Mineralogical and Geochemical Constraints on the Sediment Sources of Late Stone Age Pottery from the Birimi Site,Northern Ghana

The mineralogy and bulk chemical compositions of 15 Kintampo (Late Stone Age) potsherds from the Birimi site on the Gambaga Escarpment and eight samples of local sediment were determined with the intent of characterizing these wares and identifying the material used in their manufacture. Sediment from clay pits still used by potters north of the escarpment contains iron‐rich laterite clasts (100 × XFeO_t = 100 × FeO_t/[FeO_t + Al₂O₃ + SiO₂] ≥10). Sedimentary clasts in stream sediments are relatively siliceous and iron‐poor (100 × XFeO_t < 10). Bulk geochemical data together with the compositions of lithic clasts (laterite, siltstone/sandstone) link the pottery to sediment sources, including escarpment sediments not presently used by Ghanaian potters. Fresh granite clasts found in some of the sherds were not found in the analyzed sediment samples, although some of their distinctive mineralogical constituents (e.g., variably barian alkali feldspar) are present. The analytical data suggest that pots found at Birimi were made locally by mixing escarpment sediment with clay and stream sediment brought in from below the escarpment. This contrasts with present‐day practice, whereby the pots themselves are imported. The place where Birimi pottery was made and the outcrop source of aluminous sediment (mudstone with an “escarpment” trace element signature) used in these wares, however, remain unidentified. © 2013 Wiley Periodicals, Inc.     

Application of biomarkers for improving risk assessments of chemicals under the Water Framework Directive: a case study

To answer the requirement of the European Commission's Water Framework Directive (WFD) for biological-effects endpoints to classify the ecological health of aquatic ecosystems, we propose the biomarker response index (BRI). The BRI, based on a suite of biomarkers at different levels of biological response at the individual level, provides an integrated relative measure of the general health status of coastal invertebrates. Using the BRI, the health of mussels (Mytilus edulis) from 10 estuaries classified by the Environment Agency of England and Wales under the WFD was compared. Eight sites were healthier than predicted and two showed a similar health status to that of the predicted point-source pollution risk classification. Results indicate that the BRI offers a potential measure of organism health that can be used in monitoring under the WFD as an additional aid to reduce uncertainty in defining risk classification and to provide better evidence of existing impact.     

胶北粉子山群石榴云母片岩的三叠纪独居石年龄及其地质意义

胶北地块粉子山群石榴云母片岩中石榴石变斑晶内包裹物迹线明显,保留了岩石形成过程中的多期变质变形信息。电子探针成分面扫描图显示石榴石成分环带明显,可分为核部、幔部和边部。石榴石中MgO、FeO、MnO和CaO含量变化特征表明其核部到边部温度先升高后降低,对应进变质及退变质过程。根据原位独居石Y元素成分面扫描图显示,部分独居石颗粒由核部到边部Y含量呈现逐渐降低趋势,说明测得的232.6±1.1Ma~229.5±3.7Ma的独居石U-Pb年龄,对应石榴石的进变质生长过程。结合1869±72Ma的锆石U-Pb年龄数据,可推断粉子山群石榴云母片岩至少经历了古元古代及三叠纪两期变质事件的改造。粉子山群石榴云母片岩卷入了苏鲁超高压变质带的俯冲碰撞造山事件。电子探针成分分析结果表明粉子山群石榴云母片岩中的石榴石属于铁铝榴石,反映出经受中级区域变质作用的特征。说明粉子山群石榴云母片岩虽然参与了三叠纪苏鲁超高压变质带的俯冲碰撞造山过程,但俯冲深度较浅。这可用大陆俯冲过程中上盘的俯冲剥蚀来解释,并可为陆-陆碰撞俯冲剥蚀模式提出的扬子板片在240~220Ma的深俯冲作用过程中拽动胶北地块向下俯冲又折返的运动过程提供佐证,但胶北地块是否经历了深俯冲超高压变质作用,还需要进一步验证。     

Erosion response to anthropogenic activity and climatic changes during the Holocene: case studies in northwestern China and southern Norway

Soil erosion assessment and prediction play critical roles in addressing problems associated with erosion control or soil conservation. The past dynamics of soil erosion can provide valuable information for us to understand the relations of soil erosion to environmental change and anthropogenic activity. The present paper has compared Holocene climatic changes in northwestern China with those in southern Norway, and investigated the past dynamics of erosion activity during the Holocene. Modern soil erosion on the Loess Plateau is a combination of the intensive natural erosion and human-induced erosion, the latter being four times greater than the former. Because of global warming and increasing human activities, climate on the Loess Plateau is becoming dryer and more unstable, causing an enhanced erosion problem and water scarcity. In the arctic-alpine region of southern Norway, however, the global warming and regional wetting caused expansion of the largest European ice cap. This has accentuated the erosion in that region, with a higher frequency of avalanches and debris flows.     

Stable carbon and oxygen isotope fractionation in bivalve (Placopecten magellanicus) larval aragonite

The relationship between stable isotope composition (δ¹³C and δ¹⁸O) in seawater and in larval shell aragonite of the sea scallop, Placopecten magellanicus, was investigated in a controlled experiment to determine whether isotopes in larval shell aragonite can be used as a reliable proxy for environmental conditions. The linear relationship between δ¹³C_DIC and δ¹³C_aragonite (r² = 0.97, p < 0.0001, RMSE = 0.18) was:

δ¹³C_DIC=1.15(±0.05)∗δ¹³C_aragonite-0.85(±0.04)     

Restructuring of Hog Farming in North Carolina: Explosion and Implosion

Over the past six years hog farming in North Carolina has undergone a significant restructuring. For most of this century raising hogs was a casual farm activity found throughout the state. During the past decade hog farming has been transformed along industrial-corporate lines. In the process, the swine population has expanded rapidly (exploded) and simultaneously collapsed in geographical bounds (imploded). This paper examines the linkage between the development of the industrial-corporate hog farming regime, the rapid growth in hog populations, and the geographical concentration of hog production in a newly emerging high-density hog production district in the south central area of the Coastal Plain region.     

Combined electrical resistivity tomography and magnetic resonance sounding investigation of the surface-water/groundwater interaction in the Urema Graben,Mozambique

This study focusses on the hydrogeology of Urema Graben, especially possible interactions between surface water and groundwater around Lake Urema, in Gorongosa National Park (GNP). Lake Urema is the only permanent water source for wildlife inside GNP, and there are concerns that it will disappear due to interferences in surface-water/groundwater interactions as a result of changes in the hydraulic environment. As the lake is the only permanent water source, this would be a disaster for the ecosystem of the park. The sub-surface geology in Urema Graben was investigated by 20 km of electrical resistivity tomography (ERT) and three magnetic resonance sounding (MRS) surveys. The average depth penetration was 60 and 100 m, respectively. The location of the ERT lines was decided based on general rift morphology and therefore orientated perpendicular to Urema Graben, from the transitional areas of the margins of the Barue platform in the west to the Cheringoma plateau escarpments in the east. ERT and MRS both indicate a second aquifer, where Urema Lake is a window of the first upper semi-confined aquifer, while the lower aquifer is confined by a clay layer 30–40 m thick. The location and depth of this aquifer suggest that it is probably linked to the Pungwe River which could be a main source of recharge during the dry season. If a dam or any other infra-structure is constructed in Pungwe River upstream of GNP, the groundwater level will decrease which could lead to drying out of Urema Lake.     

The history and fate of the Nubian Sandstone Aquifer springs in the oasis depressions of the Western Desert,Egypt

Extraction of groundwater for agriculture has resulted in the loss of springs across arid regions of the globe. The history and fate are recorded of the artesian springs of Egypt’s Western Desert, from ancient times to the present, spanning the rise and fall of the great civilisations from the Pharoanic dynasties to Persian, Greek and Roman conquests. The study area includes oases Kharga, Dakhla, Bahriya, Farafra and Siwa, and several outer and small oases around Siwa and the edge of the Qattara Depression. The region is hyper-arid, receiving 10 mm or less average annual precipitation and evaporation rates are in the vicinity of 3,000 mm/a. Groundwater in the oases is largely derived from bores discharging from the Nubian Sandstone Aquifer. Based on an extensive survey, conducted for the first time, attention is drawn to the rapid demise of springs as a result of modern irrigation schemes which continue to deplete groundwater supplies.     

Late Holocene Environmental Reconstructions from Lake Solai,Kenya

Playa lake systems tend to be overlooked archives of paleoenvironmental change due to the likelihood of a short and intermittent record of deposition. Groundwater-fed wetlands associated with these climate-sensitive playas, however, preserve changes in hydrologic budget and are thus valuable archives for semiarid regions. This study examines the paleoecological record of a groundwater-fed wetland from Lake Solai, Kenya. Biological proxies are used to reconstruct paleoenvironmental change and climate impacts over the past millennium. Dry conditions persisted between CE 1115 and 1490, followed by wetter conditions during the Little Ice Age. Near surface sediments indicate increasing anthropogenic impact through pastoralism.