Paleolimnological evidence of mining and demographic impacts on Lac Dauriat, Schefferville (subarctic Québec, Canada)

Qualitative and quantitative analysis of fossil diatoms and geochemical signals preserved in the sediments of Lac Dauriat (subarctic Quebec) were performed to evaluate the impacts of nearby mining activity and the expansion of the town of Schefferville on the water quality of the lake, and to reconstruct the changes of its trophic status. The presence of taxa typical of nutrient-enriched environments (e.g., Cyclostephanos invisitatus, Nitzschia gracilis, Nitzschia perminuta) and the low percentages of chrysophytes were indicative of the advanced state of eutrophication of the lake during the peak of mining activity, and were evidence of the negative impacts of municipal waste on the water quality of Lac Dauriat. Sedimentary analysis of metals, notably lead, mercury, cadmium, bismuth, cobalt, copper and zinc, showed maximum concentrations between 1940 and 1960 with mining era to pre-development enrichment factors ranging from 4.5 to 7.9. The changes seen in recent sediments reflected 3 distinct stages in the recent history of this ecosystem: (a) the non-perturbed, pre-mining (1882–1939), (b) the perturbed, mining period (1939–1977) with accelerated eutrophication, and (c) the post-mining period (1977–1999) with indications of natural recovery of the system after the installation of a water treatment plant in 1975, the closing of the mine in 1983, and the subsequent exodus of the town’s population. Despite the trajectory towards a return to the lake’s natural conditions, water resource managers and (paleo-)limnologists should be alarmed that the impacts of past human disturbance are still in evidence more than 20 years after the closure of the mines, and that Lac Dauriat has yet to reach its natural state of the period preceding extreme anthropogenic impact.     

Chemical variability in the Sacramento River and in Northern San Francisco Bay

Specific conductance and concentrations of alkalinity, dissolved silica, nitrate, and ammonium were measured daily in the Sacramento River flow to northern San Francisco Bay during the rainfall seasons of 1983 and 1984 (high flow) and during late summer and early fall of 1984 (low flow). Flow and concentrations of chemical species varied in response to storm events during high flow, but flow was more variable than concentrations of chemical species. Runoff from agriculturally developed areas appeared to increase specific conductance and concentrations of alkalinity during high flow. During low flow, inputs of agricultural tailwaters caused variations in concentrations of alkalinity and dissolved silica. Dilution of municipal waste by river flow caused variability in concentrations of ammonium during both high flow and low flow. Distributions of alkalinity, dissolved silica, nitrate, and ammonium were measured in northern San Francisco Bay during late summer and fall of 1984. Changes in distributions of alkalinity in the estuary were caused by variations in alkalinity in the Sacramento River. Changes in distributions of dissolved silica, nitrate, and ammonium appeared to be primarily related to variations in supply by the river and removal by phytoplankton. Effects of removal by phytoplankton were large for ammonium and dissolved silica, but appeared relatively small for nitrate.     

Flood Management Strategy for the Upper and Middle Odra River Basin: Feasibility Study of Raciborz Reservoir

The river Odra, which rises in the Czech Republic and disgorges into the Baltic, suffered an extreme flood in July 1997 which was responsible for the loss of 55 lives and over a billion dollars worth of damage in southern Poland. The return period of the flood is variously estimated between 250 and 1000 years. The paper describes the hydrological and hydraulic studies undertaken for a flood reservoir (storage capacity is approximately 180,000,000 m³) to be constructed on the River Odra just upstream the ancient town of Raciborz, on the border between Poland and Czech Republic. These studies included the hydrodynamic modelling of a 220 km stretch of the river down to the city of Wroclaw where most of the damage occurred, flood damage analysis with and without the proposed reservoir, sensitivity analysis of operating rules for Nysa reservoirs and improvement of flood control capacity of existing channels and polders. Cost-benefits analysis, environmental impact assessments and resettlement plans, in addition to the engineering studies of the dam itself, were also carried out during the project stage but have not been included in the present paper.     

Molecular investigations into pollutant impact on roundnose grenadier (C. rupestris) and transplanted common mussel (M. edulis) in Skagerrak, the North Sea

The use of a suite of different biochemical markers in the deep sea fish Roundnose grenadier and caged common mussels, and analyses of contaminant levels in the mussels, indicate that Skagerrak are more polluted than waters around the Faroe Islands. In Roundnose, induction of ethoxyresorufin-O-deethylase (EROD) is consistent with increased benzo(a)pyrene hydroxylase (BPH) in mussels and elevated levels of polynuclear aromatic hydrocarbons (PAHs) in mussels and sediment from Skagerrak. This evidence of a large-scale environmental impact of pollutants should lead to further efforts to decrease transport into, and deposition of, waste compounds in the Skagerrak area.     

High-resolution parallel electron energy-loss spectroscopy of Mn L2,3-edges in inorganic manganese compounds

Parallel electron energy-loss spectroscopy (PEELS) in a scanning transmission electron microscope (STEM) was used to record the Mn L_2,3-edges from a range of natural and synthetic manganese containing materials, covering valences 0, II, III, IV and VII, with an energy resolution of ca. 0.5 eV. The Mn L_2,3 electron-loss near-edge structure (ELNES) of these edges provided a sensitive fingerprint of its valence. The Mn²⁺ L_2,3-edges show little sensitivity to the local site symmetry of the ligands surrounding the manganese. This is illustrated by comparing the Mn L_2,3-edges from 4-, 6- and 8-fold coordinated Mn²⁺. In contrast, the Mn L₃-edges from Mn³⁺ and Mn⁴⁺ containing minerals exhibited ELNES that are interpreted in terms of a crystal-field splitting of the 3d electrons, governed by the symmetry of the surrounding ligands. The Mn L₃-edges for octahedrally coordinated Mn²⁺, Mn³⁺ and Mn⁴⁺ showed variations in their ELNES that were sensitive to the crystal-field strength. The crystal-field strength (10Dq) was measured from these edges and compared very well with published optically determined values. The magnitude of 10Dq measured from the Mn L₃-edges and their O K-edge prepeaks of the manganese oxides were almost identical. This further confirms that the value of 10Dq measured at the Mn L₃-edge is correct. Selected spectra are compared with theoretical 2p atomic multiplet spectra and the differences and similarities are explained in terms of the covalency and site symmetry of the manganese. The Mn L₃-edges allow the valence of the manganese to be ascertained, even in multivalent state materials, and can also be used to determine 10Dq.     

The paleolimnology of a small waterbody in the Pocono Mountains of Pennsylvania,USA: reconstructing 19th–20th century specific conductivity trends in relation to changing land use

Remains of scaled chrysophytes, magnetic minerals and pollen were used to analyze the recent paleolimnological history of a small lake, Lake Waynewood, in the Pocono Mountains of Pennsylvania. Important shifts in all three variables were observed over the 133 years represented by the core. The most significant changes occurred near the turn of the century when the watershed was heavily logged. Before the logging event, species such asSynura sphagnicola, S. spinosa, Mallomonas galeiformis andM. duerrschmidtiae were co-dominant members of the flora. Subsequent to the deforestation of the watershed other taxa, includingM. crassisquama, M. caudata andS. petersenii, increased in relative importance. Concurrent with changes in the scaled chrysophytes was a six-fold increase in the concentrations of magnetic material, presumably the result of increased erosion caused by the logging. Changes in pollen grains also correlate well with the onset of the deforestation event. The scaled chrysophyte inferred specific conductivity of the lake has more than tripled, with the primary increase occurring concurrent with the commencement of logging and the increase in magnetic mineral material. The effects of other human-related disturbances are also discussed.     

To the market and back: Housing policy and state housing in New Zealand

Housing policy in New Zealand has traditionally been characterised by significant market intervention in support of home ownership and a residual state housing rental sector. Within the context of dramatic social welfare reforms in the 1990s, a set of radical housing reforms was introduced that profoundly transformed the role of the state in the housing system. Key elements of the reforms included the creation of a profit-oriented company to manage state rentals, a move to market rents in the state sector and the introduction of an accommodation supplement. This paper examines the underlying rationale and impacts of the reforms focusing on issues of privatisation, tenant turnover, affordability and tenant protest. Having examined the ongoing problems engendered by these reforms the paper reviews more recent political and legislative reforms that were sought to reassert the state's traditional position within the New Zealand housing market. This revised version was published online in July 2006 with corrections to the Cover Date.     

Privatization of rural industry and de facto urbanization from below in southern Jiangsu, China

At the heart of China’s economic transformation from plan to market is the institutional rearrangement of the ownership of property rights. Privatization of collectively owned township and village enterprises (TVEs) in recent years has significantly changed the rural economy and affected small town development in China. Located mainly in villages and small towns and producing 62% of the total industrial output in Jiangsu in 1994, TVEs played a crucial role in southern Jiangsu (Sunan)’s economic development and urbanization, giving rise to the well-known “Sunan model” of regional development during the 1980s. Since the mid-1990s, ownership transition (zhuanzhi) of the TVEs from collective to private in Sunan has altered the nature of the regional economy and the pattern of small town development. The privatization of TVEs in Sunan has been so pervasive that it can be seen as the “second industrial divide” in the region’s economy. This paper traces the evolution of ownership reform in Sunan’s rural industries leading to the current phase of privatization and analyzes the effects of privatization on de facto urbanization from below in Sunan. Given the importance of privatization, continuous scholarly monitoring of its relationship to regional economic development and urbanization from below is necessary.     

Contact metamorphism/hydrothermal alteration of Tertiary basalts from the Isle of Skye,northwest Scotland

Alkali olivine basalts from Skye were simultaneously contact metamorphosed by Tertiary gabbro and granite intrusions and altered by the hydrothermal convection system that the plutons induced. Four metamorphic zones were mapped around the plutons. Furthest from the intrusions, in the primary olivine zone, metabasalts are composed of combinations of igneous olivine, augite, plagioclase, titaniferous magnetite, ilmenite, zeolites, gyrolite, sulfides, and chlorite-smectite intergrowths. Closer to the plutons, in the smectite zone, saponite and carbonate appear, primary olivine and gyrolite disappear, and zeolites decrease dramatically in abundance. Still closer to the plutons, in the amphibole zone, actinolite, edenite, chlorite, sphene, epidote, andradite, and quartz appear and saponite and chlorite-smectite intergrowths disappear. Along parts of the contact between gabbro and basalt, in the orthopyroxeneolivine zone, orthopyroxene, metamorphic olivine, and biotite appear and amphibole, chlorite, sphene, epidote, andradite, carbonate, and quartz disappear. Whole-rock chemical data indicate only minor change in the major-element chemical composition of the metabasalts during progressive metamorphism/hydrothermal alteration. Two-pyroxene eothermometry and various mineral-fluid equilibria suggest the range of peak temperatures attained in the metamorphic zones: orthopyroxene-olivine zone, 900°1, 030° C; amphibole zone, 400°–900° C; smectite and primary olivine zones, < 400° C. Mineralogical and oxygen isotopic alteration of the metabasalts were closely coupled: Basalts from the primary olivine zone with nearly unaltered igneous mineralogies have normal or near-normal wholerock ¹⁸O>+5 (SMOW); mineralogically more altered basalts from the smectite zone have whole-rock ¹⁸O=+2 to +5; still more mineralogically altered basalts from the amphibole zone (with one exception) have ¹⁸O<+ 2; completely recrystallized hornfelses from the orthopyroxene-olivine zone have ¹⁸O<0. The principal mechanism of isotope exchange between basalt and metamorphic/ hydrothermal fluid probably was heterogeneous mineralfluid reaction.Metabasalts from the orthopyroxene-olivine zone are mineralogically fresh pyroxene hornfelses that record crystallization temperatures > 1,000° C yet have highly altered whole-rock oxygen isotope compositions, ¹⁸O<0%. The hornfelses chemically interacted with metamorphic/hydrothermal fluids either at very high temperatures or while they were heated to > 1,000° C or both. Their mineralogy, however, rules out significant water-rock interaction after they cooled below 900° C. Hydrothermal convection on Skye was a two-stage process: (a) fluid flow through wall rocks initially was pervasive while they are heated; (b) fluid flow after the thermal peak in the wall rocks was sufficiently channelized that rocks such as those in the orthopyroxeneolivine zone were isolated from further fluid-rock interaction during all or almost all of the cooling history of the hydrothermal system.