Yangtze River Water Research Articles

Effect of coagulation pretreatment on the performance of gravity-driven membrane filtration with Yangtze River water

Gravity-driven membrane (GDM) filtration is promising for decentralized drinking water treatments. To improve the permeability and permeate quality of GDM process, three GDM systems (in-line coagulation system, pre-coagulation system, and system without coagulation as control) were operated in parallel at 65 mbar for 63 days to evaluate the effects of coagulation on flux development, permeate quality, composition and structure of the biofouling layer. The optimal dose of coagulant (polyaluminium chloride) was determined as 4 mg/L. The stable flux increased by 140% and 210% in the in-line coagulation and pre-coagulation systems compared to that of the control system, respectively. Dissolved organic compounds were removed by 31.9% and 29.4% in the in-line coagulation and pre-coagulation systems, while the control system showed a poor removal efficiency (5%). The effective removal of organics from raw water by coagulation resulted in less substrates available in the biofouling layers, thus affecting the production of extracellular polymeric substances (EPS) by limiting the biological processes. The EPS content in the biofouling layer of pre-coagulation system was the lowest, consistent with the highest flux. And such nutrient-poor biofouling layers modified the microbial community, changing the dominant bacteria from Firmicutes to Actinobacteria, thereby affecting the flux. Loose and heterogeneous biofouling layers with numerous holes and cracks were observed under coagulation conditions, which was conducive to the passage of water. All systems exhibited excellent ammonia removal efficiency (96%), but coagulation extended the start-up time for nitrification from 3 days to 5 days. Overall, these results demonstrate that coagulation can improve the GDM filtration performance, and the pre-coagulation system is globally optimal.

Numerical Study on the Expansion and Variation of Changjiang Diluted Water in Summer and Autumn

In view of the expansion and directional change mechanisms of Yangtze River water diluted with sea water in the shelf region (also known as Changjiang diluted water [CDW]) during summer and autumn, a three-dimensional hydrodynamic model of the Yangtze River Estuary (YRE) and its adjacent waters was established based on the Finite Volume Community Ocean Model (FVCOM). Compared with the measured data, the model accurately simulates the hydrodynamic characteristics of the YRE. On that basis, the influence of the expansion patterns of the CDW in both summer and autumn was studied. It was found that, in 2019, the CDW expanded to the northeast in the summer and to the southeast in the autumn, and that the route of the CDW is mainly controlled by the wind, not the runoff. Current seasonal winds also change the transportation route of the CDW by affecting its hydrodynamic field. Typhoons are frequent in both summer and autumn, causing abnormalities in both the transportation route and expansion of the CDW. During a typhoon, a large amount of the CDW is transported in a continuous and abnormal manner, accelerating the path turning of the CDW. This paper enhances the existing theoretical research of the CDW and provides a reference with respect to the expansion of diluted water all over the world.

Occurrence of N-nitrosamines and their precursors in the middle and lower reaches of Yangtze River water

The presence of some types of N-nitrosamines in water bodies is of great concern worldwide due to their carcinogenic risks and harmful mutagenic effects on human health. In the present study, eight N-nitrosamines and their formation potentials (FPs) were primarily investigated in Yangtze River surface water to evaluate their spatial distribution, mass loads, and ecological risks. The results showed that of the eight N-nitrosamines investigated, NDMA (<1.5–17 ng/L), NDEA (<1.4–9.5 ng/L), NDPA (1.0 ng/L), NMOR (<1.0–1.3 ng/L), NPIP (<2.1–3.7 ng/L), and NDBA (<3.6–30 ng/L) were detected. The FPs of NDMA (<27–130 ng/L), NDEA (<0.9–2.3 ng/L), NDPA (<1.2–1.9 ng/L), NPYR (<1.4–2.9 ng/L), NMOR (<1.0 ng/L), and NDBA (<1.1–14 ng/L) were significantly identified. NDBA was predominantly observed in surface water, while NDMA was noticeably detected in chloraminated water samples. It was estimated that approximately 5.4 t/y of N-nitrosamines were carried by the Yangtze River to the East China Sea, whereas the input flux of N-nitrosamine precursors was estimated to be approximately 69.5 t/y. Spatial variations were observed due to the input of N-nitrosamines from the upstream dams and lakes. The origin of N-nitrosamine precursors was not associated with the presence of sediment in river water. NDEA could be introduced into river water by the discharge of wastewater. NDBA and its precursors could originate from industrial and aquaculture activities. NDMA and its precursors could result from both of the aforementioned sources. Moreover, the wastewater discharge from small cities, pH value, wastewater treatment ratio, and dilution could be the key factors that influence the occurrence of N-nitrosamines along the Yangtze River. More attention should be paid to the cancer risks posed by N-nitrosamines. The ecological risks posed by N-nitrosamines in the Yangtze River can be ignored.

Thiol-grafted magnetic polymer for preconcentration of Cd, Hg, Pb from environmental water followed by inductively coupled plasma mass spectrometry detection

A novel thiol-grafted magnetic polymer (MPPs-SH) was synthesized by “click reaction” between 1,2-ethanedithiol and Fe3O4@SiO2@poly (ethylene glycol dimethacrylate -co- glycidyl methacrylate). The resultant MPPs-SH had high S content (5.4 wt%) and exhibited large specific surface area (156.8 m2 g−1) as well as high adsorption capacity of 254, 64.2, 56.6 mg g−1 for mercury, cadmium and lead ions, respectively. With the prepared MPPs-SH as sorbent, a method of magnetic solid phase extraction combined with inductively coupled plasma mass spectrometry was developed for the quantification of trace mercury, cadmium and lead in environmental water samples. The extraction conditions including sample pH, sample volume, sorbent amount, adsorption/desorption time and elution volume were optimized. Under the optimal conditions, three heavy metal ions were extracted from 150 mL aqueous solution in 10 min and eluted by 0.2 mol L−1 HNO3 containing 2% thiourea in 5 min. The method presented low limits of detection (0.21, 0.82 and 2.9 ng L−1) for target ions. The accuracy of the method was validated by using Certified Reference Materials of Environmental Water including GSB 07–1185–2000 (201435), GSB 07–1183–2000 (201239) and GSB 07–3173–2014 (202046). The application potential was further validated by the determination of trace mercury, cadmium and lead in Yangtze river and East lake water samples. The content of target heavy metal ions in tested water sample was found to be in the range of 6.40–195 ng L−1, and the recoveries of 86.4–109% were obtained at three spiking concentration levels for mercury, cadmium and lead ions.

Colorimetric detection of Cr6+ ions based on surface plasma resonance using the catalytic etching of gold nano-double cone @ silver nanorods

Hexavalent chromium ion (Cr6+) is highly toxic to human health and environment. Herein, high-performance detection of Cr6+ is of great import. In this study, a rapid and sensitive multicolor colorimetric method for detection of Cr6+ in aqueous solution was established on the basis of Cr6+ etching of gold nano-double cone@silver nanorods (Au NDC@Ag NRs). Au NDC@Ag NRs was synthesized by a modified seed-mediated growth method. The catalytic etching induced by Cr6+ changed the morphology of Au NDC@Ag NRs, leading to the attenuation of surface plasma resonance (SPR) and the redshift of absorption spectra. Meanwhile, Au NDC@Ag NRs exhibits obvious color changes from orange to pink, to purple, and finally becomes colorless with the increasing concentrations of Cr6+. With such a design, naked-eye detection of Cr6+ was realized with high sensitivity. The proposed multicolor sensing method showed a good linearity between the redshift change of absorption peak (△λ) and the concentrations of Cr6+ in the range from 2.5 to 40 μM. The limit of detection (LOD) was calculated as 1.69 μM in aqueous solution. In addition, successful detection of Cr6+ in tap water and Yangtze River water, indicating the real applications of Au NDC@Ag NRs probe in monitoring Cr6+ in environment.

Ground Deformation of Wuhan, China, Revealed by Multi-Temporal InSAR Analysis

Wuhan, the largest city in central China, has experienced rapid urban development leading to land subsidence as well as environmental concerns in recent years. Although a few studies have analyzed the land subsidence of Wuhan based on ALOS-1, Envisat, and Sentinel-1 datasets, the research on long-term land subsidence is still lacking. In this study, we employed multi-temporal InSAR to investigate and reveal the spatiotemporal evolution of land subsidence over Wuhan with ALOS-1, Envisat, and Sentinel-1 images from 2007–2010, 2008–2010, 2015–2019, respectively. The results detected by InSAR were cross-validated by two independent SAR datasets, and leveling observations were applied to the calibration of InSAR-derived measurements. The correlation coefficient between the leveling and InSAR has reached 0.89. The study detected six main land subsidence zones during the monitoring period, with the maximum land subsidence velocity of −46 mm/a during the 2015–2019 analysis. Both the magnitude and the extent of the land subsidence have reduced since 2017. The causes of land subsidence are discussed in terms of urban construction, Yangtze river water level changes, and subsurface water level changes. Our results provide insight for understanding the causes of land subsidence in Wuhan and serve as reference for city management for reducing the land subsidence in Wuhan and mitigating the potential hazards.

Stable isotope signatures of river and lake water from Poyang Lake, China: Implications for river–lake interactions

Interactions between the Yangtze River and Poyang Lake are undergoing rapid changes due to intensive human activities and ongoing climate change. This study investigates the spatiotemporal variations of isotopic compositions (δ2H and δ18O) in river and lake water to explore the river–lake interactions in combination with water level and discharge in Poyang Lake watershed. The results showed that river and lake water isotopes (δ2H and δ18O) exhibited highly temporal heterogeneity across seasons but their spatial differences were not remarkable, which is closely related with water sources from local precipitation and groundwater, and lake hydrology. The homogeneous patterns of lake water δ2H and δ18O indicated that Poyang Lake is a well-mixed lake in spatial scales. By contrast, the river (10.7‰) and lake (10.8‰) water d-excess and lc-excess (−0.6‰) were close to precipitation d-excess and lc-excess suggesting that precipitation is the main source for the lake and river. The slope and intercept of the river water line were slightly lower than those of the local meteoric water line and lake water line, which could be attributed to a greater evaporative enrichment in river water impacted by water flow regulation in the watershed. Interactions between Poyang Lake and Yangtze River vary seasonally, as evidently shown by the variations of water discharge and isotope compositions in river and lake water. The δ2H and δ18O of the Yangtze River water become more positive in the downstream zone than those in the upstream zone, indicating that the water from Poyang Lake has a great impact on downstream river water. This result can also be demonstrated by the efflux rate from the Poyang Lake to the Yangtze River, ranging from 17.9% to 67.9% across seasons except for the outlier rate in October resulted from the backflow of water from Yangtze River to the Poyang Lake. The complex lake–river interactions between Poyang Lake and Yangtze River mainly resulted from the regulation of Three Gorges Dam and water discharge from Poyang Lake watershed. These findings of the complex lake–river interactions will help to improve understanding of the hydrological processes and transport of pollutants and solutes around the confluence zone of the Yangtze River and Poyang Lake.

Swelling-shrinking modified hyperstatic hydrophilic perovskite polymer fluorescent beads for Fe(III) detection

Perovskite materials have shown great potential in various fields, such as photovoltaic devices, biomedical applications, and fluorescent probes. However, their hypersensitivity has significantly limited their practical application. In this paper, a modified swelling-shrinking strategy was adopted to encapsulate CsPbBr3 perovskite quantum dots into poly(styrene/acrylamide) nanospheres, in order to create novel hyperstatic and hydrophilic perovskite polymer fluorescent beads. The results show that the fluorescence characteristics did not noticeably change when the polymer materials were dispersed in an aqueous solution over 12 months. Under harsher conditions (acid, alkali, PBS, DMEM, temperature), the novel perovskite polymers showed unprecedented fluorescence stability, which was then applied to the selective sensing of Fe(III) in real samples. The results show that a good linear relationship between 5 and 150 μM was obtained under optimal conditions, and the limit of detection was approximately 2.2 μM. Furthermore, the Fe(III)-sensing applications in Yangtze River water, human serum and tea water has been proven with satisfying results.

Rational design and synthesis of magnetic covalent organic frameworks for controlling the selectivity and enhancing the extraction efficiency of polycyclic aromatic hydrocarbons.

A series of three-dimensional magnetic covalent organic frameworks were designed and synthesized via monomer selection, coating thickness optimization, and composite strategy transformation. Their structure properties including morphology, functional group, surface area, and pore size were characterized. The relationship between the structural properties and analytical performance was systematically investigated by density functional theory calculation and batch extraction experiments for polycyclic aromatic hydrocarbons. It is proven that the extractant modified by monomer 1,4-phthalaldehyde provides a hizgh affinity for high molecule weight polycyclic aromatic hydrocarbons and the right balance between extraction and elution efficiency. The relationship between coating thickness and mass transfer rate of polycyclic aromatic hydrocarbons was studied by accurate tuning of coating layers via layer-by-layer method. A mathematical model was derived and employed to determine that two coating layers were sufficient to provide the highest extraction efficiency with the shortest equilibrium time. The extractants synthesized by two different composite strategies (layer-by-layer and one-step) show opposite selectivity for polycyclic aromatic hydrocarbons. After optimization of theextraction conditions, dispersed solid-phase extraction coupled with gas chromatography-mass spectroscopy method was developed providing a wide linear range (5-500ngL-1), good linearity (R2 > 0.9923), high precision in intra-day (RSD% < 8.2%) and inter-day (RSD% < 12.3%) detection, and low detection limits (1.5-15.1ngL-1). The method was applied to thesimultaneous determination of 16 polycyclic aromatic hydrocarbons with acceptable recoveries, which were 87-109% for groundwater, 83-116% for East Lake water, and 82-116% for Yangtze River water samples.

Analysis of chemo-mechanical behavior of silty soil under long-term immersion in saline reservoir water

During Yangtze River reservoir impoundment, the widely distributed natural soil on the bank landslide experiences long-term water immersion. The later has a significant effect on soil deterioration, which may also aggravate landslide deformation and even cause landslide triggering. However, scarce attention has been paid to investigate the performance of bank soil immersed in reservoir water for a long period and its possible contribution to landslide deformation. This paper investigates the chemo-mechanical behavior of silty soil in the Three Gorges Reservoir area subjected to long-term Yangtze River water immersion. Chemical and mineralogical analyses, in addition to oedometer and triaxial shear tests, were carried out before and after immersion to investigate the effect of water immersion on the tested soil properties. The results showed considerable change in the soil chemo-mechanical properties induced by water immersion. The changes comprised a slow dissolution of carbonates over time, which became notable at 7 days of immersion, an increase in the silt percentage on the expense of clay, which was observed during the first stage of immersion. The effect of immersion time on the progressive change in the soil properties was dominated at 7 days, but it eventually reached equilibrium at approximately 20 days. The results indicate that soil volume change and deterioration of strength are strongly correlated to the dissolution of carbonates and changes in the soil particle size distribution.

UV/Chlorination of sulfamethazine (SMZ) and other prescription drugs: kinetics, transformation products and insights into the combined toxicological assessment

ABSTRACT The UV/chlorination of three prescription drugs, sulfamethazine (SMZ), gemfibrozil (GEM) and antipyrine (ANT) were studied by the investigation of kinetics, transformation products and combined toxicological assessment. The degradation followed pseudo-first-order kinetics, with half-lives significantly affected by chlorine dosage, without being greatly influenced by pH value and bromide concentration. Based on the Frontier Orbital Theory, the structures of products by hydroxylation or chlorine substitution were proposed and the transformation pathways were introduced, with two, two and one never-before-reported products identified for SMZ, GEM and ANT, respectively. Compared to the results of the experiments with artificial water sample, the degradation kinetics of the three prescription drugs was observed with a prolonged half-lives in both Yangtze River and Taihu Lake water, suggesting that aromatic containing transformation products (TPs) may also exist in UV/chlorine treated natural waters. The results of combined toxicity on E. coli showed that the antagonism effect predominated in most binary and ternary combinations. However, the synergistic toxicity of combinations at low concentrations of prescription drugs subjected to UV/chlorine should be cautioned, which was more close to the natural concentration of prescription drugs in waters.

Solar photocatalytic degradation of thidiazuron in Yangtze River water matrix by Ag/AgCl-AC at circumneutral condition.

It is well-known that the degradation of pollutants in real water environment is not only challenging but also has practical value. This paper focuses on the photocatalytic degradation of thidiazuron (TDZ), a popular defoliant, using Ag/AgCl-AC (Ag@AC 2:1); AC stands for activated carbon) in a matrix of Yangtze River water under sunlight irradiation. The prepared composite catalyst exhibits excellent performance in TDZ degradation under near neutral condition, the degradation rate reaches 94% in 200min under solar irradiation. The common inorganic anions (SO42-, Cl-, and HCO3-) and cations (Ca2+, Cu2+, and Mg2+) show inhibitory effect of different degrees on TDZ degradation. Humic substances such as humic acid and fulvic acid also have an effect on the photocatalytic degradation of TDZ. With the increase of humic acid concentration, there is enhancement of inhibitory effect. As for fulvic acid, its effect is complex due to competitive adsorption and photoinduction action. The degradation products as identified by UHPLC-MS are mainly CO2, SO2, and H2O, indicating that the degradation was thorough. The reusability test of four runs reveals that the performance of the photocatalytic system is stable. The results demonstrate that sunlight can be well utilized for the photocatalytic degradation of TDZ. The study offers a cheap and effective approach for the photocatalytic degradation of organic pollutants in circumneutral water bodies.

Impacts of cascade reservoirs on Yangtze River water temperature: Assessment and ecological implications

The natural hydrological regime of the Yangtze River has been influenced by dam construction over past decades. More reservoirs are being built and have been planned in the upper reach of the Yangtze River (URYR). To investigate the effects of reservoirs in the URYR and the Three Gorges Reservoir (TGR) on the water temperature regime, a reservoir water heat model combined with the Soil and Water Assessment Tool is used to simulate the water temperature change under different scenarios. The results show that the water temperature regime has been dramatically altered by reservoir operation, especially in spring and autumn. Reservoir operations impose a noticeable hysteresis effect on water temperature rising and falling processes, thereby resulting in a delay of the suitable temperature date for the Chinese Sturgeon (Acipenser sinensis) and four famous major carps. When more reservoirs are put into use, the delays in the target spawning times of these fishes will be further exacerbated. Modifying operation modes of these reservoirs and depth of water release is necessary during fish spawning seasons, which could facilitate a better balance between ecological and socioeconomic demands. We hope the results of this study will be useful to the river ecosystem health and stability.

Seasonal variability of stable isotopes in the Changjiang (Yangtze) river water and its implications for natural climate and anthropogenic impacts

BackgroundSeasonal variations of stable hydrogen and oxygen isotopes in river water can be used to indicate hydrological processes and the water cycle in the river basin. This study presents a high-resolution time series of stable oxygen isotopic record (δ18O) in the lower Changjiang (Yangtze) River mainstream and aims to investigate the regional water cycle concerning natural climate changes and anthropogenic activities.ResultsThe river water δ18O shows apparent seasonal variations, which is overall higher during the dry season and lower during the flood season. This basin-scale seasonal variation of δ18O in precipitation over the Changjiang catchment is calculated based on the long-term meteorological and hydrological data. The seasonal variation of δ18O in the lower Changjiang river water is largely constrained by monsoon-induced precipitation, but is more directly controlled by the mixing of waters from the upper reaches and the tributary lakes in the middle valley.ConclusionsThe relative contributions of waters from the upstream and tributary lakes to the lower Changjiang mainstream have been considerably altered by the construction of Three Gorges Dam via the regulation of river discharges. A comparison of river water isotopic records with water discharges from the lakes suggests that it takes about 2 weeks (~ 17 days) for the Changjiang river water to circumvent the mid-lower reaches of the catchment before traveling to the sea. This study suggests that the stable hydrogen and oxygen isotopes can be harnessed as sensitive indicators for water cycling within a large catchment that is driven primarily by natural forcing though subject to substantial human impacts.

A zeolitic imidazolate framework/carbon nanofiber nanocomposite based electrochemical sensor for simultaneous detection of co-existing dihydroxybenzene isomers

Zeolitic imidazolate framework-8 (ZIF-8) was prepared by an easy static method and combined with conductive carbon nanofiber (CNF) to fabricate a novel electrochemical sensor for simultaneous detection of co-existing dihydroxybenzene isomers. The characterization of ZIF-8/CNF nanocomposite was performed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Under the optimized conditions, this proposed sensor showed excellent electrocatalytic activity with detection limits of 0.06 μM, 0.08 μM and 0.32 μM (S/N = 3) for hydroquinone (HQ), catechol (CC) and resorcinol (RS) respectively and with a same linear concentration range of 2−400 μM. In addition, it possessed great reproducibility, stability and selectivity and obtained satisfactory recovery results in real analysis of lake water and Yangtze River water.

Efficient BiVO4 photoanode decorated with Ti3C2TX MXene for enhanced photoelectrochemical sensing of Hg(II) ion

A highly sensitive photoelectrochemical (PEC) sensing platform was constructed for Hg2+ determination based on the Schottky heterojunction between an emerging 2D material Ti3C2TX MXene and a promising semiconductor material BiVO4. Through simply spin-coating the single-layer Ti3C2TX onto the surface of BiVO4 film, the modified electrode exhibited significantly enhanced PEC activity. However, the boost in photocurrent could be noticeably suppressed due to the consumption of hole-scavenging agents (reduced glutathione) by the added Hg2+. Owing to the selective decrease in the photocurrent with the addition of Hg2+, the PEC sensor based on BiVO4/Ti3C2TX displayed a wide linear range from 1 pM to 2 nM with the limit of detection down to 1 pM. Moreover, the PEC sensor also exhibited satisfactory accuracy and repeatability in practical sample water, the Yangtze River water, demonstrating the great potential for monitoring heavy metal ions in natural water resources.

Online simultaneous speciation of ultra-trace inorganic antimony and tellurium in environmental water by polymer monolithic capillary microextraction combined with inductively coupled plasma mass spectrometry

Poly(glycidyl methacrylate-ethylene dimethacrylate) monolithic capillary was functionalized with cystamine, and the resultant mercapto functionalized polymer monolithic capillary was investigated for the separation of Sb(III) and Sb(V) as well as Te (IV) and Te(VI). It was found that Sb(III) and Te(IV) were selectively retained on the prepared monolithic capillary over a wide pH range (1–8), while Sb(V) and Te(VI) were not be adsorbed in the pH range of 3–8. Based on it, a method of capillary microextraction online hyphenated with ICP-MS was proposed for simultaneous speciation of trace inorganic Sb and Te. Sb(V) and Te(VI) were pre-reduced simultaneously into Sb(III) and Te(IV) and subjected to the proposed method to get the information of total Sb and Te; the content of Sb(V) and Te(VI) was calculated by subtracting Sb(III) and Te(IV) from total Sb and Te. Under the optimized conditions, the limits of detection for Sb(III) and Te(IV) were 3.9 and 5.9 ng L−1 with the relative standard deviations of 5.2 and 4.1% (c = 0.1 μg L−1, n = 7), respectively. The accuracy of the method was verified by Certified Reference Materials of Environmental Water (GSB07–1376-2001, GBW(E)080548). In real water samples analysis, sub-μg L−1 of Sb(V)/(III) was found in the Yangtze River and East Lake water, and the recoveries for the spiked real water samples for Sb(V)/(III) and Te(IV)/(VI) were 87.0–113% and 83.5–107%, respectively. The proposed approach was rapid, sensitive and exhibited great application potential in the simultaneous speciation of inorganic Sb and Te in environmental waters.

Variations of Stable Oxygen and Deuterium Isotopes in River and Lake Waters During Flooding Season Along the Middle and Lower Reaches of the Yangtze River Regions

Stable isotope tracers have been widely applied to water sources and evolution, transforming relations, and pollution sources of various water bodies. This study analyzed the spatial variations of δ2H and δ18O in river and lake waters during flooding season, and revealed the factors underlying their variations along the middle and lower reaches of the Yangtze River based on a field sampling campaign in July 2018. Our results showed that δ2H and δ18O in the Yangtze River water were enriched from the Three Gorges reservoir region to the lower reaches of the Yangtze River, which was closely linked to isotopic variations in precipitation. There was no significant difference in δ2H and δ18O values in the mainstream river waters between the Three Gorges Reservoir Region and Yichang-Chenglingji. However, d-excess values in river water displayed a small variation range. In contrast, δ2H and δ18O values in the lake group from Dongting to Jianghan and Huayang to Poyang Lake were lower than in the lake group from Taihu to the Yangtze Delta. Negative d-excess values were observed in lake water from Taihu to the Yangtze Delta, suggesting the combined influence of enriched isotopic compositions in precipitation and strong evaporative enrichment. Of the lakes, the highest isotopic values were found in Dianshan Lake and Datong Lake, whereas the lowest isotopic values were recorded in Dongting Lake and Poyang Lake because of their direct connection with the Yangtze River. The water regimes of Dongting Lake and Poyang Lake were influenced by the Yangtze River, especially when a high water level of the Yangtze River occurred, and thus altered the isotopic compositions of Dongting Lake and Poyang Lake water. Hence, these findings will provide scientific data revealing the precipitation-river-lake interactions and investigating the rational utilization and management of water resources in the middle and lower reaches of the Yangtze River regions.

Antibiotics in wastewater from multiple sources and surface water of the Yangtze River in Chongqing in China.

Antibiotic contamination attracts growing concerns because of their deleterious effects on the ecosystem and human health. In this study, 43 antibiotics in wastewater from a variety of sources and water of the Yangtze River in Chongqing City in western China were measured. Thirty compounds were detected, and their concentrations were highest in leachates from the municipal solid waste treatment facilities (landfills and incineration plants) with total concentrations of 3584-57,106ng/L. The total concentrations in influents of municipal and industrial wastewater treatment plants (WWTPs) were comparable (401-7994ng/L versus 640-8945ng/L). The concentrations in raw sewage from swine farms (with a total of 10,219-39,195ng/L) and poultry farms (1419-36,027ng/L) were noticeably higher than those from other farms (54.0-5516ng/L). Fluoroquinolones were the dominant antibiotics contributing over 50% in all the sources, and sulfonamides and imidazole fungicides contributed 3.2-34%, whereas tetracyclines and macrolides had minor contributions. The overall antibiotic removal rates were highest in solid waste treatment facilities (88% on average), comparable between municipal and industrial WWTPs (61%), and lowest in animal farms (39%). The mass loads to the investigated municipal WWTPs via influent wastewater ranged from 7.80 to 1531kg/year (53.2-2482μg/day per capital). The influent mass loads to the industrial WWTPs and farms were 3.7-50kg/year and 0.9-5437g/year, respectively. We estimated that the mass inventories of antibiotics from these sources to the environment via effluent discharges were approximately 2044kg for municipal WWTPs, 61kg for industrial WWTPs, and 34kg for animal farms in the whole city. Antibiotic concentrations in the Yangtze River water were substantially low (< 492ng/L, with a mean of 57.8ng/L) suggesting dissipation during the movement.

Multiscale Study of Physical and Mechanical Properties of Sandstone in Three Gorges Reservoir Region Subjected to Cyclic Wetting–Drying of Yangtze River Water

Natural rock often suffers from cyclic wetting–drying involving different water types, and the resulting deterioration may differ from laboratory tests using distilled water or salt solutions. An inappropriate estimation of this deterioration effect may lead to fatal geological hazards and engineering failures. A multiscale study is conducted to investigate the physical and mechanical features of sandstone in Three Gorges Reservoir region (TGR sandstone) subjected to cyclic wetting–drying of Yangtze River water. During this study, three types of water, i.e., Yangtze River water, ionized water having similar ion compositions as the Yangtze River water, and distilled water, are used for comparison. The results show that the multiscale physical properties including mineral compositions (especially calcite and albite), micro-pore parameters, computed tomography values, and macro-mechanical parameters (i.e., Young’s modulus, uniaxial compression strength and tensile strength) are remarkably altered during the cyclic wetting–drying process. Significant correlations are found between these numerous multiscale properties. The results indicate that changes of mineral compositions and microstructure are the primary reasons for the deterioration of sandstone strength. The deterioration effect of distilled water on TGR sandstone is the least, while the effect of ionized water is the greatest, and that of river water being intermediate. These differences are ascribed to different chemical interactions, together with possible microorganism effects for river water, as microorganisms in river water potentially weaken the deterioration of cyclic wetting–drying of river water. In situ water is recommended for studying how rock properties are affected by water–rock interactions in real settings.