Wang, Jie; Liu, Guijian; Lu, Lanlan; Liu, Houqi
This study presents the total concentrations and chemical fractionations of metals (Cu, Pb, Zn, Ni, Fe, and Mn) in 54 surface sediment samples collected from the Huaihe River (Anhui Province) in eastern China. Compared with the average shale values, Zn and Pb exhibited the most substantial anthropogenic enrichment, especially in Fengtai and Huainan areas, the main industrial districts along the Huaihe River (Anhui Province). Low levels of Cu and Ni were observed in the sediments. Based on risk assessment code (RAC), the metals associated with weak acid soluble (F1) in the Huaihe River sediments followed the order: Mn > Zn > Cu > Pb > Ni > Fe. Manganese presented the most potential for releasing into the aqueous environment and can easily enter the food chain. Copper, zinc, nickel, and iron were found dominant in the residual fraction, implying that these four metals were strongly bound to the sediments. Lead showed a different partitioning pattern from that of other metals studied, with a large percentage in Fe-Mn oxide fraction, indicating that slight redox potential changes may make significant influence on the removability of Pb. Moreover, Cu in oxidizable (F3) and residual (F4) fractions presented high positive correlation with organic matter, which can explain the high percentage of Cu in these two fractions. PMID:26627208
Zhao, Junfang; Xu, Jingwen; Xie, Xingmei; Lu, Houquan
Drought assessment is important for developing measures to reduce agricultural vulnerability and thereby secure the livelihoods of those who depend on agriculture. This study uses four global ensemble weather prediction systems: the China Meteorological Administration (CMA), the European Centre for Medium-Range Weather Forecasts (ECMWF), the UK Met Office (UKMO), and the US National Centres for Environmental Prediction (NCEP) in the THORPEX (The Observing System Research and Predictability Experiment) Interactive Grand Global Ensemble (TIGGE) archive from 2006 to 2010. Based on results from the XXT (the first X denotes Xinanjiang, the second X denotes hybrid, and the T denotes TOPMODEL) distributed hydrological model, as well as soil moisture observations and digital elevation model (DEM) data, synthesized drought grades were established in the Huaihe River Basin of China. To filter out the impact of short-term fluctuations on observed soil moisture, a 30-day moving average was calculated. Use of the moving average significantly improves the correlation between observed soil moisture and simulated soil water deficit depth. Finally, a linear regression model describing the relationship between observed soil moisture and simulated soil water deficit depth was constructed. The deterministic regression coefficient was 0.5872, the correlation coefficient was 0.77, and the regression coefficient was -154.23. The trends in drought grades calculated using soil moisture and soil water deficit depth were found to be the same, and the grades agreed to within one level. Our findings highlight the importance of synthesizing drought grading when assessing drought using different soil moisture indicators in order to obtain a more comprehensive forecast of drought conditions. PMID:26930309
Zhang, Wang-shou; Su, Jing-jun; Du, Xin-zhong; Li, Xu-yong
Social economy in Huaihe River Basin had undergone enormous changes during 1990-2010. The grain yield had increased by 58%, from 64.14 million tons to 101.21 million tons, and the urbanization rate had increased by 22%, from 13% to 35%. Assessing the negative impacts of these high intensive human activities caused by rapid social development on terrestrial ecosystem would serve as a scientific basis for quantitative management of regional ecology. This paper estimated the spatial and temporal distribution of net anthropogenic nitrogen input (NANI) in Huaihe River Basin during 1990-2010. The results showed that there was an increasing trend in NANI in the period of 1990-2001, and after that this trend was slower. The NANI increased from approximately 17232 kg N · km(-2) · a(-1) in 1990 to a peak of 28771 kg N · km(-2) · a(-1) in 2003, and then declined to 26415 kg N · km(-2) · a(-1) in 2010. Chemical fertilizer and atmospheric deposition were the largest two sources of NANI, followed by food & feed import and biological nitrogen. Contributions from both chemical fertilizer and atmospheric deposition had been increasing continuously, respectively from 64% and 16% in 1990 to 77% and 19%. Our findings implied that the shift from fertilizer-supported agriculture and fossil fuel-supported industry to sci-tech lead economic development is urgently needed. PMID:26572039
Zong, Peishu; Wang, Huijun
This study evaluates the ability of the Abdus Salam International Center for Theoretical Physics (ICTP) version 3 Regional Climate Model (RegCM3) in simulating the summer rainfall amount and distribution and large-scale circulation over the Huaihe River basin of China. We conducted the simulation for the period of 1982-2001 and the wet year of 2003 to test the ensemble simulation capacity of RegCM3. First, by comparing the simulated rainfall amount and distribution against the observations, it is found that RegCM3 can reproduce the rainfall pattern and its annual variations. In addition, the simulated spatial patterns of 850-hPa wind and specific humidity fields are close to the observations, although the wind speed and humidity values are larger. Finally, the ensemble simulation of RegCM3 for summer 2003 failed to capture the spatial distribution and underestimated the magnitude of the precipitation anomalies, and the reasons are analyzed.
Dou, Ming; Zhang, Yan; Li, Guiqiu
Based on the monitoring data of 78 monitoring stations from 2003 to 2012, five key water quality indexes (biochemical oxygen demand: BOD5, permanganate index: CODMn, dissolved oxygen: DO, ammonium nitrogen: NH3-N, and total phosphorus: TP) were selected to analyze their temporal and spatial characteristics in the highly disturbed Huaihe River Basin via Mann-Kendall trend analysis and boxplot analysis. The temporal and spatial variations of water pollutant concentrations in the Huaihe River Basin were investigated and analyzed to provide a scientific basis for water pollution control, water environment protection, and ecological restoration. The results indicated that the Yinghe River, Quanhe River, Honghe River, Guohe River, and Baohe River were the most seriously polluted rivers, followed by Hongze Lake, Luoma Lake, Yishuhe River, and Nansi Lake. BOD5, CODMn, and NH3-N were the major pollution indexes, for which the monitoring stations reported that more than 40 % of the water quality concentrations exceeded the class IV level. There were 21, 50, 36, and 21 monitoring stations that recorded significantly decreasing trends for BOD5, CODMn, NH3-N, and TP, respectively, and 39 monitoring stations showed a significantly increasing trend for DO. Moreover, the water quality concentrations had a certain concentricity and volatility according to boxplot analysis for the 20 monitoring stations. The majority of monitoring stations recorded a large fluctuation for the monitoring indexes in 2003 and 2004, which indicated that the water quality concentrations were unstable. According to the seasonal variations of the water quality concentrations in the mainstream of Huaihe River, the monthly variation trends of the BOD5, CODMn, DO, NH3-N, and TP concentrations were basically consistent among the seven monitoring stations. The BOD5, CODMn, NH3-N, and TP concentrations were affected by the change of the stream discharge; changes in DO and NH3-N concentrations were influenced by
Yu, M.; Li, Q.; Lu, G.; Wang, H.; Li, P.
Accurate and reliable drought monitoring is of primary importance for drought mitigation and reduction of social-ecological vulnerability. The aim of the paper was to propose a short-term/long-term composited drought index (CDI) which could be widely used for drought monitoring and early warning in China. In the study, the upper Huaihe River basin above the Xixian gauge station, which has been hit by severe droughts frequently in recent decades, was selected as the case study site. The short-term CDI was developed by the Principle Component Analysis of the self-calibrating Palmer Drought Severity Index (sc-PDSI), the 1- and 3-month Standardized Precipitation Evapotranspiration Index (SPEI), Z Index (ZIND), the Soil Moisture Index (SMI) with the long-term CDI being formulated by use of the self-calibrating Palmer Hydrology Drought Index (sc-PHDI), the 6-, 12-, 18- and 24-month SPEI, the Standardized Streamflow Index (SSI), the SMI. The sc-PDSI, the PHDI, the ZIND, the SPEI on a monthly time scale were calculated based on the monthly air temperature and precipitation, and the monthly SMI and SSI were computed based on the simulated soil moisture and runoff by the distributed Xinanjiang model. The thresholds of the short-term/long-term CDI were determined according to frequency statistics of different drought indices. Finally, the feasibility of the two CDIs was investigated against the scPDSI, the SPEI and the historical drought records. The results revealed that the short-term/long-term CDI could capture the onset, severity, persistence of drought events very well with the former being better at identifying the dynamic evolution of drought condition while the latter better at judging the changing trend of drought over a long time period.
yao, xiuping; ma, jiali
Using ERA-Interim wind data and China's 756 meteorological station daily precipitation data, the shear line days, torrential rain days and shear line torrential rain days during June-July over Yangtze-Huaihe river region in 1981-2013 have been selected by 3 criteria, meridional shear of zonal wind, relative vorticity , zero line of zonal wind. It is shown that during June and July(61days) from 1981 to 2013,30.2 days (nearly 1 month) are torrential rain days, 33.2 days are shear line days,22.0 days are shear line torrential rain days. Shear line torrential rain days has accounted for nearly 2/3 of shear line days and nearly 3/4 of torrential rain days. The numbers of the shear line days, torrential rain days during June-July are on insignificant annual increase, the increase rate of which is one order of magnitude larger than that of shear line torrential rain days, which is basically unchanged in the past 33 years. Earlier than 2000, there are more frequency fluctuations of shear line day, torrential rain day and shear line torrential rain day compared with that later than 2000.There are some similar decadal variances in torrential rain days,shear line days and shear line torrential rain days over Yangtze-Huaihe river region,and those decadal variances of the 3 series are also similar with the decadal variance of precipitation amount over Yangtze-Huaihe river region in the period of 1981-2007.Shear line torrential rain mostly occur between late June and early July, the Meiyu period. The number of shear line torrential rain days during June-July shows 2-3 year period prior to 1995 and no significant period later than 1995.Climatologically, the numbers of shear line torrential day show 2-4 day period in early-middle June and middle-late July, while it shows no significant period from late June to early July, indicating that shear line torrential rain day maintain a stable frequency during that period ,and precipitation caused by shear line makes up most of the Meiyu
Zhang, Xiaolei; Song, Yuqin
Wetland restoration in floodplains is an ecological solution that can address basin-wide flooding issues and minimize flooding and damages to riverine and downstream areas. High population densities, large economic outputs, and heavy reliance on water resources make flood retention and management pressing issues in China. To balance flood control and sustainable development economically, socially, and politically, flood retention areas have been established to increase watershed flood storage capacities and enhance the public welfare for the populace living in the areas. However, conflicts between flood storage functions and human habitation appear irreconcilable. We developed a site-specific methodology for identifying potential sites and functional zones for wetland restoration in a flood retention area in middle and eastern China, optimizing the spatial distribution and functional zones to maximize flood control and human and regional development. This methodology was applied to Mengwa, one of 21 flood retention areas in China's Huaihe River Basin, using nine scenarios that reflected different flood, climatic, and hydraulic conditions. The results demonstrated improved flood retention and ecological functions, as well as increased economic benefits.
Zhang, Lei; Qin, Xiaoguang; Liu, Jiaqi; Sun, Chunqing; Mu, Yan; Gao, Jinliang; Guo, Wenfeng; An, Shikai; Lu, Chunhui
The sediments of the Huaibei Plain in semi-humid mid-eastern China represent valuable geological records with respect to eolian-fluvial interactions, depositional environments, and climate change in this region. Provenance and weathering conditions are often reconstructed using sedimentary geochemistry methods. In this study, an 8-m core from Huainan and a set of loess samples from northern and southern China were analyzed for major, trace, and rare earth elements (REEs). Results were compared to determine the samples' provenance. The major, trace, rare earth elements contents, and grain size distribution were found to fluctuate widely in the 2-8 m section of the Huainan core and more narrowly closer to the surface (0-2 m). This suggests a provenance shift at a depth of 2 m. The TiO2/Al2O3, SiO2/Al2O3, Th/Nb, La/Nb values and REE patterns in the upper core (0-2 m) are similar to those found in samples from the Chinese Loess Plateau (CLP). These results suggest that the CLP in northern China is likely to be the primary origin of the upper part (0-2 m) of the Huainan core. Compared with CLP samples, the upper part of the Huainan core exhibits lower K2O/Al2O3 values and higher chemical alteration indices. This is indicative of the material's substantial weathering during transportation and re-deposition and implies that these sediments could reasonably be classified as typical recycled loess. The sediments may have been transported from the CLP to Huainan as Yellow River flood events, probably during the last deglaciation (∼13.2 ka) as a result of increased precipitation, along with glacier and snow melt in the upper reaches of the Yellow River catchment during this period. This suggests that the Yellow River may have migrated into the Huaihe River catchment much earlier than the earliest historical records (361 BCE) suggest. The implications of this would be profound with respect to Chinese history.
Luo, Dan; Pu, Yabing; Tian, Haoyuan; Cheng, Juan; Zhou, Tingting; Tao, Yun; Yuan, Jing; Sun, Xin; Mei, Surong
Organochlorine pesticides (OCPs), one of the persistent organic pollutants (POPs) with highly lipophilic properties, long half-lives, and persistence in the environment, are prevalent in the environment even though they have been banned for >30years. We aimed to investigate the current OCP exposure levels in cord blood from healthy pregnant women residing in the Huaihe River Basin, China, and examined the association between OCP levels and dietary habits and lifestyle factors. In this study, we measured the exposure levels of 17 OCPs in the umbilical cord blood from 999 healthy pregnant women; we also administered 1000 self-reported questionnaires regarding the general characteristics and dietary habits of those women. Our results showed that ρ,ρ'-DDE, ρ,ρ'-DDT, aldrin, dieldrin, and methoxychlor, which had higher measured concentrations (2.01±1.89, 4.31±5.68, 7.29±8.74, 5.27±7.65, and 0.98±1.42ng/mL, respectively) and detection frequencies (99.69%, 100.00%, 81.79%, 75.00%, and 74.49%, respectively), were the predominant OCPs in cord blood, and the higher levels of DDTs, aldrin, dieldrin, and methoxychlor were mainly due to recent use. In addition, most of the HCHs in cord blood were derived not only from historical use of technical HCH, but also from the additional use of lindane. In addition, we found that the education level of the pregnant women and monthly household income were positively correlated with OCP levels, particularly ρ,ρ'-DDE, aldrin, and dieldrin. Furthermore, the consumption of red meat (pork, beef, and lamb), fish, and bean products may be an important contributing factor to the increased concentrations of OCPs in cord blood, while the intake of poultry and pickles was negatively correlated with aldrin level. This study is the first to provide adequate data on current OCP exposure levels in cord blood from pregnant women in the Huaihe River Basin. PMID:27123771
Ha, Yao; Zhong, Zhong; Chen, Haishan; Hu, Yijia
This study investigates the decadal variability of rainfall over China in boreal summer (June-August) since the early 1990s. Results show that the rainfall experiences an abrupt decadal change at around 2002/2003. The decadal change is statistically significant and characterized by an out-of-phase pattern between southern China (SC) and the Yellow-Huaihe River Valley (YHRV). The rainfall over SC decreases during the decade 2003-2012 compared to that in the preceding decade 1993-2002. A simultaneous decadal increase in rainfall has occurred over the YHRV. Meanwhile, a significant sea surface temperature warming appears over the western Pacific Ocean and the northern Indian Ocean after 2002 on the decadal time scale. Further analysis reveals that enhanced convections are activated over the tropical regions between 130°E and 160°E and west of 80°E due to the SST anomalies, which induce the dry air in an area of anomalous subsidence located over SC and the northern South China Sea (SCS) via zonal circulation. Accompanied by the anomalous descending flow over the northern SCS, tropical cyclone (TC) activities in the SCS also experience a concurrent decadal reduction. The decrease in landfall TCs contributes to the decadal decrease in SC rainfall since 2003. Corresponding to the anomalous descending motion that is dominant south of 30°N, an anomalous moist ascending flow develops over the YHRV at around 35°N. Meanwhile, the western Pacific subtropical high becomes stronger and extends further westward during 2003-2012, leading to enhanced moisture transport by the southwesterly in the northwestern flank of subtropical high. As a result, more precipitation occurs over the YHRV. The above analysis has revealed the physical-dynamical processes involved in the decadal changes in rainfall over China. The mechanisms behind the out-of-phase pattern of rainfall changes between SC and the YHRV that occurred at 2002/2003 are explored.
He, Y.; Cloke, H.; Li, Z.; Wetterhall, F.; Pappenberger, F.
Flooding is a wide spread and devastating natural disaster worldwide. Floods that took place in the last decade in China were ranked the worst amongst recorded floods worldwide in terms of the number of human fatalities and economic losses (Munich Re-Insurance). Rapid economic development and population expansion into low lying flood plains has worsened the situation. The last decade has seen an increase in flood preparedness across all levels of society in China. Current conventional flood prediction systems in China are neither suited to the perceptible climate variability nor the rapid pace of urbanization sweeping the country. Flood prediction systems from short-term (a few hours) to medium-term (a few days) need to be revisited and adapted to changing socio-economic and hydro-climatic realities. The latest technology requires implementation of multiple numerical weather prediction systems. The availability of a number of global ensemble weather prediction systems through the ‘THORPEX Interactive Grand Global Ensemble' (TIGGE) offers a good opportunity for an effective state-of-the-art early forecasting system. A prototype of a Novel Flood Early Warning System (NEWS) using the TIGGE database is tested in the Huai River basin located in east-central China. It is the first early flood warning system in China that uses the massive TIGGE database cascaded with river catchment models, the Xinanjiang model and a 1-D hydraulic model, to predict river discharge and flood inundation. Results from selected flood events will be presented.
Hong, Jieli; Liu, Yimin
The significant differences of atmospheric circulation between flooding in the Huaihe and Yangtze River valleys during early mei-yu (i.e., the East Asian rainy season in June) and the related tropical convection were investigated. During the both flooding cases, although the geopotential height anomalies always exhibit equivalent barotropic structures in middle to high latitudes at middle and upper troposphere, the phase of the Rossby wave train is different over Eurasian continent. During flooding in the Huaihe River valley, only one single blocking anticyclone is located over Baikal Lake. In contrast, during flooding in the Yangtze River valley, there are two blocking anticyclones. One is over the Ural Mountains and the other is over Northeast Asia. In the lower troposphere a positive geopotential height anomaly is located at the western ridge of subtropical anticyclone over Western Pacific (SAWP) in both flooding cases, but the location of the height anomaly is much farther north and west during the Huaihe River mei-yu flooding. Furthermore, abnormal rainfall in the Huaihe River valley and the regions north of it in China is closely linked with the latent heating anomaly over the Arabian Sea and Indian peninsula. However, the rainfall in the Yangtze River valley and the regions to its south in China is strongly related to the convection over the western tropical Pacific. Numerical experiments demonstrated that the enhanced latent heating over the Arabian Sea and Indian peninsula causes water vapor convergence in the region south of Tibetan Plateau and in the Huaihe River valley extending to Japan Sea with enhanced precipitation; and vapor divergence over the Yangtze River valley and the regions to its south with deficient precipitation. While the weakened convection in the tropical West Pacific results in moisture converging over the Yangtze River and the region to its south, along with abundant rainfall.
You, W. J.; Zhang, Y. L.
Huaihe River is one of the seven largest rivers in China, in which floods occurred frequently. Disasters cause huge casualties and property losses to the basin, and also make it famous for high social vulnerability to floods. Based on the latest social-economic data, the index system of social vulnerability to floods was constructed, and Catastrophe theory method was used in the assessment process. The conclusion shows that social vulnerability as a basic attribute attached to urban environment, with significant changes from city to city across the Huaihe River basin. Different distribution characteristics are present in population, economy, flood prevention vulnerability. It is important to make further development of social vulnerability, which will play a positive role in disaster prevention, improvement of comprehensive ability to respond to disasters.
Guan, Zhaoyong; Yu, Bo; Wang, Lijuan; He, Jielin; Zeng, Gang
By using the NCEP/NCAR daily reanalysis data, CMAP precipitation data , daily precipitation data of 740 stations in China and some remote sensing data, features of the short-term position variation of the west Pacific subtropical high(WPSH) during the torrential rain in Yangtze-Huaihe river valley and its possible cause are analyzed. Results show that the short-term position variation of WPSH is closely associated with the diabatic heating. During the torrential rain period, the apparent heating source and apparent moisture sink are exceptionally strong over Yangtze-Huaihe river valley( on the northwest side of WPSH )and the Bay of Bengal (to the west of WPSH). Based on the complete form of vertical vorticity tendency equation, it is found that the heating field over Yangtze-Huaihe river valley during the torrential rain period, which is in favor of the increase of cyclonic vorticity on the north side of WPSH, is unfavorable to the WPSH moving northward. And the heat source over the Bay of Bengal ,which is in favor of the increase of anti-cyclonic vorticity on the west of WPSH, may induce the westward extension of WPSH.
Yang, C.; Lin, Z.; Yu, Z.; Hao, Z.; Ju, Q.; Liu, D.
Water supply and management projects including more than 5700 reservoirs and 5000 sluice gates have been operating for the growing need of water supplies for domestic, agricultural and industrial uses in the Huaihe River basin. Extreme flood and drought events occur more frequently due to the present global climate changes, which bring new difficulties in the hydrologic simulation of various hydrologic processes in the region. In this study, a long-term continuous hydrologic simulation (1980-2006) was conducted with a coupled land surface / hydrologic model in the basin in which the dynamics of vegetation, snow, soil moisture, groundwater, terrestrial hydrology, and channel(lake) / groundwater interaction were integrated into the coupled model system. Simulated hydrographs compared well with the observed at the basin outlet in 1980s. Continuous heavy flood and drought years have occurred alternately in the Huaihe River basin since 1990s; among which streamflows were over- estimated for the dry years and simulations for the flood years were reasonable. Massive water supply emerged due to increasing industrial activities and well developed water projects at that time, which altered the local natural hydrologic cycle. The simulated results were consistent with the adjusted observed hydrographs by the annual water supply, which showed that human activities have obviously affected the natural surface rainfall-runoff process, especially in dry years. It becomes an urgent issue to integrate human activities in the hydrologic simulation.
Sun, Ruochen; Yuan, Huiling; Liu, Xiaoli; Jiang, Xiaoman
Satellite-gauge quantitative precipitation estimate (QPE) products may reduce the errors in near real-time satellite precipitation estimates by combining rain gauge data, which provides great potential to hydrometeorological applications. This study aims to comprehensively evaluate four of the latest satellite-gauge QPEs, including NASA's Tropical Rainfall Measuring Mission (TRMM) 3B42V7 product, NOAA's Climate Prediction Center (CPC) MORPHing technique (CMORPH) bias-corrected product (CMORPH CRT), CMORPH satellite-gauge merged product (CMORPH BLD) and CMORPH satellite-gauge merged product developed at the National Meteorological Information Center (NMIC) of the China Meteorological Administration (CMA) (CMORPH CMA). These four satellite-gauge QPEs are statistically evaluated over the Huaihe River basin during 2003-2012 and applied into the distributed Variable Infiltration Capacity (VIC) model to assess hydrologic utilities. Compared to the China Gauge-based Daily Precipitation Analysis (CGDPA) newly developed at CMA/NMIC, the four satellite-gauge QPEs generally depict the spatial distribution well, with the underestimation in the southern mountains and overestimation in the northern plain of the Huaihe River basin. Specifically, both TRMM and CMORPH CRT adopt simple gauge adjustment algorithms and exhibit relatively poor performance, with evidently deteriorated quality in winter. In contrast, the probability density function-optimal interpolation (PDF-OI) gauge adjustment procedure has been applied in CMORPH BLD and CMORPH CMA, resulting in higher quality and more stable performance. CMORPH CMA further benefits from a merged dense gauge observation network and outperforms the other QPEs with significant improvements in rainfall amount and spatial/temporal distributions. Due to the insufficient gauge observations in the merging process, CMORPH BLD features the similar error characteristics of CMORPH CRT with a positive bias of light precipitation and a negative
Liu, Yunlei; Chen, Jian; Lu, Shaonan; Yang, Libo; Qian, Jiazhong; Cao, Shuqing
Heavy metal contamination of water is an increasing environmental problem worldwide, and the use of aquatic plants for phytoremediation of heavy metal pollution has become an important subject of research. One key to successful phytoremediation is the identification of plants that are efficient at sequestering heavy metals. In this study, we examined the growth and heavy metal accumulation of Typha angustifolia and compared growth characteristics and tolerance mechanisms in plants from the Huaihe and Chaohu Rivers irrigated with different concentrations of lead (Pb) and cadmium (Cd). T. angustifolia from Huaihe River showed enhanced tolerance and accumulation of Pb and Cd and had greater biomass and more vigorous growth than the ecotype from Chaohu River. In addition, higher phytochelatin (PC) content and significantly higher superoxide dismutase and catalase activities were detected in T. angustifolia from Huaihe River than in T. angustifolia from Chaohu River. These findings suggest that high Pb and Cd accumulation and tolerance in T. angustifolia from Chaohu River is associated with its higher PC synthesis and better antioxidative capacity, and that the Huaihe ecotype of T. angustifolia might also be an efficient species for phytoremediation of Pb and Cd in water contaminated by heavy metals. PMID:26959972
Li, Laifang; Li, Wenhong; Tang, Qiuhong; Zhang, Pengfei; Liu, Yimin
Warm season heavy rainfall events over the Huaihe River Valley (HRV) of China are amongst the top causes of agriculture and economic loss in this region. Thus, there is a pressing need for accurate seasonal prediction of HRV heavy rainfall events. This study improves the seasonal prediction of HRV heavy rainfall by implementing a novel rainfall framework, which overcomes the limitation of traditional probability models and advances the statistical inference on HRV heavy rainfall events. The framework is built on a three-cluster Normal mixture model, whose distribution parameters are sampled using Bayesian inference and Markov Chain Monte Carlo algorithm. The three rainfall clusters reflect probability behaviors of light, moderate, and heavy rainfall, respectively. Our analysis indicates that heavy rainfall events make the largest contribution to the total amount of seasonal precipitation. Furthermore, the interannual variation of summer precipitation is attributable to the variation of heavy rainfall frequency over the HRV. The heavy rainfall frequency, in turn, is influenced by sea surface temperature anomalies (SSTAs) over the north Indian Ocean, equatorial western Pacific, and the tropical Atlantic. The tropical SSTAs modulate the HRV heavy rainfall events by influencing atmospheric circulation favorable for the onset and maintenance of heavy rainfall events. Occurring 5 months prior to the summer season, these tropical SSTAs provide potential sources of prediction skill for heavy rainfall events over the HRV. Using these preceding SSTA signals, we show that the support vector machine algorithm can predict HRV heavy rainfall satisfactorily. The improved prediction skill has important implication for the nation's disaster early warning system.
Yang, Yuan-Jian; Fu, Yun-Fei; Chen, Feng-Jiao; Zheng, Xiao-Yi; Chen, Yi-Lun
As the similar cross track scanning mode of the measurements of Tropical Rainfall Measuring Mission's (TRMM) Precipitation Radar (PR) and visible and infrared scanner (VIRS) results in near instantaneous synchronization in observing the same target, it is feasible to jointly use these two measurements to explore exactly the spectral characteristics of precipitating clouds (PCs). Meanwhile, it will effectively improve and extend the abilities to identify PCs using visible/infrared (VIR) measurements, because VIR sensors can be loaded aboard geostationary satellites with the opportunity of high sampling frequency. In this paper, PR and VIRS onboard TRMM are respectively used to capture PCs and identify their spectral signals during the Meiyu over the Yangtze-Huaihe River Valley from 1998 to 2007. Visible/infrared signals for PCs, which are the reflectance at 0.63μm and 1.6μm (referred to as RF1 and RF2, respectively), and the equivalent brightness temperature of a blackbody at 3.7μm, 10.8 μm and 12.0μm (referred to as TB3, TB4 and TB5, respectively), were derived by TRMM VIRS. Firstly, characteristics of rain rate, rain top and vertical profiles for stratiform and convective precipitations are investigated during the Meiyu periods. Moreover, VIRS individual-channel signals, and multi-channel indices for PCs of the Meiyu are evaluated quantitatively. Finally, revealed by long-term mean values, the differences of spectral signals between stratiform and convective PCs and their relationships with surface rain rates are explored.
Zhang, Qian Qian; Zhao, Jian-Liang; Ying, Guang-Guo; Liu, You-Sheng; Pan, Chang-Gui
Steroids are excreted from humans and animals and discharged with wastewaters into the environment, resulting in potential adverse effects on organisms. Based on the excretion rates from different groups of humans and animals, the emissions of seven steroids (estrone (E1), 17β-estradiol (E2), estriol (E3), testosterone (T), androsterone (A), progesterone (P), and cortisol (C)) were comprehensively estimated in 58 river basins of whole China, and their multimedia fate was simulated by using a level III fugacity multimedia model. The results showed that higher emission densities for the steroids were found in the river basins of east China than in west China. This distribution was found to be generally similar to the distribution of Gross Domestic Product (GDP) across China. E3, A, and P displayed higher emission densities than the other steroids in most of the river basins. The total excretion of steroids by humans and animals in China was estimated to be 3069 t/yr. The excretion of steroids from animals was two times larger than that from humans. After various treatments, the total emission of steroids was reduced to 2486 t/yr, of which more than 80% was discharged into the water compartment. The predicted concentrations in water were within an order of magnitude of the measured concentrations available in the literature. Owing to wastewater irrigation, more steroid mass loadings in agricultural soil were found in the basins of Haihe River and Huaihe River in comparison with the other river basins. To the best of our knowledge, this is the first report on the emissions and multimedia fate of seven steroids in the river basins of China. PMID:24964360
Li, Yiqing; Chen, Yaning; Zhang, Yaoqi; Xia, Yang
Wetlands are particularly important for conserving China's biodiversity but riparian wetlands in the Tarim River basin in western China have been reduced by 46% during the last 3 decades. The world's largest habitat for Populus euphratica, which is in the Tarim River basin, significantly shrank. To protect and restore the deteriorated ecosystems along the Tarim River and its associated wetlands, China's government initiated a multimillion dollar river restoration project to release water from upper dams to the dried-up lower reaches of the Tarim River starting in 2000. We monitored the responses of groundwater and vegetation to water recharge in the lower reaches of the river from 2000 to 2006 by establishing nine 1000-m-long transects perpendicular to the river at intervals of 20-45 km along the 320-km river course below the Daxihaizi Reservoir, the source of water conveyance, to Lake Taitema, the terminus of the Tarim River. Water recharges from the Daxihaizi Reservoir to the lower reaches of the Tarim River significantly increased groundwater levels and vegetation coverage at all monitoring sites along the river. The mean canopy size of the endangered plant species P. euphratica doubled after 6 years of water recharge. Some rare migrating birds returned to rest on the restored wetlands in summer along the lower reaches of the Tarim River. The biggest challenge facing decision makers, however, is to balance water allocation and water rights between agricultural and natural ecosystems in a sustainable way. A large number of inhabitants in the Tarim Basin depend on these limited water resources for a living. At the same time, the endangered ecosystems need to be protected. Given the ecological, socioeconomic, and sociopolitical realities in the Tarim Basin, adaptive water policies and strategies are needed for water allocation in these areas of limited water resources. PMID:22748091
Yuan, Zhe; Yan, Deng-Hua; Yang, Zhi-Yong; Yin, Jun; Yuan, Yong
Drought is a kind of extreme hydrological event. With the penetration of climate change impact, severity, areal extent, and frequency of drought are increasing, especially in Huang-Huai-Hai River Basin, which plays a key role in China's agriculture production. Analyzing the regional temporal and spatial variability in the context of climate change could provide a basis for the evasion of disasters and risk. The maximum number of consecutive dry days was selected as the indicator to analyze the decadal variability of drought severity, areal extent, and spatial variability of drought frequency in different seasons in Huang-Huai-Hai River Basin. Based on these, temporal and spatial variability of two kinds of special extreme events—consecutive drought and heavy rain after drought—were studied. The results showed that: (1) Huang-Huai-Hai River Basin mainly experienced moderate drought and severe drought. Moderate drought mainly occurs in autumn. High-frequency region of moderate drought is located in the plain of Huang-Huai-Hai River Basin, and its area is approximately 22.7 % of Huang-Huai-Hai River Basin. Severe drought often occurs in spring with high-frequency region in the upstream of the Yellow River. The area of this high-frequency region is about 6 % of Huang-Huai-Hai River Basin. (2) During 1961~2011, the areal extent of summer severe drought, autumn severe drought, and extreme drought all showed increasing trend, in which the increasing trend of the autumn severe drought area in the Yellow River has reached the significance level α = 0.05. (3) Consecutive drought of several seasons often took place in Ningxia plain and Hetao plain which lie in the northwest of the Yellow River Basin. In the recent 20 years, consecutive drought from spring to summer and consecutive drought from summer to autumn occurred frequently. Drought-flood abrupt alternation such as heavy rain after drought often occurred in summer temporally and Huaihe River Basin spatially.
Qin, Peihua; Xie, Zhenghui
To detect the frequency and intensity of precipitation extremes in China for the middle 21st century, simulations were conducted with the regional climate model RegCM4 forced by the global climate model GFDL_ESM2M under the middle emission scenario (RCP4.5). Compared with observed precipitation extremes for the reference period from 1982 to 2001, RegCM4 generally performed better in most river basins of China relative to GFDL. In the future period 2032-2051, more wet extremes will occur relative to the present period in most study areas, especially in southeast China while significantly less dry extremes will occur in arid and semiarid areas in northwest China. In contrast, areas in northwest China showed an increase in the trend of dry extremes (CDD) and a decrease in the trend of wet extremes (R95p and Rx5day), which might result in more drought in the future. Finally, we discuss in detail the possible reason of these processes, such as zonal wind, vertical wind, and water vapor. In the Huaihe river basin (HU), reduced south winds in summer (June-August) and a decrease of the upward vertical p velocity cause less future precipitation and might lead to changes of extreme events. We also completed correlation analysis between the precipitation extreme indices and the climate factors and found that the precipitation extremes were more sensitive to the annual and seasonal mean precipitation, total water vapor, and upward vertical wind relative to the geopotential height and 2 m temperature over most river basins in China. Perhaps the changes of some wet extremes could be verified partly through changes of annual precipitation due to their high consistence.
Sun, R.; Yuan, H.
Huaihe catchment plays a very important role in the political, economic, and cultural development in China. However, hydrological disasters frequently occur in Huaihe catchment, and thus hydrological simulation in this area has very important significance. The Variable Infiltration Capacity(VIC)model, a macroscale distributed hydrological model is applied to the upper Huaihe Catchment, to simulate the discharge of the basin outlet Bengbu station from 1970 to 1999. The uncertainty in the calibration of VIC model parameters has been analyzed, and the best set of parameters in the training period of 1970~1993 is achieved using the Generalized Likelihood Uncertainty Estimation (GLUE) method. The study also addresses the influence of different likelihood functions for the parameter sensitivity as well as the uncertainty of discharge simulation. Results show that among the six chosen parameters, the soil thickness of the second layer (d2) is the most sensitive one, followed by the saturation capacity curve shape parameter (B). Moreover, the parameter selection is sensitive to different likelihood functions. For example, the soil thickness of the third layer (d3) is sensitive when using Nash coefficient as the likelihood function, while d3 is not sensitive when using relative error as the likelihood function. With the 95% confidence interval, the coverage rate of the simulated discharge versus the observed discharge is small (around 0.4), indicating that the uncertainty in the model is large. The coverage rate of selecting relative error as the likelihood function is bigger than that of selecting Nash coefficient. Based on the calibration and sensitivity studies, hydrological ensemble forecasts have been established using multiple parameter sets. The ensemble mean forecasts show better simulations than the control forecast (i.e. the simulation using the best set of parameters) for the long-term trend of discharge, while the control forecast is better in the simulation of
Wang, Hai-gang; Jin, Zheng-yao; Xie, Zhi; Fan, An-chuan; Yan, Li-feng; Zhu, Bing-quan; Wang, Ji-huai
The unearthing of a large number of red-yellow colored stones in Yuhui Site, Bengbu city, Anhui province of China, which was the only site of Longshan culture appointed by "Origin of the Chinese Civilization Project" in the Huaihe River basin, has drawn a widespread attention in archaeology. The present research was undertaken to examine elements, mineral composition and thermal history of one red-yellow color stone in different positions, classified according to specialized colors, by means of synchrotron radiation X-ray fluorescence (SR-XRF), X-ray diffraction (XRD), laser Raman spectroscopy (LRS), electron probe micro-analysis (EPMA) and thermoluminescence (TL). The results show that the main body of the color stone is limonite with a large amount of quartz inclusion. The yellow substances on the surface layer of the color stone were identified as goethite (alpha-FeOOH), and the red ones as red ochre (alpha-Fe2O3+clay+silica). The internal yellow brown substances inside the stone are mainly aphanitic goethite with a number of chromites and manganese dioxide, and also with small quantity of barite and bismuth. And the color stones are without historical firing treatment. These kinds of special polymetallic ores with unique nature and complex geologic history, which were unearthed in the late neolithic site with large numbers, may be closely related to some kind of primitive religious beliefs and special sacrificial practices. PMID:24369621
Chen, Xichao; Luo, Qian; Wang, Donghong; Gao, Jijun; Wei, Zi; Wang, Zijian; Zhou, Huaidong; Mazumder, Asit
Owing to the growing public awareness on the safety and aesthetics in water sources, more attention has been given to the adverse effects of volatile organic compounds (VOCs) on aquatic organisms and human beings. In this study, 77 target VOCs (including 54 common VOCs, 13 carbonyl compounds, and 10 taste and odor compounds) were detected in typical drinking water sources from 5 major river basins (the Yangtze, the Huaihe, the Yellow, the Haihe and the Liaohe River basins) and their occurrences were characterized. The ecological, human health, and olfactory assessments were performed to assess the major hazards in source water. The investigation showed that there existed potential ecological risks (1.30 × 10 ≤ RQtotals ≤ 8.99 × 10) but little human health risks (6.84 × 10(-7) ≤ RQtotals ≤ 4.24 × 10(-4)) by VOCs, while that odor problems occurred extensively. The priority contaminants in drinking water sources of China were also listed based on the present assessment criteria. PMID:26142752
Hu, Yamin; Ding, Yihui
By using BCC_RegCM 1.0 (RegCM for short) from Beijing Climate Center (BCC), China Meteorological Administration (CMA), the Meiyu season characters over the Yangtze-Huaihe region during 1991~2005 are simulated. The major conclusions of this study may be summarized as the following: (1) RegCM can reproduce the interannual variation and the spatial distribution of the summertime precipitation and temperature in the Yangtze-Huaihe region. (2) By use of a generalized Meiyu criterion and in accordance with model-calculated precipitation and temperature, the Meiyu onset and ending date have been determined. Compared with the observation, RegCM can simulate the interannual variation of the Yangtze-Huaihe Meiyu with preferable capability for most of the normal Meiyu years (such as 1995, 1997, 2000, 2001, 2002 and 2004), especially for the rich Meiyu years of 1996, 1998 and 1999. (3) In terms of the average simulation for the recent 15a, the timings of onset and ending of Meiyu occur on June 1 and July 13, respectively, which are earlier than the climatological observation. For duration, Meiyu persists for 32 day, 3 days shorter than the observation. The index of Meiyu intensity is 2.45, while the climatological one is 3.00. Therefore, RegCM is capable of simulating the climatological Meiyu duration and intensity, while the capability of simulating the onset and ending date of Meiyu still needs to be improved.
Zhao, Junhu; Yang, Liu; Gu, Bohui; Yang, Jie; Feng, Guolin
The Eurasian teleconnection pattern (EU) is an important low-frequency pattern with well-known impacts on climate anomalies in Eurasia. The difference of low-level v-winds in several regions in the Eurasian mid-high latitudes is defined as the EU index (EUIV). In this study, the relationship between the winter EUIV and precipitation in the following summer over China is investigated. Results show that there is a significant positive (negative) correlation between the winter EUIV and the following summer precipitation over North China (the Yangtze River-Huaihe River basins). Meanwhile, an interdecadal variability exists in the interannual relationship, and the correlation has become significantly enhanced since the early 1980s. Thus, the proposed EUIV may have implications for the prediction of summer precipitation anomalies over China. In positive winter EUIV years, three cyclonic circulation anomalies are observed—over the Ural Mountains, the Okhotsk Sea, and the subtropical western North Pacific. That is, the Ural blocking and Okhotsk blocking are inactive, zonal circulation prevails in the mid-high latitudes, and the western Pacific subtropical high tends to be weaker and locates to the north of its normal position in the following summer. This leads to above-normal moisture penetrating into the northern part of East China, and significant positive (negative) precipitation anomalies over North China (the Yangtze River-Huaihe River basins), and vice versa. Further examination shows that the SST anomalies over the Northwest Pacific and subtropical central North Pacific may both contribute to the formation of EUIV-related circulation anomalies over the western North Pacific.
Ding, Yuekui; Shan, Baoqing; Zhao, Yu
We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 104 km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 104 km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m3); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01) and urban land (r = 0.998; p < 0.05); and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01). Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08–16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628
Ding, Yuekui; Shan, Baoqing; Zhao, Yu
We applied a river habitat quality (RHQ) assessment method to the Hai River Basin (HRB); an important economic centre in China; to obtain baseline information for water quality improvement; river rehabilitation; and watershed management. The results of the assessment showed that the river habitat in the HRB is seriously degraded. Specifically; 42.41% of the sites; accounting for a river length of 3.31 × 10⁴ km; were designated poor and bad. Habitat in the plain areas is seriously deteriorated; and nearly 50% of the sites; accounting for a river length of 1.65 × 10⁴ km; had either poor or bad habitats. River habitat degradation was attributable to the limited width of the riparian zone (≤5 m); lower coverage of riparian vegetation (≤40%); artificial land use patterns (public and industrial land); frequent occurrence of farming on the river banks and high volumes of solid waste (nearly 10 m³); single flow channels; and rare aquatic plants (≤1 category). At the regional scale; intensive artificial land use types caused by urbanization had a significant impact on the RHQ in the HRB. RHQ was significantly and negatively correlated with farmland (r = 1.000; p < 0.01) and urban land (r = 0.998; p < 0.05); and was significantly and positively correlated with grassland and woodland (r = 1.000; p < 0.01). Intensive artificial land use; created through urbanization processes; has led to a loss of the riparian zone and its native vegetation; and has disrupted the lateral connectivity of the rivers. The degradation of the already essentially black rivers is exacerbated by poor longitudinal connectivity (index of connectivity is 2.08-16.56); caused by reservoirs and sluices. For river habitat rehabilitation to be successful; land use patterns need to be changed and reservoirs and sluices will have to be regulated. PMID:26393628
To control source pollution and improve water quality, an understanding of the spatiotemporal characteristics of organic contaminant concentrations in affected receiving waters is necessary. The Songhua River in northeast China is the country's third-largest domestic river and lo...
Bu, Hongmei; Meng, Wei; Zhang, Yuan
Anthropogenic activities have led to water quality deterioration in many parts of the world, especially in Northeast China. The current work investigated the spatiotemporal variations of water quality in the Taizi River by multivariate statistical analysis of data from the 67 sampling sites in the mainstream and major tributaries of the river during dry and rainy seasons. One-way analysis of variance indicated that the 20 measured variables (except pH, 5-day biological oxygen demand, permanganate index, and chloride, orthophosphate, and total phosphorus concentrations) showed significant seasonal (p ≤ 0.05) and spatial (p < 0.05) variations among the mainstream and major tributaries of the river. Hierarchical cluster analysis of data from the different seasons classified the mainstream and tributaries of the river into three clusters, namely, less, moderately, and highly polluted clusters. Factor analysis extracted five factors from data in the different seasons, which accounted for the high percentage of the total variance and reflected the integrated characteristics of water chemistry, organic pollution, phosphorous pollution, denitrification effect, and nitrogen pollution. The results indicate that river pollution in Northeast China was mainly from natural and/or anthropogenic sources, e.g., rainfall, domestic wastewater, agricultural runoff, and industrial discharge. PMID:24477615
Li, Honghua; Shang, Hongtao; Wang, Pu; Wang, Yawei; Zhang, Haidong; Zhang, Qinghua; Jiang, Guibin
The concentrations and geographical distribution of hexabromocyclododecane (HBCD) were investigated in 37 composite surface sediments from seven major river drainage basins in China, including Yangtze River, Yellow River, Pearl River, Liaohe River, Haihe River, Tarim River and Ertix River. The detection frequency of HBCD was 54%, with the concentrations ranged from below limit of detection (LOD) to 206 ng/g dry weight. In general, the geographical distribution showed increasing trends from the upper reaches to the lower reaches of the rivers and from North China to Southeast China. Compared to other regions in the world, the average concentration of HBCD in sediments from Yangtze River drainage basin was at relatively high level, whereas those from other six river drainage basins were at lower or similar level. The highest HBCD concentration in sediment from Yangtze River Delta and the highest detection frequency of HBCD in Pearl River drainage basins suggested that the industrial and urban activities could evidently affect the HBCD distribution. HBCD diastereoisomer profiles showed that gamma-HBCD dominated in most of the sediment samples, followed by alpha- and beta-HBCD, which was consistent with those in the commercial HBCD mixtures. Further risk assessment reflected that the average inventories of HBCD were 18.3, 5.87, 3.92, 2.50, 1.77 ng/cm2 in sediments from Pearl River, Haihe River, Tarim River, Yellow River and Yangtze River, respectively. PMID:23586301
This study explores the time-lagged impacts of the spring sensible heat (SH) source over the Tibetan Plateau (TP) on summer rainfall anomaly in east China by using the WRF model. Numerical experiments for the 2003 case indicates that spring SH anomaly over the TP can maintains its impact until summer and leads to the overall strong atmospheric heat source, which is characterized by the enhanced both SH over the western TP and condensation latent heat to the east. The wave activity diagnosis revealed that the enhanced TP heating forces a Rossby wave train to the downstream regions. The cyclonic response to the northeast TP brings about the low level northerly anomaly over the northern China, while the anticyclonic response over the western Pacific enhances the subtropical high and the low level southerly in its western flank. As a result, cold and dry airflows from mid-high latitudes and warm and wet airflows from tropical oceans converge around the Huaihe River basin. In addition, warm advection originated from the TP induces vigorous ascending motion over the convergence belt. With such a favourable circulation condition, the eastward propagating vortexes initiated over the TP intensify the torrential rainfall processes over the Huaihe River basin. Another case study of 2001 with weak spring SH over the TP and the overall southward retreat of summer rainfall belt in east China further demonstrates the role of spring SH over the TP in regulating the interannual variability of EASM in terms of wave activity and synoptic disturbance.
Wang, Lixue; Ye, Xueyan; Du, Xinqiang
The Second Songhua River is the biggest river with the most economic value in Jilin Province, China. In recent years, with the rapid development of economy, water resources and water environment problem is getting prominent, including surface water pollution and over exploitation of groundwater resources, etc. By means of bank filtration, the Second Songhua River basin might realize the combined utilization of regional groundwater and surface water, and thus has important significance for the guarantee of water demand for industrial and agricultural production planning in the basin. The following steps were adopted to evaluate the suitability of bank filtration nearby the Scond Songhua River : Firstly, in order to focus on the most possible area, the evaluation area was divided based on the aspects of natural geographical conditions and hydraulic connection extent between river water and groundwater. Second, the main suitability indexes including water quantity, water quality, interaction intensity between surface water and groundwater, and the exploitation condition of groundwater resource, and nine sub-indexes including hydraulic conductivity, aquifer thickness, river runoff, the status of groundwater quality, the status of surface water quality, groundwater hydraulic gradient, possible influence zone width of surface water under the condition of groundwater exploitation, permeability of riverbed layer and groundwater depth were proposed to establish an evaluation index system for the suitability of river bank filtration. Thirdly, Combined with the natural geography, geology and hydrogeology conditions of the Second Songhua River basin, the ArcGIS technology is used to complete the evaluation of the various indicators. According to the weighted sum of each index, the suitability of river bank filtration in the study area is divided into five grades. The evaluation index system and evaluation method established in this article are applicable to the Second Songhua
Su, F.; Xie, Z.; Liang, X.
In this study, the land surface scheme (LSS) of VIC (Variable Infiltration Capacity) model is used to simulate streamflows of major river basins in China where the new surface runoff parameterization of VIC that represents both Horton and Dunne runoff generation mechanisms with the framework of considering subgrid spatial scale soil heterogeneity is applied. The entire area of China is represented by 2604 cells with a resolution of 60kmA60km for each cell. The VIC model is applied to each grid cell over each basin. A routing scheme is run offline which takes daily VIC surface and subsurface runoff as input to obtain model simulated streamflows at the outlets of study basins. Preparation of the forcing data, and soil and vegetation parameters needed by the VIC model for the entire area of China will be described, and some of the data issues will be addressed and discussed. The VIC streamflow simulations over a few river basins will be presented and compared with the observations.
Tang, Wenzhong; Mao, Zhanpo; Zhang, Hong; Shan, Baoqing; Zhao, Yu; Ding, Yuekui
The competition for water resources between humans and river ecosystems is becoming ever more intense worldwide, especially in developing countries. In China, with rapid socioeconomic development, water resources to maintain river ecosystems are progressively decreasing, especially in the Hai River Basin (HRB), which has attracted much attention from the Chinese government. In the past 56 years, water resources have continuously decreased in the basin, such that there is 54.2 % less surface water now compared with then. Water shortages, mainly due to local anthropogenic activities, have emerged as the main limiting factor to river ecological restoration in the HRB. However, the South-to-North Water Diversion Project, the largest such project in the world, presents a good opportunity for ecological restoration of rivers in this basin. Water diverted from the Danjiangkou Reservoir will restore surface water resources in the HRB to levels of 30 years ago and will amount to more than 20 billion m(3). Our findings highlight the fact that water resources are crucial for river ecological restoration. PMID:25142344
Kliucininkaite, Lina; Disse, Markus
Tarim River is one of the longest inland rivers in the world. It flows its water in the northern part of the Taklamakan desert in Xinjiang, North-west of China, which is a very hostile region due its climatic conditions and particularly due to low precipitation and very high evaporation rates. During the past five decades intensive exploitation of water resources, mainly by agricultural activities, has changed the temporal and spatial distribution of them and caused serious environmental problems in the Tarim River Basin. The support measures for oasis management along the Tarim River under climatic and societal changes became the overarching goal of this research. The temperature has risen by nearly 1° C over the past 50 years in the Tarim River Basin so more water was available in the mountainous areas of Xinjiang, leading to an increasing trend of the headstream discharges of the Tarim Basin. Aksu, Hotan and Yarkant Rivers are three tributaries of the Tarim River, as well as its main water suppliers. However, under the condition of water increase with the volume of 25×108 m3 in headstreams in recent 10 years, the water to the mainstream has increased less than 108 m3 (in Alar hydrological station), which is less than 3% of the increased water volume of runoff. Moreover, the region is one of the biggest cotton and other cash crops producers in China. In addition, expansion of urban and, in particular, of irrigation areas have caused higher water consumption at different parts of the river, leading to severe ecological effects on rural areas, especially in the lower reaches. Moreover, it also highly affects groundwater level and quality. The aim of this research is to support decision makers, planners and engineers to find right measures in the area for the further development of the region, as well as adaptation to changing climate. Different scenarios for water resource management, as well as water distribution and allocation in a more efficient and water
Disse, M.; Keilholz, P.; Rumbaur, C.; Thevs, N.
Within the Taklimakan Desert of Northwestern China, an area renowned for its extreme climate and vulnerable ecosystems, lies one of the largest inland rivers in the world, the Tarim River. Because the Tarim River is located in a remote area from the oceans, rainfall is extremely rare (less than 50 mm per year) but potential evaporation is high (3000 mm). Thus, the major source of water discharge comes from snowmelt and glacier-melt in the mountains. Though the water discharge into the Tarim River has experienced an increase over the past ten years, global climate change forecasts predict this water supply to decline within the century. The Tarim River is the major source of water in Northwestern China, and has become the hub of many economic activities related to agriculture and urban life. Over the past 50 years increased activity in the area has led to a severe decline in river flow. Both human and natural ecosystems have been impacted by water diversions. Since rainfall is rare, the majority of vegetation in this area depends solely on groundwater for survival, and plants are experiencing stress caused by decreasing groundwater levels. Recently nearby cities have experienced severe dust storms caused by the shrinking of the vegetative region along the river. SuMaRiO (Sustainable Management of River Oases) is a bundle project between Germany and China working to contribute to a sustainable land management which explicitly takes into account ecosystem functions (ESF) and ecosystem services (ESS). In a transdisciplinary research process, SuMaRiO will identify realizable management strategies, considering social, economic and ecological criteria. SuMaRiO is developing tools to work with Chinese decision makers to implement sustainable land management strategies. In addition, research is being conducted to estimate climate change impacts, floodplain biodiversity, and water runoff characteristics. The overarching goal of SuMaRiO is to support oasis management along
Cuo, L.; Zhou, B.; Li, J.
Yellow River, Yangtze River and Lan Cang River are major river systems supporting billions of people in South East Asia and China. Source region of Yellow River, Yangtze River and Lan Cang River (Three Rivers) is located in Qinghai Province, China. Recently, Chinese government started a conservation project in the source region of the Three Rivers called “Convert Agricultural Field to Forest and Grassland”. Xia Ying River Basin is a sub-basin located in the source region of the Three River Basin. The upper Xia Ying River Basin has experienced dramatic land cover change since 2006. Before 2006, upper Xia Ying River Basin hill slope was agricultural field. Coniferous trees and bush vegetation were planted on the slope greater than 70 degree in the upper Xia Ying River Basin in 2006. The objective of the study is to investigate the water balance term change in the Xia Ying River Basin because of the conservation project. This study will use Landsat and MODIS imagery to classify and quantify land cover classes before and after land cover conversion. Water balance terms including runoff and evaportranspiration will be simulated using a land surface model to investigate water balance term change due to land cover change. The study serves as a pilot study for the investigation of hydrological change in the entire source region of the Three River Basin during the past 50 years.
Liu, C.; Lang, Y.; Tian, L.; Ding, H.; Strauss, H.; Zhao, Z.; Li, S.; Li, X.; Hu, J.
Sulfur is widely distributed in the environment by volcanism, volatile emissions, precipitation, acid mine drainage and anthropogenic activity. Since the industrial revolution, the atmospheric sulfur cycle has been dominated by anthropogenic sources. Combustion of sulfur-containing fossil fuels release large quantities of sulfur dioxide into Earth's atmosphere annually. The cycling of sulfur, among those of many elements, is seriously disturbed by human activities at the earth's surface. Therefore, it is important to obtain a better understanding of sources and cycling processes of sulfur in river basins. For this purpose, we have measured the sulfur isotope composition of sulfate and its concentration for Changjiang (Yangtze River), Huanghe (Yellow River), Liaohe (Liao River), and Songhuajiang (Songhua River) in China. The sulfate fluxes of the major rivers in southern China are significantly larger as compared with the rivers in northern China. Sulfur isotopic compositions (δ34S) of sulfate in the rivers do not show a variation trend from southern to northern China. The sulfate δ34S values are 4.3‰~9.8‰ for Changjiang, 5.0‰~10.0‰ for most of river waters of Huanghe, and 2.0‰~27.0‰ for Songhuajiang. For Zhujiang (Pearl River), three sulfate δ34S values are from 1.0‰~6.9‰. The coal produced in southern China is generally of lower δ34S values as compared with that in northern China. The distributions of the sulfate δ34S values of the river waters of are generally lower in southern China, showing the contribution of atmospheric deposition of sulfur into the river water. Three main sources, atmospheric deposition (mostly anthropogenic), dissolution of sulfate evaporate, oxidation of sulfide minerals and/or sulfur-containing organic matter in soil, have been recognized for the sulfate in the rivers. Relative contributions of the different sulfur sources into the sulfate of the rivers are different, suggesting that sulfur cycling in the different
Zhao, Y. W.; Yang, Z. F.
Due to the increasingly serious ecological degradation of river systems, the river health research has attracted more and more attention of the researchers and decision-makers. This paper aims to integrate the fuzzy assessment method with analytic hierarchy process to establish the integrative fuzzy hierarchical assessment model, thus combing qualitative analysis and quantitative assessment and overcoming the disadvantages of subjectivity of the previous evaluation methods. The results show that the proposed assessment method is able to reveal how the river system is disturbed by human activities. Finally, the integrative fuzzy hierarchical method is validated and applied to the case study of Yong River in Ningbo City, China.
Thomas, R.P.; Conrad, S.H.; Jeppesen, D.M.; Engi, E.
This report presents the preliminary results of an analysis of China`s water resources, part of an effort undertaken by the National Intelligence Council Medea scientists to improve the understanding of future food production and consumption in the People`s Republic of China. A dynamic water model was developed to simulate the hydrological budgetary processes in five river drainage basins located in northeastern, central, and southern China: the Chang Jiang (Yangtse River), Huanghe (Yellow River), Haihe, Huaihe, and Liaohe. The model was designed to assess the effects of changes in urban, industrial, and agricultural water use requirements on the availability of water in each basin and to develop estimates of the water surpluses and/or deficits in China through the year 2025. The model imposes a sustainable yield constraint, that is, groundwater extraction is not allowed to exceed the sustainable yield; if the available water does not meet the total water use requirements, a deficit results. An agronomic model was also developed to generate projections of the water required to service China`s agricultural sector and compare China`s projected grain production with projected grain consumption requirements to estimate any grain surplus and/or deficit. In future refinements, the agronomic model will interface directly with the water model to provide for the exchange of information on projected water use requirements and available water. The preliminary results indicate that the Chang Jiang basin will have a substantial surplus of water through 2025 and that the Haihe basin is in an ongoing situation. The agricultural water use requirements based on grain production indicate that an agricultural water deficit in the Haihe basin begins before the onset of the modeling period (1980) and steadily worsens through 2025. This assumption is confirmed by reports that groundwater mining is already under way in the most intensely cultivated and populated areas of northern China.
Lou, Shufang; Lei, Bingli; Feng, Chenglian; Xu, Jie; Peng, Wei; Wang, Yipei
Sediments are the ultimate sink for many toxic organic contaminants released into aquatic environment. The present study evaluated the toxicity effect of 13 surface sediment samples from Huangpu River and Suzhou River, East China using two-hybrid yeast bioassays for estrogenic and thyroidal effects and H4IIE rat hepatoma cell bioassay for ethoxyresorufin O-deethylase (EROD) activity. Toxicity was expressed as 17β-estradiol equivalent (E2-EQ), 3,3',5-triiodothyronine equivalent (T3-EQ), and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent (TEQ). At the same time, the causality between the observed EROD activity and concentrations of polycyclic aromatic hydrocarbons (PAHs) was examined. The results showed that the total estrogenic effects in sediments ranged from 0.06 to 1.21 μg E2-EQ kg(-1) dry weight (dw), the thyroidal effects ranged from 4.68 to 69.9 μg T3-EQ kg(-1) dw, and significantly positive correlations were found between lgT3-EQs and lgE2-EQs. The AhR agonist effects varied from 26.5 to 148.3 ng TEQ kg(-1) dw. Chemical analysis-derived TEQs contributed by PAHs ranged from 13.8 to 66.0 ng kg(-1) dw accounting for 27.2-109.9 % with mean of 48.9 % of TEQbio, indicating that PAHs made important contributions to the EROD effects of sediment extracts from the two rivers. The present study would provide meaningful information for further analysis and risk evaluation for organic pollutants in Huangpu River and Suzhou River. PMID:27094279
Chen, Huopo; Sun, Jianqi; Fan, Ke
Based on daily precipitation data, the spatial-temporal features of heavy rainfall events (HREs) during 1960-2009 are investigated. The results indicate that the HREs experienced strong decadal variability in the past 50 years, and the decadal features varied across regions. More HRE days are observed in the 1960s, 1980s, and 1990s over Northeast China (NEC); in the 1960s, 1970s, and 1990s over North China (NC); in the early 1960s, 1980s, and 2000s over the Huaihe River basin (HR); in the 1970s-1990s over the mid-lower reaches of the Yangtze River valley (YR); and in the 1970s and 1990s over South China (SC). These decadal changes of HRE days in eastern China are closely associated with the decadal variations of water content and stratification stability of the local atmosphere. The intensity of HREs in each sub-region is also characterized by strong decadal variability. The HRE intensity and frequency co-vary on the long-term trend, and show consistent variability over NEC, NC, and YR, but inconsistent variability over SC and HR. Further analysis of the relationships between the annual rainfall and HRE frequency as well as intensity indicates that the HRE frequency is the major contributor to the total rainfall variability in eastern China, while the HRE intensity shows only relative weak contribution.
Liu, Mingliang; Tian, Hanqin; Lu, Chaoqun; Xu, Xiaofeng; Chen, Guangsheng; Ren, Wei
SummaryLittle is known about how the terrestrial hydrological cycle responds to multiple environmental changes at large spatial scale and over long time period. Here, we applied a well calibrated and verified ecosystem model (the Dynamic Land Ecosystem Model, DLEM), in conjunction with newly developed data sets of multiple environmental factors including land use change, climate variability, elevated atmospheric carbon dioxide (CO2), nitrogen deposition, ozone pollution, and nitrogen fertilizer application, to characterize the spatial and temporal patterns of evapotranspiration (ET) and runoff in eastern China during 1961-2005 and further quantified the relative contributions of multiple environmental factors to these patterns at both basin and regional scales. The simulation results indicated that annual ET in the study area had a significantly increasing trend from 1961 to 2005. Yet there were no significant changing trends for estimated runoff and net water balance (precipitation minus ET). Substantial spatial heterogeneities in ET and runoff were observed. Annual ET increased in all basins except Yellow River Basin. Runoff increased in the southern part of the study area (including Pearl River and the Southeast basin), but decreased in northern part of the study area, particularly in Haihe and Huaihe river basins. Factorial analysis showed that climate change was the dominant factor responsible for the interannual variations in ET and runoff in the past 45 years. Land use change (including land conversions and land management practices) yielded minor effects on the interannual variations in ET and runoff but caused relatively large effects over long-term period. For the accumulated change in ET at basin scale, climate change was the dominant factor in the basins of Song-Liao, Pearl River, while land use change contributed the most in the basin of Haihe, Huaihe, and Yellow River. Climate change was the dominant factor controlling runoff change in all basins
Shan, Baoqing; Ding, Yuekui; Zhao, Yu
The river ecosystem in the Hai River Basin (HRB), an important economic region in China, is seriously degraded. With the aim of river restoration in the HRB, we developed a method to assess the river's ecological status and conducted a preliminary application of the method. The established method was a predictive model, which used macroinvertebrates as indicator organisms. The river's ecological status was determined by calculating the ratio of observed to expected values (O/E). The method included ecoregionalization according to natural factors, and the selection of reference sites based on combinations of habitat quality and macroinvertebrate community. Macroinvertebrate taxa included Insecta, Crustacea, Gastropoda, and Oligochaeta, with 39 families and 95 genera identified in the HRB. The HRB communities were dominated by pollution tolerant taxa, such as Lymnaeidae, Chironomus, Limnodrilus, Glyptotendipes, and Tubifex. The average Shannon-Wiener index was 1.40±0.5, indicating a low biodiversity. In the river length of 3.31×10(4) km, 55% of the sites were designated poor, with a bad ecological status. Among nine secondary river systems, Luan and Zi-ya had the best and worst river conditions, respectively. Only 17 reference site groups were selected for river management in the 41 ecoregions examined. This study lays the foundation for river restoration and related research in the HRB, and we anticipate further developments of this novel method. PMID:26899653
Three innovations in water and soil conservancy technology in the Pearl River Delta of South China, i.e., dike building, land reclamation, and dike-pond systems, were examined from a historical perspective. They were found to best reflect local farmers' efforts to cope with the challenges of various water disasters and to build a harmonious relationship with the changed environment. These technologies were critical to the agricultural success and sustainability over the past 2000 years, and reflected local farmers' wisdom in balancing land use and environmental conservation. Imprudent use of a new agricultural technology could damage the environment, and could disturb the human-environment relationship, as evidenced by the more frequent flooding that followed inappropriate dike building and premature reclamation. It is suggested that as the urbanization and industrialization process in the delta region continues, the kind of thinking that made the water and soil conservancy sustainable needs to be incorporated into the design of similar technologies for water use and river basin management today. PMID:17240525
Ma, Chong; Pan, Suli; Wang, Guoqing; Liao, Yufang; Xu, Yue-Ping
Global warming brings a huge challenge to society and human being. Understanding historic and future potential climate change will be beneficial to regional crop, forest, and water management. This study aims to analyze the precipitation and temperature changes in the historic period and future period 2021-2050 in the Xiangjiang River Basin, China. The Mann-Kendall rank test for trend and change point analysis was used to analyze the changes in trend and magnitude based on historic precipitation and temperature time series. Four global climate models (GCMs) and a statistical downscaling approach, LARS-WG, were used to estimate future precipitation and temperature under RCP4.5. The results show that annual precipitation in the basin is increasing, although not significant, and will probably continue to increase in the future on the basis of ensemble projections of four GCMs. Temperature is increasing in a significant way and all GCMs projected continuous temperature increase in the future. There will be more extreme events in the future, including both extreme precipitation and temperature.
Khan, Muhammad Imran; Liu, Dong; Fu, Qiang; Azmat, Muhammad; Luo, Mingjie; Hu, Yuxiang; Zhang, Yongjia; Abrar, Faiz M.
Variability in precipitation is critical for the management of water resources. In this study, the research entropy base concept was applied to investigate spatial and temporal variability of the precipitation during 1964-2013 in the Songhua River basin of Heilongjiang Province in China. Sample entropy was applied on precipitation data on a monthly, seasonally, annually, decade scale and the number of rainy days for each selected station. Intensity entropy and apportionment entropy were used to calculate the variability over individual year and decade, respectively. Subsequently, Spearman's Rho and Mann-Kendall tests were applied to observe for trends in the precipitation time series. The statistics of sample disorder index showed that the precipitation during February (mean 1.09, max. 1.26 and min. 0.80), April (mean 1.12, max. 1.29 and min. 0.99) and July (mean 1.10, max. 1.20 and min. 0.98) contributed significantly higher than those of other months. Overall, the contribution of the winter season was considerably high with a standard deviation of 0.10. The precipitation variability on decade basis was observed to increase from decade 1964-1973 and 1994-2003 with a mean value of decadal apportionment disorder index 0.023 and 0.053, respectively. In addition, the Mann-Kendall test value (1.90) showed a significant positive trend only at the Shangzhi station.
Zhao, Tongtiegang; Zhao, Jianshi; Hu, Hongchang; Ni, Guangheng
Oceanic evaporation via the East Asian Monsoon (EAM) has been regarded as the major source of precipitation over China, but a recent study estimated that terrestrial evaporation might contribute up to 80% of the precipitation in the country. To explain the contradiction, this study presents a comprehensive analysis of the contribution of oceanic and terrestrial evaporation to atmospheric moisture and precipitation in China's major river basins. The results show that from 1980 to 2010, the mean annual atmospheric moisture (precipitable water) over China was 13.7 mm, 39% of which originates from oceanic evaporation and 61% from terrestrial evaporation. The mean annual precipitation was 737 mm, 43% of which originates from oceanic evaporation and 57% from terrestrial evaporation. Oceanic evaporation makes a greater contribution to atmospheric moisture and precipitation in the East Asian Monsoon Region in South and East China than terrestrial evaporation does. Particularly, for the Pearl River and southeastern rivers, oceanic evaporation contributes approximately 65% of annual precipitation and more than 70% of summer precipitation. Meanwhile, terrestrial evaporation contributes more precipitation in northwest China due to the westerly wind. For the northwestern rivers, terrestrial evaporation from the Eurasian continents contributes more than 70% of precipitation. There is a linear relation between mean annual precipitation and the contribution of oceanic evaporation to precipitation, with a correlation coefficient of 0.92, among the ten major river basins in China.
Kissel, Catherine; Liu, Zhifei; Li, Jinhua; Wandres, Camille
The use of the marine sedimentary magnetic properties, as tracers for changes in precipitation rate and in oceanic water masses transport and exchanges, implies to identify and to characterize the different sources of the detrital fraction. This is of particular importance in closed and/or marginal seas such as the South China Sea. We report on the magnetic properties of sedimentary samples collected in three main Asian rivers draining into the South China Sea: the Pearl, Red, and Mekong Rivers. The geological formations as well as the present climatic conditions are different from one catchment to another. The entire set of performed magnetic analyses (low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of three-axes IRM, hysteresis parameters, FORC diagrams, and low-temperature magnetic measurements) allow us to identify the magnetic mineralogy and the grain-size distribution when magnetite is dominant. Some degree of variability is observed in each basin, illustrating different parent rocks and degree of weathering. On average it appears that the Pearl River is rich in magnetite along the main stream while the Mekong River is rich in hematite. The Red River is a mixture of the two. Compared to clay mineral assemblages and major element contents previously determined on the same samples, these new findings indicate that the magnetic fraction brings complementary information of great interest for environmental reconstructions based on marine sediments from the South China Sea.
Johnson, Gary E.; Rainey, William S.
This paper provides a scientific approach to eco-design of river fishways to allow upstream movement of fish past new and existing dams in China. This eco-design approach integrates principles of fish ecology/behavior and engineering, a scientific field also known as bio-engineering or eco-hydraulics. We define a fishway as a structure or mechanism to convey fish upstream past a dam. Man-made or natural stream beds can be part of the fishway mechanism. Fish include bony and non-bony fishes, and upstream passage is the concern here, not downstream passage. The problem is dams block access to upstream habitat used for spawning, rearing, and refuge, i.e., dams decrease habitat connectivity. A solution to alleviate this problem is to design fishways, preferably while the dam is being designed, but if necessary, as retrofits afterward to provide a route that fish can and will use to pass safely upstream without undue delay. Our eco-design approach for fishways involves eight steps: 1) identify the primary species of importance; 2) understand basic ecology and behavior of these fish; 3) characterize the environmental conditions where passage is or will be blocked; 4 identify fishway alternatives and select a preferred alternative; 5) establish eco-design criteria for the fishway, either from management agencies or, if necessary, developed specifically for the given site; 6) where needed, identify and perform research required to resolve critical uncertainties and finalize the eco-design criteria; 7) apply the eco-design criteria and site-specific considerations to design the fishway, involving peer-review by local stakeholders in the process; 8) build the fishway, monitor its effectiveness, and apply the lessons learned. Example fishways are described showing a range of eco-designs depending on the dam site and fish species of concern. We apply the eco-design principles to recommend an approach and next steps for a fishway to pass fish upstream at Hanfeng Dam, an
Rumbaur, C.; Thevs, N.; Disse, M.; Ahlheim, M.; Brieden, A.; Cyffka, B.; Doluschitz, R.; Duethmann, D.; Feike, T.; Frör, O.; Gärtner, P.; Halik, Ü.; Hill, J.; Hinnenthal, M.; Keilholz, P.; Kleinschmit, B.; Krysanova, V.; Kuba, M.; Mader, S.; Menz, C.; Othmanli, H.; Pelz, S.; Schroeder, M.; Siew, T. F.; Stender, V.; Stahr, K.; Thomas, F. M.; Welp, M.; Wortmann, M.; Zhao, X.; Chen, X.; Jiang, T.; Zhao, C.; Zhang, X.; Luo, J.; Yimit, H.; Yu, R.
The Tarim River Basin, located in Xinjiang, NW China, is the largest endorheic river basin of China and one of the largest in whole Central Asia. Due to the extremely arid climate with an annual precipitation of less than 100 mm, the water supply along the Aksu and Tarim River solely depends on river water. This applies for anthropogenic activities (e.g. agriculture) as well as for the natural ecosystems so that both compete for water. The on-going increase of water consumption by agriculture and other human activities in this region has been enhancing the competition for water between human needs and nature. Against this background, 11 German and 6 Chinese universities and research institutes formed the consortium SuMaRiO (www.sumario.de), which aims at gaining a holistic picture of the availability of water resources in the Tarim River Basin and the impacts on anthropogenic activities and natural ecosystems caused by the water distribution within the Tarim River Basin. The discharge of the Aksu River, which is the major tributary to the Tarim, has been increasing over the past 6 decades due to enhanced glacier melt. Alone from 1989 to 2011, the area under agriculture more than doubled. Thereby, cotton became the major crop and there was a shift from small-scale farming to large-scale intensive farming. The major natural ecosystems along the Aksu and Tarim River are riparian ecosystems: Riparian (Tugai) forests, shrub vegetation, reed beds, and other grassland. Within the SuMaRiO Cluster the focus was laid on the Tugai forests, with Populus euphratica as dominant tree, because the most productive and species-rich natural ecosystems can be found among those forests. On sites with groundwater distance of less than 7.5 m the annual increments correlated with river runoffs of the previous year. But, the further downstream along the Tarim River, the more the natural river dynamics ceased, which impacts on the recruitment of
Song, X; Ravesteijn, W; Frostell, B; Wennersten, R
The emerging water crisis in China shows that the current institutional frameworks and policies with regard to water resources management are incapable of achieving an effective and satisfactory situation that includes Integrated River Basin Management (IRBM). This paper analyses this framework and related policies, examines their deficiencies in relation to all water stress problems and explores alternatives focusing on river basins. Water resources management reforms in modern China are reviewed and the main problems involved in transforming the current river management system into an IRBM-based system are analysed. The Huai River basin is used as an example of current river basin management, with quantitative data serving to show the scale and scope of the problems in the country as a whole. The institutional reforms required are discussed and a conceptual institutional framework is proposed to facilitate the implementation of IRBM in China. In particular, the roles, power and responsibilities of River Basin Commissions (RBCs) should be legally strengthened; the functions of supervising, decision-making and execution should be separated; and cross-sectoral legislation, institutional coordination and public participation at all levels should be promoted. PMID:20107277
Lin, Kairong; Lian, Yanqing; Chen, Xiaohong; Lu, Fan
The Dongjiang River, one of the tributaries of the Pearl River, serves as the critical water source for Guangdong Province and the District of Hong Kong in China. In this study, the change trend and change points of flow at three main gaging stations in the Dongjiang River were analyzed using the nonparametric Mann-Kendall test and Pettitt-Mann-Whitney change-point statistics. Flow regime changes in the Dongjiang River were quantified by using both the Indicators of Hydrologic Alteration (IHA) parameters and eco-statistics, such as ecosurplus and ecodeficit. It was found that the change trend for annual median flow in the Dongjiang River increased over the past 60 years, with the major change occurring sometime between 1970 and 1974. IHA analyses showed that the magnitude of monthly flow decreased during the flood period, but increased greatly during the dry period. The median date of the one-day minimum flow moved ahead, and the duration of low pulse for the Dongjiang River was reduced significantly because of reservoir construction and operations. The IHA-based Dundee Hydrological Regime Alteration Method analysis indicated that all three stations have experienced a moderate risk of impact since 1974. The eco-statistical analyses showed that the majority of the flows appeared to be ecosurplus at all three locations after 1974, while flows with less than 30%, or higher exceedance probability, had ecodeficit in the summer flood period due to heavy reservoir operations.
Cuo, L.; Zhao, L.; Zhou, B.
Yellow River supports 30% of China's population and 13% of China's total cultivated area. About 35% of the Yellow River discharge comes from the upper Yellow River Basin. Seasonally frozen, continuous and isolated permafrost soils coexist and cover the entire upper Yellow River Basin. The spatial distribution of various frozen soisl is primarily determined by the elevation in the basin. Since the past five decades, air temperature has increased by a rate of 0.03 C/year in the upper Yellow River Basin. Many studies reported the conversions of continuous to isolated permafrost soil, permafrost soil to seasonally frozen soil and the thickening of the active layer due to rising temperature in the basin. However, very few studies reported the impact of the change of frozen soil on the water balance in the basin. In this study, the Variable Infiltration Capacity (VIC) model is applied in the upper Yellow River Basin to study the change of frozen soil and its impact on the water balance. Soil temperature and soil liquid content measured up to 3 m below ground surface at a number of sites in the upper Yellow River Basin and the surroundings are used to evaluate the model simulation. Streamflow is also calibrated and validated using historical streamflow records. The validated VIC model is then used to investigate the frozen soil change and the impact of the change on water balance terms including surface runoff, baseflow, evapotranspiration, soil water content, and streamflow in the basin.
Alligatorweed (Alternanthera philoxeroides (Mart.) Griseb), is a problematic and difficult to manage invasive weed. The recent invasion in the upper Xiaoqing River, northern China extends its range northwards through almost five degrees latitude and 500 km from the northern limit and main invasion a...
Carbonaceous aerosol is one of the important constituents of fine particulate matter (PM2.5) in Southern China, including the Pearl River Delta (PRD) region and Hong Kong (HK). During the study period (October and December of 2002, and March and June of 2003), the monthly average...
Che, Yue; Li, Wen; Shang, Zhaoyi; Liu, Chen; Yang, Kai
River networks have both ecological and social benefits for urban development. However, river networks have suffered extensive destruction as a result of urbanization and industrialization, especially in China. River restoration is a growth business but suffers poor efficiency due to a lack of social understanding. Assessing the benefits of river system restoration and recognizing public preferences are critical for effective river ecosystem restoration and sustainable river management. This study used a choice experiment with a multinomial logit model and a random parameter logit model to assess respondents' cognitive preferences regarding attributes of river networks, and their possible sources of heterogeneity. Results showed that riverfront condition was the attribute most preferred by respondents, while stream morphology was the least preferred. Results also illustrated that the current status of each of three river network attributes was not desirable, and respondents would prefer a river network with a "branch pattern," that is "limpid with no odor," and "accessible with vegetation." Estimated willingness to pay was mainly affected by household monthly income, residential location, and whether respondents had household members engaged in a water protection career. The assessment results can provide guidance and a reference for managers, sponsors, and researchers. PMID:25011532
Che, Yue; Li, Wen; Shang, Zhaoyi; Liu, Chen; Yang, Kai
River networks have both ecological and social benefits for urban development. However, river networks have suffered extensive destruction as a result of urbanization and industrialization, especially in China. River restoration is a growth business but suffers poor efficiency due to a lack of social understanding. Assessing the benefits of river system restoration and recognizing public preferences are critical for effective river ecosystem restoration and sustainable river management. This study used a choice experiment with a multinomial logit model and a random parameter logit model to assess respondents' cognitive preferences regarding attributes of river networks, and their possible sources of heterogeneity. Results showed that riverfront condition was the attribute most preferred by respondents, while stream morphology was the least preferred. Results also illustrated that the current status of each of three river network attributes was not desirable, and respondents would prefer a river network with a "branch pattern," that is "limpid with no odor," and "accessible with vegetation." Estimated willingness to pay was mainly affected by household monthly income, residential location, and whether respondents had household members engaged in a water protection career. The assessment results can provide guidance and a reference for managers, sponsors, and researchers.
Guo, Leicheng; He, Qing
This study focuses on suspended sediments and in situ flocculation in the Yangtze River, with the goal of improving our understanding of the relationship between freshwater and estuarine flocculation. A field survey with state-of-the-art instruments was carried out in January 2008 in the reach from downstream of the Three Gorges Dam to the estuary. The data show that in situ floc mean diameters range from 22 to 182 μm in the river, whereas the median dispersed grain sizes are 4.4-11.4 μm. This demonstrates that flocculation is an important process during the transport of suspended sediments along the river. The flocculation characteristics, suspended sediment concentration and dispersed grain sizes all vary longitudinally in the main stream of the Yangtze River. Biochemical factors are likely be more significant in the freshwater flocculation than in the estuary, where hydrodynamics and biochemical factors are both important. Flocculation is found in the freshwater river, in the estuary and in coastal waters, which indicates that dynamic break-up/reflocculation processes take place during the suspended sediment transport. The freshwater flocs may behave as parent flocs to the estuarine flocculation. This study enhances our understanding of flocculation from estuarine and coastal areas to fresh river systems and provides insights into the effects of input of riverine flocs to the estuarine flocculation and into the sources and fate of flocs.
Xi, Haiyang; Feng, Qi; Si, Jianhua; Chang, Zongqiang; Cao, Shengkui
Water resources have been overexploited for agricultural irrigation and industrial production in the upper and middle reaches of the Heihe River, northwestern China. Due to inadequate water resources management, the runoff entering into the lower reaches has been continuously reduced in recent years. The Heihe River is the primary recharge source for the groundwater of the lower reaches, so the decrease in runoff has caused the groundwater level to decline. As a result, a series of ecological and environmental problems has now appeared in the lower reaches, including river-flow interruptions, drying up of associated lakes, degeneration of vegetative cover and so on. In view of these issues, the National Water Diversion Project was put into practice in July 2000. It has significantly increased the quantity and frequency of flows entering into the lower reaches of the Heihe River, and has recharged the groundwater and improved the water quality to some degree along the length of the river. The water deliveries have had obvious influences on the groundwater in the lower reaches. The groundwater level increase and groundwater quality improvement have been of great benefit in restoring the ecological environment that was destroyed in past years.
Xu, Z.; Zuo, D.
The Wei River is the largest tributary of the Yellow River in China and it is suffering from water scarcity and water pollution. In order to quantify the amount of water resources in the study area, a hydrological modelling approach was applied by using SWAT (Soil and Water Assessment Tool), calibrated and validated with SUFI-2 (Sequential Uncertainty Fitting program) based on river discharge in the Wei River basin (WRB). Sensitivity and uncertainty analyses were also performed to improve the model performance. Water resources components of blue water flow, green water flow and green water storage were estimated at the HRU (Hydrological Response Unit) scales. Water resources in HRUs were also aggregated to sub-basins, river catchments, and then city/region scales for further analysis. The results showed that most parts of the WRB experienced a decrease in blue water resources between the 1960s and 2000s, with a minimum value in the 1990s. The decrease is particularly significant in the most southern part of the WRB (Guanzhong Plain), one of the most important grain production basements in China. Variations of green water flow and green water storage were relatively small on the spatial and temporal dimensions. This study provides strategic information for optimal utilization of water resources and planning of cultivating seasons in the Wei River basin.
Xie, Ying; Li, Xuyong; Wang, Huiliang; Li, Wenzan
The analysis of river pollution and assessment of spatial and temporal variation in hydrochemistry are essential to river water pollution control in the context of rapid economic growth and growing pollution threats in China. In this study, we focused on hydrochemical characteristics of the Luanhe River Basin (China) and evaluation of 12 hydrochemical variables obtained from 32 monitoring stations during 2001-2010. In each study year, the streams were monitored in the three hydrological periods (April, August, and October) to observe differences in the impacts of agricultural activity and rainfall pattern. Multivariate statistical methods were applied to the data set, and the river water hydrochemical characteristics were assessed using the water quality identification index (WQIIM). The results showed that parameters had variable contribution to water quality status in different months except for ammonia nitrogen (NH4-N) and total nitrogen (TN), which were the most important parameters in contributing to water quality variations for all three periods. Results of WQIIM revealed that 18 sites were classified as 'meeting standard' while the other 14 sites were classified as 'not meeting standard', with most of the seriously polluted sites located in urban area, mainly due to discharge of wastewater from domestic and industrial sources. Sites with low pollution level were located primarily in smaller tributaries, whereas sites of medium and high pollution levels were in the main river channel and the larger tributaries. Our findings provide valuable information and guidance for water pollution control and water resource management in the Luanhe River Basin. PMID:23508159
Peng, Dingzhi; You, Jinjun
The Hai River basin is one of the three important bread baskets in China. As the rapid economy development in the basin, surface water reduction, groundwater overexploitation and water pollution had caused serious deterioration of the ecological environment. The rainfall, evaporation, surface water, groundwater, water quality, pollution sources, supply and demand of water resources were analyzed and the characteristic of water resources evolution was summarized in Hai River basin. Furthermore, the social and economic development and the relationship between water resources evolution and social development were discussed in the basin. It was found that the human activity is the first impact factor of water cycle in Hai River basin, and the climate change is the second. Finally, the attenuation of water resources in the basin was induced by the two factors together. For sustainable utilization of water resources in the Hai River basin, the unified management and optimal allocation of water resources should be strengthened and promoted.
Su, Buda; Wang, Anqian; Wang, Guojie; Wang, Yanjun; Jiang, Tong
Based on in situ soil moisture and river runoff records in the Tarim River basin, usability of the long term Essential Climate Variable (ECV) soil moisture dataset is validated in the arid climatic region of China. The spatio-temporal variation of soil moisture and its possible influencing factors in the 1988-2013 is also preliminary analyzed in the current paper. Results reveal that the ECV soil moisture can capture the large scale dynamics of regional water cycle quite satisfactorily, showing good agreement with in situ observations in their seasonal and interannual variability. In the period of 1988-2013, the ECV soil moisture shows obvious increasing trends in the northwest and the southwest parts of the Tarim River basin, particularly in spring (March-May) and autumn (September-November). Statistical analysis further suggests that the variations of soil moisture in the Tarim River basin are more controlled by precipitation, and temperature is less effective in controlling of soil moisture variations.
Liu, Wang-Rong; Zhao, Jian-Liang; Liu, You-Sheng; Chen, Zhi-Feng; Yang, Yuan-Yuan; Zhang, Qian-Qian; Ying, Guang-Guo
Nineteen biocides were investigated in the Yangtze River to understand their spatiotemporal distribution, mass loads and ecological risks. Fourteen biocides were detected, with the highest concentrations up to 166 ng/L for DEET in surface water, and 54.3 ng/g dry weight (dw) for triclocarban in sediment. The dominant biocides were DEET and methylparaben, with their detection frequencies of 100% in both phases. An estimate of 152 t/y of 14 biocides was carried by the Yangtze River to the East China Sea. The distribution of biocides in the aquatic environments was significantly correlated to Gross Domestic Product (GDP), total phosphorus (TP) and total nitrogen (TN), suggesting dominant input sources from domestic wastewater of the cities along the river. Risk assessment showed high ecological risks posed by carbendazim in both phases and by triclosan in sediment. Therefore, proper measures should be taken to reduce the input of biocides into the river systems. PMID:25697474
Wei, N.; Qiu, Y.; Gan, H.; Niu, C.; Liu, J.; Gan, Y.; Zhou, N.
Water resource problems, one of the most important environmental and socio-economic issues, have been a common concern worldwide in recent years. Water resource risks are attracting more and more attention from the international community and national governments. Given the current situations of water resources and the water environment, and the characteristics of water resources management and information statistics of China, this paper establishes an index system for water risk assessment in river basins of China based on the index system of water risk assessment proposed by the World Wide Fund For Nature (WWF) and German Investment and Development Co., Ltd (DEG). The new system is more suitable for Chinese national conditions and endorses the international assessment index. A variety of factors are considered to determine the critical values of classification for each index, and the indexes are graded by means of 5-grade and 5-score scales; the weights and calculation methods of some indexes are adjusted, with the remaining indexes adopting the method of WWF. The Weighted Comprehensive Index Summation Process is adopted to calculate the integrated assessment score of the river basin. The method is applied to the Haihe River basin in China. The assessment shows that the method can accurately reflect the water risk level of different river basins. Finally, the paper discusses the continuing problems in water risk assessment and points out the research required to provide a reference for further study in this field.
Chapman, Duane C.
Chapter 1 -- Notes on the Translation and Use of 'A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China' By Duane C. Chapman and Ning Wang Chapter 2 -- A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China By Bolu Yi, Zhishen Liang, Zhitang Yu, Randuan Lin, and Mingjue He Translated by Duane C. Chapman and Ning Wang The document A Study of the Early Development of Grass Carp, Black Carp, Silver Carp, and Bighead Carp in the Yangtze River, China (Chapter 2 of this volume) was translated from the Chinese with the approval and assistance of the living authors of that study. It contains the most detailed description available, and approximately 200 drawings, of the early development of the subject fishes. Chapter 1 provides important instructions on the use of the translation, including a description of the Chinese morphometric conventions, which differ from those used by North American scientists. Chapter 1 also provides the historical context in which Chapter 2 was developed, and information on how the larvae of the subject fishes, which have invaded the Mississippi River basin, may be distinguished from other fishes present in the basin.
Pan, Chang-Gui; Ying, Guang-Guo; Zhao, Jian-Liang; Liu, You-Sheng; Liu, Shuang-Shuang; Du, Jun; Kookana, Rai S
Perfluoroalkyl substances (PFASs) have received great attention from the public and scientific community due to their potential adverse impacts on the ecosystem and human health. We investigated the occurrence and distribution of 16 PFASs from 2 classes of PFASs-perfluoroalkyl carboxylic acids and perfluoroalkane sulfonic acids-in the archived surface sediments of five major rivers (Yellow River, Hai River, Liao River, Zhujiang River, and Dongjiang River) in northern and southern China. The study was also performed during the wet and dry seasons. Perfluorooctanoic acid and perfluorooctane sulfonic acid were the most frequently detected (detection frequency = 100 and 63 %, respectively) in the sediments of the five rivers; the concentrations ranged from 0.08 to 0.99 ng/g dry weight (dw) and were lower than the limit of detection (
Zhang, Shurong; Lu, X X; Sun, Huiguo; Han, Jingtai; Higgitt, David Laurence
Major ion chemistry and dissolved inorganic carbon system (DIC, mainly HCO3(-) and gaseous CO2) in the Luodingjiang River, a mountainous tributary of the Zhujiang (Pearl River), China, were examined based on a seasonal and spatial sampling scheme in 2005. The diverse distribution of lithology and anthropogenic impacts in the river basin provided the basic idea to assess the effects of lithology vs. human activities on water chemistry and carbon biogeochemistry in river systems. Major ions showed great spatial variations, with higher concentrations of total dissolved solids (TDS) and DIC in the regions with carbonate rocks and clastic sedimentary rocks, while lower in the regions with metamorphic sandstones and schists as well as granites. pCO2 at all sampling sites was oversaturated in June, ranging with a factor from 1.6 to 18.8 of the atmospheric concentration, reflecting the enhanced contribution from baseflow and interflow influx as well as in situ oxidation of organic matter. However, in April and December, undersaturated pCO2 was found in some shallow, clean rivers in the upstream regions. delta13C of DIC has a narrow range from -9.07 to -13.59 per thousand, which was more depleted in the regions with metamorphic rocks and granites than in the carbonate regions. Seasonally, it was slightly more depleted in the dry season (December) than in the wet season (June). The results suggested that lithological variability had a dominant control on spatial variations of water chemistry and carbon geochemistry in river systems. Besides, anthropogenic activities, such as agricultural and urban activities and in-stream damming, as well as river physical properties, such as water depth and transparency, also indicated their impacts. The seasonal variations likely reflected the changes of hydrological regime, as well as metabolic processes in the river. PMID:19185905
Liu, Baolin; Zhang, Hong; Xie, Liuwei; Li, Juying; Wang, Xinxuan; Zhao, Liang; Wang, Yanping; Yang, Bo
This study investigated the occurrence of perfluoroalkyl acids (PFAAs) in surface water from 67 sampling sites along rivers of the Pearl River Delta in southern China. Sixteen PFAAs, including perfluoroalkyl carboxylic acids (PFCAs, C5-14, C16 and C18) and perfluoroalkyl sulfonic acids (PFSAs, C4, C6, C8 and C10) were determined by high performance liquid chromatography-negative electrospray ionization-tandem mass spectrometry (HPLC/ESI-MS/MS). Total PFAA concentrations (∑ PFAAs) in the surface water ranged from 1.53 to 33.5 ng·L(-1) with an average of 7.58 ng·L(-1). Perfluorobutane sulfonic acid (PFBS), perfluorooctanoic acid (PFOA), and perfluorooctane sulfonic acid (PFOS) were the three most abundant PFAAs and on average accounted for 28%, 16% and 10% of ∑ PFAAs, respectively. Higher concentrations of ∑ PFAAs were found in the samples collected from Jiangmen section of Xijiang River, Dongguan section of Dongjiang River and the Pearl River flowing the cities which had very well-developed manufacturing industries. PCA model was employed to quantitatively calculate the contributions of extracted sources. Factor 1 (72.48% of the total variance) had high loading for perfluorohexanoic acid (PFHxA), perfluoropentanoic acid (PFPeA), PFBS and PFOS. For factor 2 (10.93% of the total variance), perfluorononanoic acid (PFNA) and perfluoroundecanoic acid (PFUdA) got high loading. The sorption of PFCAs on suspended particulate matter (SPM) increased by approximately 0.1 log units for each additional CF2 moiety and that on sediment was approximately 0.8 log units lower than the SPM logKd values. In addition, the differences in the partition coefficients were influenced by the structure discrepancy of absorbents and influx of fresh river water. These data are essential for modeling the transport and environmental fate of PFAAs. PMID:25889539
Yang, Silin; Zhao, Ning; Zhou, Dequn; Wei, Rong; Yang, Bin; Pan, Bo
The concentration and chemical speciation of arsenic (As) in different environmental matrixes (water, sediment, agricultural soils, and non-agricultural soils) were investigated in the Nanpan River area, the upstream of Pearl River, China. The results did not show any obvious transport of As along the flow direction of the river (from upstream to downstream). Total As concentrations in sediment were significantly different from those in agricultural soil. According to the comparison to quality standards, the As in sediments of the studied area have potential ecological risks and a minority of the sampling sites of agricultural soils in the studied area were polluted with As. As speciations were analyzed using sequential extraction and the percentage of non-residual fraction in sediment predominated over residual fraction. We thus believe that As in the studied area was with low mobility and bioavailability in sediment, agricultural soils, and non-agricultural soils. However, the bioavailability and mobility of As in sediment were higher than in both agricultural and non-agricultural soils, and thus, special attention should be paid for the risk assessment of As in the river in future studies. PMID:26627697
Zhen, Gengchong; Li, Ying; Tong, Yindong; Yang, Lei; Zhu, Yan; Zhang, Wei
Heavy metals are highly persistent in water and have a particular significance in ecotoxicology. Heavy metals loading from the Pearl River are likely to cause significant impacts on the environment in the South China Sea and the West Pacific. In this study, using monthly monitoring data from a water quality monitoring campaign during 2006-2012, the temporal variation and spatial transfer of six heavy metals (lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn), arsenic (As), and mercury (Hg)) in the Pearl River were analyzed, and the heavy metal fluxes into the sea were calculated. During this period, the annual heavy metal loads discharged from the Pearl River into the South China Sea were 5.8 (Hg), 471.7 (Pb), 1524.6 (Cu), 3819.6 (Zn), 43.9 (Cd), and 621.9 (As) tons, respectively. The metal fluxes showed a seasonal variation with the maximum fluxes occurring from June to July. There is a close association between metal fluxes and runoff. The analysis of the heavy metal transfer from the upstream to the downstream revealed that the transfer from the upstream accounted for a major portion of the heavy metals in the Pearl River Delta. Therefore, earlier industry relocation efforts in the Pearl River watershed may have limited effect on the water quality improvement in surrounding areas. It is suggested that watershed-based pollution control measures focusing on wastewater discharge in both upstream and downstream areas should be developed and implemented in the future. PMID:26780062
Xu, H.; Luo, Y.
Understanding the heterogeneity of climate change and its impacts on annual and seasonal discharge, and the difference between mean flow and extreme flow in different climate regions is of utmost importance to successful water management. To quantify the spatial and temporal heterogeneity of climate change impacts on hydrological processes, this study simulated river discharge in the River Huangfuchuan in semi-arid northern China and the River Xiangxi in humid southern China. We assessed the uncertainty in projected discharge for three time periods (2020s, 2050s and 2080s) using seven equally weighted GCMs for the SRES A1B scenario. Climate projections that were applied to semi-distributed hydrological models Soil Water Assessment Tools (SWAT) in both catchments showed trends toward warmer and wetter conditions, particularly for the River Huangfuchuan. Results based on seven GCMs' projections indicated -1.1 to 8.6 and 0.3 to 7.0 °C changes in seasonal temperature and -29 to 139 and -32 to 85 % changes in seasonal precipitation in River Huangfuchuan and River Xiangxi, respectively. The largest increases in temperature and precipitation in both catchments were projected in the spring and winter seasons. The main projected hydrologic impact was a more pronounced increase in annual discharge in the River Huangfuchuan than in the River Xiangxi. Most of the GCMs projected increased discharge in all seasons, especially in spring, although the magnitude of these increases varied between GCMs. Peak flows was projected to appear earlier than usual in River Huangfuchuan and later than usual in River Xiangxi. While the GCMs were fairly consistent in projecting increased extreme flows in both catchments, the increases were of varying magnitude compared to mean flows. For River Huangfuchuan in the 2080s, median flow changed from -2 to 304 %, compared to a -1 to 145 % change in high flow (Q05 exceedence threshold). For River Xiangxi, low flow (Q95 exceedence threshold) changed
Zhang, Peng; Pang, Yong; Pan, Hongche; Shi, Chengchun; Huang, Yawen; Wang, Jianjian
Dissolved oxygen (DO) is not only a fundamental parameter of coastal water quality, but also an indication of organics decomposed in water and their degree of eutrophication. There has been a concern about the deterioration of dissolved oxygen conditions in the Minjiang River Estuary, the longest river in Fujian Province, Southeast China. In this study, the syntheses effects on DO was analyzed by using a four year time series of DO concentration and ancillary parameters (river discharge, water level, and temperature) from the Fuzhou Research Academy of Environmental Sciences, at three automated stations along the Minjiang River Estuary. Hypoxia occurred exclusively in the fluvial sections of the estuary during the high temperature and low river discharge period and was remarkably more serious in the river reach near the large urban area of Fuzhou. Enhancement of respiration by temperature and discharge of domestic sewage and industrial wastewater, versus regeneration of waters and dilution of pollutant concentration with increased river discharge, which regarded as the dominant antagonist processes that controlled the appearance of seasonal hypoxia. During the high temperature and the drought period, minimal mainstream flow above 700 m3·s−1, reduction of pollutants and forbidding sediment dredging in the South Channel should be guaranteed for strong supports on water quality management and drinking water source protection. PMID:26270670
Zhang, Peng; Pang, Yong; Pan, Hongche; Shi, Chengchun; Huang, Yawen; Wang, Jianjian
Dissolved oxygen (DO) is not only a fundamental parameter of coastal water quality, but also an indication of organics decomposed in water and their degree of eutrophication. There has been a concern about the deterioration of dissolved oxygen conditions in the Minjiang River Estuary, the longest river in Fujian Province, Southeast China. In this study, the syntheses effects on DO was analyzed by using a four year time series of DO concentration and ancillary parameters (river discharge, water level, and temperature) from the Fuzhou Research Academy of Environmental Sciences, at three automated stations along the Minjiang River Estuary. Hypoxia occurred exclusively in the fluvial sections of the estuary during the high temperature and low river discharge period and was remarkably more serious in the river reach near the large urban area of Fuzhou. Enhancement of respiration by temperature and discharge of domestic sewage and industrial wastewater, versus regeneration of waters and dilution of pollutant concentration with increased river discharge, which regarded as the dominant antagonist processes that controlled the appearance of seasonal hypoxia. During the high temperature and the drought period, minimal mainstream flow above 700 m(3)s(-1), reduction of pollutants and forbidding sediment dredging in the South Channel should be guaranteed for strong supports on water quality management and drinking water source protection. PMID:26270670
Yu, B.; Xu, L.
Hydropower development can be considered as a kind of trade-offs of ecosystem services generated by human activity for their economic and energy demand, because it can increase some river ecosystem services but decrease others. In this context, an ecosystem service trade-off framework in hydropower development was proposed in this paper. It aims to identify the ecological cost of river ecosystem and serve for the ecological compensation during hydropower development, for the hydropower services cannot completely replace the regulating services of river ecosystem. The valuing trade-offs framework was integrated by the influenced ecosystem services identification and ecosystem services valuation, through ecological monitoring and ecological economic methods, respectively. With a case study of Pondo hydropower project in Tibet, China, the valuing trade-offs of river ecosystem services in large hydropower development was illustrated. The typical ecological factors including water, sediment and soil were analyzed in this study to identify the altered river ecosystem services by Pondo hydropower project. Through the field monitoring and valuation, the results showed that the Lhasa River ecosystem services value could be changed annually by Pondo hydropower project with the increment of 5.7E+8CNY, and decrement of 5.1E+7CNY. The ecological compensation for river ecosystem should be focus on water and soil conservation, reservoir dredging and tributaries habitat protection.
Zhao, L.-N.; Tian, F.-Y.; Wu, H.; Qi, D.; di, J.-Y.; Wang, Z.
The precipitation forecasts of three ensemble prediction systems (EPS) and two multi-model ensemble prediction systems (MM EPS) were assessed by comparing with observations from 19 rain gauge stations located in the Dapoling-Wangjiaba sub-catchment of Huaihe Basin for the period from 1 July to 6 August 2008. The sample Probabilistic Distribution Functions (PDF) of gamma distribution, the Relative Operating Characteristic (ROC) diagrams, the percentile precipitation and a heavy rainfall event are analyzed to evaluate the performances of the single and multi-model ensemble prediction system (EPS). The three EPS were from the China Meteorological Administration (CMA); the United States National Centre for Environment Predictions (NCEP); and the European Centre for Medium-Range Weather Forecasts (ECMWF), all were obtained from the TIGGE-CMA archiving centre (THORPEX Interactive Grand Global Ensemble, TIGGE). The MM EPS were created using the equal weighting method for every ensemble member over the test area, the first ( MM-1) consisted of all three EPS, the second (MM-2) consisted of the ECMWF and NCEP EPS. The results demonstrate the level of correspondence between deterioration in predictive skill and extended lead time. Compared with observations and with a lead time of one day, ECMWF performs a little better than other centre's. With over five days in advance, all the three EPS and the two MM EPS don't give reliable probabilistic precipitation forecasts. Both MM EPS can outperform CMA and NCEP for most of the forecasted days, but still perform a little worse than ECMWF. Though variation of daily percentile precipitation and ROC areas show MM-2 outperforms MM-1, gamma distribution indicates much similar performances for all 10-day forecast, and neither is superior to ECMWF.
Zhao, T. B.; Fu, C. B.
Summer precipitation products from the 45-Year European Centre for Weather Forecast (ECTMWF) Reanalysis (ERA-40), and NCEP-Department of Energy (DOE) Atmospheric Model Intercomparison Project (ATMIP-II) Reanalysis (NCEP-2), and Climatic Research Unit (CRU) TS 2.1 dataset are compared with the corresponding observations over China in order to understand the quality, and utility of the reanalysis datasets for the period 1979-2001. The results reveal that although the magnitude and location of the rainfall belts differ among the reanalysis, CRU, and station data over South and West China, the spatial distributions show good agreement over most areas of China. In comparison with the observations in most areas of China, CRU best matches the observed summer precipitation, while ERA-40 reports less precipitation and NCEP-2 reports more precipitation than the observations. With regard to the amplitude of the interannual variations, CRU is better than either of the reanalyses in representing the corresponding observations. The amplitude in NCEP-2 is stronger but that of ERA-40 is weaker than the observations in most study domains. NCEP-2 has a more obvious interannual variability than ERA-40 or CRU in most areas of East China. Through an Empirical orthogonal function (EOF) analysis, the main features of the rainfall belts produced by CRU aggree better with the observations than with those produced by the reanalyses in the Yangtze-Huaihe River valley. In East of China, particularly in the Yangtze-Huaihe River valley, CRU can reveal the quasi-biennial oscillation of summer precipitation represented by the observations, but the signal of ERA-40 is comparatively weak and not very obvious, whereas that of NCEP-2 is also weak before 1990 but very strong after 1990. The results also suggest that the magnitude of the precipitation difference between ERA-40 and the observations is smaller than that between NCEP-2 and the observations, but the variations represented by NCEP-2 are
The carbon isotopic composition (δ13C) of dissolved and particulate inorganic carbon (DIC; PIC) was used to compare and analyze the origin, dynamics and evolution of inorganic carbon in two headwater tributaries of the Xi River, Southwest China. Carbonate dissolution and soil CO2 were regarded as the primary sources of DIC on the basis of δ13CDIC values which varied along the Nanpan and Beipan Rivers, from −13.9‰ to 8.1‰. Spatial trends in DIC differed between the two rivers (i.e., the tributaries), in part because factors controlling pCO2, which strongly affected carbonate dissolution, differed between the two river basins. Transport of soil CO2 and organic carbon through hydrologic conduits predominately controlled the levels of pCO2 in the Nanpan River. However, pCO2 along the upper reaches of the Nanpan River also was controlled by the extent of urbanization and industrialization relative to agriculture. DIC concentrations in the highly urbanized upper reaches of the Nanpan River were typical higher than in other carbonate-dominated areas of the upper Xi River. Within the Beipan River, the oxidation of organic carbon is the primary process that maintains pCO2 levels. The pCO2 within the Beipan River was more affected by sulfuric acid from coal industries, inputs from a scenic spot, and groundwater than along the Nanpan River. With regards to PIC, the contents and δ13C values in the Nanpan River were generally lower than those in the Beipan River, indicating that chemical and physical weathering contributes more marine carbonate detritus to the PIC along the Beipan River. The CO2 evasion flux from the Nanpan River was higher than that in the Beipan River, and generally higher than along the middle and lower reaches of the Xi River, demonstrating that the Nanpan River is an important net source of atmospheric CO2 in Southwest China. PMID:27513939
The carbon isotopic composition (δ13C) of dissolved and particulate inorganic carbon (DIC; PIC) was used to compare and analyze the origin, dynamics and evolution of inorganic carbon in two headwater tributaries of the Xi River, Southwest China. Carbonate dissolution and soil CO2 were regarded as the primary sources of DIC on the basis of δ13CDIC values which varied along the Nanpan and Beipan Rivers, from -13.9‰ to 8.1‰. Spatial trends in DIC differed between the two rivers (i.e., the tributaries), in part because factors controlling pCO2, which strongly affected carbonate dissolution, differed between the two river basins. Transport of soil CO2 and organic carbon through hydrologic conduits predominately controlled the levels of pCO2 in the Nanpan River. However, pCO2 along the upper reaches of the Nanpan River also was controlled by the extent of urbanization and industrialization relative to agriculture. DIC concentrations in the highly urbanized upper reaches of the Nanpan River were typical higher than in other carbonate-dominated areas of the upper Xi River. Within the Beipan River, the oxidation of organic carbon is the primary process that maintains pCO2 levels. The pCO2 within the Beipan River was more affected by sulfuric acid from coal industries, inputs from a scenic spot, and groundwater than along the Nanpan River. With regards to PIC, the contents and δ13C values in the Nanpan River were generally lower than those in the Beipan River, indicating that chemical and physical weathering contributes more marine carbonate detritus to the PIC along the Beipan River. The CO2 evasion flux from the Nanpan River was higher than that in the Beipan River, and generally higher than along the middle and lower reaches of the Xi River, demonstrating that the Nanpan River is an important net source of atmospheric CO2 in Southwest China. PMID:27513939
Ma, Wan-Li; Liu, Li-Yan; Qi, Hong; Zhang, Zi-Feng; Song, Wei-Wei; Shen, Ji-Min; Chen, Zhong-Lin; Ren, Nan-Qi; Grabuski, Josey; Li, Yi-Fan
The Songhua River is the third largest river in China and the primary source of drinking and irrigation water for northeastern China. The distribution of 16 priority polycyclic aromatic hydrocarbons (PAHs) in water [dissolved water (DW) and suspended particulate matter (SPM)], sediment, and soil in the river basin was investigated, and the associated risk of cancer from these PAHs was also assessed. The total concentration of PAHs ranged from 13.9 to 161 ng L(-1) in DW, 9.21 to 83.1 ng L(-1) in SPM, 20.5 to 632 ng g(-1) dw (dry weight) in sediment, and from 30.1 to 870 ng g(-1) dw in soil. The compositional pattern of PAHs indicated that three-ring PAHs were predominant in DW and SPM samples, while four-ring PAHs dominated in sediment and soil samples. The spatial distribution of PAHs revealed some site-specific sources along the river, with principal component analysis indicating that these were from pyrogenic sources (such as coal and biomass combustion, and vehicle emissions) and coke oven emission distinguished as the main source of PAHs in the Songhua River Basin. Based on the ingestion of PAH-contaminated drinking water from the Songhua River, cancer risk was quantitatively estimated by combining the Incremental Lifetime Cancer Risk assessment model and BaP-equivalent concentration for five age groups of people (adults, teenagers, children, toddlers, and infants). Overall, the results suggest that the estimated integrated lifetime cancer risk for all groups was in acceptable levels. This study is the first attempt to provide information on the cancer risk of PAHs in drinking water from the Songhua River. PMID:23564413
Yan, Ping; Li, XiaoMei; Ma, YuFeng; Wu, Wei; Qian, Yao
Arid regions are affected by long-term interactions between various factors including water and wind. Recent research has concentrated on aeolian-fluvial interactions in dryland environments, including the important role of rivers in providing sand and spaces for deserts development, as well as the influences of aeolian activity upon river landforms. However, there is still a lack of comprehensive data at the large watershed scale to support such research. In this study, we analyzed statistically the morphological parameters related to twelve deserts and ten watersheds in dryland regions of northern China using remote sensing data, maps of desert and watershed distributions, and classification of aeolian landforms. Results indicate that, in view of the relationship between deserts and rivers, the geomorphic structures of drainage basins in northern China can be overall divided into five large drainage zones: northwestern drainage (ND), western drainage (WD), drainage of northern Qinghai-Tibet Plateau (PD), middle drainage (MD) and eastern drainage (ED). In the terms of percent area of desert in drainages, it can be sequenced as WD > MD > ND > ED > PD. For percent area of shifting dunes in deserts, WD > PD > MD > ED > ND. Considering the classification of aeolian dunes, transverse dune dominates in all drainages, and its proportion can be sorted as PD > ED > MD > WD > ND. There is a significant difference in their morphological parameters between interior and exterior watersheds. In exterior watersheds, desert area, shifting dune or transverse dune areas are not significantly associated with drainage area respectively, but interior watersheds have good correlations between them. And in three rivers of Tarim Basin, along with increasing distance from the river bank, the types of aeolian dune (complexity) increased step-wisely, implying that sand dune extends along the river terrace. Those data and preliminary findings confirm that the rivers are indispensable to the
Xu, Jianhua; Chen, Yaning; Bai, Ling; Xu, Yiwen
Fluctuant and complicated hydrological processes can result in the uncertainty of runoff forecasting. Thus, it is necessary to apply the multi-method integrated modeling approaches to simulate runoff. Integrating the ensemble empirical mode decomposition (EEMD), the back-propagation artificial neural network (BPANN) and the nonlinear regression equation, we put forward a hybrid model to simulate the annual runoff (AR) of the Kaidu River in northwest China. We also validate the simulated effects by using the coefficient of determination (R2) and the Akaike information criterion (AIC) based on the observed data from 1960 to 2012 at the Dashankou hydrological station. The average absolute and relative errors show the high simulation accuracy of the hybrid model. R2 and AIC both illustrate that the hybrid model has a much better performance than the single BPANN. The hybrid model and integrated approach elicited by this study can be applied to simulate the annual runoff of similar rivers in northwest China.
Xu, H.; Luo, Y.
Understanding the heterogeneity of climate change and its impacts on annual and seasonal discharge and the difference between median flow and extreme flow in different climate regions is of utmost importance to successful water management. To quantify the spatial and temporal heterogeneity of climate change impacts on hydrological processes, this study simulated river discharge in the River Huangfuchuan in semi-arid northern China and in the River Xiangxi in humid southern China. The study assessed the uncertainty in projected discharge for three time periods (2020s, 2050s and 2080s) using seven equally weighted GCMs (global climate models) for the SRES (Special Reports on Emissions Scenarios) A1B scenario. Climate projections that were applied to semi-distributed hydrological models (Soil Water Assessment Tools, SWAT) in both catchments showed trends toward warmer and wetter conditions, particularly for the River Huangfuchuan. Results based on seven GCMs' projections indicated changes from -1.1 to 8.6 °C and 0.3 to 7.0 °C in seasonal temperature and changes from -29 to 139 % and -32 to 85 % in seasonal precipitation in the rivers Huangfuchuan and Xiangxi, respectively. The largest increases in temperature and precipitation in both catchments were projected in the spring and winter seasons. The main projected hydrologic impact was a more pronounced increase in annual discharge in the River Huangfuchuan than in the River Xiangxi. Most of the GCMs projected increased discharge in all seasons, especially in spring, although the magnitude of these increases varied between GCMs. The peak flows were projected to appear earlier than usual in the River Huangfuchuan and later than usual in the River Xiangxi, while the GCMs were fairly consistent in projecting increased extreme flows in both catchments with varying magnitude compared to median flows. For the River Huangfuchuan in the 2080s, median flow changed from -2 to 304 %, compared to a -1 to 145 % change in high flow
Cheng, Wan-Yen; Lin, Saulwood; Lou, Jiann-Yuh; Wei, Kuo-Yen; Liu, CharShine; Chen, Shing-Li; Wang, Yun-Shuen
Small rivers derived particles are major source of sediment to the ocean in the present time. Small rivers in Taiwan are subjected to fast tectonic activity, high precipitation rate and erosion rate. The combined annual river particle load from small rivers on the Island of Taiwan is higher than that of the Mississippi River. A large fraction of those rivers particle may finding its way into the surrounding seas and ocean, e.g. South China Sea, East China Sea, and the Philippine Sea. Furthermore, due to the nature of particle transportation off rivers from Taiwan were connected by a number of canyon systems close by the river mouth, majority of those river particles were facilitated in delivering and deposited later further into the South China Sea deep basin. The objectives of this study are to understand spatial variations in sedimentation rates and to resolve the temporal differences in sedimentation in the Northeastern South China Sea region, and to evaluate influence of small river particles to the marginal sea. A set of cores was collected in overlying water depth within 1600 - 3300 m for mutilsensor core logging of magnetic susceptibility, density, and porosity. Foraminifera (G. sacculifer, G. conglobatus, O. universa) were picked and AMS C14 analyses for age determination. Grain size, organic carbon, carbonate and biogenic silica content were measured. The results show that large sedimentation rates difference existed in the study area. Earlier studies on sedimentation rate in the region west of our study area were in range of about 10 cm/kyr while our rates are about 20-40 cm/kyr and much higher near Taiwan. Bulk sedimentation rate were higher during the transition period between LGM and Holocene and lower during Holocene. Our results demonstrated that large quantity of particles from small rivers in Taiwan are and were major source of particle and are the dominating factor in controlling sediment deposition in the northeastern South China Sea.
Zhao, Meng; Shao, Lei; Liang, Jianshe; Li, Qianyu
Rare earth elements (REE) in the sediment samples of six industrial wells from the Yinggehai-Song Hong Basin in the Northwestern South China Sea were analyzed and compared with the detrital zircon U-Pb data from earlier studies to extrapolate sediment provenance. The results reveal that the Red River (Song Hong River), Hainan Island and Central Vietnam have been the main provenances of the Yinggehai-Song Hong Basin since the late Oligocene. The Red River has been supplying sediments with positive Eu anomalies from basic-ultrabasic metamorphic and volcanic parent rocks to most parts of the basin, while Hainan Island has delivered sediments with negative Eu anomalies from granitic and sedimentary parent rocks to the eastern slope area of the basin. The progradational downlap structures in the seismic profiles also support the finding that the sediment supply is mainly from the Red River and from Hainan Island. The metamorphic rocks, which are widespread within the Red River drainage, not only provided high volumes of sediments to the basin but also contributed to the positive Eu anomalies observed. Because their REE and U-Pb signatures are similar to those of the Red River source, the metamorphic and igneous rocks of the Song Ma Suture Zone, Kontum Massif, and Jinghong area were probably parts of a large basic provenance region before being separated by strike-slip movements along the Ailao Shan-Red River shear zone. Furthermore, our results indicate that the Red River drainage area has been relatively stable since the late Oligocene. Therefore, if a drainage capture from the Red River occurred, it is likely to have taken place before the late Oligocene.
Zhang, Yongyong; Zhai, Xiaoyan; Shao, Quanxi; Yan, Ziqi
The assessment of flow regime alterations is fundamental in understanding the potential impact of reservoirs and other water infrastructures on aquatic ecosystems and biota. Previously used methods to classify flow regimes have not captured temporal changes between unregulated and regulated flow regimes at individual stations. In this study, a combination of hierarchical classification and trend analysis was used to assess spatial and temporal flow regime alterations in the Huai River Basin, China. Two categories of flow regime indices were selected to characterize the impacts of reservoir and sluice regulation, including the basic flow indices for mean variation, and the cumulative variation indices for long-term alteration. The overall impact of reservoirs and sluices on flow regime included the decrease of high flow magnitudes but the increase of low flow magnitudes through time. Moreover, on average, the flow variability, and the high and low flow frequencies were reduced, while their durations were increased. Reservoirs had a greater impact on flow regimes than sluices. The flow regimes at 18 of 30 stations were altered significantly from a pre-regulation condition and were divided into three main types of alteration corresponding to operational rules of reservoirs and sluices. From a management perspective, water projects in China should address the environmental flow requirements of the rivers, particularly in terms of the hydrologic indices affected mostly by reservoirs and sluices. This study will promote the application of flow regime classification and river restoration in highly regulated basins in China.
Zhu, Jian; Huang, Dan-Qing; Dai, Ying; Chen, Xi
The recent heterogeneous warming and the associated summer precipitation over eastern China are investigated in this study. In 1990-1999, there exist warming over northwestern Pacific and cooling over eastern equatorial Pacific, which can be quantified by temperature gradient index (TGI). Positive and negative cases are chosen based on TGI. In positive cases, a "southern flood and northern drought" summer rainfall pattern dominates over eastern China. The atmospheric circulations show that associated with the southward receding of western Pacific subtropical high (WPSH), ascending motion accompanied with more water vapor exists over southern China. Furthermore, cold-warm air activity affected by weakened East Asian subtropical jet (EASJ) and strengthened East Asia polar front jet (EAPJ) may also be responsible for this rainfall anomaly pattern. In negative cases, significant positive Meiyu-like rainfall anomaly concentrated over Yangtze Huaihe River Basin (YHRB). Associated with the northward shift of WPSH, more water vapor is transported to YHRB. Additionally, the enhanced ascending motion over YHRB may be related with the northward shift of the EAPJ and westward shift of the EASJ. The results reinforce the notion that the configuration of EASJ and EAPJ in both intensity and position has large impacts on the precipitation variations over eastern China.
Gao, C.; Zhu, Q.; Zhao, Z.; Pan, S.; Xu, Y. P.
The impacts of climate change on regional hydrological extreme events have attracted much attention in recent years. This paper aims to provide a general overview of changes on future runoffs and water levels in the Qu River Basin, upper reaches of Qiantang River, East China by combining future climate scenarios, hydrological model and 1D hydraulic model. The outputs of four GCMs BCC, BNU, CanESM and CSIRO under two scenarios RCP4.5 and RCP8.5 for 2021-2050 are chosen to represent future climate change projections. The LARS-WG statistical downscaling method is used to downscale the coarse GCM outputs and generate 50 years of synthetic precipitation and maximum and minimum temperatures to drive the GR4J hydrological model and the 1D hydraulic model for the baseline period 1971-2000 and the future period 2021-2050. Finally the POT (Peaks Over Threshold) method is applied to analyze the change of extreme events in the study area. The results show that design runoffs and water levels all indicate an increasing trend in the future period for Changshangang River, Jiangshangang River and Qu River at most cases, especially for small return periods(≤20), and for Qu River the increase becomes larger, which suggests that the risk of flooding will probably become greater and appropriate adaptation measures need to be taken.
Liu, J.; Zhang, F.; Li, Y.
The Haihe River Basin contains large urban centers and a significant portion of the population of China. The assessment of ecosystem health of urban water systems is the scientific basis for the basin water resources management and ecological restoration. An indicator system was developed for the ecosystem and landscape, which contains three levels. It uses the weighted average fuzzy synthetic evaluation method to assess the health status of urban water systems in order to diagnose the restriction factors of ecosystem health. As a case study in Beijing, the results indicated that the Nanchang River was in a healthy state, the degree of membership belonging to the healthy state was 0.417. In contrast, the Yongding River, the Beihucheng River and the Liangma River were in an unhealthy state; their degrees of membership were 0.585, 0.854 and 0.901 respectively. Much attention should be paid to the urban water systems in the Haihe River Basin, especially for the evaluated systems with an unhealthy state index of over 0.8. These urban water system are very important for the overall integrity of the basin ecosystem.
Chen, Chung-Chi; Shiah, Fuh-Kwo; Chiang, Kuo-Ping; Gong, Gwo-Ching; Kemp, W. Michael
Planktonic communities tend to flourish on the western margins of the East China Sea (ECS) fueled by substrates delivered largely from the Changjiang River, the fifth largest river in the world. To study the effects of the Changjiang River discharge on planktonic community respiration (CR), physical-chemical variables and key processes were measured in three consecutive summers in the ECS. Results showed that concentrations of nitrate and Chl a, protozoan biomass, bacterial production, as well as CR in the surface water were all negatively correlated with sea surface salinity, reflecting the strong influence of river discharge on the ECS shelf ecosystem. Moreover, mean values of nitrate, Chl a concentrations, and CR rates were proportionally related to the area of Changjiang diluted water (CDW; salinity ≤31.0 practical salinity units (psu)), an index of river discharge rate. Presumably, higher river flow delivers higher nutrient concentrations which stimulate phytoplankton growth, which in turn fuels CR. CR exhibited significant monthly and interannual variability, and rates appear to be dominated by bacteria and phytoplankton. Although the plankton community was relatively productive (mean = 0.8 mg C m-2 d-1) in the CDW, the mean ratio of production to respiration was low (0.42). This suggests that the heterotrophic processes regulating CR were supported by riverine organic carbon input in addition to in situ autotrophic production.
Yin, Xiao-min; Lyu, Xian-guo; Liu, Xing-tu; Xue, Zhen-shan
The present study was conducted to evaluate the influence of land use change on dissolved organic carbon (DOC) export in Naoli River watershed, Northeast China. Seasonal variation of DOC concentrations of the river water and its relationship with land use in the whole watershed and 100 m riparian zone at the annual average scale were analyzed using the method of field sampling, laboratory analysis, GIS and statistics analysis. The results showed that the concentrations of DOC under base flow conditions in spring and summer were significantly higher than that in fall in the study watershed. The seasonal trend of DOC concentrations in wetland-watersheds was similar to that in all the sub-watersheds, while significantly different from that in non-wetland watersheds. On the annual average scale, percentage of wetland in the whole watershed and paddy field in the 100 m riparian zone had positive relationship with the DOC concentration in the river water, while percentage of forest in the whole watershed had negative relationship with it (P < 0.05). It indicated that wetland in the sub-watershed played a significant role in the seasonal variation of DOC in river water of Naoli River watershed. Wetland in the watershed and paddy field in the 100 m riparian zone significantly promoted DOC export, while forest alleviated it. Land use change in the watershed in the past few decades dramatically changed the DOC balance of river water. PMID:27112020
DeFu, He; RuiRui, Chen; EnHui, Zhu; Na, Chen; Bo, Yang; HuaHong, Shi; MinSheng, Huang
Following urbanization, a large number of urban rivers were contaminated and turned to black-odor rivers. The traditional approach for detecting water quality is based on chemical or physical analysis. However, biological toxicity of black-odor water has been less addressed. As two typical black-odor rivers, Jiushanwai River (JS) and Shanxia River (SX) are tributaries of Wen-Rui Tang River in Wenzhou (south of China). The eco-safety of the urban rivers was evaluated by bioassay for water toxicity in this study. Ten and 5 sampling sites were respectively set along JS and SX. Water samples were collected monthly from October 2010 to October 2011. The general physical and chemical parameters of river water were monitored. In order to investigate the ecotoxicological effects of black-odor water, the following bioassays were used: (1) Fish acute toxicity test (Danio rerio, comprehensive toxicity), (2) luminescent bacteria bioassay (Qinghaiensis vibrio, toxicity to bacteria), and (3) tropical claw embryo assay (Xenopus tropicalis, embryo toxicity). Biotoxicity of black-odor rivers water was demonstrated by D. rerio, Q. vibrio, and X. tropicalis embryos. Toxicological effects of black-odor water were respectively shown by mortality of zebrafish, and by the relative inhibitory light rate of luminescent bacteria. However, luminescent bacteria were more sensitive to inspect biotoxicity than zebrafish. In X. tropicalis embryos test, toxicological effects of black-odor water were mostly shown by embryos' survival rate and teratogenic rate. Bioassay results showed that toxicity of SX water was higher than that of JS water, especially in summer. Statistical analysis of luminescent bacteria toxicity test showed that biotoxicity of SX and JS was high in summer, but low in winter and spring. The seasonal changes of water toxicity of the black-odor river were positively correlative with changes of water temperature (p < 0.05), and related to pH and ammonium nitrogen of water
Wang, Jing; Chen, Guoneng; Peng, Zhuolun; Grapes, Rodney
A layer of yellow silt is widely distributed in the late Quaternary succession of the Pearl River delta, southeast China. A representative section at Xi Lingang was analyzed using particle size analysis, scanning electron microscope observation, geochemical analysis and OSL dating to determine the characteristics and genesis of the yellow silt. Grain size composition of the yellow silt is homogeneous and comparable to typical north China loess (10-50 μm as "basic grain size group", <5 μm as "secondary grain size group"). Grain size parameters and frequency distribution curves of the yellow silt also indicate an aeolian origin. Aeolian micro-textures with subangular-subrounded grains characterized by dished surface collision pits during wind transportation. Homogeneous major element composition of the yellow silt suggests that the dust has been well mixed and sorted prior to deposition, a typical feature of aeolian origin, but Chemical Index of Alteration values indicate that the yellow silt has suffered intense weathering after deposition. Five OSL dates obtained in this study and other geochronological data indicate that the yellow silt has a Last Glacial Maximum age. The grain size of loess across China becomes finer from northwest to southeast because of increasing transportation distance, and implies that the loess component of the yellow silt in the Pearl River delta area is also derived from a northwest China provenance.
Tao, Hui; Gemmer, Marco; Song, Yudong; Jiang, Tong
During the past 30 years, water ceased to flow in the lower reaches of the Tarim River in northwest China. A project was initiated that aims for ecosystem recovery and rehabilitation by means of transporting water through an open canal to the lower reaches of the Tarim River. In this study, the ecohydrological responses of this rare type project are assessed. Water loss-runoff relationships and an index model for water loss rates and runoff are analyzed. The detected ecohydrological responses of the canal project include that water diversion dominates the dynamics of (1) the groundwater depth and (2) the tempo-spatial variation of riparian vegetation close to the water channel. The relationships between groundwater depth, vegetation coverage, species richness and soil water content are clearly the main factors contributing to the riparian vegetation. Variations of water mineralization are significant, both temporally and spatially, at each sampling station within the lower reaches of the Tarim River. The study provides basic information on water diversion and stream corridor restoration in the lower reaches of the Tarim River. The results show associated mechanisms between riparian vegetation and hydrological variation in arid zone. This lays the theoretical and practical foundation for improving the evaluation system for supplementary water delivery and comprehensive improvement in the Tarim Basin. It also provides information on strengths and weakness in current practices. These are needed for the planning of ecological recovery and rehabilitation of damaged ecosystems in this and other arid areas in western and northern China.
Zhang, Z. S.; Sun, X. J.; Wang, Q. C.; Zheng, D. M.; Zheng, N.
Mercury pollution in the Second Songhua River (SSR) was serious in the last century due to effluent from a chemical corporation. Effects of riverine self-purification on mercury removal were studied by comparing monitoring data of mercury concentrations varieties in water, sediment, and fish in the past, about 30 years. The present work suggested that a river of such a size like the SSR possessed the potential ability to recover from mercury pollution under the condition that mercury sources were cut off, though it needs a very long time, which might be several decades or even a century of years. During the 30 years with no effluent containing mercury input, total mercury (T-Hg) of water and sediment in some typical segments, mostly near the past effluent outlet, had decreased radically but still higher than the background values, though the decrease amplitudes were over 90% compared with that in 1975. T-Hg had decreased by more than 90% in most fishes, but some were still not suitable for consumption. Methylmercury concentrations (MeHg) of water, sediment, and fish were higher or close to the background levels in 2004. In the coming decades, the purification processes in the SSR would be steady and slow for a long period. PMID:20835296
Koukina, Sofia; Lobus, Nikolai; Peresypkin, Valery; Baturin, Gleb; Smurov, Andrey
Major (Al, Fe, Ti, Mg, Ca, Na, K), minor (Mn) and trace (Cr, Ni, Cd, V, Zn, Cu, Pb, Sb, Bi, Sn, Ag, Li, Co, As, Zr, Mo, Hg) elements along with nutrients (TOC, TS, TP) and TIC were first determined in ten surface sediment samples from the Khai River - Nha Trang Bay estuarine system, South China Sea. According to the sediment quality guidelines and reference background values, most of the element contents that were studied were below the threshold levels, while the content of Ag exceeded significantly the hazardous levels in the most of the samples along the river - sea transect. The local anthropogenic and/or environmental sources of Ag within the region need special study. Aluminum and lithium normalization indicated some specific features in the abundance and distribution of the elements along the salinity gradient. The mean grain size of the sediments decreased from the river part to the bay part of the transect. Sedimentary TOC was relatively low (1-2 %) and showed independent distribution along the river - sea transect in relation to the other elements that were studied. Ca, Ba and Sr distribution showed some sporadic enrichment and were largely controlled by the TIC content in sediments. Sedimentary TP, Al, Fe, Mn, Ti, Na, K, Li, Co, Cs, Zn and V varied within the narrow range and tended to increase seaward. These elements are most likely controlled by the accumulation of their fine grained aluminosilicate host minerals and materials at sites determined by hydrodynamic conditions, i. e., in the sea floor depression. TS, As, Sn, Bi, U, Cd and Mo were relatively low in the sediments studied and tended to decrease seaward with the slight elevation in the intermediate part of the transect. These elements can be scavenged by and/or co-precipitated with the dissolved and particulate materials of the river discharge and further deposited on the river - sea geochemical barrier in the course of estuarine sedimentation. The distribution of Ni, Cr, Zr Cu, Pb, Sb, Hg and
Hao, Xuewen; Cao, Yan; Zhang, Lai; Zhang, Yongyong; Liu, Jianguo
Concern is increasing regarding the environmental impact of the high usage rate and intensive release of antibiotics used for human and animal therapy in major urban areas of China. In the present study, regional environmental distribution simulations and risk assessments for 3 commonly used fluoroquinolones in the Wenyu River catchment were conducted using a typical catchment model widely used in Europe. The fluoroquinolone antibiotics investigated (ofloxacin, norfloxacin, and ciprofloxacin) are consumed at high levels for personal health care in China. These antibiotics were simulated in the aquatic environment of the Wenyu River catchment across the Beijing City area for annual average concentrations, with regional predicted environmental concentrations (PECs) of approximately 711 ng/L, 55.3 ng/L, and 22.2 ng/L and local PECs up to 1.8 µg/L, 116 ng/L, and 43 ng/L, respectively. Apart from hydrological conditions, the concentrations of fluoroquinolones were associated closely with the sewage treatment plants (STPs) and their serving population, as well as hospital distributions. The presence of these fluoroquinolones in the catchment area of the present study showed significant characteristics of the occurrence of pharmaceuticals in the aquatic environment in an urban river, with typical "down-the-drain" chemicals. Significantly high concentrations of specific antibiotics indicated non-negligible risks caused by the intensive use in the local aquatic environment in a metropolitan area, particularly ofloxacin in upstream Shahe Reservoir, middle stream and downstream Qing River, and Liangma River to the Ba River segment. Specific treatment measures for these pharmaceuticals and personal care products in STPs are required for such metropolitan areas. PMID:26178666
Xiao, Mingzhong; Zhang, Qiang; Singh, Vijay P.; Chen, Xiaohong
The Huai River basin is one of the major supplier of agricultural products in China, and droughts have critical impacts on agricultural development. Good knowledge of drought behaviors is of great importance in the planning and management of agricultural activities in the Huai River basin. With the copula functions to model the persistence property of drought, the probabilistic seasonal drought forecasting models have been built in the Huai River basin. In this study, droughts were monitored by the Standardized Precipitation Evapotranspiration Index (SPEI) with the time scales of 3, 6, and 9 months, and their composite occurrence probability has been used to forecast the seasonal drought. Results indicated that the uncertainty related to the predicted seasonal drought is larger when more severe droughts occurred in the previous seasons, and the severe drought which occurs in summer and autumn will be more likely to be persistent in the next season while the severe drought in winter and spring will be more likely to be recovered in the subsequent season. Furthermore, given the different drought statuses in the previous season, spatial patterns of the predicted drought events with the largest occurrence probability have also been investigated, and results indicate that the Huai River basin is vulnerable to the extreme drought in most parts of the basin, e.g., the severe drought in winter will be more likely to be persistent in spring in the central part of the southern Huai River basin. Such persistent drought events pose serious challenges for planning and management of agricultural irrigation, then results of the study will be valuable for the planning of crop cultivation or mitigation of the losses caused by drought in the Huai River basin, China.
Cai, Y. M.; Shyu, J. B. H.; Chang, C. P.
The Longmenshan fold-and-thrust belt at the western edge of the Sichuan Basin has long been identified as an active tectonic belt. This has been clearly illustrated by the disastrous Wenchuan and Lushan earthquakes in the recent decade. The two earthquakes, however, have distinctive characters. In the north, the Wenchuan event occurred on major fault zones identified previously. But in the south, the Lushan event was not accompanied by surface ruptures, and the seismogenic structure is still under debate. In order to further understand the neotectonic characteristics of the Lushan earthquake region, we analyzed fluvial terraces, in the hope that such geomorphic features would provide information of active structures of the area. Along the Tianquan River, river terraces are particularly well developed near two cities, Tianquan and Shiyang. Since the terraces appear to be very wide and limited in these two basin-like areas, we suspected that they formed as filled-up lakes. However, after detailed field investigations, we found that underneath these terraces, early Tertiary bedrocks crop out below river sediments that are only several meters thick. This indicates that the Tianquan River has incised into bedrocks. The slope of the terrace surfaces is similar to that of the present-day riverbed, and the river sediments in the terrace outcrops have similar grain size distribution as current riverbed sediments. Therefore, we suggest that the terraces along the Tianquan River are not related to dammed lake, but were produced by tectonic uplift. Combining the age of terrace sediments dated by optically stimulated luminescence (OSL) and detailed topography of the terrace surfaces, we aim to establish a model for the formation mechanism of these two terrace groups. We hope the results of this study would provide more information of neotectonic characteristics of the southwestern Sichuan Basin, as well as future earthquake hazards in this densely populated region.
Wang, H.; Bi, N.; Saito, Y.; Wu, X.; Wang, A.
Construction and operation of large dams in river basins have trapped large volumes of freshwater and sediment, which not only alters the natural seasonal rhythm of river hydrological cycles, but also creates a disconnection between rivers and their deltas. As a result, the water and sediment discharged to the coastal ocean have been greatly reduced, which triggers profound responses in coastal region including delta destruction, accelerated rise of relative sea level and changes in coastal primary production. The Yellow River has been a well documented system with significant impacts of dam regulation. Recent sediment load and freshwater (2002-2012) delivered to the sea have been reduced to 0.16 billion tones per year and 17.9 km3/yr, approximately 13% and 34% of those in 1950s-1960s, a period without significant dam impacts. Dam interception and dam-facilitated water regulation play a dominated role in reducing the flux of water and sediment to the sea, as well as in changing the grain-size composition of sediment. Consequently, the process of estuarine sediment dynamics has changed and the delta has recently been converted into a destructive phase with strong coastal erosion due to insufficient rive sediment supply although the accretion of the active delta lobe was evident because of rapid local deposition of coarsening river sediment around the river mouth. The delta coast erosion has thus become a major source for sediment transport in the Bohai Sea and even to those in the Yellow Sea given the critical role of monsoonal climate on coastal resuspension and coastal currents. Delta erosion and subsidence have therefore accelerated the rate of relative sea-level rise, considerably higher than the global mean, which has put the mega-delta to be at risk. In addition, recent works have identified two peaks of chlorophyll-a within annual cycle in the delta coastal region, one of which is closely associated with the river delivery of nutrients transferred with
Gao, Hongshan; Li, Zongmeng; Pan, Baotian; Liu, Fenliang; Liu, Xiaopeng
As a drainage system located in arid western China, the Shiyang River, combined with considerable fluvial strata and landform information, provides an environmental context within which to investigate fluvial responses to late Quaternary climate change. Sedimentological analysis and optically stimulated luminescence (OSL) dating enabled us to reconstruct the processes and fluvial styles of three sedimentary sequences of the Shagou and Hongshui rivers in the Shiyang drainage system. Our results present a variety of river behaviors during the late Quaternary in these areas. In the upstream Shiyang River, Zhangjiadazhuang (ZJDZ) profile of the Shagou was dominated by aggradation and a meandering channel pattern at 10.6-4.2 ka, while a noticeable channel incision occurred at ~ 4.2 ka followed by lateral channel migration. In the downstream Shiyang River, Datugou (DTG) profile of the Hongshui was an aggrading meandering river from 39.7 to 7.2 ka while channel incision occurred at 7.2 ka. Another downstream profile, Wudunwan (WDW) of the Hongshui was also characterized by aggradation from 22.4 to 4.8 ka; however, its channel pattern shifted from braided to meandering at ~ 13 ka. A discernable downcutting event occurred at ~ 4.8 ka, followed by three channel aggradation and incision episodes prior to 1.8 ka. The last 1.8 ka has been characterized by modern channel and floodplain development. The fluvial processes and styles investigated have a close correlation with late Quaternary climate change in the Shiyang River drainage. During cold phases, the WDW reach was dominated by aggradation with a braided channel pattern. During warm phases, the rivers that we investigated were also characterized by aggradation but with meandering channel patterns. Channel incision events and changes of fluvial style occurred mainly during climate transitions.
Chen, Baohong; Ji, Weidong; Chen, Jinmin; Lin, Cai; Huang, Haining; Huo, Yunlong; Ji, Xianbiao
Water samples were collected at 20 sites on 4 occasions in 2009 (twice in May, and once in both August and November) along the Jiulong River, South China to examine how nutrient inputs from the Jiulong River could affect the nutrient status of the Xiamen Water. Samples were analyzed for nitrite (NO2-N), nitrate (NO3-N), ammonium (NH4-N), phosphate (PO4-P), silicate (SiO3-Si), salinity, and temperature, to determine the nutrient and trophic status of the river. The results indicate that nutrients are derived mainly from river runoff. NO3-N was the main form of DIN in most parts of the river. In addition, NO3-N, DIN, and SiO3-Si behave conservatively. There is a surplus of DIN and SiO3-Si in the river, and PO4-P is a limitation on phytoplankton growth. The concentration of DIN is typically above 0.60 mg/dm3, and higher than 1.00 mg/dm3 in most parts of the river. The concentration of PO4-P is typically above 0.02 mg/dm3, while the concentration of SiO3-Si is higher than 1.00 mg/dm3. Between 2003 and 2008, samples were collected 3 times per year (May, August and November) at 27 sites in the Xiamen Water and analyzed for NO2-N, NO3-N, NH4-N, PO4-P, salinity, and temperature. We discovered that the Jiulong River was the key source of DIN into the Xiamen Water, but not PO4-P, indicating the reason of the N/P molar ratio imbalance in the Xiamen Water. In the future, the effects of high DIN concentrations on the phytoplankton communities and marine ecosystems of the Xiamen Water shall be studied.
Jingjing, F.; Qiang, H.; Shen, C.; Aijun, G.
Dramatic changes in hydrological factors in the Weihe River basin are analysed. These changes have exacerbated ecological problems and caused severe water shortages for agriculture, industries and the human population in the region, but their drivers are uncertain. The Mann-Kendall test, accumulated departure analysis, sequential clustering and the sliding t-test methods were used to identify the causes of changes in precipitation and runoff in the Weihe basin. Change-points were identified in the precipitation and runoff records for all sub-catchments. For runoff, the change in trend was most pronounced during the 1990s, whereas changes in precipitation were more prominent earlier. The results indicate that human activities have had a greater impact than climate change on the hydrology of the Weihe basin. These findings have significant implications for the establishment of effective strategies to counter adverse effects of hydrological changes in the catchment.
Liu, Haiping; Ye, Shaowen; Yang, Xuefeng; Guo, Chuanbo; Zhang, Huijuan; Fan, Liqing; Zhang, Liangsong; Sovan, Lek; Li, Zhongjie
The Niyang River, a main tributary of the Yarlung Zangbo River, is an important and typical plateau river ecosystem in Tibet, China. At present, few studies have focused on its aquatic living resources and river ecology. In this study, the composition, abundance, and diversity of periphytic protozoa were investigated across four seasons from 2008 to 2009 to better understand their spatio-temporal patterns and relationship to the environment. Our investigation shows that periphytic protozoa in the Niyang River contained 15 genera, belonged to Tubulinea, Alveolata, Discosea and Rhizaria, Alveolata possessed most genera, up to nine, with highest share in abundance, exceeding 50%, Difflugia and Glaucoma were dominant genera. Moreover, four diversity indices of periphytic protozoa, including species richness, total abundance, Shannon-Wiener diversity index and Pielou's evenness index, displayed a significant descending trend as the seasons continued, in the order of winter, spring, summer and autumn; with a significant difference existing between winter and summer (or autumn) for Shannon-Wiener diversity index and species richness (P<0.05). Four of these diversity indices also presented a V-shaped pattern between the upper middle course of the Niyang River and the confluence of the Niyang River and Yarlung Zangbo River, with the lowest value occurred in the middle course of the Niyang River. However, no significant variation was found through the Niyang River (P>0.05). In addition, canonical correlation analysis (CCA) shows that the densities of Difflugia, Glaucomais, Enchelydium, Cyphoderia, and Enchelys correlate with water temperature, alkalinity, hardness, pH, and dissolved oxygen, respectively. Lastly, the relationship between periphytic protozoa diversity and the environmental factors of the Niyang River can be predicted using classification and regression trees (CART) annalysis, which suggests that the total abundance and Shannon-Wiener diversity index would be
Xu, Y.; Tian, Y.; Zhang, X.
The extreme high flows in Jinhua River basin under the impact of climate change for the future period 2011-2040 is analyzed in this study. The future projections are obtained through the PRECIS model with a resolution of 50km×50km under emission scenario A1B. The daily precipitation from the regional climate model PRECIS is bias corrected by distribution based scaling method. Afterwards, three lumped hydrological models (GR4J, HBV and Xinanjiang) are used to simulate the daily discharge, driven with both bias corrected and raw precipitation from the PRECIS model for 2011-2040. It is found that for the three hydrological models, the simulated annual maximum discharges are higher by using the raw precipitation from PRECIS than by bias corrected precipitation at any return period. The largest difference reaches 8000 m3/s. Meanwhile, there are differences in the annual maximum discharge derived from hydrological models (see Figure 1). The largest difference between three models is about 3200 m3/s. In most of the time, the GR4J model predicts the highest annual maximum discharge; the lowest is for Xinanjiang and HBV is in between. Compared to date, the flood risk in the future under scenario A1B tends to be larger estimated by GR4J and smaller by Xinanjiang. The HBV model predicts petty much similar results as the present. With different models, the changing range of design discharge for 100 years return period is six times as much as that for 3 years return period, indicating large uncertainty from hydrological models. design discharge versus return periods from the observation, the GR4J model, the HBV model and the Xinanjiang model for the Jinhua River Basin
Tong, Yindong; Zhao, Yue; Zhen, Gengchong; Chi, Jie; Liu, Xianhua; Lu, Yiren; Wang, Xuejun; Yao, Ruihua; Chen, Junyue; Zhang, Wei
Based on monthly monitoring data of unfiltered water, the nutrient discharges of the eight main rivers flowing into the coastal waters of China were calculated from 2006 to 2012. In 2012, the total load of NH3-N (calculated in nitrogen), total nitrogen (TN, calculated in nitrogen) and total phosphorus (TP, calculated in phosphorus) was 5.1 × 105, 3.1 × 106 and 2.8 × 105 tons, respectively, while in 2006, the nutrient load was 7.4 × 105, 2.2 × 106 and 1.6 × 105 tons, respectively. The nutrient loading from the eight major rivers into the coastal waters peaked in summer and autumn, probably due to the large water discharge in the wet season. The Yangtze River was the largest riverine nutrient source for the coastal waters, contributing 48% of the NH3-N discharges, 66% of the TN discharges and 84% of the TP discharges of the eight major rivers in 2012. The East China Sea received the majority of the nutrient discharges, i.e. 50% of NH3-N (2.7 × 105 tons), 70% of TN (2.2 × 106 tons) and 87% of TP (2.5 × 105 tons) in 2012. The riverine discharge of TN into the Yellow Sea and Bohai Sea was lower than that from the direct atmospheric deposition, while for the East China Sea, the riverine TN input was larger. PMID:26582206
Wang, Ji-Zhong; Guan, Yu-Feng; Ni, Hong-Gang; Luo, Xian-Lin; Zeng, Eddy Y
On the basis of a monthly sampling effort from March 2005 to February 2006, the total concentrations of the sums of 27 and 15 polycyclic aromatic hydrocarbons (defined as sigma27PAHs and sigma15PAHs, respectively) in riverine runoff of the Pearl River Delta (PRD), China, and associated fluxes were determined. No clear temporal and spatial trends of PAH concentrations were found at all eight riverine runoff outlets where the samples were collected. The annual fluxes of sigma27PAHs and sigma15PAHs from the PRD to the coastal ocean were 60.2 and 33.9 metric tons, respectively. Assuming that riverine flux was positively related to the regional emission of PAHs, the annual riverine fluxes from five major rivers in China to the global oceans were estimated, which are quite significant relative to other major rivers of the world. On the basis of mass balance considerations, approximately 87% of sigma15PAHs inputting to the Pearl River Estuary and northern South China Sea was derived from riverine runoff from the PRD. In addition, approcimately 22.3 metric tons of sigma15PAHs annually outflow to open seas, which is equivalent to a concentration of 0.34 pg/L in the global oceans if the PAHs are evenly distributed in the upper 200 m of the water column. A comparison with the global background level of PAHs indicated that approximately 0.4% of PAHs in the open oceans may have been contributed by 1-year discharge from the PRD. PMID:17874763
Background The West Liao River valley in Northeast China is an ecologically diverse region, populated in prehistory by human populations with a wide range of cultures and modes of subsistence. To help understand the human evolutionary history of this region, we performed Y chromosome analyses on ancient human remains from archaeological sites ranging in age from 6500 to 2700 BP. Results 47 of the 70 individuals provided reproducible results. They were assigned into five different Y sub-haplogroups using diagnostic single nucleotide polymorphisms, namely N1 (xN1a, N1c), N1c, C/C3e, O3a (O3a3) and O3a3c. We also used 17 Y short tandem repeat loci in the non-recombining portion of the Y chromosome. There appears to be significant genetic differences between populations of the West Liao River valley and adjacent cultural complexes in the prehistoric period, and these prehistoric populations were shown to carry similar haplotypes as present-day Northeast Asians, but at markedly different frequencies. Conclusion Our results suggest that the prehistoric cultural transitions were associated with immigration from the Yellow River valley and the northern steppe into the West Liao River valley. They reveal the temporal continuity of Y chromosome lineages in populations of the West Liao River valley over 5000 years, with a concurrent increase in lineage diversity caused by an influx of immigrants from other populations. PMID:24079706
Rong, Nan; Shan, Baoqing
Sediment oxygen demand (SOD) is a critical dissolved oxygen (DO) sink in many rivers. Understanding the relative contributions of the biological and chemical components of SOD would improve our knowledge of the potential environmental harm SOD could cause and allow appropriate management systems to be developed. A various inhibitors addition technique was conducted to measure the total, chemical, and biological SOD of sediment samples from 13 sites in the Ziya River watershed, a severely polluted and anoxic river system in the north of China. The results showed that the major component of SOD was chemical SOD due to iron predominate. The ferrous SOD accounted for 21.6-78.9 % of the total SOD and 33.26-96.79 % of the chemical SOD. Biological SOD represented 41.13 % of the overall SOD averagely. Sulfide SOD accounted for 1.78-45.71 % of the total SOD and it was the secondary predominate of the chemical SOD. Manganous SOD accounted for 1.2-16.6 % of the total SOD and it was insignificant at many sites. Only four kinds of benthos were collected in the Ziya River watershed, resulting from the low DO concentration in the sediment surface due to SOD. This study would be helpful for understanding and preventing the potential sediment oxygen depletion during river restoration. PMID:27026547
Wang, Ce; Cyterski, Mike; Feng, Yujie; Gao, Peng; Sun, Qingfang
To control source pollution and improve water quality, an understanding of the spatiotemporal characteristics of organic contaminant concentrations in affected receiving waters is necessary. The Songhua River in northeast China is the country's third-largest domestic river and loadings of organic contaminants along an industrialized section have made it the focal point of a national pollution reduction plan. In addition to water quality issues, management of the Songhua River basin must also address local economic development, aquatic ecosystem sustainability and political relationships with Russia. In three periods spanning 2006 to 2010, eight polycyclic aromatic hydrocarbons (PAHs) and eight phenols were measured in surface waters at ten monitoring sites along the river. A generalized linear model (GLM) was used to characterize water quality at different sites and time periods. Chemical concentrations of the organic compounds showed significant sinusoidal seasonal patterns and the concentrations declined significantly from 2006 to 2010, possibly due to management practices designed to control water pollution. A critical body residue analysis showed that water concentrations measured during the winter of 2007 across all monitoring sites, but especially at S1-Shaokou and S2-Songhuajiangcun, presented a high risk for fish species. The spatiotemporal characteristics of water quality and estimated ecological risks shown here add to the body of knowledge to develop policies on industrial output and pollution management strategies for the Songhua River basin. PMID:26442573
Wang, Y; Bian, J M; Wang, S N; Nie, S Y
The source area of the Liao River is an important grain growing area in China which experiences serious problems with agricultural nonpoint source pollution (NPS) which is impacting the regional economy and society. In order to address the water quality issues it is necessary to understand the spatial distribution of NPS in the Liao River source area. This issue has been investigated by coupling a wavelet artificial neural network (WA-ANN) precipitation model with a soil and water assessment tool (SWAT) model to assess the export of nonpoint source pollutants from the Liao River source area. The calibration and validation of these models are outlined. The WA-ANN models and the SWAT model were run to generate the spatial distribution of nonpoint source nutrient (nitrogen and phosphorus) exports in the source area of the Liao River. It was found that the SWAT model identified the sub-catchments which not only receive high rainfall but are also densely populated with high agricultural production from dry fields and paddy fields, which are large users of pesticides and chemical fertilizer, as the primary source areas for nutrient exports. It is also concluded that the coupled WA-ANN models and the SWAT model provide a tool which will inform the identification of NPS issues and will facilitate the identification of management practices to improve the water environments in the source area of the Liao River. PMID:27533862
Tang, Wenzhong; Cui, Jingguo; Shan, Baoqing; Wang, Chao; Zhang, Wenqiang
The Hai River Basin (HRB) is one of the most polluted river basins in China. The basin suffers from various types of pollutants including heavy metals and nutrients due to a high population density and rapid economic development in this area. We assessed the relationship between heavy metal accumulation by periphyton playing an important role in fluvial food webs and eutrophication in the HRB. The concentrations of the unicellular diatoms (type A), filamentous algae with diatoms (type B), and filamentous algae (type C) varied along the river, with type A dominating upstream, and types B then C increasing in concentration further downstream, and this was consistent with changes in the trophic status of the river. The mean heavy metal concentrations in the type A, B and C organisms were Cr: 18, 18 and 24 mg/kg, respectively, Ni: 9.2, 10 and 12 mg/kg, respectively, Cu: 8.4, 19 and 29 mg/kg, respectively, and Pb: 11, 9.8 and 7.1 mg/kg respectively. The bioconcentration factors showed that the abilities of the organisms to accumulate Cr, Ni and Pb decreased in the order type A, type B, then type C, but their abilities to accumulate Cu increased in that order. The Ni concentration was a good predictor of Cr, Cu and Pb accumulation by all three periphyton types. Our study shows that heavy metal accumulation by periphyton is associated with eutrophication in the rivers in the HRB. PMID:24482681
Yu, Na; Li, Erchao; Feng, Dexiang; Xiao, Baicai; Wei, Chaoqun; Zhang, Meiling; Chen, Liqiao
Most urban rivers play an important role in urban flood control and drainage in China, but pollution is fast becoming an issue of greater importance in water management. In this study, 63 zooplankton species were recorded in four downtown rivers in Shanghai between November 2007 and October 2008. Of these, 44 species belonged to the Rotifera, 13 to Cladocera, and six to Copepoda. The three most frequently occurring zooplankton ( Brachionus calyciflorus, Microcyclops leuckarti, and Asplanchna priodonta) accounted for 80.00%, 76.84%, and 53.68%, respectively. Rotifera were found to be dominant, comprising 86.26% of total zooplankton, while cladoceran and copepod abundance amounted to 5.08% and 8.67%, respectively. Water temperature, salinity, electrical conductivity, and total nitrogen were of the greatest significance in the occurrence of zooplankton. Two species ( Schmackeria forbesi and Lepadella ovalis) were notably more sensitive to environmental factors such as salinity and electrical conductivity than other species. The population size and community were inversely correlated with the increasing nutrient levels of the four rivers, suggesting that the water quality of the four rivers had been gradually recovering from a severe eutrophic state and that water conditions of the rivers had been gradually improved.
Sun, Daolin; Yu, Jianwei; An, Wei; Yang, Min; Chen, Guoguang; Zhang, Shujun
There are regular problems of musty odor in the Huangpu River, a major source of drinking water for Shanghai, China. In this study, the musty odor and its main causative compounds in the Huangpu River source water were confirmed through a yearly investigation using flavor profile analysis combined with HSPME-GC-MS analysis. The investigation showed that 2-methylisoborneol (2-MIB) with a concentration level between 28.6 and 71.0 ng/L was responsible for the musty odor in summer from July to September. Microscopic observation confirmed with the cloning results showed that Phormidium spp., which accounted for 80%-95% of the algal cell density, was the microorganisms responsible for the production of 2-MIB and the estimated 2-MIB yield was 0.022 pg/cell. Results from a wide-area sampling campaign in the Huangpu River watershed showed that, other than the large tributaries receiving water from Tai Lake, several small creeks close to the intake may have contributed most of the 2-MIB and the Phormidium spp. to the Huangpu River source water. This study provides methodology for the investigation of odor causing compounds and microorganisms in river-type source water, and the result will be useful for water quality control in both source water and drinking water. PMID:23923417
Pang, Aiping; Sun, Tao; Yang, Zhifeng
SummaryAgriculture and ecosystems are increasingly competing for water. We propose an approach to assess the economic compensation standard required to release water from agricultural use to ecosystems while taking into account seasonal variability in river flow. First, we defined agricultural water shortage as the difference in water volume between agricultural demands and actual supply after maintaining environmental flows for ecosystems. Second, we developed a production loss model to establish the relationship between production losses and agricultural water shortages in view of seasonal variation in river discharge. Finally, we estimated the appropriate economic compensation for different irrigation stakeholders based on crop prices and production losses. A case study in the Yellow River Estuary, China, demonstrated that relatively stable economic compensation for irrigation processes can be defined based on the developed model, taking into account seasonal variations in river discharge and different levels of environmental flow. Annual economic compensation is not directly related to annual water shortage because of the temporal variability in river flow rate and environmental flow. Crops that have stable planting areas to guarantee food security should be selected as indicator crops in economic compensation assessments in the important grain production zone. Economic compensation may be implemented by creating funds to update water-saving measures in agricultural facilities.
Meng, Qingpeng; Zhang, Jing; Zhang, Zhaoyu; Wu, Tairan
Dissolved trace elements and heavy metals in the Dan River drainage basin, which is the drinking water source area of South-to-North Water Transfer Project (China), affect large numbers of people and should therefore be carefully monitored. To investigate the distribution, sources, and quality of river water, this study integrating catchment geology and multivariate statistical techniques was carried out in the Dan River drainage from 99 river water samples collected in 2013. The distribution of trace metal concentrations in the Dan River drainage was similar to that in the Danjiangkou Reservoir, indicating that the reservoir was significantly affected by the Dan River drainage. Moreover, our results suggested that As, Sb, Cd, Mn, and Ni were the major pollutants. We revealed extremely high concentrations of As and Sb in the Laoguan River, Cd in the Qingyou River, Mn, Ni, and Cd in the Yinhua River, As and Sb in the Laojun River, and Sb in the Dan River. According to the water quality index, water in the Dan River drainage was suitable for drinking; however, an exposure risk assessment model suggests that As and Sb in the Laojun and Laoguan rivers could pose a high risk to humans in terms of adverse health and potential non-carcinogenic effects. PMID:26782327
Zhang, Gao-sheng; Wang, Ren-qing; Song, Bai-min
Data were collected in different successional stages using a simultaneous sampling method and analyzed through quantitative classification method. Three large groups and 12 classes were made to represent the community patterns of three succession stages and 12 succession communities. The succession series of plant community in the study area was as follows: saline bare land-->community Suaeda salsa-->community Tamarix chinensis-->grassland. Succession degree and succession process of 12 succession communities were calculated. Most of these communities were in the lower succession stage, however, community Phragmites communis+Glycine soja and community Imperata cylindrica+G. soja were close to the succession stage of grassland climax. Five species diversity indices were used to study the changes in species richness, species evenness and diversity during succession of community. Heterogeneity index and richness index increased gradually during the community succession process, but species evenness tended to decrease with succession development. The relation between succession and environment was studied by ordination technique, and the results showed that the soil salt content was an important factor to halarch succession of the modern Yellow River Delta. It affected community structure, species composition and succession process. PMID:17657854
Zhang, Gao-sheng; Wang, Ren-qing; Song, Bai-min
Data were collected in different successional stages using a simultaneous sampling method and analyzed through quantitative classification method. Three large groups and 12 classes were made to represent the community patterns of three succession stages and 12 succession communities. The succession series of plant community in the study area was as follows: saline bare land→community Suaeda salsa→community Tamarix chinensis→grassland. Succession degree and succession process of 12 succession communities were calculated. Most of these communities were in the lower succession stage, however, community Phragmites communis+Glycine soja and community Imperata cylindrica+G. soja were close to the succession stage of grassland climax. Five species diversity indices were used to study the changes in species richness, species evenness and diversity during succession of community. Heterogeneity index and richness index increased gradually during the community succession process, but species evenness tended to decrease with succession development. The relation between succession and environment was studied by ordination technique, and the results showed that the soil salt content was an important factor to halarch succession of the modern Yellow River Delta. It affected community structure, species composition and succession process. PMID:17657854
Wang, Huiliang; Li, Xuyong; Xie, Ying
In the context of rapid economic growth in China, hydrochemical characteristics of stream water quality are being influenced by a variety of natural and anthropogenic inputs. We determined 10 hydrochemical parameters of the surface water at 29 monitoring sites in the Luan River basin of northern China during 2007-2009. Water quality hydrochemistry was evaluated using fuzzy comprehensive analysis based on the National Surface Water Environmental Quality Standards of China. Our results showed that 14 sites were classified as 'meeting standard (MS)' while the other 15 sites were classified 'non-meeting standard (NS)'. According to principal component analysis, four potential pollution sources were identified that explained 80.6% of the total variance among these MS sites, and three potential pollution sources that explained 78.3% of the total variance among these NS sites. Furthermore, multi-linear regression of the absolute principal component scores was used to estimate contributions from identified pollution sources. Most water pollution variables were influenced primarily by municipal sewage and non-point pollution in MS sites. In NS sites, chemical industry wastewater pollution dominated. Pollution in the main stream was more serious than that in the small tributaries. Our findings provide useful information for developing better pollution control strategies for the Luan River. PMID:22105137
Zhang, Haibo; Luo, Yongming; Teng, Ying; Wan, Hongfu
Polychlorinated biphenyls (PCBs) contamination in tropical and sub-tropical areas and the associated risks have attracted great concern. A total of 69 samples representing five distinct land types were collected to assess PCB concentrations in the Pearl River Delta (PRD), South China, including spatial distributions in soils of the area, the probable anthropogenic sources, and related potential risks. PCBs concentrations in soils of the PRD ranged from 0.3 to 202 ng g(-1). More severe PCBs contamination was presented in the western part than in the eastern part of the PRD region. The PCBs were dominated by low-chlorinated biphenyls; however, the proportion of higher-chlorinated biphenyls was elevated with the influence of industrial activities. Principal component analysis indicated that PCBs contamination in soils of the PRD region was mainly associated with 1#PCBs, while 2#PCB and e-waste emission in South China also accounted for it partly, especially to the industrial activity severely impacted areas. Toxic equivalent (TEQ) of the dioxin-like PCBs in the soils indicated that higher risk of PCB contamination was presented in the Dongjiang River Valley (55 ng TEQ kg(-1), on average) than in the Xijiang River Valley, and were mostly contributed by the congener of PCB126. PMID:23354616
Zhang, Zhao-yong; Abuduwaili, Jilili; Jiang, Feng-qing
This paper focuses on the sources, pollution status and potential ecology risks of heavy metals (Cr, Cu, Hg, As, Cd, Pb, and Zn) in the surface water, top sediment of river bed and soil along banks of Bortala River, which locates in the oasis region of Xinjiang, northwest China. Results showed that: (1) As a whole, contents of 7 tested heavy metals of Bortala River were low, while the maximum values of Hg, Cd, Pb, and Cr in the river water were significantly higher than those of Secondary Category of the Surface Water Quality Standards of People's Republic of China (GB 3838-2002) and Drinking Water Guideline from WHO. Analysis showed that the heavy metals contents of top sediment on river bed and soils along river banks were significantly higher than those of the river water. (Correlation analysis and enrichment factor (EF) calculation showed that in the river water, top sediment on river bed and soils along river banks, Hg, Cd, Pb, and Cr mainly originated from industrial emissions, urban and rural anthropogenic activities, transportation and agricultural production activities; While Cu, Zn, and As mainly originated from natural geological background and soil parent materials. (3) Pollution assessment showed that in three matrices, the single factor pollution index(Pi) and the integrated pollution index (Pz) of 7 heavy metals were all lower than 1, and they all belonged to safe and clean levels. (4) Potential ecology risk evaluation showed that as a whole the single factor potential ecological risk (Eir) and the integrated potential ecology risks (RI) of 7 heavy metals were relatively low, and would not cause threats to the health of water and soil environment of river basin, while the potential ecology risks of Cd, Hg, Pb, and Cr were significantly higher than those of other heavy metals. PMID:26489307
Chen, Yaning; Xu, Changchun; Chen, Yapeng; Liu, Yongbo; Li, Weihong
Eco-hydrological research in arid inland river basins has been a focus of geologists and ecologists as it is crucial for maintaining the sustainable development of socio-economy, particularly in ecologically vulnerable areas. Based on the research work carried out in the Tarim River basin of Xinjiang, northwestern China, this paper summarizes synthetically the climate change and associated responses of water resources in the mountainous area, land use and land cover in the oasis, and plants responding to environmental stresses in the desert area of the river basin. Research gaps, challenges, and future perspectives in the eco-hydrological studies of the Tarim River basin are also discussed. PMID:22392285
Su, Tao; Feng, Taichen; Feng, Guolin
With the motivation to identify actual evapotranspiration (AE) variability under climate warming over China, an assessment is made from five sets of reanalysis data sets [National Centers for Environmental Prediction-National Center for Atmospheric Research (NCEP-NCAR), NCEP-Department of Energy (NCEP-DOE), Modern-Era Retrospective Analysis for Research and Applications (MERRA), Interim Reanalysis, and Japanese 55-year Reanalysis (JRA-55)]. Based on comparison with AE estimates calculated using the Budyko equation, all five reanalysis data sets reasonably reproduce the spatial patterns of AE over China, with a clearly southeast-northwest gradient. Overall, JRA-55 (NCEP-DOE) gives the lowest (highest) reanalysis evaporation (RE) values. From 1979 to 2013, dominant modes of RE among five reanalyses are extracted using multivariate empirical orthogonal function analysis. Accordingly, the interdecadal variation of RE is likely driven by the change of temperature, and the interannual variation is constrained by the water supply conditions. Under climate warming, RE increase in the Northwest China, Yangtze-Huaihe river basin, and South China, while they decrease in Qinghai-Tibet Plateau, and northern and Northeast China. Moreover, the relationship between RE and pan evaporation (PE) are comprehensively evaluated in space-time. Negative correlations are generally confirmed in nonhumid environments, while positive correlations exist in the humid regions. Our analysis supports the interpretation that the relationship between PE and AE was complementary with water control and proportional with energy control. In view of data availability, important differences in spatial variability and the amount of RE can be found in Northwest China, the Qinghai-Tibet Plateau, and the Yangtze River Basin. Generally speaking, NCEP-NCAR and MERRA have substantial problems on describing the long-term change of RE; however, there are some inaccuracies in the JRA-55 estimates when focusing on
Chen, X.; Zhao, J.; Chen, L.; Tao, X.; Zhao, Z.
Understanding heat fluxes through hyporheic zones (HZ) becomes increasingly important as anthropogenic influences and changing climate alter river thermal regimes. The HZ directly interacts with river thermal regimes by storing and releasing heat over a range of timescales. Alteration of HZ can lead to shifts in aquatic species composition and changes in biogeochemical processes. In this study we examine a reach of the Xinanjiang, China downstream of the Xinanjiang Dam. The Xinanjiang Dam introduces a low temperature water (LTW) region to the downstream of a length of 23 km and an area of 9.9 km2, which greatly changes the downstream thermal regime. However, how and to what extent the LTW in stream affect the HZ temperature distribution and, ulteriorly, the full range of the river ecosystem are still not completely understood. We quantify hyporheic exchange and heat transport induced by LTW by field experiments and numerical simulations for coupled groundwater flow and heat transport. Both surface and subsurface water temperature are measured in a study region for model validation. The hydraulic head and water temperature along the water-aquifer interface are considered as the input boundaries for groundwater models. The upwelling water with short streamline paths shows the same temperature pattern as surface water but the temperature of water that comes out from the deep subsurface zones rises much higher and shows a relatively lower variation. However, with the continuing exchange of surface LTW and groundwater, the low temperature spreads over the entire domain. Detailed field characterization and groundwater modeling indicate residence times of hyporheic flux can vary from hours to months. A significant implication is that the LTW released from upstream reservoir contributes to the downstream temperature field and potential degradation of habitats in hyporheic zones.
Yang, Xin; Gasser, Robin B; Fang, Rui; Zeng, Jinrong; Zhu, Kaixiang; Qi, Mingwei; Zhang, Zongze; Tan, Li; Lei, Weiqiang; Zhou, Yanqin; Zhao, Junlong; Hu, Min
Diseases caused by parasitic helminths cause considerable production and economic losses in livestock worldwide. Understanding the epidemiology of these parasites has important implications for controlling them. The main purpose of the present study was to estimate the prevalence of key parasitic helminths in goats along the Han River in Zhanggang, Hubei Province (from January to December 2014). We used faecal flotation and sedimentation techniques as well as PCR-based DNA sequencing to detect and identify helminths. Results showed that the prevalence of helminths was high throughout the year, particularly for gastrointestinal nematodes. These first findings provide useful baseline information for goat helminths in Zhanggang, and a starting point for the implementation of control programs. With an increased expansion of the goat industry in China, the findings also emphasise the need to undertake prevalence surveys in other regions of China where extensive farming practices are used. PMID:27447226
Xiao, Rong; Bai, Junhong; Huang, Laibin; Zhang, Honggang; Cui, Baoshan; Liu, Xinhui
Sediments were collected from the upper, middle and lower reaches of both urban and rural rivers in a typical urbanization zone of the Pearl River delta. Six heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) were analyzed in all sediment samples, and their spatial distribution, pollution levels, toxicity and ecological risk levels were evaluated to compare the characteristics of heavy metal pollution between the two rivers. Our results indicated that the total contents of the six metals in all samples exceeded the soil background value in Guangdong province. Based on the soil quality thresholds of the China SEPA, Cd levels at all sites exceeded class III criteria, and other metals exhibited pollution levels exceeding class II or III criteria at both river sites. According to the sediment quality guidelines of the US EPA, all samples were moderately to heavily polluted by Cr, Cu, Ni, Pb and Zn. Compared to rural river sites, urban river sites exhibited heavier pollution. Almost all sediment samples from both rivers exhibited moderate to serious toxicity to the environment, with higher contributions from Cr and Ni. A "hot area" of heavy metal pollution being observed in the upper and middle reaches of the urban river area, whereas a "hot spot" was identified at a specific site in the middle reach of the rural river. Contrary metal distribution patterns were also observed along typical sediment profiles from urban and rural rivers. However, the potential ecological risk indices of rural river sediments in this study were equal to those of urban river sediments, implying that the ecological health issues of the rivers in the undeveloped rural area should also be addressed. Sediment organic matter and grain size might be important factors influencing the distribution profiles of these heavy metals. PMID:24135865
Chen, Ya-ning; Li, Wei-hong; Xu, Chang-chun; Hao, Xin-ming
Based on hydrology, temperature, and precipitation data from the past 50 years, the effects of climate change on water resources in Tarim River Basin in Northwest China were investigated. The long-term trends of the hydrological time series were detected using both parametric and nonparametric techniques. The results showed that the increasing tendency of the temperature has a 5% level of significance, and the temperature increased by nearly 1 degree C over the past 50 years. The precipitation showed a significant increase in the 1980s and 1990s, and the average annual precipitation exhibited an increasing trend with a magnitude of 6.8 mm per decade. A step change occurred in both the temperature and precipitation time series around 1986. The streamflow from the headwater of the Tarim River exhibited a significant increase during the last 20 years. The increase in temperature, precipitation, and streamflow may be attributed to global climate change. PMID:17915714
Chi Yukun; Xu Shice )
The Pearl River Mouth basin is a large Cenozoic continental margin basin that is rich in hydrocarbon potential. Fluvial-lake sequences were deposited before Oligocene, but all were covered by Miocene marine clastic and carbonate rocks. Both paleo-Pearl River delta system and reef/bank carbonate system were widely developed. At the early stage of the evolution, two subsidence belts and one uplift between them distributed in NE regional direction; grabens occurred in the north belt and depressions in the south belt. Tectonic movement was stronger in the east than the west. The main production zones have been drilled both in Miocene sandstone and carbonate rocks. As the exploration activities are developing, the basin will be one of the most significant China offshore oil production areas.
Geng, Junjie; Wang, Yiping; Luo, Hanjin
Riverine samples were collected at various locations in the Pearl River Delta (PRD) to determine the concentrations of heavy metals (Cr, Ni, Cu, Mn, Zn, Cd, and Pb) in time and space and to estimate the fluxes of heavy metals to the coastal waters off South China. Most of the elements exhibit clear temporal and spatial trends. Principal component analysis shows that surface erosion is the major factor affecting metal concentrations in particulates in the PRD. Natural geology is an important source of these heavy metals. The annual fluxes of Cr, Ni, Cu, Mn, Zn, Cd, and Pb in upstream and downstream were 445, 256, 241, 3293, 1279, 12, and 317 t/year and 1823, 1144, 1786, 15,634, 6183, 74, and 2017 t/year, respectively. A comparison indicated that the annual fluxes of Mn accounted for 1.3% of the global river fluxes, whereas other elements contribute <1%. PMID:26555797
He, Xianqiang; Xu, Dongfeng; Bai, Yan; Pan, Delu; Chen, Chen-Tung Arthur; Chen, Xiaoyan; Gong, Fang
The South China Sea (SCS) is the world's largest tropical marginal sea with an oligotrophic basin. In June 2015, a rare large phytoplankton bloom, which is ~500 km long, 100 km wide and lasting more than 19 days, was captured in the northern SCS basin by satellite daily chlorophyll images. Water within the bloom area had a feature of low salinity and high temperature measured by an accidental-passing cruise. Meanwhile, satellite sea level anomaly images and drifter trajectory proved there was a cyclonic eddy nearby. No typhoon and heavy rain happened in this period, so we believed the bloom was triggered by the injection of nutrient-rich Pearl River plume driven by eddy. This is the first report on eddy-entrained Pearl River plume into the SCS, which would raise a new view on irregular transportation of nutrient and carbon and its related biogeochemical influence on the oligotrophic ocean.
Lu, Binyu; Feng, Yujie; Gao, Peng; Zhang, Zhaohan; Lin, Nan
Contamination levels and spatial and temporal distributions of six typical synthetic musks (SMs) in water and sediment of the Songhua River in Northeastern China were investigated. Experimental data for 72 water and 52 sediment samples collected at 29 sampling sites over 12 months spanning 2011-2012 showed that the Songhua River had been contaminated to different degrees at various sites separately from the river's source. The polycyclic musks 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-(g)-2-benzopyran (HHCB) (Galaxolide) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (AHTN) (Tonalide) were found most frequently and at the highest levels. Concentrations of HHCB were <2-37 ng/L in water and <0.5-17.5 ng/g dry weight (dw) in sediment. AHTN was <1-8 ng/L in water and <0.5-5.7 ng/g dw in sediment. Statistical relationships between SM concentrations and four environmental variables (temperature, illumination, runoff, and population density) in the Songhua River Basin were formulated. Concentration levels varied proportionately with the size of the city along the river, while the distribution patterns showed clear seasonal variations. HHCB/AHTN ratios mirrored the transfer and transmitting process of SMs. Concentrations of target compounds were correlated with each other, suggesting similar exposure sources. Environmental risk assessment of SMs presented seasonal variations and provided baseline information on SM exposure in the Songhua River Basin. PMID:25874412
Ni, Jin-Ren; Li, Xiu-Xia; Borthwick, A. G. L.
In the previous studies, a method was developed to assess soil erosion based on land use information. In this paper, we present another approach that uses environmental data to assess soil erosion. A soil erosion characteristic index EI is proposed, and its value is derived using the Analytic Hierarchy Process (AHP) technique based on standardized environmental information stored in minimum polygons that tile the erodible area under consideration. The approach is applied to a case study of the Yellow River basin, north China, where serious erosion is occurring. To represent different grades of soil erosion, the range of EI is divided into six levels according to standard grades of soil erosion intensity. The application indicates that the method deals properly with data scarcity, with the results giving a satisfactory representation of the characteristics of soil erosion in the Yellow River basin. The spatial-temporal distribution of EI in the Yellow River basin is predicted, and the results interpreted to give the long-term trend and state of soil depletion. Comparisons are given between EI and surveyed soil erosion zoning maps for the Yellow River basin at the end of the 1980s and 1990s. The output reliability and the approach applicability in smaller spatial scales are investigated in a case study of Zhifanggou basin.
Niu, Jun; Chen, Ji; Sun, Liqun
The knowledge of drought evolution characteristics may aid the decision making process in mitigating drought impacts. This study uses a macro-scale hydrological model, Variable Infiltration Capacity (VIC) model, to simulate terrestrial hydrological processes over the Xijiang (West River) basin in South China. Three drought indices, namely standardized precipitation index (SPI), standardized runoff index (SRI), and soil moisture anomaly index (SMAI), are employed to examine the spatio-temporal and evolution features of drought events. SPI, SRI and SMAI represent meteorological drought, hydrological drought and agricultural drought, respectively. The results reveal that the drought severity depicted by SPI and SRI is similar with increasing timescales; SRI is close to that of SPI in the wet season for the Liu River basin as the high-frequency precipitation is conserved more by runoff; the time lags appear between SPI and SRI due to the delay response of runoff to precipitation variability for the You River basin. The case study in 2010 spring drought further shows that the spatio-temporal evolutions are modulated by the basin-scale topography. There is more consistency between meteorological and hydrological droughts for the fan-like basin with a converged river network. For the west area of the Xijiang basin with the high elevation, the hydrological drought severity is less than meteorological drought during the developing stage. The recovery of hydrological and agricultural droughts is slower than that of meteorological drought for basins with a longer mainstream.
Han, Dongmei; Liang, Xing; Jin, Menggui; Currell, Matthew J.; Han, Ying; Song, Xianfang
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater δ2H and δ18O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water-rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. 87Sr/86Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water-rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems.
Niu, Yong; Niu, Yuan; Pang, Yong; Yu, Hui
Lake Taihu, the third-largest freshwater body in China, has many functions, including drinking water supply, flood control, cultivation, navigation, and tourism. In this study, sediment samples were collected at 31 sites from 11 inflow rivers in 2012, to investigate the distribution and concentration of heavy metals copper (Cu), zinc (Zn), lead (Pb), nickel (Ni), and chromium (Cr), and to assess their potential ecological risk. The highest mean concentration was found for Zn, followed by Cu, Cr, Pb, and Ni. Generally, heavy metal pollution was more serious in Wu Jingang River and Caoqiao River, probably because they receive large amounts of wastewater from various local industrial enterprises. The potential ecological risk values of the heavy metals were larger than 120 in more than 25.8% of the sediment samples, indicating a very high risk. The largest ecological risk was due to copper. Furthermore, the results of a principal component analysis and subsequent analysis of variance showed that heavy metal concentrations in the sediment of inflow rivers were higher than those of the lake, which created a large hazard for the aquatic ecosystems of Lake Taihu. PMID:26370278
Han, Dongmei; Liang, Xing; Jin, Menggui; Currell, Matthew J; Han, Ying; Song, Xianfang
Based on analysis of groundwater hydrochemical and isotopic indicators, this article aims to identify the groundwater flow systems in the Yangwu River alluvial fan, in the Xinzhou Basin, China. Groundwater delta(2)H and delta(18)O values indicate that the origin of groundwater is mainly from precipitation, with local evaporative influence. d-excess values lower than 10% in most groundwaters suggest a cold climate during recharge in the area. Major ion chemistry, including rCa/rMg and rNa/rCl ratios, show that groundwater salinization is probably dominated by water-rock interaction (e.g., silicate mineral weathering, dissolution of calcite and dolomite and cation exchange) in the Yangwu River alluvial fan, and locally by intensive evapotranspiration in the Hutuo River valley. Cl and Sr concentrations follow an increasing trend in shallow groundwater affected by evaporation, and a decreasing trend in deep groundwater. (87)Sr/(86)Sr ratios reflect the variety of lithologies encountered during throughflow. The groundwater flow systems (GFS) of the Yangwu River alluvial fan include local and intermediate flow systems. Hydrogeochemical modeling results, simulated using PHREEQC, reveal water-rock interaction processes along different flow paths. This modeling method is more effective for characterizing flow paths in the intermediate system than in the local system. Artificial exploitation on groundwater in the alluvial fan enhances mixing between different groundwater flow systems. PMID:19548025
Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Sun, Peng; Chen, Xiaohong; Kong, Dongdong
The flood magnitude, frequency and timing were analyzed using daily flow data for a period of 1950-2007 from 8 stations in the Tarim River basin, a typical arid inland river basin in China. The causes for flood occurrences were investigated using daily meteorological data. Results indicated that precipitation and temperature were increasing persistently since the 1980s and significant increases in precipitation and temperature were observed after the 1990s. As a result, floods amplified at annual and seasonal time scales in most tributary basins after the 1980s. The floods in the basin are mainly attributed to rainstorms and melting of glaciers and snowpack, and rainstorm-induced floods and temperature-induced floods were dominant in the basin. Extreme floods, such as the three largest recorded floods and floods with return periods > 10 years occurred mainly after the 1990s, with significant increase in flood-induced crop and livestock losses. It was found that heavy floods in many tributary basins often occurred about the same time. The Tarim River basin is a typical arid inland river basin in a high altitude zone and amplifying floods in recent decades, particularly after 1990s, is arousing considerable concern for mitigation of flood hazards. Results of this study shed light on hydrological response of arid regions to warming climate at higher latitudes in the northern hemisphere.
Song, Chunlin; Wang, Genxu; Sun, Xiangyang; Chang, Ruiying; Mao, Tianxu
Under the context of dramatic human disturbances on river system, the processes that control the transport of water, sediment, and carbon from river basins to coastal seas are not completely understood. Here we performed a quantitative synthesis for 121 sites across China to find control factors of annual river exports (Rc: runoff coefficient; TSSC: total suspended sediment concentration; TSSL: total suspended sediment loads; TOCL: total organic carbon loads) at different spatial scales. The results indicated that human activities such as dam construction and vegetation restoration might have a greater influence than climate on the transport of river sediment and carbon, although climate was a major driver of Rc. Multiple spatial scale analyses indicated that Rc increased from the small to medium scale by 20% and then decreased at the sizable scale by 20%. TSSC decreased from the small to sizeable scale but increase from the sizeable to large scales; however, TSSL significantly decreased from small (768 g·m‑2·a‑1) to medium spatial scale basins (258 g·m‑2·a‑1), and TOCL decreased from the medium to large scale. Our results will improve the understanding of water, sediment and carbon transport processes and contribute better water and land resources management strategies from different spatial scales.
Song, Chunlin; Wang, Genxu; Sun, Xiangyang; Chang, Ruiying; Mao, Tianxu
Under the context of dramatic human disturbances on river system, the processes that control the transport of water, sediment, and carbon from river basins to coastal seas are not completely understood. Here we performed a quantitative synthesis for 121 sites across China to find control factors of annual river exports (Rc: runoff coefficient; TSSC: total suspended sediment concentration; TSSL: total suspended sediment loads; TOCL: total organic carbon loads) at different spatial scales. The results indicated that human activities such as dam construction and vegetation restoration might have a greater influence than climate on the transport of river sediment and carbon, although climate was a major driver of Rc. Multiple spatial scale analyses indicated that Rc increased from the small to medium scale by 20% and then decreased at the sizable scale by 20%. TSSC decreased from the small to sizeable scale but increase from the sizeable to large scales; however, TSSL significantly decreased from small (768 g·m(-2)·a(-1)) to medium spatial scale basins (258 g·m(-2)·a(-1)), and TOCL decreased from the medium to large scale. Our results will improve the understanding of water, sediment and carbon transport processes and contribute better water and land resources management strategies from different spatial scales. PMID:27166177
Song, Chunlin; Wang, Genxu; Sun, Xiangyang; Chang, Ruiying; Mao, Tianxu
Under the context of dramatic human disturbances on river system, the processes that control the transport of water, sediment, and carbon from river basins to coastal seas are not completely understood. Here we performed a quantitative synthesis for 121 sites across China to find control factors of annual river exports (Rc: runoff coefficient; TSSC: total suspended sediment concentration; TSSL: total suspended sediment loads; TOCL: total organic carbon loads) at different spatial scales. The results indicated that human activities such as dam construction and vegetation restoration might have a greater influence than climate on the transport of river sediment and carbon, although climate was a major driver of Rc. Multiple spatial scale analyses indicated that Rc increased from the small to medium scale by 20% and then decreased at the sizable scale by 20%. TSSC decreased from the small to sizeable scale but increase from the sizeable to large scales; however, TSSL significantly decreased from small (768 g·m−2·a−1) to medium spatial scale basins (258 g·m−2·a−1), and TOCL decreased from the medium to large scale. Our results will improve the understanding of water, sediment and carbon transport processes and contribute better water and land resources management strategies from different spatial scales. PMID:27166177
Yang, Qiaofeng; Xu, Suning; Wang, Ruijiu; Li, Wenpeng; Wang, Zhiyi; Mei, Junjun; Ding, Zhilei; Yang, Peijie; Yu, Liangju; Lv, Tieying; Bai, Gang; Kang, Wei
In the study of seawater intrusion, seawater is usually taken as an end-member that mixes with other source(s). However, compared to standard seawater, the coastal seawater particularly that near the estuary, can be strongly influenced by the rivers into the sea and by coastal human activities. Their composition can be thus continuously changed and redistributed with space and time. Therefore, before investigating seawater intrusion in a certain area, it is essentially important to determine the features of the estuarine seawater (e.g. the mixture percentage between standard seawater and river water). In this study, we aimed to gain a clear situation of the seawater intrusion in Laizhou Bay, Southern Bohai, China. The issue aforementioned was investigated by comparing the stable isotopic and hydrochemical composition of the marine and river water collected in this area. Samples investigated include 5 surface water samples collected at the downstream of the Bailanghe and 7 seawater samples near the estuary of Laizhou Bay. Inert tracers (δD, δ18O, Cl, Br) and reaction tracers (Na, Mg, SO4, HCO3, Ca, NO3) are particularly analyzed. The major results are as follows: 1) All the river water samples fall below the Global Meteoric Water Line in the δD - δ18O diagram, reflecting evaporation of the upstream reservoir water. The seawater samples fall on the mixing line of standard seawater and the river water in the stable isotopic diagram. 2) The Cl-δ18O diagram indicates widespread dissolution of evaporate into the river, while high concentration of Ca and HCO3‑, as well as the SO42‑ - Cl relation of the river water samples reflect the dissolution of CO2 , carbonate and sulfate in the atmosphere and on the ground. 3) The Br/Cl ratios of seawater samples are closed to the marine ratios. This together with the plots of major ions vs. Cl suggest that the seawater samples are originated from the mixture of standard seawater and river water. Therefore, when referring to
Water scarcity and population increase have been a major limiting factor in oasis development along the Tarim River in Xinjiang, Northwest China which has very continental and dry climate, and all the agriculture and livelihoods depend on glacier melt water from Tarim River. Due to vast land reclamation along the Tarim River to grow cotton, native plant species are facing a severe competition for water, which is essential for their survival. Decreasing river runoff and inefficient water use practices by agriculture and industry has exacerbated already serious situation even worse. In addition, a large influx of migrant famers from Eastern China is being settled in this region to cultivate new agricultural lands that consumed even more water. Under those conditions, the natural riparian vegetation and the irrigation agriculture, especially along the lower reaches, suffers water shortage leading the degradation and economic losses, respectively. Along with the enlargement of irrigation area and periods of water shortage, soil salinization has become a major concern for farmers in the area. Alternative cash crops are much needed to reduce water use, so both native vegetation and human demand for water would be fulfilled. We hypothesized Apocynum Pictum, perennial herb species with multiple uses as potential substitute. Multidisciplinary approach is being used in this study to investigate three related issues to offer a basis for Apocynum's role in sustainable agriculture, such as Biomass production of Apocynum; Water budget of Apocynum; and Economic utilization of Apocynum. A.Pictum is perennial plant distributed in Central Asia and China, which its roots are perennial, while the stems die every year. Thus, A.pictum grow under the arid climate of Central Asia and provide utilization options without irrigation. We initially estimate water requirement for this plant is much less than cotton. In order to validate our hypothesis, we have measured water consumption of the
Kissel, C.; Liu, Z.; Wandres, C.
In order to use the magnetic properties of marine sediments as a tracer for past changes in the precipitation rate on land and in oceanic water masses transport and exchanges in the South China Sea, we identify and characterize the different sources of the detrital fraction among which the magnetic particles. This work is presently conducted in the framework of the Franco-Chinese LIA-MONOCL Thanks to the Westpac project, we had access to sediments collected in the deltas of the main rivers feeding the South China Sea from about 25°N to the equator. This is represented on the Asian continent by the Pearl river, the Red River, the Mekong river, by Malaysia, Sumatra and Borneo regions with minor rivers but also contributing to the South China Sea, and finally by Luzon and Taiwan. The geological formations contributing to the river sediment discharges are different from one catchment basin to another as well as the present climatic conditions. The magnetic analyses consist in the analysis of low-field magnetic susceptibility, ARM acquisition and decay, IRM acquisition and decay, back-field acquisition, thermal demagnetization of 3-axes IRM, hysteresis parameters, and FORC diagrams. The obtained parameters all together allow us to define the nature of the magnetic grains and their grain size distribution when magnetite is dominant. Some degree of variability is observed at the river mouths, illustrating different geological sources at the local/regional scale. As an average, it appears that the Southern basin of the South China Sea is surrounded by regions richer in high coercivity magnetic minerals than the northern basin. This mineral is identified as hematite while magnetites (and sulfides) are more abundant in the north. These results are complementary to the clay mineral assemblages previously determined on the same samples. The first steps of a similar study conducted on marine core-tops well distributed in the South China Sea will also be illustrated.
The Tarim River is the principle water source of the Xinjiang Uyghur Autonomous Region, NW China and the country's largest endorheic river, terminating in the Taklamakan desert. The vast majority of discharge is generated in the glaciated mountain ranges to the north (Tian Shan), south (Kunlun Shan/Tibetan Plateau) and west (Pamir Mountains) of the Taklamakan desert. The main water user is the intensive irrigation agriculture for mostly cotton and fruit production in linear river oases of the middle and lower reaches as well as a population of 10 Mil. people. Over the past 40 years, an increase in river discharge was reported, assumed to be caused by enhanced glacier melt due to a warming climate. Rapid population growth and economic development have led to a significant expansion of area under irrigation, resulting in water shortages for downstream users and the floodplain vegetation. Water resource planning and management of the Tarim require integrated assessment tools to examine changes under future climate change, land use and irrigation scenarios. The development of such tools, however, is challenged by sparse climate and discharge data as well as available data on water abstractions and diversions. The semi-distributed, process-based hydrological model SWIM (Soil and Water Integrated Model) was implemented for the headwater and middle reaches that generate over 90% of discharge, including the Aksu, Hotan and Yarkant rivers. It includes the representation of snow and glacier melt as well as irrigation abstractions. Once calibrated and validated to river discharge, the model is used to analyse future climate scenarios provided by one physically-based and one statistical regional climate model (RCM). Preliminary results of the model calibration and validation indicate that SWIM is able simulate river discharge adequately, despite poor data conditions. Snow and glacier melt account for the largest share in river discharge. The modelling results will devise
Xian, Xu-Dong; Feng, Yi-Long; Willison, J H Martin; Ai, Li-Jiao; Wang, Ping; Wu, Zhi-Neng
Two examples of the creation of naturalized areas in the littoral zone of the Three Gorges Reservoir in the urban core of Chongqing City, China, are described. The areas were created for the purpose of restoring ecological functions and services. Plants were selected based on surveys of natural wetland vegetation in the region, and experiments were conducted to discover the capacity of species of interest to survive the sometimes extreme hydrological regimes at the sites. Novel methods were developed to stabilize the plants against the rigors of extreme summer floods and constant swash, notably zigzag berms of rocks wrapped in iron mesh. The areas include native reeds, grasses, shrubs, and trees. Plant communities in the areas are zoned according to flooding stress, and their structure is less stable at lower elevations that are subjected to greater stress. The tall grass Saccharum spontaneum (widespread in Southern Asia) and the tree Pterocarya stenoptera (native to Southwest China) are notable for their utility at these sites in the center of a large city. Communities of tall reeds and grasses have become so dense and stable that they now provide the ecosystem services of capturing river sediments and resisting erosion of the river banks. It is recommended that extensive greening of the riparian zones in urban areas of the Three Gorges Reservoir be conducted for the purpose of providing ecosystem services, based in part on the experiences described here. PMID:25907628
Sun, Jing; Luo, Qian; Wang, Donghong; Wang, Zijian
Pharmaceuticals in drinking water sources (DWSs) have raised significant concerns for their persistent input and potential human health risks. Currently, little is known about the occurrence of pharmaceuticals in DWSs in China. In this study, a survey for multi-class pharmaceuticals in DWSs of five major river watersheds in China was conducted from 2012 to 2013. Samples were collected from 25 sampling sites in rivers and reservoirs. 135 pharmaceuticals were analyzed using solid-phase extraction and ultra-performance liquid chromatography tandem mass spectrometry. The results showed that a total of 70 pharmaceuticals were present in the samples, and the most frequently detected ones included sulfonamides, macrolides, antiepileptic drugs, anti-inflammatory drugs, and β-blockers, etc. Amongst these, maximum concentrations of lincomycin, sulfamethoxazole, acetaminophen and paraxanthine were between 44 ng/L and 134 ng/L, and those of metoprolol, diphenhydramine, venlafaxine, nalidixic acid and androstenedione were less than 1 ng/L. Concentrations of the two that were most persistent, DEET and carbamazepine, were 0.8-10.2 ng/L and 0.01-3.5 ng/L, respectively. Higher concentrations of cotinine were observed in warm season than in cold season, while concentrations of lincomycin were the opposite. In a causality analysis, the occurrence of pharmaceuticals in DWSs depends mainly on the detection limits of the methods, their usage and the persistence in the aquatic environment. PMID:25847753
Yi, Bai-lu; Han, Ji; Zhou, Xiang; Yang, Fang; Meng, Xing; Cao, Wu-xing; Huang, Lu-xia; Xiang, Wei-ning
Yangtze River Delta region is the world's sixth and China's largest urban agglomeration. Its rapid and massive urbanization has also caused a series of ecological and environmental impacts. This paper accounted the inventory of carbon sources and sinks in Yangtze River Delta region during 1995-2010 and analyzed their spatiotemporal patterns. It was found that the carbon sinks increased by 9.43 million tons from 1995 to 2010, in which forest ecosystem net production in Zhejiang Province was the largest contributor. The "grain for green" policy implemented since 2003 in China played a significant role in increasing the forest area and the carbon sinks. The carbon sources increased by 327 million tons, and energy consumption and industrial processes based emissions accounted for 96% of total carbon sources in 2010. Due to the large share of manufacturing and heavy industries in economy and their dependence on the high carbon intensity energy, either the amount or the growth speed of carbon emissions in Jiangsu Province was the top one in the whole region. Moreover, because the growth speed of net carbon emissions that occurred upon the built-up land was much faster than the sprawl speed of urban built-up land, the net carbon emission intensity kept increasing in the whole region, in which Jiangsu Province demonstrated the fastest increase. PMID:26259436
Pe-Piper, Georgia; Piper, David J. W.; Wang, Ying; Zhang, Yongzhan; Trottier, Corwin; Ge, Chendong; Yin, Yong
The mineralogy and geochemistry of sands were investigated in the Nandu and Wanquan rivers, Hainan Island, China, to determine the history of avulsion in the lower reaches of the Nandu River. The study also provided the opportunity to assess the utility of geochemical analysis of sands as a provenance tool. Much of the heavy mineral fraction in the rivers consists of subangular Fe-Ti oxide and Fe-(hydr)oxide minerals, and less stable minerals such as amphibole, epidote, and andalusite, whereas rounded resistant ilmenite, rutile, tourmaline and zircon predominate on the deltaic coast. Mineral assemblage and chemical composition of individual samples are related to specific source areas and river tributaries. The results demonstrate northwestwards flow of the Nandu River during the mid-Holocene and earlier avulsion of the river to the northeast coast, probably during a Late Pleistocene marine highstand. Minor basement tilting, producing little relief, was sufficient to divert the lower reaches of rivers, and this effect was enhanced where basalt flows dammed former river courses. Bulk sample REE geochemistry is largely controlled by the relative abundance of monazite, allanite, titanite, zircon and epidote, derived principally from granites. Detrital geochemistry alone shows too much variability to interpret provenance. However, a smaller number of heavy mineral analyses provide an understanding of the mineralogical origins of geochemical variation, thus enabling interpretations of provenance.
Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Xiao, Mingzhong; Xu, Chong-Yu
The assumption of stationarity of annual peak flood (APF) records at 28 hydrological stations across the Pearl River basin, China, is tested. Abrupt changes in mean and variance are tested using the Pettitt technique and the Loess method. Trends of APFs are analyzed using the Mann-Kendall method and the Spearman technique. And then the stationarity of the APF series is further investigated by GAMLSS models and long-term persistence. Results indicate that: (1) abrupt changes in mean and variance have similar influences on the changing properties of APFs, such as stationarity. Abrupt changes in mean and variance are only field significant in the East River basin; (2) the change points have a considerable impact on the detection of trends, and these may be attributed to the fact that a abrupt increase or decrease in mean values will affect the trend variations. Besides, for the APF series being free of change points and trend, the GAMLSS models also corroborate stationarity of the APF series; (3) the nonstationarity in the Pearl River basin is mainly due to the existence of the change point. However, the APF series with change points in mean and/or variance are also characterized by long-term persistence, and thus it is infeasible to assert that the abrupt behaviors and/or trends of the APF series are the result of human activities or long-term persistence, especially in the East River basin. Results of this study will provide information for management of water resources and design of hydraulic facilities in the Pearl River basin in a changing environment.
Wu, Yping; Chen, Ji
Soil erosion is a major global environmental problem that has caused many issues involving land degradation, sedimentation of waterways, ecological degradation, and nonpoint source pollution. Therefore, it is significant to understand the processes of soil erosion and sediment transport along rivers, and this can help identify the erosion prone areas and find potential measures to alleviate the environmental effects. In this study, we investigated soil erosion and identified the most seriously eroded areas in the East River Basin in southern China using a physically-based model, Soil and Water Assessment Tool (SWAT). We also introduced a classical sediment transport method (Zhang) into SWAT and compared it with the built-in Bagnold method in simulating sediment transport process along the river. The derived spatial soil erosion map and land use based erosion levels can explicitly illustrate the identification and prioritization of the critical soil erosion areas in this basin. Our results also indicate that erosion is quite sensitive to soil properties and slope. Comparison of Bagnold and Zhang methods shows that the latter can give an overall better performance especially in tracking the peak and low sediment concentrations along the river. We also found that the East River is mainly characterized by sediment deposition in most of the segments and at most times of a year. Overall, the results presented in this paper can provide decision support for watershed managers about where the best management practices (conservation measures) can be implemented effectively and at low cost. The methods we used in this study can also be of interest in sediment modeling for other basins worldwide.
Wu, Yiping; Chen, Ji
Soil erosion is a major global environmental problem that has caused many issues involving land degradation, sedimentation of waterways, ecological degradation, and nonpoint source pollution. Therefore, it is significant to understand the processes of soil erosion and sediment transport along rivers, and this can help identify the erosion prone areas and find potential measures to alleviate the environmental effects. In this study, we investigated soil erosion and identified the most seriously eroded areas in the East River Basin in southern China using a physically-based model, Soil and Water Assessment Tool (SWAT). We also introduced a classical sediment transport method (Zhang) into SWAT and compared it with the built-in Bagnold method in simulating sediment transport process along the river. The derived spatial soil erosion map and land use based erosion levels can explicitly illustrate the identification and prioritization of the critical soil erosion areas in this basin. Our results also indicate that erosion is quite sensitive to soil properties and slope. Comparison of Bagnold and Zhang methods shows that the latter can give an overall better performance especially in tracking the peak and low sediment concentrations along the river. We also found that the East River is mainly characterized by sediment deposition in most of the segments and at most times of a year. Overall, the results presented in this paper can provide decision support for watershed managers about where the best management practices (conservation measures) can be implemented effectively and at low cost. The methods we used in this study can also be of interest in sediment modeling for other basins worldwide. PMID:23137981
Pan, Baotian; Pang, Hongli; Gao, Hongshan; Garzanti, Eduardo; Zou, Yu; Liu, Xiaopeng; Li, Fuqiang; Jia, Yunxia
In its upper-middle reaches the Yellow River has high sand contents after traversing through large areas of desert and the China Loess Plateau. Understanding riverbed sediment composition in the channel is critical for the interpretation of the potential provenance, aeolian sand transport and the linkage between the Loess Plateau and the Yellow River. To address these issues, we collected 52 samples from the modern riverbed, proximal deserts, and major tributaries and used analyses of grain size, grain morphology, and heavy-mineral compositions, to establish the spatial distribution and characteristics of source regions and riverbed sediments. The heavy-mineral assemblages demonstrate significant variations for the different sections of the Yellow River. The riverbed samples from the upper reach are dominated by opaque minerals (limonite and magnetite), amphibole and epidote, with minor zircon, tourmaline and rutile. Riverbed sediments from the middle reach are garnet-rich, reflecting the widespread distribution of Mesozoic sandstones. This variability closely reflects the source regions. Our data show that seasonal tributaries (the "Ten Great Gullies") carrying detritus from the Ordos Plateau may account for the localized high garnet concentrations in the Inner Mongolia section of the upper reach. Scanning electron microscope (SEM) imaging of quartz grains show that the river sediments are characterized by composite microtextures acquired in both fluvial and eolian environments of the Hedong, Ulan Buh and Kubuq Deserts. The mineralogical composition in the upper reach (Lanzhou-Yinchuan) is similar to that of sediments in the Loess Plateau and Northeast Tibet Plateau (Western Lanzhou). However, the composition differs markedly from that in the Inner Mongolia section of the upper and middle reaches. This variation indicates that in the upper reach the Northeast Tibet Plateau contributes significant volumes of sediment to the Yellow River and Loess Plateau, but
Su, Shiliang; Li, Dan; Zhang, Qi; Xiao, Rui; Huang, Fang; Wu, Jiaping
The increasingly serious river water pollution in developing countries poses great threat to environmental health and human welfare. The assignment of river function to specific uses, known as zoning, is a useful tool to reveal variations of water environmental adaptability to human impact. Therefore, characterizing the temporal trend and identifying responsible pollution sources in different functional zones could greatly improve our knowledge about human impacts on the river water environment. The aim of this study is to obtain a deeper understanding of temporal trends and sources of water pollution in different functional zones with a case study of the Qiantang River, China. Measurement data were obtained and pretreated for 13 variables from 41 monitoring sites in four categories of functional zones during the period 1996-2004. An exploratory approach, which combines smoothing and non-parametric statistical tests, was applied to characterize trends of four significant parameters (permanganate index, ammonia nitrogen, total cadmium and fluoride) accounting for differences among different functional zones identified by discriminant analysis. Aided by GIS, yearly pollution index (PI) for each monitoring site was further mapped to compare the within-group variations in temporal dynamics for different functional zones. Rotated principal component analysis and receptor model (absolute principle component score-multiple linear regression, APCS-MLR) revealed that potential pollution sources and their corresponding contributions varied among the four functional zones. Variations of APCS values for each site of one functional zone as well as their annual average values highlighted the uncertainties associated with cross space-time effects in source apportionment. All these results reinforce the notion that the concept of zoning should be taken seriously in water pollution control. Being applicable to other rivers, the framework of management-oriented source apportionment
Zheng, C.; Cheng, G.; Xiao, H.; Ma, R.
The northwest of China is characterized by an arid climate and fragile ecosystems. With irrigated agriculture, the region is a prolific producer of cotton, wheat, and maize with some of the highest output per acre in the country. The region is also rich in ore deposits, with the reserves of numerous minerals ranked at or near the top in the country. However, the sustainability of irrigated agriculture and economic development in the region is threaten by severe eco-environmental problems resulting from both global changes and human activities, such as desertification, salinization, groundwater depletion, and dust storms. All these problems are a direct consequence of water scarcity. As global warming accelerates and rapid economic growth continues, the water shortage crisis is expected to worsen. To improve the bleak outlook for the health of ecosystem and environment in northwest China, the Chinese government has invested heavily in ecosystem restoration and watershed management in recent years. However, the effectiveness of such measures and actions depends on scientific understanding of the complex interplays among ecological, hydrological and socioeconomic factors. This presentation is intended to provide an overview of a major new research initiative supported by the National Natural Science Foundation of China to study the integration of ecological principles, hydrological processes and socioeconomic considerations toward more sustainable exploitation of surface water and groundwater resources in the Hei River Basin in northwest China. The Hei River Basin is an inland watershed located at the center of the arid region in East Asia, stretching from Qilianshan Mountains in the south to the desert in the north bordering China’s Inner Mongolia Autonomous Region and Mongolia. The total area of Hei River Basin is approximately 130,000 km2. The research initiative builds on existing research infrastructure and ecohydrological data and seeks to reveal complex
Wang, Fushun; Wang, Baoli; Liu, Cong-Qiang; Wang, Yuchun; Guan, Jin; Liu, Xiaolong; Yu, Yuanxiu
Recently, controversies about whether hydropower is still a clean energy have been arisen up with the studies about high CO 2 emission flux from hydroelectric reservoirs in boreal and tropical regions. In this study, four subtropical reservoirs and their related reaches, draining on karstic area in southwest of China, were investigated to understand their CO 2 emission, with monthly sampling strategy from July 2007 to June 2008. pCO 2 values in the surface water of these reservoirs ranged from 38 to 3300 μ atm, indicating that reservoir surface could be not only source but also sink to atmosphere CO 2 in different seasons. In Hongfeng reservoir, the flux of CO 2 from surface water varied from -9 to 70 mmol m -2 d -2 with an average of 15 mmol m -2 d -2, and in Baihua reservoir, it had a range from -8 to 77 mmol m -2 d -2 with an average of 24 mmol m -2 d -2. Hongyan reservoir had similar average flux of CO 2 to Baihua reservoir. Xiuwen had the highest average flux of CO 2 with a value of 47 mmol m -2 d -2 among the studied reservoirs. Downstream the dams discharged by hydropower generation from these reservoirs generally had quite high flux of CO 2, with an average of 489 ± 297 mmol m -2 d -2, which is close to those from tropical rivers. This means that water releasing from these reservoirs would be an important way for CO 2 emission into atmosphere. The results showed that dam construction has significant impacts on the river water chemistry, with abrupt changes in pCO 2, DO, T, pH and SIc in surface water and their outlets. In addition, with the development of thermal gradient in warm seasons, water chemistry along the water column of reservoirs also showed seasonal variations, except in Xiuwen reservoir which only has daily storage capacity.
Fu, C.; Jiang, Z.
The Gan River is the largest river in Jiangxi Province, which is located in the southeast of China and is the second branch of the Yangtze River. The Gan River flows through Jiangxi Province from the South to the North and plays an important role in the economic development for 14 counties or cities with a population of 22 million. Currently, there are 5 drinking water sources, such as the capital city, Nanchang, with a daily capacity of 0.72 million cubic meters. With the rapid economic development and increasing population in the Gan River basin, water pollution has become more serious. The water quality of the river has serious pollution on both side reaches and slight pollution on the middle reach. In the upstream, the main pollution problems come from the industrial wastewater and soil erosion, with industrial and sewage wastewater affecitng the downstream region. Based on the Provincial Environmental Quality Report of 2005, of 39 monitoring sections, the ones which reach a favorable rating of a National Standard are 71.8 per cent. The water quality in the upstream region had a good situation with 80 percent of locations meeting standards, but the water quality downstream of the capital city deteriorates and only 45.4 percent of this region can meet the standard. Standards are frequently exceeded for BOD5, TP, TN, fecal coliform, and petrolueum oil in the downstream portion. The industrial wastewater drained into the river was 139 million tons in 2005, of which Nanchang city is the largest contributor with 214 million tons of wastewater composed of 75 million tons of industrial wastewater and 139 million tons of domestic sewage. The largest COD contributor was from Ganzhou in the upstream of the river with a total of 83,800 tons in 2005. Currently, there are only two wastewater treatment facilities with daily treatment capacity of 402,000 tons along the river, which are located in the capital city. Some parameters in the treated water stil exceed the drainage
Gu, Jiawei; Chen, Jing; Sun, Qianli; Wang, Zhanghua; Wei, Zixin; Chen, Zhongyuan
This study investigates sediment source to sink relating the connection of the Yangtze River to the sea. A sediment borehole (PD) on the river coast, penetrating thick Quaternary sediments and thin sediments of late Pliocene age down to the bedrock, recorded a change in sediment provenance through time. Geochemical elements and magneto-stratigraphy help identify five zones. Zone I (the late Pliocene-the Early Pleistocene), characterized by Pb, Th, U, Ba, La, Ce, Nd, Hf, Y, Zr, Nb and Mn, indicates a local sediment provenance. This means that the study area was a localized sub-basin. Zone II (the Early Pleistocene-the mid-stage of the Early Pleistocene), with remarkable high Fe, K, As and Rb implies a new sediment provenance joining the sub-basin from the middle Yangtze reach after the opening of the Zhenjiang Gorge. Zone III (the mid-stage of Early Pleistocene-the Middle Pleistocene), featured by Ti, V, Cr, Sr, Sc, Cu, Co, Ni, Mg, Ca, Na and P suggests a further extension of sediment provenance to the upper Yangtze basin, where a large block of the E'mei basalt and carbonate occurs. This suggests that the Three Gorges valley linking the upper and middle Yangtze reaches had developed by that time. Zones IV and V (the Middle Pleistocene-the Holocene) have shown their geochemical similarity to Zone III. Discrimination ratio f(Cr, Th), f(La) and f(K, La), a new approach developed for tracing sediment provenance, confirms a basin-wide sediment source through Zones III-V. These together witness a progressive extension of the sediment provenance towards the upper Yangtze basin, corresponding to the long-term tilting effect of the Cenozoic Topographic Reversal of the eastern China continent. The timing of the Yangtze River running through into the East China Sea appears at ca. 1.0-1.2 Ma (bottom of Zone III).
Li, Baofu; Chen, Yaning; Xiong, Heigang
Much attention has recently been focused on the effects that precipitation and potential evapotranspiration (PET) have had on runoff change; however, the influence of temperature on runoff needs to be further studied. We attempted to employ the improved elasticity method to evaluate the effects of climate factors (CF, especially temperature) on runoff change for Aksu River in the arid region of northwest China. Data from Aksu River in the arid region of northwest China were analyzed to investigate changes in annual runoff and CF during the period of 1960-2010. The key findings of this study indicated that the annual runoff had a significant ( P < 0.01) increasing trend with a rate of 3.78 × 108 m3/decade, and the temperature and precipitation also exhibited significant rising trends, at a rate of 0.28 °C/decade ( P < 0.01) and 15.11 mm/decade ( P < 0.05), respectively, while PET showed a decreasing trend (22.66 mm/decade, P < 0.01). Step change point in runoff occurred in the year 1993. Thus, we employed the mean runoff and climate factors during the period 1960-1993 as the benchmark value to measure the change. In 1994-2010, mean runoff increased by 22 %. Results also revealed that temperature rising was the most important factor that increased runoff with contribution of 45 %, while precipitation and PET were responsible for 22 and 27 % of the runoff change, respectively, indicating that the runoff of increasing percentage only accounted for 6 % owing to human activities and other factors, and showed that climate variability was the main reason for the runoff change in Aksu River.
Qin, Chun-Yan; Zhou, Jin; Cao, Yong; Zhang, Yong; Hughes, Robert M; Wang, Bei-Xin
Aquatic organisms' tolerance to water pollution is widely used to monitor and assess freshwater ecosystem health. Tolerance values (TVs) estimated based on statistical analyses of species-environment relationships are more objective than those assigned by expert opinion. Region-specific TVs are the basis for developing accurate bioassessment metrics particularly in developing countries, where both aquatic biota and their responses to human disturbances have been poorly documented. We used principal component analysis to derive a synthetic gradient for four stressor variables (total nitrogen, total phosphorus, dissolved oxygen, and % silt) based on 286 sampling sites in the Taihu Lake and Qiantang River basins (Yangtze River Delta), China. We used the scores of taxa on the first principal component (PC1), which explained 49.8% of the variance, to estimate the tolerance values (TV(r)) of 163 macroinvertebrates taxa that were collected from at least 20 sites, 81 of which were not included in the Hilsenhoff TV lists (TV(h)) of 1987. All estimates were scaled into the range of 1-10 as in TV(h). Of all the taxa with different TVs, 46.3% of TV(r) were lower and 52.4% were higher than TV(h). TV(r) were significantly (p < 0.01, Fig. 2), but weakly (r(2) = 0.34), correlated with TVh. Seven biotic metrics based on TVr were more strongly correlated with the main stressors and were more effective at discriminating references sites from impacted sites than those based on TV(h). Our results highlight the importance of developing region-specific TVs for macroinvertebrate-based bioassessment and to facilitate assessment of streams in China, particularly in the Yangtze River Delta. PMID:24865385
Zeng, Yong; Cai, Yanpeng; Jia, Peng; Mao, Jiansu
Flooding is the most frequent disaster in China. It affects people's lives and properties, causing considerable economic loss. Flood forecast and operation of reservoirs are important in flood emergency management. Although great progress has been achieved in flood forecast and reservoir operation through using computer, network technology, and geographic information system technology in China, the prediction accuracy of models are not satisfactory due to the unavailability of real-time monitoring data. Also, real-time flood control scenario analysis is not effective in many regions and can seldom provide online decision support function. In this research, a decision support system for real-time flood forecasting in Yujiang River Basin, South China (DSS-YRB) is introduced in this paper. This system is based on hydrological and hydraulic mathematical models. The conceptual framework and detailed components of the proposed DSS-YRB is illustrated, which employs real-time rainfall data conversion, model-driven hydrologic forecasting, model calibration, data assimilation methods, and reservoir operational scenario analysis. Multi-tiered architecture offers great flexibility, portability, reusability, and reliability. The applied case study results show the development and application of a decision support system for real-time flood forecasting and operation is beneficial for flood control.
Yang, Xuefu; Duan, Jinming; Wang, Lei; Li, Wei; Guan, Jianling; Beecham, Simon; Mulcahy, Dennis
From data collected monthly at 26 monitoring cross sections in the Wei River in the Shaanxi Region of China during the period 2008-2012, the temporal pollution characteristics of heavy metals (Hg, Cd, Cr(VI), Pb, and As) were analyzed based on a heavy metal pollution index (HPI). The monthly HPI values of the five heavy metals in the river fluctuated greatly in 2008 and then declined gradually with time. This general trend of reduction in HPI appears not to have a seasonal variation and most likely resulted from the continued improvement in heavy metal pollution control strategies implemented by local environmental agencies combined with a significant improvement in wastewater treatment capacities. Among the five heavy metals, Cd and Pb were below 0.1 and 3 μg L(-1), respectively, at all the sampling points in the studied areas in the year 2012. The detection rates of As, Hg, and Cr(VI) were in the order of Hg > Cr(VI) > As. Hg, Cr(VI), and As exceeded, in a month of the dry season in 2012, the standard limits for category III surface waters according to the China Environment Quality Standards for Surface Water (CEQSSW). Based on the assessment using the HPI method, the pollution status of these heavy metals in water of the Wei River in the Shaanxi Region was generally at an acceptable level, but exhibited distinctive characteristics between the main stream river and tributaries. Most of the tributaries were more seriously polluted than the main river. A health risk assessment was conducted based on the Human Health Risk Assessment (HHRA) method recommended by the United States Environmental Protection Agency (USEPA). Apart from As, the health risk for the five heavy metals in the region were at acceptable levels for drinking water sources (hazard quotient (HQ) < 1, carcinogenic risk (CR) ranged from 10(-4)-10(-6)) according to the Risk Assessment Guidance for Superfund (RAGS), USEPA. Arsenic was identified as the most important pollutant of concern
Wu, Weili; Wang, Jinglin; Liu, Licheng; Jiang, Jun; Chen, Yan; Hu, Tao; Chen, Weijun
In February 2006, a large amount of unknown floating microorganisms appeared in the Hailang River (HR) in the City of Hailin, Heilongjiang Province, China. The microorganisms caused the river water fouling and threatened the clean water supply of the city. To identify the unknown floating organisms, morphological and histological inspection, PCR, cloning and sequence analysis were conducted. The results revealed that the unknown floating organisms in the river were a novel species that likely belonged to oomycetes in Saprolegniales. The organisms were named Saprolegnia sp. HL0602.
Yang, Yang; Zhou, Zhengchao; Bai, Yanying; Jiao, Wentao; Chen, Weiping
The distribution of trace elements (TEs) in water, sediment, riparian soil and dominant plants was investigated in the Fenghe River, Northwestern China. The Fenghe River ecosystem was polluted with Cd, Cr, Hg and Pb. There was a high pollution risk in the midstream and downstream regions and the risk level for Cd was much higher than that of the other elements. The average values of bioconcentration coefficient for Cd and Zn were 2.21 and 1.75, respectively, indicating a large accumulation of Cd and Zn in the studied species. With broad ecological amplitudes, L. Levl. et Vant. Trin., and L. had the greatest TE concentrations in aboveground and belowground biomass of the studied species and were potential biomonitors or phytoremediators for the study area. Multivariate techniques including cluster analysis, correlation analysis, principal component analysis, and canonical correspondence analysis were used to analyze the relations between TE concentrations in plants and various environmental factors. The soil element concentration is the main factor determining the accumulation of TEs in plants. The co-release behavior of common pollutants and TEs drove the accumulation of Hg, Cd, and As in the studied plants. Significant enrichment of some elements in the Fenghe River has led to a decline in the biodiversity of plants. PMID:27380073
Suping, P.; Flores, R.M.
Sedimentary facies types of the Pleistocene deposits of the Modern Pearl River Delta in Guangdong Province, China and Permian Member D deposits in Huainan coalfield in Anhui Province are exemplified by depositional facies of anastomosing fluvial systems. In both study areas, sand/sandstone and mud/mudstone-dominated facies types formed in diverging and converging, coeval fluvial channels laterally juxtaposed with floodplains containing ponds, lakes, and topogenous mires. The mires accumulated thin to thick peat/coal deposits that vary in vertical and lateral distribution between the two study areas. This difference is probably due to attendant sedimentary processes that affected the floodplain environments. The ancestral floodplains of the Modern Pearl River Delta were reworked by combined fluvial and tidal and estuarine processes. In contrast, the floodplains of the Permian Member D were mainly influenced by freshwater fluvial processes. In addition, the thick, laterally extensive coal zones of the Permian Member D may have formed in topogenous mires that developed on abandoned courses of anastomosing fluvial systems. This is typified by Seam 13-1, which is a blanket-like body that thickens to as much as 8 in but also splits into thinner beds. This seam overlies deposits of diverging and converging, coeval fluvial channels of the Sandstone D, and associated overbank-floodplain deposits. The limited areal extent of lenticular Pleistocene peat deposits of the Modern Pearl River Delta is due to their primary accumulation in topogenous mires in the central floodplains that were restricted by contemporaneous anastomosing channels.
Tian, Yongqiang; Huang, Bangqin; Yu, Chaochao; Chen, Nengwang; Hong, Huasheng
Phytoplankton blooms occurring in the Jiangdong Reservoir of Jiulong River, Fujian Province, South China, are a potential source of contamination of the drinking water of Xiamen (Amoy) City. To understand the main factors governing phytoplankton composition and succession, we sampled phytoplankton and measured environmental parameters in the reservoir, weekly or biweekly from Jan. 2010 to Feb. 2012. We identified 123 species of phytoplankton from 7 phyla and 74 genera. The major phyla were Chlorophyta, Bacillariophyta, Cryptophyta, Cyanophyta, and Dinophyta. The main trend in the succession of phytoplankton was from prevalence of Cryptophyta-Bacillariophyta communities to those of Chlorophyta-Cyanophyta. High cell concentrations of Cryptophyta, predominantly Komma caudate, Cryptomonas marssonii, and Cryptomonas erosa, were present in winter, associated with low river discharge and cold water. Bacillariophyta, primarily Cyclotella meneghiniana, Aulacoseira granulata, and Aulacoseira granulata var. angustissima, dominated in early spring, coinciding with high turbulence and low irradiance. During early summer and autumn, Chlorophyta, comprising Scenedesmus quadricauda, Dictyosphaerium ehrenbergianum, and Pandorina sp. were prevalent during conditions of warmer water temperatures and low turbulence. Cyanophyta, with dominance of Pseudanabaena mucicola, Merismopedia tenuissima and Raphidiopsis sp. increased throughout the summer, coinciding with higher water temperatures and lower nutrient concentrations. Dinophyta content was occasionally high during winter and summer. Peridiniopsis penardii (Dinophyta) bloomed during winter 2009, with a persistently high biomass recorded into early spring. Canonical correspondence analysis indicated that phytoplankton communities were influenced by river discharge, irradiance, water temperature, and nutrient concentrations.
He, Jianhua; Ma, Jinzhu; Zhao, Wei; Sun, Shuang
Groundwater recharge and evolution in the Shule River basin, Northwest China, was investigated by a combination of hydrogeochemical tracers, stable isotopes, and radiocarbon methods. Results showed the general chemistry of the groundwater is of SO4 2- type. Water-rock reactions of halite, Glauber's salt, gypsum and celestite, and reverse ionic exchange dictated the groundwater chemistry evolution, increasing concentrations of Cl-, Na+, SO4 2-, Ca2+, Mg2+ and Sr2+ in the groundwater. The δ18O and δ2H values of groundwater ranged from -10.8 to -7.7 and -74.4 to -53.1 ‰, respectively. Modern groundwater was identified in the proluvial fan and the shallow aquifer of the fine soil plain, likely as a result of direct infiltration of rivers and irrigation returns. Deep groundwater was depleted in heavy isotopes with 14C ages ranging from 3,000 to 26,000 years, suggesting palaeowater that was recharged during the late Pleistocene and middle Holocene epochs under a cold climate. These results have important implications for groundwater management in the Shule River basin, since large amounts of groundwater are effectively being mined and a water-use strategy is urgently needed.
Shao, M.; Zeng, L.; Hu, M.; Zhang, Y.
Pearl River delta, an economically developed region in Guangdong province China, has been suffering from serious ground-level ozone pollution. To understand the formation mechanisms of the photochemical smog in this area, a field measurement campaign involving 12 separate institutes, was performed from Oct. 1 to Nov. 4, 2004. Measurements of gas phase pollutants, performed by the different research groups using several different methods, were inter-compared. Ambient SO2, O3 and NO were measured by Peking University and Hong Kong Polytechnic University using the same methods: chemiluminescence for NOx, pulsed fluorescence for SO2, and UV photometric method for O3. VOC speciation was accomplished using canister sampling followed by GC-MS measurement by Peking University and on-line GC-FID technology by National Central University in Taiwan. Ambient concentrations of HONO, the photolysis of which is the most important source of OH radical in Pearl River delta, was measured by two wet chemical methods: one from Energy Research Foundation of the Netherlands and one developed in Peking University. Based on these inter-comparisons, the co-variation of O3, NO and VOCs at an urban site and one rural site in Pearl River delta and estimates of the relative contributions to OH production from photolysis of O3, HONO and HCHO will be presented.
HAN, C.; Liu, S.; Zhong, G.; Zhang, X.
Flood is one of the most common and serious natural calamities. Taihu Basin is located in delta region of the Yangtze River in East China (see Fig. 1). Because of the abundant rainfall and low-lying terrain, the area frequently suffers from flood hazard which have caused serious casualty and economic loss. In order to reduce the severe impacts of floods events, numerous polder areas and hydraulic constructions (including pumps, water gates etc.) were constructed. Flood Hazard Map is an effective non-structural flood mitigation tool measures. Numerical simulation of flood propagation is one of the key technologies of flood hazard mapping. Because of the complexity of its underlying surface characteristics, numerical simulation of flood propagation was faced with some special problems for the plain river network area in Taihu Basin. In this paper, a coupled one and two dimensional hydrodynamic model was established. Densely covered and interconnected river networks, numerous polder areas and complex scheduling hydraulic constructions were generalized in the model. The model was proved to be believable and stable. Based on the results of the simulation of flood propagation, flood hazard map was compiled.
Xia, Peng; Meng, Xianwei; Feng, Aiping; Yin, Ping; Wang, Xiangqin; Zhang, Jun
Historical records of metal inputs were studied by using a sediment core collected from a sand-rich mudflat in the Qinjiang River estuary, China. 210Pb chronology was used to reconstruct the fluxes of Hg, Cu, Pb, Zn, Cd, Cr and As to the core site during the last 86 years. Based on the constant initial concentration model, the sedimentation rates are 1.18 cm year-1 in the top 30 cm sandy layer and 0.92 cm year-1 in the muddy bottom layer. To compensate for grain-size and mineralogy effects on metal concentrations, aluminum was used as the normalizing element. The enrichment factors ( EF) indicate that the natural inputs had prevailed up to the early 1980s. After this period, the intensity of human activities has resulted in continual increasing trend of metals towards the surface. Recent sediment samples from the Qinjiang River estuary are found moderately enriched by Cd ( EF>1.5) and slightly enriched by other metals ( EF<1.5). Considering that the drainage area of the Qinjiang River is mostly agricultural land, the increased Cd may be due to the usage of fertilizers and pesticides in agricultural activities and the combustion of fossil fuels.
Wei, S; Lau, R K F; Fung, C N; Zheng, G J; Lam, J C W; Connell, D W; Fang, Z; Richardson, B J; Lam, P K S
The marine ecosystem of the Pearl River Delta, located on the southern coast of China, has been heavily exploited following the rapid economic growth that has occurred since the 1980s. This investigation aimed to elucidate trace organic contamination in marine biota inhabiting the Pearl River Delta area. Biota samples, including green-lipped mussels (Perna viridis), oysters (Crassostrea rivularis) and shrimp (Penaeus orientalis) were sampled from 16 stations fringing the Estuary. Elevated concentrations (on a dry weight basis) of polycyclic aromatic hydrocarbons (27.8-1041.0 ng/g), petroleum hydrocarbons (1.7-2345.4 microg/g), polychlorinated biphenyls (2.1-108.8 ng/g), DDTs (1.9-79.0 ng/g), and hexachlorocyclohexanes (n.d.-38.4 ng/g) were recorded. A human health risk assessment was conducted to estimate the risk to local residents associated with the consumption of biota collected from the Pearl River Estuary. The results indicated that PCBs were at levels that may cause deleterious health effects in populations that consume large amounts of seafood. However, it would be instructive to establish health criteria for trace organic contaminants that are specific to the local populations, in order to derive a more accurate and relevant health risk assessment. PMID:16908034
Gong, Jian; Ran, Yong; Chen, Di-Yun; Yang, Yu
The endocrine-disrupting chemicals (EDCs) was investigated in 28 riverine sediments from the Pearl River system, China and analyzed by an ultrasonication extraction and GC-MS method. The concentrations of 4-tert-octylphenol (OP), 4-nonylphenol (NP), and bisphenol A (BPA) in the sediments were in the ranges of <2.0-210, 107-16198 and <1.7-430 ng/g dw, respectively. The steroid estrogens estrone (E1) and 17β-estradiol (E2) in the sediments ranged from <1.3 to 10.9 ng/gdw and from <0.9 to 2.6 ng/gdw, respectively. The spatial distribution of these chemicals was related to the discharge of domestic and industrial wastewater along the rivers. The positive correlation between EDCs and total organic carbon indicates that sedimentary organic carbon is an important factor in controlling the distributions of EDCs. Compared with other previous studies, the ZR and DR rivers from the PRD were heavily contaminated by APs and BPA. PMID:21353256
Xu, Yan; Guo, Changsheng; Luo, Yi; Lv, Jiapei; Zhang, Yuan; Lin, Haixia; Wang, Li; Xu, Jian
The occurrence and distribution of sulfonamide and tetracycline, corresponding bacterial resistant rate and resistance genes (ARGs) and two integrase genes were investigated in seven urban rivers in Beijing, China. The total concentration of sulfonamide and tetracycline ranged from 1.3 × 10(1)-1.5 × 10(3) ng/L and 3.9 × 10(1)-5.4 × 10(4) ng/L for water, and 1.0 × 10(0)-2.7 × 10(2) and 3.1 × 10(1)-1.6 × 10(2) ng/g for sediment, respectively. The sul resistant rate was 2-3 times higher than tet resistant rate in both surface water and sediment. The average rate of sul resistance and tet resistance were up to 81.3% and 38.6% in surface water, 89.1% and 69.4% in the sediment, respectively. The sul1, tetA and tetE genes were predominant in term of the absolute abundance. The absolute abundance of ARGs in Wenyu River and Qinghe River, which were close to the direct discharging sites, were 5-50 times higher than those in the other investigated urban rivers, suggesting that the source release played an important role in the distribution of ARGs. The sul1 and sul2 genes had positive correlation (p < 0.05) with sulfonamides, and the tet resistance genes was significantly correlated with tetracyclines (p < 0.05), indicating that some ARGs and antibiotics in the urban rivers had identical sources of pollution. Considering principal component analysis, sampling sites (QH5, QH6, B1, B2, B3 and BX2) intimated that a complex interplay of processes govern fate and transport of ARGs in the junction of rivers. These results are significant to understand the fate, and the contribution of ARGs from the source release. In view of the large-scale investigation of urban rivers system in Beijing, it reflected the bacterial resistance in sewage drainage system. Such investigation highlights the management on controlling the pollutant release which was seemed as a major driving force for the maintenance and propagation of many ARGs during the development of
Sun, Wei-sheng; Gu, Qian-hong; Dong, Jing; Cheng, Qing-qing; Li, Xue-jun; Zhang, Man
In order to demonstrate macrobenthic community structure dynamics and conduct a biological evaluation of water quality in Banqiao Reservoir, we collected seasonal samples from January to November 2014 across 15 sampling sites. A total of 17 species belonging to five families, four classes, and 3 phyla were identified, including 8 chironomidae, 4 oligochaeta and 5 mollusc. Bellamya aeruginosa, Corbicula fluminea, Branchiura sowerbyi, Pelopia sp. and Glyptotendipes sp. were the important species in Banqiao Reservoir. The total density, biomass and biodiversity of marobenthos showed significant spatial and temporal differences. ANOSIM analysis indicated that the macrobenthic community structure also differed significantly among regions and seasons, and the main contributing species were Glyptotendipes sp., Pelopia sp. and B. sowerbyi. The abundance-biomass comparison curves (ABC curves) indicated that the current macrobenthic community in Banqiao Reservoir was stable. Combined with the biodiversity index, biological pollution index (BPI) and Hilsenhoff biotic index (BI), it was suggested that Banqiao Reservoir suffered slight pollution. PMID:26785570
Yin, Jun; Yan, Denghua; Yang, Zhiyong; Yuan, Zhe; Yuan, Yong; Zhang, Cheng
Based on the national precipitation dataset (0.5∘×0.5∘) 1961-2011, published by the National Meteorological Information Center of China and the five Global Climate Models provided by ISI-MIP, annual maximum precipitation for 1 day, 3 days and 7 days could be calculated. Extreme precipitation was fitted via Generalized Extreme Value (GEV) distribution to explore the changes of extreme precipitation with the return period of 20 years and 50 years during 1961-2000 and 2001-2050. Based on this, extreme precipitation projection in Huang-Huai-Hai region was done. The results showed that the five Global Climate Models could simulate the statistical features of extreme precipitation quite well, in which IPSL-CM5A-LR has the highest precision. Simulation of IPSL-CM5A-LR indicates that precipitation with the return period of 20 years and 50 years in the middle reaches of the Yellow River, middle and lower reaches of Huaihe River and plain area of the southern Haihe River will increase considerably in the future. Extreme precipitation in some of the places will even increase by more than 30%, which means that these places will face larger flood risk and their capacity to respond to flood disasters should be improved.
Emergy and economic methods were used to evaluate and compare a traditional tropical fruit cultivation system, for bananas, and three newly introduced fruit cultivation systems, for papaya, guava and wampee, on reclaimed wetlands of the Pearl River Estuary, China. The evaluations...
Au, Alan Kai Ming; Altman, Yochanan; Roussel, Josse
Purpose: This paper aims to explore Hong Kong firms' training needs in the Pearl River Delta, a booming region in the fast growing People Republic of China economy, by resorting to a human capital approach. Also, to identify the training policies selected by those firms in order to cater for those needs. Design/methodology/approach: A survey based…
Lu, Sidan; Sun, Yujiao; Zhao, Xuan; Wang, Lei; Ding, Aizhong; Zhao, Xiaohui
The connection between microbial community structure and spatial variation and pollution in river waters has been widely investigated. However, water and sediments together have rarely been explored. In this study, Illumina high-throughput sequencing was performed to analyze microbes in 24 water and sediment samples from natural to anthropogenic sources and from headstream to downstream areas. These data were used to assess variability in microbial community structure and diversity along in the Fenghe River, China. The relationship between bacterial diversity and environmental parameters was statistically analyzed. An average of 1682 operational taxonomic units was obtained. Microbial diversity increased from the headstream to downstream and tended to be greater in sediment compared with water. The water samples near the headstream endured relatively low Shannon and Chao1 indices. These diversity indices and the number of observed species in the water and sediment samples increase downstream. The parameters also differ in the two river tributaries. Community structures shift based on the extent of nitrogen pollution variation in the sediment and water samples. The four most dominant genera in the water community were Escherichia, Acinetobacter, Comamonadaceae, and Pseudomonas. In the sediments, the most dominant genera were Stramenopiles, Flavobacterium, Pseudomonas, and Comamonadaceae. The number of ammonia-oxidizing archaea in the headstream water slightly differed from that in the sediment but varied considerably in the downstream sediments. Statistical analysis showed that community variation is correlated with changes in ammonia nitrogen, total nitrogen, and nitrate nitrogen. This study identified different microbial community structures in river water and sediments. Overall this study emphasized the need to elucidate spatial variations in bacterial diversity in water and sediments associated with physicochemical gradients and to show the effects of such
Liu, Houqi; Liu, Guijian; Wang, Jie; Yuan, Zijiao; Da, Chunnian
Bohai Sea is one of the most intensively exploited region in the world and its environment has been severely impacted by the extensive human activities. The Yellow River is the most important river which connects with the Bohai Sea. Therefore, this study focused on analyzing heavy metals (HMs) in 21 surface sediment samples collected from the Yellow River, China. Sequential extraction procedure (SEP), proposed by the Community Bureau of Reference (BCR), was applied in the present study to determine the concentration and fractionation characteristics of these HMs. The aim of this study was to investigate the spatial distribution, fractionation, risk assessment, and sources of HMs, including copper (Cu), zinc (Zn), lead (Pb), chromium (Cr), iron (Fe), manganese (Mn), and nickel (Ni). The results obtained from this research will play a significant role in understanding the migration, transformation, and accumulation of HMs for future research in study area. Results of fractionation revealed that most of the HMs in the study area mainly existed in residual fraction; however, Mn mostly existed in exchangeable fraction. A high percentage of reducible fractions was found for Cu and Pb. The mean contamination factor (Cf) values indicated that Pb was the highest. It was >1 and showed moderate contamination, followed by Cr, Cu, Mn, Ni, and Zn, had <1 and indicated low contamination. Among studied HMs Pb had higher enrichment factor (EF) as compared to others. Significant positive correlations within all studied HMs and principal component analysis (PCA) results indicated their common sources, however, Pb showed the different contamination sources. The total contents of HMs in sediment were compared with the threshold effect level (TEL) and probable effect level (PEL) sediment quality guideline (TEL/PEL-based SQGs) values for trace metals in sediment, as well as literature reported data for comparative purposes, which indicated that the selected river in present study is not
Liu, Su Mei; Qi, Xiao Hong; Li, Xiaona; Ye, Hao Ran; Wu, Ying; Ren, Jing Ling; Zhang, Jing; Xu, Wei Yi
Water and sediment samples were collected from the Changjiang (Yangtze River) estuary and the adjacent East China Sea during impoundment of the river at the Three Gorges Dam. The concentrations of dissolved inorganic and organic nutrients, and particulate inorganic phosphorus and particulate organic phosphorus in the water column (PIP and POP, respectively) and sediments (SIP and SOP, respectively) were analyzed. The nutrient dynamics in salt marshes associated with the Changjiang estuary were also considered. In addition, river water samples were collected bimonthly in the lower reaches of the Changjiang. The concentrations of dissolved inorganic nutrients, PIP and POP showed temporal and spatial variations, which decreased from the coast to offshore areas. The dissolved organic nitrogen and phosphorus (P) concentrations showed patchy distributions, but were consistent with the distribution of phytoplankton biomass. Phosphorus is the major limiting element for phytoplankton growth. Among the various P forms, particulate P represented 38-52% of total P. The PIP and POP concentrations showed clear seasonal variations corresponding to the occurrence of the levels of suspended particulate matter. The P accumulation rates showed a decreasing trend from the coast to offshore areas, and high P burial efficiencies were found; the latter were related to a low benthic PO43 - flux and high sediment accumulation rates. The potential bioavailable P was estimated to be 65-70% of total P, of which more than two-thirds was regenerated in the water column. The salt marsh in the Changjiang estuary plays an important ecological role in nutrient transport from the river to offshore areas, and increased P limitation.
Yang, Jingbiao; Wang, Yi Chen; Guo, Luo; Xue, Dayuan
Located in Qinghai Province of China, the Three Rivers Headwaters Region is the source region of the Yangtze, Yellow and Lantsang Rivers, and plays an important role in biodiversity conservation and regulating water supply. Despite many efforts on land use change in Qinghai, knowledge of the spatial variation of land use change is still lacking. This study examines the patterns of land use change across various watersheds, prefectures and the temple surroundings. Remote sensing images of 1987, 1997 and 2007 were analyzed to derive land use distributions; patterns and structures of the landscape were then quantified with landscape metrics. The results illustrated that the Yangtze River headwater region had more diverse and more evenly distributed landscape, while the Lantsang and the Yellow headwater regions showed a decline in landscape diversity. Comparison of the land use patterns of four prefectures revealed that Yushu Prefecture experienced an increase in landscape diversity from 1987 to 2007 while the land use patches in Guoluo Prefecture exhibited more aggregated patterns than other prefectures. Analysis of the spatial variations of land use change in the temple surroundings illustrated that 19.7% and 35.9% of the temples in Guoluo and Yushu Prefectures, respectively, encountered land use change for their immediate areas within 2 km. Comparison of the surroundings of temples and human settlements found that land use change was not evenly distributed, and that greater land use change had occurred for the surroundings of human settlements. Such findings provided insights into the spatial variation of land use change in the Three Rivers Headwaters Region. PMID:25816147
Zheng, C.; Cheng, G.; Fu, B.; Song, C.; Xiao, H.
This presentation provides an overview of a major new research initiative supported by the National Natural Science Foundation of China for an integrative study of ecological principles, hydrological processes and socioeconomic considerations in the Heihe River Basin (HRB) in northwest China. The HRB is an inland watershed located at the center of the arid zone in East Asia, stretching from the Qilianshan Mountains in the south to the Gobi desert in the north bordering China's Inner Mongolia Autonomous Region and Mongolia (Figure 1). The total area of the Heihe River Basin is approximately 130,000 km2, covering a wide range of climatic, geographical, ecological and hydrogeological conditions, from the high-altitude alpine ecosystem with glaciers and permafrost in the upper HRB, to the intensively irrigated agricultural ecosystem in the middle HRB, to the fragile, thinly vegetated desert ecosystem in the lower HRB. The new research initiative builds on the existing observatory infrastructure and long-term ecohydrological datasets since the 1950s. It seeks to reveal the complex interactions across multiple spatiotemporal scales between the basin hydrologic cycle and diverse ecosystem functioning in a water-limited environment with about 60 new, well-coordinated research projects supported for the next five years. These projects may be categorized into five groups: 1) Basin-wide transect sampling, airborne and remote sensing experimentation to collect vegetation, soil, DEM, ET, and other relevant data and build comprehensive databases and data services; 2) Observation, measurement and modeling of regional climate variability, precipitation and water resources distribution, ecosystem productivity, and development of framework for integrated models and decision support systems; 3) Study of the upper HRB, with emphasis on glaciers, snow, and permafrost; 4) Study of the middle HRB, with emphasis on surface-groundwater interactions and agriculture water use efficiency; and
Yan, Chang-An; Zhang, Wanchang; Zhang, Zhijie
A watershed hydrological model, hydrological simulation program-Fortran (HSPF), was applied to simulate the spatial and temporal variation of hydrological processes in the Jiaoyi watershed of Huaihe River Basin, the heaviest shortage of water resources and polluted area in China. The model was calibrated using the years 2001-2004 and validated with data from 2005 to 2006. Calibration and validation results showed that the model generally simulated mean monthly and daily runoff precisely due to the close matching hydrographs between simulated and observed runoff, as well as the excellent evaluation indicators such as Nash-Sutcliffe efficiency (NSE), coefficient of correlation (R (2)), and the relative error (RE). The similar simulation results between calibration and validation period showed that all the calibrated parameters had a certain representation in Jiaoyi watershed. Additionally, the simulation in rainy months was more accurate than the drought months. Another result in this paper was that HSPF was also capable of estimating the water balance components reasonably and realistically in space through the whole watershed. The calibrated model can be used to explore the effects of climate change scenarios and various watershed management practices on the water resources and water environment in the basin. PMID:25013863
Yan, Chang-An; Zhang, Wanchang; Zhang, Zhijie
A watershed hydrological model, hydrological simulation program-Fortran (HSPF), was applied to simulate the spatial and temporal variation of hydrological processes in the Jiaoyi watershed of Huaihe River Basin, the heaviest shortage of water resources and polluted area in China. The model was calibrated using the years 2001–2004 and validated with data from 2005 to 2006. Calibration and validation results showed that the model generally simulated mean monthly and daily runoff precisely due to the close matching hydrographs between simulated and observed runoff, as well as the excellent evaluation indicators such as Nash-Sutcliffe efficiency (NSE), coefficient of correlation (R2), and the relative error (RE). The similar simulation results between calibration and validation period showed that all the calibrated parameters had a certain representation in Jiaoyi watershed. Additionally, the simulation in rainy months was more accurate than the drought months. Another result in this paper was that HSPF was also capable of estimating the water balance components reasonably and realistically in space through the whole watershed. The calibrated model can be used to explore the effects of climate change scenarios and various watershed management practices on the water resources and water environment in the basin. PMID:25013863
Zhao, Jun; Liu, Qiuxia; Lin, Liqing; Lv, Huafang; Wang, Yao
Around 2000, China began to address the comprehensive restoration of its urban rivers and attempt to restore river ecosystem services. This paper reports an integrated contingent valuation of the ecosystem services of Zhangjiabang Creek in Shanghai, which is in the most developed region of China. A total of 1440 questionnaires were delivered, and 1153 were returned as usable in August 2008. The willingness to pay for the restoration of the urban river is 20.22 RMB (2.91 USD) per month per household under the payment card and 110.64 RMB (15.92 USD) under the dichotomous format. Several important methodological issues of the contingent valuation method (CVM) are observed, including the disparity between willingness to pay and willingness to accept, the difference between payment card and dichotomous choice question formats, and the comparison of different models in welfare estimation using dichotomous choice data. Several new findings are disclosed for these three issues of CVM. PMID:23707722
Zhang, Daolai; Liu, Jinqing; Jiang, Xuejun; Cao, Ke; Yin, Ping; Zhang, Xunhua
The distribution, sources and risk assessment of 16 polycyclic aromatic hydrocarbons (PAHs) of surface sediments in the Luan River Estuary, China, have been investigated in the research. The results indicated that the total concentrations of 16 PAHs in surface sediments of the Luan River Estuary ranged from 5.1 to 545.1 ng g(-1)dw with a mean value of 120.8 ng g(-1)dw, which is relatively low in comparison with other estuaries around the world. The PAHs in the study area were mainly originated from pyrogenic sources. Besides, PAHs may be contaminated by petrogenic PAHs as indicated by the selected ratios of PAHs, the 2-tailed Pearson correlation analysis and principal components analysis at different sites. The result of the ecological risk assessment shows little negative effect for most individual PAHs in surface sediments of the Luan River Estuary, China. PMID:26616744
Zhang, Kai; Wei, Yan-Li; Zeng, Eddy Y
Rapid economic growth in South China (including Guangdong Province, Hong Kong, and Macau), particularly within the Pearl River Delta region, has resulted in severe pollution of the natural eco-environment in the last three decades. Large amounts of monitoring data on organic pollution in the Pearl River Delta have been accumulated, which allows us to conduct a fairly comprehensive assessment of the state of the Pearl River Delta and elucidate spatial and temporal patterns of pollution on a regional scale. Of various causes for environmental deterioration, negative impact from persistent organic pollutants (POPs) is a global concern. This review examines the current levels and distribution patterns of several POPs, namely DDT (and its metabolites DDD and DDE), hexachlorocyclohexanes, and polybrominated diphenyl ethers, in various environmental compartments of South China. The general information on environmental occurrence, regional behaviors, ecological effects, and human exposure of these POPs in this region are reviewed. PMID:23245873
Dong, D.; Guo, Z.; Liu, X.; Hua, X.; Liang, D.
Polycyclic aromatic hydrocarbons (PAHs), a class of typical persistent organic pollutants, widely exist in the environment and are potentially harmful to human health. They can enter the waters through atmospheric deposition, soil leaching, shipping, sewage discharges and surface runoff. In recent years, many studies on the distributions of PAHs in major rivers, lakes and bays around the world have been carried out. In this study, 9 surface sediments (0-10cm) were sampled from the Songhua River in Jilin and Heilongjiang provinces. The contents of 16 PAHs in the US Environmental Protection Agency list of priority pollutants were determined and their spatial distributions were discussed. Sediment cores (50cm length) in three oxbow lakes in this area were also collected and cut into 2 cm thickness sub-samples. PAHs concentrations in these samples were determined and the cores were dated using a 210Pb geochronology technique. Finally, the sedimentary history of PAHs in the Songhua River since the 1920s was revealed. Results indicated that total concentration of the 16 PAHs analyzed in the surface sediments was 187-2079 ng/g (dry weight), and the mean was 1029 ng/g. Sediments collected from near urban areas (Jilin and Harbin City) contained higher PAHs content. Compared with the domestic and international rivers, the PAHs content in this river sediments is at a medium level. The PAHs profiles showed that 2-3 ring PAHs, especially naphthalene, were dominant in all of the samples. Sedimentary flux can reflect the accumulating history of pollutants better. The PAHs fluxes were low and varied little from the 1920s to 1970s, but higher PAH fluxes were found since the 1980s in each core (Fig. 1). The PAHs sedimentary flux near Harbin City (Shuangcheng) was found changed remarkably. We inferred that the PAHs might be influenced by hydrological conditions, population mobility and economic activity in this area. PAHs sedimentary record in the Songhua River revealed that the
Fan, Juntao; Semenzin, Elena; Meng, Wei; Giubilato, Elisa; Zhang, Yuan; Critto, Andrea; Zabeo, Alex; Zhou, Yun; Ding, Sen; Wan, Jun; He, Mengchang; Lin, Chunye
Integrated risk assessment approaches allow to achieve a sound evaluation of ecological status of river basins and to gain knowledge about the likely causes of impairment, useful for informing and supporting the decision-making process. In this paper, the integrated risk assessment (IRA) methodology developed in the EU MODELKEY project (and implemented in the MODELKEY Decision Support System) is applied to the Taizi River (China), in order to assess its Ecological and Chemical Status according to EU Water Framework Directive (WFD) requirements. The available dataset is derived by an extensive survey carried out in 2009 and 2010 across the Taizi River catchment, including the monitoring of physico-chemical (i.e. DO, EC, NH3-_N, chemical oxygen demand (COD), biological oxygen demand in 5 days (BOD5) and TP), chemical (i.e. polycyclic aromatic hydrocarbons (PAHs) and metals), biological (i.e. macroinvertebrates, fish, and algae), and hydromorphological parameters (i.e. water quantity, channel change and morphology diversity). The results show a negative trend in the ecological status from the highland to the lowland of the Taizi River Basin. Organic pollution from agriculture and domestic sources (i.e. COD and BOD5), unstable hydrological regime (i.e. water quantity shortage) and chemical pollutants from industry (i.e. PAHs and metals) are found to be the main stressors impacting the ecological status of the Taizi River Basin. The comparison between the results of the IRA methodology and those of a previous study (Leigh et al. 2012) indicates that the selection of indicators and integrating methodologies can have a relevant impact on the classification of the ecological status. The IRA methodology, which integrates information from five lines of evidence (i.e., biology, physico-chemistry, chemistry, ecotoxicology and hydromorphology) required by WFD, allows to better identify the biological communities that are potentially at risk and the stressors that are most
"Since the 1980s, it has been possible for the Chinese peasant household to diversify its economic base by making use of its social networks to place members in a distant community as migrant workers. Through a microstudy of 50 such migrants in Kaiping County in the Pearl River Delta region, this article illustrates the interplay between macro, meso, and micro factors in the causes and processes of circulatory mobility in post-Mao China. It is found that Hong Kong's search for cheap labor, the PRC's household registration system, and Kaiping's strong localism provide the context in which migrants and their households have to adjust. The particular behavior pattern of these migrants also bears the stamp of their rational household decision-making processes as well as their feelings of moral obligation toward their kin in their community of origin." PMID:12287570
ZHOU, Wei; LI, Min-hui; WANG, Chun-ping; QI, Mi
It is practically difficult to differentiate Placocheilus robustus and Placocheilus caudofasciatus from Red River drainage of China. Without stated reasons, P. robustus has been assumed as the synonyms of P. caudofasciatus. The present study aims to decipher the morphological differences between two species so as to provide reliable clues for their classification by multivariate morphometry. A total of 72 specimens of two species in genus Placocheilus were examined. Besides morphological character comparisons, 10 anatomic landmarks were utilized and 23 frame structures and 15 general characters measured. The scatter plot results of principal component analysis showed that all specimens were clustered together and could not be defined as two distinct species. No significant morphological differences existed in four diagnostic characters between P. robustus and P. caudofasciatus. Thus the results of the present study fail to support P. robustus as a valid and independent species. PMID:26646572
Sun, Mingyang; Huang, Linglin; Tan, Lisha; Yang, Zhe; Baig, Shams Ali; Sheng, Tiantian; Zhu, Hong; Xu, Xinhua
The water quality and cyanobacterial variation of rivers surrounding southern Taihu Lake, China were purposively monitored from 2008 to 2010. Trophic level index (TLI) was used to evaluate the trophic levels of southern Taihu Lake. Results showed a considerable decline in the monitored data compared with 2007, and the data showed downward trends year after year. The TLI decreased from 55.6 to 51.3, which implied that southern Taihu Lake was mildly eutrophic. The water quality and cyanobacterial variation indicated a positive response to the adopted control measures in the southern Taihu Lake basin, but the intra- and inter-annual variability was still quite varied. High concentrations of nitrogen and phosphorus typically lead to algae outbreaks, however, the cyanobacteria growth may result in a decline of the concentration of nitrogen and phosphorus. Temperature and other weather conditions are also important factors for algae outbreaks; the risk of blue-green algal blooms still persists. PMID:23789569
Hu, Jian; Liu, Congqiang; Zhang, Guoping; Zhang, Yanlin; Li, Siliang; Zhao, Zhiqi; Liu, Baojian; Guo, Qinjun
The Liao River drainage basin, which is one of China's seven major rivers basins, is located in northeast China. This region is characterized by important industrial bases including steel factories and oil and chemical plants, all of which have the potential to contribute pollutants to the drainage basin. In this study, 16 polycyclic aromatic hydrocarbons (PAHs) in water and suspended particulate matter (SPM) in the major rivers of the Liao River drainage basin were identified and quantified by gas chromatography mass spectrometry (GC/MS). The total PAH concentrations ranged from 0.4 to 76.5 μg/g (dry weight) in SPM and 32.6 to 108 ng/L in surface water, respectively. Low-ring PAHs (including two- and three-ring PAHs) were dominant in all PAH samples, and the level of low-ring PAHs in surface water was higher than that in SPM. The proportion of two-ring PAHs was the highest, accounting for an average of 68.2 % of the total PAHs in surface water, while the level of three-ring PAHs was the highest in SPM, with an average of 66.3 %. When compared with other river systems, the concentrations of PAHs in the Liao River drainage basin were lower. Identification of the emission sources based on diagnostic ratios suggested petroleum and fossil fuel combustion were important contribution to PAHs in the study area. PMID:26972927
Zhai, Xiaoyan; Xia, Jun; Zhang, Yongyong
Water quality deterioration is a prominent issue threatening water security throughout the world. Huai River Basin, as the sixth largest basin in China, is facing the most severe water pollution and high disturbance. Statistical detection of water quality trends and identification of human interferences are significant for sustainable water quality management. Three key water quality elements (ammonium nitrogen: NH3-N, permanganate index: CODMn and dissolved oxygen: DO) at 18 monitoring stations were selected to analyze their spatio-temporal variations in the highly disturbed Huai River Basin using seasonal Mann-Kendall test and Moran's I method. Relationship between surrounding water environment and anthropogenic activities (point source emission, land use) was investigated by regression analysis. The results indicated that water environment was significantly improved on the whole from 1994 to 2005. CODMn and NH3-N concentrations decreased at half of the stations, and DO concentration increased significantly at 39% (7/18) stations. The high pollution cluster centers for both NH3-N and CODMn were in the middle stream of Shaying River and Guo River in the 2000s. Water quality of Huai River Basin was mainly influenced by point source pollution emission, flows regulated by dams, water temperature and land use variations and so on. This study was expected to provide insights into water quality evolution and foundations for water quality management in Huai River Basin, and scientific references for the implementation of water pollution prevention in China. PMID:25108800
Hu, Y.; Lu, Y.; Zheng, C.
The Heihe River basin (HRB) is the second largest endorheic river basin of China located in arid northwestern China, characterized by runoff-generating mountainous terrains in the upstream, well developed irrigated agriculture in the middle basin, and Gobi deserts in the downstream. We sampled the Heihe river water along the middle section during base flow and high discharge (irrigation periods), as well as groundwater scattered in the middle HRB. δ13C-DIC, nitrate, and cation were measured to constrain water and carbon sources. Considering positive correlations of δ13C-DIC with Ca2+ and Mg2+ concentrations and the distribution of maize in the midstream areas, the weathering of silicates with CO2 from C4 plants was the main source of DIC in the Heihe river. During base flow and high discharge, river water δ13C-DIC had similar values (-2.26‰ for average) at the mountain exit and sharply fell to averages of -4.36‰ at the baseflow and -5.80‰ at high discharge, as the river enters the midstream plain where larger fluxes of groundwater discharging to the river water were observed. δ13C-DIC values during high discharge than during baseflow conditions can be attributed to lower inputs of groundwater and stronger soil respiration in the growing season. A negative correlation between δ13C-DIC and nitrate at high discharge indicated stronger influences of soil respiration on river water DIC through irrigation return flows. The binary mixing model using groundwater and mountain exit as end-members was used to evaluate longitudinal variation in the fraction of groundwater contributing to river water. The proportion of groundwater increased from the boundary of the diluvial fan (about 20% at high discharge and 45% at base flow) to the exit edge of the middle basin (about 45% at high discharge and 60% at base flow).
Role of river bends for the formation and evolution of channel bedforms: Combined field studies and numerical modeling from the tidally influenced zones of the Yellow River, China, and Mississippi River, USA.
Ma, H.; Nittrouer, J. A.; Moodie, A.; Calson, B.; Parker, G.
River bedforms represent the unstable interface between fluid flow and the granular channel bed, and these features play an important role for modifying flow resistance and sediment transport rates, and thus influencing river morphology. Although widely observed in natural rivers, bedforms are difficult to measure quantitatively and are rarely connected to other fluvial morphological processes. This study presents high-resolution channel bathymetric data from the tidally influenced, lowermost Yellow River, China, collected using a multibeam swath profiler. Repeat surveys were conducted over rising and flood discharge conditions, which is the first such kind of survey in Yellow River. The bathymetry data show that for all water discharges, a flat bed, devoid of a thalweg or dunes, persists within straight-reach segments near the bends of the Yellow River, despite the bed consisting of fine sand. Interestingly, in bend segments, the channel deepens, and linear dunes develop. Moreover, as the water discharge increases over time, the edge of dune field contained in the bend segments propagates into the adjacent upstream and downstream straight-reach segments. In contrasting case study, Nittrouer et al. (2008) reported persistent dune field in the straight reaches of the tidally influenced Mississippi River; however these dunes disappear in neighboring river bends. Based on the two cases of the Yellow and Mississippi Rivers, which have fundamentally different conditions of water-to-sediment discharge ratios, the threshold condition of bedform formation and stability are evaluated, and connected to local conditions of river bend morphology. This work improves the understanding of the co-evolution of bedforms and flow conditions in river bends, which are intertwined and important morphological processes that affect fluvial-deltaic sediment transport dynamics. In addition, the straight-bend structure is a basic element of river morphology, and so the results of this study
Li, Qingbo; Zhang, Haibo; Luo, Yongming; Song, Jing; Wu, Longhua; Ma, Jianmin
Organochlorine pesticides were used extensively in the Yangtze River Delta, China. However, knowledge about their residual levels and environmental fates in soils of this area is limited. This paper presents the residue isomers and spatial pattern of dichlorodiphenyltrichloroethane (DDT) in soils across 17 main cities in the Yangtze River Delta. Forty-three soil surface (0-15 cm) samples were collected during a field campaign conducted in October 2003 in the Delta. Six DDT isomers (1-[2-chlorophenyl]-1-[4-chlorophenyl]-2,2-dichloroethane [o,p'-DDD], 1-[2-chlorophenyl]-1-[4-chlorophenyl]-2,2-dichloroethylene [o,p-'DDE], 1,1,1-trichloro-2-[p-chlorophenyl]-2-[o-chlorophenyl]ethane [o,p'-DDT], p,p'-dichlorodiphenyldichloroethane [p,p'-DDD], p,p'-dichlorodiphenyldichloroethylene [p,p'-DDE], p,p'-dichlorodiphenyltrichloroethane [p,p'-DDT]) were detected using gas chromatography. The results show that p,p'-DDE was the dominant isomer in the soil samples. The levels of DDT are generally low in soils of this area and are comparable to DDT levels in other cities in China and in soils from developed countries such as the United States and Germany. The isomer ratios of o,p'-DDT to p,p'-DDT and DDT to (DDD + DDE) were employed to identify the source of DDT. The computed ratios implied that the source of DDT might be related to the application of dicofol, an acaricide manufactured from technical DDTs and mainly used on cotton fields to treat mites. PMID:18092878
Chen, She-Jun; Luo, Xiao-Jun; Lin, Zhen; Luo, Yong; Li, Ke-Chang; Peng, Xian-Zhi; Mai, Bi-Xian; Ran, Yong; Zeng, Eddy Y
The present study provides information on the time trend of PBDEs in three sediment cores from the Pearl River Estuary (PRE), South China, using 210Pb dating technique. The sigmaPBDEs (except for BDE 209) concentrations in all sediment cores increased gradually from the bottom (mid-1970s) to the middle layer (later 1980s and early 1990s) followed by different temporal trends in different locations to the surface sediments, reflecting the variations in the consumption of commercial penta-BDEs mixture in different regions of the Pearl River Delta. The BDE 209 concentrations remained constant until 1990 and thereafter increased exponentially to the present, with doubling times of 2.6 +/- 0.5-6.4 +/- 1.6 years, suggesting the increasing market demands for deca-BDE mixture after 1990 in China. The inventories of sigmaPBDEs and BDE 209 in sediments of the PRE were 56.0 and 368.2 ng cm(-2), respectively, and the total burden of PBDEs in the PRE were estimated at 8.6 metric tons. The current sigmaPBDEs and BDE 209 fluxes to the PRE were 2.1 and 29.7 ng cm(-2) yr(-1), respectively. The concurrent increase of BDE 209 fluxes and the annual gross industrial output values of electronics manufacturing revealed that the rapid growth of electronics manufacturing in this region since the early 1990s was responsible for the sharp rise of BDE 209 fluxes in the past decade. The PBDE congener compositions of the cores indicated the various input pathways for PBDEs transport to different locations of the estuary. PMID:17874760
Guo, B.; Xie, T.; Liu, G.
Biyun Guo1,21College of Marine Science and Technology, Zhejiang Ocean University, Zhoushan 316004,China; 2State Key Laboratory of Hydroscience and Engineering, Tsinghua University, Beijing 100084, China Abstract: The great Wenchuan earthquake(Ms=8.0) occurred on May 12, 2008 in the southwestern China which triggerednumerous landslides and collapses that providedflows of an abundant unconsolidated material of debris. Landslides and debris flows were very active and caused river channel change over the affected mountain area. River channel changes due to the earthquake.Many potentially dangerous debris filledgullies have yet to be identified. In this paper,we present a study in the Longxi river watershed of the upper Min River located in Dujiangyan, discussingthe unconsolidated deposits and debris flows and their relationship with the riverbed changes. The secondary geological disasters triggered by this earthquake is delineated across the Longxi Rvier basin. Based on remote sensing and image interpretation of two QuickBird panchromatic images and comparison between two DEM data of different time periods, wevalidatedthe data with field survey by a differential GPS and laser rangefinder. Several variables were systematically measured (width, slope, bed level change, sediment size) along an18.22 km stretch of the river for specific sites. We have found from the study that: (1) the significant feature of geological disaster was near the Longxi river, where it had the mostintensity; (2) the longitudinal profile of channel bed was changed; (3) channel changes were associated with the land use and cover change, especially with the forest degradation and reforest, and post-quake reconstruction;(4)the landslide and debris flows caused the morphology changes in the Longxi River watershed, leading to sharp changes of the riverbed profiles and the slope in the upper and lower reaches. Keywords: Earthquake ;landslides; debris flows; channel change; riverbed evolution
Jingqiu, Piao; Changyuan, Tang; Xianfang, Song
Phosphorus (P) forms, with respect to sediment characteristics, and an in-stream sluice were studied in the river-lake system, Huai River catchment area, China. The mean of total P in sediments in the mainstream of the Huai River was higher than that in the Hongze Lake. It was found that P fractions varied in the sediments throughout the river and lake. Detrital-P was the dominant P fraction in the mainstream and organic P and detrital-P were the dominant P fractions in the lake, which could indicate: biologically available and non-biologically available forms. Useful information for the interpretation of P fractions could also be obtained from major sediment characteristics. Whether the relations between P fractions and grain size characteristics were significant or weak, 0.125 mm was a threshold grain size for P fraction distribution in sediment. In addition, the Bengbu Sluice, one of the most important in-stream facilities in the Huai River catchment area, regulated not only the transport of P in sediments upstream and downstream of the sluice, but also the distribution of P fractions in the river-lake system. Therefore, it was confirmed that nutrient loadings could be prevented from reaching the watershed, as well as improved ecological diversity by integrating sluice operation. PMID:26287843
Zhang, Di; Tao, Yi; Liu, Xiaoning; Zhou, Kuiyu; Yuan, Zhenghao; Wu, Qianyuan; Zhang, Xihui
Urban wastewater treatment plant (WWTP) effluent as reclaimed water provides an alternative water resource for urban rivers and effluent will pose a significant influence on the water quality of rivers. The objective of this study was to investigate the spatial and temporal variations of water quality in XZ River, an artificial urban river in Shenzhen city, Guangdong Province, China, after receiving reclaimed water from WWTP effluent. The water samples were collected monthly at different sites of XZ River from April 2013 to September 2014. Multivariate statistical techniques and a box-plot were used to assess the variations of water quality and to identify the main pollution factor. The results showed the input of WWTP effluent could effectively increase dissolved oxygen, decrease turbidity, phosphorus load and organic pollution load of XZ River. However, total nitrogen and nitrate pollution loads were found to remain at higher levels after receiving reclaimed water, which might aggravate eutrophication status of XZ River. Organic pollution load exhibited the lowest value on the 750 m downstream of XZ River, while turbidity and nutrient load showed the lowest values on the 2,300 m downstream. There was a higher load of nitrogen and phosphorus pollution in the dry season and at the beginning of wet season. PMID:27003063
Strokal, Maryna; Kroeze, Carolien; Wang, Mengru; Bai, Zhaohai; Ma, Lin
Chinese agriculture has been developing fast towards industrial food production systems that discharge nutrient-rich wastewater into rivers. As a result, nutrient export by rivers has been increasing, resulting in coastal water pollution. We developed a Model to Assess River Inputs of Nutrients to seAs (MARINA) for China. The MARINA Nutrient Model quantifies river export of nutrients by source at the sub-basin scale as a function of human activities on land. MARINA is a downscaled version for China of the Global NEWS-2 (Nutrient Export from WaterSheds) model with an improved approach for nutrient losses from animal production and population. We use the model to quantify dissolved inorganic and organic nitrogen (N) and phosphorus (P) export by six large rivers draining into the Bohai Gulf (Yellow, Hai, Liao), Yellow Sea (Yangtze, Huai) and South China Sea (Pearl) in 1970, 2000 and 2050. We addressed uncertainties in the MARINA Nutrient model. Between 1970 and 2000 river export of dissolved N and P increased by a factor of 2-8 depending on sea and nutrient form. Thus, the risk for coastal eutrophication increased. Direct losses of manure to rivers contribute to 60-78% of nutrient inputs to the Bohai Gulf and 20-74% of nutrient inputs to the other seas in 2000. Sewage is an important source of dissolved inorganic P, and synthetic fertilizers of dissolved inorganic N. Over half of the nutrients exported by the Yangtze and Pearl rivers originated from human activities in downstream and middlestream sub-basins. The Yellow River exported up to 70% of dissolved inorganic N and P from downstream sub-basins and of dissolved organic N and P from middlestream sub-basins. Rivers draining into the Bohai Gulf are drier, and thus transport fewer nutrients. For the future we calculate further increases in river export of nutrients. The MARINA Nutrient model quantifies the main sources of coastal water pollution for sub-basins. This information can contribute to formulation of
Qian, Yun; Leung, Lai R.
Driven by the complex topography, inhomogeneous land surface conditions and large-scale circulation exhibiting strong variability at various time scales, the hydroclimate of China presents many unique features and poses a great challenge for climate modeling. This paper provides detailed analyses of observations and a 20-year regional climate simulation to improve our understanding of the diverse hydroclimate regimes in China. Eastern China is greatly influenced by the East Asian monsoon, leading to heavy summer rainfall that exhibits large variations at the intraseasonal and interannual time scales. The Hai River and Huaihe River basins feature the largest interannual variations in summer rainfall, with the Middle and Lower Yangtze River and Pearl River basins showing the next highest variability. In the wettest regions of the Middle and Lower Yangtze River basin and Southeast Coast, the land surface plays a comparatively passive role as evaporation is not limited by soil moisture, and boundary layer and precipitation processes are only weakly influenced by soil wetness. In contrast, northern and western China are marked by dryer and less cloudy conditions, and interannual variations in summer rainfall are typically half of that in eastern China. Precipitation is largely balanced by evapotranspiration. The land surface plays a more active role in the water cycle in these regions. This is supported by the strong correlations between soil moisture and sensible heat flux, evaporative fraction, and mixed layer depth, indicating a strong influence of soil wetness on atmospheric stability and precipitation processes. The overall spatial distribution, seasonal variations, and extreme precipitation are well simulated by the regional climate model. However, the simulation produces more rainfall associated with the lower rain rates in central and southern China. This suggests that some mechanisms responsible for heavy rainfall may not be properly simulated by the model due
Yu, Haiyan; Yu, Zhiming; Song, Xiuxian; Cao, Xihua; Yuan, Yongquan; Lu, Guangyuan
The Changjiang River estuary is the most eutrophic estuary in China. Although anthropogenic input from the Changjiang River (the third-largest river in the world) is considered the main source of nitrogen, the contributions of newly regenerated nitrogen from deep waters may be underestimated, in part due to the lack of information on the nitrogen biogeochemical processes that are occurring. The nitrogen stable isotope ratio is widely used as an indicator of the source of nitrogen and nitrogen transformation processes including assimilation, nitrification, nitrogen fixation and mineralization. To study the biogeochemical processes in the Changjiang River estuary, seasonal variations in the nitrogen stable isotope ratio of nitrate (δ15NO3), salinity, temperature, dissolved oxygen concentration, chlorophyll a (Chl a) concentration, and the composition of dissolved inorganic nitrogen were investigated along two transects in the estuary in 2010. In the surface waters, assimilation between May and November was suggested by high Chl a and δ15NO3 and supported by the mixing behavior of the nitrate and δ15NO3. From February to November, the mean nitrate content in the deep waters gradually increased (from ∼8 to ∼15 μmol l-1), whereas the mean δ15NO3 decreased (from ∼2‰ to ∼-2‰). Particularly in November, most of the δ15NO3 values in the deep waters were negative (∼-5‰ -0‰, which is much lower than the ∼3‰ riverine input from δ15NO3), indicating that most of the nitrates in the deep water were newly regenerated from nitrification rather than originating from riverine input. Additionally, the mean ammonium abruptly increased (from ∼2 to ∼20 μmol l-1) in the deep waters during November when the δ15NO3 values were negative, whereas in August, high Chl a values were observed in the deep waters. These results indicate that remineralization and nitrification occurred in the deep waters of the Changjiang River estuary, implying that regenerated
Pei, S.; Ye, S.; Laws, E. A.
In this study, primary productivities of phytoplankton in the areas of Liaodong Bay and Liaohe River Delta, China were investigated with chlorophyll contents and components, nutrient dynamics and all related environment parameters in July, 2013. Water samples collected from 14 typical sites were incubated under in situ or simulated in situ conditions by the 14C tracer method. Surface chl-a concentration in the coastal zone of Liaodong Bay ranged from 2.16 to 19.85 mg·m-3, and the corresponding primary productivity of particulate organic carbon (POC) ranged from 26.82 to 204.91 mg·m-3·h-1. Although both our chl-a and primary productivity measurements reveal significant spatial variability across the Liaodong Bay, the release rates of dissolved organic carbon (DOC) from phytoplankton cells into seawater accounts for 4.94±1.44% of the primary productivity of total organic carbon (TOC). Furthermore, the mean and standard deviation of photosynthetic assimilation numbers were 11.65±2.33 (range = 8.78 to 14.63; n=6) with specific maxima in two sites where transparency was better than others, comparatively. In the Liaohe River Delta, it is observed that chl-a concentration and the primary productivity of POC declined from 11.20 mg·m-3 and 89.03 mg·m-3·h-1 to be 1.54 mg·m-3 and 13.22 mg·m-3·h-1, separately, corresponding to the increasing of salinity from 1.0 to be 6.7 in the area dominated by the salinity gradient. The maxima primary productivity of TOC in the river (99.74 mg·m-3·h-1) was about ten times higher than the minima primary productivity (9.73 mg·m-3·h-1) in the coastal area of Liaodong Bay, probably because of the significant variation of nutrient dynamics, suspended particulate matter and transparency along the river discharge. The percentage of DOC release from phytoplankton cell in the river delta area was approximately 13.71±3.62%, much higher than that in the coastal area of Liaodong Bay. The possible effect of phytoplankton community on the
Zou, Hui; Zou, Zhihong; Wang, Xiaojing
The increase and the complexity of data caused by the uncertain environment is today’s reality. In order to identify water quality effectively and reliably, this paper presents a modified fast clustering algorithm for water quality analysis. The algorithm has adopted a varying weights K-means cluster algorithm to analyze water monitoring data. The varying weights scheme was the best weighting indicator selected by a modified indicator weight self-adjustment algorithm based on K-means, which is named MIWAS-K-means. The new clustering algorithm avoids the margin of the iteration not being calculated in some cases. With the fast clustering analysis, we can identify the quality of water samples. The algorithm is applied in water quality analysis of the Haihe River (China) data obtained by the monitoring network over a period of eight years (2006–2013) with four indicators at seven different sites (2078 samples). Both the theoretical and simulated results demonstrate that the algorithm is efficient and reliable for water quality analysis of the Haihe River. In addition, the algorithm can be applied to more complex data matrices with high dimensionality. PMID:26569283
Feng, X. Q.; Zhang, G. X.; Xu, Y. Jun
Zhalong National Nature Preserve is a large wetland reserve on the Songnen Plain in Northeast China. Wetlands in the preserve play a key role in maintaining regional ecosystem function and integrity. Global climate change and intensified anthropogenic activities in the region have raised great concerns over the change of natural flow regime, wetland degradation and losses. In this study, two key hydrologic components in the preserve, open water area and storage, as well as their variations during the period 1985-2006 were investigated with a spatially-distributed hydrologic modeling system, SWAT. A wetland module was incorporated into the SWAT model to represent hydrological linkages between the wetland and adjacent upland areas. The modified modeling system was calibrated with streamflow measurements from 1987 to 1989, in a Nash efficiency coefficient (Ens) of 0.86, and was validated for the period 2005-2006, in an Ens of 0.66. In the past 20 yr, open water area in the Zhalong Wetland fluctuated from approximately 200 km2 to 1145 km2 with a rapid decreasing trend through the early 2000s. Consequently, open water storage in the preserve decreased largely, especially in the dry seasons. The situation changed following the implementation of a river diversion in 2001. Overall, the modeling yielded plausible estimates of hydrologic changes in this large wetland reserve, building a foundation for assessing ecological water requirements and developing strategies and plans for water resources management within the river basin.
Feng, X. Q.; Zhang, G. X.; Xu, Y. Jun
Zhalong National Nature Preserve is a large wetland reserve on the Songnen Plain in Northeast China. Wetlands in the preserve play a key role in maintaining regional ecosystem function and integrity. Global climate change and intensified anthropogenic activities in the region have raised great concerns over the change of natural flow regime, wetland degradation and loss. In this study, two key hydrologic components in the preserve, water surface area and water volume, as well as their variations during the period 1985-2006, were investigated with a spatially-distributed hydrologic modeling system (SWAT). A wetland module was incorporated into the SWAT model to represent hydrological linkages between the wetland and adjacent upland areas. The modified modeling system was calibrated with streamflow measurements from 1987 to 1989 and was validated for the period 2005-2006. The calibration achieved a Nash efficiency coefficient (Ens) of 0.86, and the validation yielded an Ens of 0.66. In the past 20 yr, water surface area in the Zhalong wetland fluctuated from approximately 200 km2 to 1145 km2 with a rapid decreasing trend through the early 2000s. Consequently, water volume decreased largely in the preserve, especially in the dry seasons. The situation changed following the implementation of a river diversion in 2001. Overall, the modeling yielded plausible estimates of hydrologic changes in this large wetland reserve, building a foundation for assessing ecological water requirements and developing strategies and plans for future water resources management within the river basin.
Yuan, Zhongying; Lu, Weiyuan; Xu, Yuxin; Cao, Jianping
Background Cryptosporidium spp. is prevalent globally, pigs are an important Cryptosporidium reservoir. In China, little data regarding rates of Cryptosporidium infections in pigs are available. The present study was therefore aimed at characterizing the distribution of Cryptosporidium species in pigs from two different cities, Shaoxing and Shanghai, from the Yangtze River delta. Methodology/Principal Findings Nested PCR to amplify the 18S rRNA locus on DNA extracted from fecal samples (n = 94) revealed the positive rate of Cryptosporidium in pigs from two cities was approximately 17.0%. The positive rates in Shanghai and Shaoxing were 14.3% and 25.0% respectively. Amplified sequences were verified by sequencing. The identified strain belonged to the C. pig genotype II using BLAST analysis in the NCBI database. Conclusion/Significance Our finding of Cryptosporidium pig genotype II in pigs in the Yangtze River delta area suggests that pig farms in this region must be considered a public health threat and proper control measures be introduced. PMID:21677776
Zou, Hui; Zou, Zhihong; Wang, Xiaojing
The increase and the complexity of data caused by the uncertain environment is today's reality. In order to identify water quality effectively and reliably, this paper presents a modified fast clustering algorithm for water quality analysis. The algorithm has adopted a varying weights K-means cluster algorithm to analyze water monitoring data. The varying weights scheme was the best weighting indicator selected by a modified indicator weight self-adjustment algorithm based on K-means, which is named MIWAS-K-means. The new clustering algorithm avoids the margin of the iteration not being calculated in some cases. With the fast clustering analysis, we can identify the quality of water samples. The algorithm is applied in water quality analysis of the Haihe River (China) data obtained by the monitoring network over a period of eight years (2006-2013) with four indicators at seven different sites (2078 samples). Both the theoretical and simulated results demonstrate that the algorithm is efficient and reliable for water quality analysis of the Haihe River. In addition, the algorithm can be applied to more complex data matrices with high dimensionality. PMID:26569283
Gong, Yao; Yu, Zhigang; Yao, Qingzhen; Chen, Hongtao; Mi, Tiezhu; Tan, Jiaqiang
The rapid growth of the economy in China has caused dramatic growth in the industrial and agricultural development in the Yellow River (YR) watershed. The hydrology of the YR has changed dramatically due to the climate changes and water management practices, which have resulted in a great variation in the fluxes of riverine nutrients carried by the YR. To study these changes dissolved nutrients in the YR were measured monthly at Lijin station in the downstream region of the YR from 2002 to 2004. This study provides detailed information on the nutrient status for the relevant studies in the lower YR and the Bohai Sea. The YR was enriched in nitrate (average 314 μmol·L−1) with a lower concentration of dissolved silicate (average 131 μmol·L−1) and relatively low dissolved phosphate (average 0.35 μmol·L−1). Nutrient concentrations exhibited substantial seasonal and yearly variations. The annual fluxes of dissolved inorganic nitrogen, phosphate, and silicate in 2004 were 5.3, 2.5, and 4.2 times those in 2002, respectively, primarily due to the increase in river discharge. The relative contributions of nutrient inputs to nitrogen in the YR were: wastewater > fertilizer > atmospheric deposition > soil; while to phosphorus were: wastewater > fertilizer > soil > atmospheric deposition. The ratios of N, P and Si suggest that the YR at Lijin is strongly P-limited with respect to potential phytoplankton growth. PMID:26287226
Chen, Xiaoyan; Gao, Huiwang; Yao, Xiaohong; Chen, Zhenhua; Fang, Hongda; Ye, Shufeng
Marine ecosystem is a complex nonlinear system. However, ecosystem health assessment conventionally builds on a linear superposition of changes in ecosystem components and probably fails to evaluate nonlinear interactions among various components. To better reflect the intrinsic interactions and their impacts on ecosystem health, an ecosystem coordination index, defined as the matching level of ecosystem structure/services, is proposed and incorporated into the ecosystem health index for a systematic diagnosis in the Pearl River Estuary, China. The analysis results show that the ecosystem health index over the last three decades decreased from 0.91 to 0.50, indicating deteriorating from healthy to unhealthy status. The health index is 3–16% lower than that calculated using the common method without considering ecosystem coordination. Ecosystem health degradation in the Pearl River Estuary manifested as significant decreases in structure/services and somewhat mismatching among them. Overall, the introduction of coordination in ecosystem health assessment could improve the understanding of the mechanism of marine ecosystem change and facilitate effective restoration of ecosystem health. PMID:23894670
Xu, Xibao; Tan, Yan; Chen, Shuang; Yang, Guishan; Su, Weizhong
Carbon reduction at the household level is an integral part of carbon mitigation. This study analyses the characteristics, effects, contributing factors and policies for urban household carbon emissions in the Yangtze River Delta of China. Primary data was collected through structured questionnaire surveys in three cities in the region – Nanjing, Ningbo, and Changzhou in 2011. The survey data was first used to estimate the magnitude of household carbon emissions in different urban contexts. It then examined how, and to what extent, each set of demographic, economic, behavioral/cognitive and spatial factors influence carbon emissions at the household level. The average of urban household carbon emissions in the region was estimated to be 5.96 tonnes CO2 in 2010. Energy consumption, daily commuting, garbage disposal and long-distance travel accounted for 51.2%, 21.3%, 16.0% and 11.5% of the total emission, respectively. Regulating rapidly growing car-holdings of urban households, stabilizing population growth, and transiting residents’ low-carbon awareness to household behavior in energy saving and other spheres of consumption in the context of rapid population aging and the growing middle income class are suggested as critical measures for carbon mitigation among urban households in the Yangtze River Delta. PMID:25884853
Song, Wei; Zhang, Ying
The Heihe River Basin (HRB) is the second largest inland river basin in the arid region of northwestern China. An agricultural oasis is a typical landscape in arid regions providing precious fertile soil, living space and ecological services. The agricultural oasis change has been one of the key issues in sustainable development in recent decades. In this paper, we examined the changes in the agricultural oasis in HRB and analyzed the socio-economic and climatic driving forces behind them. It was found that the agricultural oasis in HRB expanded by 25.11% and 14.82% during the periods of 1986-2000 and 2000-2011, respectively. Most of the newly added agricultural oases in HRB were converted from grassland (40.94%) and unused land (40.22%). The expansion in the agricultural oasis mainly occurred in the middle reaches of HRB, particularly in the counties of Shandan, Minle, Jinta and Jiuquan city. Changes in the rural labor force, annual temperature and precipitation have significant positive effects on agricultural oasis changes, while the ratio of irrigated agricultural oases has significant negative effects on agricultural oasis changes. The agricultural oasis expansion in HRB is the combined effect of human activity and climate change.
Zhang, Honghui; Zeng, Yongnian; Zou, Bin; Xiao, Pengfeng; Hu, Deyong; Peng, Jianchao
This paper analyzes and simulates the land use changes in the Pearl River Delta, China, using Longgang City as a case study. The region has pioneered the nation in economic development and urbanization process. Tremendous land use changes have been witnessed since the economic reform in 1978. Land use changes are analyzed and simulated by using stochastic cellular automata model, land use trajectories analysis, spatial indices and multi-temporal TM images of Longgang City (TM1987, TM1991, TM1995, TM1999, TM2003, TM2005) in order to understand how urbanization has transformed the non-urban land to urban land and estimate the consequent environment and ecological impacts in this region. The analysis and simulation results show that urban land continues to sprawl along road and fringe of towns, and concomitant to this development is the loss of agricultural land, orchards and fish ponds. This study provides new evidence with spatial details about the uneven land development in the Pearl River Delta.
Sun, Chen; Wu, Hongjuan
Animal husbandry is one of the major agricultural pollution sources in China. The Xiangyang Reach of the Han River Basin was used as a case study to identify pollutants from animal rearing. The gross amount of pollutants from livestock and poultry rearing in the Xiangyang Reach was estimated using two empirical models with different data sets. The pig, cattle, sheep, and poultry population in 2009 amounted to 2.6, 0.6, 0.5, and 39.2 million head, respectively. The total annual pollutant loads generated from the feces and urine of livestock and poultry were 270,400 t of chemical oxygen demand; 228,900 t of biochemical oxygen demand; 26,500 t of ammonia nitrogen; 16,500 t of total phosphorus; and 63,900 t of total nitrogen. Approximately 12% of these pollutant loads were estimated to enter the Han River through the watershed outlet. Animal breeding has been one of the main pollution sources in this area, followed by domestic sewage and industrial wastewater. Cattle produced the most pollution, with the heaviest pollution load in downtown Xiangyang City. Several recommendations are presented to control the pollution caused by livestock and poultry breeding. PMID:22766880
Fang, Shi-bo; Liu, Shi-liang; Gao, Zhiqiang
Natural Forest Conservation Program (NFCP) was established in China in 1998. As a nationwide engineering project, one of the most important tasks was to mandate conversion of marginal farmlands to forestland or grassland (reforestation or afforestation in farmlands) where topographical slope steepness was more than 25 degree. In order to quantitatively grade agriculture soil loss amount and assess spatio-temporal variation of soil erosion volume, as well as to guide the process of the conversion of farmlands to forest in upstream of Yangtze Rivers. The research analyzed how to calculate K, S, L, C and P factors of Universal Soil Loss Equation (USLE) on the base of considering terrain, climate and characters of agricultural soil using GIS technology. The methods can adapt to the variation terrain of the dry valley region in upstream of Yangtze Rivers. As believed the reforestation was a long-term engineering, the planning of reforest farmlands should be a temporal decision process, which should be considered that where should be afforested at once and where should afforested in abeyance on the basis of grading soil loss amount and the others conditions of farmland. Grading agricultural soil loss amount would be beneficial to program a feasible plan in the conversation of farmlands to forest.
Chen, Haiyang; Teng, Yanguo; Yue, Weifeng; Song, Liuting
Characterizing water quality and identifying potential pollution sources could greatly improve our knowledge about human impacts on the river ecosystem. In this study, fuzzy comprehensive assessment (FCA), pollution index (PI), principal component analysis (PCA), and absolute principal component score-multiple linear regression (APCS-MLR) were combined to obtain a deeper understanding of temporal-spatial characterization and sources of water pollution with a case study of the Jinjiang River, China. Measurement data were obtained with 17 water quality variables from 20 sampling sites in the December 2010 (withered water period) and June 2011 (high flow period). FCA and PI were used to comprehensively estimate the water quality variables and compare temporal-spatial variations, respectively. Rotated PCA and receptor model (APCS-MLR) revealed potential pollution sources and their corresponding contributions. Application results showed that comprehensive application of various multivariate methods were effective for water quality assessment and management. In the withered water period, most sampling sites were assessed as low or moderate pollution with characteristics pollutants of permanganate index and total nitrogen (TN), whereas 90% sites were classified as high pollution in the high flow period with higher TN and total phosphorus. Agricultural non-point sources, industrial wastewater discharge, and domestic sewage were identified as major pollution sources. Apportionment results revealed that most variables were complicatedly influenced by industrial wastewater discharge and agricultural activities in withered water period and primarily dominated by agricultural runoff in high flow period. PMID:23737126
Wu, Wei; Xu, Zongxue; Zhan, Chesheng; Yin, Xuwang; Yu, Songyan
Due to the rapid growth of the population and the development of economies in the Guanzhong district, central China, the river ecosystem is gradually deteriorating, which makes it important to assess the aquatic ecosystem health and take measures to restore the damaged ecosystem. An index of catchment ecosystem health has been developed to assist large-scale management of watersheds by providing an integrated measure of ecosystem health, including aquatic and terrestrial ecosystem. Most researches focus on aquatic ecosystem or terrestrial ecosystem, but little research integrates both of them to assess the catchment ecosystem health. In this paper, we combine these two aspects into catchment ecosystem health. Ecosystem indicators derived from field samples and modeling are identified to integrate into ecosystem health. These included indicators of ecological landscape pattern (based on normalized difference vegetation index (NDVI), vegetation cover, dominance index, Shannon's diversity index, Shannon's evenness index, and fragmentation index), hydrology regime (based on 33 hydrological parameters), physical form condition (based on substrate, habitat complexity, velocity/depth regimes, bank stability, channel alteration), water quality (based on electrical conductivity (Cond), dissolved oxygen (DO), NH3_N, total nitrogen (TN), total phosphorus (TP), chemical oxygen demand-permanganate (CODMn)), and biological quality (based on fish abundance). The index of ecosystem health is applied in the Guanzhong district, and the ecosystem health was fair. The ecosystem health in the upstream to Linjiacun (U-L) and Linjiacun to Weijiabao (L-W) reaches was in good situation, while that in Weijiabao to Xianyang (W-X), Xianyang-Weijiabao (X-W), and Weijiabao to Tongguan (W-T) reaches was in fair situation. There is a trend that the ecosystem health in the upstream was better than that in the downstream. The ecosystem health assessment is expected to play a key role in future
Xie, Rongrong; Pang, Yong; Li, Zhe; Zhang, Ninghong; Hu, Fenjuan
Eco-compensation is a multi-disciplinary topic. There is no consensus on the issue of river eco-compensation across districts. Although policies regarding river eco-compensation have been issued in China since 2008, due to the high cost, eco-compensation has not been well implemented in the Taihu pilot region. Therefore, a simplified method based solely on water quality (both water quality and water volume included in the Taihu method) was proposed for North Jiangsu province (NJP). However, the formula was flawed and it led to payments being too low. Three problems need to be solved: (1) how to specify the eco-compensation areas; (2) how to test a reasonable eco-compensation model and (3) how to determine the compensation criterion. Solving these issues is already a priority. In this paper, three potential solutions surrounding eco-compensation are discussed: (1) three principles for selecting the representative eco-compensation areas are suggested; (2) the compensation calculation method based on contaminant flux above the ultra standard is revised and (3) a compensation criterion model based on the treatment costs of sewage is proposed. In the NJP case in 2009, the average eco-compensation criterion for chemical oxygen demand (COD) is 2,000 Chinese Yuan (CNY) per ton and ammonia nitrogen (NH4-N) and total phosphorus (TP) are 8,000 CNY and 80,000 CNY per ton, respectively. Five districts needed to be compensated. The payments in the revised scheme were 4.15-586 million CNY, which were 16-48 times greater than that in the draft method. The new method can provide an important template for managers when drafting river eco-compensation schemes.
Cheng, Aifang; Feng, Qi; Fu, Guobin; Zhang, Jiankai; Li, Zongxing; Hu, Meng; Wang, Gang
Changes in rainfall extremes pose a serious and additional threat to water resources planning and management, natural and artificial oasis stability, and sustainable development in the fragile ecosystems of arid inland river basins. In this study, the trend and temporal variation of extreme precipitation are analyzed using daily precipitation datasets at 11 stations over the arid inland Heihe River basin in Northwest China from 1960 to 2011. Eight indices of extreme precipitation are studied. The results show statistically significant and large-magnitude increasing and decreasing trends for most indices, primarily in the Qilian Mountains and eastern Hexi Corridor. More frequent and intense rainfall extremes have occurred in the southern part of the desert area than in the northern portion. In general, the temporal variation in precipitation extremes has changed throughout the basin. Wet day precipitation and heavy precipitation days show statistically significant linear increasing trends and step changes in the Qilian Mountains and Hexi Corridor. Consecutive dry days have decreased obviously in the region in most years after approximately the late 1980s, but meanwhile very long dry spells have increased, especially in the Hexi Corridor. The probability density function indicates that very long wet spells have increased in the QilianMountains. The East Asian summer monsoon index and western Pacific subtropical high intensity index possess strong and significant negative and positive correlations with rainfall extremes, respectively. Changes in land surface characteristics and the increase in water vapor in the wet season have also contributed to the changes in precipitation extremes over the river basin.
Natural disasters have profound effects on community security and economic damage of China's Hubei province. In June 1st, 2015, a cruise ship, Easter Star, capsized on Yangtze River in Hubei province with 442 died. What reason gives rise to such strong convection causing ship sunk? Based on the wind disasters of Hubei province happened in 1963-2015, this study analyzes their features bytime-series regression, and correlates them to global El Niño/Southern Oscillation (ENSO) events. The compared results demonstrated that the wind disasters shown an increasing tendency. There are two peaks corresponding to the strongest ENSO peaks during the past 50 years; each peak lasts two-three years. The facts demonstrated an essential linear relation between the ENSO phenomena and wind disasters in Hubei province. 2015 Easter Star capsized happened at current El Niño event in 2014-2015. We also observed that the historical wind disasters appeared in seasonal variation. Over 90% events concentrated in spring and summer; very few events happened in autumn and winter. Moreover, the disasters depend on the geographic conditions. Most disasters concentrated in four zones, named as Xingshan-Baokang, Xuanen, Wufeng-Yichang, Jingzhou-Gongan, in which Xingshan and Changyang are the two most density of zones. Yangtze River provides an air flowing conduct for strong convective winds. It can be concluded that the strong convection causing 2015 Easter Star capsized is related to current global ENSO phenomenon.Keywords: ENSO, wind disaster, time-series regression analysis, Easter Star, Yangtze River, Hubei Province,
Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing
The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale. PMID:26544070
Zeng, Xiaofan; Zhao, Na; Sun, Huaiwei; Ye, Lei; Zhai, Jianqing
The comprehensive assessment of climatic and hydrological droughts in terms of their temporal and spatial evolutions is very important for water resources management and social development in the basin scale. To study the spatial and temporal changes of climatic and hydrological droughts and the relationships between them, the SPEI and SDI are adopted to assess the changes and the correlations of climatic and hydrological droughts by selecting the Jialing River basin, China as the research area. The SPEI and SDI at different time scales are assessed both at the entire Jialing River basin and at the regional levels of the three sub basins. The results show that the SPEI and SDI are very suitable for assessing the changes and relationships of climatic and hydrological droughts in large basins. Based on the assessment, for the Jialing River basin, climatic and hydrological droughts have the increasing tendency during recent several decades, and the increasing trend of climatic droughts is significant or extremely significant in the western and northern basin, while hydrological drought has a less significant increasing trend. Additionally, climatic and hydrological droughts tend to increase in the next few years. The results also show that on short time scales, climatic droughts have one or two months lag impact on hydrological droughts in the north-west area of the basin, and have one month lag impact in south-east area of the basin. The assessment of climatic and hydrological droughts based on the SPEI and SDI could be very useful for water resources management and climate change adaptation at large basin scale. PMID:26544070
Sun, Cui-Ci; Wang, You-Shao; Li, Qian P.; Yue, Wei-Zhong; Wang, Yu-Tu; Sun, Fu-Lin; Peng, Ya-Lan
Distribution of Transparent Exopolymer Particles (TEP) in the Pearl River estuary, China, was investigated during two cruises in August 2009 and January 2010. TEPcolor concentrations were 521.5-1727.4 μg Xeq.L-1 (μg Gum Xanthan equivalent liter-1) in August 2009 and 88.7-1586.9 μg Xeq.L-1 in January 2010, respectively. The size of TEP generally increased in the seaward along the longitudinal section with the dominant size of 2-40 μm during the cruises. Experimental work suggested that both concentration and size of TEP increased with Ca2+ concentration (from 0.8 mmol L-1 to 10 mmol L-1). In the field study, Ca2+ concentration had a positive correlation with TEPcolor concentration in the surface layer with salinity <16. Decrease of TEP concentration seaward from intermediary salinity was partly due to dilution of seawater as well as enhanced aggregation and sedimentation of TEP via increasing divalent cation concentration. TEP concentration and turbidity maximum coexisted at the tip of salt wedge in the bottom layer during the wet season, and positive correlation between TEP and turbidity was observed in the winter. Relationships between TEP and turbidity suggested the important contribution of TEP aggregation to flocculation and sedimentation of particles in estuaries. Different pattern of TEP during two cruises can be attributed to physical process (i.e., mixing type) in estuaries. These findings indicated that formation and distribution of TEP were largely influenced by interaction between physical and biogeochemical processes in the Pearl River estuary. A conceptual model for TEP formation and distribution in the Pearl River estuary was developed.
Gai, Lingtong; Baartman, Jantiene E. M.; Mendoza-Carranza, Manuel; Wang, Fei; Ritsema, Coen J.; Geissen, Violette
Flood hazard has become a growing concern in the Wei River Basin in China due to the extensive damage to private and public property under the pressure of extreme meteorological events and human intervention in the river basin. A better understanding of the influence of topographic, climatic and especially anthropogenic factors on hydrological discharge and flooding are important for flood regime and water resources management. This study is aiming at answering the questions why, where, when, and how flooding occurs. While most studies focus on single flood events, we aimed at unravelling a multitude of factors contributing to flooding over a decadal timespan. To be able to do this, we used conditional inference tree analysis, a promising method not often applied in hydrological studies. This method allows to rank all the influencing factors by its contribution to the occurrence of flooding therefore to identify the most important ones and spatially important subcatchments leading to flooding on both yearly and monthly bases in the basin. Dam construction period was identified as the most important factor (why) affecting flooding, followed by the elevation of the river outlet. The subcatchment farthest upstream in the basin (where) contributed the most to the discharge at the downstream floodplain. We then analyzed the impact of the periods of dam construction on the precipitation-discharge relationship using cross-correlation and double mass curves analysis, respectively. The results showed a smaller effect of dam construction on the time lags (when) between precipitation and discharge than on the effect of reducing the quantity of discharge (how).
Wu, Pan; Qin, Boqiang; Yu, Ge; Deng, Jianming; Zhou, Jian
To explore the linkage of phosphorus (P), nitrogen (N) and phytoplankton during the summer and winter in the inflow rivers of the Taihu Basin, China, 51 main rivers were investigated in 2013 and 2014. The results showed that high P and N input deteriorated the water quality, and P primarily limited Chlorophyll a concentrations. Diatoms, green algae, and cyanobacteria were the dominant phyla, totaling 29 and 41 species in summer and winter, respectively. Total P negatively affected the phytoplankton diversity during summer and had a stronger positive relationship with richness than total N during winter. The P level restricted the biomass of dominant algae, and turbidity had a greater interaction with cyanobacteria. This study suggests that P drives the phytoplankton assemblages under N-rich environments in the inflow rivers during summer and winter, indicating the need for nutrient reduction and further monitoring of the rivers to improve the water ecology. PMID:27329063
Chen, Wei; Qi, Shihua; Peng, Fei; Qu, Chengkai; Zhang, Yuan; Xing, Xinli; Zhang, Jiaquan
Organochlorine pesticides (OCPs) are a sub-group of persistent organic pollutants (POPs), which have raised the concerns from researchers all around the world for several decades. But very little research has been conducted on POPs in the arid zone of Northwest China. More than 100 soil and sediment samples were collected from Kaidu-Peacock River of Xinjiang, Northwest of China, to investigate the organochlorine pesticides (OCPs) in this region analysed by the gas chromatograph equipped with a mass selective detector (GC-MSD). Our pre-study in 2006 (Chen et al. 2011) in the same region, showed that OCPs except o,p'-DDT were detected in sediments from the Peacock River. Similar results were found in the whole river catchment in this investigation. DDTs, HCHs, chlordanes and endosulfans were the dominant OCPs residual in the soil and sediments. This study confirmed that POPs, such as OCPs in this region were contributed to by both local emissions and long-term atmospheric transport and may pose risks to human health and the ecosystem. Chen, W., Jing, M., Bu, J., Ellis Burnet, J., Qi, S., Song, Q., Ke, Y., Miao, J., Liu, M. & Yang, C. (2011) Organochlorine pesticides in the surface water and sediments from the Peacock River Drainage Basin in Xinjiang, China: a study of an arid zone in Central Asia. Environmental Monitoring and Assessment, 177, 1-21.
Rumbaur, C.; Thevs, N.; Disse, M.; Ahlheim, M.; Brieden, A.; Cyffka, B.; Duethmann, D.; Feike, T.; Frör, O.; Gärtner, P.; Halik, Ü.; Hill, J.; Hinnenthal, M.; Keilholz, P.; Kleinschmit, B.; Krysanova, V.; Kuba, M.; Mader, S.; Menz, C.; Othmanli, H.; Pelz, S.; Schroeder, M.; Siew, T. F.; Stender, V.; Stahr, K.; Thomas, F. M.; Welp, M.; Wortmann, M.; Zhao, X.; Chen, X.; Jiang, T.; Luo, J.; Yimit, H.; Yu, R.; Zhang, X.; Zhao, C.
The Tarim River basin, located in Xinjiang, NW China, is the largest endorheic river basin in China and one of the largest in all of Central Asia. Due to the extremely arid climate, with an annual precipitation of less than 100 mm, the water supply along the Aksu and Tarim rivers solely depends on river water. This is linked to anthropogenic activities (e.g., agriculture) and natural and semi-natural ecosystems as both compete for water. The ongoing increase in water consumption by agriculture and other human activities in this region has been enhancing the competition for water between human needs and nature. Against this background, 11 German and 6 Chinese universities and research institutes have formed the consortium SuMaRiO (Sustainable Management of River Oases along the Tarim River; http://www.sumario.de), which aims to create a holistic picture of the availability of water resources in the Tarim River basin and the impacts on anthropogenic activities and natural ecosystems caused by the water distribution within the Tarim River basin. On the basis of the results from field studies and modeling approaches as well as from suggestions by the relevant regional stakeholders, a decision support tool (DST) will be implemented that will then assist stakeholders in balancing the competition for water, acknowledging the major external effects of water allocation to agriculture and to natural ecosystems. This consortium was formed in 2011 and is funded by the German Federal Ministry of Education and Research. As the data collection phase was finished this year, the paper presented here brings together the results from the fields from the disciplines of climate modeling, cryology, hydrology, agricultural sciences, ecology, geoinformatics, and social sciences in order to present a comprehensive picture of the effects of different water availability schemes on anthropogenic activities and natural ecosystems along the
Zang, C. F.; Liu, J.; van der Velde, M.; Kraxner, F.
In arid and semi-arid regions freshwater resources have become scarcer with increasing demands from socio-economic development and population growth. Until recently, water research and management in these has mainly focused on blue water but ignored green water. Here we report on spatial and temporal patterns of both blue and green water flows simulated by the Soil and Water Assessment Tool (SWAT) for the Heihe river basin, the second largest inland river basin in Northwest China. Calibration and validation at two hydrological stations show good performance of the SWAT model in modelling hydrological processes. The total green and blue water flows were 22.09 billion m3 in the 2000s for the Heihe river basin. Blue water flows are larger in upstream sub-basins than in downstream sub-basins mainly due to high precipitation and large areas of glaciers in upstream. Green water flows are distributed more homogeneously among different sub-basins. The green water coefficient was 88.0% in the 2000s for the entire river basin, varying from around 80-90% in up- and mid-stream sub-basins to above 95% in downstream sub-basins. This is much higher than reported green water coefficient in many other river basins. The spatial patterns of green water coefficient were closely linked to dominant land covers (e.g. glaciers in upstream and desert in downstream) and climate conditions (e.g. high precipitation in upstream and low precipitation in downstream). There are no clear consistent historical trends of change in green and blue water flows and green water coefficient at both the river basin and sub-basin levels. This study provides insights into green and blue water endowments for the entire Heihe river basin at sub-basin level. The results are helpful for formulating reasonable water policies to improve water resources management in the inland river basins of China.
Kissel, Catherine; Liu, Zhifei; Wandres, Camille; Liu, Qingsong
In order to use the magnetic properties of marine sediments as a tracer for past changes in the precipitation rate and in oceanic water masses transport and exchanges, it is critical to identify and to characterize the different sources of the detrital fraction among which the magnetic particles. This is of peculiar importance in marginal seas such as the South China Sea extending from about 25°N to the equator. Thanks to the Westpac project, we had access to a number of sediments collected in the deltas of the main rivers feeding the South China Sea. This is represented on the Asian continent by the Pearl river, the Red River, the Mekong river, by Malaysia, Sumatra and Borneo regions with minor rivers but also contributing to the South China Sea, and finally by Luzon and Taiwan. The geological formations contributing to the river sediment discharges are different from one catchment basin to another as well as the present climatic conditions. The magnetic analyses conducted on the samples are the low-field magnetic susceptibility, the ARM acquisition and decay, the IRM acquisition and decay, the back-field acquisition, the thermal demagnetization of 3-axes IRM, the hysteresis parameters, the FORC diagrams. The obtained parameters all together allow us to define the nature of the magnetic grains and their grain size distribution when magnetite is dominant. Some degree of variability is observed at the river mouths, illustrating different geological sources at the local/regional scale. As an average, it appears that the Southern basin of the South China Sea is surrounded by regions richer in high coercivity magnetic minerals than the northern basin. This mineral is identified as hematite while magnetite is more abundant in the north. These results are complementary to the clay mineral assemblages previously determined on the same samples. We'll give some example of how this knowledge allows us to interpret the paleo-marine records from the South China Sea in terms
Zhang, Zhaoyong; Juying, Li; Mamat, Zulpiya; QingFu, Ye
The current study focused on the Bortala River - a typical inland river located in an oasis of arid area in northwestern China. The sediment and soil samples were collected from the river and drainage basin. Results showed that: (1) the particle size of the sand fraction of the sediments was 78-697 µm, accounting for 78.82% of the total samples; the average concentrations of eight heavy metals fell within the concentration ranges recommended by the Secondary National Standard of China, while the maximum concentrations of Pb, Cd, and Hg exceeded these standards; (2) results from multivariate statistical analysis indicated that Cu, Ni, As, and Zn originated primarily from natural geological background, while Cd, Pb, Hg and Cr in the sediments originated from human activities; (3) results of the enrichment factor analysis and the geo-accumulation index evaluation showed that Cd, Hg, and Pb were present in the surface sediments of the river at low or partial serious pollution levels, while Zn, Cr, As, Ni, and Cu existed at zero or low pollution levels; (4) calculation of the potential ecological hazards index showed that among the eight tested heavy metals, Cd, Pb, Hg, and Cr were the main potential ecological risk factors, with relative contributions of 25.43%, 22.23%, 21.16%, and 14.87%, respectively; (5) the spatial distribution of the enrichment factors (EF(S)), the Geo-accumulation index (I(geo)), and the potential ecological risk coefficient (E(r)(i)) for eight heavy metals showed that there was a greater accumulation of heavy metals Pb, Cd, and Hg in the sediments of the central and eastern parts of the river. Results of this research can be a reference for the heavy metals pollution prevention, the harmony development of the ecology protection and the economy development of the oases of inland river basin of arid regions of China, Central Asia and also other parts of the world. PMID:26735186
Xiao, Xue; Zhao, Nan-Jing; Yuan, Jing; Ma, Ming-Jun; Fang, Li; Wang, Yin; Meng, De-Shuo; Yu, Yang; Tang, Jie; Zhang, Xiao-Ling; Dai, Yuan; Zhang, Yu-Jun; Liu, Jian-Guo; Liu, Wen-Qing
By means of field sampling and laboratory analysis, the content distribution characteristics of Cd, Cr, Cu, Ni, Pb and Zn in agricultural region soils of Huaihe basin in Anhui province were analyzed. Assessment of heavy metal pollutions was conducted using enrichment factor, geoaccumulation index and potential ecological risk index. The results showed that the average mass fraction of Cd and Cu was 0.113 5 and 22.09 mg x kg(-1) respectively in the study area soil, which were above the background values 0.097 and 20.4 mg x kg(-1) in Anhui Province. The average mass fraction of other four heavy metals did not exceed the average values of Anhui Province. The results of the evaluations from geoaccumulation index and ecological risk assessment discovered that Cd is the strongest pollution metal among six heavy metals in the study area soil. For some samples of the study soil, Cd was slight risk for the ecosystem. The ecosystem risks caused by the other five heavy metals were not obviously for the sampling points. The entire study area soils were mid integrated potential ecological risk. PMID:25269280
Liu, Tao; Huang, Chun Chang; Pang, Jiangli; Zha, Xiaochun; Zhou, Yali; Zhang, Yuzhu; Ji, Lin
Slackwater palaeoflood deposits (SWDs) were identified in a bedrock gorge in the upper reaches of the Hanjiang River of central China. The Hanjiang River is the longest tributary of the Yangtze River, one of the most flood-prone rivers in China, and the main source of water for the South-to-North Water Transfer Project (SNWTP). Three main loess-soil profiles with late Pleistocene and Holocene palaeoflood SWD bedsets were found. Palaeoflood SWDs identified interbedded in the loess-soil sequence of late Pleistocene and Holocene age within the cliff riverbanks were studied by field observations and laboratory analysis, including particle-size distribution and Optically Stimulated Luminescence (OSL) dating. At least eight extreme flood events documented by palaeoflood SWDs occurred in the Wufeng reaches of the upper Hanjiang River. The discharge estimation associated with palaeoflood SWDs, indicates that the minimum flood peak discharges of these flood episodes range from 42,220 to 63,400 m3/s. The SWDs were OSL dated to between 12,600-12,400, 4200-4000, 3200-2800 and 1900-1700 a BP and these dates were corroborated with pottery remains retrieved from the profiles and dated by archaeological methods. These periods of increased flood magnitude coincide with contemporaneous global climatic events dated to 12,500, 4200, 3100 and 1900 a BP worldwide. These findings are of great significance in understanding the interactions between hydrological systems and climatic change in monsoonal zones.
Luo, X.J.; Chen, S.J.; Mai, B.X.; Sheng, G.Y.; Fu, J.M.; Zeng, E.Y.
Polycyclic aromatic hydrocarbons (PAHs) were measured in 59 surface sediments from rivers in the Pearl River Delta and the northern continental shelf of the South China Sea. Total PAH concentrations varied from 138 to 6,793 ng/g dry weight. The sources of PAH inputs to sediments in the Pearl River Delta were qualitatively and quantitatively determined by diagnostic ratios and principal components analysis with multiple linear regression. The results showed that on average coal and wood combustion, petroleum spills, vehicle emissions, and nature sources contributed 36%, 27%, 25%, and 12% of total PAHs, respectively. Coal and biomass combustion was the main source of PAHs in sediments of the South China Sea, whereas petroleum combustion was the main source of pyrolytic PAHs in riverine and estuarine sediments of the Pearl River Delta. Perylene was formed in situ in river sediments and then transported to coastal areas along with other PAHs. The relative abundance of perylene from five-ring PAHs can be used to estimate the contribution of riverine-discharged PAHs to coastal sediments.
Gong, Jian; Ran, Yong; Chen, Diyun; Yang, Yu; Ma, Xiaoxuan
The occurrence and environmental risk of endocrine-disrupting chemicals was investigated in the surface water samples of the Zhujiang and Dongjiang rivers, Pearl River Delta (PRD) of South China. Thirty surface water samples were collected in the dry season and analyzed by using an MSTFA derivation and a GC-MS-SIM method. Concentrations of biphenol A (BPA) ranged from 43.5 to 639.1 ng L( - 1), and concentrations of estrone (E1) and 17beta-estradiol (E2) ranged from <1.5 to 8.2 ng L( - 1) and from <1.1 to 1.7 ng L( - 1), respectively. The spatial distribution of these chemicals was related to the discharge of domestic and industrial wastewater along the rivers. The highly significant correlation among BPA, E1, and dissolved organic carbon (DOC) might be related to their same contamination source and/or their association with colloidal organic carbon of DOC in the river samples. Compared with other studied rivers in the world, the estrogenic contamination in the investigated rivers was high for BPA and moderate for E1. As the average estrogenic activity in E2 activity equivalent (E2eq; 1.16 ng E2eq L( - 1)) for the target BAP, E1, and E2 combined with those for nonyphenol and octylphenol, which were previously reported, exceeds documented effect levels in the investigated river waters for some aquatic species, they may pose a high risk to the local aquatic organisms. PMID:18670899
Xiao, Shengchun; Xiao, Honglang; Peng, Xiaomei; Song, Xiang
Changes in the landscape structure of terminal lakes and wetlands along inland rivers in arid areas are determined by the water balance in the river basins under the impacts of climate change and human activities. Studying the evolution of these landscapes and the mechanisms driving these changes is critical to the sustainable development of river basins. The terminal lakes and wetlands along the lower reaches of the Heihe River, an inland river in arid northwestern China, can be grouped into three types: runoff-recharged, groundwater-recharged, and precipitation-recharged. These water-recharge characteristics determine the degree to which the landscape structure of a terminal lake or wetland is impacted by climate change and human activities. An analysis of seven remote-sensing and hydroclimatic data sets for the Heihe River basin during the last 50 years indicates that hydrological changes in the basin caused by regional human activities were the primary drivers of the observed changes in the spatial and temporal landscape-structure patterns of the terminal lakes and wetlands of the Heihe River. In this warm, dry climatic context, the lakes and wetlands gradually evolved toward and maintained a landscape dominated by saline-alkaline lands and grasslands. PMID:25427825
Du, Zhiqiang; Linghu, Bin; Ling, Feng; Li, Wenbo; Tian, Weidong; Wang, Hailei; Gui, Yuanmiao; Sun, Bingyu; Zhang, Xiaoming
The Qingjiang River Basin, which is 423 km long in the Hubei province, China, is the first large tributary of the Yangtze River below the Three Gorges. The Qingjiang River Basin surface water area monitoring plays an important role in the water resource management strategy and regular monitoring management of the Yangtze River watershed. Hydropower cascade exploitation, which started in 1987, has formed three reservoirs including the Geheyan reservoir, the Gaobazhou reservoir, and the Shuibuya reservoir in the midstream and downstream of the Qingjiang River Basin. They have made a great impact on surface water area changes of the Qingjiang River Basin and need to be taken into account. We monitor the Qingjiang River Basin surface water area changes from 1973 to 2010. Ten scenes from the Multispectral Scanner System (MSS), seven scenes from the Thematic Mapper (TM), and two scenes from the Enhanced Thematic Mapper Plus (ETM+) remote sensing data of Landsat satellites, the normalized different water index (NDWI), the modified NDWI (MNDWI), and Otsu image segmentation method were employed to quantitatively estimate the Qingjiang River Basin surface water area in the 1970s, 1980s, 1990s, and 2000s, respectively. The results indicate that the surface water area of the Qingjiang River Basin shows a growing trend with the hydropower cascade development from the 1980s to the first decade of the 21st century. The study concluded the significance of human activities impact on surface water spatiotemporal distribution. Surface water accretion is significant in most parts of the Qingjiang River Basin and might be related to the constructed cascade hydropower dams.
Kuo, Yi-Ming; liu, Wenwen
Algal bloom was occurred every year in the down stream of the Han River in recent five years. The operation of the Middle Route of China's South-to-North Water Transfer (MSNW) Project may affect the hydrological condition and self-purification of water body in the down and middle streams of the Han River, trigger algal bloom, and elevate the difficulty in the treatment of water pollutants, which is a crucial issue involved in ecology, environment, and economy. In this study, the monthly water samples were collected from the middle and down streams of Han River from July 2014 to December 2015. Factor Analysis and Cluster Analysis were applied to identify major pollution types and areas and determine the reasons influencing the variations of water quality in the down and middle streams of the Han River. The results show that whole monitoring period can be divided into three periods as different pollution levels. The factor analysis distinguishes three pollution types (inorganic pollution, organic pollution, and agricultural pollution) and thier contributions on Han River water quality in dry and wet seasons. Industrial areas are influenced by inorganic pollution and cultivated lands are influenced by agricultural pollution. The water quality in wet season is significantly affected by flow rate, which was sometimes controlled by two projects. The heavy polluted water may be diluted by high flow volume.
Li, X.; Che, T.; Li, H.; Jin, R.; Liu, S.; Huang, C.
We provide an overview of a high mountain river basin observing system in the Qilian Mountains of China. Mountain cryosphere is very sensitive to climate change, however, monitoring and modeling of cryospheric process and its interaction with hydrology and ecology needs to be further strengthened. We establish a multi-scale high mountain river basin observing system in the upstream area of the Heihe River Basin, Qilian Mountains of China. This system consists of flux towers on alpine tundra, alpine meadow and alpine steppes, a network of automatic meteorological stations, a wireless sensor network of soil moisture, soil temperature, snow depth, and precipitation, and two super observatories for monitoring snow and frozen soil, respectively. Super-high resolution (1 meter) DEMs of four experiment sub-watersheds (each about 20-40 km2) within this river basin were obtained via airborne LiDAR remote sensing.We introduce the data obtained since 2012 and present some preliminary modeling and data assimilation results. The results show that runoff, precipitation, snowmelt, and glacier melt keep increasing in the upstream area of the Heihe River Basin due to a warming climate. The ratio of snowmelt in total runoff has increased and the onset of snowmelt has gone ahead. The contribution of glacier melt to total runoff has almost doubled in the past decade. Frozen soil melt advances in time as well, and it may also contributes to the increase of the portion of baseflow in total runoff.This observatory has joined the International Network for Alpine Research Catchment Hydrology (NARCH) and will work as a unique site to monitor cryospheric and hydroclimatological changes in very high mountains.
Chen, Yongshan S; Yu, Shen; Hong, Youwei W; Lin, Qiaoying Y; Li, Hongbo B
Pharmaceutical compounds were increasingly detected in environmental matrices but little is known whether these compounds would transport to coastal zones via watersheds. Three typical tidal rivers in southeastern China were selected and 15 surface sediment samples (0-10 cm) were collected along a 50-km tidal section of each river. Surface sediment samples were frozen-drying and then extracted for pharmaceutical compounds by an accelerated solvent extraction system. The pharmaceutical compounds in extracts were scanned using a high-performance liquid chromatography/tandern mass spectrometry (HPLC-MS/MS). Three hundred and thirty compounds from nine pharmaceutical groups were detected with signal-to-noise above three (detectable level) in the surface sediments, of which 186 compounds were with a signal-to-noise above ten (measurable level). Of all, 291 and 80 compounds were detectable and measurable in all the three rivers, respectively. The Jiulong River showed a high load of pharmaceutical compounds in surface sediment than other two rivers. Of the nine pharmaceutical groups, the antihistamines and detoxification group and anti-infective drug group contributed five dominant compounds in the surface sediments in all the three rivers. Natures of pharmaceutical compounds rather than the sediment properties (pH, EC, and total carbon content) might influence their residues. The incredible number and intensity of pharmaceutical residues were detected in tidal surface sediments of the three rivers indicating that the pharmaceutical contamination should be strongly considered in China. Source identification and eco-toxicity assessment should be taken into account in the future study. Therapeutic medicine managements need to be strictly improved at a watershed scale to reduce loads of pharmaceuticals into aquatic ecosystems. PMID:23764981
Xu, Peng; Zhang, Yisheng; Gong, Weiwei; Hou, Xikang; Kroeze, Carolien; Gao, Wei; Luan, Shengji
In an agricultural county like China, agricultural fertilizers are the source of ammonia (NH3) emissions. However, the spatial variability in NH3 emissions is large, and the associated uncertainties affect the reliability of total NH3 emission estimates. In this study, an inventory is presented for NH3 emissions from China's agricultural fertilizer application at the city-level, and on a 1 × 1 km grid for croplands in 2010. We present NH3 emissions by source, the temporal and spatial patterns, and the associated uncertainties. The inventory is based on high-resolution activity data, regional emission factors (EFs) and related parameters that are derived from local studies. We compare our emissions estimates with previous inventories from EDGAR and other studies. The total NH3 emissions from China's agricultural fertilizer is 10.7 (8.9-12.3) TgNH3·yr-1. Livestock manure spreading contributes 47.5% to the total emissions, and synthetic fertilizer use by 41.9%. Rural excrement (5.0%) and cake fertilizer (5.5%) are relatively small sources. The spatial pattern of NH3 emissions from China's agricultural fertilizer were primarily concentrated in the North China Plain, the Songliao Plain, the Huaihe River Basin, the Middle-Lower Yangtze Plain, the Pearl River Delta Plain, the Sichuan Basin, the Tarim basin and the Leizhou Peninsula. Approximately 50% of the emissions are from only 76 cities. Our temporal analysis reveals a clear seasonal pattern in NH3 emissions: highest and lowest emissions are calculated for summer and winter, accounting for 42% and 14% of the total emissions, respectively. Peak emissions are calculated for July (1.7 TgNH3·yr-1) and lowest emissions for January (0.5 TgNH3·yr-1). The emissions are correlated with temperature, planting time and cultivation practices.
Kuo, Yi-Ming; Liu, Wen-Wen
The Han River basin is one of the most important industrial and grain production bases in the central China. A lot of factories and towns have been established along the river where large farmlands are located nearby. In the last few decades the water quality of the Han River, specifically in middle and lower reaches, has gradually declined. The agricultural nonpoint pollution and municipal and industrial point pollution significantly degrade the water quality of the Han River. Factor analysis can be applied to reduce the dimensionality of a data set consisting of a large number of inter-related variables. Cluster analysis can classify the samples according to their similar characters. In this study, factor analysis is used to identify major pollution indicators, and cluster analysis is employed to classify the samples based on the sample locations and hydrochemical variables. Water samples were collected from 12 sample sites collected from Xiangyang City (middle Han River) to Wuhan City (lower Han River). Correlations among 25 hydrochemical variables are statistically examined. The important pollutants are determined by factor analysis. A three-factor model is determined and explains over 85% of the total river water quality variation. Factor 1, including SS, Chl-a, TN and TP, can be considered as the nonpoint source pollution. Factor 2, including Cl-, Br-, SO42-, Ca2+, Mg2+, K+, Fe2+ and PO43-, can be treated as the industrial pollutant pollution. Factor 3, including F- and NO3-, reflects the influence of the groundwater or self-purification capability of the river water. The various land uses along the Han River correlate well with the pollution types. In addition, the result showed that the water quality of Han River deteriorated gradually from middle to lower Han River. Some tributaries have been seriously polluted and significantly influence the mainstream water quality of the Han River. Finally, the result showed that the nonpoint pollution and the point
Chen, Haiyang; Teng, Yanguo; Wang, Jinsheng
A framework for characteristics identification and source apportionment of water pollution in the Jinjiang River of China was proposed in this study for evaluation. A total of 114 water samples which were generated between May 2009 and September 2010 at 13 sites were collected and analysed. First, support vector machine (SVM) and water quality pollutant index (WQPI) were used for water quality comprehensive evaluation and identifying characteristic contaminants. Later, factor analysis with nonnegative constraints (FA-NNC) was employed for source apportionment. Finally, multi-linear regression of the absolute principal component score (APCS/MLR) was applied to further estimate source contributions for each characteristic contaminant. The results indicated that the water quality of the Jinjiang River was mainly at the third level (65.79%) based on national surface water quality permissible standards in China. Ammonia nitrogen, total phosphorus, mercury, iron and manganese were identified as characteristic contaminants. Source apportionment results showed that industrial activities (63.16%), agricultural non-point source (16.50%) and domestic sewage (12.85%) were the main anthropogenic pollution sources which were influencing the water quality of Jinjiang River. This proposed method provided a helpful framework for conducting water pollution management in aquatic environment. PMID:22592480
Huang, Fang; Wang, Ping; Qin, Yujun; Li, Yanqing
Because vegetation affect several processes including water balance, absorption and reemission of solar radiation, latent and sensible heat fluxes, and carbon cycle, the variations in the composition and distribution of vegetation represents one of the most main source of systematic change on local, regional, or global scale. To monitor and better assess natural or man-made change in vegetation of the earth is desirable for modeling and predicting interactions between land surface and atmosphere. The temporal evolution of decadal NDVI composition is regarded as an effective time window able to show the natural seasonal variations. This paper investigates vegetation change between 1998 and 2006 in the west Liao River watershed, North China, which is the east fringe of agro-pasture transitional zone in northern China and highly sensitive to global change. Time series of SPOT-VEGETATION Normalized Difference Vegetation Index (NDVI) data are used to detect the vegetation cover change during last 9 years. Results show that the yearly maximum value composite mean NDVI over the study area increased slightly from 0.277 in 1998 to 0.287 in 2006, which indicated the increasing trend of vegetation activity. The annual average NDVI value in whole area was steady. Very slight improved and slight improved area reached 113442.32 km2 and 27987.34 km2, taking up 67.81% and 16.73% of the whole study area respectively. The degraded regions occupied about 15.16%. During 1998-2006, the landscape evolution in the western Liaohe River Basin was characterized by two opposite processes, namely vegetation restoration (returning cropland for farming to grassland and close grazing) and desertification (especially land salinization). The increasing amplitude is larger than the decreasing amplitude on the whole. There was obvious decrease of monthly MNDVI in spring months, while increasing tendency of monthly MNDVI in summer and autumn was found. Results will help to provide valuable
Zhuang, B. L.; Wang, T. J.; Liu, J.; Ma, Y.; Yin, C. Q.; Li, S.; Xie, M.; Han, Y.; Zhu, J. L.; Yang, X. Q.; Fu, C. B.
Absorbing aerosols can significantly modulate short-wave solar radiation in the atmosphere, affecting regional and global climate. The aerosol absorption coefficient (AAC) is an indicator that assesses the impact of absorbing aerosols on radiative forcing. In this study, the near-surface AAC and absorption Ångström exponent (AAE) in the urban area of Nanjing, China, are characterized on the basis of measurements in 2012 and 2013 using the seven-channel Aethalometer (model AE-31, Magee Scientific, USA). The AAC is estimated with direct and indirect corrections, which result in consistent temporal variations and magnitudes of AAC at 532 nm. The mean AAC at 532 nm is about 43.23 ± 28.13 M m-1 in the urban area of Nanjing, which is much lower than that in Pearl River Delta and the same as in rural areas (Lin'an) in Yangtze River Delta. The AAC in the urban area of Nanjing shows strong seasonality (diurnal variations); it is high in cold seasons (at rush hour) and low in summer (in the afternoon). It also shows synoptic and quasi-2-week cycles in response to weather systems. Its frequency distribution follows a typical log-normal pattern. The 532 nm AAC ranging from 15 to 65 M m-1 dominates, accounting for more than 72 % of the total data samples in the entire study period. Frequent high pollution episodes, such as those observed in June 2012 and in winter 2013, greatly enhanced AAC and altered its temporal variations and frequency distributions. These episodes are mostly due to local emissions and regional pollution. Air masses flowing from northern China to Nanjing can sometimes be highly polluted and lead to high AAC at the site. AAE at 660/470 nm from the Schmid correction (Schmid et al., 2006) is about 1.56, which might be more reasonable than from the Weingartner correction (Weingartner et al., 2003). Low AAEs mainly occur in summer, likely due to high relative humidity (RH) in the season. AAC increases with increasing AAE at a fixed aerosol loading. The RH