Phytoremediation of PAHs in Contaminated Soils: A Review

Polycyclic aromatic hydrocarbons (PAHs), which are also part of persistent organic pollutants (POPs), are considered to be especially toxic to humans (carcinogenic), likewise to plants, microorganisms and other living organisms. PAHs soil contamination occurs by storage leaking, transport loss, the land disposal of petroleum waste, and accidental or intentional spills. Due to their ubiquitous occurrence, recalcitrance, bioaccumulation potential and carcinogenic activity, PAHs are a significant environmental concern. The methods of controlling and repairing PAH-contaminated soils mainly include physical remediation, chemical remediation and phytoremediation. However, there was an increasing focus on phytoremediation technologies as a result of their unique advantages, including low cost, lack of secondary pollution and large-area application. Phytoremediation is therefore one of the soil remediation technologies with the greatest potential.

Remediation Techniques for Cadmium-Contaminated Dredged River Sediments after Land Disposal

This paper examines the remediation techniques of cadmium (Cd)-contaminated dredged river sediments after land disposal in a city in East China. Three remediation techniques, including stabilization, soil leaching, and phytoremediation, are compared by analyzing the performance of the techniques for Cd-contaminated soil remediation. The experimental results showed that the stabilization technique reduced the leaching rate of soil Cd from 33.3% to 14.3%, thus effectively reducing the biological toxicity of environmental Cd, but the total amount of Cd in soil did not decrease. Leaching soil with citric acid and oxalic acid achieved Cd removal rates of 90.1% and 92.4%, respectively. Compared with these two remediation techniques, phytoremediation was more efficient and easier to implement and had less secondary pollution, but it took more time, usually several years. In this study, these three remediation techniques were analyzed and discussed from technical, economic, and environmental safety perspectives by comprehensively considering the current status and future plans of the study site. Soil leaching was found to be the best technique for timely treatment of Cd contamination in dredged river sediments after land disposal.

Fictions of Surplus

This chapter, focusing comparatively on the Canadian and UK experiences, explores one particular component of the wide-ranging work involved in privatizing and commodifying public land: the discursive component. It turns to a context where land commodification is driven less by extra-economic force and more by the lure of economic efficiency. The chapter examines the land “fictions” or legitimizing narratives — not just about land per se but about the different types of owners it can have — to rationalize and justify the process of commodification. It reveals that the kernel of these fictions is the particular idea invoked by the state that public land is often “surplus” land, and thus free to be commodified. The chapter details how surplus labels are readied, and land released to the private sector, through techniques of (dis)incentivization, the normalization of public land disposal practices, and the transfer of authority to different actors. Ultimately, the chapter presents three main sections: some essential preparatory material, the pivotal concept of “surplus,” considering its distinctive articulation and coloring in each national context, and the ways in which these fictions of surplus are brought to life.

Fictions of Safety

This chapter explores the flipside of public land disposal, turning to the financial dynamics that have led institutional investors to aggressively incorporate rural farmland, long-term commercial leases, surplus public land inventories, and other low-rent-yielding properties into their portfolios, thereby transforming land into a fungible global asset. It investigates how shocks in asset prices in the wake of the 2008 global financial crisis led investors to mobilize defensive understandings of land. In contrast to the more commonly studied speculative storylines of closing rent and yield gaps, the chapter exposes how the narration of land as a “safe” asset is significant in shaping patterns of global land investment, banking the stability of financial markets on social presumptions of land's countercyclicality and capacity to retain value. While these performative storylines build on historical patterns and statistical pictures, the fiction of safety that they collectively enact also fuels fresh risk taking, putting land to use in ways more tightly attuned to the logics and cycles of international finance and thereby undermining the fixity of the ground itself. Ultimately, the chapter aims to shed light on the financial sector not only as a key driver of global land and property transformations but one whose defensive strategies continue to shape US security in divergent ways.

From dumpsites to engineered landfills: A systematic review of risks to occupational and public health

Disposal on land has persisted as the most predominant form of waste disposal for millennia and despite advances in modern engineered landfills, large quantities (405 Mt y-1) of collected municipal solid waste (MSW) are still deposited and concentrated in open, uncontrolled dumpsites throughout low- and middle-income countries (LIMICs) worldwide – a key form of waste mismanagement. These pose major threats to the health and safety of surrounding populations and mainly waste pickers who across the Global South target dumpsites to salvage and recycle under minimal protection measures. Here, we conducted an adapted PRISMA systematic review, distilling over 3,000 papers into 40 core sources from 22 countries, to critically assess the evidence on the associated risks. We identified prevalent hazard-pathway-receptor combinations and subsequently scored, compared and ranked the relative risk of exposure to harm experienced by various actors in land disposal sites. Our assessment indicates high risk levels experienced through interaction with medical waste, emissions from waste combustion, and critically through the fatal risk of waste slope failure, claiming the lives of at least (on average) of 34 people per year since 1992. Despite the strong anecdotal signals on the generic nature of the health and safety challenges at hand, many of the sources lack critical information with which to determine and link causality of health effects with the existence, or even exposure to emissions or other hazards. Yet, our critical analysis clearly demonstrates an unacceptable potential for damage to human health and safety; alerting us on the need to close, and immediately manage risks at dumpsites, preventing harm to some of the worlds’ poorest inhabitants. Our aspiration is that quantification and mitigation of risks from dumpsites attracts substantial and scientifically robust efforts.

Identification and restoration of unused agricultural land based on planned land inventory

The article considers the procedure for identification of unused agricultural land for its involvement in economic turnover. The object of study is the Yaroslavl and Smolensk regions of the Russian Federation, where the share of unused agricultural land is from 12 to 50%. This identification is based on the methods of planned land inventory, the main purpose of which is to assess the reasons for land disposal, the cultural and technical conditions of land and preparation of recommendations for introduction of lands into agricultural circulation. This work includes the proposals to establish the order of involvement of land plots into economic turnover.

Assessment of Characterization of Leachate Generated using Leachate Generated Model

There are many approaches which have been used to assess the ground water and surface water contamination. The land disposal of municipal waste is potential cause of groundwater contamination unscientifically managed dumping yards are prone to groundwater contamination because of leachate production. The leaching behaviour of a waste can be assessed either by the experimental determination of the characteristics of leachate generated or through mathematical modeling.A pilot study was conducted to assess the characterization of leachate generating using Leachate Generated Model (LGM). In present study the model is used to study the effect of gomutra and enzymes on the municipal solid waste and the leachate quality. The result indicated that the colour of leachate generated in study area was found to be oxygenated and has organic compound which resulted in increased permeability. The results reveal that the use of gomutra (15%) mixed with MSW, was a good indication that organic matters in leachate are readily biodegradable in mature land fill, where as 10% gomutra used in MSW, showed that (BOD / COD = 0.64) leachate had high biodegradability through anaerobic phase. This stimulator showed better result than enzymes used and is also helpful to prevent containing of waste water tube wells and bore holes affected from leachate generated.

Examination on GGBS based Geopolymer Mortar at Elevated Temperatures

In India approximately 120 million tonnes of flyash is produced every year from thermal power stations and enormous quantities of stone dust, a waste product, produced from the aggregate crusher units at the time of rubble crushing. Usage or disposal of this by-product within the framework of its economic structure becomes a challenging problem to every country because of increasing interest in conservation of energy and resources and growing concern with environmental issues. Also Land disposal becomes a serious problem due to scarcity of land. Due to this the M-sand and GGBS is used as ingredients in mortar which enhance the properties of mortar and utilization of M-sand is helpful for consumption. To study the alkaline solution of NaOH and Na2SiO3 is mixed with processed fly ash to become geopolymer mortar. This mortar cubes at different molarities and different temperature so as to increase the strength of the cubes.