seawater Sr isotope evolution. The measured 87Sr/ 86Sr ratios of suspended particulate matters in the Yangtze River water ranging from 0.7178 to 0.7252, are about 0.015 higher than that of corresponding dissolved loads, reflecting more important contribution of silicate particles in suspended particulate matters and preferential dissolution of carbonate rocks during basin weathering.

Transport process of radionuclides in the East China Sea

Damming is a common anthropogenic intervention along the course of rivers, which is defined as "artificial-lake effect", both in China and across the world. Today as many as 48000 dams and/or reservoirs are in operation in the Changjiang River (Yangtze River) drainage area, and more are being constructed. While damming is well known to affect riverbome nutrient loads, and thus the riverine ecosystems owing to removal of carbon fixation, and removal of particles in reservoir sediments, there is limited information on the detailed early diagenesis of sediments in reservoirs including the regeneration processes of nutrients deposited in sediments and exchange flux across the sediment-water interface, which is important for mass balance of riverborne nutrients. In the present study, two large-size reservoirs, Wujiangdu Reservoir (WJDR) and Dongfeng Reservoir (DFR), located on the main steam of the Wujiang River and with uniformity hydrography and discrepancy biogeochemical activity (e. g. primary production), were selected for a comparative study on the detailed processes of nutrient regeneration. Water, pore water and sediment were sampled from these two reservoirs and dissolved organic carbon (DOC), NH4 +, NO3-, PO43", dissolved silica (DSi) in the overlying water and pore water, and total organic matter in sediments were determined. The results of correlation analysis suggested that in these two reservoirs, processes of nutrient regeneration near the sediment-water interface were significantly different. As a result of rapid decomposition of algae-derived "labile" organic matter in upper sediments, nutrient regeneration processes and upward fluxes in WJDR are dramatically stronger than those of DFR. NH4 + upward flux from sediment in WJDR was about 17 times higher than that in DFR. PO43 flux in WJDR is about 13 times above that in DFR. DOC flux in WJDR is larger that in DFR by 5 times, and DSi by 1 time. These results implied that, retention nutrients in the reservoirs might be partly compensated by nutrient regeneration near the sediment/water interface, and thus of significance in further investigation of the 'artificial-lake effect' on riverine nutrient transportation, and on the troigic structure of aquatic ecosystems.

An analysis on spatial field effect of domestic tourist flows in China

Based on the data of tourism sampling check from 1999 to 2003 in China, and in the context of spatial field effect,this psper uses factor analysis to show the basic character of domestic tourist flows origin, distribution, centralization, decentralization and their relativity of tourist flows spatial network. The results are as follows: (1) Economy is the main driving force of the tourist flows origin, the effect of cultural driving force is intensifying and tourist resource is the main driving force of the tourist distribution. Now, China has formed four tourist flows original fields and five tourist destinations. (2) Influenced by market principle, the hierarchical structure of tourist centralization fields and decentralization fields represents the spatial sequence model of K = 3. (3) The regional structure of tourist centralization fields show the character of U form, and the regional structure of tourist decentralization fields represent the pattern of third class ladder. (4) The spatial network indexes of β and γ indicate that the relativity of tourist flows spatial network is feebleness. Finally, the paper regards that China should expedite the tourism development of the zones three namely the two zones of the Yangtze and Yellow river drainage areas and the three regions of the south coastal provinces, the north coastal provinces and northeast provinces in China. They are the key directions to push energetically the cooperation among tourist regions, endeavor to construct the tourist spatial network system, adjust and optimize the directions and quantity of tourist flows, as well as the key factors to enhance the network level of tourist flows.

Exploring the mechanism of species endangerment and conservation strategy in the Yangtze River drainage

Exploring the mechanism of species endangerment and conservation strategy in the Yangtze River drainage

Ocean Pollution from Land-based Sources: East China Sea, China

The environment of East China Sea (ECS) has been faced by huge stresses from anthropogenic activities and population growth in the Yangtze River drainage basin and the areas along the coasts. Improper use of natural resources and short-term economic objectives have resulted in severe environmental degradation in a fairly short time frame and the degradation has now reached a level where the health and well being of the coastal populations are threatened. The main pollutants are inorganic nitrogen, phosphate, oil hydrocarbons, organic matters and heavy metals. Nutrients cause eutrophication of the coastal waters and the estuarine area and very often stimulate the occurrence of red tides. The environmental pollution of Yangtze River basin directly impact on the state of the marine environment in the ECS. The ecosystem stability is maintained by a steady water discharge from the river, that mixes with the marine salty water in the estuary, and the sediment loads from the river that balance ocean erosion in the delta and its adjacent coastal area. The large-scale water transfer and dam constructions in the Yangtze River basin will change this basis. For the ECS the challenge is to reverse the negative processes taking place and to restore ecosystem balance. The main challenge is to integrate socioeconomic and environmental decision making in order to promote sustainable development. A better understanding of the driving forces in society that cause these environmental pressures is required in order to overcome these obstacles. International cooperation may be an important contributor to the progress and in particular provide access to financial, technological, scientific and human resource assistance.

Dentiphilometra monopteri n. gen., n. sp. (Nematoda: Philometridae) from the abdominal cavity of the ricefield eel Monopterus albus in China.

A new genus and species of philometrid nematode Dentiphilometra monopteri n. gen., n. sp., are described on the basis of the specimens found in the abdominal cavity of the ricefield eel (swamp-eel) Monopterus albus (Zouiev) from Liangzi Lake (the Yangtze River drainage system), Hubei Province, in central China. Dentiphilometra, assigned to the Philometrinae, differs from other genera of this subfamily mainly in the presence of a sclerotized oral ring armed on its inner surface by numerous small peribuccal teeth in the gravid female. The new species is characterized by minute cephalic papillae, a greatly developed anterior esophageal bulb separated from the cylindrical part of the esophagus, anterior extention of the esophageal gland anterior to the nerve ring, and by large caudal projections in females and equal spicules 0.051-0.096 mm long in males. This is the second philometrid species recorded from fishes of the Synbranchiformes.

A Reassessment of the Distribution of Cuora flavomarginata Gray 1863 on Mainland China

The geographic distribution of Cuora flavomarginata Gray 1863 is poorly known, but an examination of the Chinese literature and museum records helps elucidate its historic range. According to these data, there are two clusters of localities, one on the eastern coast of China near and along the Fuchun and Yangtze River drainage and another in southern China along the Pearl River drainage. The localities in southern China are probably invalid due to the turtle trade. The best estimate of the historical distribution of C. flavomarginata is along the eastern Yangtze River and its associated tributaries as well as the Fuchun drainage. The identification of viable C. flavomarginata populations in these areas, if they still exist, is necessary for their conservation.