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1.
Huan Jing Ke Xue ; 40(7): 3039-3048, 2019 Jul 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854701

RESUMO

The ecological problems due to reservoir construction are causing unprecedented concern. To reveal the differences in organic carbon distribution characteristics and sediment sources of total organic carbon (TOC) between the old and new reservoirs, water samples, and sediment samples from reservoirs constructed in the three different periods of Miaowei, Gongguoqiao, and Dachaoshan were collected in November 2017. The temperature (T), dissolved oxygen (DO), TOC, redox potential (ORP), total nitrogen (TN), and total phosphorus (TP) of the water samples were measured. The isotopes 15N and 13C were used as indicators with IsoSource software to analyze the contributions of TOC sources and their source materials to the corresponding reservoir sediments, in order to explore the carbon cycle mechanism and evolution mode of reservoir. The results showed that the average concentrations of organic carbon in the waters of the Miaowei, Gongguoqiao, and Dachaoshan Reservoirs were 0.95 mg·L-1, 1.97 mg·L-1, and 4.64 mg·L-1, respectively. The range of organic carbon content in the corresponding sediments was 4.41-81.63 g·kg-1, 18.30-28.42 g·kg-1, and 9.16-14.46 g·kg-1, respectively. The cascade construction of the reservoirs resulted in a difference between the sediment sources of the new and old reservoirs and the surrounding recharge area, meaning that the TOC of the new and old reservoirs were significantly different. For the TOC of waterbodies, the difference between the thermodynamic state of water and dissolved oxygen indirectly affects the distribution trend of TOC. The sediments mainly reflect the influence of source elements, that is, the ability of the sedimentary environment to preserve organic matter was the main cause of the vertical distribution of DCS, MV, and GGQ sediments. In the evolution mode of cascade reservoir, the research shows that it can be preliminarily set as three stages. Firstly, due to the short age of MV, it is in the first stage and mainly accumulates the TOC from the upstream. GGQ is longer than the age of MV, and it is mainly used to decompose the upstream TOC, so it is defined as in the second stage. Finally, as an old reservoir, DCS mainly accumulates TOC sources around the reservoir, which can be regarded as the third stage.

2.
Huan Jing Ke Xue ; 40(6): 2753-2763, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854668

RESUMO

In order to study the relationship between the vertical distribution of nutrients and bacterial community structures in sediment interstitial waters of stratified reservoirs with different water temperatures, MiSeq high-throughput sequencing was used to analyze and compare the structural characteristics of sediment bacterial communities after reservoirs were built. Additionally, redundancy analysis (RDA) was used to assess the bacterial communities and environmental factors with Cannoco software. The results showed that the temperature difference between the surface and bottom layer of the Xiaowan Reservoir was 3.3℃, and the maximum thermal gradient was 0.2℃·m-1; thus, it was a typical stratified reservoir. The temperature difference between the surface and bottom layer of the Manwan Reservoir was 0.1℃; thus, it was a typical mixed reservoir. The average concentrations of NH4+-N and NO3--N in sediment interstitial waters of the Xiaowan Reservoir were 2.233 mg·L-1 and 0.030 mg·L-1, while those of Manwan were 2.569 mg·L-1 and 0.016 mg·L-1, respectively. In the different reservoirs, the concentrations of NH4+-N showed upward trends, and while variation of NO3--N was not obvious, the content of NO3--N reached a minimum value in the deep layer. In comparisons between reservoirs, only NO3--N showed a significant difference, in which Xiaowan had obviously higher concentrations than Manwan. The bacterial community structures in the Xiaowan and Manwan reservoir sediments had the same dominant bacteria at the phylum, class, and genus levels. The differences of water temperature stratification had no significant effect on nutrients and microorganisms in the sediments. Under the influence of other factors, the denitrifying bacteria in the Manwan Reservoir sediments were more abundant than those in the Xiaowan Reservoir, and the nitrifying bacteria and anammox bacteria in the Xiaowan Reservoir sediments were more abundant than those in the Manwan Reservoir. In the same reservoir, the denitrifying bacteria in the bottom of the sediments were more abundant, and the organic degradation bacteria, nitrifying bacteria, anammox bacteria, and phosphate-solubilizing bacteria were less abundant in this zone. These trends contributed to the differences of nutrients vertically in the different reservoirs.


Assuntos
Bactérias/classificação , Água Doce/química , Sedimentos Geológicos/microbiologia , Temperatura Ambiente , Microbiologia da Água , China , Água Doce/microbiologia
3.
Huan Jing Ke Xue ; 40(11): 4944-4952, 2019 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854560

RESUMO

The construction of the Three Gorges Reservoir has had certain effects on the ecological environment of the water and serious phytoplankton blooms have occurred in its tributary embayment. To explore the spatial distribution of nitrogen and phosphorus nutrients and chlorophyll-a in different tributaries of the Three Gorges Reservoir, a water quality study (June 2018) was conducted in the Xiangxi River, Shengnongxi River, and Daning River of the Three Gorges Reservoir. The results showed that the average TN in the three tributaries was 1.86 mg·L-1, 1.90 mg·L-1, and 1.43 mg·L-1, respectively, and average TP was 0.09 mg·L-1, 0.07 mg·L-1, and 0.05 mg·L-1, respectively. Single-factor ANOVA analysis showed that the spatial difference in TN was significant and occurred in the following order:Shennongxi River > Xiangxi River > Daning River. There were significant differences in the spatial distribution of TP, which were in the order off Xiangxi River > Shennongxi River > Daning River. The mean concentrations of chlorophyll-a in the three tributaries was 6.41 µg·L-1, 21.39 µg·L-1, and 9.85µg·L-1, respectively. The results from the Pearson correlation analysis, showed that chlorophyll-a concentrations were closely related to TP distribution in all tributaries, but Zeu/Zmix was also correlated with the distribution of chlorophyll-a in the Shennongxi River and Daning River. The ratio of TN and TP concentrations was 22.36, 26.76, and 28.6, respectively, which revealed that TP is a critical and limiting factor affecting phytoplankton growth in its tributary embayment.


Assuntos
Clorofila A , Rios , Sais , China , Clorofila , Monitoramento Ambiental , Eutrofização , Inundações , Nitrogênio , Nutrientes , Fósforo , Estações do Ano
4.
Huan Jing Ke Xue ; 40(4): 1779-1787, 2019 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-31087919

RESUMO

Construction of cascade reservoirs in Lancang River had a certain influence on the ecological water environment of the basin, dividing the water into natural reaches and reservoir reaches. To explore the impact of the cascade reservoirs on the ecological environment, the nutrient and the chlorophyll a distribution data were measured in the natural reaches, reservoir reaches, and tributaries in June 2017. The results showed that the TN ranged from 0.37 to 1.22 mg·L-1, with an average of 0.70 mg·L-1, and the TP ranged from 0.01 to 0.19 mg·L-1, with an average of 0.04 mg·L-1. One-way ANOVA analysis showed significant spatial differences in the TN, with the TN concentration following the order tributaries > reservior reaches > natural reaches. However, the TP concentration did not show a significant trend. The chlorophyll a concentration varied from 2.6 to 10.2 µg·L-1, with a mean of 5.8 µg·L-1. Pearson correlation analysis showed significant relationships between the chlorophyll a concentration and the TP, water temperature, and Zeu/Zmix. The relationship between chlorophyll a and Zeu/Zmix was particularly significant, which indicated the Zeu/Zmix caused by thermal stratification may be the key factor influencing the growth of phytoplankton.


Assuntos
Clorofila A/análise , Monitoramento Ambiental , Rios/química , China , Nitrogênio/análise , Fósforo/análise
5.
Huan Jing Ke Xue ; 40(2): 640-648, 2019 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-30628326

RESUMO

To study the mechanism of phosphorus cycling in sediment during the redox cycle, changes in physicochemical properties of overlying water and various forms of phosphorus in sediments were investigated as a way to quantify the redistribution of phosphorus. Additionally, the effect of the release flux of phosphate from sediments under controlled redox conditions was analyzed. The results showed that the redox potential Eh and the pH system, sulfur system, carbon system, and iron-related changes exhibited periodicity and played an important role in explaining the migration and transformation mechanism in the interface phosphorus of the sediment-water phase. During the redox cycle, the phosphorus content of each species varied with the redox conditions and time. Because of this, quantitative analysis based on changes in water-sediment phosphorus could be obtained. Reducible phosphorus (BD-P) and iron-aluminum-bound phosphorus (NaOH-rP) were reversibly redistributed into weakly adsorbed phosphorus (NH4Cl-P), polyphosphorus/organophosphorous (NaOH-nrP), residual phosphorus (Rest-P), and interstitial water-soluble active phosphorus (SRP). Additionally, 93.7% of phosphorus in the sediment was not released into the water phase during the reduction reaction. The 92% of change in the overlying water total phosphorus (TP) was the SRP of overlying water, which showed that the exchange of the sediment-water phase were mainly soluble active phosphorus in this cycle. According to Fick's First Law, the maximum phosphorus flux was 0.58 mg·(m2·d)-1 during reduction and 0.16-0.22 mg·(m2·d)-1 on day seven of the oxidation phase. In the oxidation stage, the diffusion flux decreased with time, while the opposite trend occurred in the reduction reaction. This indicated that the anaerobic state accelerated the diffusion of phosphorus in sediments, and that oxygen exposure decreased the phosphorus flux in sediments.

6.
Huan Jing Ke Xue ; 39(2): 765-773, 2018 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964840

RESUMO

The process of phytoplankton succession and change in primary productivity are directly determined by the seasonal variations in nutrients in tributary bays of channel reservoirs. This study aimed at analyzing the effects of the main nutrient sources on seasonal distribution of nutrients in Xiangxi Bay based on the field data collected in 2010 and 2011. The tracing inorganic ions were Cl- and Na+ that showed significant differences (P<0.01) between the mainstream and the tributary. The nutrient contribution rates of different sources were calculated by the binary linear model. The results showed that the nutrient contribution rate of the mainstream was more than 75% during the dry season and the impoundment period. The intrusion of the mainstream was the main source of nutrients in Xiangxi Bay. The difference in the contribution rates between the mainstream and the upstream decreased during the pre-flood drawdown period and the flood season. The concentration of total phosphorus was higher in the upstream, while the concentration of total nitrogen was higher in the mainstream. The patterns of density currents were different and the nutrient contribution rates of different sources changed accordingly. Therefore, the nutrients of Xiangxi Bay changed regularly in different operation periods of the Three Gorges Reservoir.


Assuntos
Baías , Nitrogênio/análise , Fósforo/análise , Fitoplâncton/crescimento & desenvolvimento , Estações do Ano , China , Monitoramento Ambiental
7.
Huan Jing Ke Xue ; 39(5): 2126-2134, 2018 May 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965512

RESUMO

A field survey was carried out to investigate the diffusive fluxes of nitrogen and phosphorus from sediment in the natural river areas and cascaded reservoirs in the Lancang River Basin from February through March in 2017. In the natural river areas, the mean value of total nitrogen (TN) concentrations in the sediment pore water was about 15.254 mg ·L-1, and the total phosphorus (TP) was only 0.654 mg ·L-1; while in the reservoirs, the mean value of TN and TP were 6.577 mg ·L-1 and 1.432 mg ·L-1, respectively. Both nutrients in the overlying water were less than that in the sediment pore water. The mean diffusive flux of total dissolved nitrogen (DTN) was almost 2.117 mg ·(m2 ·d)-1 in the natural river areas, and the mean value of total dissolved phosphorus (DTP) was 0.044 mg ·(m2 ·d)-1, while the mean value of DTN and DTP were 0.785 mg ·(m2 ·d)-1 and 0.053 mg ·(m2 ·d)-1 in the reservoirs, respectively. The TN content reaches the maximum in the overlying water-interstitial water vertical surface sediments. It was concluded that cascaded hydropower had greatly changed the nutrient exchange between the sediment and overlying water. Different hydrodynamics and varied chemical environments in the sediment could be additional causes.

8.
Huan Jing Ke Xue ; 39(8): 3649-3659, 2018 Aug 08.
Artigo em Chinês | MEDLINE | ID: mdl-29998671

RESUMO

In order to explore the bacterioplankton diversity community structure in the Lancang River basin, as well as to study the relationship between the bacterial diversity and environmental factors, MiSeq high-throughput sequencing was used to analyze and compare the bacterial diversity and community composition of samples in February 2017. Furthermore, Pearson correlation analysis and redundancy analysis (RDA) were used to identify the key environmental factors for the change of bacterial community structure in the natural river and reservoirs of the Lancang river. The results show that the ACE index and Shannon index of the natural river are higher than those of the reservoir, and the main environmental factors causing the diversity of planktonic bacteria in natural river and reservoir segments are water temperature (WT), dissolved oxygen (DO), turbidity (Tur), permanganate index, pH, and total nitrogen (TN). Overall, 26772 optimized reads were obtained from samples based on the high-throughput sequencing of the V3 and V4 region of the 16S rRNA gene. The bacterial species detected in these samples cover 45 phyla and 965 genera. Taxonomic assignment analysis indicated that Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria are the abundant phyla. Among them, the Proteobacteria content is relatively rich, accounting for 36%-94% of the bacterial community. The predominant groups are α-Proteobacteria, ß-Proteobacteria, and γ-Proteobacteria, at the genus level, with Proteobacteria ratios of 0.39%-21.56%, 0.39%-55.80% and 31.09%-99.18%, respectively. The environmental factors affecting the community structure of planktonic bacteria are different in natural river and reservoir. DO and Tur are the key environmental factors affecting the community structure of planktonic bacteria in the natural river, while the community structure of planktonic bacteria in reservoirs is mainly affected by WT, permanganate index, and TN.


Assuntos
Bactérias/classificação , Biodiversidade , Plâncton/classificação , Rios/microbiologia , China , Filogenia , RNA Ribossômico 16S
9.
Huan Jing Ke Xue ; 39(11): 4964-4971, 2018 Nov 08.
Artigo em Chinês | MEDLINE | ID: mdl-30628218

RESUMO

The influence of cascade hydropower construction on the migration and transformation of raw material and ecological problems in the Lancang River Basin is of concern to scholars domestically and internationally. Based on stable isotope technology, this study analyzed the spatial distribution of nitrogen in the Lancang River Basin and explained the cause of this distribution. The results showed that the range of dissolved inorganic nitrogen (DIN) was 0.28-0.60mg·L-1, and that of DIN in the downstream area of the Lancang River was 0.39-1.15mg·L-1. The range of suspended particulate matter δ15 N in the upstream area of this river was 4.52‰-6.72‰, and that in the downstream reservoir section was heavier than that in the upstream reservoir, which varied between 2.3‰ and 11.8‰. This study used Isosource to analyze the source of suspended particulate matter. The results showed that industrial wastewater and sewage, soil organic matter, atmospheric sedimentation, and agrochemicals are the main sources of suspended particulate matter, and their respective total contribution rates are 42.43%, 22.38%, 18.16%, and 17.03%. At the same time, the δ15 N of suspended particulate matter in Xiaowan, Manwan, and Dachaosan dams downstream of the Lancang River were influenced by algal assimilation, it leads to a reduction in the number of δ15 N of suspended particles.

10.
Huan Jing Ke Xue ; 38(4): 1393-1402, 2017 Apr 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965140

RESUMO

According to the data collected from the five monitoring sites in front of the dam in Thousand-island Lake in September 2015, the vertical distribution characteristics of dissolved oxygen (DO), water temperature, pH, turbidity, conductivity and phytoplankton were analyzed. The influencing factors of special stratification of DO and vertical distribution of phytoplankton were also discussed. The results showed that:① The vertical distribution of DO presented "the surface is higher than the underlying" mode. DO ranged from 1.95 mg·L-1 to 8.25 mg·L-1 and the average concentration was 5.10 mg·L-1. Low-oxygen zones appeared between 12 m and 20 m and the minimum concentration was 1.95 mg·L-1 at 17 m. The concentration of DO maintained at a high level between 0 m and 12 m and the vertical variance was small. Sudden drop of DO occurred between 12 m and 20 m and there was an anoxic zone (<4.0 mg·L-1). The concentration of DO returned to normal level between 20 m and 38 m. Then it reduced under 38m as the water depth increased. The vertical distribution of pH showed the same trend with that of DO and their sudden change regions appeared in the same zone. ② Vertical phytoplankton biomass displayed significant difference. The phytoplankton biomass of S1, S2 and S3 presented:mid-layer > surface > bottom. But S4, S5 presented:bottom > surface > mid-layer. In addition, the depth between 20 m and 30 m was the best for the growth of phytoplankton. ③ The correlation analysis showed that DO and water temperature in the thermocline were significantly correlative. The range and degree of low-oxygen zones in Thousand-island Lake was determined by physical processes like thermal stratification of water and direct or indirect effects of the plankton. Phytoplankton and DO, pH showed significant negative correlation. The phytoplankton was mainly influenced by turbulent mixing and DO stratification in the surface layer while it was mainly influenced by light intensity at the bottom.


Assuntos
Monitoramento Ambiental , Lagos/química , Oxigênio/análise , Fitoplâncton/crescimento & desenvolvimento , China
11.
Huan Jing Ke Xue ; 37(6): 2149-2157, 2016 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-29964880

RESUMO

In order to study the mechanism of the habitat disturbance of reservoir on algae blooms, some interior control experiments about the feature of algal diversity and the succession of community structure under different temperature disturbance cycle but the same amplitude condition were conducted, based on the intermediate disturbance hypothesis and combined with algal community habitat selection theory and ecological functional groups of algae. The results showed that:① the intermediate disturbance would accelerate the growth of algae and increase their diversity. Under the gradient of the intermediate disturbance group Δ22℃/48h, the diversity of phytoplankton was the highest, and the biomass reached the maximum, however, without absolute dominant algal species. While in the high frequency disturbance group Δ22℃/24h the biodiversity was relatively lower, but the algae biomass was reduced. ② the periodical change of temperature had obvious influence on the succession of the phytoplankton community, and the dominant species also presented certain differences. The succession of the algal advantageous function group followed the basic rule of X1(Chlorella)→J(Scenedesmus)→S1(Phormidium) or X2 (Chlamydomonas), and the community structure also presented a trend that the C/CR type algae took advantage and the superiority was gradually replaced by R type algae. When the high temperature disturbance was frequent, the R type algae (S1) was distinctly ascendant. During the experiment, the community structure was given priority to the C/R strategy algae with no or low disturbance. However, the coexistence of algae with different growth strategies was evident in group Δ22℃/48h. Meanwhile, the S strategy algae (L0) resistant to high temperature stress began to emerge.


Assuntos
Ecossistema , Eutrofização , Microalgas/crescimento & desenvolvimento , Temperatura Ambiente
12.
Environ Monit Assess ; 186(10): 6833-47, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24990348

RESUMO

A comprehensive monitoring program was conducted to investigate the nutrient spatial pattern in the mainstream of the Yangtze River from the Baihetan Dam down to the Three Gorges Dam located at the upper region of the Yangtze River in China. Samples were taken from 33 different sites from July 30 to August 19, 2011. The nutrient patterns of the three representative tributaries of the Three Gorges Reservoir (TGR)--the Modao, the Daning, and the Xiangxi Rivers--were also investigated. The results show that the mainstream of the TGR has a higher concentration of nitrogen and a lower concentration of phosphorus than that of the upper mainstream before the TGR. Moreover, it was found that nitrate-nitrogen (NO3-N) is the main nitrogen component, while particulate phosphorus predominates the total phosphorus (TP). It was found that the three representative tributaries of the TGR have lower total nitrogen (TN) concentrations compared to the corresponding sections of the mainstream TGR. Based on the nutrient spatial pattern, the nutrient flux was calculated. The total fluxes of TN, NO3-N, TP, and orthophosphate (PO4-P) from the upstream reach into the TGR are 2,155.06, 1,674.97, 212.98, and 83.42 t day(-1), respectively. The amount of nutrients imported from the TGR into its tributaries is more than the amount exported. It was determined that the Xiangxi River has the largest net rate of imported nitrogen at 7.66 t day(-1), whereas the Daning River has the largest net rate of imported phosphorus at 1.75 t day(-1). In addition, compared with the nutrients imported from the TGR into its tributaries, the nutrient flux from the upstream reach into the TGR contributes approximately less than 3 %.


Assuntos
Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , China , Fosfatos/análise , Rios/química
13.
Huan Jing Ke Xue ; 34(8): 3049-56, 2013 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-24191547

RESUMO

Frequent blooms have been observed in tributary bays of the Three Gorges Reservoir since its initial filling. In order to identify the primary factor controlling water blooms, some experiments were conducted based on the critical depth theory. In the winter of early 2012, the enclosures on Xiangxi River were built to investigate the mechanism of mixing layer depth (Z(mix)) on algal growth. The length of the enclosures under water was changed in gradient, and the water of each enclosures was injected from Xiangxi River, in which the algal concentration was low and the zooplanktons were filtered out, and then the water was mixed evenly. The results showed that the algae grew quickly in the enclosures with Z(eu)/Z(mix) (the favorable ratio of euphotic depth to mixing depth) > 1, and the maximum density of chlorophyll-a (ChI-a) reached 90 mg x m(-3), otherwise the algae grew slowly. The critical depth theory was appropriate for the experiment, and there was a critical value of Z(eu)/Z(mix). Water bloom will not break out if the Z(eu)/Z(mix) is below the critical value. Based on the critical depth theory, it was found that there was a negative correlation between algal net primary productivity and Z(mix), the lower the Z(mix), the greater the net primary productivity.


Assuntos
Clorofila/análise , Eutrofização , Rios/microbiologia , Baías , China , Clorofila A , Estações do Ano
14.
Huan Jing Ke Xue ; 34(4): 1308-14, 2013 Apr.
Artigo em Chinês | MEDLINE | ID: mdl-23798107

RESUMO

In order to investigate the internal contamination load sources in the Three Gorges Reservoir (TGR), a field sampling campaign was carried out in November and December 2010. Phosphate contents (PO4(3-) -P) were determined in 6 mainstream and 9 estuary sediment cores of sediment-water interface in the TGR. The results showed that the PO4(3-) -P concentrations of pore water in sediments from tributaries and the corresponding overlying water were higher than those from the mainstream. The PO4(3-) -P contents in tributaries and mainstream ranged from 9.59-29.79 microg x L(-1) and 9.01-25.36 microg x L(-1), respectively. Based on calculations using the Fick's First Law, sediments located at GuoJiaba and Xiaojiang estuaries were the 'sink' of P, and the fluxes of sediment PO4(3-) -P were estimated to be -0.63 mg x (m2 x a)(-1) and -0.60 mg x (m2 x a)(-1), respectively. In other areas, PO4(3-) -P diffused from the pore water to the overlying water, and the diffusive fluxes were in the range of 0.15-2.47 mg x (m2 x a)(-1). With the assumption that molecular diffusion was the main process by which nutrients were transported from the pore water to the overlying water and the water body in the TGR was evenly mixed, the contribution of sediment phosphorus to the water body was only -0.011-0.098%. So far, with the Three Gorges Reservoir sediments as the internal contamination load sources, the phosphorous release didn't significantly influence the water quality. The sediments in the TGR may be a large P source in a period of future time after the external P source is controlled efficiently.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/química , Fosfatos/análise , Fósforo/análise , Poluentes Químicos da Água/análise , China , Rios , Estações do Ano , Abastecimento de Água
15.
Huan Jing Ke Xue ; 33(8): 2621-7, 2012 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-23213882

RESUMO

Frequent spring blooms have been observed in tributary bays of Three Gorges Reservoir (TGR) since its initial filling. In order to study Three Gorges Reservoir of nutrients by the River tributaries reverse effect, a well-designed field monitoring plan was conducted. The results show: there are significant intrusions from Three Gorges Reservoir to Xiangxi Bay to the surface, middle and bottom with three forms of intrusion respectively. The unique flow characteristics provide a hydrodynamic background of nutrient distributions of Xiangxi Bay. The average instantaneous fluxes of the input TN and TP of the intrusions from the confluence were 501.92 g x s(-1) and 48.17 g x s(-1), respectively; TN and TP loads originated from intrusions accounted for 43.4% and 21.5%, respectively to total amount in the whole year. The study shows that intrusion of the total nitrogen input, a large proportion of total phosphorus, and reducing the pollution loads of tributaries and upper reach basin of Three Gorges Reservoir is the fundamental way to eradicate algal blooms.


Assuntos
Eutrofização , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , Baías , China , Monitoramento Ambiental , Rios , Abastecimento de Água
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