- Volume:6 Issue:1, 2018
- تاریخ انتشار: 1397/01/30
- تعداد عناوین: 7
Soil Carbon Sequestration and Understory Plant Diversity under Needle and Broad-leaved Plantations (Case Study: Shahed Forest Park of Malayer City)Pages 1-10Aims: In relation to global climate changes, the issue of how forest ecosystems could affect biomass and soil carbon sequestration is essential.Materials and MethodsTo do this research, ailanthus (Ailanthus altissima Mill.) and Arizona cypress (Cupressus arizonica Greene) plantations were selected each one with an area of 20 hectare in forest park of Malayer, Western Iran. An adjacent area with no tree was selected as control. In each of the plantations and control area, ten plots of 20 × 20 m2 deployed and biomass of trees, biodiversity indices (ShannonWiener, Simpson, Menhinick, and Margalef indices), and carbon sequestration of aboveground tree biomass, belowground biomass, leaf litter, grass, and soil were measured.
Findings: The results showed that the carbon sequestration in Arizona cypress plantation (32.32 t ha−1) and the soil under it (11.15 t ha−1) was higher than that in ailanthus plantation and the soil under it (17.99 and 7.6 t ha−1, respectively). However, the soil carbon sequestration under both plantations was higher than that in control area (5.28 t ha−1). According to the results, it was found that herbaceous understory of ailanthus plantation had stored carbon more than arizona cypress plantation. Furthermore, the results indicated that there is a significant difference between two plantations from the point view of the understory plant diversity (Menhinick index in ailanthus and Arizona cypress plantations was 3.17 and 2.44, respectively).ConclusionThis research confirms that plantation with Arizona cypress tree is more efficient in soil and tree biomass carbon sequestration than plantation with ailanthus trees. Furthermore, according to the results, the understory plant richness in ailanthus plantation was higher than that in arizona cypress.Keywords: Biodiversity Indices, Organic Carbon, Plantation, Tree Biomass
Runoff Simulation using WetSpa Distributed Hydrological Model in Ziarat Watershed of Golestan Province, IranPages 11-20Aims: Modeling precipitation-runoff processes and forecasting river flow are an essential step in floods management and controlling, designing water structures in watersheds and droughts management.Materials and MethodsIn the present research, WetSpa distributed hydrological model was applied to simulate river flow in Ziarat watershed of Golestan Province. This basin has an area of 95 km2 and it has an average height of 1760 m above sea level. As a distributed, continuous, and physical model, WetSpa is characterized with daily or hourly time series which accounts for processes of precipitation, runoff, and evapotranspiration contexts. The model parameters include distributive and global parameters. To run model, daily data on flow, precipitation, temperature, and evaporation for years 20082016 were considered for calibration and validation.
Findings: The results of simulation showed a relatively good compatibility between calculated and measured hydrograph at the basin outlet. According to Nash-Sutcliffe model for calibration periodic model, efficiency coefficient estimated daily hydrographs and maximum flow rate by 57.32% and 84.11% accuracy, respectively. However, given NashSutcliffe coefficient which was equaled to −385.39 and −209.06 for low and high flow, respectively, validation results are not acceptable which it can be attributed to water withdrawal and diversion dam for water harvesting before gauging stations in outle.ConclusionGiven the calibration results, WetSpa model has great efficiency under high flow circumstances compared to low flow mainly due to model weakness in low flow estimation but as a whole model simulated total flow with acceptable accuracy.Keywords: Flow Simulation, Precipitation, runoff Models, Calibration, Validation, Ziarat Basin
Effect of Humic Acid on Germination, Growth, and Photosynthetic Pigments of Medicago sativa L. under Salt StressPages 21-30Aims: Salt stress is one of the most important environmental stresses that cause to reduce biological function in plants. In this context, appropriate biotech is needed that would not only improve the productivity of the product but also improve the soil. Regarding the problem, the use of humic acid in addition to the positive effects on soil properties, it is useful in terms of economic, environmental, and social aspects and can be an appropriate alternative to chemical fertilizers.Materials and MethodsThe present research was conducted as a factorial experiment in a completely randomized design. The first factor was humic acid (0, 0.009 mg Li−1). The second factor was salt stress, which was applied at three levels of 2, 6, and 12 dS m−1. In each treatment, seed germination, seed vigor index, growth traits (allometric coefficient, radicle and pedicle length, total dry, and fresh weight), and photosynthetic contents of Medicago sativa L. were measured.
Findings: The findings showed that under salt stress, humic acid increased the seed germination of M. sativa L. Humic acid was effective in increasing the plant growth. In connection with the photosynthetic contents, the humic acid showed positive effects, especially in terms of 2 and 12 dS m−1 salinity levels, respectively.ConclusionIn general, humic acid had high impact on reducing the negative impacts of saltstress. Due to the fact that majority of the worlds rangelands are in arid and semi-arid areas, and salt stress is one of the most important factors in reduced plant growth, more comprehensive and accurate survey in the field is recommended.Keywords: Environmental Stress, Humic Acid, Plant Growth, Seed Vigor Index
Recovery of Bioactive Peptide Fractions from Rainbow Trout (Oncorhynchus mykiss) Processing Waste HydrolysatePages 31-40Aims: Bioactive peptides with antioxidant properties derived from fish by-products and wastes by enzymatic hydrolysis have become a topic of great interest for pharmaceutical, health food, and processing/preservation industries.
Materials & Methods This study aimed to characterize peptide fractions with antioxidative activity recovered from rainbow trout gelatin hydrolysate. Four peptide fractions (30 kDa) were obtained from gelatin hydrolysate by subjecting them to centrifugal ultrafiltration using successively a 30 kDa, 10 kDa, and a 3 kDa membrane. The 1030 kDa fraction was characterized in terms of amino acid composition. The antioxidant activity of all fractions was monitored by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azino bis(3-ethylbenzthiazoline)-6-sulfonic acid (ABTS) radical scavenging as well as reducing power activity.
Findings: The free amino acids in 1030 kDa fraction were dominated by Gly, Pro, Ala, and Hyp; the total hydrophobic amino acid of 1030 kDa fraction was also 61.5%. All hydrolysate and peptidic fractions demonstrated high antioxidant activities. Moreover, 1030 kDa fraction exhibited the highest DPPH and ABTS radical scavenging activity (2, 5, and 10 mg ml−1) and reducing power (10 mg ml−1) compared to other fractions (pConclusionThese results revealed the potential of peptide fractions recovered from rainbow trout skin gelatin as source of natural antioxidants for use in food products.Keywords: Bioactivity, Fish Waste, Peptidic Fractions, Rainbow Trout, Recovery
Estimation of Soil Organic Carbon in a Small-Scale Loessial Hillslope Using Terrain Derivatives of Northern IranPages 41-54Aims: Soil organic carbon (SOC) is contemplated as a crucial proxy to manage soil quality, conserve natural resources, monitoring CO2 and preventing soil erosion within the landscape, regional, and global scale. Therefore, the main aims of this study were to (1) determine the impact of terrain derivatives on the SOC distribution and (2) compare the different algorithms of topographic wetness index (TWI) calculation for SOC estimation in a small-scale loess hillslope of Toshan area, Golestan province, Iran. (3) Comparison between multiple linear regression (MLR) and artificial neural networks (ANN) methods for SOC prediction.Materials and Methodstotal of 135 soil samples were taken in different slope positions, i.e., shoulder (SH), backslope (BS), footslope (FS), and toeslope (TS). Primary and secondary terrain derivatives were calculated using digital elevation model (DEM) with a spatial resolution of 10 m × 10 m. To SOC estimation (dependent variable) was applied two models, i.e., MLR and ANN with terrain derivatives as the independent variables.
Findings: The results showed significant differences using Duncans test in where TS position had the higher mean value of SOC (25.90 g kg−1) compared to SH (5.00 g kg−1) and BS (12.70 g kg−1) positions. The present study also revealed which SOC was more correlated with TWIMFD (Multiple-Flow-Direction) and TWIBFD (Biflow-Direction) than TWISFD (Single Flow Direction). The MLR and ANN models were validated by additional samples (25 points) that can be explain 65% and 76% of the total variability of SOC, respectively, in the study area.ConclusionThese results indicated that the use of terrain derivatives is a beneficial method for SOC estimation. In general, an accurate understanding of TWIMFD is needed to better estimate SOC to evaluate soil and ecosystem related effects on global warming of as this hilly region at a larger scale in a future study.Keywords: Artificial Neural Networks, Different Flow Direction, Loess, Multiple Linear Regression
Determination of Heavy Metals Concentration at Water Treatment Sites in Ahwaz and Mollasani Using BioindicatorPages 55-66Aims: Karun River, which is the largest river in Iran, represents a unique ecosystem. However, increased anthropogenic activities result in the formation of this river is seriously affected by a large range of pollutants especially the heavy metal pollutants which may be toxic to human and aquatic fauna. Therefore, there is a need for continuous monitoring of pollution levels in the river.Materials and MethodsIn this study, water, sediment, and algae samples were collected from six different stations along the course of the river in September 2015 to investigate the quality of Karuns River in terms of heavy metals (Pb, Zn, Cr, and Cd) at the basin of drinking water treatment in Ahwaz and Mollasani cities. After drying and digestion of samples, heavy metal concentrations were determined using an atomic absorption spectrophotometry (Perkin Elmer-Analyst 300).
Findings: The highest concentration of trace metals was found in sediment samples with Zn having the highest mean concentration values in all stations. The heavy metal concentrations in the downstream indicated an increase in the pollution load due to the flow of water from upstream to downstream of the river resulted in the movement and accumulation of all contaminants to the river in the downstream; hence, there was the highest concentration of metals in basin of the Kut Abdollah treatment (downstream) and the lowest in Mollasani (upstream).ConclusionComparison of the concentration of metals in the sediments with some universal standards including EPA3050 and the criterion of sediments quality standard from NOAA and Canadian Environment Agency showed that the concentration of chromium and cadmium in stations was higher than the allowable limit of EPA3050 standards and some environmental standards of Canada among all metals. Since algae samples have been able to accumulate a significant amount of heavy metals, therefore, these are suitable bio-indicators to determine the concentration of heavy metals in this aquatic ecosystems.Keywords: Algae, Heavy Metals, Karun River, Sediment, Water Treatment
The Effects of Airborne Pollutants and Climatic Factors of Different Sections of Tehran Areas on Leaf Characteristics of Oriental Plane (Platanus orientalis L.) TreesPages 67-78Aims: This study was carried out to determine the effects of urban gaseous pollutants (sulfur dioxide [SO2], nitrogen dioxide [NO2], and ozone [O3]) and climatic factors (temperature and precipitation) on the morphological and anatomical reaction of Platanus orientalis L. in Tehran.Materials and MethodsSeven districts of this city with a wide spectrum of climatic conditions and diversity of elevation were selected, and gas concentration of SO2, NO2, and O3 was determined. Then, morphological and anatomical parameters of this plant including leaf area, specific leaf area (SLA), wet and dry weight, leaf toughness and thickness, water content, lamina, and main vein were measured and the analysis of their correlations with environmental (climatic and pollutant) factors along with their t-tests were evaluated.
Findings: The results showed that the climatic factors made significant (PConclusionThe results explain that anatomical and morphological characteristics of P. orientalis leaves have been influenced by environmental stresses and changes in these factors show the resistance of the plant to the environmental conditions.Keywords: Air Pollution, Climate, Platanus orientalis, Specific Leaf Area