Simultaneously decreasing arsenic and cadmium in rice by soil sulfate and limestone amendment under intermittent flooding.

Water management in paddy soils can effectively reduce the soil-to-rice grain transfer of either As or Cd, but not of both elements simultaneously due to the higher mobility of As under reducing and Cd under oxidizing soil conditions. Limestone amendment, the common form of liming, is well known for decreasing Cd accumulation in rice grown on acidic soils. Sulfate amendment was suggested to effectively decrease As accumulation in rice, especially under intermittent soil flooding.

Arsenic Thiolation in Rice and .

Inorganic and methylated thioarsenates have recently been reported to form in paddy soil pore waters and accumulate in rice grains. Among them, dimethylmonothioarsenate (DMMTA) is particularly relevant because of its high cytotoxicity and potential misidentification as nonregulated dimethylarsenate (DMA). Studying DMMTA uptake and flag leaf, grain, and husk accumulation in rice plants during grain filling, substantial dethiolation to DMA was observed with only 8.

Widespread occurrence of dimethylmonothioarsenate (DMMTA) in rice cakes: Effects of puffing and storage.

Thioarsenates have recently been detected in rice and rice-based products, with particularly high contents in puffed rice cakes. Here, we show that puffing rice can cause almost complete transformation of dimethylarsenate (DMA) to dimethyldithioarsenate (DMDTA) and dimethylmonothioarsenate (DMMTA). Analysis of puffed rice cakes after 3 months of non-sealed storage at room temperature showed transformation of DMDTA mainly into DMMTA.

Consequences of sea level rise for high metal(loid) loads in the Ría of Huelva estuary sediments.

Ría of Huelva, located in southwestern Spain, is a highly metal(loid)-contaminated estuary system where sediments are exceeding action limits in an increasing order for Cd, Zn, Pb, Cu, and As. With a predicted sea level rise over the next 50 years, the estuary will be subject to flooding with brackish water or seawater. To evaluate the risk of metal(loid) mobilization under future climate scenarios, different locations along the estuary were sampled at different depths.

Decreasing arsenic in rice: Interactions of soil sulfate amendment and water management.

Accumulation of inorganic arsenic (iAs) and dimethylarsenate (DMA) in rice threatens human health and rice yield, respectively. We studied the yet unclear interactions of soil sulfate amendment and water management for decreasing As accumulation in rice grain in a pot experiment. We show that soil sulfate amendment (+200 mg S/kg soil) decreased grain iAs by 44% without clearly increasing grain DMA under intermittent flooding from booting stage to maturation.

Dimethylated Thioarsenates: A Potentially Dangerous Blind Spot in Current Worldwide Regulatory Limits for Arsenic in Rice.

Arsenic (As) occurrence in rice is a serious human health threat. Worldwide, regulations typically limit only carcinogenic inorganic As, but not possibly carcinogenic dimethylated oxyarsenate (DMA). However, there is emerging evidence that "DMA", determined by routine acid-based extraction and analysis, hides a substantial share of dimethylated thioarsenates that have similar or higher cytotoxicities than arsenite.

Dimethylmonothioarsenate Is Highly Toxic for Plants and Readily Translocated to Shoots.

Arsenic is one of the most relevant environmental pollutants and human health threats. Several arsenic species occur in soil pore waters. Recently, it was discovered that these include inorganic and organic thioarsenates.

Detection of Thioarsenates in Rice Grains and Rice Products.

Inorganic and methylated thioarsenates have recently been reported to contribute substantially to arsenic (As) speciation in paddy-soil pore waters. Here, we show that thioarsenates can also accumulate in rice grains and rice products. For their detection, a method was developed using a pepsin-pancreatin enzymatic extraction followed by chromatographic separation at pH 13.

Methylated Thioarsenates and Monothioarsenate Differ in Uptake, Transformation, and Contribution to Total Arsenic Translocation in Rice Plants.

Methylated and inorganic thioarsenates have recently been reported from paddy fields besides the better-known oxyarsenates. Methylated thioarsenates are highly toxic for humans, yet their uptake, transformation, and translocation in rice plants is unknown. Here, hydroponic experiments with 20 day old rice plants showed that monomethylmonothioarsenate (MMMTA), dimethylmonothioarsenate (DMMTA), and monothioarsenate (MTA) were taken up by rice roots and could be detected in the xylem.