Tillage and crop residue effects on soil carbon and carbon dioxide emission in corn-soybean rotations

Soil C change and CO2 emission due to different tillage systems need to be evaluated to encourage the adoption of conservation practices to sustain soil productivity and protect the environment. We hypothesize that soil C storage and CO2 emission respond to conservation tillage differently from conventional tillage because of their differential effects on soil properties. This study was conducted from 1998 through 2001 to evaluate tillage effects on soil C storage and CO2 emission in Clarion-Nicollet-Webster soil association in a corn [Zea mays L.]-soybean [Glycine max (L.) Merr.] rotation in Iowa. Treatments included no-tillage with and without residue, strip-tillage, deep rip, chisel plow, and moldboard plow. No-tillage with residue and strip-tillage significantly increased total soil organic C (TC) and mineral fraction C (MFC) at the 0- to 5- and 5- to 10-cm soil depths compared with chisel plow after 3 yr of tillage practices. Soil CO2 emission was lower for less intensive tillage treatments compared with moldboard plow, with the greatest differences occurring immediately after tillage operations. Cumulative soil CO2 emission was 19 to 41% lower for less intensive tillage treatments than moldboard plow, and it was 24% less for no-tillage with residue than without residue during the 480-h measurement period. Estimated soil mineralizable C pool was reduced by 22 to 66% with less intensive tillage treatments compared with moldboard plow. Adopting less intensive tillage systems such as no-tillage, strip-tillage, deep rip, and chisel plow and better crop residue cover are effective in reducing CO2 emission and thus improving soil C sequestration in a corn-soybean rotation.     

Determination of <Superscript>90</Superscript>Sr in milk and milk powder in Tehran and estimation of annual effective dose

Thirty-eight different milk and milk powder samples from Tehran-Iran were collected and analyzed for ⁹⁰Sr activity using a method in which the daughter product of ⁹⁰Sr decay (⁹⁰Y) was extracted by tributyl phosphate from ashed milk. ⁹⁰Y was then back extracted with water, and oxalate was precipitated . Following the sample analyzing, beta counting was performed with an ultralow-level liquid scintillation spectrometer. The quality control and assurance of the method were obtained by standard samples prepared with an IAEA-certified reference material. The mean determined ⁹⁰Sr activity concentration in the analyzed milk and milk powder (0.225 ± 0.042 and 0.216 ± 0.024 Bq kg⁻¹, respectively) showed that the radioactivity concentration in our samples was too low to induce biological hazards. These data can provide useful information of the background level of contamination, which in turn can be used in the following environmental monitoring programs.     

Moroccan actinobacteria with promising activity against toxic cyanobacteria Microcystis aeruginosa

Environmental Science and Pollution Research - In recent decades, harmful cyanobacterial blooms (HCBs) have become a severe hazard for human health mainly in drinking water resources and are...     

Challenges on the recycling of cigarette butts

Environmental Science and Pollution Research - Cigarette butt (CB)&nbsp;is a crucial litter in urban communities because it may contain various toxicants. Due to serious limitations on...     

A systematic review and meta-analysis of the impacts of glyphosate on the reproductive hormones

Environmental Science and Pollution Research - Worldwide use of glyphosate is constantly increasing and its residues are detected in drinking water, agriculture, and food products. There are...     

Extending the inverse receptance coupling method for prediction of tool-holder joint dynamics in milling

Recently, receptance coupling substructure analysis (RCSA) is used for stability prediction of machine tools through its dynamic response determination. A major challenge is the proper modelling of the substructures joints and determination of their parameters. In this paper, a new approach for predicting tool tip FRF is presented. First, inverse RCSA formulation is extended so that the holder FRFs can be identified directly through experimental modal tests. The great advantage of this formulation is its implementation in arbitrary point numbers along joint length. Therefore, in comparison with previous inverse RCSA approaches, a more realistic joint model can be considered. In addition, due to applying the new approach, additional costly modal tests on the gauged tool are not required. This characteristic makes it possible to determine the holder FRFs without separating the tool; especially in situations where the holder end is inaccessible. The inclusion of joint parameters effect in the identified holder FRFs is another main advantage of such approach. Consequently, for identification of joint parameters, there is no need to use common error optimization based on fitting methods. The effect of overhang length is investigated through some analytical study and also experimental validation. Results show that the predicted tool tip FRF is exact in analytical case. Moreover, due to less noise effect, the predictions based on identified FRFs of longer tools are more accurate than the shorter ones (in experimental case).     

Organophosphate dichlorvos induced dose‐related differential alterations in lipid levels and lipid peroxidation in various regions of the fish brain and spinal cord

Abstract

The effect of dichlorvos (DDVP) (0–0, dimethyl 2: 2‐dichlorovinyl phosphate), on various lipid fractions and lipid peroxidation in the discrete areas of the brain and spinal cord were studied in the fresh water teleost (Heteropneustes fossilis). Fishes were exposed to three different doses (3.0, 6.0 and 9.0 ppm) of DDVP daily for 7 days. Dose‐related increase in the levels of total lipids, cholesterol and esterified fatty acids was detected in the fore brain, optic lobes, cerebellum, medulla oblongata and spinal cord. However, phospholipids were significantly decreased in the aforementioned regions of the central nervous system. The rate of lipid peroxidation was significantly increased in all the regions of the CNS.     

Studies on factors affecting survival of nile fish in the Sudan. I. The effect of hydrogen ion concentration

Young of Tilapia nilotica L. were subjected to acidic and alkaline media of different pH over 24 h periods. Dilute hydrochloric acid was used to lower the hydrogen ion concentration of the test medium. A pH lower than 2.9 resulted in immediate mortality, whereas a pH of 3.5 and above produced no mortality. Alkaline media had no serious effect on survival.