60 research outputs found
Perfluorinated Compounds in Surface Water and Organisms from Baiyangdian Lake in North China: Source Profiles, Bioaccumulation and Potential Risk
No full textThe concentrations of 16 perfluorinated compounds (PFCs) were measured in surface water and organisms from Baiyangdian Lake. Perfluorooctanoic acid (PFOA), perfluorooctane sulfonic acid, and perfluorobutanoic acid (PFBA) were the major PFC species in the water at 6.8-56.8, 0.1-17.5 and 3.0-14.6 ng/L, respectively. The PFC contamination in Baiyangdian Lake was significantly impacted by the inflow from Pinghe River and Fuhe River. There was no significant correlation between the concentrations of PFCs and the trophic levels in aquatic organisms. There were no significant PFC risks in Baiyangdian Lake according to the risk assessment of PFCs in water
Siobla zhangi Wei 2005
No full textSiobla zhangi Wei, 2005 (Plate 8) Siobla zhangi Wei, in Wei & Xiao 2005, 477– 478, Ψ Siobla nanlingia Wei, in Wei & Xiao 2005, 479– 480, ♂. New synonym. Variability: The size of the black macula in abdominal tergite in female varies from large to small or may even be absent in some specimens; the posterior margin of the 3 rd and the 4 th abdominal tergites black in some specimens. Specimens examined: Ψ, Holotype, Mt. Long, Lianyuan, Hunan, 11 May, 1999, XIAO Wei leg.; 5 ΨΨ, Paratype, Mt. Long, Lianyuan, Hunan, 11 May, 1999, ZHANG Kai-Jian leg.; 1 Ψ, Paratype, Pinghe-Linjiang, Xishui, Guizhou, alt. 800–1500m, 2 June, 2000, XIAO Wei leg.; 1 Ψ, Mt. Fanjing, Guizhou, 14 May, 1988, WU Hong leg.; 1 Ψ, Mt. Tianmu, Zhejiang, 6 July, 1963, JIN Gen-Tao leg.; 2 ΨΨ, Mt. Shunhuang, Yongzhou, Hunan, alt. 800–1000m, 27 Apr., 2004, ZHANG Shao-Bing, LIN Yang leg.; 1 Ψ, Mt. Shunhuang, Yongzhou, Hunan, alt. 800–1200m, 27 Apr., 2004, ZHOU Hu leg. 8 ɗɗ, Mt. Long, Lianyuan, Hunan, 11 May, 1999, XIAO Wei & ZHANG Kai-Jian leg. (paratype of S. nanlingia); 1 ɗ, Pinghe-Linjiang, Xishui, Guizhou, alt. 800–1500m, 2 June, 2000, XIAO Wei leg. (paratype of S. nanlingia); 3 ɗɗ, Taoyuandong, Yanling, Hunan, 24 April, 1999, WEI Mei-Cai leg. (paratype of S. nanlingia); 1 Ψ, Gouli, Mt. Mufu, Hunan (28 ° 57.939´N, 113 ° 49.711´E), alt. 860m, 21 May, 2008, LIU Fei leg.. Distribution: China (Guizhou, Hunan, Zhejiang). Note: The male of S. nanlingia Wei, 2005 is undoubtedly the undescribed male of S. zhangi Wei, 2005 based on new material, but the only paratype female of S. nanlingia is an undescribed species of the formosana group.Published as part of Niu, Gengyun & Wei, Meicai, 2010, Revision of the Siobla annulicornis, acutiscutella and sheni groups (Hymenoptera: Tenthredinidae), pp. 45-65 in Zootaxa 2643 on page 61, DOI: 10.5281/zenodo.19864
An improvement in the small-volume technique for determining thorium-234 in seawater
No full textAuthor Posting. © The Authors, 2005. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine Chemistry 100 (2006): 282-288, doi:10.1016/j.marchem.2005.10.016.The recently developed 2‐5 L small‐volume MnO2 coprecipitation method for
determining 234Th in seawater has provided a new way to substantially increase, both
temporally and spatially, the sampling resolution of 234Th and 234Th‐based particulate
organic carbon export estimates in the upper ocean. In this study, we further optimize
the technique by reducing reagent quantities and the use of an additional water bath
heating step. This optimization allows the filtration of the MnO2 precipitate onto a
25‐mm diameter, 1.0 μm pore size QMA filter to be completed within < 30 minutes for
unfiltered waters from the South China Sea. In addition, we have modified the MnO2
purification procedure to allow for alpha spetrometric measurements of 234Th recoveries.
Results from recovery experiments suggest that reagent amounts can be reduced to
0.0375 mg KMnO4 and 0.1 mg MnCl2∙4H2O per liter of sample, while still maintaining
high 234Th recovery. This study further confirms that the addition of a yield monitor is
necessary for the application of this small‐volume method.Support for this work came from the Natural Science Foundation of China through grants
#40206011, #49825162, and #90211020. This study was also supported by the China Ministry of
Education through a program for Changjiang Scholars and Innovative Research Teams in
Universities (PRSIRT)
Additional file 1 of Soil pH: a key edaphic factor regulating distribution and functions of bacterial community along vertical soil profiles in red soil of pomelo orchard
No full textAdditional file 1: Supplementary Figure S1. The relative abundance of the bacterial communities at the phylum level in different soil profiles. The least significant test (LSD test, P<0.05) was applied to check the significance of bacterial relative abundance between the different groups. Supplementary Figure S2. Functional analysis of bacterial communities on the basis of % OTUs. The symbol M represents the module, and contains a set of OTUs. Supplementary Table S1. The intensive application of N. P. K in Pinghe County
Radionuclides measured on 37 water bottle profiles during POLARSTERN cruise ARK-XXII/2
No full textThe loss of Arctic sea ice has accelerated in recent years. With the decline in sea ice cover, the Arctic Ocean biogeochemistry is undergoing unprecedented change. A key question about the changing Arctic Ocean biogeochemistry is concerning the impact of the shrinking sea ice cover on the particulate organic carbon (POC) export from the upper Arctic Ocean. Thus far, there are still very few direct measurements of POC export in the permanently ice-covered central Arctic Ocean. A further issue is that the magnitude of the POC export so far documented in this region remains controversial. During the ARK-XXII/2 expedition to the Arctic Ocean from 28 July to 7 October in 2007, we conducted a high-resolution study of POC export using 234Th/238U disequilibrium. Depth profiles of total 234Th in the upper 200 m were collected at 36 stations in the central Arctic Ocean and its adjacent seas, i.e., the Barents Sea, the Kara Sea and the Laptev Sea. Samples were processed using a small-volume MnO2 coprecipitation method with addition of a yield tracer, which resulted in one of the most precise 234Th data sets ever collected. Thorium-234 deficit with respect to 238U was found to be evident throughout the upper 100 m over the Arctic shelves. In comparison, 234Th deficit was confined to the upper 25 m in the central Arctic Ocean. Below 25 m, secular equilibrium was approached between 234Th and 238U. The observed 234Th deficit was generally associated with enhanced total chlorophyll concentrations, indicating that in situ production and export of biogenic particles are the main mechanism for 234Th removal in the Arctic Ocean. Thorium-234-derived POC fluxes were determined with a steady state model and pump-normalized POC/234Th ratios on total suspended particles collected at 100 m. Results showed enhanced POC export over the Arctic shelves. On average, POC export fluxes over the various Arctic shelves were 2.7 ± 1.7 mmol m**-2 d**-1 (the Barents Sea), 0.5 ± 0.8 mmol m**-2 d**-1 (the Kara Sea), and 2.9 ± 1.8 mmol m**-2 d**-1 (the Laptev Sea) respectively. In comparison, the central Arctic Ocean was characterized by the lowest POC export flux ever reported, 0.2 ± 1.0 mmol m**-2 d**-1 (1 standard deviation, n = 26). This value is very low compared to prior estimates and is also much lower than the POC export fluxes reported in other oligotrophic oceans. A ThE ratio (234Th-derived POC export/primary production) of <6% in the central Arctic Ocean was estimated using the historical measurements of primary production. The low ThE ratio indicates that like other oligotrophic regimes, the central Arctic Ocean is characterized by low POC export relative to primary production, i.e., a tightly coupled food web. Our study strongly suggests that the current role of the central Arctic Ocean in C sequestration is still very limited. Meanwhile, this role might be altered because of global warming and future decline in sea ice cover
Comment on “How accurate are234Th measurements in seawater based on the MnO2-impregnated cartridge technique?” by Pinghe Cai et al.
No full text
Calibration of RaDeCC systems for Ra-223 measurements
No full textUS National Science Foundation [OCE-0926559, OCE-1231211]; National Basic Research Program ("973" Program) of China [2009CB421203]; Natural Science Foundation of China (NSFC) [41076041]; National Natural Science Foundation of China [41121091]RaDeCC (or radium delayed coincidence) counters have proved to be a fast and precise way to measure Ra-224 and Ra-223 in water samples. However, the calibration of these counters for Ra-223 has been problematic. Unlike standards prepared from Th-232 to calibrate Ra-224-Rn-220 measurements, standards prepared from (227)AC for Ra-223-Rn-219 measurements decrease in the amount of Rn-219 they release with time. Here we develop a way to use the Th-232 calibration of the 220 channel efficiency to calibrate the 219 channel. We first consider the slightly different effects of delay and window opening time constants in the default RaDeCC system. These differences favor Rn-220 detection by about 3%. Next, we consider the effect of dead volume on the relative efficiencies. In a typical system, with a source volume in the range 100-300 ml, there is about a 3 similar to 8% lower predicted probability of Rn-219 decaying in the counting cell relative to Rn-220. Thus, the absolute efficiency of the 219 channel should be about 6-11% lower than the efficiency of the 220 channel, depending on the dead volume of the system. We tested the effects of window time constants and dead volumes by altering these parameters in a known manner and correcting for the alterations. In this analysis we neglect the differences in alpha decay energy between the Rn-219-Po-215 pair and the Rn-220-Po-216 pair. These differences may increase slightly the efficiency of the 219 channel because of the higher alpha decay energies of Rn-219-(215)po. (C) 2013 Elsevier B.V. All rights reserved
Physical oceanography, pacific water fraction, river water fraction, 224Ra, 226Ra, and 228Ra measured on water samples taken with the in-situ pump system during POLARSTERN cruise ARK-XXII/2
No full textPhysical oceanography, pacific water fraction, river water fraction, 224Ra, 226Ra, and 228Ra measured on water samples taken with the in-situ pump system during POLARSTERN cruise ARK-XXII/
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