The toxicological effect on pak choi of co-exposure to degradable and non-degradable microplastics with oxytetracycline in the soil.

Microplastics and antibiotics are emerging as ubiquitous contaminants in farmland soil, harming crop quality and yield, and thus threatening global food security and human health. However, few studies have examined the individual and joint effects of degradable and/or non-degradable microplastics and antibiotics on crop plants. This study examined the individual and joint effects of polyethylene (PE) and polylactic acid (PLA) microplastics and the antibiotic oxytetracycline (OTC) on pak choi by measuring its growth, photosynthesis, antioxidant enzyme activity, and metabolite levels. Microplastics and/or oxytetracycline adversely affected root weight, photosynthesis, and antioxidant enzyme (superoxide dismutase, catalase, and ascorbate peroxidase) activities. The levels of leaf metabolites were significantly altered, causing physiological changes. Biosynthesis of plant secondary metabolites and amino acids was altered, and plant hormones pathways were disrupted. Separately and together, OTC, PE, and PLA exerted phytotoxic and antagonistic effects on pak choi. Separately and together with OTC, degradable microplastics altered the soil properties, thus causing more severe impacts on plant performance than non-degradable microplastics. This study elucidates the effects on crop plants of toxicity caused by co-exposure to degradable or non-degradable microplastic and antibiotics contamination and suggests mechanisms.

Impact of polystyrene microplastics with combined contamination of norfloxacin and sulfadiazine on Chrysanthemum coronarium L.

Antibiotics and microplastics including nanoplastics are emerging contaminants which have become global environmental issues. The application of antibiotics along with microplastics in soil and their entrance in food chain may pose a major threat to human health. The single and combined exposure of polystyrene microplastic (MPS), norfloxacin (NF) and sulfadiazine (SFD) on Chrysanthemum coronarium L. a medicinal food crop, were investigated. Accumulation of nutrient element contents (Fe, Mn, Mg, Zn, K) differentially responded to the single or combined treatments compared to the control. Scanning electron microscopy and transmission electron microscopy analysis indicated that MPS, NF and SFD accumulated in roots, shoots, and leaves and affected their ultrastructure. Compared with that of the single contamination, the co-contamination of microplastics and antibiotics had a greater effect on leaf metabolites due to combination of multiple abiotic stresses. MPS, NF and SFD accumulated from roots and transported to shoots and leaves which ultimately impacts plant metabolites and, nutritional value. They subsequently impact agricultural sustainability and food safety of medicinal food plants. This investigation suggests the possible ecological risks of microplastics to medicinal food plants, especially in co-exposure with organic pollutants like antibiotics and help to reveal potential mechanisms of phytotoxicity of different antibiotics with polyethylene microplastic.

Phytotoxic effects on chloroplast and UHPLC-HRMS based untargeted metabolomic responses in Allium tuberosum Rottler ex Sprengel (Chinese leek) exposed to antibiotics.

Introduction of antibiotics into agricultural fields poses serious health risks to humans. This study investigated the uptake of antibiotics, their effects on metabolic pathways, and chloroplast structure changes of Allium tuberosum exposed to norfloxacin (NFL), oxytetracycline (OTC), and tetracycline (TC). Among all the antibiotic treatments, the highest accumulation of antibiotics in roots (4.15 mg/kg) and leaves (0.29 mg/kg) was TC, while in bulbs it was NFL (5.94 mg/kg). OTC was with the lowest accumulation in roots: 0.19 mg/kg, bulbs: 0.18 mg/kg, and leaves: 0.11 mg/kg. The number of mitochondira and the number of plastoglobulli increased. The chloroplast structure was disturbed under the stress of NFL, OTC, and TC. Disturbance in the chloroplast ultrastructure leads to altered chlorophyll fluorescence variables. Simultaneously, metabolomic profiling of leaves demonstrated that NFL stress regulated more of metabolic pathways than OTC and TC. Differences in metabolic pathways among the antibiotic treatments showed that each antibiotic has different impact even under the same experimental conditions. TC and NFL have more toxic effects than OTC antibiotic. Metabolic variations induced by antibiotics stress highlighted pools of metabolites that affect the metabolic activities, chlorophyll fluorescence, ultrastructural adjustments, and stimulate defensive impact in A. tubersoum. These findings provide an insight of metabolic destabilization as well as metabolic changes in defensive mechanism and stress response of A. tuberosum to different antibiotics.

Effects of antibiotics stress on growth variables, ultrastructure, and metabolite pattern of Brassica rapa ssp. chinensis.

Antibiotics frequently contaminate agricultural fields and through plant uptake enter into the food chain. This study aimed to explore the effects of antibiotics; tetracycline (TC), oxytetracycline (OTC) and norfloxacin (NF) on the growth, cell ultrastructure, and metabolite pattern of Brassica rapa ssp. chinensis. Oxytetracycline accumulated more than other antibiotics followed by TC and NF. Plant growth, chlorophyll fluorescence, and antioxidant activities were negatively affected under all antibiotic treatments. Ultrastructural investigation of mesophyll of leaves performed by transmission electron microscopy indicated that antibiotic stress caused the changes in thylakoid orientation, number of plastoglobuli, and starch grains. Identification of functional groups through Fourier transform infrared analysis indicated that carboxyl group, carbonate and ammonium ions are involved in the adsorption of antibiotics. The metabolic profiling of B. rapa leaves demonstrated that all of the antibiotics treatments distorted phenylalanine, tyrosine and tryptophan biosynthesis, d-glutamine and d-glutamate metabolism, alanine, aspartate and glutamate metabolism, phenylalanine metabolism and TCA cycle. Metabolic alterations as a result of antibiotics stress provide insights of metabolites that affect the physiological changes attributed to antibiotic stress. These results will improve the understanding of antibiotic contamination effects on plants.

Transport and retention of polymeric and other engineered nanoparticles in porous media.

Increasing applications of nanoparticles (NPs) in agriculture have raised potential risks to soil and aquatic ecosystems. A comparative study examining the transport of commonly used NPs in porous media is of critical significance for their application and regulation in agroecosystems. In this study, laboratory column leaching experiments were conducted to investigate the transport and retention of polysuccinimide NPs (PSI-NPs) in two saturated porous media with different grain sizes, as compared with multi-walled carbon nanotubes (MWCNTs), nano-Ag and nano-TiO2. Zeta potential of the NPs was negative at pH6.3 and decreased in an order of PSI-NPs > nano-TiO2 > MWCNTs > nano-Ag. The coarse and fine sands used in this study had negative charges with similar zeta potentials. The movement of NPs was affected by grain size, with larger sizes facilitating mobility while finer sizes favoring retention of NPs in the porous matrix. The retention profile significantly varied between the two sand columns, with more NPs transported to deeper layers in the coarse sand than the fine sand. The relative percentage of NPs detected in leachate was found to be positively correlated with the zeta potential of NPs (r = 0.931). Among the NPs, nano-Ag had the most negative zeta potential, and therefore was the most mobile, followed by MWCNTs and nano-TiO2. Having the least negative zeta potential, PSI-NPs had the lowest mobility, as compared with other NPs regardless of matrix grain size. This work reveals grain size and zeta potential of NPs are major factors that influence transport of NPs along the vertical porous profile, as well as demonstrating the relative unimportance of NP composition, which could serve as important guideline in nanomaterials application, risk assessment, and waste management in agroecosystems.

Study amino acid contents, plant growth variables and cell ultrastructural changes induced by cadmium stress between two contrasting cadmium accumulating cultivars of Brassica rapa ssp. chinensis L. (pak choi).

Cadmium (Cd) is an inauspicious abiotic traction that not only influences crop productivity and its growth parameters, but also has adverse effects on human health if these crops are consumed. Among crops, leafy vegetables which are the good source of mineral and vitamins accumulate more Cd than other vegetables. It is thus important to study photosynthetic variables, amino acid composition, and ultrastructural localization of Cd differences in response to Cd accumulation between two low and high Cd accumulating Brassica rapa ssp. chinensis L. (pak choi) cultivars, differing in Cd accumulation ability. Elevated Cd concentrations significantly lowered plant growth rate, biomass, leaf gas exchange and concentrations of amino acids collated to respective controls of both cultivars. Electron microscopy indicated that the impact of high Cd level on ultrastructure of leaf cells was associated to affecting cell functionalities, i.e. irregular cell wall, withdrawal of cell membrane, and chloroplast structure which has negative impact on photosynthetic activities, thus causing considerable plant growth suppression. Damage in root cells were observed in the form of enlargement of vacuole. The energy dispersive micro X-ray spectroscopy of both cultivars leaves indicated that cellular structure exhibited exudates of Cd-dense material. Ultrastructural damages and phytotoxicity were more pronounced in high accumulator cultivar as compared to the low accumulator cultivar. These findings are useful in determining the mechanisms of differential Cd-tolerance among cultivars with different Cd tolerance abilities at cellular level.

Biomass decaying and elemental release of aquatic macrophyte detritus in waterways of the Indian River Lagoon basin, South Florida, USA.

Decaying experiments of four major aquatic macrophyte detritus, namely cattail (Typha orientalis), water lettuce (Pistia stratiotes), hydrilla (Hydrilla verticillata) and maidencane (Panicum hemitomon), were conducted using the litterbag technique in the stormwater detention pond of South Florida, USA. Dry weight and chemical composition of remaining biomass were dynamically determined during the 185-day decay experiment. The results showed that decomposition rates (k), and the derived turnover (t50% and t95%) were species specific. The k values decreased in the order of hydrilla (0.0123 g day-1) > water lettuce (0.0082 g day-1) > maidencane (0.0049 g day-1) > cattail (0.0031 g day-1), whereas t50% and t95% varied in the reverse way. Biomass properties including concentrations of C, N, P, lignin, cellulose, hemicellulose, and the ratios of C/N, C/P, N/P and lignin/N affected decaying rate of the studied aquatic plants. The dry mass loss and concentrations of C, N, P, lead (Pb), chromium (Cr), copper (Cu), manganese (Mn), zinc (Zn), lignin, cellulose, hemicellulose and ratios C/N, C/P, N/P and Lignin/N of plant detritus were significantly affected by species, decaying time, and their interactions. However, the influence of species differences was greater than that of decaying time on those indexes. The estimated amounts (kg) of nutrients and metals released based on k values for the waterways of the IRL basin (water surface area 15.6 km2) were N 126.85 × 103, P 8.89 × 103, Zn 408.20, Pb 97.95, Cr 128.99, Mn 313.03, and Cu 82.40. Water lettuce contributed most, accounting for 52.13% N, 56.81% P, 74.95% Zn, 59.58% Pb, and 74.65% Mn, followed by hydrilla, cattail and maidencane. For Cr and Cu, cattail had the greatest contribution of 65.77% and 54.15%, respectively, followed by water lettuce, hydrilla and maidencane.

Spatial-temporal variations of dissolved organic nitrogen molecular composition in agricultural runoff water.

Leaching of dissolved organic nitrogen (DON) has been reported as a pathway of N loss from agriculture, but the molecular composition of DON in agricultural water is poorly understood. Runoff water samples were collected from citrus grove furrows (CGF), ditches (CGD) and pasture ditches (PD) in four seasons. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to investigate molecular composition of DON. Chemodiversity index of DON had spatiotemporal variations, while the molecular composition of total DON showed minimal variations, except for PD in November. Lignin derivatives constituted 61% of the total DON compounds. Relative abundance of aliphatic compounds, char and condensed aromatics of unique DON compounds varied spatiotemporally and had a significant correlation with DON concentration. Aromaticity index decreased from CGF to connected CGD, implying that photodegradation is possibly the dominant process that alters molecular composition of aquatic DON during the transport. Significant differences in unique DON composition between CGD and PD indicates that fertilization and land use affect DON composition. The information on molecular characterization of DON should be useful for tracking DON source and developing technologies to remove DON in the agricultural runoff water.

Impact of different feedstocks derived biochar amendment with cadmium low uptake affinity cultivar of pak choi (Brassica rapa ssb. chinensis L.) on phytoavoidation of Cd to reduce potential dietary toxicity.

Biochar has become eco-friendly amendment used for phytoavoidation with low cadmium (Cd) accumulating cultivars of crops to ensure food safety in Cd contaminated soils. In this study, biochar with different waste feedstock material were evaluated for their effectiveness on essential trace metals mobility, Cd bioavailability and its accumulation in two contrasting Cd accumulating cultivars of pak choi (Brassica rapa ssp. chinensis L.) grown in Cd contaminated Mollisol soil. A greenhouse experiment was conducted with plants grown in Cd contaminated soil that had been amended with biochar derived from barley straw, tomato green waste, chicken manure, duck manure and swine manure at application rate of 0%, 2.5% and 5.0% (w/w). The results showed that soil pH was significantly increased by all treatments. Biochar increased plant dry biomass, micronutrients bioavailability with significant differences in the Cd sorption capacity, with the effectiveness higher with increasing biochar application rate. However, tomato green waste (TGW) and chicken manure (CM) derived biochar were more effective than the other biochar in reducing Cd mobilization in soil by 35-54% and 26-43% and reduced its accumulation in shoots of pak choi cultivars by 34-76% and 33-72% in low Cd accumulator cultivar and 64-85% and 55-80% in high Cd accumulator cultivar than the control. Overall, results indicate that TGW and CM biochar can efficiently immobilize Cd, thereby reducing bioavailability in Cd contaminated Mollisol soil to ensure food safety.

Spatiotemporal change of phosphorous speciation and concentration in stormwater in the St. Lucie Estuary watershed, South Florida.

Phosphorous (P) concentration in stormwater runoff varies at different spatial and temporal scales. Excessive P loading from agriculture system into the St. Lucie Estuary (SLE) contributed to water quality deterioration in southern Indian River Lagoon. This study examines the spatial and temporal shifts of different P forms in runoff and storm water under different land use, water management, and rainfall conditions. Storm water samplings were conducted monthly between April 2013 and December 2014 in typical farmland and along the waterway (Canal C-24) that connects lands to the SLE. Concentrations of different P forms and related water quality variables were measured. Approximately 89% of the collected water samples contained total P (TP) concentrations exceeding the total maximum daily load (TMDL) level (0.081 mg L-1). Concentrations of different P forms declined from agricultural field furrows to the canal and then increased from the upstream to the downstream in the canal where urban activities dominated land use. Total dissolved P (TDP) was the predominant form of TP, followed by PO4-P. Speciation and concentrations of P varied with sites and sampling times, but were significantly higher in the summer months (from June to September) than in the winter. Water pH explained ∼20% of TP variation. Spatiotemporal variations of P concentrations and compositions provide a data-based guide for development of best management practices (BMPs) to minimize P export from the SLE watershed.

Heavy metals in composts of China: historical changes, regional variation, and potential impact on soil quality.

Composts are considered one of major sources that contribute heavy metals to the environment. The objective of this study was to investigate historical changes and spatial variation of metal concentrations in Chinese composts by analysing representative compost samples and published data from 2002 to 2013. Mean concentrations of cadmium (Cd), chromium (Cr), lead (Pb), arsenic (As), mercury (Hg), zinc (Zn), nickel (Ni), and copper (Cu) in the composts were 2.42, 35.52, 32.38, 16.33, 0.32, 258.1, 9.71, and 72.24 mg kg-1, respectively. The percentages of samples with metal concentration exceeding critical levels of Chinese standards for organic fertilizers (NY525-2012) were 28.7, 18.3, 9.6, 1.7, and 0.9%, respectively, for Cd, As, Pb, Cr, and Hg. Modelling predicts that it would take 18, 24, 29, and 48 years for Cu, Zn, Hg, and Cd to reach Category I Environmental Capacity of China (GB15618-1995) according to current application rate. During the 2002-2013 period, concentration of Cd in composts tended to decrease with time, whereas those of Zn, Cu, and As were opposite, which is likely due to less or no control for these elements. Concentrations of Cu, Zn, As, and Cd were generally higher in composts from the economically developed regions in China, where more commercial farms were built that use metal-spiked feeds. Manures from the commercial farms generally had higher metal concentration, as compared to the subsistence farms. Further research is needed to monitor metal concentrations from source materials to composts and assess long-term impact of compost application on soil quality.

Spatial and temporal variation of nitrogen concentration and speciation in runoff and storm water in the Indian River watershed, South Florida.

Nitrogen (N) is considered as a key element that triggers algal boom in the Indian River Lagoon (IRL), South Florida. Intensive agriculture may have contributed to increased N input into the IRL. Runoff and storm water samples were collected in representative agricultural fields and along waterways that connect lands to the IRL from April 2013 to December 2014. Concentrations of different N species (particulate N, dissolved organic N, dissolved NH4 (+)-N, and NO3 (-)-N) and related water physical-chemical properties were measured. Total N (TN) concentrations generally decreased from agricultural field furrows to discharging point of the waterways but were generally above the US EPA critical level (0.59 mg L(-1)) for surface water. Organic N was the dominant form of dissolved N, followed by NO3 (-)-N, and dissolved NH4 (+)-N. Concentrations and speciation of N in water varied with sites and sampling times but were generally higher in summer and fall and lower in spring and winter, as affected by the seasonality of regional hydrology and agricultural practices. Correlations occurred between N concentration, water physical properties, and rainfall. This information has important implications in the development of best management practices to minimize the impacts of agricultural practice on N loading in the Indian River Lagoon.

Pyrolysis of wetland biomass waste: Potential for carbon sequestration and water remediation.

Management of biomass waste is crucial to the efficiency and sustainable operation of constructed wetlands. In this study, biochars were prepared using the biomass of 22 plant species from constructed wetlands and characterized by BET-N2 surface area analysis, FTIR, TGA, SEM, EDS, and elemental compositions analysis. Biochar yields ranged from 32.78 to 49.02%, with mesopores dominating the pore structure of most biochars. The biochars had a R50 recalcitrance index of class C and the carbon sequestration potential of 19.4-28%. The aquatic plant biomass from all the Chinese constructed wetlands if made into biochars has the potential to sequester 11.48 Mt carbon yr(-1) in soils over long time periods, which could offset 0.4% of annual CO2 emissions from fossil fuel combustion in China. In terms of adsorption capacity for selected pollutants, biochar derived from Canna indica plant had the greatest adsorption capacity for Cd(2+) (98.55 mg g(-1)) and NH4(+) (7.71 mg g(-1)). Whereas for PO4(3-), Hydrocotyle verticillata derived biochar showed the greatest adsorption capacities (2.91 mg g(-1)). The results from this present study demonstrated that wetland plants are valuable feedstocks for producing biochars with potential application for carbon sequestration and contaminant removal in water remediation.

Uptake and distribution of bisphenol A and nonylphenol in vegetable crops irrigated with reclaimed water.

The potential uptake and distribution of bisphenol A (BPA) and nonylphenol (NP) (from reclaimed irrigation water) in edible crops was investigated. BPA and NP were spiked into simulated reclaimed water at environmentally relevant concentrations. Two crops (lettuce, Lactuca sativa and tomato, Lycopersicon esculentum) were grown hydroponically in a greenhouse using the spiked irrigation water under two irrigation exposure scenarios (overhead foliar exposure and subsurface root exposure). BPA concentrations in tomato fruit were 26.6 ± 5.8 (root exposure) and 18.3 ± 3.5 (foliar exposure) µg kg(-1), while concentrations in lettuce leaves were 80.6 ± 23.1 (root exposure) and 128.9 ± 17.4 (foliar exposure) µg kg(-1). NP concentrations in tomato fruit were 46.1 ± 6.6 (root exposure) and 24.6 ± 6.4 (foliar exposure) µg kg(-1), while concentrations in lettuce leaves were 144.1 ± 9.2 (root exposure) and 195.0 ± 16.9 (foliar exposure) µg kg(-1). BPA was relatively mobile in lettuce plants regardless of exposure route. Limited mobility was observed for NP in both crops and BPA in tomatoes. The estimated daily intake of BPA and NP through consumption of vegetables irrigated with reclaimed water ranged from 8.9-62.9 to 11.9-95.1 µg, respectively, depending on the exposure route.

Phytoavailability of cadmium (Cd) to Pak choi (Brassica chinensis L.) grown in Chinese soils: a model to evaluate the impact of soil Cd pollution on potential dietary toxicity.

Food chain contamination by soil cadmium (Cd) through vegetable consumption poses a threat to human health. Therefore, an understanding is needed on the relationship between the phytoavailability of Cd in soils and its uptake in edible tissues of vegetables. The purpose of this study was to establish soil Cd thresholds of representative Chinese soils based on dietary toxicity to humans and develop a model to evaluate the phytoavailability of Cd to Pak choi (Brassica chinensis L.) based on soil properties. Mehlich-3 extractable Cd thresholds were more suitable for Stagnic Anthrosols, Calcareous, Ustic Cambosols, Typic Haplustalfs, Udic Ferrisols and Periudic Argosols with values of 0.30, 0.25, 0.18, 0.16, 0.15 and 0.03 mg kg-1, respectively, while total Cd is adequate threshold for Mollisols with a value of 0.86 mg kg-1. A stepwise regression model indicated that Cd phytoavailability to Pak choi was significantly influenced by soil pH, organic matter, total Zinc and Cd concentrations in soil. Therefore, since Cd accumulation in Pak choi varied with soil characteristics, they should be considered while assessing the environmental quality of soils to ensure the hygienically safe food production.

Differential iron-bioavailability with relation to nutrient compositions in polished rice among selected Chinese genotypes using Caco-2 cell culture model.

Genotypic variation of iron bioavailability and the relationship between iron bioavailability and nutrient composition in polished rice among 11 rice genotypes were assessed using an in vitro digestion/Caco-2 cell model. The results indicated that significant differences in iron bioavailability were detected among tested rice genotypes, with a 3-fold range, suggesting a possibility of selecting high bioavailable iron by plant breeding. Although iron bioavailability was not significantly correlated with Fe concentration in polished rice among tested rice genotypes, the results also indicated that most of the iron dense genotypes showed relatively high ferritin formation in Caco-2 cell and transported iron. Additionally, iron bioavailability in polished rice was enhanced by addition of ascorbic acid, with a much wider range of Fe bioavailability variation in polished rice with addition of ascorbic acid than that without addition of ascorbic acid. The positive relationship between iron bioavailability in polished rice and cysteine concentration (R = 0.669) or sulfur (S) concentration (R = 0.744) among tested rice genotypes, suggests that cysteine and sulfur concentration in polished rice could be used as an indicator for high iron bioavailability.

Impact of mixed land-use practices on the microbial water quality in a subtropical coastal watershed.

Surface runoff water is an important non-point source of fecal pollution to downstream water; however, there is a lack of systematic studies on the microbial quality of surface runoff water from watersheds with mixed land uses. In this study water samples from 12 surface runoff holding water bodies (SRW), which collected runoff from various patterns of land use within the St. Lucie watershed along the southeastern coastline of Florida, were collected monthly for 22 months. The concentration of fecal indicator bacteria (FIB) and frequency of detection of Salmonella and host specific markers (HF183, CF128, CF193, and HS-esp) were determined, and their associations with land use, rainfall, and water physico-chemical parameters were investigated. Higher FIB concentrations were observed from urban land and cattle ranch sites. Within the same primary land use pattern, different sub-patterns did not have the same level of FIB: golf communities contributed less to fecal pollution than residential areas, and plant nursery sites contained relative higher FIB concentrations than other agricultural sites. Salmonella, CF128, and CF193 markers were more frequently detected from the cattle ranch sites. In contrast the frequency of detecting human specific markers (HF183 and HS-esp) was much higher in residential sites. Rainfall positively affected the concentration of FIB and occurrence of Salmonella, possibly by providing more inputs or mobilizing the sources from sediments. Water temperature, dissolved organic carbon (DOC), and nutrient levels were positively correlated with FIB concentrations and occurrence in SRW, possibly by promoting their growth and survival. This study indicated the need for site specific mitigation strategies to improve SRW and downstream water quality.

Dolomite phosphate rock (DPR) application in acidic sandy soil in reducing leaching of phosphorus and heavy metals-a column leaching study.

A column leaching study was designed to investigate the leaching potential of phosphorus (P) and heavy metals from acidic sandy soils applied with dolomite phosphate rock (DPR) fertilizers containing varying amounts of DPR material and N-Viro soils. DPR fertilizers were made from DPR materials mixing with N-Viro soils at the ratios of 30, 40, 50, 60, and 70 %, and applied in acidic sandy soils at the level of 100 mg available P per kilogram soil. A control and a soluble P chemical fertilizer were also included. The amended soils were incubated at room temperature with 70 % field water holding capacity for 21 days before packed into a soil column and subjected to leaching. Seven leaching events were conducted at days 1, 3, 7, 14, 28, 56, and 70, respectively, and 258.9 mL of deionized water was applied at each leaching events. The leachate was collected for the analyses of pH, electrical conductivity (EC), dissolved organic carbon (DOC), major elements, and heavy metals. DPR fertilizer application resulted in elevations up to 1 unit in pH, 7-10 times in EC, and 20-40 times in K and Ca concentrations, but 3-10 times reduction in P concentration in the leachate as compared with the chemical fertilizer or the control. After seven leaching events, DPR fertilizers with adequate DPR materials significantly reduced cumulative leaching losses of Fe, P, Mn, Cu, and Zn by 20, 55, 3.7, 2.7, and 2.5 times than chemical fertilizer or control. Even though higher cumulative losses of Pb, Co, and Ni were observed after DPR fertilizer application, the loss of Pb, Co, and Ni in leachate was <0.10 mg (in total 1,812 mL leachate). Significant correlations of pH (negative) and DOC (positive) with Cu, Pb, and Zn (P<0.01) in leachate were observed. The results indicated that DPR fertilizers had a great advantage over the soluble chemical fertilizer in reducing P loss from the acidic sandy soil with minimal likelihood of heavy metal risk to the water environment. pH elevation and high dissolved organic carbon concentration in soils after DPR fertilizer application are two influential factors.

Analysis of bisphenol A, nonylphenol, and natural estrogens in vegetables and fruits using gas chromatography-tandem mass spectrometry.

Bisphenol A (BPA), nonylphenol (NP), and steroidal estrogens in vegetables and fruits were analyzed using gas chromatography with tandem mass spectrometry (GC-MS/MS). Isotope dilution standards were spiked before the extraction to account for extraction inefficiency and loss of analytes during sample workup. Recoveries were >90% for all of the compounds in each matrix. The limit of detection (LOD) ranged from 0.03 to 0.3 µg kg(-1), whereas the limit of quantitation (LOQ) ranged from 0.1 to 1.0 µg kg(-1). All analytes can be monitored in a single GC-MS/MS run with a run time of 20 min. Occurrence of these endocrine-disrupting chemicals (EDCs) in vegetables and fruits from local markets was observed using the established analytical method. BPA was detected in all vegetable and fruit samples, ranging from 0.2 ± 0.1 to 9.0 ± 4.9 µg kg(-1), indicating significant exposure potential for humans. NP was detected in pumpkin, sweet potato, citrus, and apple samples. The concentration of 4-n-NP ranged from 5.3 ± 2.4 to 18.9 ± 8.0 µg kg(-1), whereas that of 4-NP ranged from 5.1 ± 2.6 to 12.2 ± 3.6 µg kg(-1). Concentrations of 17-ß-estradiol in vegetables and fruits ranged from 1.3 ± 0.4 to 2.2 ± 1.0 µg kg(-1) except those in tomato and strawberry, in which no 17-ß-estradiol was detected. The estimated daily intake of 17-ß-estradiol was beyond the recommended acceptable daily intake (ADI) for children as recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA).

Isotope dilution-gas chromatography/mass spectrometry method for the analysis of alkylphenols, bisphenol A, and estrogens in food crops.

A gas chromatography/mass spectrometry (GC/MS)-based isotope dilution technique was developed for determination of environmental estrogens in vegetables and fruits. The isotopically labeled standards of related environmental estrogens were used as the isotope dilution standards (IDS) to form the following analyte/surrogate pairings: octylphenol/(13)C6-4-n-nonylphenol, 4-n-nonylphenol/(13)C6-4-n-nonylphenol, 4-nonylphenol/(13)C6-4-n-nonylphenol, bisphenol A/(13)C12-bisphenol A, estrone/(13)C6-estrone, 17-α-estradiol/(13)C6-ß-estradiol, 17-ß-estradiol/(13)C6-ß-estradiol, 17-α-ethynylestradiol/(13)C2-17-α-ethynylestradiol, and estriol/D4-estriol. Plant samples were homogenized and extracted ultrasonically with acetone. Acid pretreatment greatly increased peak intensities for the analytes. Acid hydrolysis pretreatment was important for liberating conjugates of estrogenic contaminants in plant materials. Recoveries of the spiked analytes were greater than 90%. Method limits of detection (LOD) ranged from 0.01 to 0.20 µg kg(-1) while limits of quantification (LOQ) ranged from 0.04 to 0.60 µg kg(-1). Bisphenol, nonylphenol, and natural estrogens were detected in vegetable and fruit samples obtained from local markets, illustrating the feasibility of this method for determining trace estrogenic contaminants in vegetables and fruits. The method has significant environmental implications in terms of the simultaneous analysis of estrogenic contaminants in vegetables and fruit.