Acidification and metal contamination in Whitepine Lake (Sudbury,Canada): a paleolimnological perspective     

Aruna S. Dixit  Sushil S. Dixit  John P. Smol 《Journal of Paleolimnology》1993,9(2):141-146

Diatom and chrysophyte assemblages from a sediment core from Whitepine Lake were examined to infer changes in lakewater pH, nickel and aluminum concentrations since pre-industrial times, and to help determine the cause of the virtual extirpation of the lake trout population from the lake during the 1960s and 1970s. Our study indicates that acidification started in the 1920s, and that the maximum inferred pH decline (from 6.2 to 5.8) occurred between 1960 and 1970, coincident with the peak in metal mining and smelting activity in the Sudbury basin. Lakewater [Al] and [Ni], as inferred from our diatom transfer functions, increased. It appears that in addition to the pH decline, elevated [Al] may have played an important role in the decline of lake trout from Whitepine Lake in the 1960s and 1970s. Diatom-inferred lakewater pH and [Ni] have recovered slightly in the recent sediments, which coincides with reductions in emissions that have occurred since the mid-1970s.  相似文献   

青海拉脊山东段水系沉积物地球化学异常特征     

罗开欢 《矿产与地质》1993,7(4):307-310

青海拉脊山东段水系沉积物地球化学测量,发现金源、喇嘛庙、七里寺峡Au、As、Ag、Bi、Sb、Hg等元素的水系沉积物组合异常.Au、Ag、As相对高浓度带发育形态、分布范围、异常浓集中心吻合,与区内已知尼旦沟金矿床地球化学异常特征可以类比,发现有金、铜矿体和金矿化,显示铜金成矿的有望远景地段.  相似文献   

5-Br-PADAP-TritonX-100析相光度多波长K系数法测定微量铁、钴、镍、铜     

周发连  高艳明  邹晓红 《华东地质学院学报》1992,(2)

本文研究了Fe(Ⅲ),Co(Ⅱ),Ni(Ⅱ.),Cu(Ⅱ)在5-Br-PADAP-TritonX-100体系中的析相显色反应。利用该体系具有一定选择性和富集、分离的特点,采用多波长K系数法,根据公式ΔA=A-sum from i=1 to n K_iA_i=KC,在一个测定波长和与干扰组分个数相等的参比波长下,测定混合多组分体系的吸光度。求得相应K值后,再计算各待测组分含量。本法用于测定人发中微量铁、钴、镍、铜取得了满意结果。  相似文献   

Polarographische Bestimmung von Nickel und Chrom in Klärschlämmen Polarographic Determination of Nickel and Chromium in Sewage Sludge     

M. Kolb  J. Mann  J. Schfer  F. Müller  G. Bogenschütz  C. Dengler 《洁净——土壤、空气、水》1994,22(6):261-264

The contents of Ni and Cr in sewage sludge with high and low amounts of heavy metals were investigated by polarography. The DIN-digestion (aqua regia) was used, and the resulting solution was treated with H₂O₂/UV (90 °C, 60 min) for further destroying of the organic material. Besides, the solution of the DIN-digestion was examined with AAS (flame) and ICP-OES. With the determination of Ni it was shown that after digestion with aqua regia no further treatment with H₂O₂/UV is necessary. Contrariwise it was found that for the determination of Cr a H₂O₂/UV photolysis is necessary followed by further steps to get good agreement with AAS and ICP results as well as with the certified values of a sludge of the Community Bureau of Standards.  相似文献   

内蒙白乃庙斑岩铜钼矿床黄铁矿中微量元素的分配特征及其意义     

陈德兴 《地球科学》1987,(6)

黄铁矿是一种分布广泛的硫化物,但不同条件下形成的黄铁矿中微量元素的分配各具特点。本文通过对黄铁矿空间分布特征及其中多种微量元素分配特点的研究,提出黄铁矿晕的概念,讨论了其地质意义,对南北两矿带成因的同一性提供了新的信息,并提出矿体不同部位黄铁矿中Co/Ni比值的差异规律可作为判断矿体剥蚀深度的标志。  相似文献   

Origin of Dissolved Groundwater Sulphate in Coastal Plain Sediments of the Rio de la Plata, Eastern Argentina     

Williams S. Logan  Ronald V. Nicholson 《Aquatic Geochemistry》1997,3(4):305-328

Groundwater of the coastal plain of the Rio de La Plata, Argentina,contains up to 17 g L^-1 SO₄ and 37 gL^-1 TDS. Some of this SO₄ is from paleo-seawater intrusion; however, SO₄ : Cl ratios can be>2 : 1, and most of the SO₄ must, therefore, have another source. Three possible sources were investigated: gypsum, organic matter,and iron sulphides. Dissolved SO₄ showed δ³⁴S valuesfrom -7 to 0‰, typical values for S from iron sulphides or organicmatter, but distinct from that of seawater (+22‰). To test whetherthe SO₄ was derived from oxidation of reduced S, four 4-mcores were taken from marine sediments of the coastal plain. Two were takenfrom higher, drier areas where the highest dissolved SO₄values were encountered, and two were taken from lower, wetter areas thathad much lower SO₄ concentrations. Pore waterSO₄, Cl and alkalinity were determined; solids were analyzedfor SO₄, sulphide-S and organic-S. Sulphide-S was the dominant form of reduced S, averaging about0.5% S in the lower interval (2.5–4 m) of the cores. Sulphidewas absent in the upper 2.5 m in both topographically higher and lowerareas. Sulphate was present in the entire unit in the higher, drier areas,but almost absent in lower areas. Organic-S was insignificant. Our model for the origin of dissolved SO₄ is: fine-grainedpyrite was oxidized during hotter or drier periods. Some resulting dissolvedSO₄ was precipitated as gypsum. Iron from the pyriteprecipitated as FeOOH. Lower, wetter areas formed over time where recharginggroundwater dissolved most of the gypsum. In higher areas with low hydraulicgradients and high net evapotranspiration, SO₄ remained asgypsum and in the dissolved phase. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Understanding the Development of the 2018/19 Central Pacific El Ni?o     

Chengyang GUAN  Xin WANG  Haijun YANG 《大气科学进展》2023,40(1):177-185

A central Pacific(CP) El Ni?o event occurred in 2018/19. Previous studies have shown that different mechanisms are responsible for different subtypes of CP El Ni?o events(CP-I El Ni?o and CP-II El Ni?o). By comparing the evolutions of surface winds, ocean temperatures, and heat budgets of the CP-I El Ni?o, CP-II El Ni?o, and 2018/19 El Ni?o, it is illustrated that the subtropical westerly anomalies in the North Pacific, which led to anomalous convergence of Ekman flow and surface warming in the ...  相似文献   

Seasonal Prediction of the Record-Breaking Northward Shift of the Western Pacific Subtropical High in July 2021     

Shuai HU  Tianjun ZHOU  Bo WU  Xiaolong CHEN 《大气科学进展》2023,40(3):410-427

The unprecedented Zhengzhou heavy rainfall in July 2021 occurred under the background of a northward shift of the western Pacific subtropical high(WPSH). Although the occurrence of this extreme event could not be captured by seasonal predictions, a skillful prediction of the WPSH variation might have warned us of the increased probability of extreme weather events in Central and Northern China. However, the mechanism for the WPSH variation in July2021 and its seasonal predictability are still un...  相似文献   

Partitioning of Ni between olivine and siliceous eclogite partial melt: experimental constraints on the mantle source of Hawaiian basalts   总被引：1，自引：0，他引：1  

Zhengrong Wang  Glenn A. Gaetani 《Contributions to Mineralogy and Petrology》2008,156(5):661-678

Olivine is abundant in Earth’s upper mantle and ubiquitous in basaltic lavas, but rarely occurs in eclogite. Partial melts of eclogite are, therefore, not in equilibrium with olivine, and will react with peridotite as they migrate through the upper mantle. If such melts erupt at Earth’s surface, their compositions will be highly modified and they may be olivine-saturated. We investigated experimentally the reaction between olivine and siliceous eclogite partial melt, and determined element partitioning between olivine and the melt produced by this reaction. Our results demonstrate that mixing of reacted eclogite partial melt with primitive basalt is capable of producing the positive correlation between melt SiO₂ content and olivine Ni content observed in some Hawaiian lavas. Experiments were carried out by equilibrating eclogite partial melt or basalt with San Carlos olivine at 1 bar and 1,201–1,350°C. Our results show that eclogite partial melts equilibrated with mantle olivine retain their high SiO₂, low FeO and MgO characteristics. Further, olivine-melt partition coefficients for Ni measured in these experiments are significantly larger than for basalt. Mixing of these melts with primitive Hawaiian tholeiitic lavas results in crystallization of high-Ni olivines similar to those in Makapuu-stage Koolau lavas, even though the mixed magmas have only moderate Ni contents. This results from a hyperbolic increase of the Ni partition coefficient with increasing polymerization of the mixed melt. Note that while eclogite partial melt in contact with peridotite will equilibrate with pyroxene as well as olivine, this will have the effect of buffering the activity of SiO₂ in the reacted melt at a higher level. Therefore, an eclogite partial melt equilibrated with harzburgite will have higher SiO₂ than one equilibrated with dunite, enhancing the effects observed in our experiments. Our results demonstrate that an olivine-free “hybrid” pyroxenite source is not required to explain the presence of high-Ni olivines in Hawaiian lavas and, therefore, indicate that the proportion of eclogite in the Hawaiian plume is less than has been estimated in recent studies.  相似文献   

Nickel enrichment in mantle olivine beneath a volcanic front   总被引：4，自引：1，他引：3  

Satoko Ishimaru  Shoji Arai 《Contributions to Mineralogy and Petrology》2008,156(1):119-131

We found abnormally Ni-rich olivine (Fo = 93) with up to 5.3 wt% of NiO, ten times higher than the ordinary mantle value (0.4 wt%), in a highly metasomatized mantle peridotite xenolith from Avacha volcano, the Kamchatka arc, Russia. The Ni enrichment displays outward diffuse circular domains (<1 mm across) in fine-grained (mostly <100 μm) olivine-rich parts. Associated metasomatic orthopyroxene also shows high NiO (<1.1 wt%). Such high Ni concentrations in olivine cannot be attained in ordinary residual or cumulus peridotites, but are achievable via diffusion from Ni-rich sulfide melt. Sulfur-bearing silicic melt, the main metasomatic agent for the Avacha peridotites, separated sulfide melt, which was fractionated to be Ni-rich at relatively low temperatures. This is a new way of mobility and redistribution of Ni in the mantle, which is active in the mantle wedge, especially beneath a volcanic front.  相似文献