The application of nanotechnology in pesticide delivery is relatively new and in the early stages of development. This technology aims to reduce the indiscriminate use of conventional pesticides and ...ensure their safe application. This critical review investigated the potential of nanotechnology, especially the nanoencapsulation process for pesticide delivery. In-depth investigation of various nanoencapsulation materials and techniques, efficacy of application, and current research trends are also presented. The focus of ongoing research was on the development of a nanoencapsulated pesticide formulation that has slow releasing properties with enhanced solubility, permeability, and stability. These properties are mainly achieved through either protecting the encapsulated active ingredients from premature degradation or increasing their pest control efficacy for a longer period. Nanoencapsulated pesticide formulation is able to reduce the dosage of pesticides and human exposure to them, which is environmentally friendly for crop protection. However, lack of knowledge of the mechanism of synthesis and lack of a cost-benefit analysis of nanoencapsulation materials hindered their application in pesticide delivery. Further investigation of these materials' behavior and their ultimate fate in the environment will help the establishment of a regulatory framework for their commercialization. The review provides fundamental and critical information for researchers and engineers in the field of nanotechnology and especially the use of nanoencapsulation techniques to deliver pesticides.
Hydrocarbons are relatively recalcitrant compounds and are classified as high-priority pollutants. However, these compounds are slowly degraded by a large variety of microorganisms. Bacteria are able ...to degrade aliphatic saturated and unsaturated hydrocarbons via both aerobic and anaerobic pathways. Branched hydrocarbons and cyclic hydrocarbons are also degraded by bacteria. The aerobic bacteria use different types of oxygenases, including monooxygenase, cytochrome-dependent oxygenase and dioxygenase, to insert one or two atoms of oxygen into their targets. Anaerobic bacteria, on the other hand, employ a variety of simple organic and inorganic molecules, including sulphate, nitrate, carbonate and metals, for hydrocarbon oxidation.
► Comprehensive and critical literature review on various adsorbents used for defluoridation. ► pH, temperature, kinetics and co-existing anions effects on F adsorption. ► Choice of adsorbents for ...various circumstances. ► Adsorption thermodynamics and mechanisms. ► Future research on efficient, low cost adsorbents which are easily regenerated.
Excessive intake of fluoride (F), mainly through drinking water, is a serious health hazard affecting humans worldwide. There are several methods used for the defluoridation of drinking water, of which adsorption processes are generally considered attractive because of their effectiveness, convenience, ease of operation, simplicity of design, and for economic and environmental reasons. In this paper, we present a comprehensive and a critical literature review on various adsorbents used for defluoridation, their relative effectiveness, mechanisms and thermodynamics of adsorption, and suggestions are made on choice of adsorbents for various circumstances. Effects of pH, temperature, kinetics and co-existing anions on F adsorption are also reviewed. Because the adsorption is very weak in extremely low or high pHs, depending on the adsorbent, acids or alkalis are used to desorb F and regenerate the adsorbents. However, adsorption capacity generally decreases with repeated use of the regenerated adsorbent. Future research needs to explore highly efficient, low cost adsorbents that can be easily regenerated for reuse over several cycles of operations without significant loss of adsorptive capacity and which have good hydraulic conductivity to prevent filter clogging during the fixed-bed treatment process.
Uranium contamination of soil has been a major concern with respect to its toxicity, accumulation in the food chain and persistence in the environment. Owing to these problems, remediation of ...uranium-contaminated soils has been investigated by various techniques. This review focuses on the challenges and complexities associated with the remediation of uranium-contaminated soil at field level. Therefore, laboratory studies have been excluded from this review. Challenges faced during remediation of uranium-contaminated soil using various techniques such as microbial/phyto/chemical/material based strategies have been discussed with suitable examples. Various factors that have a major influence on uranium decontamination process in soil such as soil type, uranium speciation, the presence of coexisting ions and organics, etc., have been highlighted. This review brings out the significance of the integrated role of various factors which determine the efficiency of the uranium decontamination process.
•Uranium contamination of soil has been a major concern.•Remediation of uranium-contaminated soils investigated by various techniques.•Challenges faced and complexities in remediation discussed.•Significance of the integrated role of various factors in uranium decontamination process.
Although microplastics (MPs) are ubiquitous contaminants in different ecosystems, their interactions with other pollutants including heavy metals remain relatively unknown. Wheat is an important ...grain that makes the basis of human food in many parts of the world. Thus, pollutants that affect its production are important subjects of study. This research focuses on the possible effects of the transport of the adsorbed heavy metals onto MPs to the roots of growing wheat. The adsorption of three heavy metals (Pb, Cd, and Zn) onto PET particles was examined. Pb and Cd were selected because they are known to be toxic, while Zn is an essential nutrient for plants. Adsorption experiments were performed using 1 g of PET-MP particles in 20 ml of five different concentrations of each individual element (Pb, Cd, and Zn) (denoted as S-elements). To investigate the antagonistic and synergistic effects of these elements on each other, they were studied collectively with all 3 elements present (denoted as C-elements). Desorption experiments were then performed for three scenarios in which the wheat rhizosphere zone was simulated. Generally, the concentration of the investigated heavy metals adsorption on polyethylene terephthalate (PET) decreased in the order: S-Cd > S-Zn > S-Pb and C-Zn > T-Cd > C-Pb. PET particles exposed to Zn, Cd, and Pb solution adsorbed from 7.2 to 8.5%, 5.3 to 9.8%, and 29.8 to 68.5% of the initial heavy metals concentration, respectively. 11.3 to 15.2%, 12.5 to 23.35%, and 5.5 to 33.6% of the initially adsorbed Zn, Cd, and Pb were desorbed in the wheat rhizosphere zone in the three defined scenarios, respectively. The results show that PET particles can act as a vector in transferring heavy metals to the rhizosphere zone.
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•Heavy metals (Pb, Cd, and Zn) accumulated on PET-MPs particles•Adsorbed Zn, Cd, and Pb desorbed in the wheat rhizosphere zone in three scenarios•PET particles can transport heavy metals within the rhizosphere zone.
Globally, millions of people who rely on groundwater for potable purposes and agriculture have been inadvertently exposed to toxic arsenic (As) because of its natural occurrence in groundwater in ...several countries of Asia, Europe and America. While the presence of As in groundwater and its impacts on human health have been documented in many countries, there is little information on As contamination in Pakistan. This review highlights, for the first time, the extent and severity of As-induced problems in Pakistan based on relevant published papers; discusses possible sources of As contamination of aquifers; and estimates As-induced potential health hazards in the country in relation to global data. Data from 43 studies (>9882 groundwater samples) were used to describe As variability in groundwater of Pakistan and for comparison with global data. The mean groundwater As content reported in these studies was 120 μg/L (range: 0.1–2090 μg/L; SD: ±307). About 73% of the values for mean As contents in the 43 studies were higher than the World Health Organization (WHO) permissible limit (10 μg/L) for drinking water, while 41% were higher than the permissible limit of As in Pakistan (50 μg/L). It was observed that groundwater samples in some areas of Punjab and Sindh provinces contained high As concentrations which were almost equal to concentrations reported in the most contaminated areas of the world. We predicted that the mean values of ADD, HQ and CR were 4.4 μg kg−1day−1 (range: 0–77 μg kg−1day−1), 14.7 (range: 0–256) and 0.0029 (range: 0–0.0512), respectively, based on mean As concentrations reported in Pakistan. In addition, this article proposes some integrated sustainable solutions and future perspectives keeping in view the regional and global context, as well as the on-ground reality of the population drinking As-contaminated water, planning issues, awareness among civil society and role of the government bodies. Based on available data, it is predicted that almost 47 million people in Pakistan are residing in areas where more than 50% of groundwater wells contain As concentrations above the WHO recommended limit of As in drinking water.
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•In Pakistan, arsenic (As) concentrations exceed above WHO safe limit (10 μg/L) in some areas.•This is the first review critically analyzing published data on groundwater As in Pakistan.•Total 43 studies (>9882 groundwater samples) were used to describe As spatial variability.•Sustainable solutions and important perspectives are proposed in regional and global context.•Over 47 million people are estimated to be at potential risk of As poisoning in Pakistan.
Capsule: This review describes arsenic contamination of groundwater and associated health risks in Pakistan considering proposed scientific solutions proposed at global and regional scales.
Cadmium Sorption and Desorption in Soils: A Review LOGANATHAN, PARIPURNANDA; VIGNESWARAN, SARAVANAMUTHU; KANDASAMY, JAYA ...
Critical reviews in environmental science and technology,
03/2012, Letnik:
42, Številka:
5
Journal Article
Recenzirano
Cadmium (Cd) is an environmental pollutant that can be readily taken up by plants and may enter the food chain, causing risk to human health. It can also affect soil quality and, if easily leached, ...has the potential to pollute surface and ground waters. Sorption and desorption are critical processes controlling the phytoavailability and mobility of Cd in soils. The authors present the present knowledge on the mechanisms and hysteresis of Cd sorption and desorption in soils and factors such as pH, ionic strength, index cation, other heavy metal cations, inorganic anions, organic ligands, Cd loading rate, and the type and amounts of organic matter and inorganic colloids influencing these processes. The methods used to determine the nature and magnitude of Cd sorption and desorption are also critically reviewed.
Though several in-situ treatment methods exist to remediate polluted sites, selecting an appropriate site-specific remediation technology is challenging and is critical for successful clean up of ...polluted sites. Hence, a comprehensive overview of all the available remediation technologies to date is necessary to choose the right technology for an anticipated pollutant. This review has critically evaluated the (i) technological profile of existing in-situ remediation approaches for priority and emerging pollutants, (ii) recent innovative technologies for on-site pollutant remediation, and (iii) current challenges as well as future prospects for developing innovative approaches to enhance the efficacy of remediation at contaminated sites.
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•The global picture of chemical pollution in the environment is often fragmented.•This perspective highlights global picture of pollution regarding catastrophic risk.•Exposure related ...impact on fertility, cognition and food safety are discussed.•Prioritised strategies for curbing chemical dispersal are recommended.
Anthropogenic chemical pollution has the potential to pose one of the largest environmental threats to humanity, but global understanding of the issue remains fragmented. This article presents a comprehensive perspective of the threat of chemical pollution to humanity, emphasising male fertility, cognitive health and food security. There are serious gaps in our understanding of the scale of the threat and the risks posed by the dispersal, mixture and recombination of chemicals in the wider environment. Although some pollution control measures exist they are often not being adopted at the rate needed to avoid chronic and acute effects on human health now and in coming decades. There is an urgent need for enhanced global awareness and scientific scrutiny of the overall scale of risk posed by chemical usage, dispersal and disposal.
Heterogeneous photocatalysis involving titanium dioxide (TiO
2) appears to be the most promising technology for organic dyes degradation. This paper presents a critical review of novel achievements ...in the modification of TiO
2 aimed at: enhanced TiO
2 photocatalytic efficiency, complete mineralization of organic dyes, efficient utilization of visible/solar light, stability and reproducibility of modified titania, recycle and reuse in real wastewater treatment.
Organic dyes are one of the largest groups of pollutants released into wastewaters from textile and other industrial processes. Because of potential toxicity of the dyes and their visibility in surface waters, removal and degradation of organic dyes have been a matter of considerable interest. A wide range of methods have been developed, amongst which the heterogeneous photocatalysis involving titanium dioxide (TiO
2) appears to be the most promising technology. This paper presents a critical review of novel achievements in the modification of TiO
2 photocatalytic systems aimed at: enhanced TiO
2 photocatalytic efficiency; complete mineralization of organic dyes; efficient utilization of visible and/or solar light; stability and reproducibility of the modified TiO
2; recycle and reuse in real wastewater treatment.
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