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581.
This paper reports the bioaccumulation of three PCBs (2,4′-dichlorobiphenyl, 2,4,6,2′-tetrachlorobiphenyl and 2,4,6,2′,4′-pentachlorobiphenyl) by the green alga under various conditions. A probable pattern of the bioconcentration mechanism is suggested. No metabolites were extracted from algae or water 6 days after incubation with PCBs. 相似文献
582.
Oviposition behavior of insects has associated fitness costs related to the probability that females survive to oviposit.
During summer 2003, we observed the oviposition behavior and compared the mortality rates of females of 17 mayfly species
in one western Colorado watershed. We dissected adult females collected on terrestrial sticky traps, in drift nets submerged
in streams, and in stomachs of brook trout to determine whether the mayflies had oviposited before capture, drowning, or consumption.
Females oviposited by either splashing on the water surface releasing all their eggs (splashers), dropping their eggs from
the air (bombers), dipping their abdomens multiple times releasing a few eggs at a time (dippers), landing on rocks and ovipositing
on the undersides (landers), or floating downstream while releasing their eggs (floaters). Almost 100% of lander and 50% of
dipper females had not oviposited when captured on sticky traps, increasing their vulnerability to preoviposition mortality
by aerial predators compared to mayflies with other behaviors. In contrast, most females had laid their eggs before drowning
or being eaten by a fish (50–90%). However, groups with oviposition behaviors most exposed to the water surface (floaters,
then splashers, dippers, and landers) were more vulnerable to drowning before completing oviposition. In addition, splashers
and floaters were most vulnerable to predation by brook trout before ovipositing. These data suggest that fitness costs associated
with preoviposition mortality may be considerable depending on mayfly oviposition behavior. Furthermore, previously demonstrated
benefits of low predation rates on eggs of lander species may be offset in part by costs to female survival.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
583.
The Environmental Auditing Roundtable (EAR) is the single largest professional organization in the world, representing over 900 members. Built on a tradition of promoting environmental auditing through openly sharing experiences in the field of safety, health, and environmental auditing, the organization in recent years has significantly expanded its influence on auditing practices both nationally and internationally by monitoring audit activities and participating in the development of audit policy, regulation, standardization, and the certification of environmental auditors. This article describes the origin and evolution of the organization from meeting the needs of the membership to addressing the needs of external national and international stakeholders. 相似文献
584.
Many organizations in environmental fields stand to benefit from the use of a geographic information system (GIS). Selecting
a GIS to implement within an organization can be a difficult task that is often required of people with little experience
using a GIS. A framework for evaluating competing GIS considers cost, functionality, ease of use, future stability, development
potential, support availability, and maintenance costs. Initial cost involves more than the actual purchase price of hardware
and software; it includes the cost of building the data base and training users within the organization. Functionality refers
to the depth and breadth of capabilities of a GIS. Issues involved in evaluating functionality include the appropriateness
of raster vs vector processing and the ability to add your own software. Ease of use is important, but there is generally
a trade-off with functionality. The degree of centralization of use of the GIS within the organization affects requirements
for ease of use. GIS are rapidly evolving, and as a result it is important to select a system with high potential for future
development. With the proliferation of companies offering GIS it is important to select one that is likely to survive and
prosper. Similarly, the ability to find support in the forms of technical help, advice, and possibly even skilled employees
can be significant. 相似文献
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