[Research on mechanism of hypolipidemic effect of Massa Medicata Fermentata based on metabolomics].

This paper aims to study the therapeutic effect of Massa Medicata Fermentata on hyperlipidemia model rats and investigate its mechanism of hypolipidemic effect with the help of non-targeted metabolomics. The mixed hyperlipidemia model rats were constructed by giving high-fat chow. After successful modeling, the rats were divided into the model group, pravastatin sodium group(4.4 mg·kg~(-1)), lipotropic group(0.1 g·kg~(-1)), high-dose group(2.4 g·kg~(-1)), medium-dose group(1.2 g·kg~(-1)), and low-dose group(0.6 g·kg~(-1)) of Massa Medicata Fermentata, and they were administered for four weeks once daily. An equal volume of ultrapure water was given to the blank group and model group. Serum lipid level and liver hematoxylin-eosin(HE) staining were used as indicators to estimate the intervention effect of Massa Medicata Fermentata on mixed hyperlipidemia, and the changes in metabolites in plasma of mixed hyperlipidemia model rats were analyzed by non-targeted metabolomics. The mechanism of the hypolipidemic effect of Massa Medicata Fermentata was analyzed through metabolite pathway enrichment. The results showed that compared with the model group, the Massa Medicata Fermentata administration group, especially the high-dose group, could significantly reduce the content of total cholesterol(TC), triglyceride(TG), and low-density lipoprotein cholesterol(LDL-c)(P<0.05 or P<0.01), and liver HE staining revealed that the number of adipocytes in the high-dose group was reduced to some extent. The potential biomarkers obtained by non-targeted metabolomics screening included glycerol 3-phosphate, sphingomyelin, sphingosine 1-phosphate, and deoxyuridine, which were mainly involved in the sphingolipid metabolism process, glycerophospholipid metabolism process, glycerol ester metabolism pathway, and pyrimidine metabolism pathway, totaling four possible metabolic pathways related to lipid metabolism. This study provides a reference for an in-depth investigation of the hypolipidemic mechanism of Massa Medicata Fermentata, which is of great significance for further promoting the clinical application of Massa Medicata Fermentata and increasing the indications.

Screening of Potential α-Glucosidase Inhibitors from the Roots and Rhizomes of Panax Ginseng by Affinity Ultrafiltration Screening Coupled with UPLC-ESI-Orbitrap-MS Method.

Panax ginseng was a traditional Chinese medicine with various pharmacological activities and one of its important activities was hypoglycemic activity; therefore, panax ginseng has been used in China as an adjuvant in the treatment of diabetes mellitus. In vivo and in vitro tests have revealed that ginsenosides, which are derived from the roots and rhizomes of panax ginseng have anti-diabetic effects and produce different hypoglycemic mechanisms by acting on some specific molecular targets, such as SGLT1, GLP-1, GLUTs, AMPK, and FOXO1. α-Glucosidase is another important hypoglycemic molecular target, and its inhibitors can inhibit the activity of α-Glucosidase so as to delay the absorption of dietary carbohydrates and finally reduce postprandial blood sugar. However, whether ginsenosides have the hypoglycemic mechanism of inhibiting α-Glucosidase activity, and which ginsenosides exactly attribute to the inhibitory effect as well as the inhibition degree are not clear, which needs to be addressed and systematically studied. To solve this problem, affinity ultrafiltration screening coupled with UPLC-ESI-Orbitrap-MS technology was used to systematically select α-Glucosidase inhibitors from panax ginseng. The ligands were selected through our established effective data process workflow based on systematically analyzing all compounds in the sample and control specimens. As a result, a total of 24 α-Glucosidase inhibitors were selected from panax ginseng, and it was the first time that ginsenosides were systematically studied for the inhibition of α-Glucosidase. Meanwhile, our study revealed that inhibiting α-Glucosidase activity probably was another important mechanism for ginsenosides treating diabetes mellitus. In addition, our established data process workflow can be used to select the active ligands from other natural products using affinity ultrafiltration screening.

Comprehensive Identification of Ginsenosides in the Roots and Rhizomes of Panax ginseng Based on Their Molecular Features-Oriented Precursor Ions Selection and Targeted MS/MS Analysis.

Panax ginseng is widely used in Asian countries and its active constituents-ginsenosides-need to be systematically studied. However, only a small part of ginsenosides have been characterized in the roots and rhizomes of panax ginseng (RRPG) up to date, mainly because of a lack of the fragmentation ions of many more ginsenosides. In order to comprehensively identify ginsenosides in RRPG, molecular features of ginsenosides orienting precursor ions selection and targeted tandem mass spectrometry (MS/MS) analysis strategy were proposed in our study, in which the precursor ions were selected according to the molecular features of ginsenosides irrespective of their peak abundances, and targeted MS/MS analysis was then performed to obtain their fragmentation ions for substance characterization. Using this strategy, a total of 620 ginsenosides were successfully characterized in RRPG, including 309 protopanaxadiol-type ginsenosides, 258 protopanaxatriol-type ginsenosides and 53 oleanane-type ginsenosides. It is worth noting that, except for the known aglycones mass-to-charge ratio (m/z) 459, 475 and 455, twelve other aglycones, including m/z 509, 507, 493, 491, 489, 487, 477, 473, 461, 457, 443 and 441, were first reported in our experiment and they were probably the derivatizations of the protopanaxatriol and protopanaxadiol. Our study will not only help people to improve the cognition of ginsenosides in RRPG, but will also play a guiding and reference role for the isolation and characterization of potentially new ginsenosides from RRPG.

Xin-Ji-Er-Kang Alleviates Isoproterenol-Induced Myocardial Hypertrophy in Mice through the Nrf2/HO-1 Signaling Pathway.

Xin-Ji-Er-Kang (XJEK) inhibited cardiovascular remodeling in hypertensive mice in our previous studies. We hypothesized that XJEK may prevent isoproterenol (ISO)-induced myocardial hypertrophy (MH) in mice by ameliorating oxidative stress (OS) through a mechanism that may be related to the nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1(HO-1) pathways. Forty SPF male Kunming mice were randomized into 5 groups (n = 8 mice per group): control group, MH group, MH + different doses of XJEK (7.5 g/kg/day and 10 g/kg/day), and MH + metoprolol (60 mg/kg/day). On the eighth day after drug treatment, electrocardiogram (ECG) and echocardiography were performed, the mice were sacrificed, and blood and heart tissues were collected for further analysis. XJEK administration markedly ameliorated cardiovascular remodeling (CR), as manifested by a decreased HW/BW ratio and CSA and less collagen deposition after MH. XJEK administration also improved MH, as evidenced by decreased atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), and ß-myosin heavy chain (ß-MHC) levels. XJEK also suppressed the decreased superoxide dismutase (SOD) and catalase (CAT) activities and increased malondialdehyde (MDA) levels in serum of mice with MH. XJEK-induced oxidative stress may be related to potentiating Nrf2 nuclear translocation and HO-1 expression compared with the MH groups. XJEK ameliorates MH by activating the Nrf2/HO-1 signaling pathway, suggesting that XJEK is a potential treatment for MH.

Quality and yield of Pseudostellaria heterophylla treated with GGBS as pH adjuster against the toxicity of Cd and Cu.

The contamination of Cd and Cu in soil is a great threat to medicinal plant. Ground granulated blast furnace slag (GGBS) is a potential soil pH adjuster to reduce metal toxicity. However, how GGBS affects the quality and yield of herbal plants under the stress of Cd and Cu is not clear. This study aims to investigate the quality and yield of a medicinal plant (Pseudostellaria heterophylla) responding to GGBS treatment in Cd and Cu contaminated soil. GGBS with three mass percentages (0%, 3%, 5%) was added into contaminated lateritic soils for planting. Each condition had 21 replicated seedlings. The concentrations of Cd and Cu in plant, amounts of active ingredients (polysaccarides and saponins) in medicinal organ, and tuber properties were measured after harvest. The results showed that under 3% and 5% GGBS treatments, Cd and Cu accumulations in all plant organs (leaf, stem, root and tuber) were reduced by 69.4-86.0% and 10.3-30.1%, respectively. They were below the permissible limits (World Health Organization, WHO). Even though the concentrations of active ingredients in P. heterophylla tuber decreased by up to 35.8%, they still met Hong Kong Chinese Materia Medica standard. Besides, the biomass of root tuber increased by 9.8% and 46%, due to 3% and 5% GGBS treatments, respectively. The recommended 5% GGBS treatment in practice can balance the reduction of active ingredients and the increase of plant yield when minimizing Cd and Cu accumulation in tuber.

[Profiling and identification of in vivo metabolism of rosmarinic acid in rats].

Rosmarinic acid,a hydrosoluble polyphenolic hydroxyl compound,is the active ingredient in such traditional Chinese medicines as Menthae Haplocalycis Herba,Salviae Miltiorrhizae Radix et Rhizoma,Rosemary,Perillae Folium. Because of its good anti-inflammatory,anti-oxidant and anti-tumor effects,it is widely used in food,medicine and other fields. However,the metabolic process and metabolites of rosmarinic acid in vivo have not been completely defined. In this study,an efficient method of ultra-high performance liquid chromatography combined with linear ion trap-Orbitrap(UHPLC-LTQ-Orbitrap) mass spectrometer was used to analyze the metabolites in vivo of rosmarinic acid in rats. Plasma,urine and feces samples were collected after oral administration of rosmarinic acid. After biological samples were processed by solid phase extraction,Acquity UPLC  BEH C18 column(2. 1 mm × 100 mm,1. 7 µm) was used with 0. 1% formic acid(A)-acetonitrile(B) solution as the mobile phase at the speed of 0. 30 m L·min-1 and temperature of 35 ℃ under gradient conditions. The plasma,urine,feces and the blank samples were then analyzed by ESI-LTQ-Orbitrap under both negative and positive ion modes. Based on the accurate mass measurement(<5),MS/MS fragmentation patterns,standards and literatures,a total of 36 metabolites were screened out and identified in the biological samples collected from rats after intragastric administration. Three were identified 3 from rat plasma,31 from urine,and 7 from feces. The main metabolic pathways of rosmarinic acid in rats can be divided into five parts. Rosmarinic acid were first decomposed into small molecules,such as trans-caffeic acid,coumaric acid,m-hydroxybenzoic acid and Danshensu,which were followed by sulfation,methylation,glucuronic acid conjugation and glucose conjugation. The results showed that UHPLC-LTQ-Orbitrap mass spectrometer could be used to analyze the metabolism of rosmarinic acid in rats,and provide reference for further studies on toxicology,pharmacodynamics and secondary development of Chinese medicine.

Estradiol Treatment during Perinatal Development Alters Adult Partner Preference, Mating Behavior and Estrogen Receptors α and ß in the Female Mandarin Vole (Microtus mandarinus).

During development, many aspects of behavior, including partner preferences and sexual conduct, are "organized" by estradiol. This study aimed at analyze these processes in the mandarin vole (Microtus mandarinus), a novel experimental mammal with strong monogamous pair bonds. Female pups were treated daily with an oil vehicle (FC) or ß-Estradiol (E2, FT) from prenatal day 14 to postnatal day 10. Male pups were treated daily with the oil vehicle only (MC). Partner preferences, sexual conduct and the expression of estrogen receptors α (ERα) and ß (ERß) were examined when animals were 3 months old. FT and MC groups showed female-directed partner preferences and masculinized behavior. ERα- immunoreactive neurons (ERα-IRs) in the bed nucleus of stria terminalis (BNST) and medial amygdaloid nucleus (MeA) was greater in FT females than MC males, and there was no significant difference in the number of ERα-IRs between FT and FC females. No difference was found for ERα-IRs in the preoptic area (mPOA) or ventromedial nucleus of the hypothalamus (VMH) of FT females or MC males, and they were significantly fewer than in FC females. ERß-immunoreactive neurons (ERß-IRs) in these four brain regions did not alter the ERß/ERα ratio in different brain regions during perintal developments. However, the number of ERß-IRs in FT females and MC males were greater than in FC females. We propose that estradiol treatment during perinatal development is responsible for adult partner preferences and mating behavior.

[Identification of metabolites of Danshensu in vivo in rats].

To identify the metabolites of Danshensu in plasma and urine in rats by using UHPLC-LTQ-Orbitrap method. After oral gavage of Danshensu CMC-Na suspension in SD rats, urine and plasma samples were collected and processed by solid phase extraction. ACQUITY UPLC BEH C18 column (2.1 mm×100 mm, 1.7 µm) was utilized, with 0.1% formic acid (A)-acetonitrile (B) solution as the mobile phase for gradient elution. Negative electrospray ion mode based data-acquisition method was established to collect the mass spectrometry data of biological samples. As a result, Danshensu and 21 Danshensu Ⅰ phase and Ⅱ phase metabolites were finally identified according to the accurate mass measurements, mass fragmentation behaviors and comparing with the reference standards. The main metabolic pathways included dehydration, methylation, glucuronide conjugation, sulfate conjugation and their composite reactions. Consequently, our study expounded metabolites of Danshensu in rats based on UHPLC-LTQ-Orbitrap method and provided a reference for further researches on therapeutic material basis and mechanism of Danshensu.

[Metabolites of tanshinone â and tanshinone â ¡A in vivo in rats].

An efficient method of ultra-high performance liquid chromatography coupled with linear ion trap-Orbitrap (UHPLC-LTQ-Orbitrap) mass spectrometer was established to elucidate the in vivo metabolites of tanshinone Ⅰ and tanshinone ⅡA in rats. Urine and plasma samples were collected after oral gavage. After processing biological sample by solid phase extraction, Waters ACQUITY HPLC BEH C18 column (2.1 mm×100 mm, 1.7 µm) was used with 0.1% formic acid (A) - acetonitrile (B) solution as the mobile phase for gradient elution. The plasma, urine and the blank samples were then analyzed by ESI-LTQ-Orbitrap equipped with an ESI ion source under positive ion mode. On the basis of the accurate mass measurements, multiple mass spectra and comparison of data with published literature, a total of 26 metabolites were tentatively identified and characterized in the rat samples. Among them, 7 metabolites were derived from tanshinone Ⅰ through metabolic pathways of glucuronide conjugation, hydroxylation, reduction reaction, demethylation reaction, methylation, sulfate conjugation and their composite reactions. Nineteen metabolites were derived from tanshinone ⅡA through metabolic pathways of hydroxylation, reduction reaction, methylation, sulfate conjugation, glucuronidation, glucosylation and their complicated reactions. The results showed that the metabolism of tanshinone Ⅰ and tanshinone ⅡA in rats could be comprehensively clarified by using UHPLC-LTQ-Orbitrap mass spectrometer, providing material basis for the further research in terms of pharmacodynamics, toxicology, and secondary development of Chinese medicine.

Rapid Characterization and Identification of Non-Diterpenoid Constituents in Tinospora sinensis by HPLC-LTQ-Orbitrap MSn.

Tinospora sinensis, a kind of Chinese folk medicine, has functions of harmonizing qi and blood, dredging the channels and collaterals, calming and soothing the nerves. In the present study, a method based on high-performance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry (HPLC-LTQ-Orbitrap) was developed for the systematical characterization of the non-diterpenoid constituents which possessed remarkable biological activities in T. sinensis, like anti-tumor, anti-inflammatory, hypoglycemic activity and immunomodulatory activity. Based on the accurate mass measurement (<5 ppm), retention times and MS fragmentation ions, 60 non-diterpenoid constituents were unambiguously or tentatively characterized from T. sinensis extract, including 27 alkaloids, 23 phenylpropanoids, seven sesquiterpenoids and three other constituents. Among them, 13 compounds were tentatively identified as new compounds. Finally, three of the non-diterpenoid constituents were purified and identified, which further confirmed the validity of the results. This study demonstrated that the HPLC-LTQ-Orbitrap MSn platform was a useful and efficient analytical tool to screen and identify constituents in natural medicine.

Rapid Screening and Identification of Diterpenoids in Tinospora sinensis Based on High-Performance Liquid Chromatography Coupled with Linear Ion Trap-Orbitrap Mass Spectrometry.

Diterpenoids are considered the major active compounds in Tinospora sinensis in virtue of their special structures and activities. Herein, an analytical method was developed for rapid screening and identification of diterpenoids in T. sinensis using high-performmance liquid chromatography coupled with linear ion trap-Orbitrap mass spectrometry (HPLC-LTQ-Orbitrap) in negative ion mode. Two diterpenoid reference standards were first analyzed to obtain their characteristic ESI-MS/MS fragmentation patterns. Then, based on the extracted ion chromatogram (EIC) data-mining method and characteristic fragmentation pathways analysis, diterpenoids in T. sinensis were rapidly screened and identified. After that, an important parameter, Clog P, was adopted to discriminate between the isomers of diterpenoids. As a result, 63 diterpenoids were characterized from the extract of T. sinensis, including 10 diterpenoids and 53 diterpenoid glycosides. Among them, 15 compounds were tentatively identified as new compounds. Finally, target isolation of one diterpenoid glycoside named tinosineside A was performed based on the obtained results, which further confirmed the deduced fragmentation patterns and identified diterpenoid profile in T. sinensis. The results demonstrated that the established method could be a rapid, effective analytical tool for screening and characterization of diterpenoids in the complex systems of natural medicines.

The genus Liriope: Phytochemistry and pharmacology.

Liriope (Liliaceae) species have been used as folk medicines in Asian countries since ancient times. From Liriope plants (8 species), a total of 132 compounds (except polysaccharides) have been isolated and identified, including steroidal saponins, flavonoids, phenols, and eudesmane sesquiterpenoids. The crude extracts or monomeric compounds from this genus have been shown to exhibit anti-tumor, anti-diabetic, anti-inflammatory, and neuroprotective activities. The present review summarizes the results on phytochemical and biological studies on Liriope plants. The chemotaxonomy of this genus is also discussed.

UHPLC-LTQ-Orbitrap-based metabolomics coupled with metabolomics pathway analysis method for exploring the protection mechanism of Kudiezi injection in a rat anti-ischemic cerebral reperfusion damage model.

Kudiezi injection has been used extensively in the treatment of cerebrovascular and cardiovascular diseases. However, its therapeutic effects and underlying mechanism of action are not fully understood. The aim of the present study was to clarify the protective mechanisms of Kudiezi injection on cerebral ischemic injury, using metabolomics methods. Middle cerebral artery occlusion (MCAO) was introduced in rats to build the cerebral ischemic damage. UHPLC-LTQ-Orbitrap-based analytical method was established for analysis of the metabolites. The raw mass data of all samples were normalized with Sieve 2.2 software and then introduced to orthogonal partial least squares discriminant analysis (OPLS-DA) model. Finally, 23 metabolites in plasma (15 were tentatively identified) were chosen as potential biomarkers, according to accurate mass measurements (< 5 ppm), MS/MS fragmentation patterns, and diagnostic product ions. Furthermore, on the basis of metabolic pathway analysis via metabolomics pathway analysis (MetPA), we first discovered that the protection mechanism in anti-ischemic cerebral reperfusion damage of Kudiezi injection was possibly related to the biosynthesis of phenylalanine, tyrosine, and tryptophan. The present study provided a useful approach for exploring the mechanism of ischemic stroke and evaluating the efficacy of Kudiezi injection or other traditional medicines.

[Influence of different drying methods on steroidal saponins and homoisoflavonoids in Ophiopogon japonicus].

To study the influence of three different drying methods (including 50 ℃-drying, 80 ℃-drying and －70 ℃-freeze-drying methods) on steroidal saponins and homoisoflavonoids in Ophiopogon japonicus,a HPLC-DAD-ELSD-MSn method was investigated to screen and identify the differential components. Through comparing the HPLC chromatograms with that of fresh O. japonicus, 50 ℃-drying medicine was similar with fresh medicine whereas the other two drying methods had great influence on the components of O. japonicus. In this study, 36 differential components were screened, among which 24 constituents(13 homoisoflavonoids and 11 steroidal saponins) were identified via HPLC-LTQ-Orbitrap MS.As a result, it was revealed that different drying methods had significant influences on the components of steroidal saponins and homoisoflavonoids. Among them, 50 ℃-drying method was the most suitable drying approach when the stability of components, cost and practicability were considered.

[Rapid characterization of constituents absorbed into blood after oral administration of steroidal saponins from Radix Ophiopogonis using UHPLC-LTQ-Orbitrap MS coupled with higher energy collision induced dissociation].

The method of UHPLC-LTQ-Orbitrap mass spectrometry coupled with higher energy collision dissociation (HCD) was established to rapidly analyze the constituents absorbed into blood after oral administration of steroidal saponins from Radix Ophiopogonis. A total of 31 constituents, including 13 furostanol steroidal saponins and 18 spirostanol steroidal saponins, were characterized based on the accurate mass measurements, fragmentation patterns, chromatographic retention times, and diagnostic product ions. Among them, 8 compounds were unambiguously identified by comparison with their corresponding standards. The results provide comprehensive insights and guidance for elucidation of material basis of Radix Ophiopogonis activity.

Rapid screening and identification of target constituents using full scan-parent ions list-dynamic exclusion acquisition coupled to diagnostic product ions analysis on a hybrid LTQ-Orbitrap mass spectrometer.

A highly sensitive and effective strategy for rapid screening and identification of target constituents has been developed using full scan-parent ions list-dynamic exclusion (FS-PIL-DE) acquisition coupled to diagnostic product ions (DPIs) analysis on a hybrid LTQ-Orbitrap mass spectrometer. The FS-PIL-DE was adopted as a survey scan to trigger the MS/MS acquisition of all the predictable constituents contained in traditional Chinese medicines. Additionally, DPIs analysis can provide a criterion to judge the target constituents detected into certain chemical families. Results from analyzing polymethoxylated flavonoids (PMFs) in the leaves of Citrus reticulata Blanco demonstrated that FS-PIL-DE was capable of targeting a greater number of constituents than FS, FS-PIL and FS-DE, thereby increasing the coverage of constituent screening. As a result, 135 PMFs including 81 polymethoxyflavones, 54 polymethoxyflavanones or polymethoxychalcones were identified preliminarily. And this was the first time to systematically report the presence of PMFs in the leaves of Citrus reticulata Blanco, especially for polymethoxylated flavanones and chalcones, most of which were new compounds. The results indicated that the developed FS-PIL-DE coupled to DPIs analysis methodology could be employed as a rapid, effective technique to screen and identify target constituents from TCMs extracts and other organic matter mixtures whose compounds contained can also be classified into families based on the common carbon skeletons.

[Mass spectrum characterization of five valepotriates by electrospray ionization tandem mass spectrometry].

OBJECTIVE: To discuss mass spectrum characterization of five valepotriates including 'monoene' type (didrovaltrate), 'diene' type (valtrate, acevaltrate) and 'four-olefinic' type (baldrinal and homobaldrinal) by electrospray ionization tandem mass spectrometry (ESI-MS(n)). METHOD: This study was carried out on the basis of electrospray ionization tandem mass spectrometric method and analysis of multistage fragments. RESULT: The fragmentation patterns and structural assignment of 'monoene' type, 'diene' type and 'four-olefinic' type valepotriates in ESI-MSn under positive mode were summarized. CONCLUSION: The compounds have a strong pyrolysis rules and it can provide reference date for valepotriates in rapid structural identification, quantitative analysis and pharmacokinetic study.

[Occurrence and distribution of volatile organic compounds in conventional and advanced drinking water treatment processes].

A series of experiments were conducted to study the occurrence and distribution of volatile organic compounds (VOCs) in conventional and advanced drinking water treatment processes of 3 water treatment plants in Lianyungang City. Results showed that 30 compounds of 3 classes were detected from 67 kinds of VOCs in all the samples collected. The concentrations of carbonyl compounds, halogenated hydrocarbons and benzenes detected were in the ranges of 0.04-61.27, 0.02-35.61 and 0.07-2.33 microg x L(-1) respectively. Comparing the changes of different VOCs in three drinking water treatment plants, conventional chlorination process could effectively remove benzenes but meanwhile produced trihalomethanes (THMs). Additional advanced treatment ozonation-biological activated carbon process could decrease the formation of THMs during pre-chlorination but produced new risky contaminants like carbonyl compounds. The changes of VOCs in tap water were also investigated. It was found that carbonyl compounds produced by ozonation could be further transformed to THMs with residual chlorine. However, the health risks of all detected compounds in tap water were at a low level, except that the carcinogenic risk of crotonaldehydes (9.3 x 10(-5)-2.2 x 10(-4)) was slightly higher than the US EPA threshold (10(-6)-10(-4)).

[New method to assess phosphorus bioavailability in the sediments and soils].

A new method to assess phosphorus bioavailability in the sediments and soils was developed by using a homemade iron oxide/ cellulose acetate membrane(FeO/CAM). The results show that the amount of bioavailable phosphorus(FeO-P) desorbed from the sediment and soil increased with the shaking time,and FeO-P desorption would come to equilibrium after 16 ot 20h. With the increase of the ratio between soil mass and water volume, the quantity of the desorbed FeO-P would decrease and then went planar after 20 to 30g/L. The quantity of the desorbed FeO-P had no significant difference between the FeO/CAMs of 20 to 30cm2. The dynamics of FeO-P desorption from the sediments and soils would be accelerated by appropriately increasing the shaking frequency. In short, FeO/ CAMs overcome many disadvantages of iron oxide impregnated filter paper and are easy to be commercialized; therefore it may have a better future in the application to assessing phosphorus hioavailability in the sediments and soils.

Origins and mobility of phosphorus forms in the sediments of Lakes Taihu and Chaohu, China.

Phosphorus release from the sediment is generally an important factor for lake eutrophication. We have investigated phosphorus forms in surface sediments from Lake Taihu and Lake Chaohu by a chemical extraction method. The results showed that the concentrations of Fe/Al-bound phosphorus (Fe/Al-P) and organic phosphorus (Org-P) had significant correlations with those of amorphous Fe/Al oxides and organic matter in the sediments. Furthermore, Ca-bound phosphorus (Ca-P) concentrations were well related to total organic carbon (TOC) concentrations. The results also indicated that higher pH weakened the association of phosphates with the Fe/Al hydroxides and then resulted in Fe/Al-P release. The increase of pH was companied with autogenetic progresses of calcium carbonate and then elevated Ca-P concentrations in the sediments. In conclusion, external P loadings determine spatial distribution of P fractions, especially Fe/Al-P and Org-P, and partially contribute to additional Ca-P fractions in these highly human-disturbed lakes. The pH-induced phosphorus mobility in the sediments is very important for these lakes.