Geochemical evaluation of metals in groundwater at long‐term monitoring sites and active remediation sites

At many sites, long‐term monitoring (LTM) programs include metals as chemicals of concern, although they may not be site‐related contaminants and their detected concentrations may be natural. At other sites, active remediation of organic contaminants in groundwater results in changes to local geochemical conditions that affect metal concentrations. Metals should be carefully considered at both types of sites, even if they are not primary contaminants of concern. Geochemical evaluation can be performed at LTM sites to determine if the monitored metals reflect naturally high background and, hence, can be removed from the analytical program. Geochemical evaluation can also be performed pre‐ and post‐treatment at active remediation sites to document the effects of organics remediation on metals and identify the processes controlling metal concentrations. Examples from both types of sites are presented in this article. © 2008 Wiley Periodicals, Inc.     

A priority-ranking strategy for threatened species?

Summary The rate of extinction has accelerated to the point where we are probably losing one species per day right now, and we could well lose one million of Earth's 5–10 million species by the year 2000, and a good many more within the early decades of the next century. Plainly we cannot assist all species that face extinction within the foreseeable future. Conservationists have limited resources at their disposal, in the way of finance, scientific skills, and the like. Even were these resources to be increased several times over, we could not hope to save more than a proportion of all species that appear doomed to disappear: the processes of habitat disruption are too strongly underway to be halted in short order. But when we allocate funds to safeguard one species, we automatically deny those funds to other species. Already we support only a small fraction of all species under threat, and we may soon find ourselves in a situation where we can assist only a very marginal number of species facing extinction. Thus a key question arises: how are we to allocate our scarce resources in the most efficient way to safeguard species? Indeed we may now have reached a stage where there is merit in determining which species are most deserving of a place on the planet. Agonizing as it will be to make choices along these lines, conservation strategy should be as systematically selective as possible. This means that we should design analytic methodologies to enable us to assign our conservation resources to achieve maximum return in terms of numbers of species protected. In essence, a triage strategy. An expanded approach along these lines postulates a quantum advance in our planning of responses to the growing threatened-species problem: while the techniques of the past have certainly helped the situation, we cannot confront the much greater challenges of the future with an attitude of the same as before, only more so—the future will not be a simple extrapolation of the past, but will represent a qualitatively larger set of problems, which require an appropriately scaled-up response in our save-species campaigns.Dr Norman Myers is an expert in the study of endangered species and ecosystems. He is an international consultant in Environment and Development. This paper is based in part on findings of a project that he conducted for the World Wildlife Fund—US, to which grateful acknowledgment is made. The responsibility for all conclusions and recommendations remains, of course, with the author.     

The human cervical spine in tension: effects of frame and fixation compliance on structural responses

There is little data available on the responses of the human cervical spine to tensile loading. Such tests are mechanistically and technically challenging due to the variety of end conditions that need to be imposed and the difficulty of strong specimen fixation. As a result, spine specimens need to be tested using fairly complex, and potentially compliant, apparati in order to fully characterize the mechanical responses of each specimen. This, combined with the relatively high stiffness of human spine specimens, can result in errors in stiffness calculations. In this study, 18 specimen preparations were tested in tension. Tests were performed on whole cervical spines and on spine segments. On average, the linear stiffness of the segment preparations was 257 N/mm, and the stiffness of the whole cervical spine was 48 N/mm. The test frame was found to have a stiffness of 933 N/mm. Assembling a whole spine from a series combination of eight segments with a stiffness of 257 N/mm results in an estimated whole spine stiffness of 32.1 N/mm (32% error). The segment stiffnesses were corrected by assuming that the segment preparation stiffness is a series combination of the stiffnesses of the segment and the frame. This resulted in an average corrected segment stiffness of 356 N/mm. Taking the frame compliance into account, the whole spine stiffness is 51 N/mm. A series combination of eight segments using the corrected stiffnesses results in an estimated whole spine stiffness of 45.0 N/mm (12% error). We report both linear and nonlinear stiffness models for male spines and conclude that the compliance of the frame and the fixation must be quantified in all tension studies of spinal segments. Further, reported stiffness should be adjusted to account for frame and fixation compliance.     

Threatened biotas: "Hot spots" in tropical forests

Summary The mass-extinction episode underway is largely centred on tropical forests, insofar as they contain at least half of all Earth's species and they are being depleted faster than any other biome. But species distributions and depletion patterns are anything but uniform throughout the biome. This paper identifies 10 areas that, a) are characterised by exceptional concentrations of species with high levels of endemism and b) are experiencing unusually rapid rates of depletion. While these "hotspot" areas comprise less than 3.5 percent of remaining primary forests, they harbour over 34 000 endemic plant species (27 percent of all plant species in tropical forests and 13 percent of all plant species worldwide). They also feature 700 000 endemic animal species and possibly several times more. Unfortunately, they appear likely to lose 90 percent of their forest cover as soon as the end of the century or shortly thereafter, causing the extinction of almost 7 percent of Earth's plant species and at least a similar proportion of animal species, this occurring in only 0.2 percent of Earth's land surface. By concentrating on such areas where needs are greatestand where the pay-off from safeguard measures would also be greatest, conservationists can engage in a more systematised response to the challenge of largescale extinctions impending in tropical forests.Professor Norman Myers is a consultant in environment and development. He is author of many important environmental books, an Advisory Board Member, and a regular contributor toThe Environmentalist.     

Consumption in relation to population,environment and development

The Earth has enough for everyone's need but not for everyone's greed. (Gandhi, 1947). A statement made when the world's population was 45% and global consumption was 25--30% of today's figures.The triad of problems, population, environment and development, is now being joined by a fourth, consumption. In many respects this could prove to be the least tractable of the four interlinked problems, since consumption patterns and expectations are deeply entrenched in most societies and cultures. However, change will come, whether by design or by default. The present consumption--or rather, excessive and wasteful consumption--on the part of rich nations cannot be sustained for environmental reasons alone, as exemplified by the fossil fuel/carbon dioxide connection to global warming. Nor can the present consumption in developing nations--meagre as these levels are for the 3 billion people who account for only 5% of the global economy--climb to levels desired by many if only because of the sheer numbers of their potential consumers. At the same time, it is increasingly the case that in the food sector, as in certain other sectors, over-consumption among rich communities can lead to under-consumption among poor communities. Fortunately, there are many opportunities to relieve consumption pressures, whether through enhanced technology or shifts in lifestyles, both of which can be promoted by a variety of policy initiatives.     

Finding upper-level sets in cellular surface data using echelons and saTScan

Across a spectrum of contemporary contexts from public health to landscape ecology and natural resources, there is need for objective determination of elevated occurrence in phenomena such as disease incidence and biodiversity. Occurrences of such phenomena constitute response surfaces, but data regarding the surface is typically acquired in a cellular framework. The cells may comprise a regular grid, or may be of irregular shapes such as counties in which statistics are collected. Echelons are a topologically based approach to systematic determination of spatial structure in a step surface. Spatial scan statistics are a probability-based approach to the same issue when interest lies in a rate variable. Here we examine the use of echelons both separately and in conjunction with the SaTScan implementation of spatial scan statistics for purposes of determination and visualization of upper-level sets. Consideration is given to both conventional geographic space and to the cellular pseudo-space of contingency tables for ordered categorical variables. Received: August 2002 / Revised: July 2005