Iodine In Groundwater Research Articles

Factors controlling iodine enrichment in a coastal plain aquifer in the North Jiangsu Yishusi Plain, China

Iodine is an essential micronutrient in the human diet and an appropriate human iodine intake level is important for population health. Excessive iodine intake is often associated with high iodine groundwater which serves as an important drinking water source in many regions. This study aims to identify the source and key hydrogeochemical processes for iodine accumulation and mobility in the groundwaters of the Northern Jiangsu Yishusi Plain. Combined hydrogeochemical and statistical analyses, specifically random forest modeling and factor analysis, were used to explore the mechanisms affecting the spatial distribution of iodine. The concentration of iodine in the investigated groundwaters was found to vary widely and to range between 4.8 and 4750 μg/L, with 48.9% of the total samples (674) exceeding the threshold value of 100 μg/L for toxic exposure, as defined by the Chinese high‑iodine standard guideline. High iodine concentrations are shown to mainly occur in the marine plain and the shallow aquifer associated with the floodplains of the Old Yellow River. The marine or lagoons-facies sediments were identified as the most plausible iodine source. In addition, mixing of groundwater with paleo-seawater might also have played a role in the coastal area. In contrast, the flood sediments of the Old Yellow River are shown to be an unlikely source. However, they serve as a cover layer that favored the development of reducing hydrogeochemical conditions that can trigger iodine mobilization via the reductive dissolution of iron oxides and the degradation of organic matter. Slow groundwater flow rates also appear to favor iodine release from sediments.

GLOBAL ENDOCRINOLOGY: Global perspectives in endocrinology: coverage of iodized salt programs and iodine status in 2020

Iodine deficiency has multiple adverse effects on growth and development. Diets in many countries cannot provide adequate iodine without iodine fortification of salt. In 2020, 124 countries have legislation for mandatory salt iodization and 21 have legislation allowing voluntary iodization. As a result, 88% of the global population uses iodized salt. For population surveys, the urinary iodine concentration (UIC) should be measured and expressed as the median, in μg/L. The quality of available survey data is high: UIC surveys have been done in 152 out of 194 countries in the past 15 years; in 132 countries, the studies were nationally representative. The number of countries with adequate iodine intake has nearly doubled from 67 in 2003 to 118 in 2020. However, 21 countries remain deficient, while 13 countries have excessive intakes, either due to excess groundwater iodine, or over-iodized salt. Iodine programs are reaching the poorest of the poor: of the 15 poorest countries in the world, 10 are iodine sufficient and only 3 (Burundi, Mozambique and Madagascar) remain mild-to-moderately deficient. Nigeria and India have unstable food systems and millions of malnourished children, but both are iodine-sufficient and population coverage with iodized salt is a remarkable 93% in both. Once entrenched, iodine programs are often surprisingly durable even during national crises, for example, war-torn Afghanistan and Yemen are iodine-sufficient. However, the equity of iodized salt programs within countries remains an important issue. In summary, continued support of iodine programs is needed to sustain these remarkable global achievements, and to reach the remaining iodine-deficient countries.

Sources and hydrogeological conditions that cause high iodine concentrations in deep groundwater in the Zhangwei watershed, North China Plain

The sources and primary mechanisms of high iodine concentration in deep groundwater are rarely reported, thereby restricting the development and utilization of the related groundwater resources. To address these issues, 194 deep groundwater samples were collected from the Zhangwei watershed in the North China Plain, China, to analyze their constituents including iodine. Statistics, principal component analysis and hydrological methods were employed to determine the distribution of iodine concentrations and their controlling hydrogeochemical processes. The results show that the iodine concentration ranged from 2 to 446 μg/L and generally increased along the groundwater flow direction. Three zones with high iodine concentration (> 20 μg/L) were delineated as the alluvial–proluvial plain (Zone A, average 70 μg/L), alluvial–lake plain (Zone B, average 83 μg/L) and coastal plain (Zone C, average 199 μg/L), respectively. In Zone A, aquifer minerals weathering probably releases iodate ions into groundwater. The iodate is reduced with nitrate as the electron acceptor of iodine and transported with the precipitation infiltrating through the vadose zone to recharge groundwater, resulting in increasing the groundwater iodine concentration. In Zone B, the iodine concentrations depend on the contents of the organic matter, clay minerals, and iron aluminum oxide in the alluvial–lake sediments, due to that the deeply buried organic matter is rich in iodine which is released into groundwater through the biodegradation of organic matter, In Zone C, the iodine is probably derived from the sediments which were deposited in Quaternary marine transgression events, and its enrichment was controlled by the strong reduction condition of the deep aquifers. In one word, the iodine sources and hydrogeological conditions determined the high iodine concentrations of deep groundwater in the studied watershed. These findings can provide foundation for further insight into the high iodine concentration of deep groundwater in other hydrogeological units of the North China Plain and other similar units over the world, thereby ensuring drinking groundwater safety.

Iodine enrichment and the underlying mechanism in deep groundwater in the Cangzhou Region, North China.

The lack of information on the origin and behavior of iodine in deep groundwater restricts the development and use of groundwater resources. To address this issue, the Cangzhou region in the eastern North China Plain (NCP) was selected for a case study. In total, 296 deep groundwater samples were collected, their iodine concentrations were determined, and the distribution characteristics of iodine concentrations were analyzed. Iodine concentrations ranged from < 0.002 to 1.22 mg/L, with a mean of 0.19 mg/L; 42% of the samples had high iodine concentrations. The levels were higher in the east than in the west, and most of the samples with high iodine concentrations were obtained from sites east of the boundary between the Cangxian uplift and the Huanghua depression. The weathering and dissolution of iodine-bearing minerals and the leaching of marine sediments can facilitate iodine enrichment. In the Cangxian uplift, iodine was mainly a result of the conversion of organic iodine, while in the Huanghua depression, iodine enrichment was a factor of the conversion of IO3-. Overall, the main factors for the enrichment of iodine are the sedimentary environmental and the hydrodynamic conditions. Our results provide a theoretical basis to understand the occurrence of high iodine concentrations in deep groundwater.

Thyroid Dysfunction among School-Aged Children due to Chronically Excessive Iodine Groundwater, Central Java, Indonesia

Thyroid Dysfunction among School-Aged Children due to Chronically Excessive Iodine Groundwater, Central Java, Indonesia

Natural organic matter-enhanced transportation of iodine in groundwater in the Datong Basin: Impact of irrigation activities

Local residents in the Datong Basin of northern China are exposed to groundwater with elevated iodine concentrations. Natural organic matter (NOM) has been linked to the heterogeneous distribution of elevated iodine in groundwater used for irrigation purposes, but little is known about the effects of hydrologic fluctuations and NOM characteristics on the transport and enrichment of iodine in the groundwater. Cl/Br molar ratios in Datong Basin groundwater range widely from 133 to 2099. A rapid increase in Cl/Br molar ratio with increasing Cl content indicates hydrologic fluctuations from the upper groundwater to the deeper aquifer due to large-scale irrigation activities in the Basin. A two end-member model of groundwater δ2H and δ18O values suggests the contribution of upper water recharging groundwater ranges from 20.7 to 49.5%. This vertical recharge process predominantly controls iodine enrichment and distribution in the groundwater. Additionally, the correlation between DOC concentration and δ18O signatures indicates considerable fresh organic matter is imported into the aquifer during the vertical recharge process. Iodine mobilization is likely promoted by young carbon transported to the deeper aquifer in the organo‑iodine form. Excitation-emission matrix (EEM) results indicate humic-like substances dominate NOM in the groundwater. Evidence from a PARAFAC model suggests organic matter in groundwater samples is associated with microbially-mediated degradation processes in an anaerobic environment. The drawdown migration of organic matter from the upper soil/sediments or surface could provide an extra energy source that promotes microbial activity. Buried sedimentary iodine coupled with anaerobic microbial respiration of subsurface organic carbon within the aquifer could lead to the release of iodine into the groundwater. These findings pave the way for a more comprehensive assessment of the susceptibility of drinking water aquifers, thereby supporting the management of groundwater resources.

Microbial Contribution to Iodine Speciation in Hanford's Central Plateau Groundwater: Iodide Oxidation

A waste product from plutonium production at Hanford, the radioisotope iodine-129 (129I), is an environmental concern due to its long half-life, mobility, and hazardous potential to humans through bioaccumulation in the thyroid gland. Consequently, understanding the biological mechanisms and contributors to iodine speciation is important in order to increase our knowledge of iodine mobility and the overall risk to human health and the environment, and to evaluate remediation strategies for contaminated areas, as current remediation methods are insufficient and unsustainable. Although iodide (I-) is thermodynamically favored in the geological support material based on existing pH and Eh ranges at the Hanford Site, the dominant species of iodine found in groundwater and the vadose zone is iodate (IO3-). While microbial activity has been shown to catalyze the oxidation of I- to IO3-, this process has not been demonstrated by naturally occurring microbes found in the subsurface at the Hanford Site. Four microbial isolates enriched from Hanford groundwater were shown to oxidize I- to molecular iodine (I2) when grown on sugars and organic acids. Glucose proved to be the best substrate for growth, enzyme production, and I- oxidation. Multi-copper oxidases, such as laccase, have been shown to oxidize I-, and were produced during growth on glucose, xylose, and lactate. These results indicate that bacteria may play a significant role in groundwater iodine speciation (dominated by IO3-), as this form is not thermodynamically favorable and would not exist without transformation.

Spatial distribution and origin of shallow groundwater iodide in a rapidly urbanized delta: A case study of the Pearl River Delta

Iodine-rich groundwater is a cause for concern because it is harmful to human health, and determining the sources of groundwater iodine in coastal urbanized areas is complicated. This study aims to delineate the spatial distribution of groundwater iodide in various shallow and unconfined aquifers, as well as in areas with different urbanization levels in the Pearl River Delta (PRD), and to identify the origins of iodide-rich (>0.08 mg/L) groundwater in this region. Approximately 400 groundwater samples, 10 surface water samples, and 9 leachate samples were collected, and a total of 17 chemicals were analyzed. The result showed that iodide-rich groundwater was present in 13.95% of shallow granular aquifers and 6.82% of shallow fissured aquifers; however, it was not present in karst aquifers. In shallow granular aquifers, the proportions of iodide-rich groundwater in areas with different urbanization levels were similar. On the other hand, in shallow fissured aquifers, iodide-rich groundwater mostly appeared in urbanized areas, and its proportion was more than three times that of non-urbanized areas; however, it was not present in peri-urban areas. The reductive dissolution of iodine-loaded Fe/Mn (oxy)hydroxides and decomposition of iodine-rich organic matter in sediments were likely the main sources of iodide-rich groundwater in shallow granular aquifers. Urbanization accompanied by wastewater leakage was also a significant source for iodide-rich groundwater in granular aquifers of urbanized areas. In contrast, the degradation of organic matter in carbonate-rich rocks and urbanization accompanied by leakage of reductive sewage were most likely responsible for the occurrence of iodide-rich groundwater in shallow fissured aquifers. The leakage of landfill leachate was also a significant source for iodide-rich groundwater in the fissured aquifers of non-urbanized areas.

Hydrogeochemical Characteristics and Health Effects of Iodine in Groundwater in Wei River Basin

Existing studies show that drinking high-iodine or low-iodine groundwater on a long-term basis may cause goiter and other health problems. However, currently there is a lack of systematic research on the distribution, formation and health effects of iodine in groundwater at the basin scale. Taking the Wei River Basin in the Loess Plateau as a typical study area, this paper used hydrogeological surveys, sample collection, multivariate statistical analysis, health effect evaluations, and other methods, and found that iodine content in groundwater in 60.3% of the region poses potential risks to human health. Groundwater recharge areas were iodine-deficient, mainly located on the upstream Loess Plateau of the Wei River Basin in the vicinity of the Liupan Mountain watershed, and at the piedmont of the Qinling Mountains. Groundwater was low mineralization, neutral, and low-F bicarbonate, and was controlled by the weathering and dissolution of silicate minerals and evaporites, the dissolution and precipitation of carbonates, and active water circulation conditions. Iodine-deficient endemic goiter had a potential incidence of 5–38% in these areas. Groundwater runoff areas had suitable groundwater iodine content, and the groundwater hydrochemical type was dominated by HCO3–Ca, HCO3–Na, and HCO3·SO4–Na type water. The mineralization degree was modest and the I− content distribution of suitable iodine content areas was controlled by relatively active water circulation conditions. Groundwater discharge areas were high-iodine groundwater areas, where the groundwater hydrochemical type was dominated by meta-alkaline and alkaline HCO3·SO4, SO4·Cl, and Cl·SO4 type water, and controlled by the evaporation–concentration of shallow groundwater, the biodegradation of enriched organic matter, and the competitive adsorption of HCO3− and I−. Here iodine-excess endemic goiter had a potential incidence of 5–100%. Considering the results from the study area, this paper recommends that the groundwater iodine safety range for endemic goiter be set to 10.0–300.0 μg/L.

Effects of depositional environment and organic matter degradation on the enrichment and mobilization of iodine in the groundwater of the North China Plain

Groundwater iodine has direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin. However, little is known about enrichment and mobilization mechanisms of groundwater iodine in the North China Plain (NCP). Geochemistry, inorganic/organic carbon isotope and biomarker of groundwater and sediment samples were studied to reveal the effects of depositional environment and organic matter (OM) degradation on the generation of high iodine groundwater (>100 μg/L) in NCP. Results showed that groundwater iodine had a range of 7.2–800 μg/L and was increasing with increase in HCO3 concentration and decrease in groundwater δ13CDIC value, indicating the potential effects of microbial activity on the elevation of groundwater iodine. Sediments iodine ranged from 0.03 to 2.54 μg/g and higher contents occurred under the oxidizing depositional environment (higher Pr/Ph ratios). Biomarker analysis indicated that the marine iodine-rich OM is considered as the main source of groundwater iodine, which is prone to be released into groundwater by the microbial degradation under the reducing conditions. The hypothesis was evidenced by the 13Corg, 13CDIC and 3-D excitation emission matrices of groundwater. These results suggest that carbon-related biogeochemical cycling and redox condition are important in the enrichment and mobilization of iodine in groundwater system.

Impacts of sediment compaction on iodine enrichment in deep aquifers of the North China Plain

To understand the effects of large-scale sediment compaction on iodine enrichment in the groundwater system of the North China Plain (NCP), hydrogeochemical and isotope (2H, 18O and 87Sr/86Sr) geochemical features of groundwater, seawater and pore water of the deep aquifer sediments were characterized. Groundwater iodine concentration ranged from 5.8 to 1110 μg/L and approximately 80% of groundwater samples have iodine concentration more than 100 μg/L. High iodine groundwater (>100 μg/L) is mainly distributed in the Bohai bay area where serious land subsidence occurs. The sediments deposited during several events of marine transgression are considered as the main source of groundwater iodine. The pore solution compacted from the clayey sediments has a iodine concentration up to 830 μg/L, indicating that marine source iodine was stored in the clayey layers. The hydrogen and oxygen isotope signatures of groundwater show that the groundwater from NCP is mainly recharged by precipitation and the pore water from sediment compaction due to intense land subsidence. The Cl/Br molar ratio and 87Sr/86Sr signatures of groundwater and sediment pore water further suggest the effects of mixing with compaction-released pore solution on the hydrochemical evolution of high iodine groundwater. Based on groundwater δ2H, Cl concentration and 87Sr/86Sr, the results of two end-members mixing model calculation indicate that the compaction-released pore solution contributes approximately 49.1–68.9% iodine to high iodine groundwater, and the iodine from compaction-released pore solution ranges between 407 and 572 μg/L. The results of this study therefore suggest that the compaction of clayey sediments can be a major hydrogeological process controlling the genesis of high iodine groundwater in deep aquifers at NCP.

Maximising benefits and minimising adverse effects of micronutrient interventions in low- and middle-income countries.

Micronutrient deficiencies are widespread and disproportionately affect women and children in low- and middle-income countries (LMIC). Among various interventions, food fortification and supplementation with micronutrients have been proven to be cost-effective. The aim of the present paper is to review existing literature to assess risks of excessive intake in LMIC to then highlight programmatic changes required to maximise benefits of micronutrient interventions while minimising risks of adverse effects. While very few LMIC have national food consumption surveys that can inform fortification programmes, many more are implementing mandatory fortification programmes. The risks of inadequate micronutrient intakes were common, but risks of excessive intakes were also present for iodine, vitamin A, folic acid and iron. Excessive salt consumption, high concentrations of iodine in ground-water and excessive levels of iodisation were linked with excessive iodine intake. For vitamin A, overlapping interventions were the main risk for excessive intake; whereas for iron, contamination with iron from soil and screw-wares of millers and high iron concentration in drinking-water increased the risk of excessive intake, which could be further exacerbated with fortification. Before implementing micronutrient interventions, adherence to the basic principles of documenting evidence confirming that the deficiency in question exists and that fortification will correct this deficiency is needed. This can be supported with dietary intake assessments and biochemical screening that help diagnose nutrient deficiencies. Targeting micronutrient interventions, although programmatically challenging, should be considered whenever possible. Moreover, closer monitoring of appropriate fortification of foods and overlapping interventions is needed.

Factors influencing the distribution of arsenic, fluorine and iodine in shallow groundwater in the oasis zone in the southern margin of the Tarim Basin in Xinjiang, P. R. China

Test results on 302 shallow groundwater samples in an oasis zone in the southern margin of the Tarim Basin in Xinjiang were collected and analysed for a large number of chemical parameters and subjected to mathematical statistics methods. Results show that groundwater with high arsenic, fluorine and iodine concentrations were mainly distributed in the Minfeng County in the central part of the study area. Shallow groundwater in the southern margin of the entire Tarim Basin generally had high fluorine concentrations. The distribution of arsenic and fluorine in groundwater were similar. Intensive evaporation under the arid climatatic condition was an important factor for the enrichment of arsenic, fluorine and iodine in groundwater.

Iodine content in groundwater of North Eastern Morocco and its relation with the incidence of goiter

Abstract Iodine in water has been used as an indicator of the ‘iodine status’ of an area, and it has been suggested that a low iodine content in drinking water is a contributing factor to the onset of Iodine Deficiency Disorders, which the most visible manifestation is goiter. The aim of the present study was to evaluate the importance of groundwater iodine content for the regional differences in goiter frequency observed in rural areas in the North Eastern Morocco where groundwater is the main source of drinking water. Water samples from 9 wells and 4 springs were collected and analyzed. Concentrations of iodine varies from 6.43µg/L to 143.8µg/L. the content was high in wells near the Mediterranean Sea (Bouareg: 115.9µg/L and Laatamna: 143.8µg/L), and the lowest values were in general noted in springs (mean 10.28µg/L). When only well waters were considered, Guenfouda showed a lowest value of iodine (14.6µg/L). This result may, in part, explain why goiter frequency is higher in this area.In order to understand the distribution of iodine and the controlling factors in groundwater from the North Eastern Morocco, hydrochemical study was conducted. Distance to the Mediterranean sea associated with topography, is probably the main explanation for this distribution and hence, the regional differences in goiter frequency observed in this area. The results in this investigation suggest the need to update data on iodine deficiency in the North Eastern Morocco and to recommend possible remediation strategies.

Effect of Excess Iodine Intake from Iodized Salt and/or Groundwater Iodine on Thyroid Function in Nonpregnant and Pregnant Women, Infants, and Children: A Multicenter Study in East Africa.

Acute excess iodine intake can damage the thyroid, but the effects of chronic excess iodine intake are uncertain. Few data exist for pregnant and lactating women and infants exposed to excessive iodine intake. This was a multicenter cross-sectional study. At study sites in rural Kenya and urban Tanzania previously reporting iodine excess in children, urinary iodine concentration (UIC), thyrotropin, total thyroxine, and thyroglobulin (Tg) were measured in school-age children (SAC), women of reproductive age, pregnant (PW) and lactating women, and breast-feeding and weaning infants. In a national study in Djibouti, UIC was measured in SAC and PW. At all sites, daily iodine intake was estimated based on UIC, and iodine concentration was measured in household salt and drinking water. The total sample size was 4636: 1390, 2048, and 1198 subjects from Kenya, Tanzania, and Djibouti, respectively. In Kenya and Tanzania: (i) median UIC was well above thresholds for adequate iodine nutrition in all groups and exceeded the threshold for excess iodine intake in SAC; (ii) iodine concentrations >40 mg of iodine/kg were found in approximately 55% of household salt samples; (iii) iodine concentrations ≥10 μg/L were detected in 9% of drinking water samples; (iv) Tg was elevated in all population groups, but the prevalence of thyroid disorders was negligible, except that 5-12% of women of reproductive age had subclinical hyperthyroidism and 10-15% of PW were hypothyroxinemic. In Djibouti: (i) the median UIC was 335 μg/L (interquartile range [IQR] = 216-493 μg/L) in SAC and 265 μg/L (IQR = 168-449 μg/L) in PW; (ii) only 1.6% of Djibouti salt samples (n = 1200) were adequately iodized (>15 mg/kg); (iii) the median iodine concentration in drinking water was 92 μg/L (IQR = 37-158 μg/L; n = 77). In all countries, UIC was not significantly correlated with salt or water iodine concentrations. Although iodine intake was excessive and Tg concentrations were elevated, there was little impact on thyroid function. Chronic excess iodine intake thus appears to be well tolerated by women, infants, and children. However, such high iodine intake is unnecessary and should be avoided. Careful evaluation of contributions from both iodized salt and groundwater iodine is recommended before any review of iodization policy is considered.

Controls on the spatial distribution of iodine in groundwater in the Hebei Plain, China.

In the Hebei Plain of North China, 70% of the inhabitants depend on groundwater for drinking water. Little is known regarding high-iodine concentrations in groundwater because there have been few systematic studies on high levels of iodine in groundwater in this region. To help identify the mechanisms that control the spatial distribution of iodine in groundwater, 61 samples of shallow groundwater and 161 samples of deep groundwater were collected along a sample section from Taihang Mountain to the Bo Sea. There were four pockets of high-iodine concentrations along the sample section. As the groundwater depth increased, the ratio of undetected iodine decreased, and the ratio of high-iodine concentrations increased. The high-iodine concentrations in the groundwater reflect the geological and sedimentary settings, and were mainly controlled by pH and Eh. Iodine concentrations were particularly high when the pH was between 7.3 and 8.5, and there was an inflection point at 150μg/L in the curve of the relationship between iodine concentrations and Eh.

Iodine Intake Estimation from the Consumption of Instant Noodles, Drinking Water and Household Salt in Indonesia.

The objective of this study was to assess the contribution of iodine intake from iodised household salt, iodised salt in instant noodles, and iodine in ground water in five regions of Indonesia. Secondary data analysis was performed using the 2013 Primary Health Research Survey, the 2014 Total Diet Study, and data from food industry research. Iodine intake was estimated among 2719 children, 10–12 years of age (SAC), 13,233 women of reproductive age (WRA), and 578 pregnant women (PW). Combined estimated iodine intake from the three stated sources met 78%, 70%, and 41% of iodine requirements for SAC, WRA and PW, respectively. Household salt iodine contributed about half of the iodine requirements for SAC (49%) and WRA (48%) and a quarter for PW (28%). The following variations were found: for population group, the percentage of estimated dietary iodine requirements met by instant noodle consumption was significantly higher among SAC; for region, estimated iodine intake was significantly higher from ground water for WRA in Java, and from household salt for SAC and WRA in Kalimantan and Java; and for household socio-economic status (SES), iodine intake from household salt was significantly higher in the highest SES households. Enforcement of clear implementing regulations for iodisation of household and food industry salt will promote optimal iodine intake among all population groups with different diets.

Kajian Kandungan Fe dalam Air Tanah Terhadap Kadar Ekskresi Yodium dalam Urin pada Anak Sekolah di Desa Cerme Kecamatan Panjatan Kabupaten Kulon Progo

Background : IDD problem is a serious problem, 33% of districts in Indonesia are endemic, 21% of endemic mild, moderate endemic 5% and 7% by weight endemic. Urine Iodine Excretion (EYU) illustrates the iodine intake of a person, because 90% of the iodine that enter the body are excreted through the urine. Blocking agents are substances certain minerals such as iron, manganese and calcium, which can bind iodine in groundwater.&#x0D; Objectives : This study aims to determine the relationship of Fe content in ground water sources against EYU levels in school children in the village of the District Cerme Panjatan Kulon Progo.&#x0D; Methods : An observational analytic research with cross sectional design. Data collection is done in May - June 2015. Location research Elementary School Cerme, District Panjatan Kulon Progo. The subjects of the study as many as 34 children in elementary school classroom Cerme 3, 4 and 5 were taken by simple random sampling. Well water and urine samples taken students then tested the iron in the Central Health Laboratory test Yogyakarta and iodine in urine in Magelang BP2GAKY Laboratory. Data analysis using Spearman Range test with significancy level : 0.05.&#x0D; Result : Fe content in the ground water is below the normal threshold is &lt;0.3 mg / L. While levels EYU school children who are under the optimal level of 5.9%, the optimal level of 32.4%, and the optimum levels above 61.8% (optimal: 100 - 199μg / L).&#x0D; Conclusion : There was no significant relationship between the Fe content in groundwater with levels of EYU in school children in District Panjatan Kulon Progo (p = 0.447).&#x0D; &#x0D; Keywords: Fe, EYU

Iodine in major Danish aquifers

Iodine in groundwater can have direct importance for human dietary iodine intake in areas where drinking water is of groundwater origin, as in Denmark. Knowledge on the sources and processes for the varying iodine concentrations in groundwater is of utmost importance for understanding the variation in iodine intake of the population via drinking water. The aim of this study was to characterize groundwater with elevated iodine concentrations and to investigate the sources and processes controlling natural iodine speciation and concentration at four study sites in Denmark with postglacial sandy, Quaternary sandy, and Cretaceous limestone aquifers. Analyses included iodide (I−), iodate (IO3 −), total iodine (TI), major ions, and stable H and O isotopes. Dissolved organic iodine (DOI) was calculated by subtracting I− and IO− 3 from TI. A diagram of stable δ18O and δ2H isotopes in Danish groundwater was compiled in order to interpret the groundwater iodine geochemistry. Groundwater had TI concentrations from 5 to 14,500 µg/L. Iodine speciation reflected the prevailing neutral to alkaline and reduced conditions at the investigated sites with domination of I− and DOI correlated with dissolved organic carbon. We found three different explanations for elevated TI concentrations at the four Danish sites: (1) leaching from soil enriched in iodine due to atmospheric deposition and proximity to the sea, (2) influence from the marine origin of the aquifer sediment due to desorption of iodine from iodine-enriched organic matter or minerals, and (3) influence from residual saline water due to upward advective or/and diffusive transport of iodine.

Sorption and speciation of iodine in groundwater system: The roles of organic matter and organic-mineral complexes

Characterizing the properties of main host of iodine in soil/sediment and the geochemical behaviors of iodine species are critical to understand the mechanisms of iodine mobilization in groundwater systems. Four surface soil and six subsurface sediment samples were collected from the iodine-affected area of Datong basin in northern China to conduct batch experiments and to evaluate the effects of NOM and/or organic-mineral complexes on iodide/iodate geochemical behaviors. The results showed that both iodine contents and kf-iodate values had positive correlations with solid TOC contents, implying the potential host of NOM for iodine in soil/sediment samples. The results of chemical removal of easily extracted NOM indicated that the NOM of surface soils is mainly composed of surface embedded organic matter, while sediment NOM mainly occurs in the form of organic-mineral complexes. After the removal of surface sorbed NOM, the decrease in kf-iodate value of treated surface soils indicates that surface sorbed NOM enhances iodate adsorption onto surface soil. By contrast, kf-iodate value increases in several H2O2-treated sediment samples, which was considered to result from exposed rod-like minerals rich in Fe/Al oxyhydroxide/oxides. After chemical removal of organic-mineral complexes, the lowest kf-iodate value for both treated surface soils and sediments suggests the dominant role of organic-mineral complexes on controlling the iodate geochemical behavior. In comparison with iodate, iodide exhibited lower affinities on all (un)treated soil/sediment samples. The understanding of different geochemical behaviors of iodine species helps to explain the occurrence of high iodine groundwater with iodate and iodide as the main species in shallow (oxidizing conditions) and deep (reducing conditions) groundwater.