Low-temperature bonding of Si wafers has been studied utilizing reactive ion etching-mode plasma activation. The hydrophilic Si and thermally oxidized Si wafers were exposed to N 2 , Ar, or O 2 plasma prior to bonding in air or vacuum. After plasma treatment the wafers were cleaned in RCA-1 solution and/or deionized water. Strong bonding was achieved at 200°C with all the investigated plasma gases, if proper bonding and cleaning procedures were used. Extended RCA-1 cleaning deteriorated the bond strength, but a short cleaning improved bonding. We found that the activation of the thermal oxide has a larger influence on the bond strength than the activation of the native oxide surface in Si/oxide wafer pairs. We suggest that the plasma treatment induces a highly disordered surface structure, which enhances the diffusion of the water from the bonded interface. As a result of the plasma exposure the number of the surface OH groups is greatly increased enabling strong bonding at a low temperature.

: Relationship between mineralogy and the physico-chemical properties of till in central Finland. Bull. Geo!. Soc. Finland 64, Part 1,.The chemical and physical characteristics of the fine fraction of till were examined in the area of the Raahe-Ladoga metallogenic belt in central Finland. Till, weathered bedrock and rock samples were collected from the area, where element concentrations of till abruptly ranged from high in an anomalous zone (NE) to low in a non-anomalous zone (SW). The grain size distribution, specific surface area and unit weight, and the leachability of elements measured with several chemical methods were determined from the fine fraction (<0.06 mm) of till. The mineralogical composition of the fine fraction of till and weathered bedrock was established with the X-ray diffraction method (XRD), and the chemical composition of rock samples with the X-ray fluorescence method (XRF).The main factor affecting the increased element concentrations in the anomalous zone is the variation in mica and clay mineral types. The abundance of trioctahedral micas (biotite) and vermiculitic clays carrying most of the trace metals dissolved in aqua regia, has affected to the geochemical pattern of till in the study area. The concentrations of trace metals in the iron precipitates extracted with acid oxalate were too low to be used as evidence of the hydromorphic origin of the anomalous zone. The abundance of main silicates (quartz, feldspars) does not vary much in the fine fraction of till throughout the study area.The absence of the swelling smectite component from the surface layers of till indicates that the source was not the underlying weathered bedrock. The till with a vermiculitic mixed-layer mineral in the anomalous zone contains more material from old sediments weathered during interstadial or interglacial time than does the till with a low clay content in the non-anomalous zone. The abrupt change in the mineralogical and physical properties of till in the study area is suggested to be attributed to the difference in the transport and accumulation dynamics of overburden during deglaciation.

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The mining industry is a common source of environmental metal emissions, which cause long-lasting effects in aquatic ecosystems. Metal risk assessment is challenging due to variations in metal distribution, speciation, and bioavailability. Therefore, seasonal effects must be better understood, especially in boreal regions in which seasonal changes are large. We sampled 4 Finnish lakes and sediments affected by mining for metals and geochemical characteristics in autumn and late winter, to evaluate seasonal changes in metal behavior, the importance of seasonality in risk assessment, and the sensitivity and suitability of different risk assessment methods. We compared metal concentrations in sediment, overlying water, and porewater against environmental quality guidelines (EQGs). We also evaluated the toxicity of metal mixtures using simultaneously extracted metals and an acid volatile sulfides (SEM-AVS) approach together with water quality criteria (US Environmental Protection Agency equilibrium partitioning benchmarks). Finally, site-specific risks for 3 metals (Cu, Ni, Zn) were assessed using 2 biotic ligand models (BLMs). The metal concentrations in the impacted lakes were elevated. During winter stratification, the hypolimnetic O2 saturation levels were low (<6%) and the pH was acidic (3.5-6.5); however, abundant O2 (>89%) and neutral pH (6.1-7.5) were found after the autumnal water overturn. Guidelines were the most conservative benchmark for showing an increased risk of toxicity in the all of the lakes. The situation remained stable between seasons. On the other hand, SEM-AVS, equilibrium partition sediment benchmarks (ESBs), and BLMs provided a clearer distinction between lakes and revealed a seasonal variation in risk among some of the lakes, which evidenced a higher risk during late winter. If a sediment risk assessment is based on the situation in the autumn, the overall risk may be underestimated. It is advisable to carry out sampling and risk assessment during periods in which metals are assumed to be the most environmentally harmful. Integr Environ Assess Manag 2016;12:759-771. © 2015 SETAC.

Metal(loid) contamination in sediments is a widespread environmental issue. Sediments act normally as metal(loid) sinks, but if chemical conditions (such as pH or redox potential) change, they can become sources of secondary pollution. Consequently, various strategies for both in and ex situ remediation of contaminated sediments have been developed. One promising method is active capping, which involves the injection of adsorbents as a layer on the sediment surface or the mixing of adsorbents within the sediment. Adsorbents decrease the bioavailability of metal(loid)s.In the present work, the suitability of alkali-activated blast-furnace-slag, metakaolin geopolymer, and exfoliated vermiculite were evaluated for in situ stabilization of two metal(loid)-contaminated lake sediments through laboratory-scale experiments. The results indicated that adsorbent 2 amendments had metal(loid)-specific performance: alkali-activated blast-furnace slag was suitable for Al, Cu, Fe, and Ni; metakaolin geopolymer for Cu, Cr (total), and Fe; and vermiculite for Al and Zn. None of the materials could stabilize Ba, Sr, or Ti. Furthermore, the amendments performed differently in two different lake sediments, implying that the effectiveness of the amendments needs to be confirmed on a case-by-case basis.