Occurrence of microcystins in water,sediment,and aquatic animals in Dau Tieng Reservoir,Vietnam

This study investigates the variations of microcystins(MCs)in water,cyanobacterial blooms,sediment,and aquatic organisms collected from the Dau Tieng Reservoir(DTR).Vietnam.Highperformance liquid chromatography(HPLC)was employed to measure MC concentrations in various target samples.Results indicate that Microcystis spp.dominates as the primary MC producer in the DTR.The average concentrations of analyzed MCs in surface water ranged from 1.10 to 5.54μg/L,temporally and spatially.In sediment,average concentrations varied from 0.15 to 1.13μg/g wet weight(WW)temporally and from 0.41 to 0.72μg/g WW spatially.MCs were detected in different organs of fish species(Oreochromis sp.and Labiobarbus sp.)and in the entire soft tissues of bivalve(Corbicula sp.)and gastropod(Assiminea sp.).The highest observed MC concentration in July was 0.83±0.22μg/g WW in the intestines of fish Oreochromis sp.The presence of MCs in grass shrimp Palaemonetes sp.was observed solely in June,reaching a concentration of 0.28±0.19μg/g WW.This is the first report of MC accumulation in the grass shrimp Palaemonetes sp.during field collection.For the bivalve Corbicula sp.,the presence of analyzed MCs was consistent throughout the study period,except for March and September,with the highest concentrations in July at 0.77±0.1μg/g WW.Pearson correlation analysis revealed significant positive correlations between MCs in water and sediment with MC concentrations in aquatic animals,indicating the potential transfer of MCs across different trophic levels.The estimated daily intake values for analyzed MCs indicate that fish collected from the DTR are considered safe for consumption,as long as only the edible organs,such as the muscle,are consumed.However,bivalves or gastropods collected from the DTR are not safe for human consumption.This study underscored the importance of monitoring MC accumulation in aquatic animals used as food to mitigate adverse effects on human health.

A ratiometric fluorescent probe for hypoxanthine detection in aquatic products based on the enzyme mimics and fluorescence of cobalt-doped carbon nitride

A ratiometric fluorescent probe for hypoxanthine(Hx)detection was established based on the mimic enzyme and fluorescence characteristics of cobalt-doped graphite-phase carbon nitride(Co doped g-C_(3)N_(4)).In addition to emitting strong fluorescence,the peroxidase activity of Co doped g-C_(3)N_(4)can catalyze the reaction of O-phenylenediamine and H_(2)O_(2)to produce diallyl phthalate which can emit yellow fluorescence at 570 nm.Through the decomposition of Hx by xanthine oxidase,Hx can be indirectly detected by the generating hydrogen peroxide based on the measurement of fluorescent ratio I(F_(570)/F_(370)).The linear range was 1.7-272.2 mg/kg(R^(2)=0.997),and the detection limit was 1.52 mg/kg(3σ/K,n=9).The established method was applied to Hx detection in bass,grass carp,and shrimp,and the data were verified by HPLC.The result shows that the established probe is sensitive,accurate,and reliable,and can be used for Hx detection in aquatic products.

About Some Aspects of Use of Optical Sensors for Monitoring the Aquatic Environment

Multi-channel polarization optical technology is increasingly used for prompt monitoring of water systems.Optical devices during the assessment of water quality determine the intensity of light through the studied aquatic environment.Spectrophotometric devices measure the spectrum of weakening of light through the aquatic environment.Spectroellipsometric devices receive spectra in vertical and horizontal polarizations.The presented article develops an adaptive optical hardware and image system for monitoring water bodies.The system is combined.It consists of 2 parts:1)automated spectrophotometer-refractometer,and 2)adaptive spectroellipsometer.The system is equipped with a corresponding algorithmic and software,including algorithms for identifying spectral curves,databases and knowledge of spectral curves algorithms for solving reverse problems.The presented system is original since it differs from modern foreign systems by a new method of spectrophotometric and spectroellipsometric measurements,an original elemental base of polarization optics and a comprehensive mathematical approach to assessing the quality of a water body.There are no rotating polarization elements in the system.Therefore,this makes it possible to increase the signal-to-noise ratio and,as a result,improve measurement stability and simplify multichannel spectrophotometers and spectroellipsometers.The proposed system can be used in various water systems where it is necessary to assess water quality or identify the presence of a certain set of chemical elements.

Abiotic Factors Associated with Abundance Dynamics and Antibiotic Multidrug Resistance of Escherichia coli and Enterococcus faecalis Isolated from Some Ombessa Aquatic Systems (Central Cameroon Region)

The present study conducted in the town of Ombessa aims to assess the influence of abiotic factors on the abundance dynamics and antibiotic susceptibility of Escherichia coli and Enterococcus faecalis isolated from some aquatic systems from February to July 2022, monthly samples were taken at 10 water points used by the population (8 groundwater points and 2 surface water points). Samples were analyzed for physico-chemical parameters such as temperature, pH, electrical conductivity. Bacteriological variables such as BHAM, E. coli and E. faecalis abundances were also assessed. Antibiotic susceptibility of E. coli and E. faecalis was assessed using 06 antibiotics using the Kirby-Bauer diffusion disk method. The results show that bacterial abundances were the highest in surface waters. Bacterial densities were the highest in May and the lowest in February. The average densities recorded were 3845 CFU/100mL for BHAM, 380 CFU/100mL for E. coli and 14 CFU/100mL for E. faecalis in groundwater;and 8583 CFU/100mL for BHAM, 6878 CFU/100mL for E. coli and 812 CFU/100mL for E. faecalis in surface water. Antibiotic susceptibility tests showed that these bacterial species are sensitive to Gentamicin, Chloramphenicol, Azithromycin and Ciprofloxacin. They are all resistant to Trimethoprim/Sulfamethoxazole, E. coli is resistant to Doxycycline and E. faecalis has an intermediate sensitivity to Gentamicin. Overall, the Multiresistance to Antibiotics (MRA) indices obtained were above 0.2, indicating the presence of multidrug resistance in bacterial communities. The physico-chemical properties of the water varied over time and space, but on the whole remained below the threshold values of WHO guidelines. The degree of linkage between abiotic water variables and bacteriological parameters has shown that bacterial densities are more abundant in rainy seasons and increased O2 levels favor bacterial growth, while TSS, CO2 and dissolved nitrate levels affect the sensitivity of these bacterial species to antibiotics.

Purification Effects of Aquatic Vegetations on Lake Wetland Water Environment and Analysis of the Influencing Factors in Hongze Lake

[Objective] To study the purification effect of plant community on wetland water environment in Hongze Lake, and to provide references to the ecological restoration of this area. [Methed] The typical lakeside zone of Hongze Lake Wetland National Nature Reserve was taken as the study area. Through the field survey based on environmental characteristics of aquatic areas and non-aquatic areas, combined with laboratory test, the content changes of nutrients （N and P）, COD （chemical oxygen demand） and SD （transparency） levels in the water body of lake wetland were measured; the purification effect of the lake wetland ecosystem in the growth process of aquatic vegetation was quantitatively analyzed, and possible influ- encing factors were discussed. [Result] Aquatic vegetation could remove the TN, TP, COD, Chla in wetland water environment and had obvious effects on the changes of SD content. Competition between aquatic plants can inhibit the growth of algae and relieve the eutrophication of water body. [Conclusion] This study provided theoretical basis for ecological restoration and enhancement of self-purification capability in the lakeside zone of Hongze Lake.

Effects of Aquatic Plants on the Feature of Sediment Resuspension in Lake Taihu

[Objective] The aim was to study effects of aquatic plants on resuspen- sion of sediment in Lake Taihu. [Method] New resuspension simulator was used in the research. Elodea nuttalli, submerged plant, and Phragmites australis, emergent aquatic plant, were grown in substrate sludge with varied planting density set. Study of simulation experiment on the feature of sediment resuspension was carried on under shearing stress of 0.2-0.5 N/m2 and agitation of 1-30 min. [Result] Aquatic plant growing would effectively reduce seston concentration in water. Concentrations of final Suspended Particulate Matter （SPM） in experimental groups and control groups were as follows： water without plant〉coverage of 30% of Elodea nuttalli〉cov- erage of 60% of Elodea nuttalli〉Phragmites australis with concentration of 50 stock/m2〉 coverage of 90% of Elodea nuttalli〉Phragmites australis with concentration of 80 stock/m2〉Phragmites australis with concentration of 150 stock/m2; SPM concentration showed a tendency from increasing to stable with change of stirring time under dif- ferent shearing stresses： SPM concentration was of severe change at early stage in barrel without aquatic plant while change of SPM concentration in barrel with aquatic plant was quite mild and grew smaller with concentration increasing; SPM concentration was reduced much more if Phragmites australis planted compared with that of Elodea nuttalli; under different shearing stresses, reduction of SPM concen- tration by increase of Phragmites australis area was much more than by increase of Elodea nuttalli area. [Conclusion] It would provide powerful scientific reference for control on aquatic environment through comprehensive research on the feature of sediment resuspension.

Locality Improvement Technology for Auto-control System of Aquatic Seedling

[Objective] The aim was to improve part of auto-control system of aquatic seedling breeding and to lay foundation for highly-efficient and stable use of the sys- tem. [Method] The executive and drive modules of the auto-control system were im- proved, after which real-time monitor, data display and alarm modules were tested on time. [Result] In the test, for the improved system, stability and sensitivity were enhanced; different components matched better; transmitting electric resistanc6 was reduced. [Conclusion] The research provides references for auto-control of water temperature and dissolved oxygen, and faults clearing in aquatic seedling breeding.

Mechanism of microcystin removal from eutrophicated source water by aquatic vegetable bed

For purifying raw water for tap water treatment, the aquatic vegetable bed （AVB） experiment has been carded out in a hypertrophic waterfront of Taihu Lake, China. The average removal rates of total microcystin-RR and microcystin-LR are 63.0% and 66. 7%, respectively. Experiments indicate that lpomoea aquatica can absorb microcystin by using enzyme-linked immunosorbent assay （ELISA）, and the roots absorb more toxins than leaves and stems. Fluorescence in situ hybridization （FISH） is used to analyze the density of microcystin degrading bacteria in the AVB sediment. Two species of microcystin degrading bacteria are detected, which indicate that microcystin bio-degradation process happened in the AVB. Protozoa and metazoa are abundant in root spheres. Aspidisca sp., Vorticella sp., Philodina sp., and Lecane sp. are dominant species. The predation functions of protozoa and metazoa have a positive effect on the removal of cyanobacteria and microcystin.

Purification and Antimicrobial Assay of an Antimicrobial Protein from a Biocontrol Bacterium Strain K2-1 against Aquatic Pathogens

[Objective] The aim of this study was to purify an antimicrobial protein from a biocontrol bacterium strain K2-1 and analyze its antimicrobial activity in vitro against some typical aquatic pathogens. [Method] The antimicrobial protein was ob- tained by using ammonium sulfate precipitation and Sephadex chromatography combined with hot water bath. The antimicrobial assay was conducted by means of agar diffusion technique, using Vibrio alginolyticus, Aeromonas hydrophila, Aeromonas. Sobria, Pseudomonas fluorescens, Vibrio Parahaemolyticus, Vibrio har- veyi and Vibrio anguillarum as test bacteria. [Result] Antimicrobial protein APK2 can be derived from fermentation broth of strain K2-1 and purified to the chromatogra- phy pure level by the methods provided, the final yield of the antimicrobial compo- nent is approximately 0.08%. This antimicrobial protein had a strong antimicrobial activity against the growth of most those bacteria. [Conclusion] The results show that APK2 could be a potential alternative to replace chemical antimicrobial agent in the control and prevention of aquatic diseases.

The Development Status quo and Strategy of Aquatic Vegetables in Hunan

This paper reviews the development of aquatic vegetable production and research in Hunan. The advantages of aquatic vegetable industry in Hunan are discussed in detail on its location, brand, market, planting and processing. And the development strategies of the above-mentioned industry are further analyzed in the paper, such as variety resources, breeding and industrialization.

Photosynthetic Responses to Inorganic Carbon in Ulva lactuca Under Aquatic and Aerial States

Intertidal macroalgae experience continual alternation of photosynthesis between aquatic state at high tide and aerial state at low tide. The comparative photosynthetic responses to inorganic carbon were investigated in the common intertidal macroalga Ulva lactuca L. along the coast of Shantou between aquatic and aerial state. The inorganic carbon dissolved in seawater at present could fully (at 10 ℃ or 20 ℃) or nearly (at 30 ℃) saturate the aquatic photosynthesis of U. lactuca . However, the aerial photosynthesis was limited by current ambient atmospheric CO 2 level, and such a limitation was more severe at higher temperature (20-30 ℃) than at lower temperature (10 ℃). The carbon_saturated maximal photosynthesis of U. lactuca under aerial state was much greater than that under aquatic state at 10 ℃ and 20 ℃, while the maximal photosynthesis under both states was similar at 30 ℃. The aerial values of K m (CO 2) for photosynthesis were higher than the aquatic values. On the contrary, the values of apparent photosynthetic CO 2 conductance under aerial state were considerably lower than that under aquatic state. It was concluded that the increase of atmospheric CO 2 would enhance the primary productivity of U. lactuca through stimulating the photosynthesis under aerial state during low tide.

Progress in the research on aquatic environmental nonpoint source pollution in China

In this paper, the authors reviewed the development process of China's research on aquatic environmental nonpoint pollution, and the situation of nonpoint source pollution in east China was also analyzed.

A Critical Review on Superchilling Preservation Technology in Aquatic Product

aquatic product, known as one of the good resources for white meat, has been widely accepted by the consumers due to its high protein, low fat, especially low cholesterol. With the fast development of living standards around the world, the consumer demands for high quality, nutrition, safety and freshness of ifshery food are increasing. Thus, high efifcient preservation technologies for aquatic products become particularly important. Superchilling is one of the controlled-temperature preservation technologies for seafood. Aquatic products can be kept in better quality under superchilling conditions. This review introduced the principle and development of superchilling process, mainly focusing on research progresses and technical dififculties of superchilling. The growth mechanism of ice crystals and the feasibility of application of computational lfuid dynamics in analyzing the temperatures variation and ice crystals during superchilling progress were also discussed, which will provide theoretical foundation for its improvement and application.

Aquatic exercise program-modulated oxidative stress markers in patients with Parkinson's disease

Parkinson's disease is a neurodegenerative disease.Oxidative stress,i.e.,the imbalance between the generation of reactive oxygen species and the antioxidant defense capacity of the body,plays an important role in the pathogenesis of this disease.Physical exercise can regulate oxidative stress.The purpose of this study was to analyze the short-and long-term effects of an aquatic exercise program on oxidative stress levels in patients with Parkinson's disease.The aquatic exercise program was carried out during 1 month with two sessions per week(1 hour/session).Blood samples were collected at four different time points:pre-intervention,immediately,48 hours,and 30 days after the first session of aquatic exercise program.Our results revealed that water-based programs modulated antioxidant enzyme activity,increased superoxide dismutase activity,reduced catalase activity,and increased the ratio of superoxide dismutase activity to catalase activity in patients with Parkinson's disease.Compared with pre-intervention and 48 hours after the first session of aquatic exercise program,superoxide dismutase activity was higher and catalase activity was lower immediately and 30 days after the first session.Our results demonstrated that aquatic exercise program could modulate oxidative stress,mainly by the effect of antioxidant enzyme activity.These results could better help understand the target of oxidative stress in Parkinson's disease.This study was approved by the Ethics Committee of Centro Universitário Metodista IPA(approval No.1.373.911)on August 9,2019 and registered with REBEC(registration number:RBR-6 NJ4 MK).

Removal of hexavalent chromium in aquatic solutions by pomelo peel

This study investigated the removal of hexavalent chromium(Cr(VI)) in aqueous solutions using pomelo peel(PP) and FeCl3-modified pomelo peel(FPP) as novel biomass adsorbents.Batch adsorption experiments were performed to evaluate the effects of pH,time,temperature,initial concentration,and adsorbent dose on Cr(VI) removal by PP and FPP.The results show that the maximum adsorption capacity of Cr(VI)was 21.55 mg/g for FPP and 0.57 mg/g for PP at a pH of 2.0 and a temperature of 40℃.The surface shape,microstructure,and chemical composition of FPP were analyzed with scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),and energy dispersive spectroscopy(EDS),and compared with those of PP.The results show that the adsorption performance of FPP was much better than that of PP,indicating that FPP can be an alternative high-efficiency adsorbent for Cr(VI) removal.

Late Cretaceous Aquatic Angiosperms from Jiayin,Heilongjiang,Northeast China

Three taxa of Late Cretaceous aquatic angiosperms, Queruexia angulata （Lesq.） Krysht., Cobbania corrugata （Lesq.） Stockey et al. and Nelumbites cf. extenuinervis Upchurch et al. from Jiayin of Heilongjiang, NE China, are described in detail. Among them, Cobbania and Nelumbites from the Upper Cretaceous in China are reported for the first time. The aquatic angiosperm assemblage of Queruexia-Cobbania-Nelumbites appears to imply a seasonal, warm and moist environment in the Jiayin area during the Santonian-Campanian time.

Cumulative Risk Assessment of Exposure to Heavy Metals through Aquatic Products in China

Objective This study aimed to assess the risk of cumulative exposure to Pb,Cd,Hg,and iAs through aquatic products consumed by Chinese people.Methods Heavy metal concentration data were obtained from the national food contamination monitoring program during 2013–2017.Consumption data were derived from the China National Food Consumption Survey in 2014 and the relative potency factor(RPF)method was used to estimate cumulative exposure for neurotoxicity and nephrotoxicity.Results The results demonstrated that the cumulative exposure based on neurotoxicity was below the lower confidence limit on benchmark doses of lead(BMDL01)for nephrotoxicity and the cumulative exposures were all lower than the provisional tolerable monthly intake(PTMI)of Cd.However,the margin of exposure values(MOEs)of the cumulative exposures for neurotoxicity in the 2–6 year-old group was close to 1 and the cumulative exposure level for nephrotoxicity accounted for 90.21%of the PTMI.Conclusion The cumulative exposures of the 2–6 year-old group to the four heavy metals did not reach(but came close to)the corresponding safety threshold for both neurotoxicity and nephrotoxicity.Given that there are still other food sources of these four heavy metals,it is necessary to more closely study their cumulative health effects.

Water Quality Purifying Effect of Five Kinds of Aquatic Plants in Winter

[Objective] The aim was to compare the water quality purifying effect of five kinds of aquatic plants.[Method] Model of surface flow wetlands was constructed in the river bank of Jialu River in Zhengzhou City,and five kinds of aquatic plants which could grow normally in winter were selected and introduced for screening experiment of aquatic plants.[Result] Five kinds of plants were growing well,and they showed strong cold resistance.However,there were some differences on water quality purifying ability among five kinds of aquatic plants,in which Oenanthe javanica and Elodea canadensis performed better on removing the TN,the removal rate was 44% and 41% respectively; Iris sibirica and O.javanica showed better performance on the removal of TP,the removal rate was 41% and 37% respectively; there was little difference on the removal effect on NH4^＋-N among five kinds of plants,in which E.Canadensis performed best with the removal rate of 73%,followed by O.javanica （the removal rate was 71%）,and the removal rate of I.sibirica,Rumex acetosa and Potamogeton crispus were 70%; there was no significant purification effect of five kinds of plants on CODCr,in which I.sibirica and R.acetosa performed better,and the removal rate was 14% and 13% respectively.[Conclusion] The emerging plants and submerged plants hydrophytes could be used to construct floating aquatic macrophyte-based treatment system （FAMS） in wetland vegetation allocation to improve the purification effect of wetlands of North China in winter.

Toxic effects of crude-oil-contaminated soil in aquatic environment on Carassius auratus and their hepatic antioxidant defense system

Under the indoor simulant conditions, toxic effects of crude-oil-contaminated soil which was put into aquatic environment on the young fishes Carassius auratus and their hepatic antioxidant system after a 20-d exposure were investigated. Results showed that the relationship between the mortality of C. auratus and the exposed doses could be divided into 3 phases： fishes exposed to the low dose groups （0.5-5.0 g/L） were dead due to the ingestion of crude-oil-contaminated soils in aquatic environment; at the medium dose groups （5.0-25.0 g/L） fishes were dead due to the penetration of toxic substances; at the high dose groups （25.0-50.0 g/L） fishes were dead due to environmental stress. The highest mortality and death speed were found in the 1.0 g/L dose group, and the death speed was sharply increased in the 50.0 g/L dose group in the late phase of exposure. The activities of superoxide dismutase （SOD）, catalase （CAT） and glutathione S-transferase （GST） and the content of malaondialdehyde （MDA） in the hepatic tissues of C. auratus were induced significantly. The activity of SOD was increased and then decreased. It was significantly inhibited in the 50.0 g/L dose group. The activity of CAT was highly induced, and restored to a level which is little more than the control when the exposed doses exceeded 10.0 g/L. The activity of GST was the most sensitive, it was significantly induced in all dose groups, and the highest elevation was up to 6 times in the 0.5 g/L dose group comparing with the control. The MDA content was significantly elevated in the 50.0 g/L dose group, and the changes of the MDA content were opposite with the changes of GST activity.

Biophoton emission， free radical and toxicity of benzene to aquatic biosystems

The observation on biophoton emission, free radical and toxicity of benzene to zebra fish and carp hepatic microsome has demonstrated that there is the corresponding relationship between them by means of 60 Coγ radiolysis. Free radicals play a key role in this relationship. A common photon originates of two biosystems are the excited species including singlet and triplet molecules (1O2 and C=0) as well as hydrocyclohexadienyl radical.OH and so on. OH, to a certain extent, directly participates in photon emission and toxicity of benzene to aquatic biosystems.These are the conclusions, but these are also problems. With the solution of the latters,model established in this work could be expected that it will be favorable for the development of photon-toxicology.