Effect of exogenous Ca on the physiology and growth indicators of pakchoi under foliar and root fluorine stress.

Fluorine (F) is not an essential element for vegetation and excessive F can be phytotoxic to plant growth, which can cause fluorosis to human beings by ingesting F-contaminated plant. Although there have been some studies focusing on the toxicity of F to plants and the retarding effect of Ca to F-stress plant, atmospheric F contamination to vegetation and the role of the application of foliar Ca are scantly reported. This study investigated several biochemical parameters to evaluate F toxicity under both F-exposure (root and leaf F-exposure) and the remedial effects of foliar Ca. The results showed that F concentration of pakchoi leaves was correlated with exogenous F level positively in both foliar and root F-exposure series, and F concentration of pakchoi roots was only changed under root F-exposure treatments. Ca supplement (0.5 g/L and 1 g/L) significantly decreased plant F concentration. Both F-exposure treatments caused lipid peroxidation in plants and exogenous Ca alleviated the toxicity of F to pakchoi. Meanwhile, chlorophyll-a concentration was decreased by foliar and root F, whereas chlorophyll-b concentration was only affected by foliar F, and chlorophyll-a concentration could be elevated by exogenous Ca but chlorophyll-b could not. It was concluded that both atmospheric and root F can impair pakchoi growth and disturb photosynthesis, and foliar Ca showed an ameliorative effect to F toxicity of pakchoi through alleviating chlorophyll decomposition, increasing protein content and alleviating oxidative damage.

Health risk of fluorine in soil from a phosphorus industrial area based on the in-vitro oral, inhalation, and dermal bioaccessibility.

Health risk of F in soil is of special concern due to the continuously elevated concentration of F in soil. However, there is still a dearth of risk assessments of F in soil based on in-vitro bioaccessibility posed by multiple exposure routes. Herein, the oral, inhalation, and dermal bioaccessibility of F in soil was firstly obtained by adapting and combining in-vitro methods, which then was introduced to remedy an information gap of a comprehensive risk of F in soil posed by a multi-exposure pathway. Combined in-vitro tests indicate the oral, inhalation, and dermal bioaccessibility of F was 13.15 ± 2.63%, 16.55 ± 2.63%, and 1.27 ± 0.73%, respectively. Plasma yielded a detoxic potential for the absorbed F after digesting in small intestine, while effects of enzymes, sweat, and food on the oral bioaccessibility of F were insignificant. Different with metals, the major dissolving phase of F was the interstitial fluid in the deep lung instead of in the alveolar macrophages intracellular environment. A potentially major release of F in the exocrine sweat was noted than in the apocrine sweat. Risk assessments based on the daily exposure incorporated with the in-vitro bioaccessibility suggested that compared with inhalation and dermal contact, oral ingestion was the main exposure route of F in soil to human. Present findings provide insights into the bioaccessibility and health risk of F in soil by multiple exposure routes, which are crucial for the risk control of F contamination in soil.

Transfer characteristic of fluorine from atmospheric dry deposition, fertilizers, pesticides, and phosphogypsum into soil.

Fluorine (F) is widely dispersed in the environment and frequently used in industry and agriculture with a high migration ability. Thus, it is essential to understand the leaching characteristic of F in soil from industry and agriculture sources. Several sources of F pollutants in soil, including fertilizers, pesticides, phosphogypsum, and atmospheric deposition, were selected to investigate leaching characteristics of F in soil by leaching experiments. The addition of phosphate fertilizer and compound fertilizer (N:P:K = 20:10:15) enhanced the leachability of F in soil and the proportion of F leached out from soil treated by these fertilizers were 0.25% and 0.24%, respectively. However, unanticipated lower leachability of F appeared in compound fertilizer (N:P:K = 17:17:17), nitrogen fertilizer, dipterex, fluoroglycofen, fluopimomide, simulative dry deposition (YF3), and phosphogypsum loaded soils compared with additive-absent treatment. Although phosphogysum had a high F concentration, minimum proportion of F released (0.18%) was observed in phosphogypsum-coverd soil. The amounts of F leaching-out from surface soils (0-25 cm) treated with nitrogen fertilizer decreased 1.03 kg ha-1 comparing with blank control. Soil with phosphate fertilizer leached 5.47 kg F ha-1 a year, having the highest environment risk to deeper soil and groundwater. However, phosphogypsum and dry deposition of airbone F chemical had few effects on F leaching in soil. F-containing materials from agricultural process may leach more F from surface soils than industrial sources.

Remediation of fluoride contaminated soil with nano-hydroxyapatite amendment: Response of soil fluoride bioavailability and microbial communities.

Nano-hydroxyapatite (NHAP), possessing high defluoridation capacity, has been widely used to remove fluoride (F) from polluted water, but little is known about how it affects the bioavailability and toxicity of soil F towards plants. Here, the impact of NHAP (2% w/w) amendment on immobilization, speciation and accumulation of F was studied in a soil-plant system. The results revealed that the NHAP amendment worked effectively to reduce levels of water-soluble F (37.3%-87.8%) and increase available P (76.6%-147%). X-ray photoelectron spectroscopy analysis indicated that the formation of insoluble CaF2 and the ion exchange of F- with OH- into NHAP might be involved in the mechanism of F immobilization and soil pH elevation. Exposure to NHAP significantly decreased the abundance of Cyanobacteria in tested soils, and Gemmatimonadetes abundance in bulk soil was significantly higher than that in rhizosphere soil at 1,000 mg kg-1 F spiked level. Additionally, NHAP amendment decreased F accumulation in wheat shoots (9.10%-18.7%) and roots (3.88%-22.4%), which could mainly be attributed to the reduction of soil bioavailable F and the supplement of Ca from NHAP. These results suggest that NHAP could be a promising amendment to be applied to acidic soil contaminated with F.

Distribution and superposed health risk assessment of fluorine co-effect in phosphorous chemical industrial and agricultural sources.

The industrial and agricultural activities based on phosphorous can increase the F content in the surrounding area, causing a widespread adverse effect on the organisms. However, the current information on the superposed health risk posed by the multi-exposure to the F contamination in an area jointly affected by agricultural and industrial activities (DA) is limited. Herein, the F distribution in multi-environmental media and the exposure risk to humans by ingestion, inhalation, and dermal contact pathways are studied in an DA. The content of soil water-soluble fluorine (WF) was higher in the DA than in the area individually affected by agricultural activities (SA). This indicated a superposed contribution of the industrial and agricultural activities to increase the F toxicity in the soil. The correlation of the soil pH and the organic matter content with the soil WF concentration in DA suggested an inter-relationship between the soil physicochemical properties and the toxicity of F in the soil by industrial and agricultural activities. Irrigation water was not a major anthropogenic source of the cropland soil F. The large variation in F concentration in the crops (101.8-195.6%) might have originated from the discrepancies in the soil F content and air F concentration. The air F pollution (0.6-1.6 µg dm-2 d-1) in the area particularly influenced by intensive industrial activities should be important. The exposure of residents to F was mainly from the ingestion of F-enriched crops. The higher exposure of adults to F than that of children could be attributed to more industrial and agricultural outdoor activities, larger exposure area of the skin, and more daily ingestion of F-enriched food by adults. Overall, present insights into the distribution of and the multi-exposure to F may be beneficial for decreasing the adverse F effects on the residents in DAs worldwide.

Distribution, health risk assessment, and anthropogenic sources of fluoride in farmland soils in phosphate industrial area, southwest China.

The high concentration of fluoride (F) in soils has become a rising concern for its toxicity to microbes, plants, animals and human health. In the present study, the spatial and vertical distribution, health risk assessment and anthropogenic sources of F in farmland soils in an industrial area dominated by phosphate chemical plants were studied. Concentrations of total fluoride (TF) and water soluble fluoride (WSF) in the surface soils decreased with distance within the range of 2500 m at the prevailing downwind of the industrial area. The soil TF and WSF concentrations in 0-40 cm profiles were higher than those in 40-100 cm layers in the industrial area. At the prevailing downwind of the industrial area within 700 m, the hazard quotient values of human exposure to surface soils were higher than 1, indicating that a potential risk may exist for human health in this area. The main exposure pathway for children and adults was oral ingestion and particulate inhalation, respectively. The source apportionment model of soil F was modified based on years' historical data and experimental data. The results showed that the proportion of anthropogenic sources of soil F was dustfalls (69%) > irrigation water (23%) > air (5%) > chemical fertilizers (3%) in the industrial area. The high F concentration of dustfalls was mainly due to the phosphate rock, phosphogypsum, and surface soils with high F contents from the factories. In order to safeguard human health and alleviate hazards of F to surroundings, the control of pollutants emission from factories was a basic and vital step to reduce F in the soils in industrial areas.

Relationship between rosacea and dietary factors: A multicenter retrospective case-control survey.

Although patients with rosacea often consult dermatologists for dietary factors that might be related to their skin disorders, few studies have been conducted to research the relationship between rosacea and dietary factors. The purpose of this study was to evaluate the potential relationship between rosacea and diet among the large Chinese population with rosacea, which would provide dietary guidelines for patients with rosacea. A multicenter case-control study was conducted. The feeding frequency 2 years before the occurrence of rosacea was collected by standardized questionnaires. Multiple logistic regression analysis was used to calculate risks related to the diet. One thousand three hundred and forty-seven patients with rosacea and 1290 controls were enrolled in our study. We found that high-frequency intake of fatty food and tea presented a positive correlation with rosacea, while high-frequency dairy product intake showed significant negative correlation with rosacea. Sweet food, coffee and spicy food appeared to be independent of any subset of rosacea in our study. However, high-frequency dairy product intake showed a borderline beneficial effect on rosacea severity. We further analyzed the correlation between diet and the subtype of rosacea. We found that high-frequency fatty intake was associated with erythematotelangiectatic rosacea (ETR) and phymatous rosacea, while high-frequency tea intake was only associated with ETR. In addition, high-frequency dairy product intake showed negative correlations with ETR and papulopustular rosacea. Rosacea is associated with some dietary factors, and our study is valuable in establishing dietary guidelines to prevent and improve rosacea.

Vertical distribution of fluorine in farmland soil profiles around phosphorous chemical industry factories.

High concentration of fluorine (F) in agricultural soils has got significant attention considering its impacts on human health, but little information was available about F distribution in farmland soil profiles around phosphorous chemical industry factories. In present study, farmland soil profiles and relevant medium samples were collected from farmlands around a main phosphorous chemical base in southwest China. At 0-100-cm profiles, concentrations of soil total F (Ft, 400.9-1612.0 mg kg-1) and water soluble F (Fw, 3.4-26.0 mg kg-1) decreased with profile depth in industrial areas. Industrial activities enhanced F concentration in soil mainly at 0-40-cm profiles. No disparity for both Ft and Fw distributions in paddy-dry land rotation field and dry land indicates short-term land utilization could not affect the F distribution in soil profiles. Correlation analysis showed soil organic matter and wind direction were important factors influencing the distribution of F in soil profiles. The shutdown of factory and government control of industrial emissions effectively decreased the ambient air F (Fa) concentrations in industrial areas. In where Fa and dustfall F concentrations were high, high soil Ft, Fw, and crop edible part F concentrations were found.

Effect of lead on plant availability of phosphorus and potassium in a vegetable-soil system.

Two typical red soils were sequentially cultivated with celery (Apium graveolens L.) and Chinese cabbage (Brassica chinensis L.) in a greenhouse to determine the effect of lead (Pb) on plant availability of phosphorus (P) and potassium (K) in the soils. The concentrations of available P as estimated by the 0.05 mol L-1 HCl-0.025 mol L-1 (1/2 H2SO4) extraction and available K estimated by the NH4OAc extraction method in the crop-free soils were not affected by Pb treatment. Plant P concentrations in the above-ground part of celery and Chinese cabbage exposed to Pb were either lower or showed no significant difference to the control.

Damage suffered by swamp morning glory (Ipomoea aquatica Forsk) exposed to vanadium (V).

To elucidate the physiological and morphological responses generated by vanadium (V) in plants, hydroponic culture experiments were performed with swamp morning glory (Ipomoea aquatica Forsk) exposed to 0 mg L(-1) to 2.50 mg L(-1) pentavalent V [V(V)] in Hoagland nutrient solutions. The concentration of chlorophyll a, chlorophyll b, and carotene peaked at a V(V) concentration of 0.05 mg L(-1) and gradually decreased at higher V(V) concentrations. Similarly, the plant biomass was stimulated at low levels of V(V) and was inhibited when V(V) concentrations exceeded 0.1 mg L(-1). Pentavalent V had negative effects on the uptake of phosphorus (P) by roots, shoots, and leaves. The biological absorption coefficients of V of the roots were higher than those of the aerial parts. Under low concentrations of V(V) exposure, the predominant species of V in the aerial parts was tetravalent V [V(IV)], whereas V(V) became more prevalent when concentrations of V(V) in the solution was higher than 0.50 mg L(-1). In the roots, however, the concentrations of V(V) were always higher than those of the V(IV), except in the control group. Organelles in the V(V)-treated leaves were distorted, and the periplasmic space became wider. These results indicate V(V) has concentration-dependent effects on the physiological properties of swamp morning glory, whereas the plant has the ability to develop self-protective function to adapt to the toxicity of V(V).

[In Situ High-Resolution Analysis of Labile Phosphorus in Sediments of Lake Chaohu].

High-resolution pore water equilibrators (HR-Peeper) and diffusive gradients in the thin films ( DGT) technologies were combined to in situ measure soluble reactive phosphorus (c(PW)) and labile phosphorus (C(DGT)) on seven sites in the west of Lake Chaohu. Vertical distributions of c(PW) and c(DGT) in most sediment profiles were similar to a different extent, demonstrating that the buffer capacity of the sediment solids to pore water SRP was similar at different depths. The diffusion flux across the sediment-water interface (SWI) and the ratio of cDGT/ c(PW) (R) were used to characterize phosphorus activity in sediments. From the center of the lake to the estuary of Nanfei River, the values of c(PW) and c(DGT) within the 6 mm layer were below the SWI and the SWI diffusion flux gradually increased, reflecting an increase in pollution level of sediment phosphorus. The change of R values was unconspicuous, indicating that the buffering capacity of the interface sediment had no significant difference.

Uptake and speciation of vanadium in the rhizosphere soils of rape (Brassica juncea L.).

The response of rape (Brassica juncea L.) to different vanadium (V) speciation in rhizosphere soils was investigated in pot experiments using an agricultural soil containing 147 mg V kg(-1) supplemented with 0-500 mg V kg(-1) of pentavalent V [V(V)] and a mining soil containing 774 mg V kg(-1). Tetravalent V [V(IV)] accounted for 76.1 and 85.9 % of total V in the untreated agricultural soil and mining soil, respectively. The proportion of both V(V) and water-extractable V increased with increasing concentrations of V(V) in the agricultural soil. The growth of rape substantially reduced the concentrations of V(V) but not V(IV) in the rhizosphere soil, suggesting that V(V) was actively involved in the soil-rape interaction of V. Both soil V(V) and water-extractable V were negatively related to the total rape biomass, but were positively correlated with the concentration of root V. No such relationships were found for total V and soil V(IV). Together, these results indicate that soil V(V) and water-extractable V might better reflect the toxicity of V in soils than total V and soil V(IV). Rape accumulated V in the sequence: roots > > stem > leaf > seed. As indicated by the remarkably low root bioconcentration factor of V(V) (0.41-7.24 %), rape had a lower ability to accumulate V than other plants reported in the literature (14.6-298 %). Only a small fraction of V in rape roots was translocated to the aboveground organs (the translocation factor was 3.57-46.9 %). No V was detectable in seeds in the soils at 147 and 197 mg V kg(-1), and no seed was produced in the soils at higher V concentrations. Thus, the risk of V intake by humans via the consumption of rapeseed-based foods under normal conditions is considered to be lower than that of other plants.

New triterpene saponins from the root of Ilex pubescens.

Two new triterpene glycosides named ilexpublesnin A (1) and ilexpublesnin B (2) were isolated from the root of Ilex pubescens. Their structures were determined as 3-O-(ß-D-xylopyranosyl)-28-O-(ß-D-glucopyranosyl)-3ß, 19α-dihydroxyurs-23-oxo-12-en-28-oic acid (1) and 28-O-(ß-D-xylopyranosyl-(2→1)-ß-D-glucopyranosyl)-3ß, 19α-dihydroxyurs-23-oxo-12-en-28-oic acid (2) on the basis of chemical and spectroscopic methods.