ISSN:
Annals of Environmental Science and Toxicology
Review Article       Open pjestcess      Peer-Reviewed

Nanoparticles in Biosolids: Effect on Soil Health and Crop Growth

Abioye O Fayiga* and Uttam K Saha1

The University of Georgia, 2300 College Station Road, Athens, GA 30602, USA
*Corresponding author: Abioye O Fayiga, The University of Georgia, 2300 College Station Road, Athens, GA 30602, USA; E-mail: abioyeg@aol.com
Received: 27 March, 2018 | Accepted: 15 April, 2018 | Published: 17 April, 2018
Keywords: Nanoparticles; Biosolids; Soil health; Plant growth; Land application

Cite this as

Fayiga AO, Saha UK (2017) Nanoparticles in Biosolids: Effect on Soil Health and Crop Growth. Ann Environ Sci Toxicol 2(1): 059-067. DOI: 10.17352/pjest.000013

Nanoparticles are becoming popular from their use in medicine for therapy, diagnostics and imaging, in pharmacy for drug delivery, to its use in electronics, engineering and manufacturing industries. This wide application has increased their presence in the environment especially in wastewater from municipal and industrial sources. They end up in the final product; biosolids which are treated sewage sludge from wastewater treatment plants. Due to limited space in landfills and cost effectiveness, biosolids are predominantly disposed in land applications as organic fertilizer for crop production or land reclamation. Nanoparticles have been detected in wastewater and biosolids raising concerns about their effect on soil health and crop growth.

While a large number of studies have been conducted on effect of nanoparticles on seed germination and plant growth, few studies have been carried out using biosolids. The sole effect of nanoparticles may be different from when it’s present in biosolids due to reaction with some components in biosolids. Hence more work is needed in this area to provide direction for regulation of biosolids. Studies have reported both positive and negative effects of nanoparticles on plant growth showing that it depends on plant species, type of nanoparticle, and dose of nanoparticle and method of application. There is also very little work on effect of nanoparticles on soil health. Most of the work done has shown the antimicrobial effect of some nanoparticles which could affect nutrient release from the organic matter fraction in the soil and disrupt some plant-microbe relationships that promote soil fertility. Although nanoparticles have proved beneficial in many aspects of life, they need to be monitored due to their increasing use in the environment.

Introduction

Nanoparticles are used in a wide range of consumer products with applications in the fields of medicine, pharmacy, electrical appliances and manufacturing industries. It has been estimated that greater than 15% of consumer products have some kind of nanotechnology incorporated into their manufacturing process [1]. The increase in production of nanoparticles will ultimately increase their release into the environment especially via municipal and industrial wastewater [2]. Several studies have confirmed the presence of nanoparticles in municipal and industrial wastewater which ends up at wastewater treatment plants (WWTPs [3-5].

Sewage sludge from wastewater treatment plants (WWTPs) is converted to biosolids after treatment to remove pathogens and volatile solids [6]. Biosolids contain both essential nutrients for plant growth and other contaminants of emerging concern such as nanoparticles, heavy metals, pharmaceuticals and personal care products. The land application of biosolids may be a potential release of these substances into the environment. While a lot of studies have been conducted on heavy metals and pharmaceuticals in biosolids, there is limited information on nanoparticles.

Although there is a lot of information on effect of nanoparticles on plant growth especially on seed germination, not much work has been done to characterize biosolids with respect to the presence of nanoparticles and their effects on plant growth and soil health [7-9]. The effect of nanoparticles determined solely on plants may be different from their effect when present in biosolids due to reactions with other components of biosolids. Hence more work is needed to determine the effect of nanoparticles in biosolids on plant growth and soil health when applied on agricultural soils.

Even though most researchers agree that the effects of organic compounds, metals, and microorganisms in biosolids are not harmful to humans or the environment if managed carefully, information of their potential impact on soil health and plant growth is still needed at this time [10]. Hence this paper provides information on nanotechnology, types of nanoparticles, nanoparticles in biosolids and their effect on soil health and plant growth.

Nanotechnology

Background

Nanotechnology has been defined as the understanding, control or manipulation of particles at scales as small as the nanometer (nm), specifically between 1 and 100 nm to create new materials with new properties and functions [11]. One nanometer (nm) is the one thousand millionth of a meter (1 nm = 10 −9 m) and this size may be its strength in many applications. Nanotechnology explores electrical, optical, and magnetic activity as well as structural behavior at the molecular and submolecular level [12]. There are two approaches of nanotechnology; first, molecular nanotechnology which involves the building of organic and inorganic structures while the second involves the breaking down of bulk materials into nanoparticles [13].

Nanotechnology has been used in energy, pharmacy, electronics, biotechnology, medicine and engineering to improve material performance [14,15]. Nanotechnology manufactures drugs in sizes as small as the nanometer scale which enhances the performance in a variety of dosage forms [14]. Advantages of nanotechnology in pharmacy includes increased surface area, increased dissolution, enhanced solubility, and increased oral bioavailability, lower dosages required and faster therapeutic action in patients [14].

In orthopedics, nanotechnology has been used in bone tissue engineering, implantable materials, diagnosis and therapeutics, and surface adhesives [16]. In dentistry, nanomaterials are being used in caries inhibitors, antimicrobial resins, hard tissue remineralizing agents, scaffolds, bio-membranes, restorative cements, adhesion promoters and boosters, reinforced methacrylate resins, root canal disinfectants, and friction free orthodontic arch wires [17]. Nanoparticles have also been used in the diagnosis, imaging, screening, and treatment of primary and metastatic tumors of lung cancer [18]. In general medicine, nanoparticles have been used in imaging probes in the treatment of cardiovascular disorders, ocular, neurodegenerative, respiratory diseases, AIDS and enhancement of wound healing [19].

In agriculture, nanotechnology has been used for the controlled release of agrochemicals (e.g., fertilizers, pesticides, and herbicides) and target-specific delivery of biomolecules (e.g., nucleotides, proteins, and activators) [20]. Nanotechnology has been used in the production of fertilizers with better release and pesticides with better broad-spectrum pest protection efficiency [21]. Nanotechnology has been used to deliver DNA to plant cells, enhance nutrient absorption, detect plant pathogens, regulate plant hormones, and in animal husbandry, nanocapsules have been devised to deliver vaccines [22]. Nanotechnology has several applications in all stages of production, processing, storing, packaging and transport of agricultural products [23]. However, most of the work on nanotechnology in agriculture are at the developmental stage and not yet commercialized [22].

Types of nanoparticles

Nanoparticles are particles ranging in size from 1 to 100 nm [24]. They are different from the bulk material and can be synthesized chemically or biologically [24]. Metallic nanoparticles such as Ag or Au have been synthesized by plants such as Azadirachta indica, Capsicum annuum and Carica papaya or microorganisms such as Verticillium sp., and Aspergillus fumigates [24, 25]. Properties of nanoparticles that contribute to their usefulness include increased surface area, surface reactivity and solubility, ability to agglomerate or change size in different media and enhanced endurance over conventional-scale substance [19].

Nanoparticles are characterized by the material, shape and magnetic property. Based on material, they can be classified Table 1 into metallic nanoparticles, carbon based nanoparticles, silica based nanoparticles, polymeric (organic) nanoparticles. Based on shape, they can be classified into quantum dots, nanotubes, nanofibres, nanorods, nanosheets, aerogel and nanoballs [19]. They can also be classified as either magnetic or non-magnetic nanoparticles.

Metallic nanoparticles can be silver (Ag), gold (Au), titanium oxide (TiO2), iron oxide (Fe2O3), zinc oxide (ZnO), or copper (Cu). Silver nanoparticles are the most commonly used as antimicrobial agents for water treatment and in textile industries; in electronics, drug delivery, and agriculture [26-29]. Gold nanoparticles are used in diagnosis of cancer, detection of cancer stem cells, in DNA fingerprinting, to detect antibiotics such streptomycin, gentamycin and neomycin, and for identification of different classes of bacteria [30]. Nanoparticles of metalloids such as Se are also commonly used in diagnostics and therapy, electronic devices, catalysis, fuel cells and bio and environmental remediations [31].

Examples of carbon nanoparticles include fullerene and graphene. Carbon nanotubes are cylindrical layers of graphene which could be single or multi walled with open and closed ends [32,33]. Individual carbon nanotube walls can be metallic or semiconducting depending on the orientation of the graphene lattice [33].

Fullerene has been used as targeted therapeutic agent in osteoporosis and cancer; proposed as drug carrier and used in diagnostic and medical imaging [34-36]. On one hand, synthesized carbon nanoparticles have been proved to be effective in removal of metal ions (Zn, Ni, Cu, Sb, Co, Cd, Cr, etc.) from contaminated water samples [37]. On the other hand, engineered carbon nanoparticles have been considered emerging environmental contaminants [38].

Silica nanoparticles are used as additive to drugs, cosmetics, food, biomedical applications and biosensors [19]. Polymeric nanoparticles are used as drug carriers for cancer therapy due to their biodegradability, biocompatibility and non-toxicity [39]. Polymeric nanoparticles are used for drug delivery techniques such as conjugation and entrapment of drugs, prodrugs, stimuli-responsive systems, imaging modalities, and theranostics [40].

Quantum dots (QDs) are a class of engineered nanoparticles with nanometer diameter size (2–10 nm) [41]. They are heterostructures with quantum confinement to zero dimensions containing nanocrystals with quantized energy levels directly related to size [42]. Nanocrystal quantum dots are semi-conducting materials with bright fluorescence, narrow emission, broad UV excitation and high photostability [43]. Ninety percent of QDs produced are used for light-emitting diode or organic light-emitting diode while 10% are used for imaging purposes [44].

Toxicity of nanoparticles

A recent study in Poland has shown that short term exposure to graphene oxide induces oxidative stress and DNA damage in some insects. They also found numerous degenerative changes in the cells of the gut and testis of Acheta domesticus ten days after applying graphene oxide [45]. Although, fullerene has exceptional antioxidant capacity which has made it a promising core ingredient in many dermatological and skin care products, it may be toxic to skin cells at high doses and with longer exposure time [46].The cytoxicity of carbon nanotubes is affected by its surface chemistry and size with shorter carbon nanotubes being less toxic than longer ones. Cells exposed to carbon nanotubes undergo oxidative stress which leads to inflammation and cytotoxicity at higher levels. Even when they don’t cause lung inflammation or tissue damage, they may alter immune function [19]. TiO2 nanoparticles have been reported to be genotoxic, carcinogenic and phototoxic [47]. TiO2 nanoparticles may induce oxidative DNA damage, lipid peroxidation, and increased hydrogen peroxide [48].

Nanoparticles In Biosolids

Background

About 7 million tonnes of biosolids are produced by WWTPs in the United States alone with about 60% applied on agricultural lands as organic fertilizer [49]. Biosolids contain nutrients and organic matter which may be used to enhance soil fertility and crop yield [50, 51]. Land application of biosolids is also a means of disposal of sewage sludge produced at WWTPs [52].

Biosolids are useful as a low-grade fertilizer and soil amendment to improve soil chemical and physical properties [53]. Biosolids are especially rich in phosphorus, have potentials for sustainable nutrient management and can be used to reduce exploitation of nonrenewable phosphorus resources such as phosphate rock [54,55]. Biosolids also provides a slow release source of nitrogen from the mineralization of organic matter [56]. Biosolids application produced greater NO3–N concentrations than N fertilizer in the 30–60 and 60–90 cm depths for the dryland no-till wheat (Triticum aestivum, L.)–fallow rotation [57].

Fate and Transport of Nanoparticles in Biosolids

Despite the beneficial effects of biosolids, excessive application rates may be harmful to the environment leading to regulation of biosolids by governing agencies [58]. Biosolids are regulated based on their biological content into class A if pathogens are completely undetectable or class B for higher detectable pathogens [58]. Class A is regulated and restricted to use in lawns, home gardens, or other types of land, or bagged for sale, or land application while class B is used for other applications [59]. However, there are other contaminants of emerging concern that should be considered during regulation which includes nanoparticles and pharmaceuticals.

Land application of biosolids is one way nanoparticles are released into the environment especially in agriculture where biosolids are used as organic fertilizers. Silver nanoparticles have been detected in the final stage sewage sludge Figure 1 of a municipal WWTP [60]. Even though a fraction of nanoparticles may be removed by the treatment, a significant amount is retained in the biosolids produced from sludge [61,62]. Titanium-containing nanoparticles between 50 nm and 250 nm in diameter were identified in soils with long term biosolids application in the United States [63].

Effect of nanoparticles on soil health

Soil health has been defined as “the capacity of soil to function as a living system, with ecosystem and land use boundaries, to sustain plant and animal productivity, maintain or enhance water and air quality, and promote plant and animal health. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots; recycle essential plant nutrients; improve soil structure with positive repercussions for soil water and nutrient holding capacity, and ultimately improve crop production” [64]. 

[65]. proposed that soil health is dependent on the maintenance of four major functions: carbon transformations; nutrient cycles; soil structure maintenance; and the regulation of pests and diseases. They explained that each of these functions is manifested as an aggregate of a variety of biological processes provided by a diversity of interacting soil organisms under the influence of the abiotic soil environment. 

Indicators of soil health

A combination of soil physical, chemical and biological properties Figure 2 can be used as indicators of soil health. For example, soil physical properties such as soil texture, aggregation, moisture, porosity, and bulk density; chemical properties such as total C and N, mineral nutrients, organic matter, cation exchange capacity (CEC); and soil biological properties such as microbial biomass C and N, biodiversity, soil enzymes, soil respiration, in addition to macro and mesofauna can be used [66]. Biological indicators are central to soil health because they can influence both chemical and physical properties of the soil.

Soil organisms are involved in nutrient mineralization and availability. Macro and mesofauna may also influence physical properties such as porosity, aeration and water infiltration. For example, earthworms can modify soil structure and enhance nutrient availability. Estimation of microbial biomass and activity may provide information of potential nutrient status of the soil. Soil organic matter is an important component of the soil which determines soil productivity but mineralization of soil organic matter may be greatly reduced in the absence of soil microorganisms. Hence, microbial activity is an important soil health indicator.

[2] Studied the effect of metal nanoparticles in biosolids on soil microbial community. Results indicate that ZnO and zerovalent Cu nanoparticles were not toxic to soil bacterial community while Ag nanoparticles and TiO2 (both anatase and rutile phase) in biosolids changed the bacterial richness and composition in wavering pattern as a function of time. This shows that the effect of nanoparticles on soil microbes depend on type of nanoparticle. The antimicrobial effect of carbon nanotubes or graphene oxide on gram-positive bacteria has been reported [67]. The antimicrobial effect of some nanoparticles may affect plant-microbe relationships which have impact on plant nutrition and soil fertility. For example, CeO2 nanoparticle dramatically reduced levels of nitrogen fixing bacteria within root nodules on soybeans thereby reducing nitrogen fixation rates [68].

A previous study tested the effect of nanoparticles in biosolids on soil microbial community and results showed that Ag nanoparticles also caused a reduction in microbial biomass and changes in microbial activity probably due to Ag+ released from partially sulfidized silver nanoparticles. The magnitude of the AgNO3 treatment effect on microbial abundance, community composition, and function was consistently equal to or less than the effects of silver nanoparticle treatment [69]. Unlike the first day, differences in microbial community structure were not detected after 50 days, suggesting that a period of aging of nanoparticles in either sewage sludge and/or soils may cause transformations that render the potential toxic effects minimal. A recent study showed that there were no differences in total leaching rates between treatments of Zn or Ag added to WWTP as nanoparticles or metal salt forms. The response of the soil microbial community to metal nanoparticles or metal salts was also very similar showing that the size of particles did not increase their toxicity or their leachability [70].

Many studies have used earthworms as indicators of soil health [71]. In their review on the effect of nanoparticles on earthworms in the soil, [72]. Explained that several studies have shown that the effect of nanomaterials on growth and survival of adult earthworms is negligible while some other studies reported that the reproductive activity of earthworms may be reduced by nanomaterials. However, it’s not clear if these tests are conducted with nanoparticles in biosolids. A past study has reported 100% mortality of earthworms in mine tailing soil amended with biosolids but could not identify the component that was toxic to the earthworms [73]. In the study, the addition of biosolids to mine tailing soil almost doubled plant biomass production and increased carbon substrate utilisation compared to untreated stockpiled or unmodified soils.

On the contrary, in another study, all of the adult earthworms survived in the biosolids amended soils at all concentrations that were aged for 2 weeks; while only 20% of the adults survived in the soil amended with the highest concentration of biosolids and aged for 8 weeks [74]. This suggests there may be chemical transformations within biosolids with longer aging time [75]. Reported that 97.5% of earthworms in a low organic matter soil survived, and the survival of the earthworms was not significantly affected by the addition of biosolids although biosolids reduced the gain in mass of earthworms. This is different from the results of yet another study that reported that biosolids enhanced the biomass of earthworms though the earthworms accumulated copper [76].

Effect of nanoparticles on crop growth

Several studies have shown that nanoparticles can be taken up directly by plants [77, 78], and translocated to the edible parts of the mustard plant (Brassica juncea) [79]. This indicates potential contamination of the food chain for both animals and humans. However, studies have reported positive and negative effects of nanoparticles Table 2 on plant growth and development [80].

Effect of nanoparticles on plant growth

The effect of nanoparticles on plant growth depends on the plant spp, type of nanoparticle, its mode and dose of application [80, 81]. Reported that the majority of the work on nanoparticles suggests low to moderate overall phytotoxicity in terrestrial plant species. [82]. explained that nanoparticles can cause phytotoxicity through dissolution and release of toxic ions, production of excess reactive oxygen species (ROS) through redox cycling, binding interactions and oxidation of biomolecules.

It has been reported that silver nanoparticles had a toxic effect on rice seedlings and the effect was dependent on size and dose of silver nanoparticles. Increasing the silver nanoparticle concentration over the range of 0.1 to 1000mgL-1 and increasing the size of the silver nanoparticles over the 20–150nm diameter range increased the inhibition effect upon seed germination and seedling growth [8]. The size and dose of nanoparticles play an important role in their behavior, reactivity and toxicity [83].

Though the addition of ZnO nanoparticles to the soil at a concentration of 500 mg kg-1 did not significantly affect the growth of maize, it inhibited root AM infection and plant phosphorus uptake [84]. At a concentration of 3000 mg kg-1, ZnO nanoparticle significantly inhibited the growth of soybean plants and also inhibited arbuscular mycorrhizal (AM) colonization in soybean roots at concentrations from 2000 mg kg-1 and higher [85]. The AM inhibitory effect of ZnO nanoparticles raised suggestions about its potential to be used in plant fungal control strategies. A study revealed that ZnO nanoparticles inhibited growth of fungal plant pathogens such as Fusarium graminearum in a mung bean broth agar and in sand [86].

However, the addition of phosphorus and inoculation of AM fungi reduced the bioavailability of Zn from ZnO nanoparticles which led to a reduction in the translocation and accumulation of Zn in maize shoots [84]. This suggests that P and AM fungi can be used to reduce plant uptake and ameliorate the effects of ZnO nanoparticles. A previous study evaluated the bioavailability of Zn in ZnO nanoparticles and effect on plant growth of maize plants [87]. Results show that the effect of ZnO nanoparticles on maize growth and nutrition, photosynthetic pigments, and root activity (dehydrogenase) was dependent on dose. At concentrations between 100 and 200 mg kg-1, the effect of nanoparticles was stimulatory; neutral at 400 mg/kg, and toxic between 800 and 3200 mg kg-1. Toxicity of ZnO nanoparticles may be higher than bulk or soluble Zn because the dissolved Zn2+ from ZnO nanoparticles may make a dominant contribution to their phytotoxicity [87].

Nanoparticles also have some beneficial impacts on plant growth. Graphene quantum dots enhanced the growth rate in coriander and garlic plants when the seeds were treated with graphene quantum dots [9]. Tomato seeds exposed to carbon nanotubes had faster germination rates and higher plant biomass production. Faster germination rate of seeds was attributed to the ability of carbon nanotubes to penetrate thick seed coat and support water uptake inside seeds [88].

Nano-SiO2 enhanced seed germination and stimulated the antioxidant system of squash under NaCl stress [7]. Nano-SiO2 enhances plant growth and development by increasing gas exchange and chlorophyll fluorescence parameters, such as net photosynthetic rate, transpiration rate, stomatal conductance, effective photochemical efficiency, actual photochemical efficiency and electron transport rate [7]. It has also been reported that silica coated with quantum dots promoted root growth of rice plants [89].

Titanium dioxide (TiO2) nanoparticles stimulate carbohydrate production and increases rate of photosynthesis in plants [90]. It has been shown to increase plant growth of wheat and enhance radicle and plumule growth of canola seedlings [90, 92]. The effect of TiO2 nanoparticles may be due to its role in controlling enzymes involved in the metabolism of nitrogen. These enzymes help plants to absorb nitrate and also aids in the conversion of inorganic nitrogen to organic nitrogen [93].

Conclusion

Although, the application of nanotechnology in fields like medicine, pharmacy could be lifesaving, elevated levels of nanoparticles in the environment may not be good for public health. The detection of nanoparticles in biosolids indicates that increasing production of nanoparticles has released them beyond the boundaries where they are needed. This does not however mean we should stop land application of biosolids which provides cheap source of nutrients and organic matter for good soil health and crop growth. There may be the need to develop more efficient treatment processes at WWTPs to increase removal of these contaminants of emerging concern before land application. Regulations also need to be modified to include allowable levels of nanoparticles in biosolids before land application. However, studies have shown that effect of nanoparticles on crop growth depend on plant species, type of nanoparticles and dose applied. More studies are needed to determine threshold levels for land application of these nanomaterials for different crops in biosolids amended soils. The antimicrobial effect of some nanoparticles may also affect plant-microbe relationships that promote soil fertility and crop growth. Hence, these nanoparticles need to be properly identified and regulated before land application of biosolids.

  1. Dawson, NG (2008) Sweating the small stuff: Environmental risk and nanotechnology Bioscience 58: 690.Link: https://goo.gl/ZImQlH
  2. Shah V, Jones J, Dickman J, Greenman S (2014) Response of soil bacterial community to metal nanoparticles in biosolids J Haz Mater 274: 399–403. Link: https://goo.gl/ewuXud
  3. Kiser MA, Westerhoff P, Benn T, Wang Y, Perez-Rivera J, et al. (2009) Titanium nanomaterial removal and release from wastewater treatment plants, Environ. Sci Technol 43: 6757–6793. Link: https://goo.gl/UWcF9u
  4. Gottschalk F, Nowack, B (2011) the release of engineered nanomaterials to the environment. J Environ Monitor 13: 1145–1155.Link: https://goo.gl/zeX4ZA
  5. Westerhoff P, Song G, Hristovski K, Kiser MA (2011) Occurrence and removal of titanium at full scale wastewater treatment plants: implications for TiO2 nano-materials. J Environ Monitor 23: 1195–1204. Link: https://goo.gl/7Y3tUe
  6. Semblante GU, Hai FI, Huang X, Ball AS, Price WE et al. (2015) Trace organic contaminants in biosolids: Impact of conventional wastewater and sludge processing technologies and emerging alternatives. J Haz Mater 300: 1-17. Link: https://goo.gl/Wv5W6D
  7. Siddiqui MH, Al-Whaibi MH, Faisal M, Al Sahli AA (2014) Nano-silicon dioxide mitigates the adverse effects of salt stress on Cucurbita pepo L. Environ Toxicol Chem 33: 2429– 2437. doi:10.1002/etc.2697. Link: https://goo.gl/gRKHxb
  8. Thuesombat P, Hannongbua S, Akasit S, Chadchawan S. (2014) Effect of silver nanoparticles on rice (Oryza sativa L. cv. KDML 105) seed germination and seedling growth. Ecotoxicol Environ Saf 104: 302–309. Link: https://goo.gl/AJFZ0F
  9. Chakravarty D, Erande M, Late DJ (2015). Graphene quantum dots as enhanced plant growth regulators: Effects on coriander and garlic plants. J Sci Food Agric 95: 2772-2778. Link: https://goo.gl/7YoeEv
  10. Jacobs LW, McCreary DS (2001) Utilizing biosolids on agricultural lands, Ext. Bull. E-2871. Link: https://goo.gl/9JViGa
  11. Bhusha B (2004) Introduction to nanotechnology, in: Bharat Bhushan (Ed.), Springer Handbook of Nanotechnology, Springer-Verlag, Berlin Heidelberg 1–13. Link: https://goo.gl/A7CQVt
  12. Sanchez F, Sobolev K (2010) Nanotechnology in concrete. A review, Constr. Build.Mater 24: 2060–2071. Link: https://goo.gl/RHnxN8
  13. Bhatia S. (2016). Nanoparticles Types, Classification, Characterization, Fabrication Methods and Drug Delivery Applications. In Natural Polymer Drug Delivery Systems, Springer International Publishing Switzerland. DOI 10.1007/978-3-319-41129-3_2. Link: https://goo.gl/nc9BMD
  14. Contreras JE, Rodriguez EA, Taha-Tijerina J. (2017) Nanotechnology applications for electrical transformers—A review. Electric Power Systems Research 143: 573-584. DOI: 10.1016/j.epsr.2016.10.058. Link: https://goo.gl/eu8La3
  15. Garimella R, Eltorai AE (2017). Nanotechnology in orthopedics. J Orthopaedics 14: 30-33. Link: https://goo.gl/zJoKaU
  16. Sharan J, Singh S, Lale SV, Mishra M, Koul V et al. (2017). Applications of nanomaterials in dental science: A review. (2017) J Nanosci Nanotechnol 17 2235-2255. Link: https://goo.gl/3MwbwU
  17. Hussain S (2016). Nanomedicine for treatment of lung cancer. Adv Experimental Medicine Biol 890: 137-147. Link: https://goo.gl/znCY2m
  18. Piperigkou Z, Karamanou K, Engin AB, Gialeli C, Docea AO, et al. (2016). Emerging aspects of nanotoxicology in health and disease: From agriculture and food sector to cancer therapeutics. Food Chem Toxicol 91: 42-57. Link: https://goo.gl/qCjbXR
  19. Wang P, Lombi E, Zhao FJ, Kopittke PM (2016a). Nanotechnology: A New Opportunity in Plant Sciences. (2016) Trends Plant Sci 21: 699-712. Link: https://goo.gl/j97gEF
  20. Chhipa H. (2017) Nanofertilizers and nanopesticides for agriculture. Environ Chem Letters 15: 15-22. Link: https://goo.gl/jkDEhJ
  21. Cheng HN, Klasson KT, Asakura T, Wu Q (2016). Nanotechnology in agriculture. ACS Symposium Series 1224: 233-242. Link: https://goo.gl/qsz7MX
  22. Srinivas K (2016). Sustainable agriculture based on nanotechnology. RES J PHARM BIOL CHEM SCI.7 (5):1681-1689. Link
  23. Hassan S (2015). A Review on Nanoparticles: Their Synthesis and Types. Res J Recent Sci 4:1-3. Link
  24. Jha AK, Prasad K (2010). Green Synthesis of Silver Nanoparticles Using Cycas Leaf. Int J Green Nanotechnol: Physics and Chemistry 1: 110-117. Link: https://goo.gl/0zYLny
  25. Park K, Seo D, Lee J (2008) Conductivity of Silver Paste Prepared from Nanoparticles. Colloids and Surfaces A, 313: 351-354. Link: https://goo.gl/A91ktd
  26. Sharma VK, Ria AY, Lin Y (2009). Adv Colloid Interface Sci 145: 83-96. Link: https://goo.gl/oBCwuu
  27. Siddiqui M, Al-Whaibi H (2013) Role of nano-SiO2 in germination of tomato (Lycopersicum esculentum).Saudi J Biol Sci21: 13-17. Link: https://goo.gl/mBofeM  
  28. Nair R, Varghese SH, Nair BG, Maekawa T, Yoshida Y et al. (2010) Nanoparticulate Material Delivery to Plants. Plant Sci 179: 154-163. Link: https://goo.gl/w09yx9
  29. Prow TW, Grice JE, Lin L, Faye R, Butler M et al. (2011) Nanoparticles and Microparticles for Skin Drug Delivery. Advanced Drug Delivery Reviews 63:470-49.Link: https://goo.gl/Yhfexn
  30. Tomar A, Garg G (2013) Short Review on Application of Gold Nanoparticles. Global J Pharmacol 7: 34-38. Link: https://goo.gl/vJAEVo
  31. Chaudhary S, Umar A, Mehta SK (2016). Selenium nanomaterials: An overview of recent developments in synthesis, properties and potential applications. Progress Mater Sci 83: 270-329. Link: https://goo.gl/V6f3rc
  32. Harris PJ (2009). Carbon Nanotube Science - Synthesis, Properties, and Applications. Cambridge Univ. Press, Cambridge. Link: https://goo.gl/TLe8U7
  33. De Volder MF, Tawfick SH, Baughman RH, John Hart AJ (2013) Carbon Nanotubes: Present and Future Commercial Applications. Science 339: 535-539. Link: https://goo.gl/69pJdh
  34. Gonzalez KA, Wilson LJ, Wu W, Nancollas GH. (2002)Synthesis and in vitro characterization of a tissue-selective fullerene: Vectoring C(60)(OH)(16)AMBP to mineralized bone. Bioorg Med Chem 10: 1991-7. Link: https://goo.gl/TYkW2x
  35. Bosi S, Da Ros T, Spalluto G, Prato M (2003). Fullerene derivatives: an attractive tool for biological applications. Med Chem 38:913-23. Link: https://goo.gl/fj10ib
  36. Partha R, Mitchell LR, Lyon JL, Joshi PP, Conyers JL. (2008) Buckysomes: fullerene-based nanocarriers for hydrophobic molecule delivery. ACS Nano 2:1950-8. Link: https://goo.gl/MeXctj
  37. Khaydarov R, Khaydarov R, Gapurova O (2010). Application of Carbon Nanoparticles for Water Treatment. Editors, Miroslava Václavíková, Ksenija Vitale, Georgios P. Gallios,Lucia Ivaničová. Water Treatment Technologies for the Removal of High-Toxicity Pollutants. Part of the series NATO Science for Peace and Security Series C: Environmental Security 253-258. Springer Netherlands. Link: https://goo.gl/G7QhBg
  38. Mottier A, Mouchet L, Pinelli E, Gauthier, L, Flahaut E (2017) Environmental impact of engineered carbon nanoparticles: from releases to effects on the aquatic biota, Current Opinion in Biotechnology 46:1-6 Link: https://goo.gl/mNWm3P
  39. Masood F (2016) Polymeric nanoparticles for targeted drug delivery system for cancer therapy, Materials Science and Engineering C 60: 569-578. Link: https://goo.gl/c7mjpq
  40. Bani BL, Fattahi P, Brown JL. (2016) Polymeric nanoparticles: The future of nanomedicine. WIREs Nanomed Nanobiotechnol 8: 271–299. Link: https://goo.gl/J3quQ9
  41. Rocha TL, Mestre NC, Sabóia-Morais SM, Bebianno MJ (2017) Environmental behaviour and ecotoxicity of quantum dots at various trophic levels: A review. Environ Int 98: 1-17. DOI: 10.1016/j.envint.2016.09.021. Link: https://goo.gl/Ds0I39
  42. Reed MA, Randall JN, Aggarwal RJ, Matyi RJ, Moore TM et al. (1988). Observation of discrete electronic states in a zero-dimensional semiconductor nanostructure. Phys. Rev. Lett 60: 535–537. Link: https://goo.gl/Tur7RC
  43. Nahar M, Dutta T, Murugesan S, Asthana A, Mishra D, et al. (2006) Functional polymeric nanoparticles: an efficient and promising tool for active delivery of bioactives. Crit Rev Ther Drug Carrier Syst 23: 259–318. Link: https://goo.gl/ziUrWO
  44. Piccinno F, Gottschalk F, Seeger S, Nowack B, (2012). Industrial production quantities and uses of ten engineered nanomaterials in Europe and the world. J Nanopart Res 14: 1109. Link: https://goo.gl/Jnwa2L
  45. Dziewięcka M, Karpeta-Kaczmarek J, Augustyniak M, Rost-Roszkowska M (2017). Short-term in vivo exposure to graphene oxide can cause damage to the gut and testis. J Haz Mater 328: 80-89. Link: https://goo.gl/nU6iq7
  46. Mousavi SZ, Nafisi S, Maibach, HI (2017) Fullerene nanoparticle in dermatological and cosmetic applications, Nanomedicine: Nanotechnology, Biology and Medicine 13: 1071-1087. Link: https://goo.gl/DYR9Si
  47. Iavicoli I, Leso V, Fontana L, Bergamaschi A (2011) Toxicological effects of titanium dioxide nanoparticles: A review of in vitro mammalian studies. Eur Rev Med Pharmacol Sci 15: 481–508. Link: https://goo.gl/EbZrFe
  48. Park EJ, Yi J, Chung KH, Ryu DY, Choi J, et al. (2008) Oxidative stress and apoptosis induced by titanium dioxide nanoparticles in cultured BEAS-2B cells. Toxicology Letters.180: 222–229. Link: https://goo.gl/iK1y0N
  49. United States Environmental Protection Agency, USEPA (2003) Control of Pathogens and vector attraction in sewage sludge, EPA 625-R-92-013, United States Environmental Protection Agency, Washington DC. Link: https://goo.gl/rBYU2V
  50. Kim KR, Owens G (2010).Potential for enhanced phytoremediation of landfills using biosolids - A review. J Environ Manage 91: 791-797. Link: https://goo.gl/mMLj8n
  51. Shargil D, Gerstl Z, Fine P, Nitsan I, Kurtzman D. (2015) Impact of biosolids and wastewater effluent application to agricultural land on steroidal hormone content in lettuce plants. Sci Total Environ 505: 357-366. Link: https://goo.gl/TKOqj8
  52. Li X, Brown, DG, Zhang W (2007) Stabilization of biosolids with nanoscale zerovalent iron (nZVI), J Nanopart Res 9: 233–243. Link: https://goo.gl/Rs6X47
  53. Elliott HA, O'Connor GA (2007) Phosphorus management for sustainable biosolids recycling in the United States. Soil Biol Biochem 39: 1318-1327. Link: https://goo.gl/pvwqcz
  54. Steen I (1998) Phosphorus recovery — Phosphorus availability in the 21st century. Management of a non-renewable resource. Phosphorus Potassium 217. Link: https://goo.gl/ds3by0
  55. Clarke BO, Smith SR (2011) Review of 'emerging' organic contaminants in biosolids and assessment of international research priorities for the agricultural use of biosolids. Environ Int 37: 226-247. Link: https://goo.gl/uIEgff
  56. Barbarick KA, Lerch RN, Utschig JM, Westfall DG, Follett RH, et al. (1992). Eight years of application of biosolids to dryland winter wheat. In: Colorado Agricultural Experiment Station Technical Bulletin TB92-1. Link: https://goo.gl/0a5809
  57. Barbarick KA, Ippolito JA, McDaniel J, Hansen NC, Peterson GA. (2012) Biosolids application to no-till dryland agroecosystems. Agric Ecosystems Environ. 150: 72-81. Link: https://goo.gl/qGU47K
  58. McCall CA, Jordan KS, Habash MB, Dunfield KE. (2015) Monitoring Bacteroides spp. markers, nutrients, metals and Escherichia coli in soil and leachate after land application of three types of municipal biosolids. Water Res 70: 255-265. Link: https://goo.gl/SrxW2E
  59. Lu Q, He ZL, Stoffella PJ (2012) Land Application of Biosolids in the USA: A Review. Applied and Environmental Soil Science Volume 2012, Article ID 201462, doi:10.1155/2012/201462. Link: https://goo.gl/p7VSvv
  60. Kim B, Park CS, Murayama M, Hochella MF (2010) Discovery and characterization of silver sulfide nanoparticles in final sewage sludge products. Environ Sci Technol 44: 7509–7514. Link: https://goo.gl/OS5yfM
  61. Rottman J, Shadman F, Sierra-Alvarez R (2012). Interactions of inorganic oxide nanoparticles with sewage biosolids, Water Sci Technol. 66:1821–1827. Link: https://goo.gl/RzB8U2
  62. Wang Y, WesterhoffP, Hristovski KD (2012) Fate and biological effects of silver, titanium dioxide, and C60 (fullerene) nanomaterials during simulated wastewater treatment processes. J Haz Mater 201-202: 16-22. Link: https://goo.gl/nySwBX
  63. P, Hristovski KD (2012) Fate and biological effects of silver, titanium dioxide, and C 60 (fullerene) nanomaterials during simulated wastewater treatment processes. J Haz Mater 201-202: 16-22. Link: https://goo.gl/nyvO51
  64. Yang Y, Wang Y, Westerhoff P, Hristovski K, Jin VL et al. (2014) Metal and nanoparticle occurrence in biosolid-amended soils. Sci Total Environ 485-486: 441-449. Link: https://goo.gl/Npl66g
  65. FAO (2008) An international technical workshop Investing in sustainable crop intensification The case for improving soil health. Integrated Crop Management Vol.6-2008. FAO Rome: 22-24 July 2008. Link: https://goo.gl/YbJqw1
  66. Kibblewhite M, Ritz K, Swift M (2008). Soil health in agricultural systems. Philosophical Transactions of the Royal Society B. Biological Sciences 363: 685–701.Link: https://goo.gl/X8A0OL
  67. Cardoso EJ, Vasconcellos RL, Marina YH, Santos CA, Alves PR, et al (2013) Soil health: looking for suitable indicators. What should be considered to assess the effects of use and management on soil health? Sci. agric 70(4): 274-289.Link: https://goo.gl/IgzmGx
  68. Brandeburová P, Bírošová L, Vojs M, Kromka A, Gál M, et al (2017) The influence of selected nanomaterials on microorganisms. Monatshefte fur Chemie, pp. 1-6: 525–530 Link: https://goo.gl/Kts4Ad
  69. Priester JH, Ge Y, Mielke RE, Horst AM, Moritz SC, et al (2012) Soybean susceptibility to manufactured nanomaterials with evidence for food quality and soil fertility interruption. PNAS 109:E2451–E2456. Link: https://goo.gl/8e7mjR
  70. Colman BP, Arnaout CL, Anciaux S, Gunsch CK, Hochella MF et al. (2013) Low Concentrations of Silver Nanoparticles in Biosolids Cause Adverse Ecosystem Responses under Realistic Field Scenario. PLoS ONE 8:Link: https://goo.gl/ZqfVBe
  71. Durenkamp M, Pawlett M, Ritz K, Harris JA, Neal AL et al. (2016) Nanoparticles within WWTP sludges have minimal impact on leachate quality and soil microbial community structure and function. Environ Pollut 211:399-405. Link: https://goo.gl/pLqVa7
  72. Rousseau GX, dos S. Silva PR, de Carvalho CJ (2010) Earthworms, ants and other arthropods as soil health indicators in traditional and no-fire agro-ecosystems from Eastern Brazilian Amazonia. Acta Zoológica Mexicana (n.s.). Número Especial 2: 117-134. Link: https://goo.gl/0SQPm5
  73. Kwak JI, a Y (2015) Ecotoxicological Effects of Nanomaterials on Earthworms: A Review. Human and Ecological Risk Assessment: An International Journal  21: 1566-1575. Link: https://goo.gl/EdJAN8
  74. Waterhouse BR, Boyer S, Adair, KL, Wratten SD (2014) Using municipal biosolids in ecological restoration: What is good for plants and soil may not be good for endemic earthworms. Ecological Engineering 70: 414–421. Link: https://goo.gl/kXMDlu
  75. Kinney CA, Campbell BR, Thompson R, Furlong ET, Kolpin DW (2012) Earthworm bioassays and seedling emergence for monitoring toxicity, aging and bioaccumulation of anthropogenic waste indicator compounds in biosolids-amended soil. SciTotal Environ 433: 507-515. Link: https://goo.gl/p0A77h
  76. McDaniel JP, Stromberger ME, Barbarick KA, Cranshaw W. (2013) Survival of Aporrectodea caliginosa and its effects on nutrient availability in biosolids amended soil. Applied Soil Ecol 71: 1-6. Link: https://goo.gl/zDn2Lq
  77. Adair KL, Wratten S, Barnes AM, Waterhouse BR, Smith M (2014) Effects of biosolids on biodiesel crop yield and belowground communities. Ecological Engineering 68: 270-278. Link: https://goo.gl/PHO7Qn
  78. Zhu H, Han J, Xiao JQ, Jin Y (2008) Uptake, translocation, and accumulation of manufactured iron oxide nanoparticles by pumpkin plants. J Environ Monit 10:713–717. Link: https://goo.gl/7Frm8Q
  79. Koo Y, Wang J, Zhang Q, Zhu H, Chehab EW et al. (2015) Fluorescence reports intact quantum dot uptake into roots and translocation to leaves of arabidopsis thaliana and subsequent ingestion by insect herbivores. Environ. Sci. Technol 49: 626–632.Link: https://goo.gl/vB6OsD
  80. Chen G, Qiu J, Liu Y, Jiang R, Cai S, et al. (2015) Carbon Nanotubes Act as Contaminant Carriers and Translocate within Plants. Scientific Reports: 5 art. No15682. Link: https://goo.gl/irtwk1
  81. Nair R (2016). Effects of nanoparticles on plant growth and development. Plant Nanotechnology: Principles and Practices 95-118. Link: https://goo.gl/6ZOTj5
  82. Servin AD, White JC (2016) Nanotechnology in agriculture: Next steps for understanding engineered nanoparticle exposure and risk. NanoImpact 1: 9-12. Link: https://goo.gl/oBZC8s
  83. Wang X, Yang X, Chen S, Li Q, Wang W, et al. (2016b) Corrigendum on Zinc Oxide Nanoparticles Affect Biomass Accumulation and Photosynthesis in Arabidopsis. Front Plant Sci 7: 559. Link:  https://goo.gl/WozWFe
  84. Farooqui A, Tabassum H, Ahmad A, Mabood A, Ahmad A et al. (2016). Role of nanoparticles in growth and development of plants: A review. Int J Pharm Bio Sci 7: 22 – 37. Link
  85. Jing XX, Su ZZ, Xing HE, Wang FY, Shi ZY, et al. (2016) Biological effects of ZnO nanoparticles as influenced by arbuscular mycorrhizal inoculation and phosphorus fertilization. (2016) Huanjing Kexue/Environmental Science 37: 3208-3215. Link
  86. Wang LH, Wang FY, Jing XX, Li S, Liu XQ (2015) Effect of ZnO nanoparticles and inoculation with arbuscular mycorrhizal fungus on growth and nutrient uptake of soybean. Shengtai Xuebao/ Acta Ecologica Sinica 35: 5254-5261. Link:
  87. Dimkpa CO, McLean JE, Britt DW, Anderson AJ. (2013) Antifungal activity of ZnO nanoparticles and their interactive effect with a biocontrol bacterium on growth antagonism of the plant pathogen Fusarium graminearum. BioMetals 26: 913-924. Link: https://goo.gl/guAsEZ
  88. Liu X, Wang F, Shi Z, Tong R, Shi X. (2015). Bioavailability of Zn in ZnO nanoparticle-spiked soil and the implications to maize plants. J Nanoparticle Res 17:11.Link: https://goo.gl/e7oqre
  89. Khodakovskaya M, Mahmood EM, Xu Y, Li Z, Watanabe F et al. (2009) Carbon nanotubes are able to penetrate plant seed coat and dramatically affect seed germination and plant growth. ACS Nano 3: 3221–3227. Link: https://goo.gl/W6fSsV
  90. Wang A, Zheng Y, Peng F (2014) Thickness-controllable silica coating of CdTe QDs by reverse Microemulsion method for the application in the growth of rice. J Spectrosc. Link: https://goo.gl/6FY3vV
  91. Chen H, Seiber JN, Hotze M. (2014) ACS select on nanotechnology in food and agriculture: A perspective on implications and applications. J Agri Food Chem 62: 1209-1212. Link: https://goo.gl/whrlJj
  92. Mahmoodzadeh H, Nabavi M, Kashefi H. (2013) Effect of nanoscale titanium dioxide particles on the germination and growth of canola (Brassica napus). J. Ornamental Hortic Plants 3: 25-32. Link: https://goo.gl/ye0uKr
  93. Jaberzadeh A, Moaveni P, Moghadam HR, Zahedi H (2013) Influence of bulk and nanoparticles titanium foliar application on some agronomic traits, seed gluten and starch contents of wheat subjected to water deficit stress. Not. Bot. Horti. Agrobo 41: 201-207. Link: https://goo.gl/j9eMQd
  94. Yang F, Hong F, You W, Liu C, Gao F, et al. (2006) Influence of nano-anatase TiO2 on the nitrogen metabolism of growing spinach. Biol Trace Elem Res 110: 179-190. Link: https://goo.gl/WVuSM1
  95. Rahmani F, Peymani A, Daneshvand E, Biparva P (2016) Impact of zinc oxide and copper oxide nanoparticles on physiological and molecular processes in Brassica napusL. Indian J. Plant Physiol 21: 122-128. Link: https://goo.gl/anwCLO
  96. Raliya R, Biswas P, Tarafdar JC (2015) TiO2 nanoparticle biosynthesis and its physiological effect on mung bean (Vigna radiata L.). Biotechnol Rep 5: 22-26. Link: https://goo.gl/ZgbMBZ
  97. Sabir S, Arshad M, Chaudhari SK (2014) Zinc Oxide Nanoparticles for Revolutionizing Agriculture: Synthesis and Applications. The Scientific World Journal, vol. 2014, Article ID 925494,doi:10.1155/2014/925494. Link: https://goo.gl/8zake6
  98. Sergey B, Mitchell LF, Jennifer S, Yaolin X, Yuping B et al. (2015) Developmental and reproductive effects of iron oxide nanoparticles in Arabidopsis thaliana. Int J Mol Sci 16: 24174–24193. Link
  99. Weir A, Westerhoff P, Fabricius L, von Goetz N (2012). Titanium Dioxide Nanoparticles in Food and Personal Care Products. Environ Sci Technol 46: 2242–2250.Link: https://goo.gl/TyD9kH
  100. Wu SY, an SS, Hulme J (2015) Current applications of graphene oxide in nanomedicine. Int J Nanomedicine 10:9–24.Link: https://goo.gl/xJMtPP
  101. Zhang Z, Tsai PC, Ramezanli T, Michniak-Kohn BB (2013). Polymeric nanoparticles-based topical delivery systems for the treatment of dermatological diseases. Wiley Interdisciplinary Rev Nanomedicine Nanobiotechnol 5: 205–218.Link: https://goo.gl/oNuldT
  102. Calabrese EJ, Baldwin LA (2001) U-shaped dose responses in biology, toxicology, and public health. Annu. Rev. Public Health 22: 15-33. Link: https://goo.gl/7uBWUG
  103. Chandra S, Kumar, A, Tomar, PK (2014) Synthesis and characterization of copper nanoparticles by reducing agent, J Saudi Chem Soc 18: 149-153. Link: https://goo.gl/HftfrQ
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