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.
Accumulation of Cu and Cd by Vallisneria spiralis was studied under laboratory conditions. Plants showed ability to reduce 5 µg ml–1 Cu background concentration to below 0.05 µg ml–1 (m.p.l., WHO 1985) within 48 h. The Cd concentration of 1.0 µg ml–1 was reduced to below m.p.l. (0.005 µg ml–1) in 168 h. Cysteine synthesis was more under Cd stress condition. Both the metals were toxic to the plants at higher concentrations; more in the case of Cd.NBRI Rsearch Publication No. 417 (N.S.).  相似文献   

2.
The aim of the present work was to monitor the Hg pollution in water and sediments of G.B. Pant Sagar located in Singrauli Industrial Region, India and to suggest the efficient aquatic plants for its phytoremediation. The study assessed the comparative potential of a free floating water fern Azolla pinnata and submerged aquatic macrophyte Vallisneria spiralis to purify waters polluted by Hg. Six days laboratory experiments have been conducted to mark the percentage removal of Hg at initial concentration of 0.1, 0.5, 1.0 and 3.0 mg L(-1). The percentage removal of Hg was higher for A. pinnata (80-94%) than V. spiralis (70-84%). Likewise, the Hg accumulated in dry mass was much higher for A. pinnata and a high correlation (R(2) = 0.91 for A. pinnata and 0.99 for V. spiralis) was obtained between applied Hg doses and accumulated amounts in biomass. A concentration dependent decrease in chlorophyll a, protein, RNA, DNA and nutrients (NO(3-) and PO(4)(3-)) uptake was detected in A. pinnata and V. spiralis due to Hg toxicity. The decrease was more prominent in Azolla than Vallisneria. The results recommended the use of A. pinnata and V. spiralis to ameliorate the industrial effluents (thermal power, chlor-alkali and coal mine effluent) contaminated with Hg.  相似文献   

3.
本文以"十三五"环境统计数据及巴音郭楞蒙古自治州统计年鉴为数据源分析了巴州污染源时空变化及污染物排放强度,总结出污染物排放主要受社会经济生产、能源消耗、产业发展及环境保护政策等综合因素影响,并提出了建议以期政策实施促进巴州环境经济可持续发展.  相似文献   

4.
The increasing incidence of toxic cyanobacterial blooms, together with the difficulties to reliably predict cyanobacterial toxin (e.g. microcystins) concentration, has created the need to assess the predictive ability and variability of the cyanobacterial biomass–microcystin relationship, which is currently used to assess the risk to human and ecosystems health. To achieve this aim, we assessed the relationship between cyanobacterial biomass and microcystin concentration on a spatiotemporal scale by quantifying the concentration of cyanobacterial biomass and microcystin in eight lakes over 9 months. On both a temporal and spatial scale, the variability of microcystin concentration exceeded that of cyanobacterial biomass by up to four times. The relationship between cyanobacterial biomass and microcystin was weak and site specific. The variability of cyanobacterial biomass only explained 25 % of the variability in total microcystin concentration and 7 % of the variability of cellular microcystin concentration. Although a significant correlation does not always imply real cause, the results of multiple linear regression analysis suggest that the variability of cyanobacterial biomass and cellular microcystin concentration is influenced by salinity and total phosphorus, respectively. The weak cyanobacterial biomass–microcystin relationship, coupled with the fact that microcystin was present in concentrations exceeding the WHO drinking water guidelines (1 μg?L?1) in most of the collected samples, emphasizes the high risk of error connected to the traditional indirect microcystin risk assessment method.  相似文献   

5.
The water reservoir of Vargem das Flores, Brazil, has been subject to eutrophication problems. The occurrence of cyanobacterial blooms in this water body has raised concerns regarding the presence of toxic metabolites. In order to understand the factors that promote the proliferation and distribution of cyanobacteria in the reservoir, physicochemical parameters, species composition, and toxicity of the reservoir water column were analyzed at monthly intervals over a 3-year period (2004-2007) using a range of analytical techniques. The results showed that cyanobacteria were absent in the dry period, returning after the onset of stratification. A succession pattern was observed within this group. The Aphanocapsa genus was dominant in the last rainy period of the study (October 2006 to March 2007). However toxicity was only detected when the genera Microcystis and Sphaerocavum were present (October 2005). The principal components analysis showed negative correlation between cyanobacteria and orthophosphate. The change of dominant cyanobacteria along the 3 years of study and the final prevalence of nontoxic genera in the reservoir is an evidence of water quality improvement in response to the management techniques implemented in the reservoir basin.  相似文献   

6.
在两年半期间内 ,对污染程度不同的两地进行了 5次青春期前期儿童 (7~ 1 2岁 ) 4 57例肺功能 (FVC,FEV1 ,PEFR,FEF2 5~ 75 )生长速率的观测及生长状况的比较分析得出 ,两地儿童身高和体重的生长曲线无明显差异 ,而肺功能的生长速率则有明显的差异 ,勿论男女、同年龄的儿童肺功能增长速率污染区要低于对照区  相似文献   

7.
The main goal of this study is to determine the present heavy metal pollution state in the two gulfs of the Aegean Sea; Saros and Gökova Gulfs. The surface sediments were collected from 11 and eight locations in the Saros and Gökova during May 2001, respectively. The results showed that the sediments of Saros and Gökova gulfs were polluted with Pb, Cr, Zn, Mn, and Ni and Pb, Cr, Ni, and Mn, respectively. For various metals the contamination factor (CF) has been calculated to assess the degree of pollution in sediments. The sediments were noted to be not contaminated with Hg, Cd, and Cu in all areas. Moderate contaminations were observed for Pb, Cr, and Zn in Saros Gulf. The CF was moderate and very high for Ni in the Saros and the Gökova Gulf, respectively.  相似文献   

8.
The environment is very important in terms of the behaviours and actions of human beings, and activity–environment correlation is used frequently in outdoor arrangements. The environment must meet the requirements and expectations of society. Outdoor activities are the activities that contribute to the well-being of human beings in physical (heartbeat, respiration, blood pressure, etc.) (Ulrich, Journal of Environmental Psychology 11:210–230, 1991), psychological (fear, anxiety, depression, loneliness, stress, etc.) (Marcus and Barnes 1999) and behavioural (insomnia, nervousness, restlessness, passivity, etc.) (Ulrich 1999) terms. It is known that human beings are affected significantly by the environments they are in, and more importantly, it is known that the environment they are in affects their happiness status. The causes of this effect are the features and appearances of the spatial elements and components that mainly make up such environments. One of the elements that is used frequently in landscape is water. If one examines designed or natural open spaces, it may be observed that water has very distinctive features. Dynamic (in the form of a leak, with intense flow rate, cascade, foamy, squirting, jet, graded, etc.) and still water elements may be used with sculptures, plants, rocks and elevations (on land). This study aims to reveal which age groups of students enjoy the different types of activities with regards to water features and emotional associations that motion and characteristics of water bring out in human beings and also to reveal the water preferences of human beings, including their reasons for such preference. Thus, 20 different water compositions located in Edirne Province were selected, and in 2-min camera reels, the students of various age groups assessed water with various characteristic features via a survey. As a result, it was revealed that human beings from various age groups wish to perform different activities with water elements having distinctive characteristic features, and the types of water elements that are subject to various age groups’ like and dislike were determined. Kruskal–Wallis test was used during testing the effect of age differences. Chi-square analysis was used in order to examine the effect of age differences on preferences with regards to the activities that shall be performed at locations that include utilization of various water elements. The results reveal that while the use of water should be allowed in landscaping, selections regarding the elements of these water features should be made based on the type of activity and the age group of users in relation to the location.  相似文献   

9.
Remote sensing of local environmental conditions is not accessible if substrates are covered with vegetation. This study explored the relationship between vegetation spectra and karst eco-geo-environmental conditions. Hyperspectral remote sensing techniques showed that there were significant differences between spectral features of vegetation mainly distributed in karst and non-karst regions, and combination of 1,300- to 2,500-nm reflectance and 400- to 680-nm first-derivative spectra could delineate karst and non-karst vegetation groups. Canonical correspondence analysis (CCA) successfully assessed to what extent the variation of vegetation spectral features can be explained by associated eco-geo-environmental variables, and it was found that soil moisture and calcium carbonate contents had the most significant effects on vegetation spectral features in karst region. Our study indicates that vegetation spectra is tightly linked to eco-geo-environmental conditions and CCA is an effective means of studying the relationship between vegetation spectral features and eco-geo-environmental variables. Employing a combination of spectral and spatial analysis, it is anticipated that hyperspectral imagery can be used in interpreting or mapping eco-geo-environmental conditions covered with vegetation in karst region.  相似文献   

10.
Atmospheric corrections for multi-temporal optical satellite images are necessary, especially in change detection analyses, such as normalized difference vegetation index (NDVI) rationing. Abrupt change detection analysis using remote-sensing techniques requires radiometric congruity and atmospheric correction to monitor terrestrial surfaces over time. Two atmospheric correction methods were used for this study: relative radiometric normalization and the simplified method for atmospheric correction (SMAC) in the solar spectrum. A multi-temporal data set consisting of two sets of Landsat images from the period between 1991 and 2002 of Penang Island, Malaysia, was used to compare NDVI maps, which were generated using the proposed atmospheric correction methods. Land surface temperature (LST) was retrieved using ATCOR3_T in PCI Geomatica 10.1 image processing software. Linear regression analysis was utilized to analyze the relationship between NDVI and LST. This study reveals that both of the proposed atmospheric correction methods yielded high accuracy through examination of the linear correlation coefficients. To check for the accuracy of the equation obtained through linear regression analysis for every single satellite image, 20 points were randomly chosen. The results showed that the SMAC method yielded a constant value (in terms of error) to predict the NDVI value from linear regression analysis-derived equation. The errors (average) from both proposed atmospheric correction methods were less than 10%.  相似文献   

11.
This paper intended to examine the seasonal variations in the relationship between landscape pattern and land surface temperature based on a case study of Indianapolis, United States. The integration of remote sensing, GIS, and landscape ecology methods was used in this study. Four Terra's ASTER images were used to derive the landscape patterns and land surface temperatures (LST) in four seasons in the study area. The spatial and ecological characteristics of landscape patterns and LSTs were examined by the use of landscape metrics. The impact of each land use and land cover type on LST was analyzed based on the measurements of landscape metrics. The results show that the landscape and LST patterns in the winter were unique. The rest of three seasons apparently had more agreeable landscape and LST patterns. The spatial configuration of each LST zone conformed to that of each land use and land cover type with more than 50% of overlap in area for all seasons. This paper may provide useful information for urban planers and environmental managers for assessing and monitoring urban thermal environments as result of urbanization.  相似文献   

12.
工业废水BOD5与CODCr相关关系以及BOD5测定的简化法   总被引:1,自引:0,他引:1  
通过研究BOD5与CODCr的相关性,用线性函数BOD5=a+bCODCr的形式进行一元回归,间接求出BOD5或指导BOD5的测定,验证BOD5结果的准确性以及通过对稀释法公式的推导得出简化法的公式,并与稀释法进行比较,结果表明,简化后的方法与稀释法无显著差异,精密度、准确度较好。  相似文献   

13.
14.
Acid volatile sulfide (AVS) has been regarded as an important factor controlling metal bioavailability in anoxic sediments, but its effect on metal accumulation under natural conditions is poorly understood. Here, a field study of the influence of AVS on metal accumulation by Limnodrilus sp. in a heavily polluted river is provided. Most of the study area was subject to anaerobic and strongly reducing conditions, and the concentration of trace metals in surface sediments was high, as were the concentration of AVS and simultaneously extracted metals (SEM; average AVS?=?20.3 μmol g?1, average ∑SEM5?=?9.42 μmol g?1; ∑SEM5 refers to the sum of SEMCd, SEMCu, SEMPb, SEMNi, and SEMZn). Only a few species and small quantities of benthic invertebrates were found, and Limnodrilus sp. was dominant. There was no correlation between trace metal accumulation and (SEM-AVS), and in stations where (SEM-AVS) <0, the absolute value of bioaccumulation was high (average ∑BIO5?=?4.07 μmol g?1; ∑BIO5 refers to the sum of BIOCd, BIOCu, BIOPb, BIONi, and BIOZn), indicating that there was no relationship between (SEM–AVS) and metal accumulation in Limnodrilus sp. This was likely because Limnodrilus sp. ingest sediment particles as their main food source, so pore water metals play a minor role in their bioaccumulation (BIO) of materials. However, ∑BIO5 was significantly correlated with ∑SEM5 (r?=?0.795, p?<?0.01), revealing that the large number of sulfide-bound metals (SEM) in sediments may play an important role in metal accumulation in Limnodrilus sp., which can assimilate sulfide-associated metals by the help of the digestive fluids in the digestive systems.  相似文献   

15.
Two statistical tests for correlation between a circular variate and a linear variate are presented. The tests are applied to a small data set concerning Freon-12 concentration and wind direction in Woods Hole, Massachusetts during the summer of 1987. A significant correlation is found. Further analysis suggests that this directional effect is related to onshore Freon-12 release.Woods Hole Oceanographic Institution Contribution Number 6750  相似文献   

16.
Southern Ontario receives the highest levels of atmospheric nitrogen (N) deposition in Canada and there are concerns that forests in the region may be approaching a state of ‘N saturation’. In order to evaluate whether potential chemical indices provide evidence of N saturation, 23 hardwood plots were sampled along a modeled N-deposition gradient ranging from 9.3 to 12.8 kg/ha/year. All plots were dominated by sugar maple (Acer saccharum Marsh.) and foliar N and foliar δ15N were positively correlated with modeled N deposition. However, forest floor N content and the C:N ratio were unrelated to N deposition, but were instead related to soil pH and annual temperature; lower C:N ratios and higher N content in the forest floor were found at the most acidic sites in the cooler, northern part of the study region despite lower N deposition. Likewise, δ15N values in surface mineral soil and the 15N enrichment factor of foliage (δ15N foliage ? δ15N soil) are correlated to soil pH and temperature and not N deposition. Further, potential N mineralization, ammonification, and nitrification in Ontario maple stands were highest in the northern part of the region with the lowest modeled N deposition. Nitrogen cycling in soil appears to be primarily influenced by the N status of the forest floor and other soil properties rather than N deposition, indicating that chemical indices in soil in these hardwood plots may not provide an early indicator of N saturation.  相似文献   

17.
In present study, we measured the activities of some selected cytochrome P450 isozymes like ethoxyresorufin-o-deethylase (EROD), pentoxyresorufin-o-deethylase (PROD), and N-nitrosodimethylamine demethylase (NDMA-d) treating experimental rats with different environmental toxicants, namely trichloroethylene (TCE), heavy metal mixture, and ethyl alcohol individually or in combination and by exposing the Allium cepa bulbs to increasing concentration of TCE for 48 h. In animal system, NDMA-d activity displayed a remarkable amplification by 4.2-fold in the liver of alcohol ingested rats compared with control animals. TCE intake also resulted in a marked increase of around 3.8-fold and 1.2-fold in rats’ NDMA-d activity in the liver and kidney, respectively. In onion bulbs, an amazing rise in the activity of test enzymes was recorded in a dose-dependent manner. Among the said enzymes, PROD showed maximum increase up to the extent of 22-fold in comparison with control at 20 ppm of TCE exposure, whereas NDMA-d and EROD showed 11- and 9-fold increase in enzymatic activity, respectively, compared with the control. Based on this study, we conclude and advocate that all the selected isozymes of CYP450 system, viz. PROD, NDMA-d, and EROD can act as potent biomarkers in plant system for assessing the TCE pollution.  相似文献   

18.
We examined the relationship between muscle and scale mercury (Hg) and lead (Pb) concentrations in chub Squalius cephalus L. from six riverine sites in the Czech Republic in order to determine whether scale analysis alone could provide a nonlethal and convenient method for prediction of heavy metal concentration in muscle tissue. Our results confirm tissue-specific heavy metal accumulation in chub, with Hg tending to accumulate primarily in muscle tissue and Pb in scales. We found no significant relationship, however, for concentrations of either Pb or Hg between muscle tissue and scales of chub. Our results indicate that scales cannot be used for predicting heavy metal contamination in muscle of chub and we recommend, therefore, that muscle biopsy methods continue as the preferred method of analysis.  相似文献   

19.
Thematic mapping of complex landscapes, with various phenological patterns from satellite imagery, is a particularly challenging task. However, supplementary information, such as multitemporal data and/or land surface temperature (LST), has the potential to improve the land cover classification accuracy and efficiency. In this paper, in order to map land covers, we evaluated the potential of multitemporal Landsat 8’s spectral and thermal imageries using a random forest (RF) classifier. We used a grid search approach based on the out-of-bag (OOB) estimate of error to optimize the RF parameters. Four different scenarios were considered in this research: (1) RF classification of multitemporal spectral images, (2) RF classification of multitemporal LST images, (3) RF classification of all multitemporal LST and spectral images, and (4) RF classification of selected important or optimum features. The study area in this research was Naghadeh city and its surrounding region, located in West Azerbaijan Province, northwest of Iran. The overall accuracies of first, second, third, and fourth scenarios were equal to 86.48, 82.26, 90.63, and 91.82 %, respectively. The quantitative assessments of the results demonstrated that the most important or optimum features increase the class separability, while the spectral and thermal features produced a more moderate increase in the land cover mapping accuracy. In addition, the contribution of the multitemporal thermal information led to a considerable increase in the user and producer accuracies of classes with a rapid temporal change behavior, such as crops and vegetation.  相似文献   

20.
Mentougou District acts as a crucial component in the ecological buffer in western Beijing mountainous areas, Beijing, China. Using two Landsat MSS/TM images acquired on July 14, 1979 and July 23, 2005, the vegetation coverage of Mentougou District was calculated based on normalized difference vegetation index and spectral mixture analysis (NDVI-SMA) model. Its temporal and spatial changes were analyzed according to digital elevation model (DEM) image, social and economic data. The results showed that the vegetation coverage decreased from 76.4% in 1979 to 72.7% in 2005. Vegetation degradation was probably the result of human disturbance, such as outspreading of resident areas, and coal and stone mining activities, while vegetation restoration might be contributed by the combined effects of both natural processes and ecological construction effort. Vegetation changes were closely related to topographical characteristics. Plants at high altitude were more stable and less degraded than the plants at low altitude, while the plants on steep slope or northwest aspect were more vulnerable to degradation. During the period of 26 years, landscape appeared to become more fragmental, and ecological quality of the land seemed deteriorated sharply in that highly-covered vegetation area has been decreased by 24%.  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