Atmospheric mercury concentrations above mercury contaminated mill tailings in the Carson River Drainage Basin,NV

During processing of the historic Comstock Ore, Virginia City, NV, an estimated 5.5 × 10⁹ g of metallic mercury (Hg) were released into the Carson River Drainage Basin. The Bessels Mill site is one of at least 75 locations where Hg was used to amalgamate the gold and silver from the ore. Although the mill is no longer standing, Hg contaminated tailings attest to its past location. Mercury concentrations in samples of tailings from the Bessels Mill site are as high as 1570 μg/g. Mercury concentrations vary spatially over the site. Total Hg concentrations in air measured directly over the site are well above regional background levels (1 to 7.1 ng/m³). The highest average atmospheric Hg concentration measured at the site was 240 ng/m³ for October 1993. The estimated range of Hg flux to the atmosphere from the site was 37 to 500 ng/m² hr. Atmospheric Hg concentrations varied seasonally, diurnally and spatially. Atmospheric Hg concentrations varied as a function of Hg concentration, soil and air temperature, wind speed and surface morphology.     

The toxicity of sublethal lead concentrations for the woodlouse, Porcellio laevis (Crustacea, Isopoda)

 The effects of sublethal concentrations of lead nitrate on the terrestrial isopod Porcellio laevis were studied experimentally under controlled conditions over a period of 8 weeks. Changes in body mass were recorded. Avoidance-behaviour studies were undertaken to determine whether P. laevis can detect and possibly avoid lead in the environment. P. laevis was affected negatively by the presence of lead nitrate and showed a loss in body mass. More than 86% of the total body burden of lead was compartmentalized in the hepatopancreas. The isopods were capable of avoiding leaves contaminated with 200 mg kg^–1 lead nitrate in behavioural tests but did not avoid leaves contaminated with a higher concentration. Received: 10 March 1998     

Effects of various cooking processes on the concentrations of arsenic, cadmium, mercury, and lead in foods

The effects of cooking processes commonly used by the population of Catalonia (Spain) on total arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations in various foodstuffs were investigated. All food samples were randomly acquired in local markets, big supermarkets, and grocery stores of Reus (Catalonia). Foods included fish (sardine, hake, and tuna), meat (veal steak, loin of pork, breast and thigh of chicken, and steak and rib of lamb), string bean, potato, rice, and olive oil. For each food item, two composite samples were prepared for metal analyses, whose levels in raw and cooked (fried, grilled, roasted, and boiled) samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The highest concentrations of As, Hg, and Pb (raw and cooked samples) were mainly found in fish, with a clear tendency, in general, to increase metal concentrations after cooking. However, in these samples, Cd levels were very close to their detection limit. In turn, the concentrations of metals in raw and cooked meat samples were detected in all samples (As) or only in a very few samples (Cd, Hg, and Pb). A similar finding corresponded to string beans, rice, and olive oil, while in potatoes, Hg could not be detected and Pb only was detected in the raw samples. In summary, the results of the present study show that, in general terms, the cooking process is only of a very limited value as a means of reducing metal concentrations. This hypothetical reduction depends upon cooking conditions (time, temperature, and medium of cooking).     

Hematological and physiological responses to sublethal concentrations of cadmium in a freshwater teleost,Tilapia zillii

Blood from Tilapia zillii exposed to three sublethal concentrations of Cd (10.62, 17.70 and 24.78 mg L^?1) for 24, 48, 72 and 96 hr was analyzed to identify and evaluate changes in erythrocyte count (RBC), hematocrit (Ht), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), erythrocyte sedimentation rate (ESR), leucocyte count (WBC), differential leucocyte counts, total protein, glucose and lactic acid. Hematological and physiological changes attributable to Cd poisoning were observed. Fish showed obvious signs of stress at 17.70 and 24.78 mg L^?1 Cd. Clear time related effects of Cd on the biochemical factors were recorded. The severe stress conditions caused by Cd may be responsible for the hematological and physiological changes in blood.     

Wet deposition of mercury and ambient mercury concentrations at a site in the Lake Champlain basin

The “Great Waters” program, established in the 1990 Clean Air Act Amendments, mandated that atmospheric deposition of hazardous air pollutants to Lake Champlain (including Hg) be assessed. An assessment of the magnitude and seasonal variation of atmospheric Hg deposition in the Lake Champlain basin was initiated in December 1992 with one year of event precipitation collection, as well as collection of vapor and particle phase Hg in ambient air. Samples were collected at the Vermont Monitoring Cooperative air monitoring site at the Proctor Maple Research Center in Underhill Center, VT. The average volume-weighted concentration for Hg in precipitation was 8.3 ng/L for the sampling year and the average amount of Hg deposited with each precipitation event was 0.069 μg/m². The total amount of Hg deposited through precipitation during 1993 was 9.26 μg/m²/yr. A seasonal pattern for Hg in precipitation was evident, with increased concentrations and deposition during spring and summer months. Meteorological analysis indicated the highest levels of Hg in precipitation were associated with regional transport from the south regardless of season, and with transport from the west, southwest and northwest during spring and summer months. Concentrations of ambient vapor phase Hg were typical of rural locations and consistent across seasons. Ambient particulate Hg concentrations averaged 11 pg/m³ with highest concentrations during the winter months.     

汞沉淀对黑麦草中汞含量及其分布的影响

A grass(Italian rye grass)experiment with complete desing of three factos(Hg,grass and exposure)and two levels(with and withou the factor tested)was carried out in Goeteborg,Sweden from May to September,1995,toward understanding the effect of mercury deposition on plant Hg content and its distribution.It has been found that besides the two general pathways of Hg absorption,i.e.root uptake and foliar absorption,mercury deposition can aslo signifcantly incease Hg content and total load in grass.Such effects seem to be confined only within the above-ground parts of grass plant.Estimate has been made to make clear of the contributions of different pathways to Hg Content and total Hg load in the upper part of grass.Results showed that the contribution of Hg deposition accounted for 27%-32%,of Hg content in the above-ground parts of grass plant without adding Hg to the soil.decreasing with the increase of soil and/or air Hg concentrations.The increment of Hg load in the upper part of grass plant caused by Hg deposition during an interval of two weeks varied between 0.01-0.07μg pt^-1,contributing to 17%-48% of the total Hg load in grass plant exposed.     

Effect of biobed composition, moisture, and temperature on the degradation of pesticides

Biobeds retain and degrade pesticides through the presence of a biobed mixture consisting of straw, peat, and soil. The effects of biobed composition, moisture content, and temperature on pesticide degradation were investigated in laboratory studies. Straw produced the main microbial activity in the biobed mixtures as strong positive correlations were observed between straw, respiration, and phenoloxidase content. Most pesticides investigated were dissipated by cometabolic processes, and their dissipation was correlated with respiration and/ or phenoloxidase content. More pesticides were more dissipated at biobed moisture levels of 60% water holding capacity (WHC) than at 30% and 90% WHC, while 20 degrees C gave higher dissipation rates than 2 and 10 degrees C. A straw:peat:soil ratio of 50:25:25% v/v is recommended in field biobeds since this produces high microbial activity and low pH, favorable for lignin-degrading fungi and phenoloxidase activity.     

Effect of brown seaweed lipids on fatty acid composition and lipid hydroperoxide levels of mouse liver

Brown seaweed lipids from Undaria pinnatifida (Wakame), Sargassum horneri (Akamoku), and Cystoseira hakodatensis (Uganomoku) contained several bioactive compounds, namely, fucoxanthin, polyphenols, and omega-3 polyunsaturated fatty acids (PUFA). Fucoxanthin and polyphenol contents of Akamoku and Uganomoku lipids were higher than those of Wakame lipids, while Wakame lipids showed higher total omega-3 PUFA content than Akamoku and Uganomoku lipids. The levels of docosahexaenoic acid (DHA) and arachidonic acid (AA) in liver lipids of KK-A(y) mouse significantly increased by Akamoku and Uganomoku lipid feeding as compared with the control, but not by Wakame lipid feeding. Fucoxanthin has been reported to accelerate the bioconversion of omega-3 PUFA and omega-6 PUFA to DHA and AA, respectively. The higher hepatic DHA and AA level of mice fed Akamoku and Uganomoku lipids would be attributed to the higher content of fucoxanthin of Akamoku and Uganomoku lipids. The lipid hydroperoxide levels of the liver of mice fed brown seaweed lipids were significantly lower than those of control mice, even though total PUFA content was higher in the liver of mice fed brown seaweed lipids. This would be, at least in part, due to the antioxidant activity of fucoxanthin metabolites in the liver.     

湿沉淀对采汞地区山地土壤中汞的影响

There is abundance of Mercury mine resurces in the Fanjinshan Mountain,Mining mercury has a long history there,The concentration of geseous Hg produced in smelting He reaches 20-50mg/m^3 in the tail gas.Because mercury element is an easily transferring microelement,the paper talks about the effect of mercury in Hg mining in Guizhou Province on alpine soil,analyses Hg content in alpine soil at 2000 m of relative elevation in the Hg mining area,and explores for causes of the Hg pollution.     

Effect of lime,P, and Mg on growth and elemental concentrations of mugwort

Abstract

There is evidence that mugwort (Artemisia vulgaris L.) may have potential for use as a livestock forage. This study was undertaken to determine mugwort growth response to lime, P, and Mg, and their effect on elemental concentration of plant material.

Factorial combinations of 0, 5.6, and 11.2 mt lime/ha; 0, 112, and 224 kg P/ha; and 0, 224, and 448 kg Mg/ha were applied to low pH soil in greenhouse pots and planted to mugwort. In the absence of lime and Mg, growth was very poor. Lime was the most effective treatment in promoting mugwort growth. Growth response to Mg was greatest in the absence of lime, and response to P was dependent on lime and/or Mg application. Macronutrient concentrations of mugwort plants were considered adequate for use as forage for non‐lactating beef cows. Concentrations of several of the micronutrients were very high, especially at low lime and Mg. Copper was high at all treatments.     

Total concentrations of mercury in Wisconsin (USA) lakes and rivers

We analyzed surface waters from 30 Wisconsin lakes and rivers for total mercury ([Hg]_T) and total suspended particulates (TSP) on a state-wide basis with trace-metal ‘ultraclean’ techniques. Mercury concentrations ranged from 0.3 to 2.9 ng L^?1 in lakes and from 0.7 to 8.9 ng L^?1 in rivers. TSP concentrations ranged from 0.9 to 6.6 mg L^?1 in lakes and from 3.1 to 31.4 mg L^?1 in rivers. Spatial trends were weak; however, [Hg] _T was generally higher in the spring than in the autumn of 1991. Total mercury concentration was weakly dependent on TSP with the coefficient of determination (r ²) ranging 0.06 to 0.49 across seasonal and geophysical differences.     

Effects of vegetation type on mercury concentrations and pools in two adjacent coniferous and deciduous forests

Vegetation type and ecosystem structure affect major aspects of the mercury (Hg) cycle in terrestrial ecosystems which serve as important storage pools for a long‐term legacy of natural and anthropogenic Hg release to the environment. The goal of this study was to evaluate the integrated effects of 80 y of different vegetative type on Hg accumulation and partitioning in terrestrial ecosystems by comparing Hg concentrations and pools of two adjacent forests: a coniferous Douglas fir (Pseudotsuga menziesii) and a deciduous red alder (Alnus rubra) stand. These stands grew for > 80 y in close proximity (200 m) with identical site histories, soil parent materials, and atmospheric exposure. Results showed that the Douglas fir stand was characterized by significantly higher Hg concentrations and Hg : C ratios in aboveground biomass compared to the deciduous red alder forest. For foliage, higher Hg concentrations (plus 43 μg kg^–1) were expected due to foliage age, but Hg concentrations also were higher in woody tissues (by 2 to 18 μg kg^–1) indicating increased uptake of atmospheric Hg by coniferous tissues. These differences were reflected—and further increased—in litter horizons where Hg‐concentration differences increased in highly decomposed litter to > 200 μg kg^–1. In soils, no difference in concentrations of Hg was observed, but Hg : C ratios were consistently higher in the coniferous Douglas fir. Estimation of pool sizes of C and Hg in soils and at the whole ecosystem level showed that considerably smaller C pools in the coniferous stand as a result of faster C turnover and lower productivity did not lead to corresponding declines in Hg‐pool sizes. The partitioning of Hg among ecosystem components—including distribution between aboveground and belowground components and distribution through the soil profile—was largely unaffected by forest type. Methyl‐Hg concentrations observed in litter layers were also significantly higher in litter of Douglas fir, along with a higher proportion of methylated Hg of total Hg. In soils, methyl‐Hg concentrations were similar in both stands. Comparison of these adjacent forest stands highlights that vegetation type affects concentrations of total Hg in otherwise equivalent sites and that differences also exist in respect to methylated Hg.     

Effect of salinity on stomatal resistance,proline, and mineral composition of pepper

Pepper (Capsicum annuum L.) plants grown in pots were irrigated with the nutrient solutions containing 50, 75, and 100 mM NaCl or a control solution. Salinity markedly decreased plant growth. Increasing salinity levels increased stomatal resistance and sodium (Na), chloride (Cl), proline contents of the plants. Potassium (K), total‐nitrogen (N), and chlorophyll content of the plants were decreased under high salinity conditions.     

Effect of corn cultivar,phosphorus and potassium on yield and chemical composition

A corn cultivar × P × K factorial experiment was conducted to evaluate differential responses of selected parameters to P and K soil fertility. Yield along with leaf nutrient concentration of some nutrients differed among cultivars and nutrient concentration of some elements was affected by soil fertility. Leaf K and Mg were more consistently affected by K fertility than other variables studied. Fertility effects upon micronutrient leaf concentration were not consistent among cultivars or between years.     

Effect of variety, processing, and storage on the flavonoid glycoside content and composition of lettuce and endive

Eight varieties of lettuce (Lactuca sativum) and three varieties of endive (Cichorium endivia) were analyzed for flavonoid composition and content. Total flavonoid contents, expressed as units of aglycon for fresh material, were in the ranges of 0.3-229 microg/g for lettuce and 44-248 microg/g for endive. Five quercetin conjugates [quercetin 3-O-galactoside, quercetin 3-O-glucoside, quercetin 3-O-glucuronide, quercetin 3-O-(6-O-malonyl)glucoside, and quercetin 3-O-rhamnoside] and luteolin 7-O-glucuronide were measured in the green-leafed lettuce and an additional two cyanidin conjugates [cyanidin 3-O-glucoside and cyanidin 3-O-[(6-O-malonyl)glucoside]] in the red-leafed varieties. Three kaempferol conjugates [kaempferol 3-O-glucoside, kaempferol 3-O-glucuronide, and kaempferol 3-O-[6-O-malonyl)glucoside]] were measured in each of the endive varieties. The presence and identity of kaempferol 3-O-(6-O-malonyl)glucoside in endive was shown for the first time. Shredding of lettuce leaf followed by exposure to light produced significant losses of the flavonoid moiety in the green oak leaf (94%), red oak leaf (43%), iceberg (36%), green batavia (25%), lollo biondo (24%), and lollo rosso (6%) samples, whereas cos and green salad bowl samples did not show an overall loss. Shredding of endive also produced loss of the flavonoid moiety in escarole (32%), fine frisee (13%), and coarse frisee (8%). Significant demalonation was observed for both the quercetin and cyanidin glucosides in lettuce, whereas a similar degradation of the kaempferol analogue was found in endive tissue. Storage of whole heads of both lettuce and endive in the dark at 1 degrees C and 98% humidity for 7 days resulted in losses of total flavonol glycosides in the range of 7-46%. The identification of the amounts, position of substitution, and nature of the sugars is important for understanding the potential bioavailability and biological activities of flavonoids in salads.     

Effects of throughfall and litterfall manipulation on concentrations of methylmercury and mercury in forest‐floor percolates

The forest floor was shown to be an effective sink of atmospherically deposited methylmercury (MeHg) but less for total mercury (Hg_total). We studied factors controlling the difference in dynamics of MeHg and Hg_total in the forest floor by doubling the throughfall input and manipulating aboveground litter inputs (litter removal and doubling litter addition) in the snow‐free period in a Norway spruce forest in NE Bavaria, Germany, for 14 weeks. The MeHg concentrations in the forest‐floor percolates were not affected by any of the manipulation and ranged between 0.03 (Oa horizon) and 0.11 (Oi horizon) ng Hg L^–1. The Hg_total concentrations were largest in the Oa horizon (24 ng Hg L^–1) and increased under double litterfall (statistically significant in the Oi horizon). Similarly, concentrations of dissolved organic C (DOC) increased after doubling of litterfall. The concentrations of Hg_total and DOC correlated significantly in forest‐floor percolates from all plots. However, we did not find any effect of DOC on MeHg concentrations. The difference in the coupling of Hg_total and MeHg to DOC might be one reason for the differences in the mobility of Hg species in forest floors with a lower mobility of MeHg not controlled by DOC.     

土壤中亚致死剂量毒死蜱对蚯蚓抗氧化防御系统酶活性的影响

以赤子爱胜蚓(Eisenia fetida)为供试生物,研究了暴露于含有亚致死剂量毒死蜱的人工土壤中8周时间内蚯蚓超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、谷胱甘肽过氧化物酶(GSH-Px)活性的变化。结果表明,毒死蜱对蚯蚓SOD、CAT、GSH-Px酶活性具有显著抑制。蚯蚓抗氧化防御系统酶对毒死蜱毒性具有一定的指示作用。除蚯蚓的LC50、产卵率、卵孵化率等常用的蚯蚓生态毒理学指标外,蚯蚓的SOD、CAT、GSH-Px抗氧化酶活性与实验农药的毒性效应具有相关性,但各指标在对毒性的响应敏感性上存在差异,其中,SOD、GSH-Px最为敏感,而CAT最不敏感。因此,在生态毒性诊断时,应选择不同指标作为一套指标体系相互补充,以增强污染诊断的灵敏性及长期诊断。     

Historical deposition of trace metals in a marine sapropel from Mangrove Lake,Bermuda with emphasis on mercury,lead, and their isotopic composition

Journal of Soils and Sediments - Sapropel is an organic-rich sediment formed under conditions that can result in sequestration of trace metals. Here, we determined the concentration of total...     

Effects of elevated atmospheric CO2 concentrations on the quantitative protein composition of wheat grain

The continuing increase in atmospheric CO 2 concentration is predicted to enhance biomass production and to alter biochemical composition of plant tissues. In the present study, winter wheat ( Triticum aestivum L. cv. 'Batis') was grown under ambient air (BLOW, CO 2 concentration: 385 muL L (-1)) and free-air CO 2 enrichment (FACE, CO 2 concentration: 550 muL l (-1)) and two different nitrogen (N) fertilization levels (normal N supply: N100, 50% of normal N supply: N50). Mature kernels were milled into white flour and analyzed for the contents of crude protein, Osborne fractions, single gluten protein types and glutenin macropolymer. Elevated CO 2 caused significant reductions in crude protein and all protein fractions and types ( p < 0.001) except albumins and globulins. Effects were more pronounced in wheat samples supplied with normal amounts of N fertilizer. Crude protein was reduced by 14% (N100) and 9% (N50), gliadins by 20% and 13%, glutenins by 15% and 15% and glutenin macropolymer by 19% and 16%, respectively. Within gliadins, omega5-gliadins (-35/-22%) and omega1,2-gliadins (-27/-14%) were more affected than alpha-gliadins (-21/-13%) and gamma-gliadins (-16/-12%). Within glutenins, HMW subunits (-23/-18%) were more affected than LMW subunits (-12/-15%). According to these results, flour from high CO 2 grown grain will have a diminished baking quality. To our knowledge, these are the first results of elevated CO 2 concentrations impacts on wheat grain protein composition gained under relevant growing conditions at least for Central Europe.