Polished Rice Grains Research Articles

Residue and dissipation kinetics of novel nematicide fluopyram in rice assessed by QuEChERS-liquid chromatography-tandem mass spectrometry.

Supervised field trial was conducted to study the dissipation pattern of fluopyram in rice plant after application of fluopyram 400g/L SC(Velum Prime) as soil drenching at the time of sowing in nursery bed at X (500g a.i. ha-1) and 1.25X (625.2g a.i. ha-1) doses. Samples of rice plant were collected on 0, 1, 3, 7, 10, 15, and 20days after transplanting. QuEChERS-based extraction method was validated and adopted to determine the residues of fluopyram in rice seedlings, whole rice grains (with husk), polished rice grain, husk, straw, and soil using LC-MS/MS (liquid chromatography-tandem mass spectrometry).The initial deposit of fluopyram in rice plant recorded were 0.27 and 0.41mgkg-1in X and 1.25X doses, respectively. Fluopyram residues dissipated following first-order kinetics with half-life of 2.53 and 2.57days at X and 1.25X doses, respectively. Residues were detected in seedlings up to 15days after transplanting and were at below LOQ in whole rice grains (with husk), polished rice grain, husk, straw, and soil collected at harvest. Monitoring study revealed that application of novel nematicide fluopyram for the management of nematodes in rice does not pose any risks to consumers.

Effect of different type of rice grains on angoumous grain moth, Sitotroga cerealella (olivier)

A study was carried out to know the effect of different type of rice grains on development and survival of Angoumois grain moth, Sitotroga cerealella (Olivier). The maximum adult emergence were recorded in dehusked grain, which was significantly superior over rest of the grain types and was followed by grain with husk, degermed grain soaked in water and degermed grain without soaking. The growth index was highest in dehusked unpolish grain and was followed by the grain with husk. The pest could not developed on polished rice grains. . KEYWORDS :Rice, grain types, Angoumois grain moth, Sitotroga cerealella (Olivier), development, survival

Dynamics of selenium-mercury interaction under mercury stress in high and low selenium rice genotypes

Recent studies have demonstrated that selenium (Se) reduces the accumulation of heavy metals in rice tissues. However, the interaction between Se and mercury (Hg) in rice genotypes with high Se content remains to be further investigated. In this study, we used high Se genotypes Z2057B and Z5097B and low Se genotype Yuenong to explore the dynamics of Se and Hg in various tissues. The results showed that high Se genotypes, coupled with low concentrations of exogenously applied Se, significantly reduced the uptake of Hg in rice plants. The findings indicated the following order of Hg accumulation: Roots> third leaf > second leaf > first leaf > stem > grains. Observations revealed that both high Se genotypes and Se supplementation significantly restricted the majority of Hg concentration in roots and minimized its translocation to the aerial parts of the rice plant. In high Se genotypes subjected to mercury stress, MDA accumulation was significantly reduced, and SOD antioxidant activity was enhanced in stem and leaves at jointing, booting, heading, and maturity stages as compared to low Se genotypes. The application of 1.0 mg of Se per kg soil significantly improved the agronomic and physiological characteristics, reduced the Hg contents in aerial parts, and increased the Se contents in polished rice grains. Hence, the results lead to the conclusion that (i) cultivating high Se rice genotypes is a viable approach to decrease the Hg accumulation in rice grains and serves as a crucial strategy to fulfill daily Se requirements, particularly for populations suffering from Se deficiency (ii) supplementing ordinary rice with 1–3 mg kg−1 of Se can effectively reduce Hg accumulation and improve the quality of the grains.

Evaluation of the efficacy of cinnamon oil on Aspergillus flavus and Fusarium proliferatum growth and mycotoxin production on paddy and polished rice: Towards a mitigation strategy

In the present investigation, the effect of cinnamon oil (CO) (10, 30, 50 and 70 %) on the growth rate (mm/day) and aflatoxin B1 (AFB1) and fumonisin B1 (FB1) production of Aspergillus flavus (AF01) and Fusarium proliferatum (FP01) isolates, respectively was determined at optimum water activities (0.95 and 0.99 aw) and temperatures (25, 30 and 35 °C) on paddy and polished rice grains. The results showed that the growth rate, AFB1 and FB1 production of all the fungal isolates decreased with an increase in CO concentrations on both matrices. AF01 and FP01 failed to grow under all conditions on paddy at 50 % of CO concentration whereas both fungi were completely inhibited (No Growth-NG) at 70 % of CO on polished rice. Regarding mycotoxin production, 30 % of CO concentrations could inhibit AFB1 and FB1 production in both matrices (No Detection-ND). In this study, the production of mycotoxins was significantly influenced by cinnamon oil compared to the growth of both fungi. These results indicated the promising potential of CO in improving the quality of rice preservation in post-harvest; however, further investigations should be evaluated on the effects on the qualitative characteristics of grains. Especially, the prospective application of CO in rice storage in industry scales to mitigate mycotoxin contamination need also to be further researched. Moreover, collaboration between researchers, agricultural experts, and food industry should be set up to achieve effective and sustainable strategies for preserving rice.

Arsenic and heavy metal contents in white rice samples from rainfed paddy fields in Yangon division, Myanmar-Natural background levels?

The presence of potentially toxic metal(loid)s (As, Pb, Cd, Cr, Mn, Fe, Zn, Cu, Ni, Mo and Co) in 120 white (polished) rice grains (Oryza sativa; 2017 or earlier crop) purchased from farmers in the five most agriculturally active townships near Yangon in the eastern edge on Ayeyarwady Delta was determined by triple quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ). Their total-As and Ni concentrations (0.16 mg/kg, 0.39 mg/kg) were around the worldwide average literature values from a heavy metal non-contaminated area of intermediate to acidic (non-mafic) composition. Their Pb, Cd, and Cr mean concentrations (0.010, 0.0056, and 0.056 mg/kg, respectively) were lower than the maximum allowable levels by over one magnitude, reaching the concentration ranges comparable to the lowest level in the literature values. This study's natural background levels were explained by a negligible influence of human, mining and industrial activities in this area, and probably genotype effect, which remains to be examined by the associated paddy soil analysis. Health risks associated with rice consumption (ca. 0.5 kg/day) by the inhabitants were estimated, assuming that inorganic arsenic was 30% of the total. Arsenic was the main contributor (30%) to the total value of the non-cancer risk (HI) of each element, which was 4.5 times the reference value (< 1), followed by Mn, Zn, Cu, Mo, Co and Ni (15-7%) and Pb, Cd, Cr and Fe (below 4%). The total cancer risk (TCR) for each element was around 17 times higher than the upper limit of cancer risk for an environmental carcinogen (< 0.0001): Nickel accounts for two-thirds of the contribution (66%), followed by Cd (16%) and As (13%). This study suggests that consumers of Yangon rice from paddy fields without groundwater irrigation may need to be concerned about the potential risk of Ni intake besides arsenic.

Processing affects (decreases or increases) metabolites, flavonoids, black rice pigment, and total antioxidant capacity of purple glutinous rice grains.

The objective of this study was to understand the effects of processing on metabolites, flavonoids, black rice pigments and total antioxidant capacity of purple grains. The biochemical indicators and metabolites were determined before and after processing of purple grains. The results showed that the total antioxidant capacity, total phenol (TP), flavonoid (PD), oligomeric proanthocyanidin (OPC), ascorbic acid (AsA), cyanidin-3-O-glucoside (C3OG), peonidin 3-glucoside (P3G) contents of purple grains were greatly decreased after brown rice grains were processed into polished rice grains. The TP, PD, OPC, AsA, C3OG, and P3G of Yangzinuo No.1 brown rice (YZN1_B) or polished rice grains (YZN1_H) were higher than those of Yangzinuo No.2 brown rice (YZN2_B) or polished rice grains (YZN2_H). 154 differential metabolites (DMs) were identified between YZN1_B and YZN1_H. 52 DMs were identified between YZN2_B and YZN2_H. Citric acid and isocyanate are key metabolites affected during processing and have good correlations with various biochemical indicators.

Efficacy of three plant oils against Sitophilus oryzae L. (Coleoptera: Curculionidae) on stored polished and local rice

Oil extracts from three tropical plants, Annona muricata, Moringa oleifera and Senna alata commonly used medicinally in treating various ailments were tested in the laboratory under constant conditions at 30+2 °C and 60-65 % relative humidity for their ability to protect local and polished rice grains against Sitophilus oryzae, a major pest in storage. Doses at 0.0, 0.5 and 1.0 ml/100 g rice grains were separately applied for assessment of adult mortality in the laboratory for 3 days. Parameters assessed were single effect, combined effects and combined cumulative effects of plant oils on mortality of S. oryzae on local and polished rice. The experiment was laid out in a Completely Randomized Design (CRD) with each treatment replicated four times. The results showed that A. muricata at 1.0 ml and M. oleifera at 0.5 and 1.0 ml each recorded higher (p

Influence of structural changes of brown rice by precise polishing on in vitro starch digestibility of cooked rice grain

The relationship between the tissue structure of rice grains prepared using stepwise degrees of polishing (DOP) and starch digestibility was investigated in this study. Brown rice grains (Oryza sativa L. cv. Koshihikari) was precisely polished to 1, 3, 5, 7, and 10% (w/w) of the original weight using a pressure-type rice polisher and then cooked using a standardized cooking procedure. Although the total starch content of cooked grains had a significant tendency to increase with an increase in the DOP (77.64–84.16% db), the resistant starch content was constant between the cooked grains with different DOP (0.32–0.43% db). Cooked brown rice grains had significantly lower starch hydrolysis (65.68 vs. 89.74–96.17%) and estimated glycemic index (72.50 vs. 84.95–92.90) than polished grains after in vitro gastro-small intestinal digestion. The results revealed that starch digestibility of cooked brown rice grains was not proportional to DOP. The bran layer remained intact and covered a smaller area of the endosperm as DOP increased. In conclusion, the starch digestibility of cooked stepwise polished rice grains was affected by the bran layer on the outermost surface, which was equivalent to 1% of the weight of the brown rice grains. However, it was not affected by the ratio of the bran layer remaining on the cooked grain surface. The results of this study could contribute to the development of new agricultural machinery products that solve problems related to the control of GI of rice and rice products.

Irrigation and phosphorous fertilization management to minimize rice grain arsenic content

This research sought to minimize inorganic arsenic levels in polished rice grain by using different irrigation and phosphorous fertilization practices while also maintaining crop yield and water productivity. Two experiments were conducted during seasons 2018–2019 and 2019–2020 using a split-plot design with three blocks, five irrigation treatments (main-plots) and two phosphorous levels (sub-plots). Irrigation treatments consisted of a traditional continuous flood (CF) control and four alternatives irrigation techniques with one or two drying events during the irrigation cycle. The phosphorous fertilization levels investigated were an unfertilized control (0 kg P2O5 ha−1) and the recommended fertilization level of 50 kg P2O5 ha−1. Soil pH and redox potentials were measured in each treatment. Strategically-timed, low severity drying events were effective at achieving aerobic soil conditions, resulting in Eh values over 50 mV. The alternative irrigation treatment with two drying events, implemented at panicle initiation and full flowering, was the most effective in reducing inorganic arsenic in grain without affecting grain yield or the amount of irrigation water applied. This irrigation technique could be considered as an alternative management to the traditional continuous flooded to reach minimal inorganic arsenic accumulation in grain in order to attend special quality standards or specific market requirements. Accumulated inorganic arsenic in grain was below international maximum levels in all analyzed samples, with an average value of 0.084 mg kg−1.

Widespread Occurrence of the Highly Toxic Dimethylated Monothioarsenate (DMMTA) in Rice Globally.

Arsenic (As) accumulation in rice is of global concern for human health and international trade. Rice is typically reported to contain inorganic As (iAs) and dimethylated arsenate (DMA), with current food guidelines limiting toxic iAs but not less-toxic DMA. Here, we show that the highly toxic dimethylated monothioarsenate (DMMTA) is also found in rice worldwide and has been unknowingly determined as less-toxic DMA by previous routine analytical methods. Using enzymatic extraction followed by high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) analysis with a C18 column, DMMTA was detected in rice grains (n = 103) from a field survey from China and in polished rice grains (n = 140) from a global market-basket survey. Concentration ranged from <0.20 to 34.8 μg/kg (median 10.3 μg/kg), accounting for 0 to 21% of total As. A strong linear correlation was observed in all rice samples between DMA and DMMTA (being 30 ± 8% of DMA) concentrations. This robust relationship allows an estimation of DMMTA in rice grains from the DMA data reported in previous market-basket surveys, showing a general global geographical pattern with DMMTA concentration increasing from the equator toward high-latitude regions. Based on the global occurrence and potential high toxicity, DMMTA in rice should be considered in health risk assessments and for setting food regulations.

Deep learning based high-throughput phenotyping of chalkiness in rice exposed to high night temperature

BackgroundRice is a major staple food crop for more than half the world’s population. As the global population is expected to reach 9.7 billion by 2050, increasing the production of high-quality rice is needed to meet the anticipated increased demand. However, global environmental changes, especially increasing temperatures, can affect grain yield and quality. Heat stress is one of the major causes of an increased proportion of chalkiness in rice, which compromises quality and reduces the market value. Researchers have identified 140 quantitative trait loci linked to chalkiness mapped across 12 chromosomes of the rice genome. However, the available genetic information acquired by employing advances in genetics has not been adequately exploited due to a lack of a reliable, rapid and high-throughput phenotyping tool to capture chalkiness. To derive extensive benefit from the genetic progress achieved, tools that facilitate high-throughput phenotyping of rice chalkiness are needed.ResultsWe use a fully automated approach based on convolutional neural networks (CNNs) and Gradient-weighted Class Activation Mapping (Grad-CAM) to detect chalkiness in rice grain images. Specifically, we train a CNN model to distinguish between chalky and non-chalky grains and subsequently use Grad-CAM to identify the area of a grain that is indicative of the chalky class. The area identified by the Grad-CAM approach takes the form of a smooth heatmap that can be used to quantify the degree of chalkiness. Experimental results on both polished and unpolished rice grains using standard instance classification and segmentation metrics have shown that Grad-CAM can accurately identify chalky grains and detect the chalkiness area.ConclusionsWe have successfully demonstrated the application of a Grad-CAM based tool to accurately capture high night temperature induced chalkiness in rice. The models trained will be made publicly available. They are easy-to-use, scalable and can be readily incorporated into ongoing rice breeding programs, without rice researchers requiring computer science or machine learning expertise.

Regional variability of arsenic content in Uruguayan polished rice

Characterization of the country internal variability of arsenic (As) accumulation in rice grain across different rice production regions is very important in order to analyze its compliance with international and regional limits. A robust sampling study scheme (n = 150 samples) was performed to determine total arsenic (tAs) and inorganic (iAs) levels from polished rice grain covering all rice producing regions along two growing seasons.The mean and median concentration of tAs were 0.178 mg kg-1 and 0.147 mg kg-1, with a minimum and maximum value of 0.015 mg kg−1 and 0.629 mg kg−1, respectively and a coefficient of variation of 63.6%. The mean and median concentration of iAs were 0.062 mg kg−1 and 0.055 mg kg−1 respectively ranging from 0.005 mg kg−1 up to a maximum of 0.195 mg kg−1 and a coefficient of variation of 51.5%. A moderate correlation was revealed within iAs and tAs. Levels of iAs in all of the samples were below the international limits of 0.2 mg kg−1 according to the international limits for human health by the Codex Alimentarius (FAO and WHO, 2019).Rice fields cultivated on soils originated from igneous geological material reported lower arsenic levels accumulated in rice grain in relation to sedimentary soils. Japonica cultivars presented significantly lower tAs and iAs concentrations than Indica ones (p = 0.0121 and p < 0.0001; respectively).Consumption of rice by male and female adults in Uruguay is safe according to its level of annual consumption and based on the mean iAs levels determined in this study.

Rice Compounds with Impact on Diabetes Control.

Rice is one of the most cultivated and consumed cereals worldwide. It is composed of starch, which is an important source of diet energy, hypoallergenic proteins, and other bioactive compounds with known nutritional functionalities. Noteworthy is that the rice bran (outer layer of rice grains), a side-stream product of the rice milling process, has a higher content of bioactive compounds than white rice (polished rice grains). Bran functional ingredients such as γ-oryzanol, phytic acid, ferulic acid, γ-aminobutyric acid, tocopherols, and tocotrienols (vitamin E) have been linked to several health benefits. In this study, we reviewed the effects of rice glycemic index, macronutrients, and bioactive compounds on the pathological mechanisms associated with diabetes, identifying the rice compounds potentially exerting protective activities towards disease control. The effects of starch, proteins, and bran bioactive compounds for diabetic control were reviewed and provide important insights about the nutritional quality of rice-based foods.

Geographical Differentiation of Hom Mali Rice Cultivated in Different Regions of Thailand Using FTIR-ATR and NIR Spectroscopy

Although Hom Mali rice is considered the highest quality rice in Thailand, it is susceptible to adulteration and substitution. There is a need for rapid, low-cost and efficient analytical techniques for monitoring the authenticity and geographical origin of Thai Hom Mali rice. In this study, two infrared spectroscopy techniques, Fourier-transform infrared spectroscopy with attenuated total reflection (FTIR-ATR) and near-infrared (NIR) spectroscopy, were applied and compared for the differentiation of Thai Hom Mali rice from two geographical regions over two production years. The Orthogonal Projections to Latent Structures Discriminant Analysis (OPLS-DA) model, built using spectral data from the benchtop FTIR-ATR, achieved 96.97% and 100% correct classification of the test dataset for each of the production years, respectively. The OPLS-DA model, built using spectral data from the portable handheld NIR, achieved 84.85% and 86.96% correct classification of the test dataset for each of the production years, respectively. Direct NIR analysis of the polished rice grains (i.e., no sample preparation) was determined as reliable for analysis of ground rice samples. FTIR-ATR and NIR spectroscopic analysis both have significant potential as screening tools for the rapid detection of fraud issues related to the geographical origin of Thai Hom Mali rice.

Effect of Milling and Parboiling Processes on Arsenic Species Distribution in Rice Grains

This study identified the role of milling and parboiling on arsenic (As) content and its species in large numbers of rice samples. Total As contents were 108±33μg/kg in polished rice grains (PR), 159±46μg/kg in unpolished rice grains (UR), 145±42μg/kg in parboiled polished rice grains (PPR) and 145±44μg/kg in parboiled unpolished rice grains (PUR). The percentages of inorganic As (iAs) were 66%±8% in PR and from 72% to 77% in other grain categories. The polishing process reduced the As content in the rice grains, removing outer part of the UR with high amount of As, whereas the parboiling technique transferred the semimetal content within the grain. Total As and iAs contents were not significantly different in UR, PPR and PUR, homogenizing its distribution inside the grains. The results allowed to understand how different operations affect As fate and its chemical forms in grains.

Effects of cultivars and fertilization levels on the quality of rice milling: A diagnosis using near-infrared spectroscopy, X-ray diffraction, and scanning electron microscopy

Cultivars and fertilization levels influence rice productivity and can be associated with grain quality. Thus, it is possible to make decisions regarding the choice of cultivars and application of fertilizer levels based on the type of milling, a necessary post-harvest process that may minimize the nutrient load in the grains and result in loss in quality. This study relates the physicochemical composition and morphological quality of brown and polished milled rice grains, cultivar types, and different levels of soil fertilization using near-infrared spectroscopy analysis, X-ray diffraction and scanning electron microscopy. Statistical tools were used to test the various treatments and identify the relationship between factors and variables. A high fertilization level is related to increasing crude protein composition and starch for cultivar IRGA 431 CL associated with polished rice. However, the combination of cultivar IRGA 424 RI and brown rice demonstrated a higher grain resistance, and different percentages of whole, chalky, and damaged rice. The correlation between ash × crude protein and starch × crude fiber was found to be positive for brown rice and negative for the polished rice. Further, an increase in starch content was inversely proportional to the ash content, whereas an increase in crude protein was inversely proportional to the low-fat content in milled rice. The crystalline characteristics of rice starch were preserved at high fertilization levels associated with polished grains that demonstrated high starch content. Polished grains, however, showed more pores and cavities, and consequently greater permeabilities in the surface. It is recommended that batches of grains produced from cultivar IRGA 431 CL with high levels of fertilization be subjected to polished rice milling to achieve high protein and starch quality. However, grains from cultivar IRGA 424 RI with high levels of fertilization are recommended for brown rice milling owing to the high percentage of physical defects observed.

RNAi-mediated down-regulation of ITPK-2 enhanced inorganic phosphorus and minerals in the transgenic rice

Phytic acid or Myo-inositol hexakisphosphate is an essential compound for the rice plants. It remains in the form of phytate, a mixed salt of different mineral cations, in the seeds. The phytate breaks down during germination and provides the inorganic phosphorus and mineral ions to the seedlings. However, humans do not get the benefit of those essential ions from rice consumption due to the absence of phytase in the gut. We envisaged down-regulating ITPK, the gene behind the phytic acid biosynthesis so that its low amount would facilitate a greater amount of free mineral ions in the endosperm. Since there are six homologues of rice ITPK, we studied their expression in seeds. Additionally, we undertook an in-silico analysis of the homologous proteins. Considering the results, we selected ITPK-2 for its RNAi-mediated embryo-specific down-regulation to obtain the low phytate rice. We obtained a 37% reduction of phytic acid content accompanied by a nearly three-fold enhancement of inorganic phosphorus in the transgenic seeds. Additionally, the iron and zinc content increased in polished rice grains compared to the wild type. The results also showed that reduced phytic acid content did not affect the germination potential and seedling growth of the transgenic rice.

Avoiding Rice-Based Cadmium and Inorganic Arsenic in Infant Diets Through Selection of Products Low in Concentration of These Contaminants

Cadmium in the diet is of concern as it is a renal toxicant and a carcinogen, with a half-life in the body measured in decades. Inorganic arsenic is a chronic carcinogen. For many subpopulations, rice and rice products may be the dominate source of cadmium and inorganic arsenic. In particular, rice porridge, cereal and cake are widely used to feed infants (children < 4.5 years old). In the EU standards for cadmium infant foods in general has been set at 40 μg/kg w.wt., and for inorganic arsenic in rice-based infant foods the standard is 100 μg/kg w.wt.. Here we report cadmium and inorganic arsenic concentrations in rice products marketed for infants, and rice containing products that infants may eat but that are not specifically designated for infants. It was found that while rice-based infant foods conformed to the standards, their non-infant food (generic) analogues did not. Non-infant rice crackers and puffed rice cereals, in particular, had concentrations above these standards for both cadmium and inorganic arsenic. Polished pure rice grain purchased in the UK, but sourced from different countries, was also problematic. Basmati, Italian, Spanish and Thai rice, either exceeded one or the other of the cadmium and inorganic arsenic safety thresholds for infants, or both. Egyptian rice grain was particularly low for both toxins. Therefore, if those responsible for infants want to lower exposure to cadmium and inorganic arsenic, they should stick to foods specifically labeled for infants, or carefully source low cadmium and inorganic arsenic rice-based products that are not specifically labeled as being for infant consumption, or minimize exposure to rice-based foods.

Volatile Organic Compound Based Markers for the Aroma Trait of Rice Grain

A study was conducted to determine the volatile organic compounds (VOCs) associated with rice grain aroma in 37 commonly grown lines within Uganda, as well as elites. The aim of the study was to identify potential volatile biochemical markers, if any, for the rice grain aroma trait. Certified rice seeds were obtained from the Uganda National Crops Resources Research Institute germplasm collection. The seeds were sown into experimental plots, under field conditions and the mature paddy harvested. Polished rice grains were heated to 80 oC and the liberated VOCs subjected to untargeted metabolite analysis using gas chromatography-time-of-flight mass spectrometry. In total, nine functional groups were present; hydrocarbons, alcohols, ketones, aldehydes, N-containing compounds, S-containing compounds, esters, oxygen heterocycles and carboxylic acids. More specifically, 148 VOCs were identified across the 37 rice lines, of which 48 (32.4%) including 2-acetyl-1-pyrroline (2-AP) appeared to elucidate the difference between non-aromatic and aromatic rice. Furthermore, 41 (27.7%) VOCs were found to be significantly correlated with 2-AP abundance, the principle rice aroma compound. Amongst the 41 VOCs, only ten compounds were found to contribute highly towards variation in 2-AP abundance, indicative of their possible modulation roles in regard to rice aroma. Within the ten influential volatiles, three aroma active compounds; toluene, 1-hexanol, 2-ethyl and heptane, 2,2,4,6,6-pentamethyl- were established as the most reliable biochemical surrogates to the rice aroma trait. Thus, the aforementioned compounds may be used in rice breeding programme for enhancing development of the grain aroma trait.

Assessment and source identification of As and Cd contamination in soil and plants in the vicinity of the Nui Phao Mine, Vietnam.

This study investigated the contamination levels and sources of As and Cd vicinity area from Nui Phao mine that is one of the largest tungsten (W) open pit mines in the world. Soil and plant samples were collected from the study area to identify the concentrations of As and Cd using aqua-regia or HNO3 digestion. According to the Vietnamese agricultural soil criteria, all soil samples were contaminated with As and Cd. The distribution of As concentration is related to the distance from the Nui Phao mine. The higher As concentrations were measured in the area close to the mine. However, the Cd distribution in the soil showed a different pattern from As. Enrichment factor and Geoaccumulation Index (Igeo) indicated that As in the soil is derived from the mining activities, while Cd could have other geogenic or anthropogenic sources. The ranges of As and Cd concentration in polished rice grains in the Nui Phao mine area exceeded the CODEX criteria (0.2mg/kg), which indicated extreme contamination. The arsenic concentration between soil and plant samples was determined to be a positive correlation, while the Cd concentration showed a negative correlation, implying that As and Cd have different geochemical behavior based on their sources.