ARTICLE | doi:10.20944/preprints201912.0277.v2
Subject: Biology, Ecology Keywords: coastal lagoon; phytoplankton; eutrophication; nanoplanktonic algae
Online: 20 July 2020 (04:22:11 CEST)
The Mar Menor is a Spanish coastal lagoon of great ecological and economic interest. The agricultural and tourist activities developed in the surroundings of the lagoon, together with the modifications in its channels of connection with the Mediterranean Sea, have notably affected the quality of its waters, which is altering the natural balance of the ecosystem. In this work, an analysis of the density of phytoplankton present in the lagoon between the months of May to December 2017 has been carried out. There, it has been a notable increase in the density of organisms in post-summer samplings, following the recording of higher temperatures, and the presence of Chlorophyceae, Cyanophyceae, Chrysophyceae and nanoplanktonic Cryptophyceae stands out. The data collected indicate a significant increase in the eutrophication process of the lagoon that requires the development of management plans to reduce agricultural discharges and promote the recovery of the lagoon and its native species.
ARTICLE | doi:10.20944/preprints202110.0340.v1
Subject: Biology, Agricultural Sciences & Agronomy Keywords: eutrophication; phosphorus sorption; soil Olsen P; soil organic matter
Online: 25 October 2021 (10:40:00 CEST)
The Mediterranean region offers good weather conditions for outdoor pig production (OPP), which is considered more environmentally friendly than intensive indoor production. However, the continuous input of food and pigs' excreta increases the soil organic matter (SOM) and phosphorus (P), increasing the risk of waterbodies eutrophication. This work aimed at evaluating in OPP areas soil P dynamics and the role of SOM on P sorption and P release. The experiment was done for two years, at an area of 2.8 ha with an animal charge of 9 adults ha-1. Georeferenced soil samples were taken at 0.20 m depth, and a soil P sorption experiment was carried out. At the end of the experiment, for the background value, the levels of SOM increased between 85–376%, and Olsen P values ranged between -82–884%. SOM levels above 2% caused a decrease in the binding energy of P sorption according to the linear model b=-15.541SOM+115.20 (p <0.01) as well as a decrease of the soil P sorption capacity Qmax=-41.272SOM+298.37 (p <0.01). To avoid the accumulation of SOM and P preventing hotspots for waterbodies eutrophication, an adequate animal charge together with soil cultivation for pig grazing can be a cost-effective practice.
ARTICLE | doi:10.20944/preprints201909.0054.v1
Subject: Engineering, Other Keywords: Shanghai; water quality; eutrophication; conventional water treatment; secondary water pollution
Online: 5 September 2019 (07:47:59 CEST)
Shanghai is experiencing water supply problems caused by heavy pollution of its raw water supply, deficiencies in its treatment processes and water quality deteoriation in the distribution system. However, little attention has been paid these problems of water quality in raw water, water treatment and household drinking water. Based on water quality data we show that the raw water sources of the Huangpu River and the Changjiang (Yangtze River) estuary are polluted by microbes (TBC), eutrophication (TP, TN and NH3-N), heavy metals (Fe, Mn and Hg) and organic contamination (chemical oxygen demand [COD], detergent and volatile phenols [VP]). The average concentrations of these contaminants in the Huangpu River are almost double that of the Changjiang estuary forcing a rapid shift to the Changjiang estuary for raw water. In spite of filtering and treatment, TN, NH3-N, Fe, COD and chlorine maxima of the treated water and drinking water still exceed the Chinese National Standard (GB5749). We determine that the relevant threats from water source to household water in Shanghai are: 1) eutrophication arising from highly concentrated TN, TP, COD and algal density in the raw water; 2) increasing salinity in the river estuary, especially at the Qingcaosha Reservoir (currently the major freshwater source for Shanghai); 3) more than 50% of organic constituents and by-products remain in treated water; 4) bacteria and turbidity increase in the course of water delivery to users. The analysis presents an holistic assessment of the water quality threats to metropolitan Shanghai in relation to the city’s rapid development.
ARTICLE | doi:10.20944/preprints201810.0715.v1
Subject: Earth Sciences, Oceanography Keywords: Western South Atlantic continental margin; benthic Foraminifera; fresh water; nutrients; eutrophication; anoxic
Online: 30 October 2018 (08:51:08 CET)
The present work focuses on fresh water signatures at the sediment-water interface (1 cm) using foraminiferal species in both austral winter and summer in eleven longitudinal transects on the Western South Atlantic continental margin between 27° and 37° S, at water depths of 11.7 to 250 m. Here we show that depth, salinity, temperature, oxygen, grain size (mud and sand percentage), suspended matter, organic matter, SiO4, NO2, and NO3 in this order of importance are responsible for the distribution of foraminiferal species and thecamoebians. The presence of these microfossils indicate freshwater influx in four sectors over the continental shelf: Itajaí-Açu River, Laguna estuarine system, Patos Lagoon and RdlP (Rio de la Plata) will be explored further in detail. Our findings on freshwater signature on the continental shelf sediments through benthic species indicator are comparable to other continental systems worldwide, and a paleo record study would be useful for three South American countries (Brazil, Argentina and Uruguay). A freshwater signature in the continental shelf indicates deposition sites probably linked to anthropogenic impact since most of the pollutants and contaminants are dumped into water bodies that eventually reach and accumulate in the ocean. Therefore, the freshwater-related species on the continental shelf reflects exactly where the depositional sediment sites are, and where anthropogenic impacts accumulate. Foraminiferal microhabitat occupation within these zones is discussed in detail. And we conclude that together with the fauna, the abiotic parameters play an important role in determining the occurrence and degree of marine eutrophication induced by the input of polluted river waters, also showing possible anoxic environments on the shelf.
ARTICLE | doi:10.20944/preprints201810.0035.v1
Subject: Engineering, Civil Engineering Keywords: water quality; model calibration; estuary; eutrophication; CE-QUAL-W2; phytoplankton, algal growth kinetics
Online: 2 October 2018 (16:56:46 CEST)
The two-dimensional, laterally-averaged mechanistic eutrophication model CE-QUAL-W2 version 3.72 was used to predict chlorophyll-a concentrations across two different time periods in the Neuse River Estuary, North Carolina. Chlorophyll calibration was performed for two time periods simultaneously by performing by a full-factorial experiment that tested seven algal kinetic growth parameters over three levels for a single algal group. A cluster of up to six computers each running between two and ten instances of the program was used to complete and manage the data for 2187 runs for each time period. A set of six criteria were used to determine which runs performed acceptably, yielding a group of 27 cases that met all of the criteria. Calibration performance of the set of cases outperformed a previously calibrated model using three algal groups that met only four of the six selection criteria. Calibration performed this way allowed for a more rational specification of model calibration performance and provided uncertainty estimates of model predictions, albeit at the cost of a considerable increase in computational requirements that necessitated the use of a computer cluster.
ARTICLE | doi:10.20944/preprints201711.0075.v1
Subject: Earth Sciences, Environmental Sciences Keywords: water quality; eutrophication; tropic state index; Landsat-8, RapidEye, tropical inland water bodies, Brazil
Online: 13 November 2017 (03:33:35 CET)
We aimed at analyzing Chlorophyll-a and CDOM dynamics from field measurements and at assessing the potential of multispectral satellite data for retrieving water-quality parameters in three small surface reservoirs in the Brazilian semiarid region. More specifically, this work comprises i) analysis of Chl-a and trophic dynamics; ii) characterization of CDOM; iii) estimation of Chl-a and CDOM from OLI/Landsat-8 and RapidEye imagery. The monitoring lasted 20 months within a multi-year drought, which contributed to water-quality deterioration. Chl-a and trophic state analysis showed a highly eutrophic status for the perennial reservoir during the entire study period, while the non-perennial reservoirs ranged from oligotrophic to eutrophic, with changes associated with the first events of the rainy season. CDOM characterization suggests that the perennial reservoir is mostly influenced by autochthonous sources, while allochthonous sources dominate the non-perennial ones. Spectral-group classification assigned the perennial as CDOM-moderate and highly eutrophic reservoir, whereas the non-perennial ones were assigned as CDOM-rich and oligotrophic-dystrophic reservoirs. The remote sensing initiative was partially successful: the Chl-a was best modelled using RapidEye for the perennial; whereas CDOM performed best with Landsat-8 for non-perennial reservoirs. This investigation showed high potential for retrieving water quality parameters in dry areas with small reservoirs.
ARTICLE | doi:10.20944/preprints202205.0387.v1
Subject: Earth Sciences, Environmental Sciences Keywords: hyperspectral imager; UAV remote sensing; water quality monitoring; space-ground data; buoy spectrometer; water eutrophication; absorption characteristics
Online: 30 May 2022 (05:59:36 CEST)
The effective integration of aerial remote sensing data and ground multi-source data has always been one of the difficulties of quantitative remote sensing. A new monitoring mode is designed which installs the hyperspectral imager on the UAV and places a buoy spectrometer on the river. Water samples are collected simultaneously to obtain in situ assay data of total phosphorus, total nitrogen, COD, turbidity and chlorophyll during data collection. The cross correlogram spectral matching (CCSM) algorithm is used to match the data of the buoy spectrometer with the UAV spectral data to reduce the UAV data noise significantly. An absorption characteristics recognition algorithm (ACR) is designed to realize a new method for comparing UAV data with laboratory data. This method takes into account the spectral characteristics and the correlation characteristics of test data synchronously. It is concluded that the most accurate water quality parameters can be calculated by using the regression method under five scales after the regression tests of multiple linear regression method (MLR), support vector machine method (SVM) and neural network (NN) method. This new working mode of integrating spectral imager data with point spectrometer data will become a trend in water quality monitoring.
ARTICLE | doi:10.20944/preprints202110.0126.v1
Subject: Earth Sciences, Environmental Sciences Keywords: Cumulative effects; fine sediment; particulate phosphorus; sediment geochemistry; gravel-bed rivers; forest disturbance; wildfire; eutrophication; climate change
Online: 8 October 2021 (08:07:28 CEST)
Cumulative effects of landscape disturbance in forested source water regions can alter the storage of fine sediment and associated phosphorus in riverbeds, shift nutrient dynamics and degrade water quality. Here, we examine longitudinal changes in major element chemistry and particulate phosphorus (PP) fractions of river-bed sediment in an oligotrophic river during environmentally sensitive low flow conditions. Study sites along 50 km of the Crowsnest River were located below tributary inflows from sub-watersheds and represent a gradient of increasing cumulative sedi-ment pressures across a range of land disturbance types (harvesting, wildfire, and municipal wastewater discharges). Major elements (Si2O, Al2O3, Fe2O3, MnO, CaO, MgO, Na2O, K2O, Ti2O, V2O5, P2O5), loss on ignition (LOI), PP fractions (NH4CI-RP, BD-RP, NaOH-RP, HCI-RP and NaOH(85)-RP) and absolute particle size were evaluated for sediments collected in 2016 and 2017. While total PP concentrations were similar across all sites, bioavailable PP fractions (BD-RP, NaOH-RP) increased downstream with increased concentrations of Al2O3 and MnO and levels of landscape disturbance. This study highlights the longitudinal water quality impacts of increasing landscape disturbance on bioavailable PP in fine riverbed sediments and shows how the convergence of climate (wildfire) and anthropogenic (sewage effluent, harvesting, agriculture) drivers can produce legacy effects on nutrients.
ARTICLE | doi:10.20944/preprints201705.0096.v1
Subject: Biology, Ecology Keywords: fish assemblages; community dynamics; alternate stable states; eutrophication; submerged aquatic vegetation; nutrient load reduction; point-source pollution
Online: 11 May 2017 (07:54:59 CEST)
After a local pollution control plant significantly reduced phosphorus loading into a phytoplankton-dominated tributary of the Potomac River in the early 1980’s, water quality and biological communities were monitored bi-weekly from April-September. After a 10-year time-lag, submerged aquatic vegetation (SAV), once abundant in this freshwater tidal embayment, returned to the area in 1993. After additional reductions in nitrogen load starting in 2000, the system completely switched to a SAV-dominated state in 2005. Fish abundance didn’t change during these distinct phase changes, but the fish community structure did. Increases in SAV provided refuge and additional spawning substrate for species with adhesive eggs such as Banded Killifish (Fundulus diaphanus), which is now the most abundant species in the embayment. Other changes seen were a decrease in the relative contribution of open water dwelling species such as White Perch (Morone americana), and an increase of visual predators such as Largemouth Bass (Micropterus salmoides). The 30-year record of data from this Potomac River tributary has revealed many important long-term trends that validate the effectiveness of initiatives to improve water treatment, and will aid in the continued management of the watershed and point source inputs.
ARTICLE | doi:10.20944/preprints202008.0282.v1
Subject: Chemistry, Analytical Chemistry Keywords: cyanobacteria; cyanopeptides; eutrophication; harmful bloom; liquid chromatography tandem mass spectrometry; Global Natural Product Social networking (GNPS); Dereplication strategy.
Online: 12 August 2020 (10:15:46 CEST)
Man-made shallow fishponds in the Czech Republic have been facing a high eutrophication since 1950s. Anthropogenic eutrophication and feeding of fish have strongly affected the physico-chemical properties of water and its aquatic community composition leading to harmful algal bloom formation. In our current study, we have characterised the phytoplankton community across three hypertrophic ponds to assess the phytoplankton dynamics during the vegetation season. We microscopically identified and quantified 29 cyanobacterial taxa comprised of non-toxigenic and toxigenic species. Further, a detailed cyanopeptides (CNPs) profiling was performed using molecular networking analysis of liquid chromatography tandem mass spectrometry (LC–MS/MS) data coupled with dereplication strategy. This MS networking approach coupled with dereplication on online global natural product social networking (GNPS) web platform led us to putatively identify forty CNPs: fourteen anabaenopeptins, ten microcystins, five cyanopeptolins, six microginins, two cyanobactins, a dipeptide radiosumin, a cyclooctapeptide planktocyclin and epidolastatin12. We have applied the binary logistic regression to estimate the CNPs producer by correlating the GNPS data with the species abundance. Usage of The combination of molecular networking and dereplication on online global natural product social networking (GNPS) web platform has proved as a valuable approach for rapid and simultaneous detection of high number of peptides, and rapidly assessing the risk for harmful bloom.
ARTICLE | doi:10.20944/preprints202105.0721.v3
Subject: Earth Sciences, Environmental Sciences Keywords: eutrophication; water management; hypolimnetic warming; boundary mixing; mixing events; internal waves; long-term series; Valle de Bravo; biogeochemistry; nutrient flux
Online: 28 October 2021 (16:12:32 CEST)
Physical processes play important roles in controlling eutrophication and oligotrophication. In stratified lakes, internal waves can cause vertical transport of heat and nutrients without breaking the stratification, through boundary mixing events. Such is the case in tropical Valle de Bravo (VB) lake, where strong diurnal winds drive internal waves, boundary mixing and hypolimnetic warming during stratification periods. We monitored VB during 18 years (2001-2018) when important water-level fluctuations (WLF) occurred, affecting mixing and nutrient flux. Mean hypolimnetic temperature increase (0.06–1.04°C month-1) occurred in all the stratifications monitored. We analyzed temperature distributions and modeled the hypolimnion heat budget to assess vertical mixing between layers (26,618–140,526 m-3h-1), vertical diffusivity coefficient KZ (6.2x10-7–3.3x10-6 m2s-1) and vertical nutrient entrainment to epilimnion on monthly scale. Stability also varied as a function of WLF. Nutrient flux to the epilimnion ranged 0.36–5.99 mg m-2d-1 for soluble reactive phosphorus (SRP) and 5.8–97.1 mg m-2d-1 for dissolved inorganic nitrogen (DIN). During low water-level years, vertical nutrient fluxes increase and can account for up to >40% of the total external nutrients load to the lake. Vertical mixing changes related to WLF affect nutrient recycling, their flux to sediments, ecosystemic metabolic balance and planktonic composition of VB.
REVIEW | doi:10.20944/preprints201703.0148.v1
Subject: Life Sciences, Other Keywords: microcystin; saxitoxin; cylindrospermopsin; anatoxin-a; anatoxin-a(S); cyanobacteria; organic anion transporting polypeptide; phosphatase inhibitor; acetylcholinesterase; neurotoxicity; water quality; eutrophication; drinking water
Online: 20 March 2017 (06:17:48 CET)
Cyanobacteria are ubiquitous phototrophic bacteria that inhabit diverse environments across the planet. They dominate many eutrophic lakes impacted by excess nitrogen (N) and phosphorus (P) forming dense accumulations of biomass known as cyanobacterial harmful algal blooms or cyanoHABs. Their dominance in eutrophic lakes is attributed to a variety of unique adaptations including N and P concentrating mechanisms, N fixation, colony formation that inhibits predation, vertical movement via gas vesicles, and the production of toxic or otherwise bioactive molecules. While some of these molecules have been explored for their medicinal benefits, others are potent toxins harmful to humans, animals, and other wildlife known as cyanotoxins. In humans these cyanotoxins affect various tissues, including the liver, central and peripheral nervous system, kidneys, and reproductive organs among others. They induce acute effects at low doses in the parts-per-billion range and some are tumor promoters linked to chronic diseases such as liver and colorectal cancer. The occurrence of cyanoHABs and cyanotoxins in lakes presents challenges for maintaining safe recreational aquatic environments and the production of potable drinking water. CyanoHABs are a growing problem in the North American (Laurentian) Great Lakes basin. This review summarizes information on the occurrence of cyanoHABs in the Great Lakes, toxicological effects of cyanotoxins, and appropriate numerical limits on cyanotoxins in finished drinking water.