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Assessing the utility of dissolved organic matter photoreactivity as a predictor of in situ methylmercury concentration

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journal of Environmental Sciences 2018年第6期30卷 160-168页

作者： Sara j.Klapstein Susan E.Ziegler David A.Risk nelson j.o'driscoll Environmental Science Program Memorial University of Newfoundland Department of Earth Sciences St. Francis Xavier University Department of Earth and Environmental Science Acadia University

Methylmercury（MeHg） bioaccumulation is a growing concern in ecosystems worldwide. The absorption of solar radiation by dissolved organic matter（DoM） and other photoreactive ligands can convert MeHg into less toxic forms of mercury through photodemethylation. In this study, spectral changes and photoreactivity of DoM were measured to assess the potential to control photoreactions and predict in situ MeHg concentration. Water samples collected from a series of lakes in southwestern Nova Scotia in june, August, and September were exposed to controlled ultraviolet-A（UV-A） radiation for up to 24 hr. Dissolved organic matter photoreactivity, measured as the loss of absorbance at 350 nm at constant UV-A irradiation, was positively dependent on the initial DoM concentration in lake waters（r^2=0.94）. This relationship was consistent over time with both DoM concentration and photoreactivity increasing from summer into fall across lakes. Lake in situ MeHg concentration was positively correlated with DoM concentration and likely catchment transport in june（r = 0.77） but not the other sampling months. Despite a consistent seasonal variation in both DoM and Fe, and their respective correlations with MeHg, no discernable seasonal trend in MeHg was observed. However, a 3-year dataset from the 6 study lakes revealed a positive correlation between DoM concentration and both Fe（r = 0.91） and MeHg concentrations（r = 0.51） suggesting a more dominant landscape mobility control on *** DoM-MeHg relationships observed in these lakes highlights the need to examine DoM photoreactivity controls on MeHg transport and availability in natural waters particularly given future climate perturbations.

关键词： Methylmercury Dissolved organic carbon Photoreactions Kejimkujik National Park Freshwater lakes

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Mercury photoreduction and photooxidation in lakes：Effects of filtration and dissolved organic carbon concentration

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journal of Environmental Sciences 2018年第6期30卷 151-159页

作者： nelson j.o’driscoll Emma Vost Erin Mann Sara Klapstein Robert Tordon Matthew Lukeman Department of Earth & Environmental Science Acadia University Wolfville B4P 2R6 Nova Scotia Canada Environment Canada Dartmouth Nova Scotia Canada Department of Chemistry Acadia University Wolfville B4P 2R6 Nova Scotia Canada

Mercury is a globally distributed, environmental contaminant. Quantifying the retention and loss of mercury is integral for predicting mercury-sensitive ecosystems. There is little information on how dissolved organic carbon（DoC） concentrations and particulates affect mercury photoreaction kinetics in freshwater lakes. To address this knowledge gap,samples were collected from ten lakes in Kejimkujik National Park, Nova Scotia（DoC： 2.6–15.4 mg/L）. Filtered（0.2 μm） and unfiltered samples were analysed for gross photoreduction, gross photooxidation, and net reduction rates of mercury using pseudo first-order curves. Unfiltered samples had higher concentrations（p = 0.04） of photoreducible divalent mercury（Hg（II）RED）（mean of 754 ± 253 pg/L） than filtered samples（mean of 482 ± 206 pg/L）;however, gross photoreduction and photooxidation rate constants were not significantly different in filtered or unfiltered samples in early summer. DoC was not significantly related to gross photoreduction rate constants in filtered（R2= 0.43; p = 0.08） and unfiltered（R2= 0.02; p = 0.71） samples; DoC was also not significantly related to gross photooxidation rate constants in filtered or unfiltered samples. However, DoC was significantly negatively related with Hg（Ⅱ）RED in unfiltered（R2= 0.53; p = 0.04）, but not in filtered samples（R2= 0.04;p = 0.60）. These trends indicate that DoC is a factor in determining dissolved mercury photoreduction rates and particles partially control available Hg（Ⅱ）RED in lake water. This research also demonstrates that within these lakes gross photoreduction and photooxidation processes are close to being in balance. Changes to catchment inputs of particulate matter and DoC may alter mercury retention in these lakes and could partially explain observed increases of mercury accumulation in biota.

关键词： Mercury Photoreduction Photooxidation Dissolved organic carbon(DoC) Particulates Kejimkujik National Park

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Mercury bioaccumulation in aquatic biota along a salinity gradient in the Saint john River estuary

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journal of Environmental Sciences 2018年第6期30卷 41-54页

作者： Bethany L.Reinhart Karen A.Kidd R.Allen Curry nelson j.o’driscoll Scott A.Pavey Department of Biology and Canadian Rivers Institute University of New Brunswick Saint John Saint John New Brunswick E2L4L5 Canada Department of Biology Forestry and Environmental Management and Canadian Rivers Institute University of New Brunswick Fredericton New Brunswick E3B4A3 Canada Department of Earth and Environmental Sciences Acadia University Wolfville Nova Scotia B4P2R6 Canada Department of Biology and School of Geography & Earth Sciences McMaster University Hamilton Ontario LSS 4K1 Canada

Although estuaries are critical habitats for many aquatic species, the spatial trends of toxic methylmercury（MeHg） in biota from fresh to marine waters are poorly understood. our objective was to determine if MeHg concentrations in biota changed along a salinity gradient in an estuary. Fourspine Stickleback（Apeltes quadracus）, invertebrates（snails,amphipods, and chironomids）, sediments, and water were collected from ten sites along the Saint john River estuary, New Brunswick, Canada in 2015 and 2016, with salinities ranging from 0.06 to 6.96. Total mercury（proxy for MeHg） was measured in whole fish and MeHg was measured in a subset of fish, pooled invertebrates, sediments, and water. Stable sulfur（δ34S）, carbon（δ13 C）, and nitrogen（δ15N） isotope values were measured to assess energy sources（S, C） and relative trophic level（N）. There were increases in biotic δ13C and δ34S from fresh to more saline sites and these measures were correlated with *** aqueous MeHg was higher at the freshwater than more saline sites, only chironomid MeHg increased significantly with salinity. In the Saint john River estuary, there was little evidence that MeHg and its associated risks increased along a salinity gradient.

关键词： Stickleback Amphipod Methylmercury Biomagnification Stable isotopes Food web

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jES Special issue in Mercury Biogeochemistry and Fate

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journal of Environmental Sciences 2018年第6期30卷 1-4页

作者： Tom Sizmur nelson o'driscoll Yong Cai

The global and regional redistribution of mercury within the environment is of primary importance to both natural ecosystems and human *** ratification of the Minamata Convention on Mercury by 91 parties represents a ... 详细信息

关键词： jES Special issue in Mercury Biogeochemistry and Fate Hg

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Corrigendum to Mercury photoreduction and photooxidation in lakes:effects of filtration and dissolved organic carbon *** of Environmental Sciences 68(2018)151-159

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journal of Environmental Sciences 2021年第5期33卷 347-350页

作者： nelson j.o'Driscol Emma Vost Erin Mann Sara Klapstein Robert Tordon Matthew Lukeman Department o f Earth&Environmental Science.Acadia University WolfuilleNova ScotiaCanada B4P 2R62 Environment Canada DartmouthNova Scotia Department of Chemistry Acadia UniversityWolfuilleNova ScotiaCanada B4P 2R6

"Filtered(0.2μm)and unfiltered samples were analyzed for gross photoreduction,gross photooxidation,and net reduction rates of mercury using pseudo first-order curves.

关键词： lakes Mercury dissolved

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Crystalline compounds for remediation of rare-earth fission products:A review

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journal of Rare Earths 2022年第3期40卷 365-380,I0001页

作者： Saehwa Chong Brian j.Riley Zayne j.nelson Pacific Northwest National Laboratory RichlandWA99352USA

Rare earth(RE)-containing crystals have been investigated as media for the immobilization of RE fission products from nuclear waste *** reprocessing of spent nuclear fuel,fission products including REs,alkalis,and alkaline earths released from the *** viable option to immobilize the RE fission products is to incorporate them into chemically durable crystalline phases in specific waste *** study summarizes the crystal structures and synthesis methods of six RE-containing compounds that have applications in remediation of RE fission *** compounds include oxyapatite(AE_(2)RE_(8)(Sio_(4))_(6)o_(2)),oxychloride(REoCl),borosilicate(RE_(3)BSi_(2)o_(10)),pyrochlore(RE_(2)M_(2)o_(7)),monazite(REPo_(4)),and perovskite(REMo_(3))where AE denotes alkaline earth metals and M denotes transition *** review provides an overview of literature on the usage of these six compounds for immobilizing RE fission products and summarizes different synthesis methods for producing these *** of structural parameters with different REs in each compound are also discussed.

关键词： Rare-earth compounds Nuclear waste forms Crystal structures Synthesis of rare-earth compounds

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Animal behavior can inform conservation policy, we just need to get on with the jobor can it？

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Current Zoology 2014年第4期60卷 479-485页

作者： Ximena j. nelson, Editor School of Biological Sciences University of Canterbury Private Bag 4800 Christchurch New Zealand

1 Conservation Behavior as an Emerging Discipline on the Brink of Success, or Unrealistic Ideal？ It seems intuitively sensible that an understanding of the behavioral characteristics of animals, such as their home ranges, diets, mating systems, and dispersal me- chanisms, may be useful to inform conservation efforts in determining, for example, suitable reintroduction areas, or the design of dispersal corridors.

关键词：行为特征动物减排新兴学科活动范围交配系统疏散通道再引入

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Magnetic Helical Micro-and Nanorobots:Toward Their Biomedical Applications

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Engineering 2015年第1期1卷 21-26页

作者： Famin Qiu Bradley j.nelson Institute of Robotics and Intelligent Systems(IRIS) ETH Zurich

Magnetic helical micro- and nanorobots can perform 3D navigation in various liquids with a sub- micrometer precision under low-strength rotating magnetic fields （〈 10 rer）. Since magnetic fields with low strengths are harmless to cells and tissues, magnetic helical micro/ nanorobots are promising tools for biomedical applications, such as minimally invasive surgery, cell manipulation and analysis, and targeted therapy. This review provides general information on magnetic helical micro/nanorobots, including their fabrication, motion control, and further functionalization for biomedical applications.

关键词： magnetic helical micro/nanorobots mobilemicro/nanorobots artificial bacterial flagella (ABFs) functionalization biomedical applications

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Distance assessment of detours by jum ping spiders

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Current Zoology 2020年第3期66卷 263-273页

作者： Samuel AGUILAR-ARGUELLo Daniel GERHARD Ximena j.nelson School of Biological Sciences University of CanterburyPrivate Bag 4800Christchurch 8140New Zealand School of Mathem atics and Statistics University of CanterburyPrivate Bag 4800Christchurch 8140New Zealand

To take an indirect route(detour)in order to reach a specific target requires complex cognitive *** more demanding,from the cognitive point of view,is when the goal is only visible at the beginning of the *** spiders from the family Sa lticidae,vision is a key sensory modal-ity mediating navigation and prey *** acute vision allows them to perform complicated detours,possibly as a consequence of the multitude of potential routes in their typically complex 3-dimensional *** used a 4-route choice test,in which routes differed in being either short or long and in the presence or absence of a lure of a prey item,to investigate route assessment in 2 salticid species,Trite planiceps and Marpissa *** both species showed evidence of motivation to follow lured-routes,judging by the number of times they re-oriented toward them while detouring,we found that Trite chose short routes in preference to long routes,but did not prefer the *** contrast,Marpissa exhibited random route choice,although it ori-ented toward lured-routes more often than control routes(lure absent).our results suggest that decision-making processes about which route to take occurs before embarking on a route,but this is cognitively *** exhibited cognitive limitations in which the lack of visibility of the goal affected ***,the severity of cognitive limitations depended on *** suggest that variability in spatial ability across the Salticidae may be related to the habitat complexity inhabited by each species.

关键词： cognition cognitive limitations decision-making detour behavior Salticidae spatial task

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Statistical distribution of geomechanical properties and‘Sweet Spots’identification in part of the upper Bakken

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Petroleum Research 2023年第3期8卷 301-308页

作者： nelson R.K.Tatsipie james j.Sheng Texas Tech University United States

Completions and Reservoir Quality are two key attributes that are used to characterize nonconventional hydrocarbon *** is because,for optimum exploitation of these unconventional assets,horizontal wells need to be drilled in“Sweet Spots”(i.e.,regions where Completions and Reservoir Quality are both superior).one way to quantify these qualities is to use reservoir and geomechanical *** properties can be estimated on a location basis from well logs,and then mapped over terrain using geostatistical *** study presents a‘Sweet Spots’identification workflow based on three performance indexes(Storage Potential Index,Brittleness Index,and Horizontal Stress Index)that can be used to quantify CQ and *** performance indexes are computed from petrophysical property volumes(of Young's Modulus,Bulk Modulus,Shear Modulus,Poisson's Ratio,Minimum Horizontal Stress,Volume of Shale,Total organic Carbon,Thickness,and Porosity)which are in turn computed from well logs and geostatistical *** the end,the study offers a method to compare the predicted“Sweet Spots”against available production data via their correlation *** resulting reasonable formation property maps,the successful identification of‘Sweet Spots’,and a correlation coefficient of 0.88(between the predicted“Sweet Spots”and well production data)point to the potential of the proposed effort.

关键词： Sweet spots Sequential Gaussian simulation Storage potential index Brittleness index Horizontal stress index

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