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191.
Upton Hatch Shrikant Jagtap Jim Jones Marshall Lamb 《Journal of the American Water Resources Association》1999,35(6):1551-1561
ABSTRACT: Climate change has the potential to have dramatic effects on the agricultural sector nationally and internationally as documented in many research papers. This paper reports on research that was focused on a specific crop growing area to demonstrate how farm managers might respond to climate-induced yield changes and the implications of these responses for agricultural water use. The Hadley model was used to generate climate scenarios for important agricultural areas of Georgia in 2030 and 2090. Linked crop response models indicated generally positive yield changes, as increased temperatures were associated with increased precipitation and CO2. Using a farm management model, differences in climate-induced yield impacts among crops led to changes in crop mix and associated water use; non-irrigated cropland received greater benefit since irrigated land was already receiving adequate moisture. Model results suggest that farm managers will increase cropping intensity by decreasing fallowing and increasing double cropping; corn acreage decreased dramatically, peanuts decreased moderately and cotton and winter wheat increased. Water use on currently irrigated cropland fell. The potential for increased water use through conversion of agriculturally important, but currently non-irrigated, growing areas is substantial. 相似文献
192.
193.
Simple molecular method to distinguish the identity of Calanus species (Copepoda: Calanoida) at any developmental stage 总被引:1,自引:0,他引:1
Diagnostic morphological characteristics of copepods of the genus Calanus are restricted largely to minor variations in secondary sex characteristics. This presents a persistent problem in the identification
of individuals to species level, especially for immature stages. We have developed a simple molecular technique to distinguish
between the North Atlantic Calanus species (C. helgolandicus, C. finmarchicus, C. glacialis and C. hyperboreus) at any life stage. Using the polymerase chain-reaction (PCR), the mitochodrial large subunit (16S) ribosomal RNA (rRNA)
gene was amplified from individual copepods preserved in ethanol. Subsequent digestion of the amplified products with the
restriction enzymes DdeI and VspI, followed by electrophoretic separation in 2% agarose (Metaphor, FMC Ltd), produced a characteristic pattern for each species.
The versatility of the method is demonstrated by the unambiguous identification to species of any life stage, from egg to
adult, and of individual body parts.
Received: 11 May 1998 / Accepted: 5 August 1998 相似文献
194.
Kathryn A. Powlen Jonathan Salerno Kelly W. Jones Michael C. Gavin 《Conservation biology》2023,37(4):e14058
Protected areas (PAs) are a commonly used strategy to confront forest conversion and biodiversity loss. Although determining drivers of forest loss is central to conservation success, understanding of them is limited by conventional modeling assumptions. We used random forest regression to evaluate potential drivers of deforestation in PAs in Mexico, while accounting for nonlinear relationships and higher order interactions underlying deforestation processes. Socioeconomic drivers (e.g., road density, human population density) and underlying biophysical conditions (e.g., precipitation, distance to water, elevation, slope) were stronger predictors of forest loss than PA characteristics, such as age, type, and management effectiveness. Within PA characteristics, variables reflecting collaborative and equitable management and PA size were the strongest predictors of forest loss, albeit with less explanatory power than socioeconomic and biophysical variables. In contrast to previously used methods, which typically have been based on the assumption of linear relationships, we found that the associations between most predictors and forest loss are nonlinear. Our results can inform decisions on the allocation of PA resources by strengthening management in PAs with the highest risk of deforestation and help preemptively protect key biodiversity areas that may be vulnerable to deforestation in the future. 相似文献
195.
Larson T Gould T Simpson C Liu LJ Claiborn C Lewtas J 《Journal of the Air & Waste Management Association (1995)》2004,54(9):1175-1187
As part of a large exposure assessment and health-effects panel study, 33 trace elements and light-absorbing carbon were measured on 24-hr fixed-site filter samples for particulate matter with an aerodynamic diameter <2.5 microm (PM2.5) collected between September 26, 2000, and May 25, 2001, at a central outdoor site, immediately outside each subject's residence, inside each residence, and on each subject (personal sample). Both two-way (PMF2) and three-way (PMF3) positive matrix factorization were used to deduce the sources contributing to PM2.5. Five sources contributing to the indoor and outdoor samples were identified: vegetative burning, mobile emissions, secondary sulfate, a source rich in chlorine, and a source of crustal-derived material. Vegetative burning contributed more PM2.5 mass on average than any other source in all microenvironments, with average values estimated by PMF2 and PMF3, respectively, of 7.6 and 8.7 microg/m3 for the outdoor samples, 4 and 5.3 microg/m3 for the indoor samples, and 3.8 and 3.4 microg/m3 for the personal samples. Personal exposure to the combustion-related particles was correlated with outdoor sources, whereas exposure to the crustal and chlorine-rich particles was not. Personal exposures to crustal sources were strongly associated with personal activities, especially time spent at school among the child subjects. 相似文献
196.
Wang Meichen Rivenbark Kelly J. Phillips Timothy D. 《Environmental science and pollution research international》2023,30(5):11417-11430
Environmental Science and Pollution Research - The co-occurrence of mixtures of glyphosate (GLP) and aminomethylphosphonic acid (AMPA) in contaminated water, soil, sediment, and plants is a cause... 相似文献
197.
Assessment of aquatic macroinvertebrates is a critical component of many watershed monitoring programs and passive samplers are often used to collect long-term site data, especially in environments where active sampling is not possible. However, standard passive samplers can be expensive and lost in extreme conditions. We developed a sampler using plastic soda bottles (PSB) filled with river rock and compared its effectiveness with standard Hester-Dendy samplers in both lotic and lentic environments. Abundance, taxa richness, and macroinvertebrate composition showed no significant differences between sampler types in either habitat type. PSB samplers, which can be constructed for less than one dollar each, collected the same number of organisms and represented the same diversity as Hester-Dendy devices that cost around $38 each. In studies where funds are limited, PSB samplers appear to be suitable for passive monitoring. 相似文献
198.
Gwen E. Jones 《组织行为杂志》1999,20(7):1057-1072
Using a 2 × 2 × 2 experimental design and data from 158 subjects, this study assessed the effects of three romance participant characteristics and respondent gender on reactions to working with team members involved in a hierarchical workplace romance. The romance participant characteristics included: (a) marital status of the team leader (married versus single); (b) marital status of a coworker (married versus single); and (c) gender of the team leader–coworker dyad (male–female versus female–male). Significant effects were found for team leader marital status, coworker marital status, and gender of the respondent. This study also examined attributions of blame and attributions of motive (job‐related, ego, or love) to the romantic couple for engaging in the workplace romance. Results indicated that the team leader was more frequently attributed blame, yet attribution of blame was affected by the marital status of both the team leader and the coworker. Both the team leader and the coworker were most frequently attributed an ego motive for the involvement. Implications for work teams and managerial policies are discussed. Copyright © 1999 John Wiley & Sons, Ltd. 相似文献
199.
200.
Michelle T. Schärer Michael I. Nemeth Timothy J. Rowell Richard S. Appeldoorn 《Marine Biology》2014,161(1):141-147
Passive acoustic and synchronous video recordings were made at two spawning aggregation sites to study the sounds associated with reproductive behaviors of Mycteroperca bonaci. A characteristic sound was produced during courtship displays involving behaviors commonly observed for groupers of this genus at aggregations. The sound has a short pulsing section followed by a longer tonal portion with a mean peak frequency below 100 Hz. Courtship-associated sounds were quantified over one spawning season at Mona Island, Puerto Rico. Most of the daily sound production occurred during a period of 2 h prior to sunset. The highest rates of sound production lasted for a period of 10 days with lunar periodicity over three consecutive months coincident with the reported season of reproduction. Passive acoustics provide a tool to measure the variability of the reproductive activity of M. bonaci over time and may provide a method to evaluate current strategies designed to protect multi-species spawning aggregations that are critical for the recovery of threatened groupers. 相似文献