A laboratory preparation procedure for studying bioaccumulation of U and its subcellular form in earthworms (Diplocardia spp.).

Uranium (U) is a ubiquitous trace element in soils. With increasing in application of U in nuclear energy and nuclear weapon, a large amount of U was dissipated into the environment including soil and water. Earthworm may be an eco-indicator for U bioaccumulation, transformation and transport across the ecosystem. There have been a variety of methods preformed to assess the bioaccumulation of uranium in small organisms such as earthworms, including uranium speciation, subcellular separation, and total U accumulation. All methods require an initial grinding preparation process that allows for the further fractionation of metals and metalloids in earthworms. The slime like mucus that coats the body of a worm presents a challenge in the disintegration and dissolution of the worm body. In order to analyze U subcellular forms, we developed a reliable and effective procedure to grind the worm body into a uniform fine suspension. We conducted a comparative study of disintegration of worms with 3 grinding techniques (agate mortar, liquid nitrogen freezing then agate mortar, and direct sonication) that would assist U subcellular analyses and bioaccumulation. The essences of this new development was as follows:•A scheme for preparation of earthworm samples for investigation of subcellular U forms in earthworms from U.S. army weapon test range soil with various U forms.•The direct sonication of earthworms was found to be the most proficient process in achieving the best preparation for U subcellular analyses with the high precision.

A laboratory simulation to investigate effects of moistures on U distribution among solid phase components in army range soils.

Uranium is a naturally occurring radioactive trace element found in rocks, soils, and coals. U may contaminate groundwater and soil from nuclear power plant operations, spent fuel reprocessing, high-level waste disposal, ore mining and processing, or manufacturing processes. Yuma Proving Ground in Arizona, USA has been used depleted uranium ballistics for 36 years where U has accumulated in this army testing site. The objective of this study is to develop a laboratory scheme on the effects of soil moisture regiments on the distribution and partitioning of U in army range soil among solid phase components to mimic U biogeochemical processes in the field. Three moisture regiments were saturated paste, field capacity, and wetting-drying cycle which covered major scenarios in fields from the wet summer season to the dry winter season. Uranium in soils with different forms of U (UO2, UO3, uranyl, and schoepite) was fractionated into 8 operationally defined solid components with sequential selective dissolution procedure. The essences of this new development were as following:•A scheme was developed for investigation of U distribution, partitioning and transformation among solid phase components in army weapon test range soils with various U forms under 3 soil moisture regimes.•Soil moisture was one of major environmental factors in controlling biogeochemical processes and fates of U in army weapon test site.

Phytoremediation uptake model of heavy metals (Pb, Cd and Zn) in soil using Nerium oleander.

Phytoremediation is an important and effective tool to remove different contaminations in the soil, water and air. The main objective of this research was to evaluate the effect of phytoremediation using one species of shrubs, Nerium oleander plants, on reducing the heavy metals (HMs) contamination in the soil. The present study was carried out during 2015 in El-Dakhyla (industrial zone), Alexandria Egypt. A simple Uptake Plant Model (UPM) was used to estimate the contribution of various pathways in remediating ((Lead (Pb), Cadmium (Cd) and Zinc (Zn)) through different parts, in one of the evergreen shrubs (leaves, stem and root). These include soil-root-leaf pathway, soil-air-leaf pathway, and its deposition. The model calculations revealed that the (Root concentration Factor) log RCF of the root equals 0.5, 0.41, and 0.45, respectively. The Translocation Stem Concentration Factor (TSCF) of the upward in the xylem equals 0.85, 0.98 and 0.99. Moreover, the Bioaccumulation Factors (log BCF) of the soil is 1.32, 0.014 and 0.061. In addition, the partition coefficient of Octanol-Water (log Kow) is 4.67, 2.75, and 3.35, respectively. Therefore, one may conclude that Pb was accumulated in the root, while Cd and Zn were concentrated in the aerial parts of the Nerium oleander plant. On the other hand, Pb considered one of the heavy metals where it's movement in the plants is slower than Cd and Zn due to its molecular weight is bigger than the latter HMs.

Evaluation of the phytoremediation uptake model for predicting heavy metals (Pb, Cd, and Zn) from the soil using Nerium oleander L.

The experiment was carried out during two seasons (spring and autumn) of the year 2015, in El-Max (industrial zone) and Antoniadis park (control zone), Alexandria, Egypt. Nerium oleander L. plants has been used in this experiment because of its capability to remediate heavy metals (HMs) from the soil. This study aimed to evaluate the performance of the Phytoremediation Uptake Model (UPM) in predicting the uptake of HMs (lead (Pb), cadmium (Cd), and zinc (Zn)) from the soil. UPM was used to estimate the contribution of various pathways in the remediation of these HMs through different parts, leaves, stem, and root. Besides, it includes soil-root-leaf and soil-leaf pathways and its deposition. The performance of the UPM has been examined using many statistical calculations tools (Person correlation coefficient (R2), root mean square error (RSME %), mean bias error (MB %), and Willmott index of agreement degree (d)). The results showed a high harmony between the UPM predictions and the experiment. Moreover, most R2 values are ranged mostly between 0.97 and 0.99 during the spring and the autumn in the study areas. Therefore, the correlation is very strong between the measured and the predicted HMs concentrations. In addition, the less value of RMSE% (0.13) was obtained in the lower parts of the plant, while the greatest value was observed in leaf model (42.53). Also, the values of MB% were acceptable and within the range between 3.01 and 10.41. In addition, the values of the Willmott index of the agreement were within the acceptable range (0.80 to 0.97). Thus, one may conclude that the UPM has proved a high performance in estimating the uptake and removal of different concentrations of HMs from soil under different spatial and temporal conditions.