Contamination by arsenic and other trace elements in tube-well water and its risk assessment to humans in Hanoi, Vietnam

Concentrations of As and other trace elements and their association were examined in groundwater (n = 25) and human hair (n = 59) collected at Gia Lam District and Thanh Tri District, suburban areas of Hanoi, Vietnam, in September 2001. Concentrations of As in the groundwater ranged from <0.10 to 330 microg/l, with about 40% of these exceeding WHO drinking water guideline of 10 microg/l. Also, 76% and 12% of groundwater samples had higher concentrations of Mn and Ba than WHO drinking water guidelines, respectively. Arsenic concentrations in hair of residents in Gia Lam and Thanh Tri Districts (range 0.088-2.77 microg/g dry wt.) were lower than those in other As-contaminated areas of the world, but were higher than those of people in non-contaminated areas. Concentrations of As and Mn in hair of some individuals from the Gia Lam and Thanh Tri Districts exceeded the level associated with their toxicity and, therefore, a potential health risk of As and Mn is a concern for the people consuming the contaminated water in this area. Cumulative As exposure was estimated to be lower than the threshold levels at the present, which might explain the absence of manifestations of chronic As poisoning and arsenicosis in the residents of Gia Lam and Thanh Tri Districts. To our knowledge, this study revealed for the first time that the residents are exposed not only to As but also Mn and Ba from groundwater in the Red River Delta, Vietnam.     

Maternal-fetal distribution and transfer of dioxins in pregnant women in Japan, and attempts to reduce maternal transfer with Chlorella (Chlorella pyrenoidosa) supplements

Dioxins can be transferred from mother to fetus via the placenta, or to nursing infants via breast milk, potentially causing developmental health problems in children. To assess pediatric health risks from dioxins, exposure of mothers and children to dioxins must be clarified. Methods of reducing maternal transfer of dioxins should also be investigated. Concentrations of 28 dioxin (polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and co-planar polychlorinated biphenyls) congeners in blood, adipose tissue, breast milk, cord blood and placenta collected from 44 pregnant Japanese women were measured. In addition, to investigate potential reductions in maternal transfer of dioxins, 23 pregnant women were instructed to take Chlorella pyrenoidosa supplements during pregnancy. Correlations were observed between dioxin total toxic equivalents (total TEQ) in blood and total TEQ in adipose tissue (r=0.913, P<0.0001), breast milk (r=0.695, P=0.0007), and cord blood (r=0.759, P<0.0001). Dioxin levels transferred to fetuses and nursing infants reflect cumulative maternal concentrations of dioxins. A linear regression equation was introduced to predict total TEQ in breast milk and cord blood from dioxin levels in maternal blood, which should prove useful in evaluating fetal and infant risk of dioxin exposure. Total TEQ in cord blood were approximately 26% lower than in maternal blood (P<0.0001). The results of this study suggest that transplacental transfer differs depending on the dioxin congener. Total TEQ in breast milk were approximately 30% lower in the Chlorella group than in controls (P=0.0113). This finding suggests that maternal transfer of dioxins can be reduced using dietary measures such as Chlorella supplements.     

Species composition and soil erosion on a ski area in Hokkaido,northern Japan

In 1986 and 1987, a study on factors governing revegetation on ski grounds was conducted at Teine ski ground (built in 1971) located near the city of Sapporo in northern Japan. Soil movement, slope gradient, distance from forest edge, vegetation cover, and number of species on the ski ground were examined. Although artificial sowing of exotic plants was undertaken in the whole ground surface at the time of opening, bare land occurred in ca. 50% of surveyed plots and the ski ground was mostly covered with native plants. The number of species was positively correlated to vegetation cover, which was low in the sites where intensive soil erosions occurred in winter. A principal component analysis of plant species distinguished three major groups of factors, i.e., vegetation cover (first axis, contribution rate 30.3%), soil erosion in winter and slope gradient (second, 23.1%), and distance from forest edge (third, 16.3%). The vegetation characteristics on the ski ground were not determined by a single environmental gradient but by the combination of factors described above. In particular, soil movements, which are mostly derived from snowmelt, are considered to be the initiator of vegetation changes.     

TURBULENCE MEASUREMENT OF A FLOW WITH SUSPENDED SOLID PARTICLES1

ABSTRACT: Success in measuring turbulence in water has been achieved by replacing the hot-wire probe by the hot-film probe. Accordingly, these results have greatly increased knowledge and understanding of hydromechanics. However, there are few published measurements of turbulent properties of flow with suspended solid particles. With this in mind, the authors conducted measurements of turbulent properties of flow with suspended solid particles by using a quartz-coated, wedge-shaped hot-film probe. Turbulent intensities and macroscale of eddy change in the flow with suspended solid particles on a movable bed is discussed.     

A study on the Spatial Distribution of Nitrogen and Phosphorus Balance, and Regional Nitrogen Flow Through Crop Production

The spatial distribution patterns of the nitrogen and phosphorus input/intake amounts in crop production within two small basins are examined, based upon a cropping unit distribution map that is obtained from remote sensing data analysis. Firstly, we examine the availability and suitability of approaches to the spatial distribution analysis of cultivation patterns classified from material flow characteristics of crop production using seasonal remote-sensing data. Secondly, material flow units in crop production are grouped according to the cultivation patterns obtained from the remote-sensing data analysis. Consequently, the spatial patterns of the amounts of both nitrogen and phosphorus inputs/intakes through crop production on farmland are examined and their spatial distribution maps are prepared according to the material flow units. In addition, we developed a nitrogen flow and runoff model and the model is simulated based on the examination of the results of spatial distribution patterns of the material flow units. The annual nitrogen runoff from small catchments, where various crops are cultivated, varies from 2.7 kg ha^–1 year^–1 to 108 kg ha^–1 year^–1 and the annual balanced losses of nitrogen in small catchments varied from –30 kg ha^–1 year^–1 to 101 kg ha^–1 year^–1. Also, the monthly changes in soil nitrogen of each material flow unit is estimated at –55 kg ha^–1 as a maximum decrease and 114 kg ha^–1 as a maximum increase. These results indicate that the spatial distribution patterns of nutrient input and intake through agricultural activities should be considered when analyzing the material flows and nutritient movement in soil–water systems in rural areas for watershed environmental control and regional agricultural management.     

Effect of acute nitrogen dioxide exposure on the composition of fatty acid associated with phospholipids in alveolar lavage

In vivo exposure of rats to 10 ppm nitrogen dioxide (NO₂) for 12h caused changes in fatty acids composition of alveolar lavage phospholipids. Among the fatty acid species, the relative ratio of palmitic acid, myristic acid and palmitoleic acid increased significantly. While the relative ratio of stearic acid, oleic acid, linoleic acid and arachidonic acid decreased significantly. Both the increase in the incorporation of palmitic acid in phosphatidylcholine which would be released into the alveoli and the increase in the release of phosphatidylcholine into the alveoli may account for the changes in the fatty acid composition of the present findings.     

Characteristic of organic aerosol in a remote area of Okinawa Island

A continuous investigation of aerosol pollutants in Cape Hedo, Japan was conducted from October 2005 to August 2006 by Aerodyne aerosol mass spectrometer (AMS). This article focused on the analysis of long-range transport of organic aerosol from continental origin to the remote island. Based on the transport distance and air mass origin, four main air mass origins were considered, including North China, South China, Japan and Korea. Although the mass concentration and air mass origin were quite different during study period, the mass spectrum and size distribution of organic matter and oxidized organics were similar, which showed uni-modal distribution with modal diameter of around 500 nm. The loss rate of organics was (5.15 ± 0.55) × 10-⁶ s-¹ obtained by plotting the concentration against the transport time. Conversion rate of SO₂ to sulfate and oxidation rate of organics were (1.07 ± 0.15) × 10-⁵ and (1.09 ± 0.52) × 10-⁶s-¹, respectively.     

Land-Cover Changes and Its Impacts on Ecological Variables in the Headwaters Area of the Yangtze River, China

Land cover changes affect ecological landscape spatial pattern, and evolving landscape patterns inevitably cause an evolution in ecosystem functionality. Various ecological landscape variables, such as biological productivity (plant biomass and stock capacity), soil nutrients (organic matter and N content) and water source conservation capacity are identified as landscape function characteristics. A quantitative method and digital model for analyzing evolving landscape functionality in the headwaters areas of the Yangtze River, China were devised. In the period 1986–2000, patch transitions of the region's evolving landscapes have been predominantly characterized by alpine cold swamp meadow, with the highest coverage tending to be steppified meadow or steppe, and desertification landscape such as sand and bare rock land expansion. As the result of such changes, alpine swamp areas decreased by 3.08 × 10³ km² and the alpine cold sparse steppe and bare rock and soil land increased by 6.48 × 10³ km² and 5.82 × 10³ km², respectively. Consequently, the grass biomass production decreased by 2627.15 Gg, of which alpine cold swamp meadows accounted for 55.9% of this loss. The overall stock capacity of the headwaters area of the Yangtze River decreased by 920.64 thousand sheep units, of which 502.02 thousand sheep units decreased in ACS (Alpine cold swamp) meadow transition. Soil organic matter and N contents decreased significantly in most alpine cold meadow and swamp meadow landscape patches. From 1986 to 2000 the total losses of soil organic matter and total N in the entire headwaters region amounted to 150.2 Gkg and 7.67 Gkg. Meanwhile, the landscape soil water capacity declined by 935.9 Mm³, of which 83.9% occurred in the ACS meadow transition. In the headwater area of the Yangtze River, the complex transition of landscape resulted in sharp eco-environmental deterioration. The main indication for these changes involved the intensity of the climate in this region is becoming drier and warmer, resulting in a gradual degradation of the permafrost.     

Specific accumulation of arsenic compounds in green turtles (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) from Ishigaki Island, Japan

Concentrations of total arsenic (As) and individual compounds were determined in green and hawksbill turtles from Ishigaki Island, Japan. In both species, total As concentrations were highest in muscle among the tissues. Arsenobetaine was a major compound in most tissues of both turtles. High concentrations of trimethylarsine oxide were detected in hawksbill turtles. A significant negative correlation between standard carapace length (SCL), an indicator of age, and total As levels in green turtles was found. In contrast, the levels increased with SCL of hawksbill turtles. Shifts in feeding habitats with growth may account for such a growth-dependent accumulation of As. Although concentrations of As in marine sponges, the major food of hawksbill turtles are not high compared to those in algae eaten by green turtles, As concentrations in hawksbill turtles were higher than those in green turtles, indicating that hawksbill turtles may have a specific accumulation mechanism for As.     

Some mineral constituents of Parasol Mushroom (Macrolepiota procera)

This article reports background concentrations of Ag, Ba, Cd, Co, Cr, Cs, Cu, Ga, Hg, Mn, Mo, Pb, Rb, Sb, Sr, Se, Tl, V and Zn in caps and stalks of M. procera collected from four spatially distant sites across Poland. The elements were determined using inductively coupled plasma-mass spectrometry (ICP-MS), hydride generation atomic absorption spectrometry (HG-AAS) or a cold vapor atomic absorption spectrometry (CV-AAS). Copper, zinc, rubidium, selenium, chromium and cobalt were the most abundant amongst elements determined in this mushroom. Some elements (Cu, Zn, Rb, Se, Pb, Hg, Cd, Mo) occurred at greater concentrations in the caps than stalks of M. procera and some (Ag, Ba, Sr, V, Tl) dominated in the stalks, while for some other this proportion was similar or varied (Mn, Cr, Co, Ga, Sb, Cs) depending on the sampling site. For elements such as copper, zinc, rubidium as well as selenium some spatial similarity in distribution and/or concentration values both in caps and stalks was noted. Cadmium and lead content in caps of M. procera was usually below the European Union tolerance limit value of 2.0 and 3.0 microg/g dw set for cultivated mushrooms, respectively. These two toxic metals have been found in elevated concentration in M. procera from unpolluted stands outside of Poland as reported by some authors, which implies the possibility of relatively high background levels in this species.