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301.
Ephrime B. Metillo Ronald Villanueva Ken-ichi Hayashizaki Satoru Tamada Masayoshi Sano Shuhei Nishida 《Chemistry and Ecology》2019,35(2):143-163
The role of zooplankton in a tropical seagrass ecosystem was investigated in milkfish farms pollution-impacted and -unimpacted seagrass beds in Santiago Island coral reefs, Northwestern Philippines. The aim was to compare between the two sites: (1) abiotic factors and zooplankton community parameters, and (2) the trophic structure using C and N stable isotopes. Low water (98–119?mV) and sediment (–121 to ?138?mV) Oxidation Reduction Potential values indicated a reducing environment in the impacted site. Zooplankton in the impacted site showed the typical community response to eutrophication (low diversity, but high total abundance due to the dominance of the cyclopoid copepod Oithona oculata), generally few elevated δ15N values, but a significant shift towards depleted 13C due to the organic enrichment of fish-farm feeds. Apart from suggesting a highly complex food web with POM and zooplankton as main food sources in the unimpacted site, the Bayesian mixing model simulation generated reduced complexity in feeding interactions between basal sources, zooplankton, and fish including adults of a key fish species, Siganus fuscescens, in the impacted sites. In this study, C and N stable isotope analysis has clarified the importance of zooplankton as fish prey in a seagrass bed food web. 相似文献
302.
303.
Stanley N. Wiemeyer Ronald M. Jurek John F. Moore 《Environmental monitoring and assessment》1986,6(1):91-111
California condor (Gymnogyps californianus) foods and feathers, and turkey vultures (Cathartes aura), common ravens (Corvus corax), and their eggs were collected within the condor range to determine exposure of condors to environmental contaminants. Samples were analyzed for organochlorines and trace elements. Food items contained low concentrations of organochlorines and generally low concentrations of lead. DDE was detected in all vulture carcasses and nearly all raven carcasses at generally moderate concentrations. Other organochlorines occurred infrequently in carcasses and generally at low concentrations. Turkey vulture eggshells were 16% thinner than the pre-DDT mean; there was no change in shell thickness of raven eggs. Vulture eggs contained an average of 6.9 ppm DDE and two contained excessive concentrations of endrin. DDE concentrations were low in raven eggs. Residues of As, Cd, Cr, Cu, Fe, Hg, Ni, Se, Tl, and Zn in tissues of vultures and ravens appeared normal when compared with reference values for other species. Lead concentrations in bone of turkey vultures and feathers of condors appeared to be elevated above normal background concentrations in some cases. Current exposure of condors to organochlorines appears low; however, we are concerned about the excessive exposure of turkey vultures to organochlorines, possibly in Central America. Lead exposure to vultures and condors has occurred, but its significance to their populations is unknown. 相似文献
304.
Ronald L. Rutowski 《Behavioral ecology and sociobiology》1980,7(2):113-117
Summary The willingness of some females of the checkered white butterfly to approach and chase conspecifies was studied in the field. Both virgin and mated females were observed approaching and chasing conspecifics. Such responses to males result in the solicitation or continuation of male courtship attempts, which in turn may lead to copulation.Mated females that approached conspecifics had significantly smaller spermatophores than females in a random sample from the same population.Females that approached tethered animals spent more time chasing tethered males than tethered females. Females with small spermatophores spent more time chasing tethered males than did females with larger spermatophores.These results confirm the hypothesis that mated females that approach and chase conspecifics are doing so in an effort to solicit male courtship attempts and to potentially receive a fresh spermatophore. The selective forces favoring courtship solicitation by females are discussed. 相似文献
305.
Gary E. Quinton Ronald J. Buchanan David E. Ellis Stephen H. Shoemaker 《补救:环境净化治理成本、技术与工艺杂志》1997,7(4):7-16
DuPont has developed a method to compare, on a consistent economic basis, in situ remediation technologies. The methodology employs a template site with a perchloroethylene plume 1000 ft long by 400 ft wide, and incorporates various aquifer thicknesses and depths. Variables considered in the methodology include duration of the remediation; estimated engineering and flow/transport modeling costs; equipment costs; and operation, maintenance, and monitoring costs. In this article, substrate-enhanced anaerobic bioremediation, intrinsic bioremediation, in situ permeable reactive barriers, and pump-and-treat systems are evalutated. Cost metrics include present cost, cost per pound of contaminant removed, and cost per 1000 gals treated, using a discounted cash-flow analysis. Costs of the remedial alternatives increase starting from intrinsic bioremediation, to substrate-enhanced anaerobic bioremediation, to a biological substrate-enhanced anaerobic barrier, to in situ permeable reactive barriers, to pump-and-treat systems with air stripping and carbon adsorption. 相似文献
306.
Ronald K. Patterson 《环境质量管理》1992,2(1):57-61
Quality assurance (QA) and quality control (QC) are basic components of a TQEM program. All too often these functions are loosely defined and used interchangeably. Yet, the quality of outputs and services strongly depends on the caliber of the communications between the “customer” and the “supplier.” A clear understanding of customer needs and expectations is essential to selecting and applying suitable QA and QC. Planning, implementing, and assessing all play a major part in the quality of final outputs. A clear understanding of the customer/supplier relationship and the functional roles played by each is essential to a successful TQEM program. This article identifies, clarifies, and simplifies the quality management responsibilities of the customer and the supplier. The ideas presented are applicable in all work environments, including research and development (R&D). 相似文献
307.
Using the methodology of policy capturing, this research identifies the role that performance, time on the job, commitment of long-term employment and employability play in judgment of termination fairness and employer obligations. Previous research (Rousseau and Anton, 1988) found that seniority and past commitments of long-term employment contributed significantly to judgments of termination fairness and obligation. The present study considered these variables along with performance (past, present and future potential) using 116 participants in human resource management courses. Results indicated that present performance, time on the job, and commitments affect judgments regarding termination fairness and obligation. Past and future performance, however, had no impact on these judgments. Implications of the findings for understanding employer and employee obligations are discussed. 相似文献
308.
Ronald L. Miller 《Journal of the American Water Resources Association》1978,14(6):1503-1506
ABSTRACT: Arizona's water pollution control program is based on authorties of Arizona Revised Statutes and Public Law 92–500, the Federal Water Pollution Control Act Amendments of 1972. The primary areas of this program are monitoring, facility inspections, plan review, planning, discharge permits and grants for the construction of publicly-owned waste water treatment facilities. The discharge permit program deals with control of point-source discharges and is administered by the United States Environmental Protection Agency. The planning and construction grants programs are administered by the State Water Quality Control Council and are implemented by the Bureau of Water Quality Control, which serves as staff to the Council. There are several challenges that face the State in this program. First is the adaptation of the “eastern law” to deal with Arizona's water quality problems. Second is to address problems caused by a long history of “laissez-faire” environmental quality management. Third is a mutual cooperation and coordination among the many entities involved in water resources management. Areas of particular interest in the State's program is the process setting water quality standards and the involvement of people of diversified backgrounds in the field of areawide planning under Section 208 of the Federal Water Pollution Control Act, which is primarily concerned with non-point sources of water pollution. 相似文献
309.
Ronald W. Matlin Martin T. Katzman 《Journal of the American Water Resources Association》1979,15(5):1308-1317
ABSTRACT: An economic analysis of the profitability of adopting solar photovoltaic energy systems for crop irrigation is undertaken. The economic, technological, and political uncertainties surrounding adoption are discussed with reference to their impact on anticipated profitability. On the assumption that the costs of producing photovoltaic modules follows a learning curve characteristic of other inventions, solar systems are likely to be viable for irrigation in some states by mid to late 1980s. A field test in Nebraska is described. 相似文献
310.