Combined Use of Zero Valent Iron and Magnetic Separation for ex-situ Removal of Bioavailable Metals from Contaminated Sediments

Sandy and organic sediments characterized by different heavy metal binding capacities (HMBC), and contaminated with Copper (Cu), mercury (Hg), or zinc (Zn) were treated ex-situ using a remediation approach consisting of (i) sorption onto oxidized zero-valent iron (ZVI) surfaces and (ii) retrieval of formed metal-ZVI complexes from sediment matrices by magnetic separation. The research focused on the reduction/elimination of the bioavailable fractions of metals, and the efficiency of the method assessed by a combination of a bacterial (MetPLATE?) and an invertebrate (the 48-h Ceriodaphnia dubia acute toxicity test) based bioassays. In sandy sediments, characterized by low HMBC (20.8, 23.5, and 39.6 for Hg, Cu, and Zn, respectively), the determined toxicity units (TU) prior to sediment treatment increased in the order Hg < Cu < Zn, regardless of the bioassay used. The use of ZVI and magnetic separation in these sandy sediments resulted in up to 97% TU reduction. In organic-rich sediments, the affinity of the studied metals for organic matter (OM) resulted in much higher HMBC values (83.9, 108.3, and 136.2 for Cu, Zn, and Hg, respectively) and much lower TU values before sediment treatment with ZVI. The use of MetPLATE? on non-treated sediments resulted in TU values increasing in the order Hg < Cu < Zn, with TU removal efficiencies ranging from 83% to 97% after treatment. The TU values measured with the 48-h C. dubia assay were higher than those obtained with MetPLATE?, and in this case, sediments contaminated with Zn exhibited the lowest percentage of TU removal, with only 81.7% and 80.5% TU removal for sediments with contamination levels of 400 and 800 mg/kg, respectively. For organic sediments contaminated with Cu and Hg, the TU removal exceeded 95%. Overall, this study showed that the proposed remediation method has great potentials with regard to the elimination of the bioavailable metal fractions in contaminated sediments.     

In-Situ Bioremediation of DDTs and PAH Contaminated Aging Farmland Soil Using Blood Meal

The use of blood meal was studied for in-site bioremediation of contaminated farmland soil. The combination of blood meal and indigenous microorganisms helped to in-site remediate the combined contaminated aging farmland soil of DDTs and PAH in Shenyang, China. The concentration of DDTs and PAHs was 47.94 ± 0.63 μg/kg and 690.10 ± 5.16 μg/kg, respectively. Biostimulation using blood meal or glucose promoted the bioremediation rate of DDTs and PAHs. Compared to glucose, blood meal was a longer term repair additive of DDTs and PAHs, and the remediation result was more efficient and durable. In the blood meal treatment, plowing the soil once every 7 days could increase the soil enzyme activities and bacterial populations, and it could significantly promote the remediation rates of DDTs (P < 0.05) and more evidently promote the remediation rates of PAHs. The DDTs and PAHs remediation rates increased from 32.18% and 20.17% to 43.41% and 26.09%, respectively, in soil treated with blood meal and plowed weekly after the five month remediation. This study provides an highly efficient in-site farmland soil bioremediation technology that could have practical utility.     

Pollution characteristics and ecological risk assessment of heavy metals in the surface sediments from a source water reservoir

Surface sediment samples were collected from a source water reservoir in Zhejiang Province, East of China to investigate pollution characteristics and potential ecological risk of heavy metals. The BCR sequential extraction method was used to determine the four chemical fractions of heavy metals such as acid soluble, easily reducible, easily oxidizable and residual fractions. The heavy metals pollution and potential ecological risk were evaluated systematically using geoaccumulation index (I_geo) and Hakanson potential ecological risk index (H′). The results showed that the sampling sites from the estuaries of tributary flowing through downtowns and heavy industrial parks showed significantly (p < 0.05) higher average concentrations of heavy metals in the surface sediments, as compared to the other sampling sites. Chemical fractionation showed that Mn existed mainly in acid extractable fraction, Cu and Pb were mainly in reducible fraction, and As existed mainly in residual fraction in the surface sediments despite sampling sites. The sampling sites from the estuary of tributary flowing through downtown showed significantly (p < 0.05) higher proportions of acid extractable and reducible fractions than the other sampling sites, which would pose a potential toxic risk to aquatic organisms as well as a potential threat to drinking water safety. As, Pb, Ni and Cu were at relatively high potential ecological risk with high I_geo values for some sampling locations. Hakanson potential ecological risk index (H′) showed the surface sediments from the tributary estuaries with high population density and rapid industrial development showed significantly (p < 0.05) higher heavy metal pollution levels and potential ecological risk in the surface sediments, as compared to the other sampling sites.     

Tenax TA extraction to understand the rate-limiting factors in methyl-β-cyclodextrin-enhanced bioremediation of PAH-contaminated soil

The effectiveness of many bioremediation systems for PAH-contaminated soil may be constrained by low contaminant bioaccessibility due to limited aqueous solubility or large sorption capacity. Information on the extent to which PAHs can be readily biodegraded is of vital importance in the decision whether or not to remediate a contaminated soil. In the present study the rate-limiting factors in methyl-β-cyclodextrin (MCD)-enhanced bioremediation of PAH-contaminated soil were evaluated. MCD amendment at 10 % (w/w) combined with inoculation with the PAH-degrading bacterium Paracoccus sp. strain HPD-2 produced maximum removal of total PAHs of up to 35 %. The desorption of PAHs from contaminated soil was determined before and after 32 weeks of bioremediation. 10 % (w/w) MCD amendment (M2) increased the Tenax extraction of total PAHs from 12 to 30 % and promoted degradation by up to 26 % compared to 6 % in the control. However, the percentage of Tenax extraction for total PAHs was much larger than that of degradation. Thus, in the control and M2 treatment it is likely that during the initial phase the bioaccessibility of PAHs is high and biodegradation rates may be limited by microbial processes. On the other hand, when the soil was inoculated with the PAH-degrading bacterium (CKB and MB2), the slowly and very slowly desorbing fractions (F _sl and F _vl ) became larger and the rate constants of slow and very slow desorption (k _sl and k _vl ) became extremely small after bioremediation, suggesting that desorption is likely rate limiting during the second, slow phase of biotransformation. These results have practical implications for site risk assessment and cleanup strategies.     

Influence of Celery on the Remediation of PAHs-contaminated Farm Soil

Polycyclic aromatic hydrocarbons (PAHs) contamination has been considered as one of the major environmental concerns for farmland soil all over the world including China. Due to small per capita land area, to find crops or vegetable, which could not only degrade the PAHs contaminants but also would not concentrate PAHs, was particularly important. Celery was selected as the phytoremediator in this experiment, and the soil enzyme activity, PAHs-degrading microorganisms, and the speciation of PAHs in soil were studied. The results showed that celery could significantly enhance the remediation of PAHs compared with the controlled experiment after 90 days (p< 0.01), and the removal efficiency were 31.29%, 30.79%, and 50.21% in the soil, non-rhizosphere soil, and rhizosphere soil, respectively. The soil enzyme activity and PAHs-degrading microorganisms significantly increased in rhizosphere soil compared with non-rhizosphere soil (p< 0.05), and the bioaccessibility of PAHs in soil could have been enhanced in the presence of celery root exudates. Those would help the bioremediation of PAHs by soil microorganisms. Meanwhile, the concentration of PAHs in the edible portion of celery was only 17.13 ± 1.24 μg/kg, and the bioconcentration factors in the aboveground part of celery were only 0.025. This study provides a potential in-site farmland soil phytoremediation technology that could have practical utility.     

Polycyclic aromatic hydrocarbons (PAHs) in the environment of Beijing,China: Levels,distribution, trends and sources

Polycyclic aromatic hydrocarbons (PAHs) have become a major type of persistent organic pollutant (POPs) in the world. To well understand the occurrence, spatial distribution and source apportionment of 16 PAHs in different media in Beijing, a comprehensive study was conducted based on 337 obtained and subsequently selected samples in four specific media, including soil, road dust, surface water and atmosphere covering sampling time spanning from 2005 to 2014. Mean concentrations of Σ16 PAHs in soils (878.5 μg/kg) decreased from inner city to exterior areas with different land uses decreased in the order of industrial estate (2510 μg/kg)>educational area (1331 μg/kg)>Park (783 μg/kg)>cultivated (650 μg/kg)>roadside (583 μg/kg)>residential (568 μg/kg)>green area (478 μg/kg)>forest area (125 μg/kg). Meanwhile, PAHs concentrations in branch roads were slightly higher than trunk roads and mainly concentrated in urban areas (1136 μg/kg). Affected by industrial and residential areas, PAHs concentrations in downstream surface rivers were much higher than upstream surface rivers (475 ng/L). Due to strong mobility, PAHs concentrations in atmosphere were not equally distributed around the study area (157.59 ng/m³). The result of source apportionment determined by diagnostic ratios method indicated PAHs in multiple media in Beijing are mainly from coal and biomass combustion.     

Removal of Nonvolatile Hydrophobic Compounds from Artificially and Naturally Contaminated Soils by Column Flotation

Removal of a nonvolatile paraffin oil from spiked soils using column flotation with countercurrent bubbles was explored at both ambient and elevated temperatures. Up to 80% of the contaminant was separated from the coarse fraction (250 to 800?µm) by flotation at 45°C using aqueous solutions of anionic and nonionic surfactants or alkali salt as collectors. With the 75 to 800?µm fraction, removal efficiencies of up to 65% was achieved. Sodium dodecyl-sulfate and Triton 100X at 50?ppm concentrations as well as sodium carbonate at pH 10 were found to yield similar removal efficiencies. Same surfactants were tested in soil washing experiments at similar and higher dosages. Removal efficiency by flotation was higher than those obtained by soil washing in all cases. In addition, as high surfactant dosage are not used in flotation, unlike in the case of soil washing, the problem of formation of stable emulsions was absent. Experiments with soil polluted by hydrocarbons from a contaminated site demonstrated the feasibility of the flotation process for decontamination of coarse (250 to 830?µm) fractions. A 70% reduction of petroleum hydrocarbon in soil was achieved as a result of flotation at 45°C using the above surfactants.     

Seasonal variations of metal pollution and distribution,sources, and ecological risk of polycyclic aromatic hydrocarbons (PAHs) in sediment of the Al Hawizah wetland,Iran

The pollution of surface sediments of Al Hawizah wetland by metals and polycyclic aromatic hydrocarbons (PAHs) has been fully investigated. For determination of PAHs and metals concentration in sediments, eight sampling stations were selected in the study area. The results showed that the concentration of Mn is the highest, while the content of Cr is the lowest in both the seasons. The concentration of Cr and V is lower than mean crust content, while Cu concentration is more than mean crust content. The results obtained from Muller's geochemical index are indicative of range from uncontaminated to moderately contaminated. Based on potential ecological risk (RI), the Al Hawizah wetland had low ecological risk. The total PAHs concentrations ranged from 1071 to 15540 ng/g dry weight, with a mean of 9417.50 ng/g in the summer, while total amounts of PAHs in the winter ranged from 1542 to 17283 with a mean 10321.25 ng/g dry weight. The area of study was affected by pyrogenic and petrogenic sources (51.74 and 48.26%, respectively), in the winter. The concentrations of polycyclic aromatic hydrocarbons (PAHs) compounds were lower than effects range median (ERM) standard while were higher than effects range low (ERL) standard, except station 1, in both seasons.     

Optimization of Operating Parameters for the Selective Flotation of Heavy Metals from Contaminated Fine Sediment Using Response Surface Model

In this study, the effect of different flotation operating variables, such as pH, pulp density, collector concentration, impeller speed, frother concentration, and air flow rate, on selective flotation of heavy metals, especially Cu, from fine dredged sediment has been evaluated. Parameter optimization was done using the single parameter at a time method and response surface method (RSM) using Box-Behnken design and was assessed in terms of metal removal, metal recovery, metal concentration factor, and mass recovery. Among the operating variables studied, pulp pH, collector concentration, pulp density, and impeller speed were found to have significant effect on metal flotation selectivity. A validation study of the response surface model showed its aptness to predict the optimum values of operating parameters and their interactions on flotation responses which evaluate flotation performance. Flotation experiments under optimum operating parameters showed good flotation selectivity for Cu (3.3 ± 0.2) with a mass recovery of (mass of sediment in the froth) 14.1 ± 1 and Cu removal of 37.4 ± 3.6%.     

Microdistribution of major to trace elements between roots of Halimione portulacoides and host sediments (Tagus estuary marsh,Portugal)

Aim

This study presents a micrometre-scale map of the elemental distribution within roots and surrounding sediment of Halimione portulacoides of a contaminated salt marsh in the Tagus estuary.

Methods

Microprobe particle induced X-ray emission analysis was performed in sediment slices containing roots with tubular rhizoconcretions attached to host sediments.

Results

Strong concentration gradients were found particularly in the inner part of rhizoconcretions adjacent to the root wall. Local enrichment was observed in sediment interstices with Fe precipitates and other associated elements. A maximum of 55 % of Fe was measured near the concretion–root interface, with a decrease to <5 % in the host sediment. Maximum concentrations of P (3 %), As (1,200 μg g^?1) and Zn (3,000 μg g^?1) were registered in concretions, one order of magnitude above the values of the host sediment. The elemental concentration profiles across roots showed that the epidermis was an efficient selective barrier to the entrance of elements. Fe and As were retained in the epidermis. The highest Cu and Zn concentrations were also observed in the epidermis. However, the concentrations of Mn, Cu and Zn increased in the inner root.

Conclusions

As and Fe were mostly retained in the concretion, whereas P, Mn, Cu and Zn were mobilised by the root.     

Evaluation of Heavy Metals Pollution Loadings in the Sediments of the Ave River Basin (Portugal)

Sediment samples from the Ave river basin were collected with the aim of determining metal total pollution contents. Cr, Cu, Fe, Mn, Pb, Zn and VM at 550 °C were determined. Some physico-chemical parameters were also quantified in water samples collected in the water column just above the sediments.

Metal contamination factors (CF) indicated that sediments were not contaminated with Cu and Pb, slightly with Zn and moderately with Cr.

For sediments with high metal pollution loadings, the original BCR (Community Bureau of Reference) metal speciation protocol was also applied. Speciation studies showed that chromium was mainly associated with the oxidisable plus residual fractions (>85%). These results suggest that changes in the physico-chemical properties of the river water (e.g. pH, Eh) should not be accompanied by a significative release of chromium from sediments.

The relationships between chromium speciation fractions, physic-chemical parameters of the sediments and water samples were studied by Principal Component Analysis, and allowed to reduce the dimensionality of the data matrix from 14 to 3 significant components accounting for 89% of the variance. It was found that hydrous Fe/Mn oxides and organic matter are the “carriers” of chromium associated to fractions exchangeable and oxidable.     

Organic acids,amino acids compositions in the root exudates and Cu-accumulation in castor (Ricinus communis L.) Under Cu stress

Ricinus communis L. is a hyperaccumulation plant newly discovered in an abandoned land of Cu mine in China. A hydroponic experiment was then carried out to determine the root exudates in the Cu-tolerant castor (Ricinus communis L.). Plants were grown in nutrient solution with increasing level of Cu doses (0, 100, 250, 500, and 750 μmol/L Cu) in the form of CuSO₄. Cu accumulation in the roots and shoots of castor, and root exudates collected from the castor were measured. The results indicated that the castor had a high Cu accumulation capacity and the Cu concentrations in the shoots and roots of the castor treated with 750 μmol/L Cu were 177.1, 14586.7 mg/kg, respectively. Tartaric was the largest in the root exudates in terms of concentrations, which reached up to 329.13 μmol/g (dry plant) in the level of 750 μmol/L Cu. There was a significantly positive linear relationship between the Cu concentration in root and the concentration of succinic (R = 0.92, P < 0.05), tartaric (R = 0.96, P < 0.01), and citric (R = 0.89, P < 0.05). These results indicated that the difference in root exudation from castor could affect their Cu tolerance. What is more, significant is that the high tartaric and citric, the low oxalic and cysteine in the root exudation of castor contributed to toleration of high Cu concentrations.     

Heavy Metals (Cd,Cu, Ni,Pb, and Zn) Fractionation in River Sediments,Hamedan, Western Iran

Five heavy metals (Cd, Cu, Ni, Pb, and Zn) in river sediments from Abshineh River, Hamedan, western Iran, were fractionated by a sequential extraction procedure. Cu, Ni, Pb, and Zn existed in sediments mainly in residual fraction (mean 92%, 86%, 77%, and 65%, respectively), whereas Cd occurred mostly as organic matter (mean 41%) and exchangeable (mean 25%) fractions. The mean percent of mobile fraction of Cd, Cu, Ni, Pb, and Zn in contaminated sediments was 25, 13, 4, 24, and 10, respectively, which suggests that the mobility and bioavailability of the five metals in sediments probably decline in the following order: Cd = Pb > Cu > Zn > Ni. The metal levels were also evaluated according to the contamination factor, which revealed significant anthropogenic pollution of Cd and Pb.     

Determination of Glyphosate and AMPA in Three Representative Agricultural Austrian Soils with a HPLC-MS/MS Method

We developed a novel method to quantify adsorbed glyphosate and AMPA in soils based on an extraction utilizing Na-tetraborate, an SPE clean-up step, and subsequent LC-MS detection. Reversed phase-based separation of glyphosate and AMPA was realized after FMOC-derivatization. The quantification involved external calibration and 1,2–¹³C, ¹⁵N- labeled glyphosate as well as ¹³C, ¹⁵N labeled AMPA as internal standards. The optimum recovery for extraction was obtained with 40 mM Na-tetraborate. The method was applied in three representative soils (Kirchberg, Phyra, and Pixendorf, Austria) where glyphosate was applied by standard agricultural practices. The recovery for glyphosate extracted with 40 mM Na-tetraborate buffer was 93.5% (RSD <2%) for glyphosate at Kirchberg-cambisol; 95.7% (RSD < 2%) at Pixendorf- chernozem and 79.1% (RSD <7%) at Phyra-stagnosol. The corresponding values for AMPA were 92.4% (RSD <2%) at Kirchberg, 98.1% (RSD <2%) at Pixendorf and 69.9% (RSD <4%) at Phyra. The limits of detection for glyphosate were 6.8 μg kg^?1(RSD <10%) at Kirchberg, 4.3 μg kg^?1 (RSD <10%) at Pixendorf, and 46.5 μg kg^?1 (RSD <7%) at Phyra. The limits of detection for AMPA were 26.7 μg kg^?1 (RSD <10%) at Kirchberg, 25.2 μg kg^?1 (RSD <10%) at Pixendorf, and 120.3 μg kg^?1 (RSD <9%) at Phyra. Accordingly, the limits of quantification were 22.7 μg kg^?1(RSD <5%) for glyphosate, and 88.9 μg kg^?1 (RSD <2%) for AMPA at Kirchberg and respectively 14.4 μg kg^?1 (RSD <6%) and 84 μg kg^?1 (RSD <5%) at Pixendorf and 13.8 μg kg^?1 (RSD <6%) and 87.2 μg kg^?1 (RSD <8%) at Phyra. Both substances in the soils were lower than the LOQ before applying the herbicide Roundup. The influence of higher contents of iron oxides, clay, and acidic pH, resulting in a more pronounced adsorption of glyphosate and AMPA in the soils of Phyra and Kirchberg, is demonstrated.     

Cu(Nor)2·5H2O, a complex of Cu(II) with Norfloxacin: theoretic approach and biological studies. Cytotoxicity and genotoxicity in cell cultures

Norfloxacin is a fluoroquinolone antibiotic used in the treatment of bacterial infections. In this article, we studied the potential antitumoral action of a complex of Norfloxacin with Cu(II), Cu(Nor)₂·5H₂O on osteosarcoma cells (UMR106) and calvaria-derived cells (MC3T3-E1), evaluating its cytotoxicity and genitoxicity. We have also elucidated the more stable conformation of this complex under physiologic conditions by Molecular Dynamic simulations based on the model of the canonical ensemble and PM6 force field. When solvent effect was taken into account, the complex conformation with both carbonyl groups in opposite sides displayed lower energy. Cu(Nor)₂·5H₂O caused an inhibitory effect on the proliferation on both cell lines from 300 μM (P < 0.01). Nevertheless, the decline on cell proliferation of UMR106 cells was more pronounced (45 % vs basal) than in MC3T3-E1 cells (20 % vs basal) at 300 μM (P < 0.01). Cu(Nor)₂·5H₂O altered lysosomal metabolism (Neutral Red assay) in a dose-dependent manner from 300 μM (P < 0.001). Morphological studies showed important transformations that correlated with a decrease in the number of cells in a dose-dependent manner. Moreover, Cu(Nor)₂·5H₂O caused statistically significant genotoxic effects on both osteoblast cell lines in a lower range of concentrations (Micronucleus assay) (P < 0.05 at 10 μM, P < 0.001 from 25 to 50 μM). UMR106 cells displayed a dose-related genotoxic effect between 5 and 25 μM while the MC3T3-E1 cells showed a narrower concentration dependent range. Altogether, these results suggest that Cu(Nor)₂·5H₂O is a good candidate to be further evaluated for alternative therapeutics in cancer treatment.     

Polycyclic Aromatic Hydrocarbons in Surface Soils of Kunming,China: Concentrations,Distribution, Sources,and Potential Risk

The concentrations, distribution, possible sources, and potential risk of polycyclic aromatic hydrocarbons (PAHs) in surface soils were studied in Kunming, which is situated in a lake basin of the Yunnan-Guizhou plateau. 15 PAHs were analyzed in 40 surface soil samples (0–5 cm layer) collected from six types of land uses in the Kunming urban area. Meanwhile, the potential sources of PAHs in surface soils of Kunming were investigated by PAH composition ratios, isomer ratios, and principal component analysis (PCA). The total concentrations of 15 PAHs ranged from 101.64 to 6,208.25 ng/g (dry weight basis). The concentrations in different land uses increased in an order as: green space (541.43 ng/g) < education area (756.49 ng/g) < business area (810.17 ng/g) < residential area (1,034.36 ng/g) < industrial area (1,166.79 ng/g) < roadside greens (2,146.76 ng/g). The results of sources identification suggested that PAHs in surface soils of the Kunming urban area were greatly affected by combustion activities which came mainly from coal combustion and vehicular traffic. In addition, the toxic equivalency factors (TEFs) were used to estimate benzo[a]pyrene-equivalent concentration in surface soils of Kunming, and the risk level of PAHs in Kunming's urban surface soils was low as a whole.     

Soil organic carbon dynamics 75 years after land-use change in perennial grassland and annual wheat agricultural systems

The dynamics of roots and soil organic carbon (SOC) in deeper soil layers are amongst the least well understood components of the global C cycle, but essential if soil C is to be managed effectively. This study utilized a unique set of land-use pairings of harvested tallgrass prairie grasslands (C₄) and annual wheat croplands (C₃) that were under continuous management for 75 years to investigate and compare the storage, turnover and allocation of SOC in the two systems to 1 m depth. Cropland soils contained 25 % less SOC than grassland soils (115  and 153 Mg C ha^?1, respectively) to 1 m depth, and had lower SOC contents in all particle size fractions (2000–250, 250–53, 53–2 and <2 μm), which nominally correspond to SOC pools with different stability. Soil bulk δ¹³C values also indicated the significant turnover of grassland-derived SOC up to 80 cm depth in cropland soils in all fractions, including deeper (>40 cm) layers and mineral-associated (<53 μm) SOC. Grassland soils had significantly more visible root biomass C than cropland soils (3.2 and 0.6 Mg ha^?1, respectively) and microbial biomass C (3.7 and 1.3 Mg ha^?1, respectively) up to 1 m depth. The outcomes of this study demonstrated that: (i) SOC pools that are perceived to be stable, i.e. subsoil and mineral-associated SOC, are affected by land-use change; and, (ii) managed perennial grasslands contained larger SOC stocks and exhibited much larger C allocations to root and microbial pools than annual croplands throughout the soil profile.     

Effects of amlodipine and adenosine on coronary haemodynamics: in vivo study and numerical simulation

Amlodipine (AMLO) is a calcium channel blocker with vasodilating properties, in which the specific effects on the coronary circulation are not fully known. Coronary flow velocity–pressure (F/P) curves were obtained at rest and during administration of AMLO (10 mg to 20 mg iv) or adenosine (ADO, 1 mg ic) in 10 normal subjects (six women, age 48 ± 14 years). F/P curves were reproduced in a numerical simulator of systemic and coronary circulations (CARDIOSIM^©) by adjustment of coronary resistance ( > or < 100 μm diameter vessels) and extravascular resistance applied to smaller vessels at endocardial (ENDO), middle and epicardial (EPI) myocardial layers. Best matching of in silico to in vivo curves was achieved by trial and error approach. ADO induced 170% and 250% increase in coronary flow velocity CFV and F/P diastolic slope as compared to 80% and 25–30% increase induced by AMLO, respectively. In the cardiovascular model, AMLO effects were predicted by progressive reduction of>100 μm vessels resistance from EPI to ENDO. ADO effects were mimicked by reducing resistance of both>100 μm and < 100 μm vessels, progressively from EPI to ENDO in the latter. Additional reduction in extravascular resistance avoided to impose a transmural gradient of vasodilating effect for both drugs. Numerical simulation predicts vasodilating effects of AMLO mainly on larger arteries and of ADO on both>and < 100 μm vessels. In vivo F/P loops could be completely reproduced in silico by adding extravascular resistance reduction for both drugs. Numerical simulator is useful tool for exploring the coronary effects of cardioactive drugs.     

Influence of anthropogenic activities on polycyclic aromatic hydrocarbons in sediments from mangrove wetland at Dongzhai Harbor,China: distribution,sources, probability risk,and temporal trend

Sixteen polycyclic aromatic hydrocarbons (PAHs) in 37 surface sediments and a sediment core from the Dongzhai National Nature Reserve in Hainan island of China were analysed. The total concentration of the 16 PAHs ranged from 15.7 to 464.0 ng g^?1 (mean value of 76.7 ng g^?1) in the surface sediments, and 8.6–115.9 ng g^?1 (average 39.3 ng g^?1) in the sediment core. Combustions of petroleum, biomass, coal, and grass were the major pyrogenic sources in surface sediments, and some areas had petrogenic sources (mainly petroleum spills). Results of the ecological risk assessment show little negative effect of most of the PAHs in the study area. The depositional flux of PAHs generally increased from the deeper layers toward the upper layers of the sediments. The flux rate rapidly increased after the 1980s, in contrast to that of some developed countries.     

Simultaneous Desorption and Desorption Kinetics of Phenanthrene,Anthracene, and Heavy Metals from Kaolinite with Different Organic Matter Content

Soils contaminated simultaneously with polycyclic aromatic hydrocarbons (PAHs) and heavy metals pose major threat to human health and environment by getting released from soil into water environment. The purpose of this study was to evaluate simultaneous desorption and desorption kinetics of PAHs (phenanthrene and anthracene) and heavy metals (lead, nickel, and zinc) from artificially contaminated kaolinite soils with different organic matter content. Batch desorption tests were conducted using single and combined enhancing agents containing Triton X-100 and Tween 80 as non-ionic surfactants, Ethylenediaminetetraacetic acid (EDTA) as a chelating agent, and citric acid as an organic acid. The solution with the highest removal efficiency was the combined solution of Triton X-100 (10% w/w) + EDTA (0.01 M). Removal levels around 92, 46, 92, 95, and 96% were obtained for phenanthrene, anthracene, lead, nickel, and zinc, respectively, by using this combination. Batch desorption kinetics experiments were performed using the mentioned combination. During the first 24 h, desorption kinetics were rapid, followed by a plateau until the end. The data obtained from desorption kinetics experiments were fitted with four kinetics models: pseudo-second-order equation, empirical power function, elovich, and parabolic diffusion. The correlation coefficient of the pseudo-second-order equation was higher than that of other functions. Moreover, batch experiments have showed inverse correlations between removal efficiency and organic matter content of soil.