A comparison of numerical solutions of partial differential equations with probabilistic and possibilistic parameters for the quantification of uncertainty in subsurface solute transport

Traditionally, uncertainty in parameters are represented as probabilistic distributions and incorporated into groundwater flow and contaminant transport models. With the advent of newer uncertainty theories, it is now understood that stochastic methods cannot properly represent non random uncertainties. In the groundwater flow and contaminant transport equations, uncertainty in some parameters may be random, whereas those of others may be non random. The objective of this paper is to develop a fuzzy-stochastic partial differential equation (FSPDE) model to simulate conditions where both random and non random uncertainties are involved in groundwater flow and solute transport. Three potential solution techniques namely, (a) transforming a probability distribution to a possibility distribution (Method I) then a FSPDE becomes a fuzzy partial differential equation (FPDE), (b) transforming a possibility distribution to a probability distribution (Method II) and then a FSPDE becomes a stochastic partial differential equation (SPDE), and (c) the combination of Monte Carlo methods and FPDE solution techniques (Method III) are proposed and compared. The effects of these three methods on the predictive results are investigated by using two case studies. The results show that the predictions obtained from Method II is a specific case of that got from Method I. When an exact probabilistic result is needed, Method II is suggested. As the loss or gain of information during a probability–possibility (or vice versa) transformation cannot be quantified, their influences on the predictive results is not known. Thus, Method III should probably be preferred for risk assessments.     

Development of a landfill model to prioritize design and operating objectives

The application of scientifically based decision making tools to help address solid waste management issues dates back to the early 1960s. Researchers continue to use operations research tools to help optimize landfill design and operating parameters. This paper discusses the application of another type of decision making tool, the analytical hierarchy process (AHP), to address priority ranking for a number of landfill engineering design and operating objectives in developing and developed countries. In this application, the AHP is used to rank, and prioritize, economic, environmental, health and safety, legislative and public perception objectives for landfill design and operations specific to landfill distance from a community, and precipitation levels. Results from a global survey using the Delphi process are included, with a discussion on the survey’s impact on the objective rankings relative to community proximity and precipitation. The Delphi process worked extremely well, and was an excellent tool to use in this application. The initial results from the objective rankings show promise in the development of an integrated model for landfill design and operation.     

A Numerical Model Simulating the Remediation of Hydrocarbon-Impacted Soils Using Low-Temperature Oxidation

A 2-D mathematical model to simulate the temperature distribution, coke formation, and change in residual extractable oil during remediation by low-temperature oxidation (LTO) process was developed. Simulation results indicate that the spacing between wells, pressure difference, and air-injection temperature and different well patterns influence the temperature distribution and consequently the level of remediation in the soil. The model results for coke formation and residual extractable oil distribution compared well with experimental results. The operating conditions—air-injection temperature of about 200°C, air-injection pressure of 6 to 10 kPa, air-extraction pressure of −110 Pa, and wells spaced 1 m apart installed in a nine-spot pattern—provide good remediation of hydrocarbons in soil by LTO process.

Is rainfall gradient a factor of livelihood diversification? Empirical evidence from around climatic hotspots in Indo-Gangetic Plains

Farmers in the Indo-Gangetic Plains are constantly seeking ways to adapt to changing circumstances and opportunities that include new technologies, institutions, policies, socio-economic and cultural shifts, as well as a changing climate. The relationship between rainfall and local livelihoods is important to devise policies to improve adaptive capacity of farmers to different drivers of changes. The present study investigates whether the spatial variations in rainfall have prompted the location-specific livelihood diversification by using data from 2660 farm families in the climatic risk areas in India, Nepal and Bangladesh. The results show a higher on-farm livelihood diversification in the areas with high rainfall (1500–2100 mm) compared to medium (900–1500 mm) and very high rainfall regimes (>2100 mm). Based on this study, the optimal range of rainfall for better agricultural livelihood in the context of changing environmental circumstances is from 1500 to 2100 mm. In terms of farm practices changed (proxy of adaptability), farmers responded more frequently to the market-related drivers than climatic stressors. Farmers in climate vulnerable areas (Bihar and coastal Bangladesh for instance) responded more to climatic stressors than those living in relatively less vulnerable areas (Terai for instance). The results imply that livelihood strategies should be tailor-made along the climatic resources such as rainfall, considering other biophysical and socio-economic variations at the spatial scale. Identifying household and farm-level coping strategies along the rainfall gradient can also be useful in targeting interventions to build resilience to shocks.     

Entomotoxicity and biosafety assessment of PEGylated acephate nanoparticles: A biologically safe alternative to neurotoxic pesticides

This is a report of an experimental study on a nanoencapsulation of the organophosphate acephate. Acephate was encapsulated in polyethylene glycol, using a simple, easy-to-replicate method that required no special equipment or conditions. The nanoencapsulation (nanoacephate) was characterized and its bioefficacy as compared to the regular commercial acephate was tested. The biosafety of the new compound was also tested on a murine model. Our new nanoencapsulation scored over the regular variety on all counts. It was found to successfully incorporate the active pesticidal component, acephate and this compound retained greater functional integrity over time as a nanoencapsulation. It was significantly more efficacious than the regular variety. It was biosafe when tested on murine model. We have reason to believe that this nanoencapsulation would allow the use of an organophosphate in a more targeted manner, thereby making it a cost-effective and eco-friendly alternative to the regular variety in use now.     

Evaluation of the presence-absence (P-A) test: A simplified bacteriological test for detecting coliforms in rural drinking water of India

One thousand three-hundred and ninety-four drinking water sources comprising ground water, surface water and piped supplies were tested in order to compare the presence-absence (P-A) test with standard MPN method to detect coliforms as indicators of water quality. Out of 1394 samples, 1074 (77.04%) and 1030 (74.88%) were positive by the MPN and P-A test, respectively. The P-A test detected 96% of the positives detected by the MPN test. The P-A test may be effectively used as a rapid screening method to detect coliform contamination in less polluted sources such as ground water and piped supplies.     

Potability of water sources in relation to metal and bacterial contamination in some northern and north-eastern districts of India

A total of 1094 water samples from 326 springs, 207 streams, 183 dug wells, 151 piped supplies, 90 tube wells, 75 hand pumps, 60 rivers and 2 lakes were collected from eight northern and six north-eastern districts of India. Samples were analysed to assess their potability by estimating the level of heavy metals and bacterial (coliform and faecal coliform) contaminations. Iron was found in a maximum number (53%) of water samples from hand pumps, followed by lead in 43% of the tube wells, chromium in 16% of dug wells, cadmium in 13% of streams and manganese in 7% of hand pumps above their maximum admissible concentrations (MACs). Maximum metal pollution has been observed in a considerable number of water samples from Doda, followed by Almora, Mirzapur and Bankura. Hand pump water samples exhibited maximum metal pollution followed by dug well, spring, stream and river water samples. Contamination of coliform and/or faecal coliform bacteria ranged between 41% and 67% of water samples from open water sources but it was also less, i.e. 6–15% of water samples from tube wells and hand pumps. In general, 42–85% of water samples from districts surveyed, except from Jammu (18%) and Mirzapur (27%), were found to be bacteriologically unsatisfactory. Since toxic metals and pathogenic bacteria pose a risk to public health, monitoring of drinking water sources is required.     

Quality of water obtained by tapping shallow seepages in the Almota Hills,India

We studied the quality of water obtained using a new method of tapping underground water seepages by digging shallow water collection chambers in the Almora Hills of the state of Uttar Pradesh, India; quality of this water was compared with that of water obtained using traditional water sources in this region, namely naulas (surface seepages) and springs.Water from both the new and the traditional water sources had an excess of chromium and, in some samples, of iron and lead. Microbiological analysis showed that water from new water sources was safer than that obtained from tradional sources; however, only 40% of the shallow seepages provided water conforming to WHO standards on water quality.We conclude that tapping of underground water seepages may be a useful method of providing potable water to populations living in the hills. However, further improvement is necessary in the maintenance of the clean catchment area and in disposal of waste water from these water sources to ensure water quality.     

Heavy Metal Uptake By Scirpus Littoralis Schrad. From Fly Ash Dosed and Metal Spiked Soils

Scirpus littoralis is a wetland plant commonly found in Yamuna flood plains of Delhi, India. The ability of Scirpus littoralis to take up and translocate five metals- Mn, Ni, Cu, Zn and Pb from fly ash dosed and metal spiked soils were studied under waterlogged and field conditions for 90 days. Scirpus littoralis accumulated Mn, Ni, Cu, Zn and Pb upto a maximum of 494.92, 56.37, 144.98, 207.95 and 93.08 ppm dry wt., respectively in below ground organs (BO) in 90 days time. The metal content ratios BO/soil (B/S) were higher than shoot/soil ratios (T/S) for all the metals, the highest being for Ni. Metal ratios BO/water (B/W) were also higher than shoot/water (T/W) ratios but the B/W ratio was maximum for Zn. The changes in nutrient status (N, P) in soil water and plants were also studied at interval of 30 days. The Pearson's correlation between metal uptake and N, P uptake were calculated. All the metals except Ni showed negative correlation with nitrogen but they were all non-significant. However, P uptake showed positive correlations with all the metals and all were significant at 1% confidence limit.     

A Receptor Climatology of Trajectories Originating in New York State

Air parcel trajectories originating from three locations in New York State are calculated for a three year period using the ARL-ATAD long-range transport model. Model output consisting of a trajectory segment's end point longitude and latitude position are analyzed to describe the long-range transport climatology by computing the frequency of occurrence of segment end points terminating over 33 receptor areas comprising east-central North America and a portion of the Atlantic Ocean. Results of the frequency of occurrence data show how often air pollutants emitted at or near the origin may be expected to drift over a specific downwind region. For the New York City airshed, it was found that 26.2% of the trajectories remain over New York State for transport times of 3 h and the frequency decreases to 5.2% after 24 h of transport. Approximately 40% of all trajectories are found to be over the Atlantic Ocean after 3 h of transport. When allowances are made for losses of data over the Atlantic Ocean, up to 64% of all trajectories are over the Atlantic Ocean after 24 h of transport. This frequency of trajectories over the Atlantic Ocean was found to be in agreement with wet and dry deposition modeling results conducted for power plants in New York City.