Nanomaterials (NMs), both natural and synthetic, are produced, transformed, and exported into our environment daily. Natural NMs annual flux to the environment is around 97% of the total and is ...significantly higher than synthetic NMs. However, synthetic NMs are considered to have a detrimental effect on the environment. The extensive usage of synthetic NMs in different fields, including chemical, engineering, electronics, and medicine, makes them susceptible to be discharged into the atmosphere, various water sources, soil, and landfill waste. As ever-larger quantities of NMs end up in our environment and start interacting with the biota, it is crucial to understand their behavior under various environmental conditions, their exposure pathway, and their health effects on human beings. This review paper comprises a large portion of the latest research on NMs and the environment. The article describes the natural and synthetic NMs, covering both incidental and engineered NMs and their behavior in the natural environment. The review includes a brief discussion on sampling strategies and various analytical tools to study NMs in complex environmental matrices. The interaction of NMs in natural environments and their pathway to human exposure has been summarized. The potential of NMs to impact human health has been elaborated. The nanotoxicological effect of NMs based on their inherent properties concerning to human health is also reviewed. The knowledge gaps and future research needs on NMs are reported. The findings in this paper will be a resource for researchers working on NMs all over the world to understand better the challenges associated with NMs in the natural environment and their human health effects.
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•The ubiquitous presence of natural and synthetic nanomaterials in the environment•Nanomaterials influence on the natural ecosystem.•Exposure pathways and life cycle of nanomaterials in the human body•Nanotoxicity of nanomaterials on human health
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In the race to enhance agricultural productivity, irrigation will become more dependent on poorly characterized and virtually unmonitored sources of water. Increased use of irrigation water has led ...to impaired water and soil quality in many areas. Historically, soil salinization and reduced crop productivity have been the primary focus of irrigation water quality. Recently, there is increasing evidence for the occurrence of geogenic contaminants in water. The appearance of trace elements and an increase in the use of wastewater has highlighted the vulnerability and complexities of the composition of irrigation water and its role in ensuring proper crop growth, and long-term food quality. Analytical capabilities of measuring vanishingly small concentrations of biologically-active organic contaminants, including steroid hormones, plasticizers, pharmaceuticals, and personal care products, in a variety of irrigation water sources provide the means to evaluate uptake and occurrence in crops but do not resolve questions related to food safety or human health effects. Natural and synthetic nanoparticles are now known to occur in many water sources, potentially altering plant growth and food standard. The rapidly changing quality of irrigation water urgently needs closer attention to understand and predict long-term effects on soils and food crops in an increasingly fresh-water stressed world.
Redox driven mobilization and plant uptake of contaminants under transiently saturated soil conditions need to be clarified to ensure food and water quality across different irrigation systems. We ...postulate that solid-phase iron reduction in anoxic microsites present in the rhizosphere of unsaturated soil is a key driver for mobilization and bioavailability of contaminants under nonflooded irrigation. To clarify this, two major crops, corn and soybean differing in iron uptake strategies, were grown in irrigated synthetic soil under semiarid conditions with gravimetric moisture content ∼12.5 ± 2.4%. 2-line ferrihydrite, which was coprecipitated with uranium and arsenic, served as the only iron source in soil. Irrespective of crop type, reduced iron was detected in pore water and postexperiment rhizosphere soil confirming ferrihydrite reduction. These results support the presence of localized anoxic microsites in the otherwise aerobic porous bulk soil causing reduction of ferrihydrite and concomitant increase in plant uptake of comobilized contaminants. Our findings indicate that reactive iron minerals undergo reductive dissolution inside anoxic microsites of primarily unsaturated soil, which may have implications on the mobility of trace element contaminants such as arsenic and uranium in irrigated unsaturated soils, accounting for 55% of the irrigated area in the US.
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IJS, KILJ, NUK, PNG, UL, UM
A four-decade dataset (1974–2013) of 107,823 nitrate samples in 25,993 wells from western and eastern parts of Nebraska was used to assess long-term trends of groundwater nitrate concentration and ...decadal changes in the extent of groundwater nitrate-contaminated areas (NO3-N ≥ 10 mg N/L) over the entire state. Spatial statistics and regressions were used to investigate the relationships between groundwater nitrate concentrations and several potential natural and anthropogenic factors, including soil drainage capacities, vadose zone characteristics, crop production areas, and irrigation systems. The results of this study show that there is no statistically significant trend in groundwater nitrate concentrations in western Nebraska, in contrast with the increasing trend (p < .05) to the east. The spatial extent and nitrate concentrations in contaminated groundwater in center pivot-irrigated areas was less than in gravity-irrigated areas. Areas with a thicker vadose zone and larger saturated thickness of the aquifer have relatively lower nitrate concentrations. The results of a classification and regression tree (CART) model indicate the difference in the influence of physical factors on groundwater nitrate concentrations between western and eastern Nebraska, namely that groundwater nitrate concentrations correspond with vadose zone thickness, effective hydraulic conductivity, and saturated thickness in the west, while in eastern Nebraska, concentrations are correlated with average percent sand in the topsoil (0–150 cm), well depth, and effective hydraulic conductivity.
•Groundwater nitrate concentrations in Nebraska have been increasing steadily over the last 40 years•Eastern Nebraska regions shows an increasing trend in groundwater nitrate contamination•Groundwater in western Nebraska lacks any definitive trend in nitrate contamination•Groundwater nitrate can be predicted by soil sand and organic matter, and is strongly correlated tovadose zone thickness
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Understanding transient nitrogen (N) storage and transformation in the deep vadose zone is critical for controlling groundwater contamination by nitrate. The occurrence of organic and inorganic forms ...of carbon (C) and nitrogen and their importance in the deep vadose zone is not well characterized due to difficulty in sampling and the limited number of studies. We sampled and characterized these pools beneath 27 croplands with different vadose zone thicknesses (6–45 m). We measured nitrate and ammonium in different depths for the 27 sites to evaluate inorganic N storage. We measured total Kjeldahl nitrogen (TKN), hot-water extractable organic carbon (EOC), soil organic carbon (SOC), and δ13C for two sites to understand the potential role of organic N and C pools in N transformations. Inorganic N stocks in the vadose zone were 21.7–1043.6 g m−2 across 27 sites; the thicker vadose zone significantly stored more inorganic N (p < 0.05). We observed significant reservoirs of TKN and SOC at depths, likely representing paleosols that may provide organic C and N to subsurface microbes. The occurrence of deep C and N needs to be addressed in future research on terrestrial C and N storage potential. The increase of ammonium and EOC and δ13C value in the proximity of these horizons is consistent with N mineralization. An increase of nitrate, concurrent with the sandy soil texture and the water-filled pore space (WFPS) of 78 %, suggests that deep vadose zone nitrification may be supported in vadose zones with organic-rich layers such as paleosol. A profile showing the decrease of nitrate concentrations, concurrent with the clay soil texture and the WFPS of 91 %, also suggests denitrification may be an important process. Our study shows that microbial N transformation may be possible even in deep vadose zone with co-occurrence of C and N sources and controlled by labile C availability and soil texture.
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•21.7–1043.6 g m−2 of inorganic N (nitrate and ammonium) was stored in vadose zone.•Thicker vadose zone sediments stored more inorganic N.•N transformation in deep vadose can occur with the presence of organic C.•Mineralization and nitrification occurred at the 19 m depth with sandy soil texture.•Denitrification occurred at the 12 m soil depth with clay soil texture.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The impact of commonly-used livestock antibiotics on soil nitrogen transformations under varying redox conditions is largely unknown. Soil column incubations were conducted using three livestock ...antibiotics (monensin, lincomycin and sulfamethazine) to better understand the fate of the antibiotics, their effect on nitrogen transformation, and their impact on soil microbial communities under aerobic, anoxic, and denitrifying conditions. While monensin was not recovered in the effluent, lincomycin and sulfamethazine concentrations decreased slightly during transport through the columns. Sorption, and to a limited extent degradation, are likely to be the primary processes leading to antibiotic attenuation during leaching. Antibiotics also affected microbial respiration and clearly impacted nitrogen transformation. The occurrence of the three antibiotics as a mixture, as well as the occurrence of lincomycin alone affected, by inhibiting any nitrite reduction, the denitrification process. Discontinuing antibiotics additions restored microbial denitrification. Metagenomic analysis indicated that Proteobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi were the predominant phyla observed throughout the study. Results suggested that episodic occurrence of antibiotics led to a temporal change in microbial community composition in the upper portion of the columns while only transient changes occurred in the lower portion. Thus, the occurrence of high concentrations of veterinary antibiotic residues could impact nitrogen cycling in soils receiving wastewater runoff or manure applications with potential longer-term microbial community changes possible at higher antibiotic concentrations.
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•Levels of oxygen impacted the fate of lincomycin, monensin, and sulfamethazine.•Lincomycin and sulfamethazine decreased during transport through the columns.•Impact on denitrification: Antibiotics' mix>Lincomycin>Sulfamethazine>Monensin.•Antibiotics determined a temporal change in microbial community composition.•Predominant phyla: Proteobacteria, Bacteroidetes, Actinobacteria, and Chloroflexi.
High concentrations of veterinary antibiotic residues in soils receiving wastewater runoff or manure applications impact the nitrogen cycling and modify the soil microbial community.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The occurrence and estimated concentration of twenty illicit and therapeutic pharmaceuticals and metabolites in surface waters influenced by wastewater treatment plant (WWTP) discharge and in ...wastewater effluents in Nebraska were determined using Polar Organic Chemical Integrative Samplers (POCIS). Samplers were installed in rivers upstream and downstream of treated WWTP discharge at four sites and in a discharge canal at a fifth location. Based on differences in estimated concentrations determined from pharmaceuticals recovered from POCIS, WWTP effluent was found to be a significant source of pharmaceutical loading to the receiving waters. Effluents from WWTPs with trickling filters or trickling filters in parallel with activated sludge resulted in the highest observed in-stream pharmaceutical concentrations. Azithromycin, caffeine, 1,7-dimethylzanthine, carbamazepine, cotinine, DEET, diphenhydramine, and sulfamethazine were detected at all locations. Methamphetamine, an illicit pharmaceutical, was detected at all but one of the sampling locations, representing only the second report of methamphetamine detected in WWTP effluent and in streams impacted by WWTP effluent.
Passive samplers were used to develop semi-quantitative estimates of pharmaceutical concentrations in receiving waters influenced by wastewater effluent.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Wastewater impoundments at concentrated animal feeding operations (CAFOs) represent a potential source of veterinary pharmaceuticals and steroid hormone contamination to shallow groundwater. This ...study investigates the occurrence of seventeen veterinary pharmaceuticals and thirteen steroid hormones and hormone metabolites in lagoons and adjacent groundwater at operating swine and beef cattle facilities. These sites were chosen because subsurface geology and previous monitoring of nitrate, ammonia and chloride levels in shallow ground water strongly indicated direct infiltration, and as such represent worst cases for ground water contamination by waste water. Pharmaceutical compounds detected in samples obtained from cattle facilities include sulfamerazine; sulfamethazine; erythromycin; monensin; tiamulin; and sulfathiazole. Lincomycin; ractopamine; sulfamethazine; sulfathiazole; erythromycin; tiamulin and sulfadimethoxine were detected in wastewater samples obtained from swine facilities. Steroid hormones were detected less frequently than veterinary pharmaceuticals in this study. Estrone, testosterone, 4-androstenedione, and androsterone were detected in wastewater impoundments at concentrations ranging from 30 to 3600
ng/L, while only estrone and testosterone were detected in groundwater samples at concentrations up to 390
ng/L. The co-occurrence of veterinary pharmaceutical and steroid hormone contamination in groundwater at these locations and the correlation between pharmaceutical occurrence in lagoon wastewater and hydraulically downgradient groundwater indicates that groundwater underlying some livestock wastewater impoundments is susceptible to contamination by veterinary pharmaceuticals and steroid hormones originating in wastewater lagoons.
► Wastewater and shallow groundwater at operating CAFOs was sampled for pharmaceuticals and steroids. ► Pharmaceuticals were detected in shallow groundwater at all facilities. ► Pharmaceuticals and steroids in groundwater imply wastewater contamination by lagoons.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
•Occurrence, removal of 43 pharmaceutical compounds at 4 WWTPs in the Hawaiian Islands•Impact of 8 soils types on the fate of compounds present in WWTPs' effluents•75% of investigated compounds were ...not detected in effluent.•Soil properties highly impacted sorption and degradation of selected compounds.•Steroids had the lowest leaching potential.
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The occurrence of pharmaceutical and steroid compounds in groundwater due to wastewater reuse has been reported and is of concern in tropical islands which primarily rely on groundwater. The objective of this study was to investigate the occurrence and removal of 43 pharmaceutical and steroid compounds detected in wastewater at four different wastewater treatment plants (WWTPs) in Hawai‘i and to understand their environmental behavior through tropical soils as the treated effluents are used in landscapes for irrigation. Eight soil sampling locations, collected at three different depths, representing the most common soil types in Hawai‘i and four WWTPs located across the major Hawaiian Islands were used. Disturbed soil samples were used to conduct the soil sorption and degradation studies and to estimate the leaching risk associated to the identified compounds. Quantification of selected compounds was conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS).
Among the investigated compounds, only ten were detected in the treated effluents at concentrations ranging from 0.004 to 0.900 μg L−1. Caffeine (64 μg L−1) and ibuprofen (96.5 μg L−1) showed the highest concentration in raw samples, while diphenhydramine (0.9 μg L−1) showed the highest concentration in treated effluent samples. Sulfamethoxazole showed the lowest removal (0–75%). Several pharmaceuticals showed consistently higher sorption capacity and longer persistency compared with steroids regardless of soil types and depths. Poamoho (Oxisol soil) and Waimānalo (Mollisol soil) showed the highest sorption capacity, while Waimea (Entisol soil) showed the lowest sorption capacity. Soil physico-chemical properties (i.e., clay content, level of organic carbon, and presence of metal oxide) and soil depth highly impacted the sorption behavior of the selected pharmaceutical compounds. In particular, the sorption capacity decreased with soil depth due to the higher level of organic carbon present in the first 30 cm compared with the deeper depths (60–90 cm).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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