Soil Se Concentrations Research Articles

Managing high levels of boron and selenium with trace element accumulator crops

Abstract High concentrations of native extractable boron (B) and selenium (Se) found in some soil environments are detrimental to sustainable agriculture in many parts of the western U.S. As part of a strategy to reduce the impact of this problem, greenhouse and field experiments were conducted to study B and Se uptake in the following plant species used for bioremediation: Astragalus incanus L. (no common name), Creeping saltbush (Atriplex semibaccata R. Br. L.), Old Man saltbush (Atriplex nummularia Lindl. L.), Indian mustard (Brassica júncea Czern L.), tall fescue (Festuca arundinacea Schreb. L.), canola (Brassica napus L.), birdsfoot trefoil (Lotus comiculatus L.), and kenaf (Hibiscus cannabi‐nus L.). In Experiment I, all five plant species, especially Indian mustard, accumulated and lowered soil Se concentrations more effectively when grown in selenate‐treated soil than selenite‐treated soil. In Experiment II, plant tissue concentrations of Se and B in Indian mustard increased proportionally to concentrations of Se and B in water culture. In Experiment III, Indian mustard, canola, and tall fescue accumulated and lowered native soil Se and B concentrations when grown under greenhouse conditions. In Experiment IV, Indian mustard accumulated the highest concentration of native soil Se and kenaf accumulated the highest concentration of native soil B under field conditions. Vegetation management with any of the above plant species should be considered as a bioremediation tool for removing boron or selenium from contaminated soils.

Selenium content of foods purchased in North Dakota

Selenium (Se) concentrations in foods are highly variable, and may reflect Se concentration and availability from the soil in which they were grown. In the present study, Se concentrations were determined for a number of foods and dietary ingredients purchased in North Dakota, an area with high soil Se content. Most foods tended to be high in Se, but many, especially corn products, were highly variable. Selenium in beef from North Dakota was much higher than in beef from low Se areas. These results show that average reported values for Se in foodstuffs are unreliable and if an accurate determination of Se intake is needed, Se concentration should be determined for foods consumed.

Selenium Contents in Astragalus and Uncultivated Soils in Japan.

This reports a study of the selenium (Se) content in some Astragalus (Se indicator plants), related plants (vetch), and soils in Japan. The Se content of Japanese Astragalus was 0.06-2.17 mg/kg of dry weight. The Se content in Hedysarum and Oxytropis, the species of vetch, was 0.05-2.04 mg/kg. We did not find any vetch in Japan in which Se had accumulated. Se content in plants is influenced by Se level in the soil. We measured the Se content in the surface soils in Japan and plotted a Japanese Se map ; the soil content was 0.2-1 mg/kg, except around a few volcanoes such as Tateyama Murodo (148 mg/kg) and Mt. Zao (10.0 mg/kg). We showed in detail the Se content in the soils and plants around the Tateyama Murodo region. The Se content of soils and ashes from many volcanoes such as Mt. Unzen and Mt. Pinatubo (Philippines) was low (0.1-0.6 mg/kg).

Distribution and biomagnification of selenium in a restored upland grassland contaminated by selenium from agricultural drain water

AbstractKesterson Reservoir was a wetland contaminated with selenium (Se)‐enriched agricultural drainage water. As part of the remediation of the selenium contamination, evaporation ponds at Kesterson were dried out and the selenium‐contaminated wetlands were transformed into an upland grassland. The distribution of Se in both the soil and vegetation was monitored in these upland grasslands for 5 years. From May 1989 to September 1993 the distribution of soil Se in the sediment did not change significantly, and the soil Se inventory was not remobilized. Biomagnification of selenium in seven sites representing a gradient of soil Se concentrations was examined for three food‐chain trophic levels. The pattern of Se bioaccumulation shows that there was a considerable increase from the water‐extractable soil Se concentration (source) to the plant (producer) tissue Se concentration and from the grasshopper (primary consumer) tissue Se concentration to praying mantis (secondary consumer) tissue Se concentration. No consistent pattern of increase in Se concentration from the plant to the grasshopper level was apparent. The absolute values of Se bioaccumulation in the insects reflect the available Se concentrations in the soil of the habitat. This relationship indicates that the insects were not actively moving from their local habitat. This discovery suggests that, indeed, a Se biomagnification process did occur in this upland grassland ecosystem. In comparison with the previous state of Kesterson wetland, the upland grassland had Se bioaccumulations less than 10% of those found in the wetland. The upland grassland appears to provide a safer habitat than the wetland with respect to the elevated soil Se concentrations. However, some existing high soil Se concentration sites in the grassland may produce toxic levels of Se in the food chain. Additional research is needed to restore this deteriorated habitat and ensure the safety of wildlife and humans.

Selenium determination by PIXE in healthy and pathological human individuals

Se was measured in plasma and urine samples; the former, a good indicator of daily Se intake, is well correlated with Se content in soils; the latter indicates Se balance and variations. The analysis was performed by PIXE with samples prepared following a specific preconcentration procedure, using 600 (μg of tellurium both as a coprecipitating agent and as an internal standard. Data obtained in 375 individuals (183 healthy subjects and 192 subjects with various physiological and pathological conditions) showed low plasma Se mean values in healthy individuals; further reduction was observed in some pathological conditions.

Natural Establishment and Selenium Accumulation of Herbaceous Plant Species in Soils with Elevated Concentrations of Selenium and Salinity under Irrigation and Tillage Practices

The effects of irrigation and tillage practices were studied on species richness, biomass, and selenium accumulation of naturally established herbaceous plants in soils with elevated levels of selenium (Se) and salinity at Kesterson Reservoir, Merced County, California. The four different irrigation-tillage practice combinations were (1) no irrigation, no tillage; (2) irrigation, no tillage; (3) no irrigation, tillage; and (4) irrigation, tillage. The fields were allowed to become colonized naturally by herbaceous plant species. For the Mediterranean climate in the study site, irrigation was conducted biweekly through the summer months, and tillage was done in 3-month intervals. Biomass and Se accumulation of Atriplex patula L, Bassia hyssopifolia Kuntze, Rev. Gen. P1., Melilotus indica (L.) All., and Solola kali L. were substantially affected by irrigation. The degree and direction of the effects were found to be species dependent. The field plots which were tilled at 3-month intervals remained bare throughout the experiment. The total soil Se concentrations in the top 15 cm soil horizon were found to be in the range of 40 to 70 mg kg−1 dry wt. Soil Se concentrations below 25 cm soil depth were much lower and within a range of 2 to 4mg kg−1. Less than 110th of the total soil Se inventory in the top soil horizon was water extractable, and the distribution of the Se inventory did not change significantly over the period of 1990 and 1991 despite the irrigation and tillage practices suggesting that a large portion of the Se inventory was not remobilized. The water-extractable soil Se concentration was found to be significantly lower in soils with the greatest biomass production suggesting an effective bioextraction of soil selenium by the native herbaceous plants.

Uptake and accumulation of selenium by terrestrial plants growing on a coal fly ash landfill. Part 2. Forage and root crops

Plants grown on fly ash landfills can accumulate relatively high concentrations of selenium (Se), although concentrations can vary greatly among and within species. We examined the accumulation of Se in forage and root crops grown on a fly ash landfill and nonlandfill sites and the relationship of soil Se to plant Se concentrations. Because sulfur (S) can act as a competitive ion with Se in plant uptake of nutrients, gypsum (CaSO4.2H2O) was applied to soil on a fly ash landfill to determine whether Se was reduced in plants in its presence. Slightly more Se was accumulated in plants grown on the landfill than on the nonlandfill site. Total Se concentration in soil was poorly correlated with Se concentration in alfalfa plants grown on the landfill. In alfalfa (Medicago sativa L.), oats (Avena sativa L.), and rutabaga (Brassica napus L.), application of gypsum at rates of 5.6 to 16.8 t ha−1 reduced the uptake of Se from that of plants grown without gypsum. Results from this study indicate that gypsum amendment may be effective in decreasing the uptake of Se by plants growing on a fly ash landfill, but the response is quite variable, probably due to variability in concentration and availability of Se in the soil cap. The use of gypsum in limiting Se uptake by plants offers a possible management tool to control the cycling of Se through plants to other biota on fly ash landfills.

Selenium in Kesterson Reservoir Ephemeral Pools Formed by Groundwater Rise: II. Laboratory Experiments

AbstractThe formation of seleniferous ephemeral pools that result from shallow water table rise through seleniferous soils was studied in laboratory columns of soils from Kesterson Reservoir, Merced County, California. Variables included in the column experiments included the depth interval of the soils, the rate of shallow water table rise and temperature. The columns were packed with either surface (0–0.15 m) soils (with and without the original salt crust), or subsurface soils (0.15–0.30 m) sampled from the southwest corner of Pond 1, Kesterson Reservoir. Controlled inputs of nonseleniferous, saline water through the bottoms of the columns provided water table rise rates of 3, 10 and 30 mm d−1. The soil columns were maintained at either room temperature (≈25°C) or 5°C. The amount of Se transported from the soils into the overlying ponding waters was proportional to the water‐extractable soil Se content, and was positively correlated with the rate of water table rise. The 5°C experiments resulted in greater Se transfers into the ponding waters in the columns subjected to 10 and 30 mm d−1 rates of water table rise (relative to comparable room temperature columns), while the reverse effect was observed with 3 mm d−1 columns.

Selenium deficiency in yugoslavia

Data on selenium (Se) deficiency in Yugoslavia are presented. The results include Se content of soil, cereal crops, and garlic grown in these soils, and human serum and scalp hair from several towns and regions. All data indicate a serious Se deficiency: soil (n = 140), the mean value of 200 +/- 69.6 micrograms/kg Se; wheat, (58) mean = 20.5 +/- 12.4 micrograms/kg; corn, (79) mean = 13.7 +/- 13.6 micrograms/kg; and garlic, (66) mean = 13.7 +/- 17.1 micrograms/kg Se. Analyses of human tissue show a very low Se status of the Yugoslav population: serum, (n = 875) mean = 50.0 +/- 18.0 micrograms/L and scalp hair, (388) mean = 94 +/- 16 micrograms/kg Se. In some regions, Se contents of grain, garlic, and human serum and hair are approaching those in the low-Se belt in China. It is assumed that very low Se status of a human population could be a risk factor in the development of Balkan Endemic Nephropathy (BEN) and in a high incidence of urinary tract tumors (UTT) in endemic areas.

Species richness and selenium accumulation of plants in soils with elevated concentration of selenium and salinity

Field studies were conducted in soils with elevated concentrations of Se and salinity at Kesterson, California. Biomass distribution, species richness, and selenium accumulation of plants were examined for two sites where 15 cm of surface soil was removed and replaced with fill dirt in the fall of 1989, and two sites were native soil cover. The Se concentrations in the top 15 cm of fill dirt ranged from undetectable to 36 ng g −1. For the native soil sites, Se levels ranged from 75 to 550 ng g −1. Soil Se concentrations below 15 cm ranged from 300 to 700 ng g −1 and were comparable between the fill dirt and the native soil sites. At least 20 different plant species were brought into the two fill dirt sites with the top soil. Avena fatua L., Bassia hyssopifolia Kuntze Rev. Gen. Pl., Centaurea solstitialis L., Erysimum oficianale L., Franseria acanthicarpa Cav. Icon., and Melilotus indica (L.) All. contributed over 60% of the total biomass. Only 5 species were found in the native soil sites, and salt grass ( Distichlis spicata L.) was the predominant species and accounted for over 80% of the total biomass. Between 1989 and 1990, two years after the surface soil replacement, the two fill dirt sites had a 70% reduction in species richness. Plant tissue selenium concentrations were found to be quite variable between plant species and between sites of sampling. At the fill dirt sites, the plant species with deep root systems accumulated greater amounts of selenium than the shallow-rooted species. The soil selenium concentration of the field soil had no negative effect on pollen fertility, seed set, and seed germination for the plant species examined. However, seedling growth was impaired by the soil selenium concentrations. This suggests that a selection pressure of soil Se concentration may have been imposed on plant species such as M. indica in an early stage of its life cycle.

Selenium accumulation and selenium tolerance of salt grass from soils with elevated concentrations of Se and salinity

Biomass production, selenium accumulation, and the role of the bioextraction of selenium by salt grass ( Distichlis spicata L.) in soils with elevated concentrations of Se and salinity at Kesterson, California, were studied. Salt grass contributed more than 80% vegetative coverage and 90% dry weight in the grassland communities where the soil Se concentrations were 100 times (1000 to 3000 μg kg −1) higher than the Se concentrations found in soils of the control sites. No evidence for evolution of Se tolerance was found in the salt grass populations. The successful colonization of salt grass in the soil with elevated Se and salinity is attributable to the presence of high concentrations of soil sulfate. Salt grass accumulated less Se than other salt-tolerant plant species existing in the same area, and no predation of animals and insects on salt grass has been noticed. Salt grass can transpire substantial amounts of volatile Se through its plant tissue. Under field conditions, a 1-m 2 salt grass plot may produce 180 μg volatile selenium per day. However, no reduction of soil Se concentration in the salt grass habitat was detected over a period of 1 year. A long-term monitoring of Se status is needed in order to make predictions of the effectiveness of efforts to clean up Se-contaminated soils through the use of native plant species.

Mineral status of sheep in the Paramo region of Colombia. II. Trace minerals

Three sheep classes (pregnant-lactating ewes, lambs and yearlings) were studied to determine the trace mineral status of grazing animals from three sheep farms located in the Paramo region of the Cordillera Oriental in Colombia. At the end of the rainy season (May–June, 1987) and middle to end of the dry season (February, 1988), soil, forage, blood and liver samples were collected. Soil Zn and forage Co, Cu, Mn and Mo concentrations were affected by season ( P < 0.05). Soil Se and Mn concentrations were deficient during both rainy and dry seasons (100% and 54%, respectively). Forage Co and Cu were deficient (87% and 75%, respectively); but Cu was 94% during the dry season. Mo values were below the toxic limit for sheep of 6 ppm, and the Cu:Mo ratio was at least 4:1. Fe and Mn were in excess of requirements for sheep but below maximum tolerable levels. Blood serum analyses showed only small deficiencies, liver for Cu (59%), Zn (44%), and for Co (55%) during the dry season. No differences ( P ≯ 0.05)were found among animal classes for any plasma and liver trace elements in both seasons. Ewes were more deficient in liver Zn (58%) and liver Cu (71%); yearlings in liver Co but lambs were about as deficient in liver Cu (69%) as ewes. Based primarily on liver analyses it was concluded that Cu, Zn and Co were the most deficient trace elements. These plus Se should be continually supplemented in the Paramo of Colombia. There was no direct relationship between soil and plant trace mineral concentrations, however, mineral imbalance problems in livestock could be predicted from forage and animal tissue analyses.

Adding selenium‐enriched plant tissue to soil causes the accumulation of selenium in alfalfa

Abstract Greenhouse experiments were conducted to determine selenium (Se) uptake by alfalfa (Medicago sativa L.) grown in soils amended with Se‐laden mustard plant tissue. The experimental design was a completely randomized block with treatments consisting of 5, 10, 20, and 40 g of added dried Se‐containing mustard tissue to the soil, which resulted in soil Se concentrations of 1.0, 1.6, 3.0, and 5.7 mg Se/kg, respectively. Four clippings of alfalfa were made and the vegetative portions analyzed for dry weight and total Se. Plant dry weight yields and heights of plants were significantly reduced only at the highest Se treatment rate. Mean tissue Se concentrations increased from 1.8 mg Se/kg DM at the 5 g treatment rate to 6.0 mg Se/kg DM at the 40 g treatment rate. Based on this study, alfalfa can accumulate Se during establishment year when Se‐laden mustard plant tissue is added to the soil.

Selenium tolerance, salt tolerance, and selenium accumulation in tall fescue lines

High levels of soil salinity and Se concentration are coexisting problems in the San Joaquin Valley, California. Tall fescue is a potentially useful crop plant for land management in soils containing elevated concentrations of Se and salinity. Information regarding its physiological mechanism and genetic variation of Se accumulation in this species is scant. Thirteen tall fescue ( Festuca arundinacea Schreb.) lines were examined for Se and salt tolerances and Se accumulation in nutrient solution culture. Genetic variation of both Se and salt tolerances was detected among six American cultivars and seven worldwide tall fescue lines. Selenium tolerance and salt tolerance are independent of each other and are negatively correlated with tissue Se and salt concentrations. These relationships suggest that an exclusion mechanism is responsible for the tolerance. This diversity of Se and salt tolerance and Se accumulation among the tall fescue lines is important for the application of this species for land management.

Selenium toxicity in soils, plants and animals in some parts of Punjab, India

Pockets of seleniferous soils have been identified in north eastern parts of Punjab, India, by examining the Se content of soils, irrigation water, plants and animal tissues. Toxic sites ranging from 4 ‐ 16 ha were sporadically distributed in the study area and occupied more than 100 ha. In the seleniferous areas, the selenium content of surface (2.12 ± 1.13 mg kg‐1) and sub surface (1.16±0.51mg kg‐1) layers of soils was 4–5 times higher than that of nonseleniferous areas. It seems that the deposition of seleniferous materials transported by seasonal rivulets from higher reaches of the Siwalik hills and use of underground water for frequently irrigating crops like lowland rice lead to the development of seleniferous pockets in the study area.

Chloride and Sulfate Salinity Effects on Selenium Accumulation by Tall Fescue

The discovery of high levels of Se in soil and water samples from the San Joaquin Valley, California, and of its responsibility for deformity and death of wildlife at Kesterson National Wildlife Refuge have renewed interest in the bioaccumulation of this element. Greenhouse nutrient solution culture and field experiments were conducted to examine the effects of Cl and SO4 salt on growth and Se accumulation in tall fescue (Festuca arundinacea Schreb.) cultivars Alta, Falcon, and Olympic. Sulfate salt substantially reduced growth inhibition and Se accumulation. Tall fescue from the field irrigated with water low in salinity had higher tissue Se concentration than plants from the field irrigated with water high in salinity. No difference in tissue Se concentration was found among the three tall fescue cultivars; however, forage‐type Alta produced the most shoot biomass and accumulated the most total Se. The soil irrigated with water high in salinity had 10 times higher Se concentration thansoil irrigated with water low in salinity. The highest soil Se concentration was found in the top 15 cm of soil. Growing fescue for one year reduced soil Se by 50%. Selenium concentrations below 15‐cm depth were lower and similar between the bare soil and the soil under tall fescue. Both the high and low salinity water irrigations did not cause high levels of Se accumulation by the tall fescue cultivars unless there was continual addition of Se into the system. This study generated important information for Se bioaccumulation management in soils with elevated salinity and Se levels.

Selenium content and distribution in various Japanese soils

Abstract The Se contents of Japanese mountain soil profiles, surface soils of grasslanc and paddy lands were measured. The average total Se content of grassland soils was 0.89 ppm (N=25), about two times as high as that of surface mountain (0.57 ppm, N=6) and paddy soils (0.46 ppm, N=44). The Se distribution patterns of six mountain soil profiles were investigated. The soils derived from a homogeneous parent material showed a high Se content in the surface organic horizon. However in the soils which had undergone some changes in their profiles such as the addition of other materials, the Se distribution pattern was affected by the Se content and the extent of influence of the additional material. The water-soluble Se contents of grassland and paddy soils were 14.2 and 14.4 ppb, respectively, corresponding to 2.30 and 3.85% of the respective total Se content. The total Se contents of various Japanese soils were comparable to, or even slightly higher, than those reported from other countries. However, the w...

Effects of Soil Flooding on Selenium Transformations and Accumulation by Rice

AbstractThe fate of Se in flooded soil is not well known. This greenhouse study was conducted to determine the fate of Se in flooded soil and to determine the effects of Se on plant growth. Rice plants (Oryza sativa L. cv. M101) were grown in pots containing Panoche loam soil (fine‐loamy, mixed, calcareous, thermic Typic Torriorthents) to which 0, 1.5, 3, and 6 mg Se kg−1 as Na2SeO4 was added. Rice was grown in continuously flooded or nonflooded (upland) soil. The flooded treatments were amended with organic matter (OM) at concentrations of 0, 2.5, and 5 g cellulose kg−1. Soil solution samples were taken weekly from the flooded treatments and analyzed for pH, Eh, EC, and Se concentration and Se oxidation state. Plants were harvested and analyzed for Se at three plant growth stages. Selenate soil solution concentrations were reduced 95% after 6 and 10 wk following flooding for the 5.0 and 0 g OM kg−1 treatments, respectively. Selenite in solution reached a maximum concentration (340‐1920 µg Se[IV] L−1) 5 to 8 wk after flooding and then decreased to trace levels (&lt;0.5 µg L−1). Selenium accumulated in all rice plant parts in direct proportion to the added Se. Plants grown in flooded soil with added OM had tissue Se concentrations &lt;20% that of rice grown without added OM or in upland conditions. Selenium phytotoxicity symptoms were observed in plants grown in flooded soil without OM and in the upland soil when Se was added. Tissue Se concentrations associated with a 10% reduction in shoot dry matter were 160 and 81 mg Se kg−1 for upland and flooded rice (without added OM). No Se‐induced yield loss occurred when OM was added to flooded soil. Flooding those soils containing Se[VI] may be an effective way to reduce soluble Se concentrations in soil to nontoxic concentrations.

Selenium in soils and plants of the Jordan Valley

The selenium (Se) content of plants and soils in the northern part of the Jordan Valley, a semi-arid region, was determined by a fluorometric method. Leguminosae, Gramineae, and Cruciferae were found to contain the highest amounts of Se. Of the Leguminosae, Alhagi maurorum contained 4·70 μg Se/g and Prosopis farcta from the north end of the Dead Sea and North Shunah contained 0·55 and 600 μg Se/g, respectively. Of the Gramineae, Cynodon dactylon, Hordcum spontaneum , Setaria verticillata, and Sorghum halepense contained 0·08 to 4·0, 5·26, 10·48 and 3·44 μg Se/g, respectively. Sinapsis alba (Cruciferae) contained 12·67 μg Se/g. Other families found to have less than 1 μg Se/g are represented by Chenopodium murale (Chenopodiaceae) and Silene conoidea (Caryophyllaceae). The Se content of C. dactylon was positively correlated with total Se in the soil. The water-soluble Se in the soils was 0·0025 μg/g (pH 8·01–8·12) around the Dead Sea and 0·107 μg/g (pH 7·60–7·80) in North Shunah. The corresponding average total Se was 1·115 and 4·043 μg/g in these two locations, respectively.

Selenium deficiency in total parenteral nutrition

A clinical selenium (Se) responsive syndrome was observed in a patient on total parenteral nutrition (TPN). The Se concentrations in plasma, erythrocytes and whole blood and the activity of glutathione peroxidase, (GSHPx (EC 1.11.1.9)) were measured at intervals in 22 patients receiving TPN for 10 to 40 days. Plasma Se reached very low levels and included the lowest value observed in adult man (<10 ng Se/ml), similar to those in animals with Se-responsive diseases in New Zealand. Metabolic balance studies were carried out for 7 to 12 days on six of these patients during TPN. Se intake was negligible and despite the relative decrease in urinary losses (7.6 µg Se/day) and gastrointestinal and other losses, there was a marked negative balance (−10 µg Se/day). Other factors predisposing to a low Se status in these patients included living in a region with a low soil Se content and the effect of surgical stress. One patient with plasma Se of 9 ng Se/ml developed muscle pain and tenderness in the thighs with a resulting inability to walk which responded within a week to Se supplementation alone. Most of Se supplement was retained but this had produced at the end of 24 days of supplementation only an initial minor increase in plasma Se and little change in erythrocyte Se and GSHPx activity. For the patients on TPN plasma Se and 24-hr urinary Se excretion were closely related, much as reported previously for healthy New Zealand subjects and for Swedish patients on TPN. The close association between erythrocyte Se and GSHPx activity with TPN and blood transfusion could indicate that for these patients erythrocyte Se was largely determined by Se from GSHPx. This study adds further evidence for the essentiality of Se in man and demonstrates the need to consider Se supplementation in longterm TPN.