Water eutrophication has become a worldwide environmental problem in recent years, and understanding the mechanisms of water eutrophication will help for prevention and remediation of water eutrophication. In this paper, recent advances in current status and major mechanisms of water eutrophication, assessment and evaluation criteria, and the influencing factors were reviewed. Water eutrophication in lakes, reservoirs, estuaries and rivers is widespread all over the world and the severity is increasing, especially in the developing countries like China. The assessment of water eutrophication has been advanced from simple individual parameters like total phosphorus, total nitrogen, etc., to comprehensive indexes like total nutrient status index. The major influencing factors on water eutrophication include nutrient enrichment, hydrodynamics, environmental factors such as temperature, salinity, carbon dioxide, element balance, etc., and microbial and biodiversity. The occurrence of water eutrophication is actually a complex function of all the possible influencing factors. The mechanisms of algal blooming are not fully understood and need to be further investigated.
Animals ; Environment ; Eukaryota ; growth & development ; isolation & purification ; Eutrophication ; Humans ; Water ; analysis ; Water Microbiology

OBJECTIVES: Tricalcium phosphate and calcium hydrogenorthophosphate are high production volume chemicals, mainly used as foodstuff additives, pharmaceuticals, lubricants, synthetic resin, and disinfectants. Phosphate has the potential to cause increased algal growth leading to eutrophication in the aquatic environment. However, there is no adequate information available on risk assessment or acute and chronic toxicity. The aim of this research is to evaluate the toxic potential of phosphate compounds in the aquatic environment. METHODS: An aquatic toxicity test of phosphate was conducted, and its physico-chemical properties were obtained from a database recommended in the Organization for Economic Cooperation and Development (OECD) guidance manual. An ecotoxicity test using fish, Daphnia, and algae was conducted by the good laboratory practice facility according to the OECD TG guidelines for testing of chemicals, to secure reliable data. RESULTS: The results of the ecotoxicity tests of tricalcium phosphate and calcium hydrogenorthophosphate are as follows: In an acute toxicity test with Oryzias latipes, 96 hr 50% lethal concentration (LC50) was >100 (measured:>2.14) mg/L and >100 (measured: >13.5) mg/L, respectively. In the Daphnia test, 48 hr 50% effective concentration (EC50) was >100 (measured: >5.35) mg/L and >100 (measured: >2.9) mg/L, respectively. In a growth inhibition test with Pseudokirchneriella subcapitata, 72 hr EC50 was >100 (measured: >1.56) mg/L and >100 (measured: >4.4) mg/L, respectively. CONCLUSIONS: Based on the results of the ecotoxicity test of phosphate using fish, Daphnia, and algae, L(E)C50 was above 100 mg/L (nominal), indicating no toxicity. In general, the total phosphorus concentration including phosphate in rivers and lakes reaches levels of several ppm, suggesting that phosphate has no toxic effects. However, excessive inflow of phosphate into aquatic ecosystems has the potential to cause eutrophication due to algal growth.
Calcium ; Daphnia ; Disinfectants ; Ecosystem ; Eutrophication ; Lakes ; Lubricants ; Oryzias ; Phosphorus ; Resins, Synthetic ; Risk Assessment ; Rivers ; Toxicity Tests ; Toxicity Tests, Acute

OBJECTIVEImpact of the presence of bacteria associated with a marine dinoflagellate, Alexandrium tamarense CI01, on the growth and toxin production of the algae in batch culture was investigated.

METHODSPronounced changes in the activities of the algal culture were observed when the culture was treated with different doses of a mixture of penicillin and streptomycin.

RESULTSIn the presence of antibiotics at the initial concentration of 100 u/mL in culture medium, both algal growth and toxin yield increased markedly. When the concentration of antibiotics was increased to 500 u/mL, the microalgal growth was inhibited, but resumed in a few days to eventually reach the same level of growth and toxin production as at the lower dose of the antibiotics. When the antibiotics were present at a concentration of 1 000 u/mL, the algal growth was inhibited permanently.

CONCLUSIONSThe results indicate that antibiotics can enhance algal growth and toxin production not only through their inhibition of the growth and hence competition for nutrients, but also through their effects on the physiology of the algae.

Animals ; Anti-Bacterial Agents ; pharmacology ; Bacteria ; Dinoflagellida ; microbiology ; pathogenicity ; Eutrophication ; Marine Toxins ; biosynthesis ; Penicillins ; pharmacology ; Saxitoxin ; Streptomycin ; pharmacology

OBJECTIVEThis study was to assess the influence of interaction of combination of immobilized nitrogen cycling bacteria (INCB) with aquatic macrophytes on nitrogen removal from the eutrophic waterbody, and to get insight into different mechanisms involved in nitrogen removal.

METHODSThe aquatic macrophytes used include Eichhornia crassipes (summer-autumn floating macrophyte), Elodea nuttallii (winter-growing submerged macrophyte), and nitrogen cycling bacteria including ammonifying, nitrosating, nitrifying and denitrifying bacteria isolated from Taihu Lake. The immobilization carriers materials were made from hydrophilic monomers 2-hydroxyethyl acrylate (HEA) and hydrophobic 2-hydroxyethyl methylacrylate (HEMA). Two experiments were conducted to evaluate the roles of macrophytes combined with INCB on nitrogen removal from eutrophic water during different seasons.

RESULTSEichhornia crassipes and Elodea nuttallii had different potentials in purification of eutrophic water. Floating macrophyte+bacteria (INCB) performed best in improving water quality (during the first experiment) and decreased total nitrogen (TN) by 70.2%, nitrite and ammonium by 92.2% and 50.9%, respectively, during the experimental period, when water transparency increased from 0.5 m to 1.8 m. When INCB was inoculated into the floating macrophyte system, the populations of nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 2 orders of magnitude compared to the un-inoculated treatments, but ammonifying bacteria showed no obvious difference between different treatments. Lower values of chlorophyll a, COD(Mn), and pH were found in the microbial-plant integrated system, as compared to the control. Highest reduction in N was noted during the treatment with submerged macrophyte+INCB, being 26.1% for TN, 85.2% for nitrite, and 85.2% for ammonium at the end of 2nd experiment. And in the treatment, the populations of ammonifying, nitrosating, nitrifying, and denitrifying bacteria increased by 1 to 3 orders of magnitude, as compared to the un-inoculated treatments. Similar to the first experiment, higher water transparency and lower values of chlorophyll a, COD(Mn) and pH were observed in the plant+ INCB integrated system, as compared to other treatments. These results indicated that plant-microbe interaction showed beneficial effects on N removal from the eutrophic waterbody.

Biodegradation, Environmental ; Eutrophication ; physiology ; Magnoliopsida ; metabolism ; Nitrogen ; isolation & purification ; pharmacokinetics ; Systems Integration ; Water Microbiology ; Water Pollutants, Chemical ; isolation & purification ; pharmacokinetics ; Water Purification ; methods

Agricultural activities, including stock-farming, planting industry, and fish aquaculture, can affect the physicochemical and biological characters of freshwater lakes. However, the effects of pollution producing by agricultural activities on microbial ecosystem of lakes remain unclear. Hence, in this work, we selected Honghu Lake as a typical lake that is influenced by agriculture activities. We collected water and sediment samples from 18 sites, which span a wide range of areas from impacted and less-impacted areas. We performed a geospatial analysis on the composition of microbial communities associated with physicochemical properties and antibiotic pollution of samples. The co-occurrence networks of water and sediment were also built and analyzed. Our results showed that the microbial communities of impacted and less-impacted samples of water were largely driven by the concentrations of TN, TP, NO-N, and NO-N, while those of sediment were affected by the concentrations of Sed-OM and Sed-TN. Antibiotics have also played important roles in shaping these microbial communities: the concentrations of oxytetracycline and tetracycline clearly reflected the variance in taxonomic diversity and predicted functional diversity between impacted and less-impacted sites in water and sediment samples, respectively. Furthermore, for samples from both water and sediment, large differences of network topology structures between impacted and less-impacted were also observed. Our results provide compelling evidence that the microbial community can be used as a sentinel of eutrophication and antibiotics pollution risk associated with agricultural activity; and that proper monitoring of this environment is vital to maintain a sustainable environment in Honghu Lake.
Agriculture ; Animals ; Anti-Bacterial Agents ; analysis ; China ; Eutrophication ; Geologic Sediments ; chemistry ; microbiology ; Lakes ; chemistry ; microbiology ; Microbiota ; Risk Factors ; Water Pollutants, Chemical ; analysis

The frequency and scale of Harmful Algal Bloom (HAB) and marine algal toxin incidents have been increasing and spreading in the past two decades, causing damages to the marine environment and threatening human life through contaminated seafood. To better understand the effect of HAB and marine algal toxins on marine environment and human health in China, this paper overviews HAB occurrence and marine algal toxin incidents, as well as their environmental and health effects in this country. HAB has been increasing rapidly along the Chinese coast since the 1970s, and at least 512 documented HAB events have occurred from 1952 to 2002 in the Chinese mainland. It has been found that PSP and DSP toxins are distributed widely along both the northern and southern Chinese coasts. The HAB and marine algal toxin events during the 1990s in China were summarized, showing that the HAB and algal toxins resulted in great damages to local fisheries, marine culture, quality of marine environment, and human health. Therefore, to protect the coastal environment and human health, attention to HAB and marine algal toxins is urgently needed from the environmental and epidemiological view.
Amnesia ; chemically induced ; Animals ; China ; epidemiology ; Ciguatoxins ; toxicity ; Diarrhea ; chemically induced ; Dinoflagellida ; Environment ; Eukaryota ; chemistry ; Eutrophication ; Fisheries ; Food Contamination ; Foodborne Diseases ; epidemiology ; etiology ; Humans ; Kainic Acid ; analogs & derivatives ; poisoning ; Lethal Dose 50 ; Marine Toxins ; chemistry ; poisoning ; toxicity ; Neurotoxicity Syndromes ; etiology ; Okadaic Acid ; poisoning ; Oxocins ; poisoning ; Paralysis ; chemically induced ; Seawater ; Shellfish Poisoning

OBJECTIVETo establish the indexes and weights of risk assessment of shellfish poisoning outbreak caused by red tide.

METHODSThe risk assessment indexes were developed with the methods of literature review, brainstorm and expert consultation, and the weights of indexes were calculated by the method of analytic hierarchy process. The established indexes contained the risk possibility, impacts of public health, population vulnerability and resilience. The relative risk indexes(integrated risk indexes) of different shellfish poisoning were computed by combining hierarchy process and TOPSIS methods. Moreover, the weights of indexes were further used to generate absolute risk values by multiplying indexes.

RESULTSFour primary indexes and 17 secondary indexes were identified for risk assessment of shellfish poisoning outbreak. Of 17 secondary indexes, the knowing rate of shellfish poisoning, medical accessibility, the number of people being affected, laboratory testing capacity and the habits of eating seafood of local residents had relatively large weights (0.0876, 0.0840, 0.0716, 0.0703 and 0.0644, respectively), which accounted for nearly 38% of the total weight. All consistency ratio (CR) were less than 0.1. The index system was applied in Cangnan county of Zhejiang province. The results showed the relative risk indexes of paralytic shellfish poisoning (PSP), diarrhetic shellfish poisoning (DSP), neurotoxic shellfish poisoning (NSP) and amnesic shellfish poisoning (ASP) were 0.4526, 0.7116, 0.1657 and 0.2884, and the absolute risk values were 0.2542, 0.2668, 0.1907 and 0.2184, respectively. The risk orders of the 4 kinds of shellfish poisoning sorted by relative risk indexes and absolute risk values were consistent.

CONCLUSIONSThe indexes and weights of risk assessment of shellfish poisoning outbreak caused by red tide are established, which can provide scientific advice for prevention and control of shellfish poisoning outbreak.

Animals ; Disease Outbreaks ; Harmful Algal Bloom ; Humans ; Marine Toxins ; Risk Assessment ; Seafood ; Shellfish Poisoning

OBJECTIVETo explore the potential reporter gene assay for the detection of sodium channel-specific toxins in shellfish as an alternative for screening harmful algal bloom (HAB) toxins, considering the fact that the existing methods including HPLC and bioassay are inappropriate for identifying HAB toxins which poses a serious problem on human health and shellfish industry.

METHODSA reporter plasmid pEGFP-c-fos containing c-fos promoter and EGFP was constructed and transfected into T24 cells using LipofectAMINE 2000. Positive transfectants were screened by G418 to produce a pEGFP-c-fos-T24 cell line. After addition of increasing neurotoxic shellfish poison (NSP) or GTX2,3, primary components of paralytic shellfish poison (PSP), changes in expression of EGFP in the cell line were observed under a laser scanning confocal microscope and quantified with Image-pro Plus software.

RESULTSDose-dependent changes in the intensity of green fluorescence were observed for NSP in a range from 0 to 10 ng/mL and for GTX2,3 from 0 to 16 ng/mL.

CONCLUSIONpEGFP-c-fos-T24 can be applied in detecting HAB toxins, and cell-based assay can be used as an alternative for screening sodium channel-specific HAB toxins.

Animals ; Biological Assay ; Cell Line, Tumor ; Genes, Reporter ; physiology ; Green Fluorescent Proteins ; Harmful Algal Bloom ; physiology ; Humans ; Plasmids ; Proto-Oncogene Proteins c-fos ; genetics ; metabolism ; Shellfish ; analysis ; Sodium Channels ; Toxins, Biological ; chemistry ; toxicity