جستجوی مقالات مرتبط با کلیدواژه « plastic » در نشریات گروه « کشاورزی »

As one of the most important food producers, the agricultural industry consumes a lot of energy to produce various products. Also, agriculture is the largest supplier of energy in the form of biological energy. This study was conducted in Khuzestan province with the aim of investigating the energy indicators of okra and the contribution of different inputs to the total energy in monoculture, intercropping (okra+cucumber) and agroforestry (okra+date palm) systems. The simple random sampling method was used to determine the survey volume and calculated sample size in this study was found to be 139. The data used in the study were collected from okra farms using a face-to-face questionnaire. The inputs and outputs were calculated per hectare and then, these input and output data were multiplied by the coefficient of energy equivalent. Following the calculation of energy input and output values, the energy ratio, energy productivity and net energy were determined. The results indicated that averages of energy inputs in monoculture, intercropping and agroforestry systems of okra were 78763.77, 81269.27 and 52502.42 respectively, while the energy output in these systems was 17575, 37380 and 113715 MJ ha-1, respectively. The energy ratio in monoculture, intercropping and agroforestry systems were calculated as 0.223, 0.460 and 2.166 respectively. The energy productivity in intercropping system was calculated as 0.470 kg MJ-1, which was about 302% and 64% more than monoculture and agroforestry, respectively. This issue is due to the higher yield of this cultivation system compared to other investigated systems.

Atmospheric precipitation is one of the most important sources providing water for various purposes. Their optimal use, especially snow and rain in arid and semi-arid regions, can play a significant role in meeting water needs in low water seasons, which can be collected and stored before they come into contact with the soil surface and become contaminated so that in times of water shortage, To provide the water needs of industries and factories, green spaces and drinking water for humans and animals. One of the methods of harvesting water from precipitation, including snow and rain, is to make the surface of the earth impermeable and maximize the runoff caused by them. Impermeable surfaces can exist naturally like stone surfaces or by covering the ground surface with materials such as asphalt, concrete, and insulation sheets such as plastic, geomembrane and decamond can be created artificially. In this research, 2 treatments with 3 repetitions were considered, which included the Catchment of geomembrane cover and plastic cover with sand protection, each in a square shape with an area of 4 m2, and were implemented in lands with an average slope of 36%. The total rainfall on the mentioned surfaces during the statistical collection period was 747 mm, of which 430 mm (52 events) was in the form of rain and 317 mm (26 events) was in the form of snow. The results of 26 winter snowfall events during two years of statistics showed that the runoff from normal precipitation in winter for geomembrane and plastic covering with sand protection is equal to 89 and 80% of precipitation, respectively. Therefore, according to the normal rainfall of the winter season (65.4 mm), the volume of runoff collected for the geomembrane cover and the plastic cover with sand protection will be 58.2 and 52.3 lit m-2, respectively in the winter season, if from the short-term statistics. The statistical period should be used, according to the annual rainfall (373.5 mm) and the winter season (158.5 mm), the volume of runoff collected in the winter season for the catchment surfaces covered with geomembrane and plastic cover with sand protection reaches to 141 and 127 lit m-2, respectively.

Wastewater treatment plants are known as an important source of microplastics. Though a major proportion of microplastics are removed in wastewater treatment plants, the effluent of plants contain a significant amount of microplastic particles which eventually release into the environment. Until now there is no investigation on the role of wastewater treatment plants on the release of microplastics in Tehran. This study aims to assess the discharge amount of microplastic particles from wastewater treatment plant in district 22 of Tehran. Sampling was conducted from the influent and effluent of the plant with grab method and sieving through 300, 105 and 25 µm stainless still filters.  Retained samples were treated to remove organic and inorganic materials. Then particles were detected, counted and analyzed under microscope (*10). Results indicate that treatment process has a significant impact on microplastic particles removal. After the treatment process, the average of 2.15 MP/liter were found in the effluent. Larger particles were removed effectively (at the size of ≥300 and 105-300 µm) and smaller particles (25-105 µm) indicated a higher abundance. Among the detected particles fibers had the highest abundance and then fragment were at the second order. This finding indicates that waste water treatment plants can act as a source for microplastic pollution in the urban environment.

Microplastics are plastic particles smaller than 5 mm that are known as emerging contaminants. Most research about microplastics has been performed in aquatic ecosystems and there is limited information about the effects of these particles on soil biological and enzymatic properties. Therefore, the aim of this research was to evaluate the effect of Microplastic particles on some soil properties included basal and cumulative respiration, microbial biomass carbon as well as soil acid and alkaline phosphatase activity. For this purpose, Low-density polyethylene (LDPE) microplastic particles (diameter 0.5 - 1 mm) added to the soil (1, 2 and 4 % w/w). Incubation times for investigation of soil properties and enzymes activity were 87 and 45 days, respectively. The results showed that the microplastic particles increased the soil basal and cumulative respiration rate. Soil microbial biomass carbon increased during the 3th to 17th days of incubation, but decreased after that when compared to control treatment. LDPE Microplastic particles had a negative effect on the activity of acid and alkaline phosphatase and decreased them. The highest decline was related to the microplastic level of 4%. The rate of decrease in acid phosphatase activity was more than alkaline phosphatase activity. Briefly, the results of the present study showed that the microplastic particles can increase soil respiration, but it has a negative effect on phosphatase activity.

Choosing the best covering material for the greenhouse roof is a very important factor influencing the quantity and quality of light entering the greenhouse. Some vegetative and reproductive traits and biochemical characteristics of two tomato cultivars (‘Synda’ and ‘Melody’) grown in some greenhouse units roof-covered with four covering materials (glass, plastic, polycarbonate and corrugated polyethylene) were investigated for autumn cultivation in the Research Greenhouses of Ferdowsi University of Mashhad. This experiment was designed in a split plot (main-plot: greenhouse cover; sub-plot: cultivar) based on a completely randomized design. The highest to lowest radiation rates were recorded in corrugated polyethylene, glass, plastic and polycarbonate covers, respectively. The ANOVA results showed that vegetative, reproductive and biochemical traits were significantly affected by greenhouse cover, cultivar, or greenhouse cover × cultivar interaction. Raising the plant health index through increasing the stem diameter and decreasing plant length was influenced by the amount of the irradiation provided by greenhouse covers; it was significantly higher in the corrugated polyethylene and glass covers rather than the plastic and polycarbonate ones. The maximum numbers of days from transplanting to flowering stage were obtained in the corrugated and glass covers (35.5 and 35 days, respectively) for the ‘Synda’ cultivar, and in glass cover (32.2 days) for the ‘Melody’ cultivar. The lowest fruit ripening (60 days) was observed in the ‘Melody’ cultivar under the corrugated polyethylene cover, while the highest value (80.25 days) was recorded in ‘Synda’ cultivar under the polycarbonate cover. Fruit production was the highest in the ‘Synda’ cultivar under corrugated polyethylene (6503.6 g/plant) and glass (6337.3 g/plant) covers, while ‘Melody’ under plastic and polycarbonate covers (1314.2 and 1027.1 g/plant, respectively) showed the lowest amount. According to the results of this experiment, from an economic point of view, based on Net Present Value (NPV) and Internal Rate of Return (IIR) factors, the greenhouse cultivation of ‘Synda’ cultivar under glass cover is recommended in Mashhad climatic conditions.