Identifying Controlling Factors of Bioaccumulation of Selected Metal(loid)s in Various Soil–Cereal Crop Systems within Cultivated Fluvisols

The paired Fluvisol and cereal samples in both the field screening and controlled experiments are reported to elucidate the soil–crop relationship for As, Cd, and Pb in relation to changing contamination levels. Significant varietal differences in plant uptake were observed for crop type (barley, triticale) and the harvested part of the crop (oat shoots and grain). When parametrizing the stepwise regression models, the inclusion of soil properties often improved the performance of soil–crop models but diverse critical soil parameters were retained in the model for individual metal(loid)s. The pH value was often a statistically significant variable for Cd uptake. For As and Pb, the more successful model fit was achieved using the indicators of quantity or quality of soil organic matter, but always with lower inherent model reliability compared to Cd. Further, a single correlation analysis was used to investigate the relationship between extractable metal concentrations in soil solution and their crop accumulation. For Cd, there were strong intercorrelations among single extractions, the NH4NO3 extraction stood out with perfect correlation with plant uptake in both experiments. For As and Pb, the CaCl2 and Na2EDTA solutions outperformed other single extractions and were the better choice for the assessment of depositional fluvial substrates.

Tranexamic Acid Tamponade to Control Postoperative Surgical Hemorrhage

When preparing for oral surgery, patients taking anticoagulants usually should not discontinue their medication because of the risk of a thromboembolic event. The therapeutic effect of many anticoagulants is not readily measured, so preoperatively, the surgeon cannot know the true risk for postoperative hemorrhage. The risk of a thromboembolic event usually outweighs the concerns of controlling postoperative hemorrhage. Hemophilia patients are also at risk for postoperative bleeding. Single extractions probably do not pose a serious risk for postoperative hemorrhage. However, when a mucogingival flap is raised in these patients, there may be prolonged bleeding. Surgical sponges saturated with aqueous tranexamic acid solution and compressed onto the bleeding site with biting pressure may stop bleeding. Bleeding was stopped in the case example presented here after three 10-minute compressions over 30 minutes in a patient taking aspirin and clopidogrel for a previous thromboembolic event and a metal coronary stent. The clot formed is very fragile and is prone to bleeding, so it should not be disturbed. This technique needs to be studied for efficacy.

Assessment of the phytoavailability of Cu and Ni using various extraction procedures

The phytoavailability of copper (Cu) and nickel (Ni) in soils from Bangladesh was assessed. The uptake by Ipomoea aquatica and Oryza sativa L. was measured and a range of extractants tested on soils and plant tissue samples. Extractants tested were distilled water, 1 M NH4Cl, 0.01 M CaCl2, 0.005 M diethylenetriamine penta‐acetic acid (DTPA), 0.1 M ethylenediamine tetraacetic acid (EDTA), 0.1 M HCl and 1 M HCl. The extractability of the metals varied depending on the metal species, the crop and the extractant used. The best extractant was 1 M HCl, which extracted the highest amount of the heavy metals and correlated most strongly with their plant uptake measures. The use of 1 M HCl is, therefore, recommended for first‐level screening of soils contaminated with heavy metals if only one extractant is to be used. Sequential extraction showed that Cu was associated mostly with the 0.005 M DTPA and 0.1 M EDTA extractable fractions, while Ni was associated with the 0.1 M HCl and 1 M HCl fractions in most cases. The fractions of metals extracted using the sequential extraction procedure varied compared to single extractions for all soil types. Dhaka Univ. J. Biol. Sci. 24(1): 1-16, 2015 (January)

A Critical Evaluation of Single Extractions from the SMT Program to Determine Trace Element Mobility in Sediments

Two commonly applied single extractions procedures, namely extractions with ammonium-EDTA and acetic acid, were evaluated based on the analysis of 72 samples from alluvial sediments. For most trace elements (Cu, Zn, Cd, Ni, As, and Pb), a significant linear relationship could be established between their ammonium-EDTA or acetic acid extractable concentrations and their total concentrations, the organic carbon content, pH, and Fe , Al, and/or Ca content in the sediments. The scientific understanding of trace element partitioning in the complex soil-water system with these simple models is rather limited, but they offer the opportunity to use data from single extractions in a more comprehensive way. Despite the fact that these extractions cannot directly be related to the bioavailability of elements, they can provide input data for use in risk assessment models. Additionally, they also offer possibilities to perform a fast screening of the mobilizable pool of elements in soils and/or sediments.