Paleolimnological reconstructions of Rouyn-Noranda lakes within the zone of influence of the Horne Smelter,Québec,Canada

Diatoms were identified and enumerated from a surface sediment calibration set of 50 lakes in northwestern Québec. The relationship between species composition and environmental variables was examined using canonical correspondence analysis (CCA). Forward selection and Monte Carlo permutation tests in CCA indicated that diatom species distributions in the data set are most strongly correlated to lakewater pH. A strong (r ² _boot = 0.83) weighted averaging calibration model, that includes bootstrapped error estimates, was developed for inferring past lakewater pH. Using this model, temporal changes in pH were reconstructed for two kettle lakes, Lac de la Pépinière and Lac Perron. Based on limnological data, both the study lakes were expected to have recently acidified due to increased acidic precipitation and increases in anthropogenic metal loading. However, our long-term pH inference data indicate that these lakes were naturally acidic during pre-industrial times. Nonetheless, the rate of acidification, particularly in Lac de la Pépinière, has accelerated in the last ∼75 years. These long-term pH records developed for the dilute lakes in northwestern Québec suggest that the region has received increased atmospheric pollutants from the nearby Horne smelter in Rouyn-Noranda. The pH inference profiles are markedly different from many other paleolimnological studies in acid-sensitive regions of Canada that have become acidic primarily as a result of industrial activities. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users.     

Nickel isotope fractionation during laterite Ni ore smelting and refining: Implications for tracing the sources of Ni in smelter-affected soils

Nickel isotope ratios were measured in ores, fly ash, slags and FeNi samples from two metallurgical plants located in the Goiás State, Brazil (Barro Alto, Niquelândia). This allowed investigating the mass-dependent fractionation of Ni isotopes during the Ni-laterite ore smelting and refining. Feeding material exhibits a large range of δ⁶⁰Ni values (from 0.02 ± 0.10‰ to 0.20 ± 0.05‰, n = 7), explained by the diversity of Ni-bearing phases, and the average of δ⁶⁰Ni_{feeding materials} was found equal to 0.08 ± 0.08‰ (2SD, n = 7). Both δ⁶⁰Ni values of fly ash (δ⁶⁰Ni = 0.07 ± 0.07‰, n = 10) and final FeNi produced (0.05 ± 0.02‰, n = 2) were not significantly different from the feeding materials ones. These values are consistent with the very high production yield of the factories. However, smelting slags present the heaviest δ⁶⁰Ni values of all the smelter samples, with δ⁶⁰Ni ranging from 0.11 ± 0.05‰ to 0.27 ± 0.05‰ (n = 8). Soils were also collected near and far from the Niquelândia metallurgical plant, to evaluate the potential of Ni isotopes for tracing the natural vs anthropogenic Ni in soils. The Ni isotopic composition of the non-impacted topsoils developed on ultramafic rocks ranges from −0.26 ± 0.09‰ to −0.04 ± 0.05‰ (n = 20). On the contrary, the Ni isotopic composition of the non-ultramafic topsoils, collected close to the plant, exhibit a large variation of δ⁶⁰Ni, ranging from −0.19 ± 0.13‰ up to 0.10 ± 0.05‰ (n = 4). This slight but significant enrichment in heavy isotopes highlights the potential impact of smelting activity in the surrounding area, as well as the potential of Ni isotopes for discerning anthropogenic samples (heavier δ⁶⁰Ni values) from natural ones (lighter δ⁶⁰Ni values). However, given the global range of published δ⁶⁰Ni values (from −1.03 to 2.5‰) and more particularly those associated to natural weathering of ultramafic rocks (from −0.61 to 0.32‰), the use of Ni isotopes for tracing environmental contamination from smelters will remain challenging.     

文山铝土矿A12O3测试中半二甲酚橙的作用

一水硬铝石及含刚玉（A12O3）铝土矿的测试较困难。NaF置换滴定法以二甲酚橙及半二甲酚橙较敏锐。可用半二甲酚橙（变色酸度在PH=5～6）直接调节酸度,再用作滴定的指示剂,效果较好。     

Geochemical investigations of slags from the historical smelting in Freiberg, Erzgebirge (Germany)

The Freiberg area in the Saxon Erzgebirge (Ore Mountains) represents one of the oldest mining districts in Germany. Argentiferous ore mineralizations with lead, zinc and copper are dominating in this region. Various waste products of mining can be found around Freiberg. In particular, the slags from ore smelting were and are regarded as unusable waste products. However, they preserve information on the smelting and weathering behaviour of slag, which makes them very useful sources of information for our purposes. To reconstruct the chemical processes during ore smelting, historical slag represents a most valuable archive. Therefore, the historical slag dump in Halsbach (Germany) was examined exemplarily for the Freiberg deposit. The slag was dumped approx. 400 years ago and is rich in lead. An interrelation between the slag and the metallurgical process applied can be made on the basis of chemical composition, appearance and microscopic results. The slags of the heap in Halsbach contain high concentrations of heavy metals (average contents in mg kg⁻¹: Zn 40,000; Pb 10,000; Cu 1500; U 1000). Enrichments of heavy metals in the organic-rich soil horizons within the range of the dump foot (maximum contents in the A-horizon in mg kg⁻¹: Zn 3719; Pb 9198; As 3017; Cu 963) imply a faint discharge of metals from the dump.     

铜锌冶炼废水中砷含量的分析方法

采用国标方法DDTC-Ag分光光度法测定铜锌冶炼废水中砷的含量,通过改变酸度、锌粒重量和比色皿厚度等条件,最终确定试验最佳参数为硫酸(1+1) 4ml、10目～20目的无砷锌粒和20mm比色皿,据此,该方法能提高铜锌冶炼废水中砷含量分析的准确度.