جستجوی مقالات مرتبط با کلیدواژه « مواد مغذی » در نشریات گروه « شیلات »

Nutrients in wastewater enrich the environment and cause environmental problems in aquatic environments. Conventional wastewater treatment systems are not capable of removing phosphorus effectively.  The  entry  of  phosphorus  into  water  resources  leads  to  the  formation  of  an Eutrophication  phenomenon. Micro-algae have been more effective among the various methods used for the removing of nutrients from wastewater. Wastewater biological-treatment using algae to eliminate nitrogen and phosphor and produce oxygen for aerobic bacteria is a new trend that has drawn a great deal of attention. Using sunlight, microalgae consume nutrients in wastewater and convert them into useful biomasses. Wastewater biological-treatment using microalgae was studied. Treatment efficiency of micro-algae depends on the species, algae mass concentration, aeration level, and the optimal time to maximize algae activity on wastewater.

Searching, identifying, and ultimately using important and valuable bioactive compounds is one of the main goals for the principled management and sustainable development of the fisheries industry. Nowadays, fisheries and aquaculture have a very special role in the economy and providing sustainable healthy dietaries and the development of new drugs to establishment human health and aquatics are a rich source of proteins, essential amino acids, fatty acids (saturated fatty acids, monounsaturated fatty acids, polyunsaturated fatty acids (omega-3 and omega-6)), carbohydrates, vitamins and minerals. On the other hand, in today's world, a large amount of the by-catch of fisheries or aquatics processing industries is thrown away and causes many environmental problems. Considering the nutritional value and the presence of bioactive compounds in by-products from aquatics, these organisms can be used as a rich source of these compounds. The results of this study showed that bioactive compounds extracted from aquatics, play an important role in dietary, increasing health, and prevention and treatment of various diseases in humans. These compounds contain valuable resources such as peptides and protein hydrolysates, polyunsaturated fatty acids, collagen and gelatin, polysaccharides, chitin and chitosan, glycosaminoglycans, carotenoids, phenolic compounds, rare elements and other natural compounds with antioxidant, antimicrobial, antiviral, anticancer, anti-inflammatory, antidiabetic, anticoagulant, antihypertensive, antiaging, heart protective, neuroprotective and immune-modulating potentials. According to this, they have found many applications in the nutrient-pharmaceutical (nutraceutical), medical, agriculture, biotechnology, cosmetic industries, and other industries due to their specific functional potential. The purpose of this study is to review the importance of functional and health-giving properties of bioactive compounds extracted from aquatics.

The object of this study was to investigate the status of physicochemical parameters and nutrients in demersal fishing grounds in the Iranian waters of the Persian Gulf from the Hormozgan province to Khuzestan province, from autumn and winter of 2017 to 2020. The local data of physical and chemical parameters of water were recorded and analyzed, by using a CTD (Conductivity, Temperature, and Depth)  device, during 2017, 2018 and 2020 years. Also, the sea surface temperature and chlorophyll-a were recorded from the MODIS (Moderate Resolution Imaging Spectroradiometer) satellite, aqua sensor, in 2018 and 2019 years. The average of remote sensing data of sea surface temperature and chlorophyll-a were 22.83 C° and 1.80 mg.m-3, respectively in the studied area, from 2018 to 2020. The average of local data of water temperature, chlorophyll-a, salinity and pH were 21.53 °C, 0.84 mg.m-3, 39.53 ppt and 8.28, respectively in the studied area during the years 2017, 2018 until 2021 winter. The average of concentrations of nitrate, phosphate and silicate were 0.034, 0.008 and 0.517 mg/L, respectively, in the present study. Based on the results, the amount of chlorophyll in the Persian Gulf has a relationship with the sea surface temperature and silicate. By increasing the sea surface temperature and concentration of silicate, the chlorophyll-a increases in the studied area. Changes in the concentrations of nitrate and phosphate had no significant effect on the concentration of chlorophyll-a in the studied area. The average of sea surface temperature and the concentrations of phosphate and silicate increased, but the concentration of chlorophyll-a and nitrite decreased from 2018 autumn to 2020 winter.

Nowadays, one of main environmental problems of the aquaculture wastewaters is the presence of nutrients and heavy metals in these sources. The aim of this study was to investigate the phytoremediation potential of the Common duckweed (Lemna minor) in reducing nitrate, phosphate, cadmium and lead from aquaculture wastewater and determining the inhibitory effect of cadmium and lead on the growth of this species. For this experiment, L. minor were collected from the margins of the wetlands and transferred to the laboratory and were treated by four experimental groups in triplicate. At the end of the 15-day experimental period, the concentrations of heavy metals cadmium, lead, nitrate and phosphate in the treatments were examined. Increasing L. minor surface coverage decreased cadmium, lead, nitrate and phosphate concentration in the treatments. The study also showed that both lead and cadmium reduced the growth factors of L. minor. So that increasing the amount of lead by 20 mg /l reduced the growth of L. minor by 84.11% and also cadmium by 30 mg /l reduced the growth of L. minor by 82.1%. Finally, according to the results, it can be concluded that the L. minor is a valuable species for phytoremediation purposes.

In this study, the ability of Spirulina platensis microalgae in dairy wastewater treatment and nutrient removal associated with biomass production was evaluated. Therefore, two concentrations of Spirulina platensis (0/05 and 0/1 g/L) were cultured in three dilutions (25, 50, 75%) of dairy wastewater and the efficiency of nutrient removal and biomass production was evaluated with six treatments in three replications. Nutrient and biomass values ​​were measured on every other day. The results showed that both factors of different concentrations of algae and different dilutions of wastewater had an important role in nutrient absorption and biomass production. The highest percentages of nitrate, phosphate, ammonia removal (99/85, 82/60, 99/83%) and maximum amount of biomass (1/690±0/01 g/l) in 25% dilution and concentration of 0/1 g/l microalgae was obtained. In this research, by decreasing percentage of dilution of dairy industry wastewater and increasing amount of nutrients available in microalgae and also by increasing the initial concentration of injectable microalgae in the wastewater, more nutrients were removed, and the nitrate and ammonia levels were almost 100% eliminated and the amount of biomass increased. As a result, according to the results, Spirulina platensis microalgae has a high performance in removing nutrients (nitrate, phosphate, ammonia) from dairy industry wastewater and can be considered for dairy industry wastewater treatment.

In this study, surficial sediments along 9 stations (from Bilqan to Dizin and Varangeh_e Rood) were collected seasonally along 2017-2018 and water quality was assessed using enrichment index (EF) and Pollution load index (PLI).The percentages of sand, silt, clay in the sediment samples were determined (78, 17 and 5 respectively). The mean of Al, As, Cu, Fe, Ni, Pb, Cr, Zn, V, TP and TN in the sediment samples were 7.35±1.99%, 8.0±1.2 ppm, 41.0±30.2ppm, 3.56±0.53% , 24.33±4.87 ppm, 5.9-13.6 ppm and 21.8-28.8 ppm, 15.9±5.99 ppm, 36.08±11.45 ppm , 68.08±08.6 ppm, 88.9±23.3 ppm, 0.1±0.05% and 0.42±0.07% respectively. Based on cluster analysis, Asara and Shahrestanak (group1); Pool-e Khab and Gachsar(group2), Bilqhan, Varangh_e Rood, Hassankader and Dizin (group3); and Pool_e Choobi (group4) categorized into separate groups. In general, the concentration of nutrients and heavy metals in the stations did not exceed the PEL and SEL. The enrichment index for both chromium (0.2) and iron (0.8) showed a degree of non-enrichment at all stations. Other metals showed a low degree of enrichment and have low enrichment levels and, in terms of arsenic concentration, EF have been moderate to severe (4.9±1.1). According to the PLI index (1.35-1.9), all stations were more than one, so it can be concluded that all of them were polluted.

The monitoring of the harmful bloom of Cochlodinium polykrikoides in the northern Persian Gulf was studied during 2010 to 2011. The results revealed that in the waters of Hormozgan Province, the Diatoms and Dinoflgellates had the highest frequency. No significant difference was found for amount of nutrients in three sub- regions. The bloom of C. polykrikoides was higher in central sub-region in spring and was occurred in the eastern sub-region in summer, but no mortality of fishes was recorded. In Bushehr Province, four classes of Bacillaryophyceae, Cyanophyceae, Dynophyceae and Prymnesiophyceae were determined. Furthermore significant different values of nutrients were recorded. In waters of Khuzestan Province, different values of NH4 were measured for different months. In total, the measured ratio of N: P in all months were lower than Redfield Ratio (16:1) in which subsequently the environmental condition was not suitable for bloom of C. polykrikoides.