Nutrient Salts Research Articles

Assessing nutrient salts and trace metals distributions in the coastal water of Jeddah, Red Sea.

In this study, eighteen sites at Jeddah coastal area, Red Sea, have been assessed for water quality status, depending on nutrients, metals, Chlorophyll-a (Chl-a) and physical variables during 2018 and 2019. The investigated parameters of the Water Quality Index (WQI) are temperature, pH, salinity, dissolved oxygen (DO), DO saturation, oxidizable organic matter (OOM), suspended particulate matter (SPM), Chl-a, ammonium, nitrite, nitrate, total nitrogen, reactive phosphate, total phosphorus, silicate, Zn, Fe, Mn Cu, Cd, Pb, and Ni. The results revealed that the pH values were slightly alkaline with a range of 7.85–8.20. The results of other parameters were as follow: salinity (36.95–42.61PSU), DO (5.22–6.67 mg/L), OOM (0.40–1.23 mg/L), SPM (12.39–21.5 mg/L), Chl-a (0.10–0.83 µg/L). The range of nutrients (μM) were 0.07–0.22, 0.45–1.47, 9.62–18.64, 23.31–57.65, 0.05–0.15, 0.55–2.78 and 2.54–5.51 for NH4/N, NO2/N, NO3/N, TN, PO4/P, TP and SiO4/Si, respectively. Cluster analysis was used to classify the stations studied. From the current study, five clusters were found, indicating the need to perform cluster analysis in the water quality assessment process to confirm the durability and consistency of the data discovered in the current application.

Distribution of Nutrient Salts and Chlorophyll-a in Surface Water along the Gulf of Aden and Arabian Sea Coast, Yemen

The distribution of inorganic nutrient salts (ammonium, nitrite, nitrate, phosphate and silicate) and phytoplankton chlorophyll-a (Chl-a) were investigated in the Gulf of Aden and along the Arabian Sea coast, Yemen. Seventy two surface water samples were collected during cruises in August 2014 and January 2015. The sampled area extends from As Suqayyah in the west of the Gulf of Aden to Hawf in the east. The study showed that the average values of nutrient salts (μg/l) in waters collected in August 2014 and January 2015 were 0.83 and 0.60, 10.98 and 10.03, 16.41 and 14.73, 10.36 and 8.76, and 29.72 and 22.67 for ammonium, nitrite, nitrate, phosphate and silicate, respectively. The average values of Chl-a (mg/m3) in August 2014 and January 2015 were 0.26 and 0.21, respectively. The results showed that nitrate levels were very high but those of ammonium very low. This may reflect the oxidation of ammonia to nitrite and then nitrate, leading to a very favorable ratio of ammonia and nitrate values. The low levels of dissolved inorganic nitrogen (DIN)compounds, (ammonium, nitrite, and nitrate), phosphate, silicate and Chl-a indicated that the southern coast of Yemen is not in a eutrophic condition. The highest nutrient salt values were in the eastern part of the study area, and may have resulted from water originating from the Indian Ocean and upwelling. Statistical analysis to seek correlations between nutrient salts and Chl-a show very good to excellent correlation, which may be due toconstant coastal environment.

Bacterial community colonization on tire microplastics in typical urban water environments and associated impacting factors

Only limited information is available on bacterial communities’ dynamics on tire microplastics in urban water environments. This study exploited 16S rDNA high-throughput sequencing to characterize bacterial communities on tire microplastics, using three different tire brands and tire sizes, in two typical urban water environments, including an influent pond of constructed wetland (CW) and its subsequent effluent into a landscape river (LR) during three different periods, namely, 1 month, 3 and 6 months. Results showed that the abundance of bacterial colonization on tire microplastics will increase over time. Proteobacteria, Bacteroidetes were the dominant bacteria at a phylum level, although they exhibited dynamic changes. At a genus level, the identifiable bacteria found in tire microplastics was generally the common bacteria in wastewater discharge, such as Aquabacterium and Denitratisoma. Additionally, alpha diversity showed no significant differences in bacterial communities at the same locations. While beta diversity showed that the bacterial communities on the tire microplastics in the two locations was different. BugBase revealed that tire microplastics could support pathogenic bacteria in urban water environments. PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) indicated that the abundance of microorganisms associated with metabolism and degradation increased with time. Moreover, the ambient environmental factors were the main influencing factors of bacterial communities on tire microplastics. Herein, the contribution rate of nutrient salts (NO2-N, NO3-N, NH4-N, CODcr) was approximately 63%, and that of environmental physical factors of T and pH was 50%. While physicochemical factors, including particle size, contact angle, element content only had a slight impact. Accordingly, tire microplastics, as an emerging environmental pollutant, can act as carries for bacterial colonization and propagation, particularly harmful microorganisms. Therefore, the obtained findings can provide new insight into potential risks of harmful microorganisms that colonize tire microplastics in urban water environments.

A Method for Monitoring the Spatial Distribution of Nutrients from the Perspective of Landscape Ecology

Zhang, W., 2020. A method for monitoring the spatial distribution of nutrients from the perspective of landscape ecology. In: Malvárez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 182–186. Coconut Creek (Florida), ISSN 0749-0208.In order to quantify the spatial distribution characteristics of nutrient salts and monitor the ecological landscape characteristics of the spatial distribution of nutrients, a monitoring model based on fuzzy set theory for spatial distribution of ecological landscape characteristics of nutrient salts is proposed, in which the spatial distribution of nutrient salts is used to cluster the ecological landscape. The fuzzy constraint parameter model of ecological landscape feature monitoring of spatial distribution of nutrient salts is constructed based on the constraint index set, such as beauty, landscape natural fusion and energy saving and environmental protection, and so on. The analytic hierarchy process (AHP) is used to construct the statistical analysis model of spatial distribution monitoring of nutrient salts from the perspective of landscape ecology, and the fuzzy set theory is used to design the optimal control model of the monitoring model of spatial distribution characteristics of nutrient salts. The ecological landscape feature monitoring problem of nutrient spatial distribution is transformed into the binary programming problem of seeking fuzzy set. The spatial distribution characteristic map analysis and principal component feature extraction method of nutrient salt are adopted. The spatial distribution of nutrient salts in landscape is optimized to monitor the spatial distribution characteristics of nutrient salts. The results of empirical analysis show that the monitoring of ecological landscape characteristics of spatial distribution of nutrients is more accurate, more stable and more efficient.

Phytoplankton diversity and community responses to physicochemical variables in mangrove zones of Guangzhou Province, China.

The phytoplankton diversity and community response to physicochemical variables in mangrove zones of Guangdong Province along the South China coast was investigated from October to December, 2017. This study was set to investigate the phytoplankton community structure in the mangrove zone and assess the relationship between the physicochemical variables and phytoplankton species diversity. Physicochemical variables such as water temperature, total dissolve solids (tds), pH, salinity, turbidity, electrical conductivity (EC) and nutrient salts were measured in situ across the 27 stations. A total of 451 species of phytoplankton were identified belonging to 10 groups (Bacillariophta > Cyanophyta > Chlorophyta > Euglenophyta > Dinoflagellate > Eubacteria > Ochrophyta > Crytophyta > Rhodophyta > Charophyta) and quantified to constitute a standing crop of 7.11 × 108 cells dm-3. The principal component analysis (PCA) reveals that reactive nitrate, phosphate, electrical conductive (EC) and turbidity were the best abiotic factors that controlled the phytoplankton community structure in the area. However, Cannon Corresponding Analysis and Pearson correlation have explicitly revealed the impact of reactive nitrate, phosphate, EC and turbidity on the phytoplankton community structure. For instance, the CCA ordination revealed that species richness and evenness were positively influenced by reactive nitrate but negatively affected by EC, turbidity and water temperature. Diatoms were mostly controlled by total dissolved solids (tds) and salinity, whereas Euglena, cyanobacteria and green algae were impacted EC and turbidity, apart from the general contribution of the nutrient salts as delineated by CCA ordination. The Shannon diversity index value exposed different levels of organic pollution across the mangrove zone of which GD37 was the most impacted station.

Temporal and Spatial Distribution Characteristics and Difference Analysis of Nitrogen and Phosphorus in Daihai Lake

Based on the historical monitoring survey data from 2018 to 2019, the temporal and spatial distribution characteristics and main influencing factors of nitrogen and phosphorus in the overlying water in Daihai Lake were analyzed, and the differences of the temporal and spatial distribution were discussed. The results showed that the content of total nitrogen and total phosphorus in the overlying water was at a high level, especially the total nitrogen content was obviously higher than that in other lakes in China. The content of total nitrogen ranged from 3.29 mg·L-1 to 4.99 mg·L-1, with a mean value of (3.93±0.33) mg·L-1; the content of total phosphorus ranged from 0.063 mg·L-1 to 0.163 mg·L-1, with a mean value of (0.111±0.023) mg·L-1. In spring and summer, the content of total nitrogen and total phosphorus in the overlying deep water from the middle of the lake was significantly higher than that in the surrounding area. In autumn, the contents decreased from east to west, and in winter, the contents in the shallow water of the southern area were higher than that in the northern area. Nitrogen and phosphorus in the overlying water were mainly in the dissolved state, and the proportions of total dissolved nitrogen and phosphorus were 86.62% and 77.84%, respectively. The dissolved nitrogen was dominated by nitrate, whereas dissolved phosphorus was dominated by organic phosphorus. The concentration of lake water and the release of endogenous nutrient salts are the main reasons for the high total nitrogen and phosphorus. To prevent further deterioration of water quality, it is suggested to carry out endogenous treatment and ecological restoration in combination with engineering measures.

Evaluation of River Water Quality in Agricultural Watershed with the Environmental Standards

Japan has general environmental standards for organic matter in its public water bodies. However, there are no environmental standards for nutrient salts such as phosphorus (P) and nitrogen (N) in river water. In this study, the water quality of rivers at normal water level was evaluated in agricultural watersheds by focusing on water quality standards. The investigated sites are in the Tokachi area (24 watersheds; upland and dairy farming) and the Nemuro area (11 watersheds; large-scale dairy farming), which are in Eastern Hokkaido. The investigations were carried out in the two agricultural areas in 2005, 2006 and 2012. Electrical conductivity (EC) and water temperature were measured at the same time as river water samples were collected in the two areas. Water quality was analyzed for potential of hydrogen (pH), biochemical oxygen demand (BOD), suspended solids (SS), total phosphorus (T-P), total nitrogen (T-N) and other values. Most of the values associated with organic matter, such as pH, BOD and SS, in river water were within the thresholds for the standards of The Environmental Standards Concerning the Conservation of the Living Environment (Rivers). In contrast, some values of nutrient salts (N and P) exceeded the thresholds (T-P≦0.1 mg/L, T-N≦1.0 mg/L). Many of the watersheds in the Tokachi area had T-N concentration in excess of 1.0 mg/L. This suggests that the concentrations of nutrient salts (P and N) increase with increases in agricultural land development in a watershed. For the evaluation of river water quality in agricultural watersheds, it was found to be necessary to measure both organic matter and nutrient salts as indices of water quality. And it was found that controlling the runoff of P and N from agricultural land is essential for water quality conservation in public water bodies.

Study on the Release of Nutrient Salt from Soil in Baiyangdian Area

As a national key protection and restoration project, Baiyangdian has an important and far-reaching significance. As one of Baiyangdian's lakes, Zaozhadian needs to adapt to local conditions and adopt a near-natural method of "returning farmland to wetland" for treatment and restoration. According to the difference of total nitrogen (TN) and total phosphorus (TP) content in the soil, soil nutrient release experiments were conducted to explore the effect of soil nutrient release on the quality of overlying water. The results showed that the amount of nutrients released was different in different soils, the total nitrogen release range was 0.19-0.77 mg/L, the total phosphorus release range was 0.03-0.4 mg/L, and the ammoniacal nitrogen release range was 0.16-0.34 mg/L.

Mineral nutrient deficiencies in quinoa grown in hydroponics with single nutrient salt/acid/chelate sources

Major crop nutrient symptoms are well documented. In contrast, there is often minimal or no similar information for minor crops, including quinoa (Chenopodium quinoa Willd.). This knowledge gap can be efficiently filled by using hydroponic systems. However, creating multiple nutrient deficiencies with plants in the same study is challenging because nutrients are often added as dual nutrient salts. For example, if potassium sulfate is the potassium (K) source, varying K concentration also impacts sulfur (S) concentration, possibly creating dual deficiencies or other interactions. A new hydroponic system was created to impose nutrient deficiencies using single nutrient sources: ammonium nitrate; phosphoric, sulfuric, hydrochloric, and boric acids; potassium, calcium, magnesium, zinc, and copper carbonates; manganese acetate; sodium molybdate; iron EDDHA, with HEDTA as an additional chelate. Fourteen treatments were established including a positive control with nutrient concentrations anticipated to be optimal compared with individual deficiencies of nitrogen (N), phosphorous (P), K, S, calcium (Ca), magnesium (Mg), zinc (Zn), iron (Fe), manganese (Mn), copper (Cu), boron (B), molybdenum (Mo), and chloride (Cl). The “deficient” treatments were created by reducing concentrations by 80% for N and 90% for the others. The solution proved to be mostly effective as quinoa plants were grown to maturity. Stem size, plant height, and shoot and root biomass were impacted, especially for treatments with reduced N, P, and K. Unfortunately, the predicted adequate levels of some nutrients were likely excessive, especially B and Mn. Additional fine tuning is required to create a solution optimal in all nutrients.

Production of (R)-2-(4-hydroxyphenoxy) propionic acid by Beauveria bassiana ZJB16007 in solid state fermentation using rice bran

R-2-(4-hydroxyphenoxy)propionic acid (R-HPPA) is a key chiral intermediate for phenoxypropionic acid herbicide synthesis. In this study, to improve the production of R-HPPA with B. bassiana ZJB16007, the cultivation conditions in solid-state fermentation (SSF) were investigated. The effects of various substrates on R-HPPA production were evaluated and the process parameters were also optimized. The results showed that rice bran was the optimal substrate for R-HPPA production. The optimal medium components and cultivation conditions were: rice bran: silkworm chrysalis powder = 5.25: 2.25 (g: g), nutrient salts solution 12 mL which contained 50 g/L R-PPA, pH 5.0, and cultivated at 28 °C for 11 days. Under the optimized conditions, the transformation of R-HPPA was significantly improved and the yield of R-HPPA reached 77.78%, which was 15.14% higher than that of the control (67.55%). Therefore, SSF may serve as an alternative for R-HPPA production by B. bassiana ZJB16007.

BIOLOGICALLY ACTIVE COMPONENTS OF PEAT OF THE ARCTIC ZONE OF RUSSIAN FEDERATION

The deep processing of peat is one of the important resources for the development of the Northern Russia territories. The humic products are the most perspective from peat bio-active derivatives. At the same time, the presence of accompanying components with biological activity in them does not take into account. This research is focused on the elimination of this inaccuracy by studying the biological activity of fractions extracted from high-moor peat by the method of sequential disassembly. Bioactivity was characterized by the method of laboratory phytotesting on lettuce seeds, pretreated with solutions of preparations with stabilized pH and the content of nutrient salts. The performed studies confirmed the authors' hypothesis about the influence of the method of obtaining peat humic preparations on the biological activity. Antagonism of the effect on the phytoactivity of humic compounds, resins and waxes was revealed. The additional studies are required for an explanation of this mechanism. The fulvic acids stimulate seed germination, as part of the humic part, but intensify their damage by rot, while humic acids provide a smaller, but more stable, increase in germination due to the greater preservation of seedlings. Seed treatment with bituminous preparations inhibits the development of rot. The greatest fungicidal effect is shown by the fraction of resins, whereas peat wax, to a lesser extent, inhibits seed damage, but provides the highest and most stable stimulating effect in relation to their germination. Thus, peat bitumen waxes can serve as a good protective and stimulating agent and can be used, for example, to encapsulate seeds, as a presowing treatment to increase yields.

Effects of carbon to nitrogen ratio on the performance and stability of aerobic granular sludge

The purpose of this study was to assess the nutrient salts removal efficiency and stability of the aerobic granular sludge (AGS) by change in C/N (carbon to nitrogen) ratio. The laboratory-scale experiments were performed to analyze the removal efficiencies for organic matter and contents of nitrogen, MLSS, sludge volume index, and extracellular polymeric substances (EPS) under C/N ratio conditions of 5.0, 10.0, 15.0, and 20.0. The microorganisms were observed using optical microscope and the microbial communities were analyzed using pyrosequencing. The increase in C/N ratio from 5.0 to 20.0 increased the organic matter and nitrogen removal efficiency to 95.9 and 79.1%, respectively. For the EPS contents, an influencing factor of granule stability, the polysaccharides to protein (PS/PN) ratio increased from 0.55 to 0.79. For the microbial community, the <i>Thauera</i> was the most common genus in ending phase occupying 63.7%. This microorganism is regarded as one contributing to organic matter degradation and improved production of EPS including AGS of microorganism, thus, may be an explanation of the results of this study such as increase in organic material in AGS and improvement of denitrification efficiency and contents of EPS with increase in C/N ratio.

Microbial‐Induced Carbonate Precipitation for Strengthening Soft Clay

Currently, calcite produced in sediments by microbial‐induced carbonate precipitation (MICP) is mainly used as a strengthening binder in sand because sands are porous and have good permeability. Conventional wisdom does not consider MICP to be suitable for use in soft clay because of the clay particles’ small size and its minimal porosity. Because of the clay’s high water content and complex chemical composition, very little research has been done and not much is known about the use of MICP in soft clay for strength enhancement. For this paper, soft clay specimens were prepared by mixing a solution containing Sporosarcina pasteurii bacteria, solutions with different concentrations of nutrient salts, and soft clay. Unconfined compressive strength tests were carried out on these specimens after they had cured for 28 days in a moisture‐controlled environment. These laboratory tests were used to study the chemical reactions, the clay’s strength, and other influencing factors. The results are as follows: (1) directly mixing a S. pasteurii solution, nutrient salts, and soft clay considerably improves the uniformity of the spatial distribution of the bacteria and the nutrients in the soft clay. Directly mixing these constituents promotes the formation of calcium carbonate and greatly simplifies soft clay sample preparation. (2) It is feasible to use MICP to increase the strength of soft clay. Compared to control specimens cured under the same conditions but without introduced nutrients and bacteria solution, the unconfined compressive strength of MICP‐treated specimens can be increased by as much as 2.42 times to an unconfined compressive strength of 43.31 kPa. The water content in MICP‐treated specimens was significantly reduced by the MICP reactions and in one case decreased from 40% to 30.73%. (3) The strength enhancement of microbially solidified soft clay is the result of two processes: urea hydration catalyzed by enzymes consumes water in the clay and the bacterially precipitated calcite forms in the sediment’s pores. (4) The micro‐organism‐produced calcite in the soft clay increases the calcite abundance from 0% to as much as 3.5%. (5) The MICP‐treated strength of soft clay varies with the concentration of the nutrients provided. For the experimental conditions used for this paper, the optimum concentration of the CaCl2·2H2O and CH4N2O nutrients is 0.5 mol/L.

Field Assessment of Influence of Organic Fertilizers on Microbial Profile and Sustainable Maize Production in a Flood Plain in Nigeria

The stabilization and utilization of organic fertilizers in flood plain for sustainable agriculture in the tropics was studied in field experiment conducted at Etinan wetland soil (EW) of Akwa Ibom State, Nigeria in the tropics during two cropping seasons (C. S.) to study the effects of two composted and stabilized organic fertilizers (poultry droppings, PD and cow dung, CD) on the microbial density and structure, soil properties, growth and yield of corn (<i>Zea mays</i>) according to standard procedures. The two treatments plus control, (the unfertilized plots) were arranged in a randomized block design with two replications giving three main plots; poultry manured plots (PM), cow manured plots (CM) and the control plots, C, which were sectioned into nine subplots on which was a total of 81 mounds on the study site. Results showed that PD and CD (450 gm²=4500 kgha^-1) incorporated into the EW produced higher mean microbial density (Total heterotrophic bacterial counts, THBC=log 7.636 and 8.64, total actinomycetes counts, TAC=log 6.57& 6.62, diazotrophic bacterial counts, DBC=log 5.35 & 5.50 and total fungal counts, TFC=log 5.38 & 5.45 cfug^-1) in both fertilized plots during the 1st & 2nd C. S respectively than in the control with 6.62 & 7.49, 5.59 & 5.52, 5.44 & 5.54, 4.5 & 5.49 cfug^-1 of THBC, TAC, DBC and TFC respectively. It was also shown that PD and CD application into EW produced higher physicochemical properties, nutrient salts, compared to the C. Growth/yield of the test crop, <i>Zea mays</i> were increased in the PM followed by CM compared to C in the EW during both C. S. Using the mean difference of two years, plants of PM had highest grain yield (4.16±0.16t t/acre) compared to (2.84±0.31t/acre) and (0.09±0.23t/acre) of CM and C respectively. The effects of one time application of the organic fertilizers (without reapplication on the 2nd C. S) indicated higher crop harvest index, H. I. (0.63 and 0.64) of treatment plots compared to 0.19 and 0.20 of the C. Therefore, utilization of PM to soils is recommended for sustainable crop production especially maize in the flood plain and in the tropics as a whole. It is also recommended that the CD could serve as a suitable substitute in the absence of PD. Wetland soils in the tropics should be converted from the hitherto wasteland to useful and sustainable arable lands with the utilization of stabilized and composted organic fertilizers.

Histopathological alterations and parasitic infection in Oreochromis niloticus fish inhabiting the River Nile water.

Histological and parasitic examinations represent an excellent tool for determining the effect of Nile water contamination on fish health status. This paper outlines the effect of sewage, industrial and agricultural drainage water into six selected sites (El-Kanater El-Khyria, El-Qatta, Tamalay, Kafr El-Zayat, Benha and Talkha) at River Nile branches on Oreochromis niloticus fish. Water samples were collected from the investigated area during winter 2019 to assess the status of water by determining some physicochemical characteristics (temperature, electrical conductivity, transparency, pH, oxygen and nutrient salts). Also, histological features for some organs (liver, kidney, and gills) and parasitic infestation in fish were studied. The results revealed that the uncontrolled inputs of wastes altered the water quality of investigated areas leads to the prevalence of the most common parasites genera which infected Oreochromis niloticus health status in the form of histological alteration.

Water quality affected by floating debris near the dam section of Three Gorges Reservoir

每年汛期与蓄水期三峡水库近坝段水域会有大量漂浮物聚集，为探索三峡水库近坝段水域（坝前及以上约12.7 km长的河段）水面漂浮物对水质的影响，2018年开展了漂浮物覆盖水体水质跟踪监测和漂浮物浸泡试验，并以2014-2018年的漂浮物产量和近坝段水域水质监测数据为基础进行了相关分析与回归分析.结果表明：漂浮物会提高坝前覆盖水体的氮类营养盐水平和有机污染物浓度，引起河湾漂浮物覆盖水域氨氮（NH₃-N）浓度升高，致使氮类营养盐组成的变化和由于高锰酸盐指数/总有机碳比值（COD_Mn/TOC）的差异变化对水体产生有机污染.除NH₃-N外，坝前水域受漂浮物影响程度大于河湾区域，漂浮物对河湾水质的影响在蓄水期更为明显，漂浮物覆盖水体垂直方向上2 m内水质因子无明显分层现象；相比综合类漂浮物，植物类漂浮物对水质的影响更迅速和明显；漂浮物仅在其覆盖的水体小范围内对氮类营养盐指标造成影响，漂浮物产量的增加会增大近坝段水域水体悬浮物、有机污染物和还原性无机物质（COD_Mn）浓度，形成一定的影响规律.因此，合理布置清漂作业点，高效及时地开展漂浮物清理工作，短期内优先打捞植物类漂浮物，合理实施水库调度以减少漂浮物聚集量与缩短滞留时长，加强漂浮物影响水体的水质监测对近坝区河段水环境保护意义重大.;During the flood season and impoundment period, there will be a large amount of floating debris gathering in the water area near the dam of the Three Gorges Reservoir. In order to explore the influence of water surface floating debris on the water quality near the dam section of the Three Gorges Reservoir (about 12.7 km long before and after the dam), floating immersion test and water quality monitoring of floating body covered water were carried out in 2018. Correlation analysis and regression analysis were used to analyze both the drift production of 2014-2018 and the water quality monitoring data of the near dam section. The results showed that the floating debris increased the concentration of nitrogen nutrient salts and organic pollutants in front of the dam, and led to the increase of NH₃-N concentration in the bay area resulting in the change of nitrogen nutrients composition and organic pollutants pollution due to the difference of COD_Mn/TOC ratio. In addition to NH₃-N, the influence of floating debris on the water quality in front of the dam was greater than that in the bay area. For the bay area, this influence became more obvious during the impoundment period. There was no obvious stratification of water quality factors within 2 m in the vertical direction of the water body covered by floating debris. Comparing to the comprehensive floating debris, the effect of plant floating debris on water quality was more rapid and obvious. The floating debris only affected the nitrogen nutrient index within a small range of water covered by it. The increase of floating debris production led to the concentration increase of suspended matter, organic pollutants and reducing inorganic substances (COD_Mn) in the water near the dam, forming a certain influence law. Therefore, it is of great significance for water environment protection to arrange the floating debris cleaning operation points reasonably, to carry out floating debris cleaning efficiently and timely, to give priority to the salvage of plant floating debris in a short period time, to implement reservoir scheduling reasonably in order to slow down the accumulation and retention time of floating debris, to enhance the monitoring about the impact of floating debris on water quality near the dam.

The Effect of ENSO on Hydrological Structure and Environment in the South Central Coast – Vietnam

ENSO (El Niño-Southern Oscillation) phenomena have impacted on the hydrodynamic regime and environmental factors of the tropical ocean in general. In case of Vietnamese South-Central Waters, impacts of ENSO only focused on issues of changing seasonal wind, seawater temperature anomalies, changing of water masses as the air-sea interaction. Based on several data sets collecting in the period of 2003-2017, new finding of seawater temperature, salinity and environmental factors was identified in the water masses of Vietnamese South-Central Waters. The highest salinity was 35.4 ‰. During the El Nino event, increasing water temperature and salinity caused to move the deeper water masses to be closer to the sea surface than that initial depth in the neutral period. During the La Nina event, the temperature of most water masses reduced by 0.1-3°C, and then these water masses could be affected to the deeper layer. During the phase from strong ENSO event towards the neutral time, nutrient salts of the 4 water masses were lower concentration in the neutral year, causing the lack of phosphorus in sea surface water masses.

Sustainable and Effective Chitosan Production by Dimorphic Fungus Mucor rouxii via Replacing Yeast Extract with Fungal Extract

The effects of switching morphology and replacing supplementary nutrients with fungal extract (5 and 10g/L) on the production of major metabolites and chitosan by Mucor rouxii were investigated. This approach was supposed to promote sustainability of the fermentation process and improve its economic feasibility. Different fungal morphologies, i.e., purely filamentous (PF), purely yeast-like (PY), mostly filamentous (MF), and mostly yeast-like (MY), were evaluated. The highest ethanol yields were obtained from the media supplemented with 10g/L fungal extract for all morphologies, while adding nutrient salts did not make any improvements in these yields, except a slight decrease in the fermentation time. Except for PF morphology, the replacement of yeast extract favored the biomass production yields. Moreover, the alkali insoluble material (AIM) yields were higher as a result of the replacement for most cases. Furthermore, the replacement resulted in increased glucosamine and decreased N-acetyl-glucosamine content of AIM for almost all the morphologies. AIM yields of at least 0.25g/g-glucose and maximum chitin/chitosan yield of 0.78g/g-AIM were obtained from the solids remaining after autolysis process, which were higher than that obtained from the raw biomass. The maximum yield of 0.135g/g-AIM purified chitosan with intact molecular weight was obtained from the biomass with PF morphology supplemented with 10g/L fungal extract plus nutrients.

Spatial Distribution Characteristics of Chlorophyll-a and Nutrient Salts in Tributaries of Different River Sections in the Three Gorges Reservoir Area During the Flood Season

The construction of the Three Gorges Reservoir has had certain effects on the ecological environment of the water and serious phytoplankton blooms have occurred in its tributary embayment. To explore the spatial distribution of nitrogen and phosphorus nutrients and chlorophyll-a in different tributaries of the Three Gorges Reservoir, a water quality study (June 2018) was conducted in the Xiangxi River, Shengnongxi River, and Daning River of the Three Gorges Reservoir. The results showed that the average TN in the three tributaries was 1.86 mg·L-1, 1.90 mg·L-1, and 1.43 mg·L-1, respectively, and average TP was 0.09 mg·L-1, 0.07 mg·L-1, and 0.05 mg·L-1, respectively. Single-factor ANOVA analysis showed that the spatial difference in TN was significant and occurred in the following order:Shennongxi River > Xiangxi River > Daning River. There were significant differences in the spatial distribution of TP, which were in the order off Xiangxi River > Shennongxi River > Daning River. The mean concentrations of chlorophyll-a in the three tributaries was 6.41 μg·L-1, 21.39 μg·L-1, and 9.85μg·L-1, respectively. The results from the Pearson correlation analysis, showed that chlorophyll-a concentrations were closely related to TP distribution in all tributaries, but Zeu/Zmix was also correlated with the distribution of chlorophyll-a in the Shennongxi River and Daning River. The ratio of TN and TP concentrations was 22.36, 26.76, and 28.6, respectively, which revealed that TP is a critical and limiting factor affecting phytoplankton growth in its tributary embayment.

The First Steps in Examining of Carbon Absorption and Nutrient Salt Filtering Capability of Rhodomelaceae Laurencia Papillosa Seaweed over Some Typical Island Communes in Vietnam Coastal Area

Viet Hai is a commune in Cat Hai district, Hai Phong City. The commune is located in the East of Cat Ba island which is the third largest island in Vietnam. Nhon Chau is also an island commune which is located in Quy Nhon city, Binh Dinh province. Nam Du commune is one of four island communes of Kien Hai district, Kien Giang province, and located at 120 kilometers away from the Rach Gia city. The results showed that the averaged values of nutrients absorbed by Rhodomelaceae Laurencia Papillosa in 12 hours were 1.39µg/l/day (N-NO2-); 11.74µg/l/day (N-NO3-); 24.08µg/l/day (N-NH4+); and 7.83µg/l/day (P-PO43-) in Viet Hai commune. In Nhon Chau island commune, the averaged values of nutrients absorbed in 12 hours were 1.25µg/l/day (N-NO2-); 7.44µg/l/day (N-NO3-); 11.81µg/l/day (N-NH4+); 23.53µg/l/day (P-PO43-), respectively. In Nam Du island commune, the nutrients absorbed in 12 hours reached the values of 23.4µg/l/day (N-NO2-); 15.3µg/l/day (N-NO3-); 101.65µg/l/day (N-NH4+); 30.32µg/l/day (P-PO43-), respectively. The average values of carbon absorbed by seaweed biomass in Viet Hai, Nhon Chau, and Nam Du communes were 30.27mgC/m2/h, 31.31mgC/m2/h, 33.00mgC/m2/h, respectively.