Analysis of pottery samples from Bourewa, the earliest known Lapita site in Fiji

We have carried out a thorough mineralogical analysis of 16 pottery samples from the Lapita site of Bourwera in Fiji, using micromorphological techniques with optical and polarising microscopes. While the overall mineralogy of all of the samples is similar the samples clearly divide into two groups, namely those with or without the mineral calcite. Our findings are backed up by chemical analysis using SEM–EDX and FTIR. SEM–EDX shows the clear presence of inclusions of calcite in some of the samples; FTIR shows bands arising from calcite in these samples. The study suggests that it is likely that more than one clay source was used for production of this pottery, but that most of the pottery comes from a single source. This finding is in line with previous studies which suggest some trading of pottery between the Fijian islands but a single source of clay for most of the pottery found at Bouwera. We found no evidence for the destruction of CaCO3 by heating upon production of the pottery in line with the known technology of the Lapita people who produced earthenware pottery but not high temperature ceramics.

Investigations into the PCDD contamination of topsoil, river sediments and kaolinite clay in Queensland, Australia

Recent findings of elevated PCDDs from an unknown source in the coastal marine environment of Queensland, Australia has instigated further investigations into the distribution of, and environments associated with the PCDD contamination. This study presents data for OCDD concentrations in the coastal, mountainous and inland environment of Queensland. Additionally, full 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and dibenzofuran (PCDD/F) profiles from different land-use types and environments in the coastal region were analysed. Distinct east-west gradients were detected in topsoil collected from various bushland regions with elevated OCDD concentrations confined to the coastal region. However, PCDD/F results from topsoil and river sediments collected in the Queensland coastal region suggest that elevated OCDD concentrations cannot be attributed to any of the environments, land-use or industry types investigated. PCDD/F congener profiles from select samples were remarkably similar to those previously described in marine sediments collected along the entire Queensland coastline. In addition, kaolinite clay samples from Queensland exhibited elevated OCDD concentrations, and PCDD/F profiles in these samples were similar to those detected in kaolinite clays elsewhere. Natural formation processes have been hypothesised as the source of elevated PCDDs in Queensland and other locations, where similar PCDD/F profiles and the general lack of anthropogenic sources are evident. This study presents additional data supporting this hypothesis and provides further information that may assist in the identification of the processes involved in the natural formation of PCDDs. (C) 2002 Elsevier Science Ltd. All rights reserved.

Point source inoculation of Mesocyclops (Copepoda : Cyclopidae) gives widespread control of Ochlerotatus and Aedes (Diptera : Culicidae) immatures in service manholes and pits in North Queensland, Australia

This study details the novel application of predacious copepods, genus Mesocyclops, for control of Ochlerotatus tremulus (Theobald) group and Aedes aegypti (L.) mosquito larvae in subterranean habitats in north Queensland, Australia. During June 1997, 50 Mesocyclops sp. I were inoculated into one service manhole in South Townsville. Wet season rainfall and flooding in both 1998 and 2000 was responsible for the dispersal of copepods via the underground pipe system to 29 of 35 manholes over an area of 1.33 km(2). Significant reductions in Aedes and Ochlerotatus larvae ensued. In these habitats, Mesocyclops and Metacyclops were able to survive dry periods, when substrate moisture content ranged from 13.8 to 79.9%. At the semiarid inland towns of Hughenden and Richmond, cracking clay soil prevents drainage of water from shallow service pits where Oc. tremulus immatures numbered from 292-18,460 per pit. Introduction of Mesocyclops copepods into these sites during May 1999 resulted in 100% control of Oc. tremulus for 18 mo. One uninoculated pit subsequently became positive for Mesocyclops with resultant control of mosquito larvae.

Phosphorus extracted by ion exchange resins and mehlich-1 from oxisols (latosols) treated with different phosphorus rates and sources for varied soil-source contact periods

Despite the large number of studies addressing the quantification of phosphorus (P) availability by different extraction methods, many questions remain unanswered. The aim of this paper was to compare the effectiveness of the extractors Mehlich-1, Anionic Resin (AR) and Mixed Resin (MR), to determine the availability of P under different experimental conditions. The laboratory study was arranged in randomized blocks in a [(3 x 3 x 2) + 3] x 4 factorial design, with four replications, testing the response of three soils with different texture: a very clayey Red Latosol (LV), a sandy clay loam Red Yellow Latosol (LVA), and a sandy loam Yellow Latosol (LA), to three sources (triple superphosphate, reactive phosphate rock from Gafsa-Tunisia; and natural phosphate from Araxá-Minas Gerais) at two P rates (75 and 150 mg dm-3), plus three control treatments (each soil without P application) after four contact periods (15, 30, 60, and 120 days) of the P sources with soil. The soil acidity of LV and LVA was adjusted by raising base saturation to 60 % with the application of CaCO3 and MgCO3 at a 4:1 molar ratio (LA required no correction). These samples were maintained at field moisture capacity for 30 days. After the contact periods, the samples were collected to quantify the available P concentrations by the three extractants. In general, all three indicated that the available P-content in soils was reduced after longer contact periods with the P sources. Of the three sources, this reduction was most pronounced for triple superphosphate, intermediate for reactive phosphate, while Araxá phosphate was least sensitive to the effect of time. It was observed that AR extracted lower P levels from all three soils when the sources were phosphate rocks, while MR extracted values close to Mehlich-1 in LV (clay) and LVA (medium texture) for reactive phosphate. For Araxá phosphate, much higher P values were determined by Mehlich-1 than by the resins, because of the acidity of the extractor. For triple superphosphate, both resins extracted higher P levels than Mehlich-1, due to the consumption of this extractor, particularly when used for LV and LVA.

Properties of debris flow deposits and source materials compared: implications for debris flow characterization

In the Alps, debris flow deposits generally contain < 5% clay-size particles, and the role of the surface-charged < 2 mu m particles is often neglected, although these particles may have a significant impact on the rheological properties of the interstitial fluid. The objective of this study was to compare debris flow deposits and parent materials from two neighbouring catchments of the Swiss Alps, with special emphasis on the colloidal constituents. The catchments are small in area (4 km(2)), 2.5 km long, similar in morphology, but different in geology. The average slopes are 35-40%. The catchments were monitored for debris flow events and mapped for surface aspect and erosion activity. Debris flow deposits and parent materials were sampled, the clay and silt fractions extracted and the bulk density, < 2 mm fraction bulk density, particle size distribution, chemical composition, cation exchange capacity (CEC) and mineralogy analysed. The results show that the deposits are similar to the parent screes in terms of chemical composition, but differ in terms of: (i) particle size distribution; and (ii) mineralogy, reactivity and density of the < 2 mm fraction. In this fraction, compared with the parent materials the deposits show dense materials enriched in coarse monocrystalline particles, of which the smallest and more reactive particles were leached. The results suggest that deposit samples should not be considered as representative of source or flow materials, particularly with respect to their physical properties.

PEASANT AND SCIENTIFIC KNOWLEDGE ON PLANOSOLS AS A SOURCE OF MATERIALS IN THE MAKING OF NON-INDUSTRIAL POTTERY

Ethnopedological studies have mainly focused on agricultural land uses and associated practices. Nevertheless, peasant and indigenous populations use soil and land resources for a number of additional purposes, including pottery. In the present study, we describe and analyze folk knowledge related to the use of soils in non-industrial pottery making by peasant potters, in the municipality of Altinho, Pernambuco State, semiarid region at Brazil. Ethnoscientific techniques were used to record local knowledge, with an emphasis on describing the soil materials recognized by the potters, the properties they used to identify those soil materials, and the criteria employed by them to differentiate and relate such materials. The potters recognized three categories of soil materials: “terra” (earth), “barro” (clay) and, “piçarro” (soft rock). The multi-layered arrangement of these materials within the soil profiles was similar to the arrangement of the soil horizon described by formal pedologists. “Barro vermelho” (red clay) was considered by potters as the principal ceramic resource. The potters followed morphological and utilitarian criteria in distinguishing the different soil materials. Soils from all of these sites were sodium-affected Alfisols and correspond to Typic Albaqualf and Typic Natraqualf in the Soil Taxonomy (Soil Survey Staff, 2010).

Study of stillage biodegradation by respirometry in sandy and clay soils

The stillage, which is a liquid residue from the distillation of the sugarcane ethanolic fermentation, contains organic matter and can be a big source of pollution when it is discarded in the wrong way. Its application as fertilizer has been extended, which is reason to cause concerns regarding the environment. The aim of this work was to evaluate and quantify the biodegradation of stillage in sandy and clay soils, besides verifying the efficiency of the Embiotic Line®inoculum as an accelerator of the biodegradation. Bartha and Pramer respirometric technique was used to determine the production of CO2 during the 50 days of the biodegradation process, and the quantification of the initial and final microorganisms was also conducted. Results were analyzed using the Friedman statistical test. Clay soils were significantly better on stillage decomposition when compared to sandy soils (p=0.0153). Clay soils presented greater efficiency in stillage biodegradation, with higher field capacity, better water, organic matter and microbial retention. Regarding the use of the embiotic line, the experiment has shown this product does not interfere positively in the stillage biodegradation for both soils, possibly needing adjustments in its composition.

Biogeochemical processes in a clay formation in situ experiment: Part F - Reactive transport modelling

Reactive transport modelling was used to simulate solute transport, thermodynamic reactions, ion exchange and biodegradation in the Porewater Chemistry (PC) experiment at the Mont Terri Rock Laboratory. Simulations show that the most important chemical processes controlling the fluid composition within the borehole and the surrounding formation during the experiment are ion exchange, biodegradation and dissolution/precipitation reactions involving pyrite and carbonate minerals. In contrast, thermodynamic mineral dissolution/precipitation reactions involving alumo-silicate minerals have little impact on the fluid composition on the time-scale of the experiment. With the accurate description of the initial chemical condition in the formation in combination with kinetic formulations describing the different stages of bacterial activities, it has been possible to reproduce the evolution of important system parameters, such as the pH, redox potential, total organic C. dissolved inorganic C and SO(4) concentration. Leaching of glycerol from the pH-electrode may be the primary source of organic material that initiated bacterial growth, which caused the chemical perturbation in the borehole. Results from these simulations are consistent with data from the over-coring and demonstrate that the Opalinus Clay has a high buffering capacity in terms of chemical perturbations caused by bacterial activity. This buffering capacity can be attributed to the carbonate system as well as to the reactivity of clay surfaces.

Geochemical and isotopic characterization of the Bodélé Depression dust source and implications for transatlantic dust transport to the Amazon Basin

The Bodélé Depression (Chad) in the central Sahara/Sahel region of Northern Africa is the most important source of mineral dust to the atmosphere globally. The Bodélé Depression is purportedly the largest source of Saharan dust reaching the Amazon Basin by transatlantic transport. Here, we have undertaken a comprehensive study of surface sediments from the Bodélé Depression and dust deposits (Chad, Niger) in order to characterize geochemically and isotopically (Sr, Nd and Pb isotopes) this dust source, and evaluate its importance in present and past African dust records. We similarly analyzed sedimentary deposits from the Amazonian lowlands in order to assess postulated accumulation of African mineral dust in the Amazon Basin, as well as its possible impact in fertilizing the Amazon rainforest. Our results identify distinct sources of different ages and provenance in the Bodélé Depression versus the Amazon Basin, effectively ruling out an origin for the Amazonian deposits, such as the Belterra Clay Layer, by long-term deposition of Bodélé Depression material. Similarly, no evidence for contributions from other potential source areas is provided by existing isotope data (Sr, Nd) on Saharan dusts. Instead, the composition of these Amazonian deposits is entirely consistent with derivation from in-situ weathering and erosion of the Precambrian Amazonian craton, with little, if any, Andean contribution. In the Amazon Basin, the mass accumulation rate of eolian dust is only around one-third of the vertical erosion rate in shield areas, suggesting that Saharan dust is “consumed” by tropical weathering, contributing nutrients and stimulating plant growth, but never accumulates as such in the Amazon Basin. The chemical and isotope compositions found in the Bodélé Depression are varied at the local scale, and have contrasting signatures in the “silica-rich” dry lake-bed sediments and in the “calcium-rich” mixed diatomites and surrounding sand material. This unexpected finding implies that the Bodélé Depression material is not “pre-mixed” at the source to provide a homogeneous source of dust. Rather, different isotope signatures can be emitted depending on subtle vagaries of dust-producing events. Our characterization of the Bodélé Depression components indicate that the Bodélé “calcium-rich” component, identified here, is most likely released via eolian processes of sand grain saltation and abrasion and may be significant in the overall global budget of dusts carried out by the Harmattan low-level jet during the winter.

Resolving Cl and SO4 Profiles in a Clay-Rich Rock Sequence

The chloride and sulfate concentration profiles in a 260 m thick clay-rich Mesozoic sediment sequence have been analyzed by various methods. Chloride data generally indicate a good consistency between different methods if anion exclusion is accounted for in leaching tests. For sulfate, however, there is an apparent inconsistency between leaching data and those obtained from the other methods, which points to the dissolution of a sulfur-bearing mineral. Traces of diagenetic gypsum seem to be a likely source, but other sulfur minerals cannot be ruled out.

Sedimentological and clay mineralogical analysis of ODP sites in the central Fram Strait

This study presents the results of high-resolution sedimentological and clay mineralogical investigations on sediments from ODP Sites 908A and 909AlC located in the central Fram Strait. The objective was to reconstruct the paleoclimate and paleoceanography of the high northern latitudes since the middle Miocene. The sediments are characterised in particular by a distinctive input of ice-rafted material, which most probably occurs since 6 Ma and very likely since 15 Ma. A change in the source area at 1 1.2 Ma is clearly marked by variations within clay mineral composition and increasing accumulation rates. This is interpreted as a result of an increase in water mass exchange through the Fram Strait. A further period of increasing exchange between 4-3 Ma is identified by granulometric investigations and points to a synchronous intensification of deep water production in the North Atlantic during this time interval. A comparison of the components of coarse and clay fraction clearly shows that both are not delivered by the Same transport process. The input of the clay fraction can be related to transport mechanisms through sea ice and glaciers and very likely also through oceanic currents. A reconstruction of source areas for clay minerals is possible only with some restrictions. High smectite contents in middle and late Miocene sediments indicate a background signal produced by soil formation together with sediment input, possibly originating from the Greenland- Scotland Ridge. The applicability of clay mineral distribution as a climate proxy for the high northern latitudes can be confirmed. Based on a comparison of sediments from Site 909C, characterised by the smectite/illite and chlorite ratio, with regional and global climatic records (oxygen isotopes), a middle Miocene cooling phase between 14.8-14.6 Ma can be proposed. A further cooling phase between 10-9 Ma clearly shows similarities in its Progress toward drastic decrease in carbonate sedimentation and preservation in the eastern equatorial Pacific. The modification in sea water and atmosphere chemistry may represent a possible link due to the built-up of equatorial carbonate platforms. Between 4.8-4.6 Ma clay mineral distribution indicates a distinct cooling trend in the Fram Strait region. This is not accompanied by relevant glaciation, which would otherwise be indicated by the coarse fraction. The intensification of glaciation in the northern hemisphere is distinctly documented by a rapid increase of illite and chlorite starting from 3.3 Ma, which corresponds to oxygen isotope data trends from North Atlantic.

Clay mineral assemblages in the western Baltic Sea

Surface samples and nine cores from the western Baltic Sea and marginal water bodies were investigated for clay mineral composition. The clay mineral assemblages of recent sediments are rather homogeneous. Variations result mainly from the erosion of different glacial source deposits. High percentages of illite and low kaolinite/chlorite and quartz/feldspar ratios are characteristic for this glacial source. Advection of kaolinite-rich suspensions from the North Sea is believed to account for higher kaolinite/chlorite ratios in the Mecklenburg Bight. A contribution of the rivers Trave and Oder to the western Baltic Sea is indicated by increased smectite values in marginal water bodies. They correspond to increased kaolinite/chlorite and quartz/feldspar ratios. In the main basins the river signal is diluted beyond recognition. Cores from the Arkona, Bornholm and Gotland Basins penetrate through post-Littorina muds and sediments of the Ancylus Lake/Yoldia Sea into Late Glacial sediments of the Baltic Ice Lake. Clay mineral assemblages are characterized by an increase in kaolinite/chlorite ratios from Late Glacial to Holocene sediments, with a distinct shift at each facies change. This allows the distinction and core to core correlation of main lithological units with kaolinite/chlorite ratios. Kaolinite enrichment of Holocene muds corresponds to a brackish-marine facies and may reflect influx of kaolinite-rich suspensions from the North Sea. Cores from the lagoon of the Oderhaff show fluctuations in the contributions of the two main sediment sources: river suspension and glacial deposits during the Late Glacial and Postglacial sequence. Lacustrine sediments, which were deposited prior to 5500 years B.P. are characterized by smectite, kaolinite and quartz from the drainage area of the Oder river. Erosion of coastal and offshore glacial boulder clays with the Littorina transgression supplied a marine component rich in illite, chlorite and feldspars to the brackish muds of the Oderhaff.

Clay mineralogy and multi-element chemistry of surface sediments on the Aiberian-Arctic Shelf

Clay mineral and bulk chemical (Si, Al, K, Mg, Sr, La, Ce, Nd) analyses of terrigenous surface sediments on the Siberian-Arctic shelf indicate that there are five regions with distinct, or endmember, sedimentary compositions. The formation of these geochemical endmembers is controlled by sediment provenance and grain size sorting. (1) The shale endmember (Al, K and REE rich sediment) is eroded from fine-grained marine sedimentary rocks of the Verkhoyansk Mountains and Kolyma-Omolon superterrain, and discharged to the shelf by the Lena, Yana, Indigirka and Kolyma Rivers. (2) The basalt endmember (Mg rich) originates from NE Siberia's Okhotsk-Chukotsk volcanic belt and Bering Strait inflow, and is prevalent in Chukchi Sea Sediments. Concentrations of the volcanically derived clay mineral smectite are elevated in Chukchi fine-fraction sediments, corroborating the conclusion that Chukchi sediments are volcanic in origin. (3) The mature sandstone endmember (Si rich) is found proximal to Wrangel Island and sections of the Chukchi Sea's Siberian coast and is derived from the sedimentary Chukotka terrain that comprises these landmasses. (4) The immature sandstone endmember (Sr rich) is abundant in the New Siberian Island region and reflects inputs from sedimentary rocks that comprise the islands. (5) The immature sandstone endmember is also prevalent in the western Laptev Sea, where it is eroded from sedimentary deposits blanketing the Siberian platform that are compositionally similar to those on the New Siberian Islands. Western Laptev can be distinguished from New Siberian Island region sediments by their comparatively elevated smectite concentrations and the presence of the basalt endmember, which indicate Siberian platform flood basalts are also a source of western Laptev sediments. In certain locations grain size sorting noticeably affects shelf sediment chemistry. (1) Erosion of fines by currents and sediment ice rafting contributes to the formation of the coarse-grained sandstone endmembers. (2) Bathymetrically controlled grain size sorting, in which fines preferentially accumulate offshore in deeper, less energetic water, helps distribute the fine-grained shale and basalt endmembers. An important implication of these results is that the observed sedimentary geochemical endmembers provide new markers of sediment provenance, which can be used to track sediment transport, ice-rafted debris dispersal or the movement of particle-reactive contaminants.

Clay mineraology and grain size composition of surface sediments from South Pacific Ocean

The reconstruction of low-latitude ocean-atmosphere interactions is one of the major issues of (paleo-)environmental studies. The trade winds, extending over 20° to 30° of latitude in both hemispheres, between the subtropical highs and the intertropical convergence zone, are major components of the atmospheric circulation and little is known about their long-term variability on geological time-scales, in particular in the Pacific sector. We present the modern spatial pattern of eolian-derived marine sediments in the eastern equatorial and subtropical Pacific (10°N to 25°S) as a reference data set for the interpretation of SE Pacific paleo-dust records. The terrigenous silt and clay fractions of 75 surface sediment samples have been investigated for their grain-size distribution and clay-mineral compositions, respectively, to identify their provenances and transport agents. Dust delivered to the southeast Pacific from the semi- to hyper-arid areas of Peru and Chile is rather fine-grained (4-8 µm) due to low-level transport within the southeast trade winds. Nevertheless, wind is the dominant transport agent and eolian material is the dominant terrigenous component west of the Peru-Chile Trench south of ~ 5°S. Grain-size distributions alone are insufficient to identify the eolian signal in marine sediments due to authigenic particle formation on the sub-oceanic ridges and abundant volcanic glass around the Galapagos Islands. Together with the clay-mineral compositions of the clay fraction, we have identified the dust lobe extending from the coasts of Peru and Chile onto Galapagos Rise as well as across the equator into the doldrums. Illite is a very useful parameter to identify source areas of dust in this smectite-dominated study area.