Long-Term Water Quality Patterns in an Estuarine Reservoir and the Functional Changes in Relations of Trophic State Variables Depending on the Construction of Serial Weirs in Upstream Reaches

Water quality degradation is one of the major problems with artificial lakes in estuaries. Long-term spatiotemporal patterns of water quality in a South Korean estuarine reservoir were analyzed using seasonal datasets from 2002 to 2020, and some functional changes in relations of trophic state variables due to the construction of serial weirs in the upper river were also investigated. A total of 19 water quality parameters were used for the study, including indicators of organic matter, nutrients, suspended solids, water clarity, and fecal pollution. In addition, chlorophyll-a (CHL-a) was used to assess algal biomass. An empirical regression model, trophic state index deviation (TSID), and principal component analysis (PCA) were applied. Longitudinal fluctuations in nutrients, organic matter, sestonic CHL-a, and suspended solids were found along the axis of the riverine (Rz), transition (Tz), and lacustrine zones (Lz). The degradation of water quality was seasonally caused by resuspension of sediments, monsoon input due to rainfall inflow, and intensity of Asian monsoon, and was also related to intensive anthropic activities within the catchment. The empirical model and PCA showed that light availability was directly controlled by non-algal turbidity, which was a more important regulator of CHL-a than total nitrogen (TN) and total phosphorus (TP). The TSID supported our hypothesis on the non-algal turbidity. We also found that the construction of serial upper weirs influenced nutrient regime, TSS, CHL-a level, and trophic state in the estuarine reservoir, resulting in lower TP and TN but high CHL-a and high TN/TP ratios. The proportions of both dissolved color clay particles and blue-green algae in the TSID additionally increased. Overall, the long-term patterns of nutrients, suspended solids, and algal biomass changed due to seasonal runoff, turnover time, and reservoir zones along with anthropic impacts of the upper weir constructions, resulting in changes in trophic state variables and their mutual relations in the estuarine reservoir.

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Multivariate Statistical Analysis of Water Quality and Trophic State in an Artificial Dam Reservoir

Water ◽

10.3390/w13020186 ◽

2021 ◽

Vol 13 (2) ◽

pp. 186

Author(s):

Md Mamun ◽

Ji Yoon Kim ◽

Kwang-Guk An

Keyword(s):

Water Quality ◽

Trophic State ◽

Suspended Solids ◽

Oxygen Demand ◽

Quality Parameters ◽

Water Quality Parameters ◽

Trophic State Index ◽

Multivariate Statistical ◽

Chl A ◽

State Index

Paldang Reservoir, located in the Han River basin in South Korea, is used for drinking water, fishing, irrigation, recreation, and hydroelectric power. Therefore, the water quality of the reservoir is of great importance. The main objectives of this study were to evaluate spatial and seasonal variations of surface water quality in the reservoir using multivariate statistical techniques (MSTs) along with the Trophic State Index (TSI) and Trophic State Index deviation (TSID). The empirical relationships among nutrients (total phosphorus, TP; total nitrogen, TN), chlorophyll-a (CHL-a), and annual variations of water quality parameters were also determined. To this end, 12 water quality parameters were monitored monthly at five sites along the reservoir from 1996 to 2019. Most of the parameters (all except pH, dissolved oxygen (DO), and total coliform bacteria (TCB)) showed significant spatial variations, indicating an influence of anthropogenic activities. Principal component analysis combined with factor analysis (PCA/FA) suggested that the parameters responsible for water quality variations were primarily correlated with nutrients and organic matter (anthropogenic), suspended solids (both natural and anthropogenic), and ionic concentrations (both natural and anthropogenic). Stepwise spatial discriminant analysis (DA) identified water temperature (WT), DO, electrical conductivity (EC), chemical oxygen demand (COD), the ratio of biological oxygen demand (BOD) to COD (BOD/COD), TN, TN:TP, and TCB as the parameters responsible for variations among sites, and seasonal stepwise DA identified WT, BOD, and total suspended solids (TSS) as the parameters responsible for variations among seasons. COD has increased (R2 = 0.63, p < 0.01) in the reservoir since 1996, suggesting that nonbiodegradable organic loading to the water body is rising. The empirical regression models of CHL-a-TP (R2 = 0.45) and CHL-a-TN (R2 = 0.27) indicated that TP better explained algal growth than TN. The mean TSI values for TP, CHL-a, and Secchi depth (SD) indicated a eutrophic state of the reservoir for all seasons and sites. Analysis of TSID suggested that blue-green algae dominated the algal community in the reservoir. The present results show that a significant increase in algal chlorophyll occurs during spring in the reservoir. Our findings may facilitate the management of Paldang Reservoir.

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Assessment of Spatial Distribution of Algal Biomass in a Subtropical Lake in China by Modeling of Landsat ETM+ Data Coupled with Field Data

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.522-524.12 ◽

2014 ◽

Vol 522-524 ◽

pp. 12-20

Author(s):

Wan Min Ni ◽

Jiang Ying Zhang ◽

Teng Da Ding ◽

Jia Guo Qi

Keyword(s):

Water Quality ◽

Regression Models ◽

Trophic State ◽

Vegetation Index ◽

Chl A ◽

Subtropical Lake ◽

Multiple Regression Models ◽

Remote Sensing Techniques

The objective of this research is to construct an efficient way of monitoring water quality and assessing trophic state using remote sensing techniques in Qinshan Lake of Hangzhou, China. Two Landsat ETM+ images were acquired and simultaneous in situ measurements, sampling and analysis were conducted. Results of the study indicated that the ratio of ETM+1/ETM+3 was the most effective single band in estimating chlorophyll-a (Chl-a), followed by normalized ratio vegetation index (NRVI). Two multiple regression models with determination coefficients were further constructed between logarithmically transformed Chl-a and the combination of ETM+1/ETM+3, ETM+2/ETM+3, and ETM+3/ETM+4 of ten sample sites. The resulting models, Log (Chl-a)=1.65 + 0.87*(ETM+1 / ETM+3) 3.39*(ETM+2 / ETM+3) + 0.89*(ETM+3 / ETM+4), and Log (Chl-a)=2.94 1.37*(ETM+1 / ETM+3) + 0.40*(ETM+2 / ETM+3) 0.20*(ETM+3 / ETM+4), both showed strong ability to evaluate the distribution of Chl-a, with R2 of 0.72 and 0.92, respectively. Then two trophic state maps generated for Qinshan Lake using this model could identify zones with a higher potential for eutrophication, which turned out to be an appropriate method for synoptic monitoring of water quality in lakes. Similar modeling can be made for any given subtropical lake, to provide rapid and long term assessment of water quality and also useful information for decision making.

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Trophic Responses of the Asian Reservoir to Long-Term Seasonal and Interannual Dynamic Monsoon

Water ◽

10.3390/w12072066 ◽

2020 ◽

Vol 12 (7) ◽

pp. 2066 ◽

Cited By ~ 1

Author(s):

Md Mamun ◽

Ji Yoon Kim ◽

Kwang-Guk An

Keyword(s):

Trophic State ◽

Suspended Solids ◽

Light Attenuation ◽

Algal Growth ◽

Water Clarity ◽

Algal Community ◽

Trophic State Index ◽

Chl A ◽

Blue Green Algae

The main objectives of the study were to determine the trophic response of the temperate reservoir to seasonal and interannual variabilities of monsoon inorganic solids and nutrients along the gradients of the morphologically complex Asian reservoir using long-term datasets between 2000–2018. Nutrient regime (total nitrogen—TN, total phosphorus—TP), total suspended solids (TSS), and chlorophyll-a (CHL-a) were primarily affected by an intensity of summer monsoon and the longitudinal structure of riverine (Rz), transitional (Tz), and lacustrine (Lz) zone. The reservoir is a nitrogen-rich system and the phosphorus content of the water was relatively low, and it had low mean N:P ratios (<40), implying a P-limiting system. The Lz was a highly P-limited zone in comparison to Rz and Tz zone during both drought (2015) and flood year (2011). The TP content was higher in the mainstem (S3) than the embankment (S4 and S6) of the reservoir due to the monsoon river inputs of the nutrients. Nonparametric Mann–Kendall tests indicated that TP decreased over the long-term years in the Rz, while it did not show any trend in Tz, Lz, IT1, and IT2. TN showed an increasing trend in Rz, Tz, Lz, and IT2 except for IT1. The empirical regression model for chlorophyll nutrients showed that CHL-a had a strong positive relationship with TP (R2 = 0.67, p < 0.01) than TN (R2 = 0.06, p < 0.01), supporting the view that algal growth in lentic systems responds to TP enrichment and TP may provide a reliable basis for predicting algal biomass. The seasonality of CHL-a and TP showed a monomodal pattern and indicates that summer TP influences summer algal growth in Tz, Lz, and IT2. The water clarity (SD) of the reservoir was significantly (p < 0.01) influenced by TP (R2 = 0.62), TSS (R2 = 0.67), and CHL-a (R2 = 0.68) rather than TN (R2 = 0.10). The non-algal light attenuation coefficient (Kna) was determined mainly by suspended solids and the monsoon hydrology. The trophic state was much higher when assessments were based on TSI (CHL-a) than on TSI (TP) and TSI (SD). TSI (CHL-a) indicated the eutrophic state of the reservoirs except for the zone of Lz during the premonsoon season. Analysis of trophic state index deviation (TSID) suggested that the blue-green algae dominated the algal community, and the effects of non-algal turbidity and zooplankton grazing were minor in the reservoir.

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Suspended particles in the drinking water of two distribution systems

Water Science & Technology Water Supply ◽

10.2166/ws.2001.0089 ◽

2001 ◽

Vol 1 (4) ◽

pp. 237-245 ◽

Cited By ~ 12

Author(s):

V. Gauthier ◽

B. Barbeau ◽

R. Millette ◽

J.-C. Block ◽

M. Prévost

Keyword(s):

Water Quality ◽

Drinking Water ◽

Organic Matter ◽

Distribution System ◽

Distribution Systems ◽

Suspended Solids ◽

Suspended Particles ◽

Raw Water ◽

Remote Locations ◽

Dissolved Matter

The concentrations of suspended particles were measured in the drinking water of two distribution systems, and the nature of these particles documented. The concentrations of particulate matter were invariably found to be small (maximum 350 μg/L). They are globally in the very low range in comparison with dissolved matter concentrations, which are measured in several hundreds of mg/L. Except during special water quality events, such as turnover of the raw water resource, results show that organic matter represents the most important fraction of suspended solids (from 40 to 76%) in treated and distributed water. Examination of the nature of the particles made it possible to develop several hypotheses about the type of particles penetrating Montreal's distribution system during the turnover period (algae skeleton, clays). These particles were found to have been transported throughout the distribution systems quite easily, and this could result in the accumulation of deposits if their surface charge were ever even slightly destabilised, or if the particles were to penetrate the laminar flow areas that are fairly typical of remote locations in distribution systems.

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Temporal and Spatial Variations of Chlorophyll a Concentration and Eutrophication Assessment (1987–2018) of Donghu Lake in Wuhan Using Landsat Images

Water ◽

10.3390/w12082192 ◽

2020 ◽

Vol 12 (8) ◽

pp. 2192

Author(s):

Xujie Yang ◽

Yan Jiang ◽

Xuwei Deng ◽

Ying Zheng ◽

Zhiying Yue

Keyword(s):

Remote Sensing ◽

Water Quality ◽

Chlorophyll A ◽

Dynamic Monitoring ◽

Water Quality Parameter ◽

Landsat Images ◽

Chl A ◽

Donghu Lake ◽

Cubic Model

Chlorophyll a (Chl-a) concentration, which reflects the biomass and primary productivity of phytoplankton in water, is an important water quality parameter to assess the eutrophication status of water. The band combinations shown in the images of Donghu Lake (Wuhan City, China) captured by Landsat satellites from 1987 to 2018 were analyzed. The (B4 − B3)/(B4 + B3) [(Green − Red)/(Green + Red)] band combination was employed to construct linear, power, exponential, logarithmic and cubic polynomial models based on Chl-a values in Donghu Lake in April 2016. The correlation coefficient (R2), the relative error (RE) and the root mean square error (RMSE) of the cubic model were 0.859, 9.175% and 11.194 μg/L, respectively and those of the validation model were 0.831, 6.509% and 19.846μg/L, respectively. Remote sensing images from 1987 to 2018 were applied to the model and the spatial distribution of Chl-a concentrations in spring and autumn of these years was obtained. At the same time, the eutrophication status of Donghu Lake was monitored and evaluated based on the comprehensive trophic level index (TLI). The results showed that the TLI (∑) of Donghu Lake in April 2016 was 63.49 and the historical data on Chl-a concentration showed that Donghu Lake had been eutrophic. The distribution of Chl-a concentration in Donghu Lake was affected by factors such as construction of bridges and dams, commercial activities and enclosure culture in the lake. The overall distribution of Chl-a concentration in each sub-lake was higher than that in the main lake region and Chl-a concentration was highest in summer, followed by spring, autumn and winter. Based on the data of three long-term (2005–2018) monitoring points in Donghu Lake, the matching patterns between meteorological data and Chl-a concentration were analyzed. It revealed that the Chl-a concentration was relatively high in warmer years or rainy years. The long-term measured data also verified the accuracy of the cubic model for Chl-a concentration. The R2, RE and RMSE of the validation model were 0.641, 2.518% and 22.606 μg/L, respectively, which indicated that it was feasible to use Landsat images to retrieve long-term Chl-a concentrations. Based on longitudinal remote sensing data from 1987 to 2018, long-term and large-scale dynamic monitoring of Chl-a concentrations in Donghu Lake was carried out in this study, providing reference and guidance for lake water quality management in the future.

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Interannual and long-term changes in the trophic state of a multibasin lake: effects of morphology, climate, winter aeration, and beaver activity

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/cjfas-2015-0249 ◽

2016 ◽

Vol 73 (3) ◽

pp. 445-460 ◽

Cited By ~ 1

Author(s):

Dale M. Robertson ◽

William J. Rose ◽

Paul C. Reneau

Keyword(s):

Water Quality ◽

Trophic State ◽

Secchi Depth ◽

Climatic Changes ◽

Main Flow ◽

Temperature And Precipitation ◽

Air Temperatures ◽

Long Term Changes ◽

P Sources

Little St. Germain Lake (LSG), a relatively pristine multibasin lake in Wisconsin, USA, was examined to determine how morphologic (internal), climatic (external), anthropogenic (winter aeration), and natural (beaver activity) factors affect the trophic state (phosphorus, P; chlorophyll, CHL; and Secchi depth, SD) of each of its basins. Basins intercepting the main flow and external P sources had highest P and CHL and shallowest SD. Internal loading in shallow, polymictic basins caused P and CHL to increase and SD to decrease as summer progressed. Winter aeration used to eliminate winterkill increased summer internal P loading and decreased water quality, while reductions in upstream beaver impoundments had little effect on water quality. Variations in air temperature and precipitation affected each basin differently. Warmer air temperatures increased productivity throughout the lake and decreased clarity in less eutrophic basins. Increased precipitation increased P in the basins intercepting the main flow but had little effect on the isolated deep West Bay. These relations are used to project effects of future climatic changes on LSG and other temperate lakes.

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Temporal Effects of Groundwater on Physical and Biotic Components of a Karst Stream

Water ◽

10.3390/w11061299 ◽

2019 ◽

Vol 11 (6) ◽

pp. 1299 ◽

Cited By ~ 1

Author(s):

Tao Tang ◽

Shuhan Guo ◽

Lu Tan ◽

Tao Li ◽

Ryan M. Burrows ◽

...

Keyword(s):

Water Temperature ◽

Algal Biomass ◽

Groundwater Discharge ◽

Stream Network ◽

Lotic Ecosystems ◽

Chl A ◽

Discharge Water ◽

Downstream Reach ◽

Insight Into

Although most lotic ecosystems are groundwater dependent, our knowledge on the relatively long-term ecological effects of groundwater discharge on downstream reaches remains limited. We surveyed four connected reaches of a Chinese karst stream network for 72 consecutive months, with one reach, named Hong Shi Zi (HSZ), evidently affected by groundwater. We tested whether, compared with other reaches, HSZ had (1) milder water temperature and flow regimes, and (2) weaker influences of water temperature and flow on benthic algal biomass represented by chlorophyll a (Chl. a) concentrations. We found that the maximum monthly mean water temperature in HSZ was 0.6 °C lower than of the adjacent upstream reach, and the minimum monthly mean water temperature was 1.0 °C higher than of the adjacent downstream reach. HSZ had the smallest coefficient of variation (CV) for water temperature but the largest CV for discharge. Water temperature and discharge displayed a significant 12-month periodicity in all reaches not directly groundwater influenced. Only water temperature displayed such periodicity in HSZ. Water temperature was an important predictor of temporal variation in Chl. a in all reaches, but its influence was weakest in HSZ. Our findings demonstrate that longer survey data can provide insight into groundwater–surface water interactions.

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Assessing the Trend of the Trophic State of Lake Ladoga Based on Multi-Year (1997–2019) CMEMS GlobColour-Merged CHL-OC5 Satellite Observations

Sensors ◽

10.3390/s20236881 ◽

2020 ◽

Vol 20 (23) ◽

pp. 6881

Author(s):

Augustine-Moses Gaavwase Gbagir ◽

Alfred Colpaert

Keyword(s):

Water Quality ◽

Trophic State ◽

Current Knowledge ◽

Management Strategies ◽

Paper Mill ◽

Warming Trend ◽

Satellite Observations ◽

Lake Ladoga ◽

General Reference ◽

Chl A

The trophic state of Lake Ladoga was studied during the period 1997–2019, using the Copernicus Marine Environmental Monitoring Service (CMEMS) GlobColour-merged chlorophyll-a OC5 algorithm (GlobColour CHL-OC5) satellite observations. Lake Ladoga, in general, is mesotrophic but certain parts of the lake have been eutrophic since the 1960s due to the discharge of wastewater from industrial, urban, and agricultural sources. Since then, many ecological assessments of the Lake’s state have been made. These studies have indicated that various changes are taking place in the lake and continuous monitoring of the lake is essential to update the current knowledge of its state. The aim of this study was to assess the long-term trend in chl-a in Lake Ladoga. The results showed a gradual reduction in chl-a concentration, indicating a moderate improvement. Chl-a concentrations (minimum-maximum values) varied spatially. The shallow southern shores did not show any improvement while the situation in the north is much better. The shore areas around the functioning paper mill at Pitkäranta and city of Sortavala still show high chl-a values. These findings provide a general reference on the current trophic state of Lake Ladoga that could contribute to improve policy and management strategies. It is assumed that the present warming trend of surface water may result in phytoplankton growth increase, thus partly offsetting a decrease in nutrient load. Precipitation is thought to be increasing, but the influence on water quality is less clear. Future studies could assess the current chemical composition to determine the state of water quality of Lake Ladoga.

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Periods of Extreme Shallow Depth Hinder but Do Not Stop Long-Term Improvements of Water Quality in Lake Apopka, Florida (USA)

Water ◽

10.3390/w11030538 ◽

2019 ◽

Vol 11 (3) ◽

pp. 538 ◽

Cited By ~ 2

Author(s):

Gaohua Ji ◽

Karl Havens

Keyword(s):

Water Quality ◽

Eutrophic Lake ◽

Water Levels ◽

Shallow Depth ◽

Benthivorous Fish ◽

Chl A ◽

Lake Apopka ◽

Toxic Cyanobacteria ◽

Long Term Trends

We recently documented that during times of extreme shallow depth, there are severe effects on the water quality of one of the largest shallow lakes in the southeastern USA—Lake Apopka. During those times, total phosphorus (TP), total nitrogen (TN), chlorophyll-a (Chl-a) and toxic cyanobacteria blooms increase, and Secchi transparency (SD) declines. The lake recovers when water levels rise in subsequent years. In this paper, we determined whether extreme shallow depth events, particularly when they re-occur frequently, can stop the long-term recovery of a shallow eutrophic lake undergoing nutrient reduction programs. Apopka is an ideal location for this case study because the State of Florida has spent over 200 million USD in order to reduce the inputs of P to the lake, to build large filter marshes to treat the water, and to remove large quantities of benthivorous fish that contribute to internal P loading. We obtained data from 1985 to 2018, a period that had relatively stable water levels for nearly 15 years, and then three successive periods of extreme shallow depth, and we examined the long-term trends in TP, TN, Chl-a, and SD. There were significant decreasing trends in all of these water quality variables, and even though water quality deteriorated during periods of extreme shallow depth, and reduced the slope of the long-term trends, it did not stop the recovery. However, in the future, if climate change leads to more frequent shallow depth events, which in lakes such as Apopka, result in the concentration of water and nutrients, it is unclear whether the resilience we document here will continue, vs. the lake not responding to further nutrient input reductions.

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Spectral characterization of dissolved organic matter along trophic gradients: Potential indicators of eutrophication of plateau lakes in Southwest China

10.21203/rs.3.rs-573085/v1 ◽

2021 ◽

Author(s):

Yuying Guan ◽

Ruiming Han ◽

Nannan Jia ◽

Da Huo ◽

Gongliang Yu

Keyword(s):

Water Quality ◽

Organic Matter ◽

Optical Properties ◽

Dissolved Organic Matter ◽

Trophic State ◽

Intensity Increase ◽

Optical Parameters ◽

Trophic State Index ◽

Main Role ◽

Neural Network Prediction

Abstract Dissolved organic matter (DOM) acts as a chemical intermediary between terrestrial and lacustrine ecosystems and significantly affects the structure and function of lakes. The optical characteristics of DOM have been widely used to estimate the water quality. However, little is known about its absorption and fluorescence under different trophic states. Especially, comparative research is needed among gradient eutrophic level of plateau lakes when considering their special characteristics. A total of 119 water samples were collected in the Erhai watershed from November 2018 to July 2019 to investigate the optical properties of DOM depending on the trophic state using ultraviolet–visible spectroscopy and parallel factor analysis of the excitation–emission matrix. The water quality conditions in the Erhai watershed were classified using the trophic state index (TSI; 31 < TSI < 67). The DOM is largely autochthonous and includes tyrosine-like protein (C1), tryptophan-like protein (C2), and humic-like compounds (C3). Except for an apparent trend of decreasing slope ratio (SR) (p < 0.01), both absorption coefficient at 254 nm and fluorescence intensity increase with the rising trophic state (p < 0.01). In this study, new models (R2aCDOM(254) = 0.762; R2 Fn(355) = 0.705, p < 0.01) basing on significant correlations between the TSI and aCDOM(254) and Fn(355) were established to predict the trophic state. The results of this study demonstrate that the effects of nutrients and environmental factors (pH and water temperature) on DOM vary depending on the trophic state and that the pH plays the main role in DOM production. Our analyses highlight the importance of DOM in aquatic ecosystems and the correlation between TSI and the optical properties of DOM. Our research unmasks the strong linkage between optical parameters of DOM and freshwater quality by applying neural network prediction.

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