ABSTRACT: Activities such as agriculture, silviculture, and mining contribute nonpoint pollution to Alabama's streams through polluted runoff and excessive sedimentation. Highly erodible soils characteristic of the Choctawhatchee‐Pea Rivers watershed, combined with intense rainfall and land use practices, contribute large amounts of sediment to streams. Biological monitoring can reflect the acute impacts of pollutants as well as prolonged effects of habitat alteration, and development of biological criteria is important for the establishment of enforceable laws regarding nonpoint source pollution. Macroinvertebrates were collected from 49 randomly selected sites from first through sixth‐order streams in the Choctawhatchee‐Pea Rivers watershed and were identified to genus level. Thirty‐eight candidate metrics were examined, and an invertebrate community index (ICI) was calibrated by eliminating metrics that failed to separate impaired from unimpaired streams. Each site was scored with those metrics, and narrative scores were assigned based on ICI scores. Least impacted sites scored significantly lower than sites impacted by row crop agriculture, cattle, and urban land uses. Conditions in the watershed suggest that the entire area has experienced degradation through past and current land use practices. An initial validation of the index was performed and is described. Additional evaluations of the index are in progress. 相似文献
Consumption of marine fish is a major route of toxic methyl mercury (MeHg) exposure to ocean apex predators and human populations. Here we explore the influence of trophic structure on total mercury (Hg) accumulation in red snapper (RS, Lutjanus campechanus) and gray snapper (GS, Lutjanus griseus) from the coastal Louisiana region of the Gulf of Mexico, west of the Mississippi River. The objectives of this investigation were to: (1) determine the effectiveness of the use of offshore recreational fishing charter boats and marinas as sources of fish samples and (2) compare species differences in Hg bioaccumulation, trophic position, and carbon sources. Our data show that length-normalized Hg concentrations (> or = 97% as MeHg in tissue of both species) were 230% greater in GS in comparison to RS collected from the same general area. Stable C and N isotope signatures (delta15N and delta13C) indicate that GS occupy a slightly higher trophic position (approximately 30% of one trophic position higher) on the Gulf food web in comparison to RS and that GS appear to incorporate higher trophic positioned prey, continually and at smaller sizes. Mercury was strongly correlated with combined delta15N and delta13C in pooled species data, arguing that most of the substantial difference in Hg bioaccumulation between RS and GS can be explained by modest differences in their trophic position and, to a lesser degree, carbon sources, which had low variation and high overlap among species. These observations demonstrate that even minor to moderate differences in trophic position and food habits in sympatric species can create relatively large differences in bioaccumulation regimes and underscores the importance of quantitative characterization of trophic structure in marine MeHg bioaccumulation studies. 相似文献
Watershed development is the focus of poverty alleviation programs in rural India. Watershed projects aim to solve problems
of externalities, but they also create their own externalities, which cause uneven distribution of costs and benefits that
undermine project objectives and harm the poor. Numerous approaches exist to internalize externalities, including awareness
creation, moral suasion, investment subsidies, regulatory limits and fines, indirect benefits, mergers, and recent innovations
like payment for environmental services and cap and trade. These can be judged on several criteria; the best approach would
solve the problem cost effectively and help or at least not hurt poor people. Watershed projects in India were examined to
identify the approaches taken to internalize watershed externalities. Investment subsidies and indirect employment benefits
are the least effective approaches theoretically, but they are the most commonly applied, most likely because they are easy
to administer and bring popular short term gains. Some theoretically favorable approaches that have been used elsewhere, such
as payment for environmental services, may not work as well in India due to high transaction costs. However, one key innovation
that easily could be applied in India is to make investment subsidies contingent on performance. Legal support and property
rights reform would be needed for other favorable approaches. 相似文献
Concerns over elevated nitrate (NO3-) levels found in groundwater near former biosolid stockpiling locations resulted in the Maine Department of Environmental Protection (MDEP) imposing stricter regulations governing the stockpiling of biosolids in October 2002. The goals of this study were to measure the amount and speciation of nitrogen (N) and trace metals leaving stockpiled biosolids and travelling through the soil column. The biosolids were placed on plastic-lined cells to collect all leachate. Ammonium (NH4+), ranging from 2000 to 4900 mg L(-1), was the dominant N species (90% of total N) in the leachate from the Class B lime-stabilized biosolids in the lined cell experiment. Nitrate (NO3-) and nitrite (NO2-) concentrations were negligible, remaining below 0.25 and 0.1 mg L(-1), respectively. Dissolved organic carbon (DOC) concentrations as high as 8900 mg L(-1) and chemical oxygen demand (COD) as high as 37 000 mg L(-1) were measured in the leachate leaving the lined cell. Fifteen zero-tension pan lysimeters (ZTP-lysimeter) were installed in a 90 m2 plot at depth intervals of 30, 60, and 100 cm. Leachate passing through the soil column underlying the biosolids stockpile was collected in the ZTP-lysimeters. The average ZTP-lysimeter NH4+ concentrations ranged from 1400 mg L(-1) at 60 cm depth to 145 mg L(-1) at 90 cm depth. The average ZTP-lysimeter DOC concentrations ranged from 2000 mg L(-1) at 60 cm to 525 mg L(-1) at 90 cm. Trace metal determinations of the leachate collected from the lined cell and ZTP-lysimeters showed arsenic loading rates exceeded the state limits of 0.5 kg ha(-1) year(-1) by an order of magnitude. Arsenic concentrations were in excess of several thousand milligrams per litre in the lined-cell leachate and several hundred milligrams per litre in the ZTP-lysimeters as deep as 90 cm under the biosolid stockpile. Phosphorus, iron and manganese in excess of several thousand milligrams per litre were observed in both the lined-cell leachate and ZTP-lysimeters. Significant concentrations of other trace metals were found at depth in the zero-tension ZTP-lysimeter plot. Trace metals were largely mobilized by the DOC from the biosolids and due to the presence of anaerobic environment, especially in the underlying soil. 相似文献
When conservation strategies require new, field‐based information, practitioners must find the best ways to rapidly deliver high‐quality survey data. To address this challenge, several rapid‐assessment approaches have been developed since the early 1990s. These typically involve large areas, take many months to complete, and are not appropriate when conservation‐relevant survey data are urgently needed for a specific locale. In contrast, bioblitzes are designed for quick collection of site‐specific survey data. Although bioblitzes are commonly used to achieve educational or public‐engagement goals, conservation practitioners are increasingly using a modified bioblitz approach to generate conservation‐relevant data while simultaneously enhancing research capacity and building working partnerships focused on conservation concerns. We term these modified events expert bioblitzes. Several expert bioblitzes have taken place on lands of conservation concern in Southern California and have involved collaborative efforts of government agencies, nonprofit organizations, botanic gardens, museums, and universities. The results of expert bioblitzes directly informed on‐the‐ground conservation and decision‐making; increased capacity for rapid deployment of expert bioblitzes in the future; and fostered collaboration and communication among taxonomically and institutionally diverse experts. As research and conservation funding becomes increasingly scarce, expert bioblitzes can play an increasingly important role in biodiversity conservation. 相似文献
The continuously growing global demands on a finite land resource will require better strategic policies and management of trade-offs to avoid conflicts between different land-use sectors. Visions of the future can support strategic planning by stimulating dialogue, building a consensus on shared priorities and providing long-term targets. We present a novel approach to elicit stakeholder visions of future desired land use, which was applied with a broad range of experts to develop cross-sectoral visions in Europe. The approach is based on (i) combination of software tools and facilitation techniques to stimulate engagement and creativity; (ii) methodical selection of stakeholders; (iii) use of land attributes to deconstruct the multifaceted sectoral visions into land-use changes that can be clustered into few cross-sectoral visions, and (iv) a rigorous iterative process. Three cross-sectoral visions of sustainable land use in Europe in 2040 emerged from applying the approach in participatory workshops involving experts in nature conservation, recreation, agriculture, forestry, settlements, energy, and water. The three visions—Best Land in Europe, Regional Connected and Local Multifunctional—shared a wish to achieve a land use that is sustainable through multifunctionality, resource use efficiency, controlled urban growth, rural renewal and widespread nature. However, they differ on the scale at which land services are provided—EU-wide, regional or local—reflecting the land-sparing versus land-sharing debate. We discuss the usefulness of the approach, as well as the challenges posed and solutions offered by the visions to support strategic land-use planning.
Abstract: The U.S. Environmental Protection Agency is charged with establishing standards and criteria for assessing lake water quality. It is, however, increasingly evident that a single set of national water quality standards that do not take into account regional hydrogeologic and ecological differences will not be viable as lakes clearly have different inherent capacities to meet such standards. We demonstrate a GIS‐based watershed classification strategy for identifying groups of Nebraska reservoirs that have similar potential capacity to attain a certain level of water quality standard. A preliminary cluster analysis of 78 reservoirs was performed to determine the potential number of Nebraska reservoir groups. Subsequently, a Classification Trees method was used to refine number of classes, describe the structure of reservoir watershed classes, and to develop a predictive model that relates watershed conditions to reservoir classes. Results suggest that Nebraska reservoirs can be represented by nine classes and that soil organic matter content in the watershed is the most important single variable for segregating the reservoirs. The cross‐validation prediction error rate of the Classification Tree model was 26.3%. Because all geospatial data used in this work are available nationally, the method could be adopted throughout the U.S. Hence, this GIS‐based watershed classification approach could provide water resources managers an effective decision‐support tool in managing reservoir water quality. 相似文献
This paper focuses on the ethical justifiability of patents on Genetically Modified (GM) crops. I argue that there are three
distinguishing features of GM crops that make it unethical to grant patents on GM crops, even if we assume that the patent
system is in general justified. The first half of the paper critiques David Resnik’s recent arguments in favor of patents
on GM crops. Resnik argues that we should take a consequentialist approach to the issue, and that the best way to do so is
to apply the Precautionary Principle, and that the Precautionary Principle, in this case, supports patents on GM crops. I
argue that his argument in favor of a consequentialist treatment is invalid; his Precautionary Principle in any case appears
to be incompatible with consequentialism; and his conception of reasonable precautions is too ill-defined to have any argumentative
purchase. In the second half of the paper, I argue against GM crop patents, on three grounds. First, there is insufficient
evidence to say whether allowing patents on GM crops will make research go faster than not having patents, whilst there is
a good reason to think that, other things being equal, a society that allows patents on GM crops will be less just than one
that does not. Second, even assuming that patents on GM crops will increase the pace of GM crop research, there is no social
need to do so. Third, patents on GM crops will frequently have ethically unacceptable side effects. 相似文献
The traditional vision of the role science should play in policy making is of a two stage process of scientists first finding
out the facts, and then policy makers making a decision about what to do about them. We argue that this two stage process
is a fiction and that a distinction must be drawn between pure science and science in the service of public policy. When science
is transferred into the policy realm, its claims to truth get undermined because we must abandon the open-ended nature of
scientific inquiry. When we move from the sphere of science to the sphere of policy, we pick an arbitrary point in the open-ended
scientific process, and ask our experts to give us the answer. The choice of the endpoint, however, must always be arbitrary
and determined by non-scientific factors. Thus, the two stages in the model of first finding the facts, and then making a
decision about what to do, cannot be clearly separated. The second stage clearly affects the first. This conclusion will have
implications about existing scientific policy institutions. For example, we advocate that the environmental assessment process
be radically overhauled, or perhaps even let go. It will be our position that ultimately a better model for the involvement
of scientists in public policy debates is that of being participants in particular interest groups (“hired guns”), rather
than as supposedly unbiased consultants to decision-makers. 相似文献