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Lihai Shang - One of the best experts on this subject based on the ideXlab platform.
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mercury distribution and speciation in water and fish from abandoned hg mines in wanshan guizhou province china
Science of The Total Environment, 2009Co-Authors: Guangle Qiu, Xinbin Feng, Shaofeng Wang, Lihai ShangAbstract:Concentrations of total mercury (Hg-T), methylmercury (MeHg), and its speciation in water samples as well as fish collected from abandoned Hg mines in Wanshan, Guizhou province, China, were measured to show regional dispersion of Hg contaminations that are not well known. High Hg-T and MeHgT (total methylmercury) concentrations obtained in waters from miniNg areas, raNged from 15 to 9300 Ng/l and 0.31 to 25 Ng/l, respectively. MeHgT were not correlated with Hg-T, whereas, peak values in both cases were in accord with high concentrations of particulate fraction, which appeared to be enhanced duriNg high-flow regime with ratios reachiNg to 99%. Elevated Hg concentrations in the particulate form indicated that particles released from Hg miniNg tailiNgs (calcines) might be an important pathway of Hg to the aquatic system. The concentrations of total Hg in fish muscle were elevated raNgiNg from 0.061 to 0.68 mg/kg, but MeHg were generally low raNgiNg from 0.024 to 0.098 mg/kg with a mean ratio of 28%. The concentrations and distribution patterns of Hg in aquatic systems suggested derivation from historic Hg miniNg sites in the Wanshan area. (C) 2009 Elsevier B.V. All rights reserved.
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the variations of mercury in sediment profiles from a historically mercury contaminated reservoir guizhou province china
Science of The Total Environment, 2008Co-Authors: Haiyu Yan, Xinbin Feng, Shaofeng Wang, Lihai Shang, Guangle Qiu, Qianjin Dai, Yamin HouAbstract:Abstract Baihua Reservoir in Guizhou Province, China, experienced serious Hg contamination from Guizhou Organic Chemical Plant (GOCP) between 1971 and 1997. However, the biogeochemical cycliNg of Hg in this reservoir is not well studied. Sediment cores were collected in fall 2002, spriNg 2003 and in spriNg and fall 2004. THg and MeHg concentrations in all sediment profiles raNged from 0.26 to 38.9 mg/kg and from 0.5 to 27.5 μg/kg (d.w.), respectively. The distribution of THg in sediment cores was characterized by a few peaks, which may correspond to the Hg-containiNg wastewater discharge history of the GOCP. The average THg concentrations in sediments cores decreased from upstream to downstream due to the deposition of particulate Hg, which is the major form of Hg in water. THg and MeHg concentrations in pore water varied from 6.1 to 5860 Ng/L and from 0.3 to 15.4 Ng/L, respectively, which were significantly higher than levels in the overlyiNg water column. Average diffusive flux from sediment to water is 1642 and 36 Ng/m 2 /day for THg and MeHg. The spatial distribution of THg in pore water from upstream to downstream showed the same trend as the sediment, but MeHg in pore water did not show a decliniNg pattern with distance from the GOCP. These results suggested that sediments experienced serious contamination of Hg, and the contaminated sediment is an important Hg contamination source to the overlyiNg water.
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mercury pollution from artisanal mercury miniNg in toNgren guizhou china
Applied Geochemistry, 2008Co-Authors: Xinbin Feng, Lihai Shang, Guangle Qiu, Bo Meng, Peng Liang, Hua ZhangAbstract:Abstract Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the ToNgren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg miniNg. Mine waste contained high T-Hg concentrations, raNgiNg from 1.8 to 900 mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirmiNg that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the bindiNg and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44 mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varyiNg from 92 to 2300 Ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9 Ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg miniNg in the study area, but the extent of Hg contamination is dependent on the miniNg history and the scale of artisanal Hg miniNg.
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environmental contamination of mercury from hg miniNg areas in wuchuan northeastern guizhou china
Environmental Pollution, 2006Co-Authors: Xinbin Feng, Shaofeng Wang, Lihai ShangAbstract:Total Hg and methyl-Hg were evaluated in mine wastes, soils, water, and vegetations from the Wuchuan Hg-miniNg areas, Guizhou, China. Mine wastes contain high total Hg concentrations, raNgiNg from 79 to 710 m gg � 1 , and methyl-Hg from 0.32 to 3.9 Ng g � 1 . Total Hg in soil samples raNge from 0.33 to 320 m gg � 1 and methyl-Hg from 0.69 to 20 Ng g � 1 . Vegetations present a high average total Hg concentration of 260 Ng g � 1 , which greatly exceeds the maximum Hg concentration of 20 Ng g � 1 recommended by the Chinese National Standard Agency for food sources. The rice samples contain elevated methyl-Hg concentrations, raNgiNg from 4.2 to 18 Ng g � 1 . Stream water collected from Hg-miniNg areas is also contaminated, containiNg Hg as high as 360 Ng l � 1 , and methyl-Hg reaches up to 5.7 Ng l � 1 . Data indicate heavy
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mercury and methylmercury in riparian soil sediments mine waste calcines and moss from abandoned hg mines in east guizhou province southwestern china
Applied Geochemistry, 2005Co-Authors: Xinbin Feng, Shaofeng Wang, Lihai ShangAbstract:Abstract Concentrations of total Hg and methylmercury (MMHg) in riparian soil, mine-waste calcine, sediment, and moss samples collected from abandoned Hg mines in Wanshan district, Guizhou province, China, were measured to show regional dispersion of Hg-contamination. High total Hg and MMHg concentrations obtained in riparian soils from mined areas, raNged from 5.1 to 790 mg kg −1 and 0.13 to 15 Ng g −1 , respectively. However, total Hg and MMHg concentrations in the soils collected from control sites were significantly lower varyiNg from 0.1 to 1.2 mg kg −1 and 0.10 to 1.6 Ng g −1 , respectively. Total Hg and MMHg concentrations in sediments varied from 90 to 930 mg kg −1 and 3.0 to 20 Ng g −1 , respectively. Total Hg concentrations in mine-waste calcines were highly elevated raNgiNg from 5.7 to 4400 mg kg −1 , but MMHg concentrations were generally low raNgiNg from 0.17 to 1.1 Ng g −1 . Similar to the high Hg concentrations in soil and sediments, moss samples collected from rocks raNged from 1.0 to 95 mg kg −1 in total Hg and from 0.21 to 20 Ng g −1 in MMHg. Elevated Hg concentrations in mosses suggest that atmospheric deposition might be an important pathway of Hg to the local terrestrial system. Moreover, the spatial distribution patterns of Hg contamination in the local environment suggest derivation from historic Hg miniNg sites in the Wanshan area.
Xinbin Feng - One of the best experts on this subject based on the ideXlab platform.
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environmental geochemistry of an abandoned mercury mine in yanwupiNg guizhou province china
Environmental Research, 2013Co-Authors: Guangle Qiu, Xinbin Feng, Bo Meng, Chao Zhang, Yan LinAbstract:Abstract The distribution of mercury (Hg) and methylmercury (MeHg) in paddy soil and rice grain (polished), and Hg in surface waters and gaseous elemental Hg (GEM) in atmosphere at the YanwupiNg Hg miniNg district (YMM), Guizhou Province, China was investigated. Results exhibited high total Hg (Hg T ) and MeHg concentrations in soil at sites adjacent to calcine pile and tailiNgs, and raNged from 5.6 to 240 mg kg −1 and 0.66 to 7.3 μg kg −1 , respectively. Concentrations of Hg T in rice raNged from 10 to 45 μg kg −1 , and high MeHg concentrations were also observed raNgiNg from 3.2 to 39 μg kg −1 . The elevated Hg T and MeHg concentrations in soil in the vicinity of calcine pile and tailiNgs reflected in high MeHg concentrations in rice. Those data were significantly correlated with MeHg concentration in soil confirmiNg that soil is the major source of MeHg in rice. The highest Hg concentrations in water, otherwise rather low, raNgiNg from 3.8 to 51 Ng l −1 for Hg T and of 0.14 to 2.7 Ng l −1 for MeHg T , were found at the proximity of calcine pile suggestiNg that untreated mine wastes are the principal source of Hg in the nearby area. Huge emissions of GEM were also detected from calcines affectiNg the whole area, raNgiNg from 12 to 180 Ng m −3 with an average of 46±35 Ng m −3 . The distribution patterns of Hg and MeHg observed in the environmental compartments suggest an elevated contamination of Hg in the region. Elevated high MeHg concentrations in rice might pose a potential health risk to local populations.
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insights into low fish mercury bioaccumulation in a mercury contaminated reservoir guizhou china
Environmental Pollution, 2012Co-Authors: Bian Liu, Xinbin Feng, Haiyu Yan, Cuiping Wang, Stephane Guedron, Jorge E Spangenberg, Janusz DominikAbstract:We examined Hg biogeochemistry in Baihua Reservoir, a system affected by industrial wastewater containiNg mercury (Hg). As expected, we found high levels of total Hg (THg, 664-7421 Ng g(-1)) and monomethylmercury (MMHg, 3-21 Ng g(-1)) in the surface sediments (0-10 cm). In the water column, both THg and MMHg showed stroNg vertical variations with higher concentrations in the anoxic layer (>4m) than in the oxic layer (0-4 m), which was most pronounced for the dissolved MMHg (p < 0.001). However, mercury levels in biota samples (mostly cyprinid fish) were one order of magnitude lower than common regulatory values (i.e. 0.3-0.5 mg kg(-1)) for human consumption. We identified three main reasons to explain the low fish Hg bioaccumulation: disconnection of the aquatic food web from the high MMHg zone, simple food web structures, and biodilution effect at the base of the food chain in this eutrophic reservoir.
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mercury distribution and speciation in water and fish from abandoned hg mines in wanshan guizhou province china
Science of The Total Environment, 2009Co-Authors: Guangle Qiu, Xinbin Feng, Shaofeng Wang, Lihai ShangAbstract:Concentrations of total mercury (Hg-T), methylmercury (MeHg), and its speciation in water samples as well as fish collected from abandoned Hg mines in Wanshan, Guizhou province, China, were measured to show regional dispersion of Hg contaminations that are not well known. High Hg-T and MeHgT (total methylmercury) concentrations obtained in waters from miniNg areas, raNged from 15 to 9300 Ng/l and 0.31 to 25 Ng/l, respectively. MeHgT were not correlated with Hg-T, whereas, peak values in both cases were in accord with high concentrations of particulate fraction, which appeared to be enhanced duriNg high-flow regime with ratios reachiNg to 99%. Elevated Hg concentrations in the particulate form indicated that particles released from Hg miniNg tailiNgs (calcines) might be an important pathway of Hg to the aquatic system. The concentrations of total Hg in fish muscle were elevated raNgiNg from 0.061 to 0.68 mg/kg, but MeHg were generally low raNgiNg from 0.024 to 0.098 mg/kg with a mean ratio of 28%. The concentrations and distribution patterns of Hg in aquatic systems suggested derivation from historic Hg miniNg sites in the Wanshan area. (C) 2009 Elsevier B.V. All rights reserved.
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the variations of mercury in sediment profiles from a historically mercury contaminated reservoir guizhou province china
Science of The Total Environment, 2008Co-Authors: Haiyu Yan, Xinbin Feng, Shaofeng Wang, Lihai Shang, Guangle Qiu, Qianjin Dai, Yamin HouAbstract:Abstract Baihua Reservoir in Guizhou Province, China, experienced serious Hg contamination from Guizhou Organic Chemical Plant (GOCP) between 1971 and 1997. However, the biogeochemical cycliNg of Hg in this reservoir is not well studied. Sediment cores were collected in fall 2002, spriNg 2003 and in spriNg and fall 2004. THg and MeHg concentrations in all sediment profiles raNged from 0.26 to 38.9 mg/kg and from 0.5 to 27.5 μg/kg (d.w.), respectively. The distribution of THg in sediment cores was characterized by a few peaks, which may correspond to the Hg-containiNg wastewater discharge history of the GOCP. The average THg concentrations in sediments cores decreased from upstream to downstream due to the deposition of particulate Hg, which is the major form of Hg in water. THg and MeHg concentrations in pore water varied from 6.1 to 5860 Ng/L and from 0.3 to 15.4 Ng/L, respectively, which were significantly higher than levels in the overlyiNg water column. Average diffusive flux from sediment to water is 1642 and 36 Ng/m 2 /day for THg and MeHg. The spatial distribution of THg in pore water from upstream to downstream showed the same trend as the sediment, but MeHg in pore water did not show a decliniNg pattern with distance from the GOCP. These results suggested that sediments experienced serious contamination of Hg, and the contaminated sediment is an important Hg contamination source to the overlyiNg water.
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mercury pollution from artisanal mercury miniNg in toNgren guizhou china
Applied Geochemistry, 2008Co-Authors: Xinbin Feng, Lihai Shang, Guangle Qiu, Bo Meng, Peng Liang, Hua ZhangAbstract:Abstract Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the ToNgren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg miniNg. Mine waste contained high T-Hg concentrations, raNgiNg from 1.8 to 900 mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirmiNg that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the bindiNg and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44 mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varyiNg from 92 to 2300 Ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9 Ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg miniNg in the study area, but the extent of Hg contamination is dependent on the miniNg history and the scale of artisanal Hg miniNg.
Gilbert Pepin - One of the best experts on this subject based on the ideXlab platform.
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determination of endogenous levels of ghb in human hair are there possibilities for the identification of ghb administration through hair analysis in cases of drug facilitated sexual assault
Journal of Analytical Toxicology, 2003Co-Authors: Jean Pierre Goulle, Marjorie Cheze, Gilbert PepinAbstract:We have developed a GC-MS-MS assay for GHB in human hair. Five milligrams of washed hair were bydrolyzed by 1M or 0.01M NaOH before a liquid-liquid extraction with ethyl acetate under acidic conditions. GHB-d6 was used as the internal standard. TMS derivatives were formed before injection. TBDMS derivatives were used in cases of stroNg chromatographic interferences or in a confirmatory procedure. Analysis of basal levels of GHB in 61 drug-free donors gave the followiNg results: the mean measured concentration for blond hair was 0.60 Ng/mg (n = 12), SD = 0.19 Ng/mg, and extreme figures were in the raNge 0.35-0.95 Ng/mg. For brown hair, the mean measured concentration was 0.90 Ng/mg (n = 30), SD = 0.42 Ng/mg, and extreme figures 0.41-1.86 Ng/mg. For black hair, the mean measured concentration was 0.90 Ng/mg (n = 19), SD = 0.37 rig/rag, and extreme figures 0.32-1.54 Ng/mg, showiNg no significant differences dependiNg on hair color. Analysis of basal levels of GHB of 12 or more specimens in segmented hair showed a mean concentration of 1.22 Ng/mg (0.31-8.4 Ng/mg) and a relative standard deviation for each individual raNgiNg from 6.75% to 37.98%. GHB was administered to a healthy 53-year-old white male (light brown hair) at oral dosages of 30, 45, and 60 mg/kg. Beard hair was collected just before administration and 24 h after (and each day for one week for the last dose), and a 7.5-cm scalp hair lock was collected 7 days after the last dose. A rise in GHB concentration was observed in beard hair for the 45 and 60 mg/kg dosages with a maximum at 24 h, whereas no chaNge was observed for the 30 mg/kg dosage. Scalp hair was segmented into 3-ram loNg segments. The three proximal
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determination of endogenous levels of ghb in human hair are there possibilities for the identification of ghb administration through hair analysis in cases of drug facilitated sexual assault
Journal of Analytical Toxicology, 2003Co-Authors: Jean Pierre Goulle, Marjorie Cheze, Gilbert PepinAbstract:We have developed a GC-MS-MS assay for GHB in human hair. Five milligrams of washed hair were hydrolyzed by 1M or 0.01M NaOH before a liquid-liquid extraction with ethyl acetate under acidic conditions. GHB-d(6) was used as the internal standard. TMS derivatives were formed before injection. TBDMS derivatives were used in cases of stroNg chromatographic interferences or in a confirmatory procedure. Analysis of basal levels of GHB in 61 drug-free donors gave the followiNg results: the mean measured concentration for blond hair was 0.60 Ng/mg (n = 12), SD = 0.19 Ng/mg, and extreme figures were in the raNge 0.35-0.95 Ng/mg. For brown hair, the mean measured concentration was 0.90 Ng/mg (n = 30), SD = 0.42 Ng/mg, and extreme figures 0.41-1.86 Ng/mg. For black hair, the mean measured concentration was 0.90 Ng/mg (n = 19), SD = 0.37 Ng/mg, and extreme figures 0.32-1.54 Ng/mg, showiNg no significant differences dependiNg on hair color. Analysis of basal levels of GHB of 12 or more specimens in segmented hair showed a mean concentration of 1.22 Ng/mg (0.31-8.4 Ng/mg) and a relative standard deviation for each individual raNgiNg from 6.75% to 37.98%. GHB was administered to a healthy 53-year-old white male (light brown hair) at oral dosages of 30, 45, and 60 mg/kg. Beard hair was collected just before administration and 24 h after (and each day for one week for the last dose), and a 7.5-cm scalp hair lock was collected 7 days after the last dose. A rise in GHB concentration was observed in beard hair for the 45 and 60 mg/kg dosages with a maximum at 24 h, whereas no chaNge was observed for the 30 mg/kg dosage. Scalp hair was segmented into 3-mm loNg segments. The three proximal last segments showed significantly (0.0005 < p < 0.005) different concentrations of GHB (1.22, 1.27, and 1.66 Ng/mg, respectively) when compared with the basal physiological level of GHB in this same person (mean = 0.62 Ng/mg, SD = 0.15 Ng/mg). A case of daily GHB abuse duriNg bodybuildiNg allowed us to determine a concentration of GHB of 14 Ng/mg, in a 2-cm loNg segment (black hair). A case of rape under the influence of GHB was documented through hair analysis (black hair) and positive analysis of the glass she used. Sampled 7 days after the sexual assault, the three last 3-mm loNg proximal segments tested for GHB exhibited concentrations of 3.1-5.3 and 4.3 Ng/mg, respectively, whereas the mean physiological level determined in this woman was 0.71 Ng/mg, SD = 0.17 Ng/mg. The authors advise a two-step hair sampliNg as evidence of GHB consumption: the first sample at the time of exposure to show the contamination by sweat of the proximal segment in case of recent administration with a significant rise of hair level at the root, and the second after at least 3 or 4 weeks to avoid this contamination and determine the levels incorporated in the hair matrix before, duriNg, and after the exposure.
Thomas Unger - One of the best experts on this subject based on the ideXlab platform.
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effects of orally applied candesartan cilexetil on central responses to aNgiotensin ii in conscious rats
Journal of Hypertension, 2002Co-Authors: Peter Gohlke, T. Jürgensen, S. Von Kügelgen, Wolfgang Rascher, Juraj Culman, Thomas UngerAbstract:OBJECTIVE: In the present study, we investigated the ability of the peripherally administered aNgiotensin II type 1 (AT1) receptor antagonist, candesartan cilexetil, to block central effects of aNgiotensin II (ANg II) in conscious rats. DESIGN AND METHODS: Candesartan cilexetil was administered orally by gavage at doses of 0.1, 1, 10 and 30 mg/kg. DrinkiNg response, pressor response and release of vasopressin into the circulation followiNg intracerebroventricular (i.c.v.) ANg II (10 or 100 Ng) were measured at 0.5, 2, 4 and 24 h followiNg the drug application. The same parameters were measured after chronic treatment with candesartan cilexetil for 1 week. In a separate experiment, the release of vasopressin induced by microinjection of ANg II (100 Ng) into the paraventricular nucleus (PVN) was determined 4 h after oral administration of candesartan cilexetil (1 mg/kg) or vehicle. RESULTS: Oral treatment with candesartan cilexetil inhibited all central responses to i.c.v. ANg II in a dose- and time-dependent manner. The ANg II-induced responses were inhibited 4 h after acute or chronic treatment with 0.1 mg/kg candesartan cilexetil, but had returned to control levels 24 h after drug application. In contrast, the highest dose of candesartan cilexetil (30 mg/kg) nearly abolished the central responses to ANg II for 24 h. Candesartan cilexetil completely blocked vasopressin release into the circulation induced by ANg II microinjection into the PVN. CONCLUSIONS: Our results demonstrate that the AT1 receptor antagonist, candesartan cilexetil, very effectively inhibits the centrally mediated effects of ANg II upon peripheral application.
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at1 receptor antagonist telmisartan administered peripherally inhibits central responses to aNgiotensin ii in conscious rats
Journal of Pharmacology and Experimental Therapeutics, 2001Co-Authors: Peter Gohlke, Wolfgang Rascher, Juraj Culman, S Weiss, A Jansen, W Wienen, J Stangier, Thomas UngerAbstract:The effects of systemic treatment with the AT1 receptor antagonist telmisartan on central effects of aNgiotensin II (ANg II), namely, increase in blood pressure, vasopressin release into the circulation, and drinkiNg response, were investigated in conscious, normotensive rats. The central responses to i.c.v. ANg II (30 Ng/kg) were measured at 0.5, 2, 4, and 24 h followiNg acute i.v. or acute and chronic oral telmisartan application. At a dose of 10 mg/kg i.v., the drinkiNg response to i.c.v. ANg II was completely blocked over 4 h, while the pressor response and the release of vasopressin in response to i.c.v. ANg II were blocked by 60 to 80%. The inhibition of the centrally mediated pressor and drinkiNg response to ANg II was sustained over 24 h. The lower doses of telmisartan (0.3 and 1 mg/kg) significantly inhibited the ANg II-induced actions over 4 h. A consistent 24-h inhibition of the central responses to i.c.v. ANg II was obtained after acute and chronic oral treatment with 30 mg/kg telmisartan. Oral treatment with 1 and 3 mg/kg telmisartan produced a slight but inconsistent inhibition of the central actions of ANg II. Telmisartan concentrations measured in the cerebrospinal fluid followiNg 8 days of consecutive daily oral treatment (1-30 mg/kg) raNged from 0.87 +/- 0.27 Ng/ml (1 mg/kg/day) to 46.5 +/- 11.6 Ng/ml (30 mg/kg/day). Our results demonstrate that, followiNg peripheral administration, the AT1 receptor antagonist telmisartan can penetrate the blood-brain barrier in a dose- and time-dependent manner to inhibit centrally mediated effects of ANg II.
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at2 receptor stimulation increases aortic cyclic gmp in shrsp by a kinin dependent mechanism
Hypertension, 1998Co-Authors: Peter Gohlke, Christiane Pees, Thomas UngerAbstract:In the present study we tested the hypothesis whether an aNgiotensin AT 2 receptor-mediated stimulation of the bradykinin (BK)/nitric oxide (NO) system can account for the effects of AT 1 receptor antagonism on aortic cGMP described previously in SHRSP. Adult SHRSP were treated for 4 hours with aNgiotensin II (ANg II) (30 Ng/kg per min IV) or vehicle (0.9% NaCl IV). Animals were pretreated with vehicle, losartan (100 mg/kg PO), PD 123319 (30 mg/kg IV), losartan plus PD 123319, icatibant (500 μg/kg IV), N G -nitro-l-arginine methyl ester (L-NAME; 1 mg/kg IV), or minoxidil (3 mg/kg IV). Mean arterial blood pressure (MAP) was continuously monitored over the 4-hour experimental period, and plasma ANg II and aortic cGMP were measured by RIA at the end of the study. ANg II infusion over 4 hours raised MAP by about 20 mm Hg. Losartan alone or losartan plus ANg II as well as minoxidil plus ANg II markedly reduced blood pressure when compared to vehicle-treated or ANg II-treated animals, respectively. Plasma levels of ANg II were increased 2-fold by ANg II infusion alone or by ANg II in combination with icatibant, L-NAME, or minoxidil. The increase in plasma ANg II levels was even more pronounced after losartan treatment. Aortic cGMP content was significantly increased by ANg II, losartan, losartan plus ANg II, and minoxidil plus ANg II by 60%, 45%, 68%, and 52%, respectively ( P 2 receptor antagonist PD 123319. Icatibant and L-NAME abolished the effects of ANg II on aortic cGMP. Our results demonstrate the followiNg: (1) ANg II increases aortic cGMP by an AT 2 receptor-mediated action because the effect could be prevented by an AT 2 receptor antagonist; (2) the effect of ANg II was not secondary to blood pressure increase because it remained under reduction of MAP with minoxidil; (3) losartan increased aortic cGMP most likely by increasiNg plasma ANg II levels with a subsequent stimulation of AT 2 receptors; and (4) the effects of AT 2 receptor stimulation are mediated by BK and, subsequently, NO because they were abolished by B 2 receptor blockade as well as by NO synthase inhibition.
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at2 receptor stimulation increases aortic cyclic gmp in shrsp by a kinin dependent mechanism
Hypertension, 1998Co-Authors: Peter Gohlke, Christiane Pees, Thomas UngerAbstract:In the present study we tested the hypothesis whether an aNgiotensin AT2 receptor-mediated stimulation of the bradykinin (BK)/nitric oxide (NO) system can account for the effects of AT1 receptor antagonism on aortic cGMP described previously in SHRSP. Adult SHRSP were treated for 4 hours with aNgiotensin II (ANg II) (30 Ng/kg per min IV) or vehicle (0.9% NaCl I.V.). Animals were pretreated with vehicle, losartan (100 mg/kg P.O.), PD 123319 (30 mg/kg I.V.), losartan plus PD 123319, icatibant (500 microg/kg I.V.), N(G)-nitro-L-arginine methyl ester (L-NAME; 1 mg/kg I.V.), or minoxidil (3 mg/kg I.V.). Mean arterial blood pressure (MAP) was continuously monitored over the 4-hour experimental period, and plasma ANg II and aortic cGMP were measured by RIA at the end of the study. ANg II infusion over 4 hours raised MAP by about 20 mm Hg. Losartan alone or losartan plus ANg II as well as minoxidil plus ANg II markedly reduced blood pressure when compared to vehicle-treated or ANg II-treated animals, respectively. Plasma levels of ANg II were increased 2-fold by ANg II infusion alone or by ANg II in combination with icatibant, L-NAME, or minoxidil. The increase in plasma ANg II levels was even more pronounced after losartan treatment. Aortic cGMP content was significantly increased by ANg II, losartan, losartan plus ANg II, and minoxidil plus ANg II by 60%, 45%, 68%, and 52%, respectively (P<.05). The effects of ANg II and of losartan plus ANg II on aortic cGMP content were both blocked by cotreatment with the AT2 receptor antagonist PD 123319. Icatibant and L-NAME abolished the effects of ANg II on aortic cGMP. Our results demonstrate the followiNg: (1) ANg II increases aortic cGMP by an AT2 receptor-mediated action because the effect could be prevented by an AT2 receptor antagonist; (2) the effect of ANg II was not secondary to blood pressure increase because it remained under reduction of MAP with minoxidil; (3) losartan increased aortic cGMP most likely by increasiNg plasma ANg II levels with a subsequent stimulation of AT2 receptors; and (4) the effects of AT2 receptor stimulation are mediated by BK and, subsequently, NO because they were abolished by B2 receptor blockade as well as by NO synthase inhibition.
Guangle Qiu - One of the best experts on this subject based on the ideXlab platform.
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environmental geochemistry of an abandoned mercury mine in yanwupiNg guizhou province china
Environmental Research, 2013Co-Authors: Guangle Qiu, Xinbin Feng, Bo Meng, Chao Zhang, Yan LinAbstract:Abstract The distribution of mercury (Hg) and methylmercury (MeHg) in paddy soil and rice grain (polished), and Hg in surface waters and gaseous elemental Hg (GEM) in atmosphere at the YanwupiNg Hg miniNg district (YMM), Guizhou Province, China was investigated. Results exhibited high total Hg (Hg T ) and MeHg concentrations in soil at sites adjacent to calcine pile and tailiNgs, and raNged from 5.6 to 240 mg kg −1 and 0.66 to 7.3 μg kg −1 , respectively. Concentrations of Hg T in rice raNged from 10 to 45 μg kg −1 , and high MeHg concentrations were also observed raNgiNg from 3.2 to 39 μg kg −1 . The elevated Hg T and MeHg concentrations in soil in the vicinity of calcine pile and tailiNgs reflected in high MeHg concentrations in rice. Those data were significantly correlated with MeHg concentration in soil confirmiNg that soil is the major source of MeHg in rice. The highest Hg concentrations in water, otherwise rather low, raNgiNg from 3.8 to 51 Ng l −1 for Hg T and of 0.14 to 2.7 Ng l −1 for MeHg T , were found at the proximity of calcine pile suggestiNg that untreated mine wastes are the principal source of Hg in the nearby area. Huge emissions of GEM were also detected from calcines affectiNg the whole area, raNgiNg from 12 to 180 Ng m −3 with an average of 46±35 Ng m −3 . The distribution patterns of Hg and MeHg observed in the environmental compartments suggest an elevated contamination of Hg in the region. Elevated high MeHg concentrations in rice might pose a potential health risk to local populations.
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mercury distribution and speciation in water and fish from abandoned hg mines in wanshan guizhou province china
Science of The Total Environment, 2009Co-Authors: Guangle Qiu, Xinbin Feng, Shaofeng Wang, Lihai ShangAbstract:Concentrations of total mercury (Hg-T), methylmercury (MeHg), and its speciation in water samples as well as fish collected from abandoned Hg mines in Wanshan, Guizhou province, China, were measured to show regional dispersion of Hg contaminations that are not well known. High Hg-T and MeHgT (total methylmercury) concentrations obtained in waters from miniNg areas, raNged from 15 to 9300 Ng/l and 0.31 to 25 Ng/l, respectively. MeHgT were not correlated with Hg-T, whereas, peak values in both cases were in accord with high concentrations of particulate fraction, which appeared to be enhanced duriNg high-flow regime with ratios reachiNg to 99%. Elevated Hg concentrations in the particulate form indicated that particles released from Hg miniNg tailiNgs (calcines) might be an important pathway of Hg to the aquatic system. The concentrations of total Hg in fish muscle were elevated raNgiNg from 0.061 to 0.68 mg/kg, but MeHg were generally low raNgiNg from 0.024 to 0.098 mg/kg with a mean ratio of 28%. The concentrations and distribution patterns of Hg in aquatic systems suggested derivation from historic Hg miniNg sites in the Wanshan area. (C) 2009 Elsevier B.V. All rights reserved.
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the variations of mercury in sediment profiles from a historically mercury contaminated reservoir guizhou province china
Science of The Total Environment, 2008Co-Authors: Haiyu Yan, Xinbin Feng, Shaofeng Wang, Lihai Shang, Guangle Qiu, Qianjin Dai, Yamin HouAbstract:Abstract Baihua Reservoir in Guizhou Province, China, experienced serious Hg contamination from Guizhou Organic Chemical Plant (GOCP) between 1971 and 1997. However, the biogeochemical cycliNg of Hg in this reservoir is not well studied. Sediment cores were collected in fall 2002, spriNg 2003 and in spriNg and fall 2004. THg and MeHg concentrations in all sediment profiles raNged from 0.26 to 38.9 mg/kg and from 0.5 to 27.5 μg/kg (d.w.), respectively. The distribution of THg in sediment cores was characterized by a few peaks, which may correspond to the Hg-containiNg wastewater discharge history of the GOCP. The average THg concentrations in sediments cores decreased from upstream to downstream due to the deposition of particulate Hg, which is the major form of Hg in water. THg and MeHg concentrations in pore water varied from 6.1 to 5860 Ng/L and from 0.3 to 15.4 Ng/L, respectively, which were significantly higher than levels in the overlyiNg water column. Average diffusive flux from sediment to water is 1642 and 36 Ng/m 2 /day for THg and MeHg. The spatial distribution of THg in pore water from upstream to downstream showed the same trend as the sediment, but MeHg in pore water did not show a decliniNg pattern with distance from the GOCP. These results suggested that sediments experienced serious contamination of Hg, and the contaminated sediment is an important Hg contamination source to the overlyiNg water.
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mercury pollution from artisanal mercury miniNg in toNgren guizhou china
Applied Geochemistry, 2008Co-Authors: Xinbin Feng, Lihai Shang, Guangle Qiu, Bo Meng, Peng Liang, Hua ZhangAbstract:Abstract Concentrations of total Hg (T-Hg) were measured in mine waste, stream water, soil and moss samples collected from the ToNgren area, Guizhou, China to identify potential Hg contamination to local environments, which has resulted from artisanal Hg miniNg. Mine waste contained high T-Hg concentrations, raNgiNg from 1.8 to 900 mg/kg. High concentrations of Hg were also found in the leachates of mine waste, confirmiNg that mine waste contains significant water-soluble Hg compounds. Total Hg distribution patterns in soil profiles showed that top soil is contaminated with Hg, which has been derived from atmospheric deposition. Data suggest that organic matter plays an important role in the bindiNg and transport of Hg in soil. Elevated T-Hg concentrations (5.9–44 mg/kg) in moss samples suggest that atmospheric deposition is the dominant source of Hg to local terrestrial ecosystems. Concentrations of T-Hg were highly elevated in stream water samples, varyiNg from 92 to 2300 Ng/L. Particulate Hg in water constituted a large proportion of the T-Hg and played a major role in Hg transport. Methyl–Hg (Me–Hg) concentrations in the water samples was as high as 7.9 Ng/L. Data indicate that Hg contamination is dominantly from artisanal Hg miniNg in the study area, but the extent of Hg contamination is dependent on the miniNg history and the scale of artisanal Hg miniNg.