This paper mainly aims to study the linear element influence on the estimation of vascular plant species diversity in five Mediterranean landscapes modeled as land cover patch mosaics. These landscapes have several core habitats and a different set of linear elements -habitat edges or ecotones, roads or railways, rivers, streams and hedgerows on farm land- whose plant composition were examined. Secondly, it aims to check plant diversity estimation in Mediterranean landscapes using parametric and non-parametric procedures, with two indices: Species richness and Shannon index.Land cover types and landscape linear elements were identified from aerial photographs. Their spatial information was processed using GIS techniques. Field plots were selected using a stratified sampling design according to relieve and tree density of each habitat type. A 50×20 m2 multi-scale sampling plot was designed for the core habitats and across the main landscape linear elements. Richness and diversity of plant species were estimated by comparing the observed field data to ICE (Incidence-based Coverage Estimator) and ACE (Abundance-based Coverage Estimator) non-parametric estimators.The species density, percentage of unique species, and alpha diversity per plot were significantly higher (p < 0.05) in linear elements than in core habitats. ICE estimate of number of species was 32% higher than of ACE estimate, which did not differ significantly from the observed values. Accumulated species richness in core habitats together with linear elements, were significantly higher than those recorded only in the core habitats in all the landscapes. Conversely, Shannon diversity index did not show significant differences. 相似文献
The generation of reliable updated information is critical to support the harmonization of socio-economic and environmental
issues in a context of sustainable development. The agro-environmental assessment and management of agricultural systems often
relies on indicators that are necessary to make sound decisions. This work aims to provide an approach to (a) assess the environmental
performance of commercial farms in the Pampas of Argentina, and (b) propose a methodological framework to calculate environmental
indicators that can rapidly be applied to practical farming. 120 commercial farms scattered across the Pampas were analyzed
in this study during 2002 and 2003. Eleven basic indicators were identified and calculation methods described. Such indicators
were fossil energy (FE) use, FE use efficiency, nitrogen (N) balance, phosphorus (P) balance, N contamination risk, P contamination
risk, pesticide contamination risk, soil erosion risk, habitat intervention, changes in soil carbon stock, and balance of
greenhouse gases. A model named Agro-Eco-Index was developed on a Microsoft-Excel support to incorporate on-farm collected data and facilitate the calculation of indicators
by users. Different procedures were applied to validate the model and present the results to the users. Regression models
(based on linear and non-linear models) were used to validate the comparative performance of the study farms across the Pampas.
An environmental dashboard was provided to represent in a graphical way the behavior of farms. The method provides a tool
to discriminate environmentally friendly farms from those that do not pay enough attention to environmental issues. Our procedure
might be useful for implementing an ecological certification system to reward a good environmental behavior in society (e.g.,
through tax benefits) and generate a commercial advantage (e.g., through the allocation of green labels) for committed farmers. 相似文献
The structure and function of the coastal wetland ecosystem in the southern Laizhou Bay have been changed greatly and influenced by regional hydrological changes. The coastal wetlands have degraded significantly during the latest 30 years due to successive drought, decreasing of runoff, pollution, underground saline water intrusion, and aggravating marine disasters such as storm tides and sea level rising. Most archaic lakes have vanished, while artificial wetlands have been extending since natural coastal wetlands replaced by salt areas and ponds of shrimps and crabs. The pollution of sediments in inter-tidal wetlands and the pollution of water quality in sub-tidal wetlands are getting worse and therefore “red tides” happen more often than before. The biodiversity in the study area has been decreased. Further studies are still needed to protect the degraded coastal wetlands in the area. 相似文献
Non-point source (NPS) pollution is the result of various land use practices such as agriculture, sites of construction and
waste disposal, urban development and so on. The control of NPS pollution is possible by regular monitoring and assessment
on watershed basis to educate people for implementing well-known structural and non-structural measures. Recent trend is to
use GIS based modelling tool for assessment of rainfall-runoff and non-point loading. The approach requires generation and
analysis of basin wide data on various features of land and estimates of Event Mean Concentrations (EMCs) of pollutants in
the runoff. In the present paper, basin wide data in different districts of Tapi basin has been analysed for land use distribution;
fertilizer application; low, medium and high-density habitation; and annual rainfall. Coefficients of runoff have been estimated
considering pervious and impervious area for different land use types, and compared with the reported values for Indian conditions.
The estimated mean annual runoff flow indicated that two districts Jalgaon and Dhule contribute maximum runoff to the Tapi
River. Estimates of EMCs for BOD and nutrients (N and P) in the runoff from various districts are useful in GIS-based modelling
study for NPS pollution assessment. 相似文献
To investigate the effect of temperature on effective diffusion coefficients and retardation factors for Zn and Cd, combined
diffusion and sequential extraction analyses were conducted at 15 ˚C and 55 ˚C. The effective diffusion coefficients of the metals increased up to ten times according to the increased temperature. On
the other hand, the effect of temperature on the retardation factor depended on the retention mechanisms of the metals. The
distribution coefficient for Zn, which was mainly partitioned in the carbonate phase, increased up to two times with the increase
in temperature. On the other hand, the distribution coefficient for Cd, which was mainly partitioned in the exchangeable phase,
was hardly affected by the temperature change. Results of combined diffusion and sequential extraction analysis showed that
the effect of temperature on the heavy metals’ (Zn and Cd) migration through the compacted natural clay was influenced by
the combined effects of the diffusion coefficient and the retardation factor. Additionally, we could also observe the change
in retention mechanism for the metals with the change in pore water concentration. 相似文献
Nitrate contamination of water sources is a concern where large amounts of nitrogen fertilizers are regularly applied to soils.
Ingested nitrate from dietary sources and drinking water can be converted to nitrite and ultimately to N-nitroso compounds,
many of which are known carcinogens. Epidemiologic studies of drinking water nitrate and cancer report mixed findings; a criticism
is the use of nitrate concentrations from retrospective drinking water data to assign exposure levels. Residential point-of-use
nitrate data are scarce; gaps in historical data for municipal supply finished water hamper exposure classification efforts.
We used generalized linear regression models to estimate and compare historical raw water and finished water nitrate levels
(1960s--1990s) in single source Iowa municipal supplies to determine whether raw water monitoring data could supplement finished
water data to improve exposure assessment. Comparison of raw water and finished water samples (same sampling date) showed
a significant difference in nitrate levels in municipalities using rivers; municipalities using other surface water or alluvial
groundwater had no difference in nitrate levels. A regional aggregation of alluvial groundwater municipalities was constructed
based on results from a previous study showing regional differences in nitrate contamination of private wells; results from
this analysis were mixed, dependent upon region and decade. These analyses demonstrate using historical raw water nitrate
monitoring data to supplement finished water data for exposure assessment is appropriate for individual Iowa municipal supplies
using alluvial groundwater, lakes or reservoirs. Using alluvial raw water data on a regional basis is dependent on region
and decade. 相似文献
Food crops such as cassava, cocoyam and other tuber crops grown in mining communities uptake toxic or hazardous chemicals
such as arsenic, and cadmium, from the soil. Cassava is a stable food for Ghanaians. This study evaluated human health risk
from eating cassava grown in some mining communities in Ghana such as Bogoso, Prestea, Tarkwa and Tamso, which are important
mining towns in the Western Region of Ghana. The study evaluated cancer and non-cancer health effects from eating cassava
grown in the study areas in accordance with US Environmental Protection Agency’s Risk Assessment guidelines. The results of
the study revealed the following: cancer health risk for Tamso, 0.098 (RME – Reasonable Maximum Exposure) and 0.082 (CTE –
Central Tendency Exposure). This means that approximately 10 and 8 out of 100 resident adults are likely to suffer from cancer
related cases by RME and CTE parameters respectively. For Prestea, we have 0.010 and 0.12, which also means that approximately
1 out of 100 and 10 resident adults out of 100 are also likely to suffer from cancer related diseases by RME and CTE parameters.
The results of the study obtained were found to be above the acceptable cancer risk range of 1× 10−6 to 1× 10−4, i.e., 1 case of cancer out of 1 million or 100,000 people respectively. 相似文献
Objective: Intersection movement assist (IMA) has been recognized as one of the prominent countermeasures to reduce angle crashes at intersections, which constitute 22% of total crashes in the United States. Utilizing vehicle-based sensors, vehicle-to-vehicle (V2V), and vehicle-to-infrastructure (V2I) communications, IMA offers extended vision to provide early warning for an imminent crash. However, most of IMA-related research implements their methods and strategies only in simulations, test tracks, or driving simulator studies that have quite a few assumptions and limitations and hence the effectiveness evaluations reported may not be transferable or comparable.
Methods: This study seeks to develop a generalized evaluation scheme that can be used not only to assess the effectiveness of IMA on improving traffic safety at intersections but to facilitate comparisons across similar studies. The proposed evaluation scheme utilizes the concepts of traffic conflict in terms of time-to-collision (TTC) as a crash surrogate. This approach avoids the issue of having insufficient crash frequency data for system evaluation. To measure the effectiveness of IMA on reducing traffic conflicts, a relative risk is calculated for comparing the risk of with/without using the IMA. As a proof-of-concept study, this study applied the proposed evaluation scheme and reported the effectiveness of IMA on improving traffic safety in a field operation test (FOT). Seven test scenarios were conducted at 4 intersections, and a total of 40 participants were recruited to use the IMA for 6 months.
Results: It was estimated that IMA users have 26% fewer conflicts with TTC less than 5 s and have 15% fewer conflicts with TTC less than 4 s. However, the results vary across different sites and different definitions of conflicts in terms of TTC.
Conclusions: Overall, IMA is promising to effectively reduce angle crashes related to sight obstruction and has potential to reduce not only crash frequency but crash severity. 相似文献
Objective: The overrepresentation of young drivers in poor road safety outcomes has long been recognized as a global road safety issue. In addition, the overrepresentation of males in crash statistics has been recognized as a pervasive young driver problem. Though progress in road safety evidenced as a stabilization and/or reduction in poor road safety outcomes has been made in developed nations, less-developed nations contribute the greatest road safety trauma, and developing nations such as Colombia continue to experience increasing trends in fatality rates. The aim of the research was to explore sex differences in self-reported risky driving behaviors of young drivers, including the associations with crash involvement, in a sample of young drivers attending university in Colombia.
Methods: The Spanish version of the Behaviour of Young Novice Drivers Scale (BYNDS-Sp) was applied in an online survey to a sample of 392 students (225 males) aged 16–24 years attending a major university. Appropriate comparative statistics and logistic regression modeling were used when analyzing the data.
Results: Males reported consistently more risky driving behaviors, with approximately one quarter of all participants reporting risky driving exposure. Males reported greater crash involvement, with violations such as speeding associated with crash involvement for both males and females.
Conclusion: Young drivers in Colombia appear to engage in the same risky driving behaviors as young drivers in developed nations. In addition, young male drivers in Colombia reported greater engagement in risky driving behaviors than young female drivers, a finding consistent with the behaviors of young male drivers in developed nations. As such, the research findings suggest that general interventions such as education, engineering, and enforcement should target transient rule violations such as speeding and using a handheld mobile phone while driving for young drivers in Colombia. Future research should investigate how these interventions could be tailored specifically for the Colombian cultural context, including how their effects can be evaluated, prior to implementation. 相似文献
Objective: The objective of this article was the construction of injury risk functions (IRFs) for front row occupants in oblique frontal crashes and a comparison to IRF of nonoblique frontal crashes from the same data set.
Method: Crashes of modern vehicles from GIDAS (German In-Depth Accident Study) were used as the basis for the construction of a logistic injury risk model. Static deformation, measured via displaced voxels on the postcrash vehicles, was used to calculate the energy dissipated in the crash. This measure of accident severity was termed objective equivalent speed (oEES) because it does not depend on the accident reconstruction and thus eliminates reconstruction biases like impact direction and vehicle model year. Imputation from property damage cases was used to describe underrepresented low-severity crashes―a known shortcoming of GIDAS. Binary logistic regression was used to relate the stimuli (oEES) to the binary outcome variable (injured or not injured).
Results: IRFs for the oblique frontal impact and nonoblique frontal impact were computed for the Maximum Abbreviated Injury Scale (MAIS) 2+ and 3+ levels for adults (18–64 years). For a given stimulus, the probability of injury for a belted driver was higher in oblique crashes than in nonoblique frontal crashes. For the 25% injury risk at MAIS 2+ level, the corresponding stimulus for oblique crashes was 40 km/h but it was 64 km/h for nonoblique frontal crashes.
Conclusions: The risk of obtaining MAIS 2+ injuries is significantly higher in oblique crashes than in nonoblique crashes. In the real world, most MAIS 2+ injuries occur in an oEES range from 30 to 60 km/h. 相似文献