[Hydrochemical Evolution in the Yarlung Zangbo River Basin].

In order to explore the hydro-chemical evolution law of the Yarlung Zangbo River Basin from 1973 to 2020, the hydro-chemical characteristics and major ion sources were studied using a Piper diagram, Gibbs diagram, ion ratio, and correlation analysis, and the irrigation applicability of the Yarlung Zangbo River was evaluated using the sodium adsorption ratio (SAR), sodium percentage (Na+%), and permeability index (PI). The results showed that the mean value of TDS was (208.30±58.26) mg·L-1, which increased with time. Ca2+ was the dominant cation, accounting for (65.49±7.67)% of the total cations. HCO-3 and SO2-4 were the dominant anions, accounting for (68.56±9.84)% and (26.85±9.82)% of the main anions, respectively. The annual growth rates of Ca2+, HCO-3, and SO2-4 were respectively 2.07, 3.19, and 4.70 mg·(L·10 a)-1. The hydro-chemical type of the Yarlung Zangbo River was HCO3-Ca type, and the main ionic chemistry was controlled by the chemical weathering of carbonate rocks. The weathering of carbonate rocks during the period of 1973 to 1990 was mainly controlled by carbonation, whereas from 2001 to 2020 it was mainly controlled by both carbonation and sulfuric acid. The main ion concentrations in the mainstream of Yarlung Zangbo River were within the range of drinking water standards, with SAR between 0.11-0.93, Na+% between 8.00-36.73, and PI values between 0.39-0.87, demonstrating that the waters were suitable for drinking and irrigation. The results were of great significance to the protection and sustainable development of water resources in the Yarlung Zangbo River Basin.

[Hematological Characteristics of Different Genotypes of Thalassemia among Reproductive Population in Chongqing].

OBJECTIVE: To investigate the hematological characteristics and genotype distribution of thalassemia among people at reproductive age in Chongqing. METHODS: Hematology analysis and capillary electrophoresis were performed in 29 145 participants at reproductive age. The patients with positive results were confirmed by thalassemia genotyping. Genotype distribution and characteristics of mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and hba2 levels in thalassemia patients were analyzed. RESULTS: --SEA/αα (45.10%), -α3.7/αα (39.31%) and -α4.2/αα (8.46%) were the most common genotypes of α-thalassemia, while CD17 (HBB: c. 52A>T) (31.67%), CD41-42 (HBB: c. 126-129 del TTCT) (26.87%) and IVS-Ⅱ-654 (HBB: c. 316-197 C>T) (24.21%) were the most common genotypes of ß-thalassemia in Chongqing. In α-thalassemia ααCS/αα showed the lowest hba2 value (2.18±0.23)%, while --SEA/αα showed the lowest MCV (71.9±8.5) fl and MCH (22.7±3.3) pg value. The patients in ßE (HBB: c. 79G>A) group showed comparatively higher values of MCV and MCH and significantly lower HbA and hba2 values than the other genotypes. There was no significant difference in HbA, hba2, MCV, MCH levels of the patients between pregnant group and non-pregnant group. CONCLUSIONS: In Chongqing, there are differences in hematological characteristics among patients with different thalassemia genotypes. There is no significant effect of pregnancy on HbA, hba2, MCV and MCH has been found.

Environmental enrichment combined with fasudil promotes motor function recovery and axonal regeneration after stroke.

Fasudil, a Rho-associated protein kinase (ROCK) inhibitor, has a protective effect on the central nervous system. In addition, environmental enrichment is a promising technique for inducing the recovery of motor impairments in ischemic stroke models. The present study aimed to explore whether environmental enrichment combined with fasudil can facilitate motor function recovery and induce cortical axonal regeneration after stroke. First, a mouse model of ischemic cerebral stroke was established by photochemical embolization of the left sensorimotor cortex. Fasudil solution (10 mg/kg per day) was injected intraperitoneally for 21 days after the photothrombotic stroke. An environmental enrichment intervention was performed on days 7-21 after the photothrombotic stroke. The results revealed that environmental enrichment combined with fasudil improved motor function, increased growth-associated protein 43 expression in the infarcted cerebral cortex, promoted axonal regeneration on the contralateral side, and downregulated ROCK, p-LIM domain kinase (LIMK)1, and p-cofilin expression. The combined intervention was superior to monotherapy. These findings suggest that environmental enrichment combined with fasudil treatment promotes motor recovery after stroke, at least partly by stimulating axonal regeneration. The underlying mechanism might involve ROCK/LIMK1/cofilin pathway regulation. This study was approved by the Institutional Animal Care and Use Committee of Fudan University, China (approval No. 20160858A232) on February 24, 2016.

Environmental enrichment combined with fasudil treatment inhibits neuronal death in the hippocampal CA1 region and ameliorates memory deficits.

Currently, no specific treatment exists to promote recovery from cognitive impairment after a stroke. Dysfunction of the actin cytoskeleton correlates well with poststroke cognitive declines, and its reorganization requires proper regulation of Rho-associated kinase (ROCK) proteins. Fasudil downregulates ROCK activation and protects neurons against cytoskeleton collapse in the acute phase after stroke. An enriched environment can reduce poststroke cognitive impairment. However, the efficacy of environmental enrichment combined with fasudil treatment remains poorly understood. A photothrombotic stroke model was established in 6-week-old male C57BL/6 mice. Twenty-four hours after modeling, these animals were intraperitoneally administered fasudil (10 mg/kg) once daily for 14 successive days and/or provided with environmental enrichment for 21 successive days. After exposure to environmental enrichment combined with fasudil treatment, the number of neurons in the hippocampal CA1 region increased significantly, the expression and proportion of p-cofilin in the hippocampus decreased, and the distribution of F-actin in the hippocampal CA1 region increased significantly. Furthermore, the performance of mouse stroke models in the tail suspension test and step-through passive avoidance test improved significantly. These findings suggest that environmental enrichment combined with fasudil treatment can ameliorate memory dysfunction through inhibition of the hippocampal ROCK/cofilin pathway, alteration of the dynamic distribution of F-actin, and inhibition of neuronal death in the hippocampal CA1 region. The efficacy of environmental enrichment combined with fasudil treatment was superior to that of fasudil treatment alone. This study was approved by the Animal Ethics Committee of Fudan University of China (approval No. 2019-Huashan Hospital JS-139) on February 20, 2019.

[Seasonal Variation of DOM Spectral Characteristics of Rivers with Different Urbanization Levels in the Three Gorges Reservoir Area].

The urbanization process of the Three Gorges Reservoir area (TGRA) shows important impacts on the formation, migration, and transportation of dissolved organic matter (DOM) in rivers. In this study, a high-urbanized river (Taohuaxi) and low-urbanized river (Pulihe) in the TGRA were selected and water samples were collected in spring (April) and summer (August) to analyze the seasonal and spatial characteristics of DOM in the rivers using UV-Vis absorption spectroscopy and three-dimensional fluorescence spectroscopy. The DOC, S275-295 (the spectral slope of the short wavelength range), SR (spectral slope ratio), BIX (recent autochthonous contribution), and Fn(280) (relative importance of protein-like substances) of the Taohuaxi and Pulihe Rivers were higher in summer (August) than in spring (April), and CDOM concentration, CDOM/DOC, SUVA254 (aromatic structure), SUVA260 (hydrophobic component), E3/E4 (proportion of fulvic acid), S350-400 (the spectral slope of the long wavelength range), and HIX (the degree of humification) were higher in spring than in summer. The overall averages of the DOC, CDOM concentration, SR, Fn (280), BIX, and FI were higher in the high-urbanized Taohuaxi River than the low-urbanized Pulihe River, whilst the CDOM/DOC, SUVA254, and SUVA260 were lower in the Taohuaxi River. With the increase of urbanization along the water flow pathways, SUVA254 and SUVA260 gradually decreased, while Fn (280) gradually increased. The humus source (FI) of the two rivers in spring and summer is mixed and includes terrigenous and biological sources (plankton and algae) but is mostly endogenous. Furthermore, DOM is characterized by a moderately recent autochthonous contribution. Our study implies a large impact of urbanization on the composition and sources of DOM.

[Absorption and Fluorescence Spectra of Dissolved Organic Matter in Rivers of the Three Gorges Reservoir Area Under the Background of Urbanization].

Studying the influences of urbanization on the composition, chemical structure, source and migration of dissolved organic matter (DOM) in rivers is of great significance for aquatic ecosystem protection and biogeochemical carbon (C) cycling. The DOM spectroscopic characteristics of the three typical rivers (Taohuaxi, Nanhe, and Puli) with different urbanization levels in the Three Gorges Reservoir area were investigated using the ultraviolet-visible (UV-Vis) absorption spectrum and three-dimensional fluorescence spectroscopy. The results demonstrated that the higher the degree of urbanization in rivers, the greater the concentrations of DOM and chromophoric dissolved organic matter (CDOM), the lower the humification degree and aromaticity of DOM, the smaller the proportion of hydrophobic components, the higher the relative level of protein-like substance concentration in DOM, and the greater the contribution of DOM from freshly autochthonous origins. The DOM of the three rivers was dominated by fulvic acids (E3/E4>3.5), and CDOM concentration was positively correlated with the concentration of DOM (P<0.01). There were significant positive correlations between the humification degree (SUVA254), aromaticity (SUVA280), and hydrophobic component (SUVA260) (P<0.01). The sources of humic substances in the DOM were mixed by terrestrial input and microbial or algae production (reflected by the fluorescence index averages of 1.7157-1.7571), and mainly from microbial sources.

[Micro-ribonucleic acids participate in electroacupuncture intervention-induced improvement of ischemic stroke].

Ischemic stroke is a major cause of permanent disability and death in adults, and electroacupuncture (EA) intervention has a positive role in improving neurological function in patients with ischemic stroke through a series of complex processes. In the present paper, we make a review about the development of researches on the involvement of micro-ribonucleic acid (miRNA) in ischemic stroke from excitatory amino acid toxicity, oxidative stress, inflammatory response, apoptosis and necrosis, and particularly sum up outcomes of researches about the roles of miRNAs in EA-induced improvement of neurological function in experimental cerebral ischemia animals. EA treatment can 1) balance levels of miRNAs (such as mir-126 and mir-328, etc.) to promote angiogenesis of ischemic cerebral cortex tissue by regulating expression of vascular endothelial growth factor family genes and proteins; 2) promote nerve regeneration by up-regulating serum miR-124 and hippocampal miR-132 expression to possibly facilitate cerebral repair and reduce cognitive dysfunction respectively via related proteins; 3) reduce cerebral edema via modulating expression of some miRNAs to control expression of aquaporin, matrix metalloproteinases, etc. and 4) suppress inflammatory response via up-regulating expression of miRNAs to inhibit expression of NF-κB, TNF-α, etc. in the local cerebral tissue. As a result, the neurological function is bettered after EA intervention.

[Water-Air Interface CO2 Exchange Flux of Typical Lakes in a Mountainous Area of the Western Chongqing and Their Influencing Factors].

To examine the mountainous lake CO2 evasion in Southwest China, partial pressures of carbon dioxide[p(CO2)] and the CO2 exchange flux[F(CO2)] via the water-air interface of nine mountainous lakes in Chongqing, China, have been studied in summer using the thin boundary layer model (TBL) and floating chambers. Key water quality parameters were concomitantly measured. The results indicate that the pCO2 in the mountainous lakes in western Chongqing ranges from 2.1 to 45.0 Pa, with a mean value of (18.1±12.1) Pa. The mean CO2 fluxes calculated by the TBL model and chamber method are (-8.0±2.9), (-3.4±3.6), and (-7.1±22.3) mmol·(m2·d)-1, respectively. The p(CO2) and F(CO2) have positive correlations with the wind speed and ORP but negative correlations with the pH. Our study indicates that mountainous lakes are atmospheric sinks of CO2 and the TBL model should be cautiously adopted.

[pCO2 in the Main Rivers of the Three Gorges Reservoir and Its Influencing Factors].

An extensive investigation on the main tributaries of the Three Gorges Reservoir (TGR) region was conducted in autumn (Oct. 2015), with focuses on riverine CO2 partial pressure (pCO2) and its associated controls. Our results indicated that pCO2 in the main rivers of the TGR region ranged from 18.75 to 296.31 Pa, with a mean value of (141.06±77.51) Pa in the autumn, which was much higher than the atmospheric CO2 concentration. Therefore, the studied rivers acted as an atmospheric CO2 source, and the mean CO2 emission rate to the atmosphere was estimated at (101.1±78.0) mmol·(m2·d)-1. The highest and lowest values were (131.9±101.8) and (70.3±54.3) mmol·(m2·d)-1, respectively. pCO2 in the main rivers of the TGR area was significantly related to DO, pH, and bicarbonate. Furthermore, the biogeochemical process of within-river respiration of organic carbon rather than photosynthesis resulted in negative relationships between pCO2 and DO or pH because of the high velocities and short residence time in these mountainous rivers and streams. Our results will help to accurately develop the carbon budget for the rivers of the Three Gorges Region.

Temperature sensitivity of biodegradable dissolved organic carbon increases with elevating humification degree in subtropical rivers.

Biodegradable dissolved organic carbon (BDOC) plays a key role in C cycle in inland waters. However, the magnitude of temperature sensitivity (Q10 value) of BDOC is still unclear, and the effect of DOC quality on Q10 value of BDOC is not well verified in these aquatic systems. Here, we used a laboratory incubation experiment to determine the Q10 value of BDOC in 57 rivers in the Three Gorges Reservoir area, China, and then tested whether C quality-temperature hypothesis could be applied to BDOC in inland waters. We observed approximately twofold variations in Q10 values of BDOC (1.42-2.67) in these rivers. Moreover, the tight positive relationship between the Q10 values of BDOC and DOC humification index indicated the applicability of C quality-temperature hypothesis in subtropical rivers. In addition, the Q10 values of BDOC exhibited a negative relationship with pH. These findings suggest that DOC quality and pH are powerful predictors of temperature sensitivity of BDOC in subtropical rivers. In conclusion, our results would help to improve the C models and predict the feedback between climate warming and C dynamics in inland waters.

[Daily Variation of CO2 Flux at Water-Air Interface and Analysis of Its Affecting Factors in a Typical River of the Three Gorges Reservoir].

Diurnal and seasonal characterization of CO2 partial pressure p(CO2) and CO2 areal flux F(CO2) at the water-air interface in an anthropogenic river in the Three Gorges Reservoir area was studied. A tributary of the Jialing River in Chongqing Municipality was chosen, and daily and seasonal samples were taken in summer and autumn, focusing on riverine p(CO2), F(CO2), and their associated controls. Henry's law combined with the thin boundary layer model was adopted to estimate the CO2 flux via the water-air interface. The results indicated that F(CO2) was not high on average, namely (87.8±27.5) mmol·(m2·d)-1 and (139.2±34.0) mmol·(m2·d)-1 in summer and autumn, respectively. The water-air interface F(CO2) showed significant hourly, daily, and seasonal variations. CO2 release peaked around 09:00 and then slightly decreased. We also found that pH, alkalinity, water, and temperature were significantly related to p(CO2) and F(CO2), whereas pH and alkalinity were the best predictors of F(CO2). This study aids understanding of the impacts of urbanization on CO2 emissions in the rivers and helps to re-evaluate local riverine CO2 budgets.

Serum Response Factor Promotes Dopaminergic Neuron Survival via Activation of Beclin 1-Dependent Autophagy.

Serum response factor (SRF), a transcription factor highly expressed in neurons, is involved in neuronal survival and the pathogenesis of some neurodegenerative disorders. The ablation of SRF renders the midbrain dopaminergic (DA) neurons vulnerable to 1-methyl 4-phenyl 1,2,3,6-tetrahydropyridine-induced neurotoxicity, however, the underlying mechanisms remain poorly understood. Here, we report decreased SRF levels in the substantia nigra (SN) of rotenone-treated rats that was associated with the loss of tyrosine hydroxylase (TH)-positive neurons. SRF expression was also reduced in rotenone-treated PC12 cells in vitro. In addition, Srf knockdown augmented rotenone-induced toxicity in PC12 cells. In contrast, overexpression of Srf attenuated the cells' sensitivity to rotenone and alleviated rotenone-induced α-synuclein accumulation. The protective effect of SRF was abolished when the expression of autophagy-related proteins Beclin 1 and Atg5 was suppressed. These results suggested that SRF may promote DA neuron survival by regulating autophagy, and thus serves as a critical molecule in PD progression.

Long-term phosphorus addition enhances the biodegradability of dissolved organic carbon in a nitrogen-limited temperate freshwater wetland.

Phosphorus (P) enrichment is expected to strongly influence dissolved organic carbon (DOC) biodegradation. However, the relationship between P availability and DOC biodegradation is largely unknown in nitrogen (N)-limited ecosystems. Here, we investigated the changes in the ratio of DOC to dissolved total nitrogen (DTN), specific UV absorbance at 254nm (SUVA254), and DOC biodegradation in surface water and soil pore water (0-15cm depth) following eight years of multi-level P addition (0, 1.2, 4.8, and 9.6gPm-2year-1) in an N-limited freshwater marsh in Northeast China. We found that P addition caused an increase in DOC biodegradation in surface water and soil pore water, irrespective of the P addition levels. Compared with the control treatment, the P addition rates of 1.2, 4.8, and 9.6gPm-2year-1 increased DOC biodegradation by 20.7%, 15.2%, and 14.5% in surface waters, and 11.3%, 9.4%, and 12.0% in soil pore waters, respectively. The DOC biodegradation was separately negatively correlated with the DOC:DTN ratio and SUVA254, indicating that the positive effect of P addition on DOC biodegradation was caused by the elevated N concentration and the reduced DOC aromaticity. Our findings suggest that P enrichment enhances the biodegradability of DOC through increased N availability and altered DOC chemical composition, which would accelerate DOC loss from the waters and alter ecosystem C balance in N-limited temperate wetlands.

Long-term Levodopa Treatment Accelerates the Circadian Rhythm Dysfunction in a 6-hydroxydopamine Rat Model of Parkinson's Disease.

BACKGROUND: Parkinson's disease (PD) patients with long-term levodopa (L-DOPA) treatment are suffering from severe circadian dysfunction. However, it is hard to distinguish that the circadian disturbance in patients is due to the disease progression itself, or is affected by L-DOPA replacement therapy. This study was to investigate the role of L-DOPA on the circadian dysfunction in a rat model of PD. METHODS: The rat model of PD was constructed by a bilateral striatal injection with 6-hydroxydopamine (6-OHDA), followed by administration of saline or 25 mg/kg L-DOPA for 21 consecutive days. Rotarod test, footprint test, and open-field test were carried out to evaluate the motor function. Striatum, suprachiasmatic nucleus (SCN), liver, and plasma were collected at 6:00, 12:00, 18:00, and 24:00. Quantitative real-time polymerase chain reaction was used to examine the expression of clock genes. Enzyme-linked immunosorbent assay was used to determine the secretion level of cortisol and melatonin. High-performance liquid chromatography was used to measure the neurotransmitters. Analysis of variance was used for data analysis. RESULTS: L-DOPA alleviated the motor deficits induced by 6-OHDA lesions in the footprint and open-field test ( P < 0.01, P < 0.001, respectively). After L-DOPA treatment, Bmal1 decreased in the SCN compared with 6-OHDA group at 12:00 ( P < 0.01) and 24:00 ( P < 0.001). In the striatum, the expression of Bmal1, Rorα was lower than that in the 6-OHDA group at 18:00 (P < 0.05) and L-DOPA seemed to delay the peak of Per2 to 24:00. In liver, L-DOPA did not affect the rhythmicity and expression of these clock genes (P > 0.05). In addition, the cortisol secretion was increased (P > 0.05), but melatonin was further inhibited after L-DOPA treatment at 6:00 (P < 0.01). CONCLUSIONS: In the circadian system of advanced PD rat models, circadian dysfunction is not only contributed by the degeneration of the disease itself but also long-term L-DOPA therapy may further aggravate it.

Effect of long-term phosphorus addition on the quantity and quality of dissolved organic carbon in a freshwater wetland of Northeast China.

Understanding how P enrichment alters the quantity and quality of dissolved organic carbon (DOC) is important, because of their role in regulating the C cycle. Here, we established a four-level P addition experiment (0, 1.2, 4.8, and 9.6gPm-2year-1) in a N-limited freshwater wetland in the Sanjiang Plain, Northeast China. The aim of this study was to examine the effects of eight years of P addition on DOC concentration, SUVA254 (Abs254/DOC concentration, indicating the aromaticity of DOC), C:C ratio (Abs400/DOC concentration, indicating the proportion of colored humic substances in DOC), and E4:E6 ratio (Abs465/Abs665, indicating the molecular size of humic substances) in surface water and soil pore water (0-15cm depth) during the growing season (June through September). Our results showed similar changing trends in concentration and optical properties of DOC following eight years of P addition in the both surface water and soil pore water across the sampling dates. Generally, P addition decreased DOC concentration, SUVA254, and C:C ratio, and increased E4:E6 ratio, irrespective of P addition levels. These altered optical properties of DOC indicated that P addition decreased the molecular weight and aromaticity of DOC, and thus increased the quality of DOC. These results suggest P enrichment substantially reduces the quantity of DOC in N-limited temperate freshwater wetlands, and imply that increased DOC quality following P addition can further provide a positive feedback to decreased DOC pool.

Molecular epidemical characteristics of Lamivudine resistance mutations of HBV in southern China.

BACKGROUND: Lamivudine (LMV), as the preferred oral drug for use in treatment of HBV, always results in development of resistance mutations after long-term treatment. In this study we investigated chronic hepatitis B (CHB) patients in southern China to determine whether different HBV genotypes affect the incidence of LMV resistance mutations. MATERIAL/METHODS: The study recruited 185 CHB patients living in southern China. Enzyme-linked immunosorbent assay was used to test for HBV serological markers, and HBV DNA was quantified by real-time PCR. Sequencing was performed to detect HBV genotypes and mutations. RESULTS: There were 49.19% (91/185) CHB patients with HBV resistant to LMV. Only 2 genotypes were found: B and C; 62.16% (115/185) of patients were infected with genotype B HBV and 37.84% (70/185) of patients were infected with genotype C HBV. The incidence rate of LMV resistance was not significantly different between genotype B and C (49.57% vs. 48.57%, P>0.05). For the mean age and sex ratio, no significant difference was found. The pattern of rtM204I alone was predominantly observed (36.26%, 33/91), followed by rtM204V+rtL180M (23.08%, 21/91). The overall incidence rate of rtM204I mutation in genotype B (45.61%, 26/57) was more frequent than that in genotype C (20.59%, 7/34) (45.61% vs. 20.59%, P<0.05), but the incidence rate of other mutation patterns was not significantly different between genotypes B and C. CONCLUSIONS: Our results emphasize that a LMV resistance test before treatment is of great importance in rational and optimal CHB therapy.

[Hydro-chemical characteristics in the Danjiangkou Reservoir (water source area of the middle route of the south to north water transfer project), China].

TDS, pH and major ions in the Danjiangkou Reservoir, the water source area of the Middle Route of the South to North Water Transfer Project of China were monitored during the period of 2004-2006 to systemically analyze hydro-chemical characteristics and water chemistry type. Analysis of variance (ANOVA) and correlation analysis were performed to explore their spatio-temporal pattern. The results show that the water is of low mineralized degree with a total dissolved solid ranging from 149.9-291.2 mg x L(-1), and soft water with a total hardness ranging from 40-50 mg x L(-1) x HCO3- accounts for 77.54%-77.87% of the total major anions with a content of 122.5-170.0 mg x L(-1), while Ca2+ accounts for 70.66%-77.93% of the total major cations with a content of 37.1-43.2 mg x L(-1), and the water is of a HCO3- -Ca type. Major ions show similar spatial variations, decreasing downstream in the Danjiang Reservoir, and reaching the lowest values in the Hanjiang Reservoir. The temporal and seasonal variations of the hydro-chemical characteristics show that the concentrations of major ions in the dry season are larger than those in the wet season. Hydro-chemical characteristics in the reservoir are mainly determined by the rock weatherization, while and anthropogenic activities in the upper-stream and the reservoir region have been influencing the NO3- concentration. Finally, conservation strategies of water resource in the reservoir and its upper stream are discussed.

[Seasonal variation in the major ion chemistry and their sources in the Hubei Danjiangkou Reservoir, China].

Water temperature, pH, EC, TDS, ORP, Si and major anions (Cl- , NO3- and SO4(2-)) and major cations (Na+, K+, Ca2+ and Mg2+) in the Danjiangkou Reservoir, the water source area of the Middle Route of the South to North Water Transfer Project of China were monitored during the period of 2004-2006. Analysis of variance (ANOVA) and principal component analysis (PCA) were performed to explore their seasonal variations and origins. The results show that the water is slightly alkaline with an average pH ranging from 7.9 to 8.4. The water is HCO3- -Ca type with low mineralized degree, and its total dissolved solid ranges from 174.6-209.1 mg x L(-1). The major ions range are as follows: Cl-, from (4.0 +/- 0.5) mg x L(-1) to (6.9 +/- 1.8) mg x L(-1); NO3-, from (4.6 +/- 0.9) mg x L(-1) to (6.8 +/- 1.7) mg x L(-1); SO4(2-), from (24.3 +/- 2.7) mg x L(-1) to (35.4 +/- 6.9) mg x L(-1); HCO3-, from (133.0 +/- 11.7) mg x L(-1) to (153.5 +/- 29.6) mg x L(-1); Na+, from (2.0 +/- 0.3) mg x L(-1) to (5.3 +/- 1.0) mg x L(-1); K+, from (0.7 +/- 0.09) mg x L(-1) to (1.6 +/- 0.7) mg x L(-1); Ca2+, from (33.0 +/- 2.1) mg x L(-1) to (46.6 +/- 0.8) mg x L(-1); Mg2+, from (8.0 +/- 2.5) mg x L(-1) to (10.5 +/- 3.2) mg x L(-1). Statistical analyses indicate that the water quality variables display significant seasonal differences except HCO3 and Si. In general, major ion concentrations in flood season are relatively lower due to the dilution of precipitation. HCO3- accounts for 75%-88% of the total major anions, while Ca2+ and alkali-earth metals (Ca2+ + Mg2+) account for 60%-80% and 87%-96% of the total major cations respectively, reflecting that carbonic acid weathering is the main proton producer in the water. The major ions have no adverse effects on human according to water drinking quality guidelines of China and WHO.