The impacts of global and local change on a tropical lake over forty years

Mapping Intimacies ◽

10.1101/2020.10.21.347393 ◽

2020 ◽

Author(s):

Jemma M. Fadum ◽

Ed K. Hall

Keyword(s):

Total Phosphorus ◽

Trophic State ◽

Inorganic Nitrogen ◽

Secchi Depth ◽

Water Clarity ◽

Physical Structure ◽

Tropical Lake ◽

Dissolved Inorganic Nitrogen ◽

Lake Ecosystems ◽

Algal Productivity

AbstractLakes across the world are experiencing novel trophic states, declining water quality, and altered biogeochemical cycling due to the synergistic impacts of global change and local anthropogenic stressors. In the tropics these changes can be difficult to assess due to a lack of continuous monitoring or documented legacy conditions to serve as a reference for the contemporary lake. Over the last forty years, Lake Yojoa, located in west central Honduras, has shifted from an oligotrophic to mesotrophic ecosystem as evidenced by a loss of water clarity. To assess the changes that have occurred in Lake Yojoa as well as putative drivers for those changes, we compared secchi depth, dissolved inorganic nitrogen, and total phosphorus concentrations between 1979-1983 and today (2018-2020). While we found little change in total phosphorus between legacy and contemporary data, we found concurrent changes to seasonal trends in secchi depth and dissolved inorganic nitrogen (DIN). Seasonal peaks in DIN coincident with mixus suggest that accumulation of ammonium in the hypolimnion during stratification, and release to the epilimnion with mixus maintains algal productivity in what was previously a nutrient-limited, clear water phase, driving a change in the overall trophic state of Lake Yojoa. This impact of seasonal dynamics on the trophic state of the lake illustrates a key distinction in how physical structure and nutrients interact differently in tropical and temperate lake ecosystems and highlights the importance of warm anoxic hypolimnions to the biogeochemistry that governs the trophic state of tropical lake ecosystems.

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APLIKASI CITRA LANDSAT 8 OLI UNTUK IDENTIFIKASI STATUS TROFIK WADUK GAJAH MUNGKUR WONOGIRI, JAWA TENGAH

MAJALAH ILMIAH GLOBE ◽

10.24895/mig.2017.19-2.633 ◽

2017 ◽

Vol 19 (2) ◽

pp. 113

Author(s):

Kusuma Wardani Laksitaningrum ◽

Wirastuti Widyatmanti

Keyword(s):

Chlorophyll A ◽

Total Phosphorus ◽

Trophic State ◽

Water Clarity ◽

Coefficient Of Determination ◽

Physical Factors ◽

Landsat 8 ◽

Trophic State Index ◽

Landsat 8 Oli ◽

State Index

ABSTRAKWaduk Gajah Mungkur (WGM) adalah bendungan buatan yang memiliki luas genangan maksimum 8800 ha, terletak di Desa Pokoh Kidul, Kecamatan Wonogiri, Kabupaten Wonogiri. Kondisi perairan WGM dipengaruhi oleh faktor klimatologis, fisik, dan aktivitas manusia yang dapat menyumbang nutrisi sehingga mempengaruhi status trofiknya. Tujuan dari penelitian ini adalah mengkaji kemampuan citra Landsat 8 OLI untuk memperoleh parameter-parameter yang digunakan untuk menilai status trofik, menentukan dan memetakan status trofik yang diperoleh dari citra Landsat 8 OLI, dan mengevaluasi hasil pemetaan dan manfaat citra penginderaan jauh untuk identifikasi status trofik WGM. Identifikasi status trofik dilakukan berdasarkan metode Trophic State Index (TSI) Carlson (1997) menggunakan tiga parameter yaitu kejernihan air, total fosfor, dan klorofil-a. Model yang diperoleh berdasar pada rumus empiris dari hasil uji regresi antara pengukuran di lapangan dan nilai piksel di citra Landsat 8 OLI. Model dipilih berdasarkan nilai koefisien determinasi (R2) tertinggi. Hasil penelitian merepresentasikan bahwa nilai R2 kejernihan air sebesar 0,813, total fosfor sebesar 0,268, dan klorofil-a sebesar 0,584. Apabila nilai R2 mendekati 1, maka semakin baik model regresi dapat menjelaskan suatu parameter status trofik. Berdasarkan hasil kalkulasi diperoleh distribusi yang terdiri dari kelas eutrofik ringan, eutrofik sedang, dan eutrofik berat yaitu pada rentang nilai indeks 50,051 – 80,180. Distribusi terbesar adalah eutrofik sedang. Hal tersebut menunjukkan tingkat kesuburan perairan yang tinggi dan dapat membahayakan makhluk hidup lain.Kata kunci: Waduk Gajah Mungkur, citra Landsat 8 OLI, regresi, TSI, status trofikABSTRACTGajah Mungkur Reservoir is an artificial dam that has a maximum inundated areas of 8800 ha, located in Pokoh Kidul Village, Wonogiri Regency. The reservoir’s water conditions are affected by climatological and physical factors, as well as human activities that can contribute to nutrients that affect its trophic state. This study aimed to assess the Landsat 8 OLI capabilities to obtain parameters that are used to determine its trophic state, identifying and mapping the trophic state based on parameters derived from Landsat 8 OLI, and evaluating the results of the mapping and the benefits of remote sensing imagery for identification of its trophic state. Identification of trophic state is based on Trophic State Index (TSI) Carlson (1997), which uses three parameters there are water clarity, total phosphorus, and chlorophyll-a. The model is based on an empirical formula of regression between measurements in the field and the pixel values in Landsat 8 OLI. Model is selected on the highest value towards coefficient of determination (R2). The results represented that R2 of water clarity is 0.813, total phosphorus is 0.268, and chlorophyll-a is 0.584. If R2 close to 1, regression model will describe the parameters of the trophic state better. Based on the calculation the distribution consists of mild eutrophic, moderate eutrophic, and heavy eutrophic that has index values from 50.051 to 80.18. The most distribution is moderate eutrophication, and it showed the high level of trophic state and may harm other living beings.Keywords: Gajah Mungkur Reservoir, Landsat 8 OLI satellite imagery, regression, TSI, trophic state

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Distributions of dissolved inorganic nitrogen to estimate trophic state in Jakarta Bay

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/241/1/012023 ◽

2019 ◽

Vol 241 ◽

pp. 012023 ◽

Cited By ~ 1

Author(s):

AD Prismayanti ◽

A Damar ◽

NTM Pratiwi

Keyword(s):

Trophic State ◽

Inorganic Nitrogen ◽

Dissolved Inorganic Nitrogen

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Changes of the nutrient loads of the Odra River during the last century - their causes and consequences

Journal of Water and Land Development ◽

10.2478/v10025-009-0010-0 ◽

2008 ◽

Vol 12 (1) ◽

pp. 127-144 ◽

Cited By ~ 14

Author(s):

Horst Behrendt ◽

Dieter Opitz ◽

Agnieszka Kolanek ◽

Rafalina Korol ◽

Marzenna Strońska

Keyword(s):

Point Source ◽

Total Phosphorus ◽

Inorganic Nitrogen ◽

Nutrient Loads ◽

Dissolved Inorganic Nitrogen ◽

Total N ◽

Odra River ◽

Time Periods ◽

Total P ◽

Point Source Discharges

Changes of the nutrient loads of the Odra River during the last century - their causes and consequencesNutrient emissions by point and diffuse sources and their loads were estimated for the Odra catchment over the time period of the last 50 years by means of the model MONERIS. For nitrogen a change of the total emissions from 38 kt·a−1N in the mid of 1950s a maximum of 105 kt·a−1N in the early 1980s and a recent value of about 84 kt·a−1N were estimated for the total Odra Basin. The share of the point source discharges on the total N emissions varied between 24% (1955) and 35% (1995). The emissions from groundwater and tile drained areas represent the dominant pathway (37-56% of total N emissions) during all investigated time periods. Emissions from tile drained areas increased from the mid of 1950s to end of 1980s by a factor of 20 and reached in this period the same amount as emissions by groundwater. For phosphorus the emissions changed from 4 kt·a−1P in 1955 to 14 kt·a−1P in 1990 and a recent level of 7 kt·a−1P. Point source discharges caused between 36 to 66% of total P emissions and represent the dominant pathway for all investigated time periods. Erosion and discharges from paved urban areas and sewer systems was the dominant diffuse pathway of the total P emissions into the river system. The comparison of calculated and observed nutrient loads for the main monitoring stations along the Odra River shows that the average deviation is 12% for total phosphorus (1980-2000) and 15% for dissolved inorganic nitrogen (1960-2000). From the analysis it can be concluded that the present load of dissolved inorganic nitrogen (DIN) and total nitrogen (TN) of the Odra into the Baltic Sea is about 2.3 times higher than in the mid of 1960s. The maximum DIN load (1980s) was more than 3 times higher than in the 1960s. The change of the total phosphorus (TP) load is characterized by an increase from the 1955s to 1980 from 2 to 7 kt·a−1P (factor 2.6). Around 2000 the TP load was 4 kt·a−1which is only the double of the level of the 1955s.

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Prediction of Algal Chlorophyll-a and Water Clarity in Monsoon-Region Reservoir Using Machine Learning Approaches

Water ◽

10.3390/w12010030 ◽

2019 ◽

Vol 12 (1) ◽

pp. 30 ◽

Cited By ~ 6

Author(s):

Md Mamun ◽

Jung-Jae Kim ◽

Md Ashad Alam ◽

Kwang-Guk An

Keyword(s):

Chlorophyll A ◽

Trophic State ◽

Secchi Depth ◽

Water Clarity ◽

Coefficient Of Determination ◽

Annual Rainfall ◽

Support Vector ◽

Chl A ◽

Svm Model ◽

Ann Models

The prediction of algal chlorophyll-a and water clarity in lentic ecosystems is a hot issue due to rapid deteriorations of drinking water quality and eutrophication processes. Our key objectives of the study were to predict long-term algal chlorophyll-a and transparency (water clarity), measured as Secchi depth, in spatially heterogeneous and temporally dynamic reservoirs largely influenced by the Asian monsoon during 2000–2017 and then determine the reservoir trophic state using a multiple linear regression (MLR), support vector machine (SVM) and artificial neural network (ANN). We tested the models to analyze the spatial patterns of the riverine zone (Rz), transitional zone (Tz) and lacustrine zone (Lz) and temporal variations of premonsoon, monsoon and postmonsoon. Monthly physicochemical parameters and precipitation data (2000–2017) were used to build up the models of MLR, SVM and ANN and then were confirmed by cross-validation processes. The model of SVM showed better predictive performance than the models of MLR and ANN, in both before validation and after validation. Values of root mean square error (RMSE) and mean absolute error (MAE) were lower in the SVM model, compared to the models of MLR and ANN, indicating that the SVM model has better performance than the MLR and ANN models. The coefficient of determination was higher in the SVM model, compared to the MLR and ANN models. The mean and maximum total suspended solids (TSS), nutrients (total nitrogen (TN) and total phosphorus (TP)), water temperature (WT), conductivity and algal chlorophyll (CHL-a) were in higher concentrations in the riverine zone compared to transitional and lacustrine zone due to surface run-off from the watershed. During the premonsoon and postmonsoon, the average annual rainfall was 59.50 mm and 54.73 mm whereas it was 236.66 mm during the monsoon period. From 2013 to 2017, the trophic state of the reservoir on the basis of CHL-a and SD was from mesotrophic to oligotrophic. Analysis of the importance of input variables indicated that WT, TP, TSS, TN, NP ratios and the rainfall influenced the chlorophyll-a and transparency directly in the reservoir. These findings of the algal chlorophyll-a predictions and Secchi depth may provide key clues for better management strategy in the reservoir.

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Seasonal Occurrence of Cyanobacteria and First Detection of Microcystin-LR in Water Column of Foum-Gleita Reservoir, Mauritania

10.21203/rs.3.rs-1010774/v1 ◽

2021 ◽

Author(s):

Ahmed Sidi Sadegh ◽

Zeinebou Sidoumou ◽

Mamadou Dia ◽

Juan Luis Gómez Pinchetti ◽

Noureddine Bouaïcha

Keyword(s):

Surface Water ◽

Environmental Factors ◽

Water Column ◽

Microcystis Aeruginosa ◽

Total Phosphorus ◽

Inorganic Nitrogen ◽

Cyanobacterial Blooms ◽

World Health ◽

Seasonal Occurrence ◽

Dissolved Inorganic Nitrogen

Abstract This work was carried out to study the seasonal occurrence of cyanobacteria and their microcystin-LR in water column of Foum-Gleita reservoir (Mauritania). Limnological and biological factors were investigated at three depths (surface, -3, and -6 m) in this reservoir during a full year. Nutrients were analyzed by Spectrophotometry, phytoplankton was analyzed by Inverted Microscopy, microsystins were analyzed by High Performance Liquid Chromatography-tandem Mass Spectrometry and environmental factors relationships were analyzed by Pearson's correlation and Multiple Linear Regression. Physicochemical analyzes have shown that this reservoir is hypereutrophic with dissolved inorganic nitrogen and total phosphorus concentrations relatively high, varying from 1.39 to 6.53 and 0.21 to 0.57 mg/L, respectively. Annual surface water temperature was exceptionally high (27.8 ± 3.6°C), characterizing of a Sahelian climatic conditions. Phytoplankton analyzes have shown dominance of two toxic cyanobacteria species Microcystis aeruginosa and Dolichospermum flos-aquae during warm season (May-September). Microcystins analysis revealed presence of only most toxic variant, microcystin-LR. Microcystin-LR concentration in the surface water samples, during cyanobacterial blooms, was consistently high (5.638 µg/L), exceeding 5-times the World Health Organization drinking water limit (1 µg/L), however, it was much lower (0.83 µg / L) at depth (-6 m). Analysis of environmental factors relationships showed that the most influential factors on abundance of Microcystis aeruginosa and Dolichospermum flos-aquae and variability of microcystin-LR concentrations were total phosphorus, dissolved inorganic nitrogen, iron, temperature and pH. Finally, the study clearly demonstrated need for regular monitoring of cyanobacteria and cyanotoxins in the waters of studied reservoir.

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Water Quality Trends in Hamilton Harbour: 1987 to 1995

Water Quality Research Journal ◽

10.2166/wqrj.1996.027 ◽

1996 ◽

Vol 31 (3) ◽

pp. 473-484 ◽

Cited By ~ 9

Author(s):

Murray N. Charlton ◽

Robin Le Sage

Keyword(s):

Algal Blooms ◽

Action Plan ◽

Secchi Depth ◽

Water Clarity ◽

Nutrient Loads ◽

Hamilton Harbour ◽

Near Shore ◽

The Media ◽

Park Area ◽

Water Quality Trends

Abstract A series of water samples and Secchi depth measurements were conducted in Hamilton Harbour between 1987 and 1995. The data indicate little recent improvement in the harbour generally. Detection of real improvements may require high frequency sampling and a more extensive sample grid once a cause for improvement is in place. Some measures, such as chlorophyll and Secchi depth, approach RAP initial goals sometimes during recent years, but algal blooms still occur, which prevent attainment of satisfactory average conditions. The cause of aesthetic improvements in water clarity reported in the media was investigated with sampling along an inshore-offshore transect and intense Secchi measurements in the LaSalle Park area. The data are consistent with a transient clarifying effect of zebra mussels on structures near shore. The need to reduce nutrient loads as recommended in the Remedial Action Plan continues.

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Spatial and Temporal Water Quality Trends in Severn Sound, Georgian Bay, since the Introduction of Phosphorus Control Guidelines: Nutrients and Phytoplankton, 1973 to 1991

Water Quality Research Journal ◽

10.2166/wqrj.1995.044 ◽

1995 ◽

Vol 30 (4) ◽

pp. 565-592 ◽

Cited By ~ 1

Author(s):

A.F. Gemza

Keyword(s):

Total Phosphorus ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Soluble Reactive Phosphorus ◽

Euphotic Zone ◽

Water Clarity ◽

Sewage Treatment Plants ◽

Order Of Magnitude ◽

Phosphorus Levels

Abstract Severn Sound continues to exhibit signs of eutrophication despite initial identification of the problem in 1969 and the construction of several sewage treatment plants since then. In general, improvements in trophic state indicators have been marginal, suggesting that the sewage treatment plants have had limited success in controlling phosphorus concentrations. These discharges likely contributed to the increased total phosphorus levels and consequently the higher phytoplankton densities of the nearshore waters. Phytoplankton biovolumes were on average one order of magnitude higher than in the open waters of Lake Huron with mean summer biovolumes as high as 8.0 mm/L. Algal biovolumes were most dense in Penetang Bay, which experienced limited exchange with the main waters of the sound. No significant long-term trends were observed. Water clarity was declining significantly, however, at a rate of -0.60 to -0.78 m/year throughout the sound except in Sturgeon Bay. Total phosphorus levels were highly variable from year to year; however, concentrations from a 20-year perspective were declining in the open waters at a rate of 0.70 µg/L/year, but response was limited in nearshore areas. In Sturgeon Bay, mean annual euphotic zone total phosphorus as well as soluble reactive phosphorus levels declined by as much as 50% following the construction of a sewage treatment plant with tertiary treatment. Phytoplankton genera typical of eutrophic waters continued to dominate the algal assemblage but members indicative of mesotrophic conditions have become apparent in some areas of the sound.

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Characteristics of Non-Point Source N Export via Surface Runoff from Sloping Croplands in Northeast China

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.347-353.2302 ◽

2011 ◽

Vol 347-353 ◽

pp. 2302-2307 ◽

Cited By ~ 1

Author(s):

Hong Xiang Wang ◽

Yi Shi ◽

Jian Ma ◽

Cai Yan Lu ◽

Xin Chen

Keyword(s):

Point Source ◽

Surface Runoff ◽

Rainfall Intensity ◽

Inorganic Nitrogen ◽

Rainfall Amount ◽

Organic N ◽

Dissolved Inorganic Nitrogen ◽

Slope Gradient ◽

N Loss ◽

Total N

A field experiment was conducted to study the characteristics of non-point source nitrogen (N) in the surface runoff from sloping croplands and the influences of rainfall and cropland slope gradient. The results showed that dissolved total N (DTN) was the major form of N in the runoff, and the proportion occupied by dissolved inorganic nitrogen (DIN) ranged from 45% to 85%. The level of NH4+-N was generally higher than the level of NO3--N, and averaged at 2.50 mg·L-1and 1.07 mg·L-1respectively. DIN was positively correlated with DTN (R2=0.962). Dissolved organic N (DON) presented a moderate seasonal change and averaged at 1.40 mg·L-1. Rainfall amount and rainfall intensity significantly affected the components of DTN in the runoff. With the increase of rainfall amount and rainfall intensity, the concentrations of DTN, NH4+-N and NO3--N presented a decreased trend, while the concentration of DON showed an increased trend. N loss went up with an increase in the gradient of sloping cropland, and was less when the duration was longer from the time of N fertilization.fertilization.

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