Impacts of phosphorus loads on the water quality and the proliferation of harmful cyanobacteria in Foum-Gleita Reservoir (Mauritania)

2021 ◽  
Vol 57 ◽  
pp. 1
Author(s):  
Ahmed Sidi Sadegh ◽  
Zeinebou Sidoumou ◽  
Mamadou Dia ◽  
Juan Luis Gomez Pinchetti ◽  
Noureddine Bouaïcha
Keyword(s):  
Water Quality ◽  
High Performance ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
Pearson’S Correlation ◽  
Biological Variables ◽  
Nitrogen Inputs ◽  
Harmful Cyanobacteria ◽  
Nitrogen Concentrations ◽  
Pearson's Correlation

Excess phosphorus and nitrogen inputs into freshwater ecosystems is one of the main causes of expansion of harmful cyanobacterial blooms worldwide. This work was conducted to study the impacts of phosphorus leaching from the exploitation of phosphate mines present in the watershed of Foum-Gleita Reservoir (Mauritania) on the water quality and its major contribution to the proliferation of harmful cyanobacteria throughout the year. The physicochemical parameters, the occurrence and abundance of phytoplankton (including cyanobacteria), and the microcystins concentration were monitored monthly from September 2017 to August 2018. The relationships between limnological and biological variables were explored by using Pearson's correlation and forward stepwise multiple linear regression (MLR) analysis. Microcystins were detected by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Our results showed that this reservoir can be classified as hypereutrophic throughout the year and that Microcystis aeruginosa (M. aeruginosa) and Dolichospermum flos-aquae (D. flos-aquae) were dominant species during the rainy season (July-September), and only the congener microcystin-LR (MC-LR) was detected with a peak at 3.55 µg L−1. Pearson's correlation and MLR analysis showed that water temperature pH, phosphorus, nitrogen, and iron concentrations were the most important variables accounting for M. aeruginosa and D. flos-aquae abundance and MC-LR concentration. Our study provides new insight into the effects of moderate nitrogen concentrations on phytoplankton community composition with dominance of the cyanobacteria phylum in phosphorus-rich freshwater ecosystems.

scholarly journals The Occurrence of Potential Harmful Cyanobacteria and Cyanotoxins in the Obrzyca River (Poland), a Source of Drinking Water

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 284 ◽  
Author(s):  
Wanda Czyżewska ◽  
Marlena Piontek ◽  
Katarzyna Łuszczyńska
Keyword(s):  
Water Quality ◽  
Drinking Water ◽  
Dominant Species ◽  
Cyanobacterial Blooms ◽  
Effective Control ◽  
Dugesia Tigrina ◽  
Chemical Indicators ◽  
Drinking Water Resources ◽  
Harmful Cyanobacteria ◽  
Contaminate Drinking Water

Harmful cyanobacteria and their cyanotoxins may contaminate drinking water resources and their effective control remains challenging. The present study reports on cyanobacterial blooms and associated cyanotoxins in the Obrzyca River, a source of drinking water in Poland. The river was examined from July to October 2019 and concentrations of microcystins, anatoxin-a, and cylindrospermopsin were monitored. The toxicity of water samples was also tested using an ecotoxicological assay. All studied cyanotoxins were detected with microcystins revealing the highest levels. Maximal microcystin concentrations (3.97 μg/L) were determined in September at Uście point, exceeding the provisional guideline. Extracts from Uście point, where the dominant species were Dolichospermum flos-aquae (August), Microcystis aeruginosa (September), and Planktothrix agardhii (October), were toxic for Dugesia tigrina Girard. Microcystin concentrations (MC-LR and MC-RR) were positively correlated with cyanobacteria biovolume. Analysis of the chemical indicators of water quality has shown relationships between them and microcystins as well as cyanobacteria abundance.

scholarly journals The influence of nitrogen and growth phase on the toxicity of the cyanobacterial strain Microcystis PCC 7806

2019 ◽  
pp. 89-100
Author(s):  
Petar Davidovic ◽  
Dajana Blagojevic ◽  
Olivera Babic ◽  
Jelica Simeunovic
Keyword(s):  
Growth Phase ◽  
Larval Mortality ◽  
Artemia Salina ◽  
Freshwater Ecosystems ◽  
Cyanobacterial Blooms ◽  
High Dose ◽  
Toxic Metabolite ◽  
Cyanobacterial Strain ◽  
Test Organisms ◽  
Nitrogen Concentrations

The worldwide occurrence of toxic cyanobacterial blooms and their numerous harmful effects have instigated extensive research into the environmental conditions promoting such events. Among the environmental factors which have been suggested to influence the increase in cyanobacterial proliferation, nutrient levels have been identified as one of the most prominent, affecting the growth and toxic metabolite production of cyano?bacteria in freshwater ecosystems. In the present study, toxicity of the cyanobacterial strain Microcystis PCC 7806 was evaluated after growth in media with three different nitrogen concentrations. The toxicity of intracellular extracts was analyzed during different growth phases (after 7, 21, and 35 days of cultivation) by observing mortality rates in the Artemia salina bioassay after 24h and 48h of exposure. The results have not shown significantly higher mortality levels between the test organisms exposed to extracts obtained from the cultures grown in the presence of higher nitrogen content (1.5 g/l and 0.8 g/l) and those grown in a nitrogen-free medium. A dose dependent effect, however, can be observed in most cases, with the most substantial changes observed in the high-dose groups. Also, the toxic effects and larval mortality increased during the exposure, suggesting the time-dependent toxicity. Extracts obtained after longer periods of cultivation (21 and 35 days) had stronger effects on the test organisms, which indicates that the toxicity of the tested cyanobacterial strain depends on the specific growth phase.

scholarly journals Harmful Cyanobacteria in Three Oregon Lakes: Comments on Hall et al. Beyond Water Quality Advisories and Total Maximum Daily Loads (TMDLs). Water 2019, 11, 1125

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2482
Author(s):  
Joseph Eilers
Keyword(s):  
Water Quality ◽  
Current System ◽  
Timber Harvest ◽  
The State ◽  
Cyanobacterial Blooms ◽  
Septic Systems ◽  
Total Maximum Daily Loads ◽  
Harmful Cyanobacteria ◽  
Maximum Daily Loads ◽  
Total Maximum

The article “An Ecological Function Approach to Managing Harmful Cyanobacteria in Three Oregon Lakes: Beyond Water Quality Advisories and Total Maximum Daily Loads (TMDLs), Water 11:1125” by Hall et al. critiques the current approach used by the state of Oregon with regard to managing cyanobacterial blooms and offers the proper functioning condition (PVC) as a superior method of managing cyanobacterial blooms in lakes derived from nonpoint sources of pollution. They evaluated three lakes in Oregon as examples of how this approach could be applied to support water quality improvement. Two of the three lakes, Lemolo and Diamond, experienced cyanobacterial blooms, not as a function of nonpoint source loadings from the watershed, but rather because of internal nutrient cycling associated with high fish biomass. The third lake, Tenmile Lakes, in additional to having a greatly altered fish community, also experiences cyanobacterial blooms (CyanoHABs) issues because of timber harvest on steep slopes, loss of wetlands, altered watershed hydrology and nutrient input from septic systems. The authors’ attempts to use satellite images and PVC methodology on the stream networks is incomplete with respect to Tenmile Lakes and is totally misdirected regarding Lemolo and Diamond Lakes. Although I don’t support the current system employed by the state of Oregon to manage lakes experiencing CyanoHABs issues, the proposed approach offered by staff with the U.S. Environmental Protection Agency will yield little water quality benefit for the lakes in question.

scholarly journals The Aquatic Insect Communities of Universiti Malaysia Sabah (UMS), Sabah, Malaysia

2015 ◽  
Vol 3 (1) ◽  
pp. 1-5
Author(s):  
Arman Hadi Mohmad ◽  
Mohd Shafiq Izzat Shafie ◽  
Andrew Wong Bak Hui ◽  
Sahana Harun
Keyword(s):  
Water Quality ◽  
Dissolved Oxygen ◽  
Diversity Index ◽  
Aquatic Insect ◽  
Quality Parameters ◽  
Water Quality Parameters ◽  
Insect Communities ◽  
Pearson’S Correlation ◽  
Insect Abundance ◽  
Pearson's Correlation

A s tudy was conducted to investigate the aquatic insect communities in Universiti Malaysia Sabah (UMS), Sabah, Malaysia. Two sampling sites were selected: lakes at School of Science and Technology (SST), and another near College E (CE) (student accommodation). Each lake consisted of four sampling stations. Aquatic insects were sampled using dip net from November 2013 to January 2014. Four water quality parameters were measured at each station. Shannon-Weiner’s diversity index and biotic indices (BMWP) were used in this study. Student’s t-test was used for testing the significant difference of water quality parameters, Shannon-Weiner’s diversity index and BMWP between these lakes. Pearson’s correlation was used to investigate relationships between aquatic insect assemblage and water quality parameters. A total of 1987 individuals composed of five orders that representing eleven families were recorded in this study. Baetidae (56.67%) was the dominant family in UMS, where Diptera order had least abundant with only 0.4% of overall sample. Aquatic insect abundance were significantly higher (P<0.05) in CE Lake. Bray-Curtis Similarity index showed 53.75% similarity between these two lakes. Pearson’s correlation showed that aquatic insect abundance and richness had significant relationships with water temperature, dissolved oxygen, salinity and pH (P<0.05 or 0.01), except for salinity with taxa richness. Based on Malaysia’s INWQS, water quality parameters of these two lakes were categorized as Class I, but with dissolved oxygen the CE and SST lakes were classified as Class IIA and III respectively. The BMWP index showed similar results as dissolved oxygen, where SST Lake (score=40) had poor water quality.

scholarly journals Deep learning-based segmentation of the lung in MR-images acquired by a stack-of-spirals trajectory at ultra-short echo-times

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Andreas M. Weng ◽  
Julius F. Heidenreich ◽  
Corona Metz ◽  
Simon Veldhoen ◽  
Thorsten A. Bley ◽  
...  
Keyword(s):  
Image Segmentation ◽  
Deep Learning ◽  
Accurate Estimation ◽  
Dice Similarity Coefficient ◽  
Manual Segmentation ◽  
Pearson’S Correlation ◽  
Lung Volumes ◽  
Lung Segmentation ◽  
Pearson's Correlation ◽  
Lung Mri

Abstract Background Functional lung MRI techniques are usually associated with time-consuming post-processing, where manual lung segmentation represents the most cumbersome part. The aim of this study was to investigate whether deep learning-based segmentation of lung images which were scanned by a fast UTE sequence exploiting the stack-of-spirals trajectory can provide sufficiently good accuracy for the calculation of functional parameters. Methods In this study, lung images were acquired in 20 patients suffering from cystic fibrosis (CF) and 33 healthy volunteers, by a fast UTE sequence with a stack-of-spirals trajectory and a minimum echo-time of 0.05 ms. A convolutional neural network was then trained for semantic lung segmentation using 17,713 2D coronal slices, each paired with a label obtained from manual segmentation. Subsequently, the network was applied to 4920 independent 2D test images and results were compared to a manual segmentation using the Sørensen–Dice similarity coefficient (DSC) and the Hausdorff distance (HD). Obtained lung volumes and fractional ventilation values calculated from both segmentations were compared using Pearson’s correlation coefficient and Bland Altman analysis. To investigate generalizability to patients outside the CF collective, in particular to those exhibiting larger consolidations inside the lung, the network was additionally applied to UTE images from four patients with pneumonia and one with lung cancer. Results The overall DSC for lung tissue was 0.967 ± 0.076 (mean ± standard deviation) and HD was 4.1 ± 4.4 mm. Lung volumes derived from manual and deep learning based segmentations as well as values for fractional ventilation exhibited a high overall correlation (Pearson’s correlation coefficent = 0.99 and 1.00). For the additional cohort with unseen pathologies / consolidations, mean DSC was 0.930 ± 0.083, HD = 12.9 ± 16.2 mm and the mean difference in lung volume was 0.032 ± 0.048 L. Conclusions Deep learning-based image segmentation in stack-of-spirals based lung MRI allows for accurate estimation of lung volumes and fractional ventilation values and promises to replace the time-consuming step of manual image segmentation in the future.

scholarly journals Case Study of Anaerobic Digestion Process Stability Detected by Dissolved Hydrogen Concentration

Processes ◽  
2021 ◽  
Vol 9 (1) ◽  
pp. 106
Author(s):  
Daniela Platošová ◽  
Jiří Rusín ◽  
Jan Platoš ◽  
Kateřina Smutná ◽  
Roman Buryjan
Keyword(s):  
Anaerobic Digestion ◽  
Correlation Coefficient ◽  
Hydrogen Concentration ◽  
Pearson’S Correlation ◽  
Pearson’S Correlation Coefficient ◽  
Digestion Process ◽  
Short Service Life ◽  
Pearson's Correlation ◽  
Dissolved Hydrogen ◽  
Pearson's Correlation Coefficient

The paper presents the results of a laboratory experiment of mesophilic single-stage anaerobic digestion performed to verify the possibility of early detection of process instability and reactor overload by evaluating the course of dissolved hydrogen concentration of the main intermediate. The digestion process was run in a Terrafors IS rotary drum bioreactor for 230 days. The substrate dosed on weekdays was food leftovers from the university canteen. At an average temperature of 37 °C, an organic loading of volatiles of 0.858 kg m−3 day−1 and a theoretical retention time of 259 days, biogas production of 0.617 Nm3 kg VS−1 was achieved with a CH4 content of 51.7 vol. %. The values of the established FOS/TAC stability indicator ranged from 0.26 to 11.4. The highest value was reached when the reactor was overloaded. The dissolved hydrogen concentration measured by the amperometric microsensor ranged from 0.039–0.425 mg dm−3. Data were statistically processed using Pearson’s correlation coefficient. The correlation of the hydrogen concentration with other parameters such as the concentration of organic acids was evaluated. The value of Pearson’s correlation coefficient was 0.331 and corresponded to a p-value of 0. The results confirmed a very low limit of the hydrogen concentration at which the microbial culture, especially methanogens, was already overloaded. The amperometric microsensor proved to be rather unsuitable for operational applications due to insufficient sensitivity and short service life. The newly designed ratio of dissolved hydrogen concentration to neutralizing capacity was tested but did not work significantly better than the established FOS/TAC stability indicator.

scholarly journals Potential for Mycorrhizae-Assisted Phytoremediation of Phosphorus for Improved Water Quality

2020 ◽  
Vol 18 (1) ◽  
pp. 7
Author(s):  
Jessica A. Rubin ◽  
Josef H. Görres
Keyword(s):  
Water Quality ◽  
Animal Health ◽  
Phosphorus Uptake ◽  
Agricultural Practices ◽  
Fold Increase ◽  
Landscape Patterns ◽  
Cyanobacterial Blooms ◽  
Terrestrial Plants ◽  
Source Reduction ◽  
Water Ecosystems

During this 6th Great Extinction, freshwater quality is imperiled by upland terrestrial practices. Phosphorus, a macronutrient critical for life, can be a concerning contaminant when excessively present in waterways due to its stimulation of algal and cyanobacterial blooms, with consequences for ecosystem functioning, water use, and human and animal health. Landscape patterns from residential, industrial and agricultural practices release phosphorus at alarming rates and concentrations threaten watershed communities. In an effort to reconcile the anthropogenic effects of phosphorus pollution, several strategies are available to land managers. These include source reduction, contamination event prevention and interception. A total of 80% of terrestrial plants host mycorrhizae which facilitate increased phosphorus uptake and thus removal from soil and water. This symbiotic relationship between fungi and plants facilitates a several-fold increase in phosphorus uptake. It is surprising how little this relationship has been encouraged to mitigate phosphorus for water quality improvement. This paper explores how facilitating this symbiosis in different landscape and land-use contexts can help reduce the application of fertility amendments, prevent non-point source leaching and erosion, and intercept remineralized phosphorus before it enters surface water ecosystems. This literature survey offers promising insights into how mycorrhizae can aid ecological restoration to reconcile humans’ damage to Earth’s freshwater. We also identify areas where research is needed.

scholarly journals Geochemical and biological controls on the ecological relevance of total, dissolved, and colloidal forms of trace elements in large boreal rivers: review and case studies

2020 ◽  
Vol 28 (2) ◽  
pp. 138-163
Author(s):  
C.W. Cuss ◽  
C.N. Glover ◽  
M.B. Javed ◽  
A. Nagel ◽  
W. Shotyk
Keyword(s):  
Water Quality ◽  
Trace Elements ◽  
Case Studies ◽  
Quality Criteria ◽  
Water Levels ◽  
Water Quality Criteria ◽  
Aquatic Life ◽  
Athabasca River ◽  
Biological Variables ◽  
Boreal Rivers

The concentrations of trace elements (TEs) in large boreal rivers can fluctuate markedly due to changing water levels and flow rates associated with spring melt and variable contributions from tributaries and groundwaters, themselves having different compositions. These fluctuating and frequently high concentrations create regulatory challenges for protecting aquatic life. For example, water quality criteria do not account for changes in flow regimes that can result in TE levels that may exceed regulatory limits, and neither do they account for the markedly different lability and bioaccessibility of suspended solids. This review addresses the geochemical and biological processes that govern the lability and bioaccessibility of TEs in boreal rivers, with an emphasis on the challenges posed by the colloidal behaviour of many TEs, and their relationship to the dissolved fraction (i.e., <0.45 μm in size). After reviewing the processes and dynamics that give rise to the forms and behaviour of TEs in large boreal rivers, their relevance for aquatic organisms and the associated relationships between size and lability and bioaccessibility are discussed. The importance of biological variables and different forms of TEs for limiting lability and bioaccessibility are also addressed. Two case studies emphasize seasonal fluctuations and accompanying changes in the distribution of TE amongst different size fractions and associated colloidal species in large boreal rivers: the Northern Dvina and one of its tributaries, the Pinega River, both in Russia, and the Athabasca River in Alberta, Canada. Water quality in the Athabasca River is briefly discussed with respect to Canadian guidelines.

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