首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
The models presented in this paper are motivated by a stop-over study of semipalmated sandpipers, Calidris pusilla. Two sets of data were collected at the stop-over site: a capture–recapture–resighting data set and a vector of counts of unmarked birds. The two data sets are analyzed simultaneously by combining a new model for the capture–recapture–resighting data set with a binomial likelihood for the counts. The aim of the analysis is to estimate the total number of birds that used the site and the average duration of stop-over. The combined analysis is shown to be highly efficient, even when just 1 % of birds are recaptured, and is recommended for similar investigations. This article has supplementary material online.  相似文献   

2.
A two-year field study (2003–2004 and 2004–2005) on the effects of four sulfur (S) levels (0, 15, 30, and 45 kg ha?1) in an onion–maize system revealed that S application in onion up to 30 kg ha?1 significantly increased fresh and dry bulb and foliage yield over the previous levels of 0 and 15 kg ha?1 (direct effect). In maize (residual effect) and onion–maize sequence as a whole (direct?+?residual effects), the same trend was visible. Sulfur additions beyond 30 kg ha?1 reduced the yields (economic yields as well as foliage/straw yields) of individual crops of onion, maize, and sequence (onion?+?maize) to the level of either 15 kg ha?1 or even the control. Sulfur-use efficiencies (kg yield kg?1 S) at S doses of 15, 30, and 45 kg ha?1, over no S, were 373, 303, and 109; 43, 63, and 2; and 413, 367, and 111 in onion, maize, and onion?+?maize, respectively. The utilizations of S added at three rates by onion, maize and onion?+?maize were 21.3, 16.7, and 9.1%; 2.0, 10.7, and –0.4%; and 23.3, 27.3 and 8.4%, respectively.  相似文献   

3.
Mao  Ting  Zhan Zhang  Ni  Shan-Jun  Zhao  Yi-Zhou  Li  Xin  Zhang  Li-Li  Liu  Yan  Li  Xu 《Genetic Resources and Crop Evolution》2021,68(5):1785-1797
Genetic Resources and Crop Evolution - Asian cultivated rice (Oryza sativa L.) is divided into two subspecies, indica (O. sativa L. subsp. indica) and japonica (O. sativa L. subsp. japonica)....  相似文献   

4.
5.
Abstract

Amending poultry litter with alum (aluminum sulfate) effectively reduces soluble phosphorus (P) concentrations, but the practice can be expensive. Aluminum (Al)‐based drinking‐water treatment residuals (WTRs) can be obtained free of charge and are enriched in Al hydr(oxides) that make them efficient P sorbents. Substituting Al‐WTRs for alum would be a cost‐effective practice to reduce soluble P in manures when compared with alum‐only use. The research studied the reductions in soluble P, Al, and total organic carbon (TOC) concentrations in suspensions prepared by mixing variable Al‐WTR and alum rates (0 to 25% by weight) with poultry litter. Suspensions were maintained at pH of 6.5 during the sorption step, and allowed to react up to 50 d, without shaking. On a per‐mole of oxalate‐extractable Al basis, the Al‐WTR was nearly as effective as alum in reducing P release. Increasing mixed alum/WTR mass loads resulted in greater soluble P reduction, simply due to increased molar Al/P ratios. Contact time did not significantly influence soluble P reduction. Two significant advantages of Al‐WTRs compared to alum indicated by this study are cost effectiveness and significantly less release of dissolved Al. Soluble Al and TOC concentrations were least for suspensions with the lowest soluble P levels, suggesting that P was removed from solution as an organo‐Al‐P amorphous phase. The amount of P desorbed from the mixtures decreased to <1% with increasing molar Al/P ratios ≥1. Results suggest that Al‐WTR application with or without alum can reduce soluble P in poultry litter; however, field validation of the amendment effectiveness is needed.  相似文献   

6.
The Cormack–Jolly–Seber (CJS) model assumes that all marked animals have equal recapture probabilities at each sampling occasion, but heterogeneity in capture often occurs and should be taken into account to avoid biases in parameter estimates. Although diagnostic tests are generally used to detect trap-dependence or transience and assess the overall fit of the model, heterogeneity in capture is not routinely tested for. In order to detect and identify this phenomenon in a CJS framework, we propose a test of positive association between previous and future encounters using Goodman–Kruskal’s gamma. This test is based solely on the raw capture histories and makes no assumption on model structure. The development of the test is motivated by a dataset of Sandwich terns (Thalasseus sandvicensis), and we use the test to formally show that they exhibit heterogeneity in capture. We use simulation to assess the performance of the test in the detection of heterogeneity in capture, compared to existing and corrected diagnostic goodness-of-fit tests, Leslie’s test of equal catchability and Carothers’ extension of the Leslie test. The test of positive association is easy to use and produces good results, demonstrating high power to detect heterogeneity in capture. We recommend using this new test prior to model fitting as the outcome will guide the model-building process and help draw more accurate biological conclusions. Supplementary materials accompanying this paper appear online.  相似文献   

7.
The direct estimation and modeling of population growth rate from capture–recapture data has now seen a number of applications. However, the original model cannot accommodate heterogeneous capture probabilities. While studying a population of small mammals Peromyscus maniculatus, we became concerned that the peak of population size may be estimated too late in the year because of heterogeneous catchability. Hence, we developed a variation of the original model with a finite number of catchability classes. The results obtained with the new model are more in agreement with the known biology of this population. A bibliographic appendix and computer code are available online.  相似文献   

8.
Experience in irrigation of chernozems in the steppe zone of Russia for a period from 1950 to 1990 is analyzed. By the end of this period and in the subsequent years, the areas under irrigation reduced considerably, and the soil productivity worsened. This was caused by the improper design of irrigation systems, on the one hand, and by the low tolerance of chernozems toward increased moistening upon irrigation, on the other hand. The analysis of the factors and regimes of soil formation under irrigation conditions shows that irrigation-induced changes in the soil hydrology also lead to changes in the soil physicochemical, biochemical, and other properties. In particular, changes in the composition of exchangeable cations lead to the development of solonetzic process. In many areas, irrigation of chernozems was accompanied by the appearance of solonetzic, vertic, saline, and eroded soils. The development of soil degradation processes is described. In general, the deterioration of irrigated chernozems was related to the absence of adequate experience in irrigation of steppe soils, unskilled personnel, improper regime of irrigation, and excessively high rates of watering. In some cases, the poor quality of irrigation water resulted in the development of soil salinization and alkalization. To improve the situation, the training of personnel is necessary; the strategy of continuous irrigation should be replaced by the strategy of supplementary irrigation in the critical periods of crop development.  相似文献   

9.
With the help of computed X-ray microtomography with a resolution of 2.75 μm, changes in the microstructure and pore space of aggregates of 3 mm in diameter from the virgin soddy-podzolic soil (Glossic Retisol (Loamic)) in the air-dry, capillary-moistened, and frozen states after five freeze–thaw cycles were studied in a laboratory experiment. The freezing of the samples was performed at their capillary moistening. It was shown that capillary moistening of initially air-dry samples from the humus (AY), eluvial (EL), and illuvial (BT1) horizons at room temperature resulted in the development of the platy, fine vesicular, and angular blocky microstructure, respectively. The total volume of tomographically visible pores >10 μm increased by 1.3, 2.2, and 3.4 times, respectively. After freeze–thaw cycles, frozen aggregates partly preserved the structural arrangement formed during the capillary moistening. At the same time, in the frozen aggregate from the AY horizon, the total tomographic porosity decreased to the initial level of the air-dry soil. In the frozen aggregate from the EL horizon, large vesicular pores were formed, owing to which the total pore volume retained its increased values. The resistance of aggregate shape to the action of freeze–thaw cycles differed. The aggregate from the EL horizon completely lost its original configuration by the end of the experiment. The aggregate from the AY horizon displayed definite features of sagging after five freeze–thaw cycles, whereas the aggregate from the BT1 horizon preserved its original configuration.  相似文献   

10.
The Fisher–Shannon information plane (FS), defined by the Fisher information measure and the Shannon entropy power, is proposed to investigate the complex dynamics of the concentration of three heavy metals (Cd, Fe, and Pb) in four different fractions of particulate matter data, recorded in Tito, a small industrial area of southern Italy. In the FS plane, the three metals are aggregated in three different clusters, characterized by different degrees of order. This result is related to different sources of the three metals.  相似文献   

11.
A method that utilizes solid-phase microextraction (SPME) coupled with gas chromatography (GC) and chemical ionization tandem mass spectrometry (MS/MS) was developed for analyzing a group of emerging pollutants, N-nitrosamines, in water. The developed analytical method requires a water sample of less than 5 ml and only 1.5 h for complete analysis. The method detection limits for N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine, and N-nitrosodi-n-propylamine were in the range of 3.2 to 3.5 ng/l; for N-nitrosomorpholine, it was 15.2 ng/l. The method was successfully employed to measure the N-nitrosamine concentration at trace levels of nanogram per liter in four water treatment plants (WTPs) and one water distribution system. In the WTPs, only NDMA was detected in the treatment processes. Within the treatment train, NDMA was observed after chlorination. The level of NDMA significantly declined after slow sand filtration due presumably to microbial degradation. The NDMA concentration collected from consumer tap water was about 40% higher on average than that in the finished water. The excellent performance of the SPME/GC/MS/MS method in various water matrices as well as the shorter analysis time and smaller sample volume compared to currently used extraction techniques makes it an alternative means for the analysis of N-nitrosamine in drinking water, wastewater, and laboratory research with small reactors.  相似文献   

12.
OBJECTIVE: To identify, using the novel application of multivariate classification trees, the socio-economic, sociodemographic and health-related lifestyle behaviour profile of adults who comply with the recommended 4 or more servings per day of fruit and vegetables. DESIGN: Cross-sectional 1998 Survey of Lifestyle, Attitudes and Nutrition. SETTING: Community-dwelling adults aged 18 years and over on the Republic of Ireland electoral register. SUBJECTS: Six thousand five hundred and thirty-nine (response rate 62%) adults responded to a self-administered postal questionnaire, including a semi-quantitative food-frequency questionnaire. RESULTS: The most important determining factor of compliance with the fruit and vegetable dietary recommendations was gender. A complex constellation of sociodemographic and socio-economic factors emerged for males whereas the important predictors of 4 or more servings of fruit and vegetable consumption among females were strongly socio-economic in nature. A separate algorithm was run to investigate the importance of health-related lifestyle and other dietary factors on compliance with the fruit and vegetable recommendations. Following an initial split on compliance with dairy recommendations, a combination of non-dietary behaviours showed a consistent pattern of healthier options more likely to lead to compliance with fruit and vegetable recommendations. There did, however, appear to be a compensatory element between the variables, particularly around smoking, suggesting the non-existence of an exclusive lifestyle for health risk. CONCLUSIONS: Material and structural influences matter very much for females in respect to compliance with fruit and vegetable recommendations. For males, while these factors are important they appear to be mediated through other more socially contextual-type factors. Recognition of the role that each of these factors plays in influencing dietary habits of men and women has implications for the manner in which dietary strategies and policies are developed and implemented.  相似文献   

13.
Bioindicators plants are important for the evaluation of air quality and Tillandsia usneoides L., an atmospheric epiphyte bromeliad, has been used for this purpose. The present study aims at evaluate the structural pattern of the leaf of this species when exposed to urban air pollutants, and determining whether the leaves present structural parameters that could be used as indicators of such pollutants. Samples of T. usneoides were exposed in São Paulo, the biggest city of Brazil, for 8, 16 and 24 weeks, and compared with others kept in a rural area. The urban pollution of São Paulo affected the structure of the leaves of T. usneoides causing alterations, especially in the scales, density of stomata and epidermis thickness. Qualitative alterations in the mesophyll were not observed in plants exposed at the polluted sites. These structural characteristics of T. usneoides seem to account for its high tolerance to heavy metal accumulation. The percentage of anomalous scales may potentially be used as an alternative bioindicator parameter.  相似文献   

14.
This article analyzes publication trends in food-borne disease research for the period 1991–2015, using data collected from the Web of Science Core Collection. A total of 11,725 research articles were used in the analysis. Results showed that the number of publications rose exponentially during the period of study. The average number of authors per article also increased. “Food Science & Technology” was the leading subject category under which the majority of articles placed. The Journal of Food Protection was the most productive journal with 794 articles. “Kang, DH” was the most productive author and the United States was the most productive country, followed by China.  相似文献   

15.
An ultrasonic method using two approaches, A and B, along with a reference Environmental Protection Agency (EPA) Method 3050B [i.e., a mixture of 30 mL of nitric acid–hydrochloric acid–hydrogen peroxide–water (HNO3-HCl-H2O2-H2O)] were contrasted for leaching of a plant matrix. The trace metals were arsenic, cadmium, cobalt, chromium, copper, mercury, manganese, nickel, lead, selenium, and zinc (As, Cd, Co, Cr, Cu, Hg, Mn, Ni, Pb, Se and Zn) and quantified by ICP-OES followed by an investigation into residue formation and the impact of digestion time. Approach B was the most accurate and precise with percent recoveries ranging between 99 and 120%, whereas ultrasonic approach A and the USEPA method 3050B gave similar results with poor accuracies and precisions. In the optimization of the digestion time using approach B, the total metal recovery was fairly the same over a period of 120 min except for Cr and Cu, which showed slight variations.  相似文献   

16.
In this study, a suitable and near-real-time water status monitoring approach for winter wheat before harvest was developed with remotely sensed satellite data. Seven vegetation indices were extracted as remote-sensing parameters by making full use of the land surface reflection and land surface temperature transmitted by moderate resolution imaging spectroradiometer (MODIS) data. The correlation of each vegetation index and measured values of winter wheat and soil water contents in different crop growth periods was established. The simulation models, combining vegetation index, soil water content (SWC), and plant water content (PWC) in different winter wheat growth periods, were constructed to predict water content by using remote-sensing data. We found that the correlations between the difference vegetation index (DVI) and the perpendicular vegetation index (PVI) in the beginning of the stem elongation period with SWC were highly significant (P < 0.01); the correlation between the global environmental monitoring index (GEMI) in the ear emergency period and SWC was highly significant (P < 0.01). Furthermore, the correlation between the PVI in maturing period and SWC was highly significant (P < 0.01). Data of different coefficients of vegetation indices and PWC in different winter wheat growth periods illustrated that correlation between the DVI in the beginning of stem elongation period and PWC was highly significant (P < 0.01), while the correlation between the PVI in the maturing period and PWC was highly significant. Our results indicated that spatial and temporal vegetation indices were closely related to soil moisture and winter wheat water content in Wenxi County, Shanxi Province (P. R. China). The vegetation index is conceptually and computationally straightforward and may be used in prediction of environmental hydrological status.  相似文献   

17.
Abstract

Arsenic (As) contamination is widespread in the industrial areas of northwest Ohio. Plant species that both take up As and are appropriate for the climate and growth conditions of the region are needed for phytoremediation to be successfully employed. Actively growing plants from 22 species of native genera were exposed to As in hydroponics systems (either 0, 10, or 50 mg As L?1; 1 week) and commercially available potting mix (either 0, 10, 25, 100, or 250 mg As L?1; 2 weeks), depending on their growth conditions. Aboveground plant tissues were harvested and digested, and concentrations of As were determined by inductively coupled plasma–optical emission spectrometry. The highest tissue concentrations of As (mg As kg?1 dw) were recorded in seven plant species: Rudbeckia hirta (661), Helenium autumnale (363 in tissues formed after exposure to As), Lupinus perennis (333), Echinacea purpurea (298), Coreopsis lanceolata (258), Lepidium virginicum (214), and Linum lewisii (214). These seven species are ecologically diverse, which suggests that phytoremediation of As using diverse assemblages of plants may be an option for a variety of environments.  相似文献   

18.
Abstract

The networks of 15 international research centers around the globe that are sponsored by the Consultative Group for International Agricultural Research (CGIAR) seeks to alleviate poverty in the developing world through enhanced production, while maintaining biodiversity and the sustainability of natural resources. The mandate of the International Center for Agricultural Research in the Dry Areas (ICARDA) is to focus on improving semi‐arid cropping systems in the drought‐prone West Asia and North Africa region. Since its inception in 1997, ICARDA's soil laboratory played a pivotal role in backstopping the institution's on‐station and on‐farm research in Syria and its collaborative research with the region's national programs. This article gives an overview of the evolution of soil and plant analysis in serving the center's mission. A major effort was the regional soil test calibration program, which set the basis for rational use of fertilizers and the identification of related nutrient constraints. Such analyses were extensively employed in all the long‐term dryland cropping system trials and later in irrigated agriculture and the interface between plant nutrition and crop breeding. Major emphasis was given to improving and upgrading analytical services in the region's laboratories. Despite advances made in analytical methodology, the challenge is to apply to solving real problems in the service of humanity.  相似文献   

19.
Urban rainfall–runoff residuals contain metals such as Cr, Zn, Cu, As, Pb and Cd and are thus reasonable candidates for treatment using Portland cement-based solidification–stabilization (S/S). This research is a study of S/S of urban storm water runoff solid residuals in Portland cement with quicklime and sodium bentonite additives. The solidified residuals were analyzed after 28 days of hydration time using X-ray powder diffraction (XRD) and solid-state 29Si nuclear magnetic resonance (NMR) spectroscopy. X-ray diffraction (XRD) results indicate that the main cement hydration products are ettringite, calcium hydroxide and hydrated calcium silicates. Zinc hydroxide and lead and zinc silicates are also present due to the reactions of the waste compounds with the cement and its hydration products. 29Si NMR analysis shows that the coarse fraction of the waste apparently does not interfere with cement hydration, but the fine fraction retards silica polymerization.  相似文献   

20.

Background, aim, and scope

The Mecklenburg Bight (Western Baltic Sea) near Luebeck, Germany was historically used to dump industrial waste at sea and, thus, sediments in some regions are highly polluted at present. While earlier studies identified hot spots of chemical pollution, little is known about biological activities and impacts on exposed marine organisms. This study aimed to assess the pollution in the Mecklenburg Bight to determine the degree of contamination with sediment-bound polycyclic aromatic hydrocarbons (PAHs) as well as biological activities.

Materials and methods

Sediment cores with a depth of 30 cm were sampled at a dumping site and at a reference site, sliced in distinct layers, freeze-dried, and processed using the accelerated solvent extraction method. Sediment was characterized measuring total organic carbon (TOC) and soot contents. Concentrations of the 16 EPA-PAHs were determined with chemical analysis (gas chromatography–mass spectroscopy) in each sediment slice and referred to the determined TOC content. Further on, in vitro biotests were applied to determine toxic effects of contaminants in the sediment. The acute neutral red retention assay indicated no specific cytotoxic effects. Arylhydrocarbon receptor (AhR)-mediated activities were measured using the mechanism-specific 7-ethoxyresorufin-O-deethylase induction assay. Both biotests were performed with rainbow trout (Oncorhynchus mykiss) liver cells (RTL-W1). Analyzed compound concentrations and biological activities were given in toxicological equivalent concentrations (chem- and bio-TEQs) to determine shares of analyzed EPA-PAHs to the overall activity.

Results

TOC and soot contents indicated a significant alteration through the sediment core at the dumping site. EPA-PAH concentrations were referred to TOC and indicated elevated concentrations at the dumping site. Maximum PAH concentrations (14 to 16 cm depth; 5.44 µg/g TOC) were 300-fold increased at the dumping site, compared to the reference site (4 to 6 cm depth; 0.017 µg/g TOC). Cytotoxicity as determined in the neutral red retention assay was elevated in some layers at the dumping site (maximum in 4 to 6 cm depth; NR50?=?14 mg/ml), but not correlated with TOC or soot contents. Ah receptor agonist activities were clearly elevated in highly PAH-loaded layers at both sites. At the dumping site, maximum activities were determined reflected by a bio-TEQ of 223,000 pg/g (19 to 22 cm), in contrast to a bio-TEQ of 41,000 pg/g (6 to 8 cm) at the reference site. Further on, shares of EPA-PAHs to the overall activity were determined and contributed >40% at the dumping site and between 4% and 17% at the reference site. Chem-TEQs were found to exceed bio-TEQs in a depth of 11 to 22 cm, indicating the presence of Ah receptor antagonistic or inhibitive compounds.

Discussion

Sediments from the dumping site were determined to be highly contaminated and caused toxic effects in depths that are known to be influenced by dumping activities. In contrast, the reference sediment indicated only near to surface layers to be minor contaminated. In comparison with highly polluted sediments from other marine sites, the contamination of the dumping site could be ranked as elevated. Chem-TEQs exceeding bio-TEQs in a depth of 11 to 22 cm seem to be caused by AhR antagonistic compounds in the dumped material. Furthermore, particle-bound PAH concentrations assessed in this study were discussed against freely dissolved concentrations in interstitial water, as determined in a different study with the same sediment core.

Conclusions

Sediments in the inner Mecklenburg Bight could be shown to be highly contaminated, at least with PAHs, causing articulate increased Ah receptor-mediated activities. Marine organisms may be exposed to these contaminants, in particular when inhabiting the sediment.

Recommendations and perspectives

Further research activities should extend the range of chemically analyzed pollutants and applied biotests and endpoints. Monitoring should close the gap between analytical methods in the laboratory and the field to determine possible impacts on organisms at site.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号