The bioaccessibility of iodine in the biofortified vegetables throughout cooking and simulated digestion.

Biofortification of crops with exogenous iodine is a novel strategy to control iodine deficiency disorders (IDD). The bioaccessibility of iodine (BI) in the biofortified vegetables in the course of soaking, cooking and digestion, were examined. Under hydroponics, the concentration of iodine in leafstalks of the celery and pakchoi increased with increasing exogenous iodine concentration, 54.8-63.9% of the iodine absorbed by pakchoi was stored in the soluble cellular substance. Being soaked in water within 8 h, the iodine loss rate of the biofortified celery was 3.5-10.4% only. More than 80% of the iodine in the biofortified celery was retained after cooking under high temperature. The highest BI of the biofortified vegetables after digestion in simulated gastric and intestinal juice amounted to 74.08 and 68.28%, respectively. Factors influencing BI included pH, digestion duration, and liquid-to-solid ratio. The high BI of the biofortified vegetables provided a sound reference for the promotion of iodine biofortification as a tool to eliminate the IDD.

An innovative approach for iodine supplementation using iodine-rich phytogenic food.

Iodine, as one of the essential trace elements for human body, is very important for the proper function of thyroid gland. In some regions, people are still suffering from iodine deficiency disorder (IDD). How to provide an effective and cost-efficient iodine supplementation has been a public health issue for many countries. In this review, a novel iodine supplementation approach is introduced. Different from traditional iodine salt supplement, this approach innovatively uses cultivated iodine-rich phytogenic food as the supplement. These foods are cultivated using alga-based organic iodine fertilizer. The feasibility, mechanics of iodine absorption of plants from soil and the bioavailability of iodine-rich phytogenic food are further discussed.

Numerical simulations of the Macondo well blowout reveal strong control of oil flow by reservoir permeability and exsolution of gas.

In response to the urgent need for estimates of the oil and gas flow rate from the Macondo well MC252-1 blowout, we assembled a small team and carried out oil and gas flow simulations using the TOUGH2 codes over two weeks in mid-2010. The conceptual model included the oil reservoir and the well with a top boundary condition located at the bottom of the blowout preventer. We developed a fluid properties module (Eoil) applicable to a simple two-phase and two-component oil-gas system. The flow of oil and gas was simulated using T2Well, a coupled reservoir-wellbore flow model, along with iTOUGH2 for sensitivity analysis and uncertainty quantification. The most likely oil flow rate estimated from simulations based on the data available in early June 2010 was about 100,000 bbl/d (barrels per day) with a corresponding gas flow rate of 300 MMscf/d (million standard cubic feet per day) assuming the well was open to the reservoir over 30 m of thickness. A Monte Carlo analysis of reservoir and fluid properties provided an uncertainty distribution with a long tail extending down to 60,000 bbl/d of oil (170 MMscf/d of gas). The flow rate was most strongly sensitive to reservoir permeability. Conceptual model uncertainty was also significant, particularly with regard to the length of the well that was open to the reservoir. For fluid-entry interval length of 1.5 m, the oil flow rate was about 56,000 bbl/d. Sensitivity analyses showed that flow rate was not very sensitive to pressure-drop across the blowout preventer due to the interplay between gas exsolution and oil flow rate.

Biogeochemical transfer and dynamics of iodine in a soil-plant system.

Radioactive iodide (125I) is used as a tracer to investigate the fate and transport of iodine in soil under various leaching conditions as well as the dynamic transfer in a soil-plant (Chinese cabbage) system. Results show that both soils (the paddy soil and the sandy soil) exhibit strong retention capability, with the paddy soil being slightly stronger. Most iodine is retained by soils, especially in the top 10 cm, and the highest concentration occurs at the top most section of the soil columns. Leaching with 1-2 pore volume water does not change this pattern of vertical distributions. Early breakthrough and long tailing are two features observed in the leaching experiments. Because of the relatively low peak concentration, the early breakthrough is really not an environmental concern of contamination to groundwater. The long tailing implies that the retained iodine is undergoing slow but steady release and the soils can provide a low but stable level of mobile iodine after a short period. The enrichment factors of 125I in different plant tissues are ranked as: root > stem > petiole > leaf, and the 125I distribution in the young leaves is obviously higher than that in the old ones. The concentrations of 125I in soil and Chinese cabbage can be simulated with a dual-chamber model very well. The biogeochemical behaviors of iodine in the soil-cabbage system show that cultivating iodized cabbage is an environmentally friendly and effective technique to eliminate iodine deficiency disorders (IDD). Planting vegetables such as cabbage on the 129I-contaminated soil could be a good remediation technique worthy of consideration.

Mechanism of iodine uptake by cabbage: effects of iodine species and where it is stored.

Iodine-enhanced vegetable has been proven to be an effective way to reduce iodine deficiency disorders in many regions. However, the knowledge about what mechanisms control plant uptake of iodine and where iodine is stored in plants is still very limited. A series of controlled experiments, including solution culture, pot planting, and field experiments were carried out to investigate the uptake mechanism of iodine in different forms. A new methodology for observing the iodine distribution within the plant tissues, based on AgI precipitation reaction and transmission electron microscope techniques, has been developed and successfully applied to Chinese cabbage. Results show that iodine uptake by Chinese cabbage was more effective when iodine was in the form of IO(3) (-) than in the form of I(-) if the concentration was low (<0.5 mg L(-1)), but the trend was opposite if iodine concentration was 0.5 mg L(-1) or higher. The uptake was more sensitive to metabolism inhibitor in lower concentration of iodine, which implies that the uptake mechanism transits from active to passive as the iodine concentration increases, especially when the iodine is in the form of IO(3) (-). The inorganic iodine fertilizer provided a quicker supply for plant uptake, but the higher level of iodine was toxic to plant growth. The organic iodine fertilizer (seaweed composite) provided a more sustainable iodine supply for plants. Most of the iodine uptake by the cabbage is intercepted and stored in the fibrins in the root while the iodine that is transported to the above-ground portion (shoots and leaves) is selectively stored in the chloroplasts.

Characterization of flow and transport processes within the unsaturated zone of Yucca Mountain, Nevada, under current and future climates.

This paper presents a large-scale modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, a potential repository site for storing high-level radioactive waste. The study has been conducted using a three-dimensional numerical model, which incorporates a wide variety of field data and takes into account the coupled processes of flow and transport in the highly heterogeneous, unsaturated fractured porous rock. The modeling approach is based on a dual-continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. Various scenarios of current and future climate conditions and their effects on the unsaturated zone are evaluated to aid in the assessment of the proposed repository's system performance using different conceptual models. These models are calibrated against field-measured data. Model-predicted flow and transport processes under current and future climates are discussed.