Survey on the pesticide residues in tea in south India

Tea is considered as a ‘health beverage’ due its antioxidant properties and resultant beneficial effects on human health. Such a beverage should be free from toxic elements such as pesticide residues and heavy metals. A large scale survey of teas produced in the tea factories of south India had been carried out for a period of three years from 2006 to 2008 and 912 tea samples were analysed for the residues of certain pesticides such as dicofol, ethion, quinalphos, hexaconazole, fenpropathrin, fenvalerate and propargite which are used for pest and disease control in tea in this part of the country. The analytical data proved that only less than 0.5 percentage of tea samples had residues of these pesticides. However, residues of pesticides were below their maximum limits in tea, stipulated by the European Union, Codex Alimentarius Commission of FAO/WHO and Prevention of Food Adulteration Act of Govt. of India.     

Modelling the long-term morphological evolution of the Clyde Estuary,Scotland, UK

The long-term morphodynamic response of the Clyde Estuary to any possible change in environmental forcing associated with global climate change and human interference is examined here using a model based on a systems approach. The model, which uses Boolean Algebra as its formal mathematical language, provides a qualitative insight into the long term morphodynamic behaviour of the estuarine system, at this level without the need for detailed and quantitative hydrodynamic and morphodynamic process knowledge or extensive data resources. The model predictions suggest that the long-term morphological changes in the Clyde Estuary largely depend on the fluvial flow of the River Clyde. Salt marshes in the upper reaches of the estuary were found to be the most vulnerable morphological feature of the estuary. In the event of increased river flow in the future, a likely situation according to climate change scenarios, saltmarshes will deplete or disappear altogether, irrespective of the sediment influx into the estuary. Changes to waves and tides will also contribute to the evolution by taking the estuary through significantly different intermediate morphological states whilst evolving towards a stable end state.     

Near-critical free-surface flows: real fluid flow analysis

An open channel flow with a flow depth close to the critical depth is characterised by a curvilinear streamline flow field that results in steady free surface undulations. Near critical flows of practical relevance encompass the undular hydraulic jump when the flow changes from supercritical (F > 1) to subcritical (F < 1), and the undular weir flow over broad-crested weirs where the flow changes from subcritical (F < 1) to supercritical (F > 1). So far these flows were mainly studied based on ideal fluid flow computations, for which the flow is assumed irrotational and, thus, shear forces are absent. While the approach is accurate for critical flow conditions (F = 1) in weir and flumes, near-critical flows involve long distances reaches, and the effect of friction on the flow properties cannot be neglected. In the present study the characteristics of near-critical free-surface flows are reanalysed based on a model accounting for both the streamline curvature and friction effects. Based on the improved model, some better agreement with experimental results is found, thereby highlighting the main frictional features of the flow profiles.     

Predator–prey models: an application for the plankton dynamics of lake Geneva

In this paper we present a hierarchical Bayesian analysis for a predator–prey model applied to ecology considering the use of Markov Chain Monte Carlo methods. We consider the introduction of a random effect in the model and the presence of a covariate vector. An application to ecology is considered using a data set related to the plankton dynamics of lake Geneva for the year 1990. We also discuss some aspects of discrimination of the proposed models.     

Confronting Management Challenges in Highly Uncertain Natural Resource Systems: a Robustness–Vulnerability Trade-off Approach

This paper presents a framework for the study of policy implementation in highly uncertain natural resource systems in which uncertainty cannot be characterized by probability distributions. We apply the framework to parametric uncertainty in the traditional Gordon–Schaefer model of a fishery to illustrate how performance can be sacrificed (traded-off) for reduced sensitivity and hence increased robustness, with respect to model parameter uncertainty. With sufficient data, our robustness–vulnerability analysis provides tools to discuss policy options. When less data are available, it can be used to inform the early stages of a learning process. Several key insights emerge from this analysis: (1) the classic optimal control policy can be very sensitive to parametric uncertainty, (2) even mild robustness properties are difficult to achieve for the simple Gordon–Schaefer model, and (3) achieving increased robustness with respect to some parameters (e.g., biological parameters) necessarily results in increased sensitivity (decreased robustness) with respect to other parameters (e.g., economic parameters). We thus illustrate fundamental robustness–vulnerability trade-offs and the limits to robust natural resource management. Finally, we use the framework to explore the effects of infrequent sampling and delays on policy performance.     

A Method for Ensemble Wildland Fire Simulation

An ensemble simulation system that accounts for uncertainty in long-range weather conditions and two-dimensional wildland fire spread is described. Fuel moisture is expressed based on the energy release component, a US fire danger rating index, and its variation throughout the fire season is modeled using time series analysis of historical weather data. This analysis is used to characterize the seasonal trend in ERC, autocorrelation of residuals, and daily standard deviation and stochastically generate artificial time series of afternoon fuel moisture. Daily wind speed and direction are sampled stochastically from joint probabilities of historical wind speed and direction for the date range of the fire simulation period. Hundreds or thousands of fire growth simulations are then performed using the synthetic fire weather sequences. The performance of these methods is evaluated in terms of the number of ensemble member simulations, one- versus two-dimensional fire spread simulations, and comparison with results from 91 fires occurring from 2007 to 2009. Simulations were found to be in consistent agreement with observations, but trends indicate that the ensemble average of simulated fire sizes were consistently larger than actual fires whereas the farthest extent burned by fires was underestimated.     

Numerical Simulations of Wind Induced Particle Contamination in Gypsum Landfill Surroundings

The contribution presents numerical simulation of gypsum particles, lifting from a gypsum landfill. First, particle characteristics are presented, resulting from different technologies of gypsum depositing. Next, a laboratory experiment parameter validation tests are described, which served as a means of determination of mass flow of particles from the landfill. The background of the numerical simulations, used in the assessment of landfill impact on the environment, is also described. Simulations consist of two parts: simulation of a long term impact of the particles on the surrounding area, performed by implementation of the Gaussian dispersion model based computer code ISC3, and second, a CFD based simulation for assessing the flow and mass concentration fields in the vicinity of the landfill for several pre-selected flow cases. The results of both computational approaches are presented and compared. In the conclusions, a relation of the simulation results with existing environmental pollution levels is made, and recommendations for landfill management are drawn.     

Hydraulics Analysis for Groundwater Flow Through Permeable Reactive Barriers

Groundwater flow modelling is an important tool in simulating and predicting hydraulic behaviour of groundwater transporting in the domain consisted of groundwater flow zone (aquifer) and permeable reactive barriers (PRBs). The aquifer regime is modelled using the Darcy equation, whereas PRBs are simulated by the Brinkman equation. By combining the above equations, the present paper is devoted to analyse the effect of permeability of aquifer (K _aq ) and reactive media (K _p ), groundwater flow velocity, and barrier size as well as assembled style of barriers on key barrier design parameter, such as the hydraulic capture zone width. The simulations indicate that the capture zone width generally decreases with a decrease in K _p at a given K _aq ; however, there is relatively little decrease in capture zone width when the K _p of freshly installed reactive media is roughly 10 times higher than the K _aq . For a given barrier system, the absolute capture zone width increases with an increase in barrier size, whereas the increment of relative capture zone width decreases dramatically. Although the capture zone width remains relatively unchanged as groundwater flow velocity increases, it results in a shorter residence time in the reactive media that may require greater barrier thickness so that contaminant levels can be reduced to regulatory limits. In addition, the effect of parallel barriers interaction on the capture zone width should be incorporated into the design. The present paper is based on the continuous reactive barrier and homogeneous barrier system. Similar methods can be used to analyse the hydrodynamics of funnel-and-gate system and heterogeneous settings by the appropriate modification.     

Optical fiber based methodology for assessment of thiocyanate in seawater

A new methodology for the assessment of thiocyanate (SCN(-)) is proposed based on optical fiber (OF) detection coupled to a liquid chromatography system (LC). The developed methodology showed an adequate performance for the analysis of SCN(-) comparable to a high performance liquid chromatography with UV detector (HPLC-UV) methodology: a detection limit of 3 μg L(-1), a linear range from 4 to 400 μg L(-1), and an analytical time of less than 6 min. The OF based methodology was of compact design and easy operation. This simple system has the potential to be used as a sensing approach for SCN(-) in seawater.     

Behaviour of different lichen species as biomonitors of air pollution by PAHs in natural ecosystems

Six different species of lichens (Parmelia sulcata Tayl., Evernia prunastri (L.) Ach., Ramalina farinacea, Pseudevernia furfuracea (L.) Zopf., Usnea sp. and Lobaria pulmonaria (Schreb.) Hoffm.) were collected in two mountain valleys in Central Pyrenees: the Aspe and Aragon valleys. Two multivariate techniques have been applied with different purposes, ANOVA and Discriminant Analysis (DA), to evaluate the data. The PAHs spatial distribution was studied in the three more abundant and widespread species in the area: P. sulcata, E. prunastri (L.) Ach. and R. farinacea in terms of total PAHs, PAHs related to the combustion processes and toxicity. Different behaviour of each lichen species to trap PAHs was found, being P. sulcata the best one to monitor the most persistent PAHs of pyrogenic origin and E. prunastri the most appropriate to provide information about pyrogenic and petrogenic PAHs. Traffic was the most relevant influence in PAHs bioaccumulation in lichen species.