Climate change: A looming challenge for fisheries management in southern Africa

It is now widely accepted that the earth's climate is changing under the influence of anthropogenic activities. A number of key changes in the earths atmosphere and ocean have already been detected (including increasing global surface temperature, rising sea levels, increases in incident UV radiation, changes in average annual precipitation, and increases in the variability and intensity of extreme weather events, among others), while speculation regarding future changes is rife. The implications of global climate change for fish stocks and fisheries is of concern to many scientists, but little effort has been made to incorporate observed changes or event such thinking into management models and paradigms. This paper summarises available evidence linking the production of key greenhouse gases with observed and future projected changes in the earth's climate, specifically in respect of a number of key atmospheric and oceanographic parameters likely to affect fish stocks in South Africa (temperature, pressure/wind fields, CO₂ concentration, rainfall, mean sea level and UV radiation). It also explores likely effects of these changes on fish stocks and key fishery sectors. In addition, it highlights a number of positive steps that be taken by management authorities to ensure that they and the fishing communities for which they are responsible are in the best possible position to deal with the effects of changing global climate as they become manifest.     

IV. Bücher- und Zeitschriftenschau

Ohne Zusammenfassung     

Major and trace element provenance signatures in stream sediments from the Kando River, San'in district, southwest Japan

Abstract Basement rocks in the catchment of the Kando River in southwest Japan can be divided into two main groups. Paleogene to Cretaceous felsic granitoids and volcanic rocks dominate in the upstream section, and more mafic, mostly Miocene volcanic and volcaniclastic rocks occur in the downstream reaches. Geochemically distinctive Mount Sambe adakitic volcanic products also crop out in the west. X‐ray fluorescence analyses of major elements and 14 trace elements were made of two size fractions (<180 and 180–2000 µm) from 86 stream sediments collected within the catchment, to examine contrasts in composition between the fractions as a result of sorting and varying source lithotype. The <180 µm fractions are depleted in SiO₂ and enriched in most other major and trace elements relative to the 180–2000 µm fractions. Na₂O, K₂O, Ba, Rb and Sr are either depleted relative to the 180–2000 µm fractions, or show little contrast in abundance. Sediments from granitoid‐dominated catchments are distinguished by greater K₂O, Th, Rb, Ba and Nb than those derived from the Miocene volcanic rocks. Granitoid‐derived <180 µm fractions are also enriched in Zr, Ce and Y. Sediments derived from the Miocene volcanic rocks generally contain greater TiO₂, Fe₂O₃*, Sc, V, MgO and P₂O₅, reflecting their more mafic source. Sediments containing Sambe volcanic rocks in their source are marked by higher Sr, CaO, Na₂O and lower Y, reflecting an adakitic signature that persists into the lower main channel, where compositions become less variable as the bedload is homogenized. Normalization against source averages shows that compositions of the 180–2000 µm fractions are less fractionated from their parents than are the <180 µm fractions, which are enriched for some elements. Contrast between the size fractions is greatest for the granitoid‐derived sediments. Weathering indices of the sediments are relatively low, indicating source weathering is moderate, and typical of temperate climates. Some zircon concentration has occurred in granitoid‐derived <180 µm fractions relative to 180–2000 µm counterparts, but Th/Sc and Zr/Sc ratios overall closely reflect both provenance and homogenization in the lower reaches.     

Precipitation in the Venezuelan Andes in the context of regional climate

Summary Rainfall regimes are primarily unimodal in central and eastern Venezuela but bimodal (peaks in May–June and September-October-November with a minimum in July–August) in the northwest. There is a sharp transition across the Andes suggesting a topographic-circulation connection. However, a mid-summer minimum also occurs at other locations in Venezuela and Central America during individual years. This paper addresses the nature and control of the regimes including the role of large-scale circulation features and convection as indicated by outgoing longwave radiation data. Altitudinal characteristics of precipitation in the Andes and their spatial variability are also investigated. The development of the minimum within the rainy season annual cycle is shown to be related to the combined effects of the evolution of sea surface temperatures in the east Pacific warm pool and reinforced in the area of the Andes by enhanced easterlies during July and August.Abbreviations used in text ENSO El Nino-Southern Oscillation - EPWP East Pacific Warm Pool - ITCZ Inter-tropical Convergence Zone - MEI Multivariate ENSO Index - MSM Mid-Summer Minimum - NCEP National Centers for Environmental Prediction - OLR Outgoing Longwave Radiation - SOI Southern Oscillation Index - SST Sea Surface Temperature With 13 Figures     

PHREEQC在地下水溶质反应-运移模拟中的应用

由于地下水污染的加剧,对地下水中污染物运移规律的研究日益受到重视。地下水中的溶质在运移过程中伴随着溶质组分间的化学反应,因此需要建立地下水溶质运移与化学反应的耦合模型。PHREEQC是近年来发展起来的描述局部平衡反应、动态生物化学反应的水文地球化学模拟软件。本文利用该模拟软件对一维地下水流动过程中溶质离子交换反应和动态氧化还原反应进行了模拟。结果表明,PHREEQC能够成功地进行溶质运移情况下复杂水化学反应模拟,但对于复杂地下水流和溶质运动的情况,有必要耦合其它的地下水流动和溶质运移软件来共同完成。     

Population Estimation Error and Its Impact on 1991–1999 Cancer Rates*

The error of closure in the 2000 census, or the difference between estimated and enumerated populations, poses special problems for public agencies that rely on census data. Nationally and at the state level, populations were only slightly underestimated, but underestimations were high in rapidly growing counties in the South and intermontaine West, as well as in New York City. Race‐specific estimates proved far less reliable, with severe overestimates and underestimates of all racial groups in various counties nationwide. We offer explanations for the estimation error and discuss its impact on cancer rates and trends and its implications for cancer surveillance research.