جستجوی مقالات مرتبط با کلیدواژه « sediment » در نشریات گروه « شیلات »

This study examines the characteristic of microplastics (MPs) in sediments collected from the coastal areas of the southern Caspian Sea, Mazandaran province (Babolsar and Sari cities). Twelve sites for sediment sampling selected during 2022. MPs identification detected primarily under stereomicroscope and then ascertains and discovers their polymer composition by ATR-FTIR. The results showed that Babolsar areas, with 5 meters far from the shoreline, had the most abundance (660±165.15items/Kg). On the other hand, Sari station with 500 meters far from the shoreline contained the least MPs (220±81.33). Average number of detected MPs in all samples was 406.66±161.33. Fibers (80.33%) were the most abundant MPs, whereas films (3.28%) detected the least. In the case of size, the range of 1000-3000µm showed the most abundant MPs (39.34%) and MPs less than 2 µm the least ones (4.10%). Gray and black (50.82%) was the dominant color and yellow (3.28%) was rarely detected color (3.28%). Polymer constituent of examined MPs includes: (PET: 30%); (PS: 20%); (PA: 20%); and (PP: 15%). The findings of this study revealed that MPs occurrence in coastal sediments distribute from several sources; including tourism as well as wastewaters and packaging. These activities cause entering plastic litters along the coastal areas and their degradation accelerated t MPs distribution.

Rivers efficiently transfer microplastics into seas, meanwhile they can be temporarily stored in sediments, where they undergo further fragmentation due to biological and physical processes. This study was conducted with the aim of investigating the distribution and abundance of microplastics (MPs) in the surface sediments of Khormarud River, Golestan province, Iran. A total of 15 sediment samples (5 stations with 3 replicates) were taken in the spring of 2022 and the identification of MP was studied using a stereomicroscope. Their polymer compositions were characterized using weak total reflectance Fourier transform infrared spectrometer. The results showed that station 5, with high human activities, had the highest frequency of MPs with 880±160 particle/kg of dry sediments, and station 1, upstream of the river, had the lowest frequency with 200±66 particle/kg. The average of MPs observed in all studied stations was 430.17 ± 92.8 particles. The most abundant MPs were fiber (77.52%) and the least abundant were films (3.10%). The results showed that the 500-1000 µm group had the highest frequency with 44.19%, while the 3000-5000 µm group had the lowest frequency with 3.88%. Black color was the most frequent with 55.81% and blue color was the least frequent with 2.33%. The polymer composition of MPs includes polypropylene (PP, 41%), polyethylene (PE, 30%), polystyrene (PS, 16%), polyester (PS, 11%), and polyamide (PA, 2%). The results of this study showed that MPs in coastal sediments have a complex source that is mostly derived from tourism, sewage, and packaging.

The Caspian Sea is a unique brackish system in terms of water salinity, so evaluation of pollution criteria based on the water quality of the same sea is past and present. In this study, information was collected from 2008 to 2010 and analyzed during the project during these years, sampling of eight transects shorelines was performed seasonally at stations 10, 20, 50 and 100 m of depth in two summer and winter seasons for water and sediment. The results showed that the concentration of organochlorine toxins in the aquatic environment depends on its entry through the rivers leading to it and its concentration in water varies in different seasons and regions. The results showed that the concentration of organochlorine pesticides in the aquatic environment increased in winter of 2008 with the highest percentage of pesticides in spring, summer, autumn and winter in middle, middle, east and west and maximum percentages, respectively. Toxins were found in the water samples of the eastern part of the region by 75% in spring. Also the maximum concentration of organochlorine toxin belonged to α-Endosulfan toxin with a concentration of 3.86μg/l which was recorded in Nowshahr at 50 m depth of surface water. Conclusion In the current situation, the concentration of chlorine toxin compounds in the appropriate range and distance from the shore of water quality conditions is more suitable for fish farming in cages. Therefore, it is suggested to consider the establishment of fish cage culture at 50 m of depth.

The Incheh wetland, with high ecological importance, is located in the north of Aq-Qala (Golestan province). In this study, the surface sediments of the Incheh wetland from 7 stations with a maximum depth of 2.8 m were collected in November 2018 to find the source and determine the amount of heavy metals pollutions in the wetland and calculate the indices of enrichment factor and pollution load. The water environmental parameters, heavy metals, grain size, and total organic matter were measured by portable multi-parameter meter, inductively-coupled plasma mass spectrometry, laser diffraction particle size analyzer, and oven combustion, respectively. The mean of Al and Fe in the sediments were 0.8±0.4 and 1.5±0.6%. Also, the mean of As, Cu, Ni, Pb, Cr, Zn and V in the samples were measured 2.8±4.6, 12.8±3.6, 26.7±6.4, 7.0±2.7, 25.7±7.8, 32.4±16.2 and 28.6±7.1 mg/kg, respectively. In general, in terms of the enrichment factor index, the wetland has low enrichment (1-1.8). In the case that station 5, in terms of Fe (3.7) and As (5.7) had moderate enrichment and moderate to severe enrichment, respectively. In terms of the range of pollution load index (0.46-0.84), all stations were less than 1, so they were not polluted. In general, due to the fact that the amount of nickel and arsenic in all stations and station 5 was higher than the TEL, respectively, it can be concluded that the probability of severe biological effects on most of benthic organisms is low and at the threshold level.

The presence of microplastics (less than 5 mm) in marine environments, owing to their persistence and risk imposed to marine communities has become a growing global concern. Considering the hazardous nature of microplastic particles to benthic communities and commercial species of the Caspian Sea, the study was conducted to investigate the distribution of microplastics in sediments of the southern shores of the Caspian Sea. Sediment samples were taken by a Van Ween grab as sampling sites located in Astara, Bandar Anzali, Kiashahr, Rudsar, Sari and Turkmen port during the winter 2018. Sari station with an average of (340±20 items/kg dry sediment) had the highest and Turkmen port station with (156.66±75.71 items/kg dry sediment) had the lowest microplastic frequency. The size of the microplastics varied from 0.2-9.2 mm and most of the microplastics found (35.54%) were 1-2 mm in size. The extracted microplastics were mainly filamentous although fragment microplastics and films were also observed. In the studied samples, high color diversity was observed and blue (63.85%) and brown (20.31%) had the highest frequency. Using ATR-FTIR analysis, 4 types of polymers including cellophane, polyethylene, polypropylene and polyvinyl acetate were identified. The most abundant microplastics identified were cellophane. This study is among very few studies on microplastic contamination in the sediments of the southern Caspian Sea and the obtained results vital for further studies.

In this study, coastal sediments of Qeshm, Bandar Khamir and Bandar Laft regions in Hormozgan province were studied to determine the level of contamination of heavy metals lead, nickel, zinc, iron and copper by natural processes or human activities. In order to identify environmental pollutants caused by heavy metals, shovel sampling was performed from the sediments of these areas to measure the concentration of heavy metals and determine the enrichment index. The location of the samples was determined using a GPS device and sampling of surface sediments (tidal zone) was performed at 30 stations in the study areas. Atomic absorption of flame spectrometry was used to determine the concentration of heavy metals. The results showed that the mean concentrations of heavy elements lead, nickel, zinc, iron and copper in all sampling stations showed a significant difference (p<0.05). In terms of concentration of studied elements in Qeshm region (copper: 33.76 ± 1.88, zinc: 85.44 ± 2.75, lead: 31.79±  1.23, nickel: 34.17 ± 2.29 and Iron: 38000±691.21 μg/g) compared to Bandar Khamir (copper: 26.84 ± 2.30, zinc: 77.54 ± 2.12, lead: 24.71±  1.37, nickel:25.82± 1.30 and iron: 36810± 482.882 μg/g) and Bandar Laft (copper: 22.74± 2.42, zinc: 65.22±2.61, lead: 19.93± 1.32, nickel: 21.70±2.06 and iron: 35560±1014.56 μg/g) had higher contamination. The results also showed that the metal enrichment factor is low in all sediment samples and in terms of Müller geochemical index, the degree of soil contamination is in the category of non-contaminated soils.

Investigating the quantitative and qualitative characteristics of resources is one of the key pillars of sustainable development and sound management practices in various fields of environment, fisheries and agriculture. The impact of pollutants on organisms varies according to their type and volume of input. These effects at the highest levels cause the destruction of the fauna and flora of the area and in small amounts eliminate the resistant species. In recent years large-scale invertebrates inhabit sediments reflecting the effects of environmental contamination as a change in their diversity or density, which is why more attention has been paid to biological monitoring studies. In each half-line, sediment samples were taken from the surface layer at 3 different depths of 5, 10, 15 m. Sediment samples were analyzed by ICP-OES (Varian Vista -MPX model) according to ASTM D5258-92, 2013. Shannon Wiener Index, Species Richness Index and Margalef Index were used to assess the Diversity, Dominance and Richness of Macrobentic in the study area. On average, the lowest Shannon Wiener Index of Fereidonkenar Port in spring (0.63), in Summer (0.25), in Autumn (0.54), in Winter (0.37). The lowest Margalev Index of Fereidonkenar Port in Spring (0.45), in Summer (0.25), in Autumn (0.46), in Winter (0.28) was achieved. In the present study, were significantly  higher (p<0.05) compared to Shannon and Margalph Index. Also, the result  shown were different temporal and spatial variations in the structure of Benthic Communities and  stress and contamination were moderate.

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.

This study was designed to determine the sediment structure, Total Organic Matter (TOM) and facultative anaerobic bacteria communities of sediment affected by cage culture of rainbow trout in the coastal waters of Abbas Abad area (southern basin of the Caspian Sea). For this purpose, sediment samples were collected at distance of 5, 50, 100 and 1000 m from the cages in December 2014 (before the culture period), March and April (production period) and August 2015 (after the culture period). Determination of sediment grading showed that its structure was composed of silt-clay (91.7%) and very fine sand (6.44%) and the sediment structure was not affected by the cage culture. The Total Organic Matter was significantly different only between the sampling periods (P<0.05) so that the highest amount of Total Organic Matter (TOM) was observed during the production period whereas, it was not affected by the distance from the cages (P<0.05). It seems that the rainbow trout cage culture in the Abbas Abad region no remarkable effect on the factors studied in the vicinity of small scale fish cages due to the short duration of cage culture and strong water currents, so that observed changes were more associated with seasonal fluctuant.

The following research was conducted to study the concentration of Ni and Cd in skeletons and sediments of dominant hard coral family and Poritidae in Zeyton Park, Naz Islands and Shibderaz stations, South of Qeshm Island Persian Gulf. The analysis of these heavy metals in digested samples of skeletons and sediments was done applying Graphite furnace Atomic Absorbtion Spectophotometry SHIMADZU, AA 670 for measuring the levels of Cd and Flame Atomic Absorbtion Spectophotometry SHIMADZU, AA 670 for measuring the levels of Ni.The concentration of Ni in skeleton of coral family Poritidae in Shib-deraz station 29/95, in Naz Islands 27/94 in Zeyton Park 26/16 and the concentration of Ni in sediments of coral in Zeyton Park station 27/91 in Naz Islands station 25/70 and in Shib-deraz station 25/50.The results indicated that there are significant statistical differences toward concentration of Ni in skeleton of coral family Poritidae among Zeyton Park, Naz Islands Shib-deraz stations (P<0.001). But Cd concentration is not significant (P=./992) In addition, considering the concentration of Ni and Cd in sediments of coral familie Poritidae there are significant differences (P<0.05 and P<0.001 respectively). Long term pollution monitoring by heavy metals is of great importance in managing coastal areas. So, concerning the immense importance of coral ecosystem in southern Qeshm Islands and the result of this research, corals can be suggested as a pollution biomonitor