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Soil erosion is one of the most serious environmental issues in the world. The use of vegetative buffer strips is an effective strategy to reduce surface water pollutions as well as soil erosion. The present research has been conducted with aim to study the efficiency of buffer strips in runoff volume and sediment control using experimental plots. In this regard, twelve experimental plots with the dimensions of 1 m × 10 m were provided, and runoff samples were collected monthly to measure runoff volume and sediment. Vetiver grass and tall fescue were used as the plant species of the studied vegetative buffer strips. It was found that, vegetative buffer strips reduced the runoff volume up to 97% and sediment concentration up to 96%. Vetiver grass showed a high efficiency in runoff and sediment control; but, the maximum efficiency is achieved when this species is used along with a plant similar to the tall fescue in terms of density and uniformity. Also, periodic cutting the plants and cleaning the buffer strips can be considered as effective strategies to prevent vegetative buffer strips acting as the source of sediment.

There is a need to analyze and map rainfall erosivity to assess soil erosion at the regional scale. The objectives of this study were to develop a regional model to estimate seasonal erosivity from seasonal rainfall data and to study temporal and spatial distribution of rainfall erosivity for the Gorganrood drainage basin in the northeast of Iran. Six gauging stations with a high temporal resolution (15 min) and eleven monthly totals stations located into the study area have been used. Regression models for pluviograph stations indicated that storm rainfall explained 22-51% of the variation in storm erosivity. But, at the seasonal scale, the explained variation increased to 62-86% and modified coefficient of efficiency increased from 0.12-0.29 to 0.38-0.64. Also, the results of ANOVA showed that EI30 values have significant difference between autumn/ summer seasons and winter/spring seasons. Interpolation surfaces were created from all 17 stations seasonal values using the local polynomial algorithm. The results showed, during the wet season, erosivity varied from 438 Mj/mm/h (west) to 1015 Mj/ mm/h (Middle). But, in the dry season, values of erosivity were lower than from values in wet season and the highest values were at the middle parts of the study area and the lowest were at the eastern and the western parts of the study area. Our findings provide good guidance to integrate pluviograph and pluviometric data for rainfall erosivity assessment in regional scales, where short duration rainfall intensity data, usually are not available. [ABSTRACT FROM AUTHOR]

Immobilization of enzyme onto nanoparticles such as chitosan can have biotechnological importance. In this study, chitosan nanoparticles (ChNPs) were prepared by Ionic gelation method and Endoglucanase Cel9A from Alicyclobacillus acidocaldariius (AaCel9A) immobilized on the nanoparticles. The FTIR results showed that the enzymes were immobilized on the ChNPs. The dynamic light scattering and scanning electron microscope (SEM) results illustrated that the AaCel9A-ChNPs approximately had 40 nm diameters. For optimizing enzyme immobilization, response surface methodology was employed using different variables (pH, enzyme immobilization time, and enzyme to ChNPs ratio [E/Cs]). The results showed that the high immobilization efficiency was achieved in pH 7, E/Cs of 0.4 in 2.63 hr. The enzyme activity results showed that, immobilization increased optimum pH for activity (from 6.5 to 7.5) and the enzyme K m (from 3.703 to 12.195 [mg/ml]), which make it suitable to use in some industries such as detergents., (© 2020 American Institute of Chemical Engineers.)