John Pichtel

Role of proline under changing environments: A review

When exposed to stressful conditions, plants accumulate an array of metabolites, particularly amino acids. Amino acids have traditionally been considered as precursors to and constituents of proteins, and play an important role in plant metabolism and development. A large body of data suggests a positive correlation between proline accumulation and plant stress. Proline, an amino acid, plays a highly beneficial role in plants exposed to various stress conditions. Besides acting as an excellent osmolyte, proline plays three major roles during stress, i.e., as a metal chelator, an antioxidative defense molecule and a signaling molecule. Review of the literature indicates that a stressful environment results in an overproduction of proline in plants which in turn imparts stress tolerance by maintaining cell turgor or osmotic balance; stabilizing membranes thereby preventing electrolyte leakage; and bringing concentrations of reactive oxygen species (ROS) within normal ranges, thus preventing oxidative burst in plants. Reports indicate enhanced stress tolerance when proline is supplied exogenously at low concentrations. However, some reports indicate toxic effects of proline when supplied exogenously at higher concentrations. In this article, we review and discuss the effects of exogenous proline on plants exposed to various abiotic stresses. Numerous examples of successful application of exogenous proline to improve stress tolerance are presented. The roles played by exogenous proline under varying environments have been critically examined and reviewed.

Phytoremediation of subarctic soil contaminated with diesel fuel

The effects of several plant species, native to northern latitudes, and different soil amendments, on diesel fuel removal from soil were studied. Plant treatments included Scots Pine (Pinus sylvestris), Poplar (Populus deltoides x Wettsteinii), a grass mixture (Red fescue, Fesuca rubra; Smooth meadowgrass, Poa pratensis and Perennial ryegrass, Lolium perenne) and a legume mixture (White clover, Trifolium repens and Pea, Pisum sativum). Soil amendments included NPK fertiliser, a compost extract and a microbial enrichment culture. Diesel fuel disappeared more rapidly in the legume treatment than in other plant treatments. The presence of poplar and pine enhanced removal of diesel fuel, but removal under grass was similar to that with no vegetation. Soil amendments did not enhance diesel fuel removal significantly. Grass roots accumulated diesel-range compounds. This study showed that utilisation of selected plants accelerates removal of diesel fuel in soil and may serve as a viable, low-cost remedial technology for diesel-contaminated soils in subarctic regions.

Waste management practices : municipal, hazardous, and industrial

Preface HISTORICAL AND REGULATORY DEVELOPMENT Introduction A Brief History of Waste Management Regulatory Development SOLID WASTES AND THEIR MANAGEMENT Characterization of Solid Waste Municipal Solid Waste Collection Recycling Solid Wastes MSW Processing Materials Recovery Facilities Composting MSW Incineration of MSW The Sanitary Landfill HAZARDOUS WASTES Identification of Hazardous Waste Hazardous Waste Generator Requirements Hazardous Waste Transportation Treatment, Storage and Disposal Facility Requirements Incineration of Hazardous Wastes Hazardous Waste Treatment Land Disposal of Hazardous Waste SPECIAL CATEGORIES OF WASTE Universal Wastes Management of Used Oil Medical and Infectious Wastes Construction and Demolition Debris Electronics Waste Appendix

Trace metal bioavailability in municipal solid waste and sewage sludge composts

A sequential extraction procedure was employed to determine the soil fractions, and assess plant availability of Cr, Cu, Ni, Pb and Zn in a Glynwood silt loam amended with five rates (0, 30, 60, 120 and 240 metric tons/ha) of composted municipal solid waste (CMSW) or composted sewage sludge (CSS) cropped to oats (Avena sativa). The application of the composts tended to shift the solid phase forms of the metals away from those extractable with HNO3 to those extractable with NaOH and EDTA. The more labile fractions (KNO3 and H2O extracts) of the metals typically decreased with application of CMSW and CSS. Crop dry matter increased at the 30 and 60 MT/ha CMSW rates by 142 and 152%, respectively, after which yields declined to below control values. Yields at all rates of CSS declined. The CMSW and CSS had an insignificant effect on concentrations of Cr and Pb in oat tissue, but tissue levels of Cu, Ni and Zn increased with increased rate of compost application.

Distribution and Fate of Military Explosives and Propellants in Soil: A Review

Energetic materials comprise both explosives and propellants. When released to the biosphere, energetics are xenobiotic contaminants which pose toxic hazards to ecosystems, humans, and other biota. Soils worldwide are contaminated by energetic materials from manufacturing operations; military conflict; military training activities at firing and impact ranges; and open burning/open detonation (OB/OD) of obsolete munitions. Energetic materials undergo varying degrees of chemical and biochemical transformation depending on the compounds involved and environmental factors. This paper addresses the occurrence of energetic materials in soils including a discussion of their fates after contact with soil. Emphasis is placed on the explosives 2,4,6-trinitrotoluene (TNT), hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), and octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and the propellant ingredients nitroglycerin (NG), nitroguanidine (NQ), nitrocellulose (NC), 2,4-dinitrotoluene (2,4-DNT), and perchlorate.

Phytoremediation of Soil Contaminated with Used Motor Oil: II. Greenhouse Studies

The decomposition of used motor oil in soil as influenced by plant treatment was monitored in a greenhouse study. Soil contaminated with used motor oil (1.5% w/w) was seeded with soybean (Glycine max)/green bean (Phaseolus vulgaris); sunflower (Helianthus annus)/Indian mustard (Brassica juncea); mixed grasses/maize (Zea mays); and mixed clover (red clover, Trifolium pratense/ladino clover, Trifolium repens) and incubated. Soxhlet-extractable oil and grease remaining in the soil was monitored after 100 and 150 days. After 150 days in the clover treatment, the added oil was no longer detected. A total of 67% of the oil was removed in sunflower/mustard, and with addition of NPK fertilizer, the oil was completely removed. The grass/maize treatment resulted in a 38% oil reduction, which increased to 67% with fertilizer application. The control treatment reduced oil in soil by 82% when fertilizer was added. At 150 days the sunflower/mustard and wheat/oats treatments produced the greatest biomass in the presence...

Degradation of diesel fuel in rhizosphere soil

Little is known regarding the ability of the plant rhizosphere to decompose diesel range organic (DRO) compounds in soil. A growth chamber study was conducted to assess the decomposition of DROs in soil as affected by grasses and legumes. A sandy loam soil was contaminated with 2% (w/w) commercial diesel fuel, and was treated with: (a) mixed NPK fertilizer; (b) urea; (c) glucose; and (d) control (i.e., no additives). Soil was seeded with either a grass mix (Poa, Phleum, Agrostis ), a legume mix (Pisum sativum, Trifolium pratense); or no vegetation; and incubated. Over 150 days, approximately 10.6% of DROs was lost by volatilization. There was a trend toward decomposition of certain long-chain aliphatics in several treatments. DROs decreased most rapidly with the NPK fertilizer, regardless of plant cover. DRO concentrations were consistently lower under legumes compared to the other crop treatments, regardless of fertilizer treatment. The glucose treatment had lowest DRO reductions, presumably due to prefe...

Phytoextraction of Pb and Cd from a superfund soil : Effects of amendments and croppings

In a growth chamber, maize (Zea mays) and Indian mustard (Brassica juncea) were grown over two croppings in soil from a Superfund site (PbTotal = 65,200 mg/kg and CdTotal = 52 mg/kg). Soil treatments consisted of ethylenediaminetetraacetic acid, sodium citrate and composted sewage sludge, each at two rates (EDTA .05%, EDTA .2%, citrate .05%, citrate .2%, CSS 5% and CSS 10%, respectively). In most cases, the EDTA and citrate treatments were superior in terms of solubilizing soil Pb for root uptake and translocation into above-ground biomass. In the first maize crop, the EDTA .2% treatment resulted in 2435 and 9389 mg/kg Pb in shoot and root tissues, respectively. The CSS treatments typically resulted in lowest Pb and Cd removal efficiencies. Lead remaining in the soil after two croppings was mainly associated with the carbonate, organic, and residual fractions, which represent the less bioavailable forms. Soil Cd was generally more mobile for plant uptake than soil Pb. The EDTA .2% and citrate treatments were most successful in promoting Cd uptake by both maize and mustard. Although Pb concentrations (mg/kg tissue) were lower for maize than mustard, the former removed more total Pb (0.2 mg per pot, mean over all treatments), compared to mustard (0.03 mg), by virtue of its higher biomass production.

Lead Extraction from Soils as Affected by Lead Chemical and Mineral Forms

Soil washing is one of several technologies for the removal of lead (Pb) from soil. Recent studies have focused on washing efficiency using artificially contaminated soils; however, data may not reflect the efficiency of Pb removal for aged, field-contaminated soils. A Glynwood silty clay loam, a river sediment and a sand were artificially contaminated with PbSO4. These, and soil material from a battery recycling/smelting Superfund site, were washed in batch tests with ethylenediaminetetraacetic acid (EDTA), pyridine-2,6-dicarboxylic acid (PDA) (0.0225 M, 0.0375 M, and 0.075 M) or hydrochloric acid (HCl) (0.1 and 1.0 N). Using a sequential extraction procedure, 96% or more of the Pb in the artificially contaminated soils and 65% of the Pb in the Superfund soil were determined to be extractable. X-ray diffraction techniques revealed the presence of both anglesite (PbSO4) and hydrocerrusite (Pb3[CO3]2[OH]2Pb) in the Glynwood and sand, and in the river sediment, massicot (PbO) was also detected. Metallic Pb ...

Mycorrhizae: An Overview

Mycorrhizae establish symbiotic relationships with plants and play an essential role in plant growth, disease protection, and overall soil quality. Of the seven types of mycorrhizae described in current scientific literature (arbuscular, ecto, ectendo, arbutoid, monotropoid, ericoid and orchidaceous mycorrhizae), the arbuscular and ectomycorrhizae are the most abundant and widespread. This chapter presents an overview of current knowledge of mycorrhizal interactions, processes, and potential benefits to society. The molecular basis of nutrient exchange between arbuscular mycorrhizal (AM) fungi and host plants is presented; the role of AM fungi in disease protection, alleviation of heavy metal stress and increasing grain production is also reviewed. Use of mycorrhizae, primarily AM and ectomycorrhizae (ECM), on plant growth promotion and disease suppression are discussed and their implications on sustainable agriculture are considered. The effect of co-inoculation of AM fungi and beneficial saprophytic mycoflora, in terms of plant growth promotion and root colonization, are discussed. The role of AM fungi in the restoration of native ecosystems and the mycorrhizosphere effect of multitrophic interactions are briefly outlined. The mechanisms by which mycorrhizae transform a disturbed ecosystem into productive land are briefly discussed. The importance of reintroduction of mycorrhizal systems in the rhizosphere is emphasiszed and their impact in landscape regeneration and in bioremediation of contaminated soils are discussed. The importance of ECM in forest ecosystems, and associations of ECM in tropical rainforests and their function in maintaining tropical monodominance are discussed. In Vitro mycorrhization of micropropagated plants and visualizing and quantifying endorhizal fungi are briefly explained.