Biodegradation of phthalate esters in polluted soil by using organic amendment

This study investigated the biodegradation of the phthalate esters (PAEs) di-n-butyl phthalate (DBP) and di-(2-ethyl hexyl) phthalate (DEHP) in sludge and sludge-amended soil. DBP (100 mg kg(-1)) and DEHP (100 mg kg(-1)) were added to sewage sludge, which was subsequently added to soil. The results showed that sewage sludge can degrade PAEs and the addition of sewage sludge to soil enhanced PAE degradation. Sludge samples were separated into fractions with various particle size ranges, which spanned 0.1-0.45 μm to 500-2000 μm. The sludge fractions with smaller particle sizes demonstrated higher PAE degradation rates. However, when the different sludge fractions were added to soil, particle size had no significant effect on the rate of PAE degradation. The results from this study showed that microbial strains F4 (Rhodococcus sp.) and F8 (Microbacterium sp.) were constantly dominant in the mixtures of soil and sludge.     

Biodegradation of four phthalate esters in sludge

This study investigated the effects of ultrasonic pretreatment and various treatments on the aerobic degradation of four phthalic acid esters (PAEs) such as diethyl phthalate (DEP), benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP) and di-(2-ethyl hexyl)phthalate (DEHP) in sludge. The effect on PAE degradation of treating sludge with a 20 min sonication period at a power level of 0.1 W ml(-1) was evaluated. The degradation rates of the four PAEs were DBP>BBP>DEP>DEHP. Degradation rate constants (k(1)) and half-lives (t(1/2)) for the four PAEs (50 mg kg(-1)) ranged from 0.182 to 0.379 day(-1) and 1.8 to 3.8 days, respectively. The optimal pH for PAE degradation in sludge was 7.0 at 30 degrees C. PAE degradation was enhanced by the addition of yeast extract, brij 30 or brij 35 and inhibited by the addition of hydrogen peroxide. Our results show that a combination of ultrasonic pretreatment and biodegradation can effectively remove PAE from sludge.     

Biodegradation of phthalate esters by two bacteria strains

In this study two aerobic phthalic acid ester (PAE) degrading bacteria strains, DK4 and O18, were isolated from river sediment and petrochemical sludge, respectively. The two strains were found to rapidly degrade PAE with shorter alkyl-chains such diethyl phthalate (DEP), dipropyl phthalate (DPrP), di-n-butyl phthalate (DBP), benzylbutyl phthalate (BBP) and diphenyl phthalate (DPP) are very easily biodegraded, while PAE with longer alkyl-chains such as dicyclohexyl phthalate (DCP) and dihexyl phthalate (DHP) and di-(2-ethylhexyl) phthalate (DEHP) are poorly degraded. The degradation rates of the eight PAEs were higher for strain DK4 than for strain O18. In the simultaneous presence of strains DK4 and O18, the degradation rates of the eight PAEs examined were enhanced. When the eight PAEs were present simultaneously, degradation rates were also enhanced. We also found that PAE degradation was delayed by the addition of nonylphenol or selected polycyclic aromatic hydrocarbons (PAHs) at a concentration of 1 microg/g in the sediment. The bacteria strains isolated, DK4 and O18, were identified as Sphigomonas sp. and Corynebacterium sp., respectively.     

Rape (Brassica chinensis L.) seed germination, seedling growth, and physiology in soil polluted with di-n-butyl phthalate and bis(2-ethylhexyl) phthalate

Phthalic acid esters (PAEs) pollution in agricultural soils caused by widely employed plastic products is becoming more and more widespread in China. PAEs polluted soil can lead to phytotoxicity in higher plants and potential health risks to human being. We evaluated the individual toxicity of di-n-butyl phthalate (DnBP) and bis(2-ethylhexyl) phthalate (DEHP), two representative PAEs, to sown rape (Brassica chinensis L.) seeds within 72 h (as germination stage) and seedlings after germination for 14 days by monitoring responses and trends of different biological parameters. No significant effects of six concentrations of PAE ranging from 0 (not treated/NT) to 500 mg?kg^?1 on germination rate in soil were observed. However, root length, shoot length, and biomass (fresh weight) were inhibited by both pollutants (except root length and biomass under DEHP). Stimulatory effects of both target pollutants on malondialdehyde (MDA) content, superoxide dismutase (SODase) activity, ascorbate peroxidase (APXase) content, and polyphenoloxidase (PPOase) activity in shoots and roots (SODase activity in shoots excluded) were in the same trend with the promotion of proline (Pro) but differed with acetylcholinesterase activity (except in shoots under DnBP) for analyzed samples treated for 72 h and 14 days. Responses of representative storage compounds free amino acids (FAA) and total soluble sugar (TSS) under both PAEs were raised. Sensitivity of APXase and Pro in roots demonstrates their possibility in estimation of PAE phytotoxicity and the higher toxicity of DnBP, which has also been approved by the morphological photos of seedlings at day 14. Higher sensitivity of the roots was also observed. The recommended soil allowable concentration is 5 mg DnBP?kg^?1 soil for the development of rape. We still need to know the phytotoxicity of DEHP at whole seedling stage for both the growing and development; on the other hand, soil criteria for PAE compounds are urgently required in China.     

Distribution,source, and environmental risk assessment of phthalate esters (PAEs) in water,suspended particulate matter,and sediment of a typical Yangtze River Delta City,China

Phthalates (PAEs) in drinking water sources such as the Yangtze River in developing countries had aroused widespread concern. Here, the water, suspended particulate matter (SPM), and sediment samples were collected from 15 sites in wet and dry seasons in Zhenjiang, for the determination of six PAEs (DMP, DEP, DIBP, DBP, DEHP, and DOP) using the solid-phase extraction (SPE) or ultrasonic extraction coupled with gas chromatography-mass spectrometry (GC-MS). The total concentrations of six PAEs (Σ₆PAEs) spanned a range of 2.65–39.31 μg L^?1 in water, 1.97–34.10 μg g^?1 in SPM, and 0.93–34.70 μg g^?1 in sediment. The partition coefficients (K_d1) of PAEs in water and SPM phase ranged from 0.004 to 3.36 L g^?1 in the wet season and from 0.12 to 2.84 L g^?1 in the dry season. K_d2 of PAEs in water and sediment phase was 0.001–9.75 L g^?1 in the wet season and 0.006–8.05 L g^?1 in the dry season. The dominant PAEs were DIBP, DBP, and DEHP in water and SPM, DIBP, DEHP, and DOP in sediment. The concentration of DBP in water exceeded the China Surface Water Standard. The discharge of domestic sewage and industrial wastewater might be the main potential sources of PAEs. The risk quotient (RQ) method used for the risk assessment revealed that DBP (0.01 < RQ < 1) posed a medium risk, while DIBP and DEHP (RQ > 1) posed a high environmental risk in water, DIBP (RQ > 1) also showed a high risk in sediment.

     

Biodegradation of phthalate esters during the mesophilic anaerobic digestion of sludge

Phthalic acid esters (PAE) are commonly found in the sludge generated in the wastewater treatment plants. Anaerobic digestion followed by land application is a common treatment and disposal practice of sludge. To date, many studies exist on the anaerobic biodegradation rates of PAE, especially of the easily biodegradable ones, whereas the higher molecular weight PAE have reported to be non-biodegradable under methanogenic conditions. Furthermore, there is no information on the effect of the PAE on the performance of the anaerobic digesters treating sludge. In this study, the anaerobic biodegradation of di-n-butyl phthalate (DBP), di-ethyl phthalate (DEP) and di-ethylhexyl phthalate (DEHP) was investigated and their relative rates of anaerobic degradation were calculated. Also, the biological removal of PAE during the anaerobic digestion of sludge in bench-scale digesters was investigated using DBP and DEHP as model compounds of one biodegradable and one recalcitrant PAE respectively. The degradation of all the PAE tested in this study (DEP, DBP and DEHP) is adequately described by first-order kinetics. Batch and continuous experiments showed that DEP and DBP present in sludge are rapidly degraded under mesophilic anaerobic conditions (a first-order kinetic constant of 8.04 x 10(-2) and 13.69 x 10(-2)-4.35 day(-1) respectively) while DEHP is degraded at a rate between one to two orders of magnitude lower (0.35 x 10(-2)-3.59 x 10(-2) day(-1)). It is of high significance that experiments with anaerobic sludge of different origin (US and Europe) showed that degradation of DEHP occurs under methanogenic conditions. Accumulation of high levels of DEHP (more than 60 mg/l) in the anaerobic digester has a negative effect on DBP and DEHP removal rates as well as on the biogas production.     

Effects of film mulching on the distribution of phthalate esters in wheat grains from dryland

The application of plastic film in field crop production elevated the phthalate esters (PAEs) accumulation in wheat grains, which poses potential risks to human health. However, the variation of grain PAEs contents in different dryland areas is not clear, and the distribution of PAEs in different tissues of grains has not been studied yet. In the present study, field experiments in five sites (three provinces) with two treatments (soil with and without film mulching) were carried out to study the concentration and distribution of PAEs in grains and the effects of environmental factors on them. Results showed that the total PAE concentration (∑PAEs) in wheat grains ranged from 445 to 764 μg/kg, mainly in the forms of di-(2-ethylhexyl)-phthalate (DEHP), dibutyl phthalate (DBP), and diisobutyl phthalate (DIBP). Compared with control, total PAE concentrations in soils and wheat grains were significantly higher in treatments with film mulching. The effects of film on the proportion of PAEs in the flour and bran varied with experiment sites. Grain PAEs in the control groups presented significantly negative correlation with annual temperature, while there was a positive correlation between soil PAEs and bran PAEs in the film treatment. Results in this study are of great significance to comprehensively evaluate the effect of film mulching on grain safety in dryland wheat production.

     

Atmospheric deposition of phthalate esters in a subtropical city

In Chinese cities, air pollution has become a serious and aggravating environmental problem undermining the sustainability of urban ecosystems and the quality of urban life. Bulk atmospheric deposition samples were collected two-weekly, from February 2007 to January 2008, at three representative areas, one suburban and two urbanized, in the subtropical city, Guangzhou, China, to assess the deposition fluxes and seasonal variations of phthalate esters (PAEs). Sixteen PAE congeners in bulk deposition samples were measured and the depositional fluxes of ∑₁₆PAEs ranged from 3.41 to 190 μg m^?2 day^?1, and were highly affected by local anthropogenic activities. The significant relationship between PAEs and particulate depositional fluxes (correlation coefficient R² = 0.72, P < 0.001) showed PAEs are associated primarily with particles. Temporal flux variations of PAEs were influenced by seasonal changes in meteorological parameters, and the deposition fluxes of PAEs were obviously higher in wet season than in dry season. Diisobutyl phthalate (DiBP), Di-n-butyl phthalate (DnBP), and Di(2-ethylhexyl) phthalate (DEHP) dominated the PAE pattern in bulk depositions, which is consistent with a high consumption of the plasticizer market in China. PAE profiles in bulk deposition showed similarities exhibited in both time and space, and a weak increase of high molecular weight PAE (HMW PAE) contribution in the wet season compared to those in the dry season. Average atmospheric deposition fluxes of PAEs in the present study were significantly higher than those from other studies, reflecting strong anthropogenic inputs as a consequence of rapid industrial and urban development in the region.     

南京某城市污水二级处理系统中酞酸酯类的分布及去除特征

以南京某城市污水厂污水和污泥中的酞酸酯类（PAEs）为研究对象，分别采用固相萃取-气相色谱-质谱联用（SPE—Gc．Ms）和超声提取．气相色谱．质谱联用（USE—GC—Ms）检测其中的优先控制污染物邻苯二甲酸二甲酯（DMP）、邻苯二甲酸二乙酯（DEP）、邻苯二甲酸二丁酯（DBP）和邻苯二甲酸单（2-乙基己基）酯（MEHP），研究其在厌氧／好氧（A／O）污泥处理过程中的分布特征及降解规律。研究结果表明，各类PAEs在该污水厂的污水和污泥中均有检出，二级处理出水中4种酞酸酯类物质的浓度在0．151—2．419μg／L。污水中4种酞酸酯的分布规律为MEHP〉DBP〉DMP〉DEP，污泥中4种酞酸酯的分布规律为MEHP〉DBP〉DEP〉DMP。该污水厂二级处理工艺对4种PAEs的去除效果较明显，去除效率DBP〉DEP〉DMP〉MEHP．     

Occurrence and microbial degradation of phthalate esters in Taiwan river sediments

Concentrations and microbial degradation rates were measured for eight phthalate esters (PAEs) found in 14 surface water and six sediment samples taken from rivers in Taiwan. The tested PAEs were diethyl phthalate (DEP), dipropyl phthalate (DPP), di-n-butyl phthalate (DBP), diphenyl phthalate (DPhP), benzylbutyl phthalate (BBP), dihexyl phthalate (DHP), dicyclohexyl phthalate (DCP), and di-(2-ethylhexyl) phthalate (DEHP). In all samples, concentrations of DEHP and DBP were found to be higher than the other six PAEs. DEHP concentrations in the water and sediment samples ranged from ND to 18.5 μg/l and 0.5 to 23.9 μg/g, respectively; for DBP the concentration ranges were 1.0–13.5 μg/l and 0.3–30.3 μg/g, respectively. Concentrations of DHP, BBP, DCP and DPhP were below detection limits. Under aerobic conditions, average degradation half-lives for DEP, DPP, DBP, DPhP, BBP, DHP, DCP and DEHP were measured as 2.5, 2.8, 2.9, 2.6, 3.1, 9.7, 11.1 and 14.8 days, respectively; under anaerobic conditions, respective average half-lives were measured as 33.6, 25.7, 14.4, 14.6, 19.3, 24.1, 26.4 and 34.7 days. In other words, under aerobic conditions we found that DEP, DPP, DBP, DPhP and BBP were easily degraded, but DEHP was difficult to degrade; under anaerobic conditions, DBP, DPhP and BBP were easily degraded, but DEP and DEHP were difficult to degrade. Aerobic degradation rates were up to 10 times faster than anaerobic degradation rates.     

Sorption behavior of dibutyl phthalate and dioctyl phthalate by aged refuse

Sorption is a fundamental process controlling the transformation, fate, degradation, and biological activity of hydrophobic organic contaminants in the environment. We investigated the kinetics, isotherms, and potential mechanisms for the sorption of two phthalic acid esters (PAEs), dibutyl phthalate (DBP) and dioctyl phthalate (DOP), on aged refuse. A two-compartment first-order model performed better than a one-compartment first-order model in describing the kinetic sorption of PAEs, with a fast sorption process dominating. Both the Freundlich and Dubinin–Astakhov (DA) models fit the sorption isotherms of DBP and DOP, with the DA model being of a better fit over the range of apparent equilibrium concentrations. The values of the fitting parameters (n, b, E) of the PAEs suggest nonlinear sorption characteristics. Higher predicted partition coefficient values and saturated sorption capacity existed in refuse containing larger quantities of organic matter. The sorption capacity of DOP was significantly higher than that of DBP. PAE sorption was dependent on liquid phase pH. Desorption hysteresis occurred in PAE desorption experiments, especially for the long-chain DOP. PAEs may therefore be a potential environmental risk in landfill.     

Anaerobic degradation of diethyl phthalate, di-n-butyl phthalate, and di-(2-ethylhexyl) phthalate from river sediment in Taiwan

We investigated anaerobic degradation rates for three phthalate esters (PAEs), diethyl phthalate (DEP), di-n-butyl phthalate (DBP), and di-(2-ethylhexyl) phthalate (DEHP), from river sediment in Taiwan. The respective anaerobic degradation rate constants for DEP, DBP, and DEHP were observed as 0.045, 0.074, and 0.027 1/day, with respective half-lives of 15.4, 9.4, and 25.7 days under optimal conditions of 30 °C and pH 7.0. Anaerobic degradation rates were enhanced by the addition of the surfactants brij 35 and triton N101 at a concentration of 1 critical micelle concentration (CMC), and by the addition of yeast extract. Degradation rates were inhibited by the addition of acetate, pyruvate, lactate, FeCl₃, MnO₂, NaCl, heavy metals, and nonylphenol. Our results indicate that methanogen, sulfate-reducing bacteria, and eubacteria are involved in the degradation of PAEs.     

Current status and historical variations of phthalate ester (PAE) contamination in the sediments from a large Chinese lake (Lake Chaohu)

The residual levels of phthalate esters (PAEs) in the surface and two core sediments from Lake Chaohu were measured with a gas chromatograph–mass spectrometer (GC–MS). The temporal–spatial distributions, compositions of PAEs, and their effecting factors were investigated. The results indicated that di-n-butyl phthalate (DnBP), diisobutyl phthalate (DIBP), and di(2-ethylhexyl) phthalate (DEHP) were three dominant PAE components in both the surface and core sediments. The residual level of total detected PAEs (∑PAEs) in the surface sediments (2.146?±?2.255 μg/g dw) was lower than that in the western core sediments (10.615?±?9.733 μg/g) and in the eastern core sediments (5.109?±?4.741 μg/g). The average content of ∑PAEs in the surface sediments from the inflow rivers (4.128?±?1.738 μg/g dw) was an order of magnitude higher than those from the lake (0.323?±?0.093 μg/g dw), and there were similar PAE compositions between the lake and inflow rivers. This finding means that there were important effects of PAE input from the inflow rivers on the compositions and distributions of PAEs in the surface sediments. An increasing trend was found for the residual levels of ΣPAEs, DnBP, and DIBP from the bottom to the surface in both the western and eastern core sediments. Increasing PAE usage with the population growth, urbanization, and industrial and agricultural development in Lake Chaohu watershed would result in the increasing production of PAEs and their resulting presence in the sediments. The significant positive relationships were also found between the PAE contents and the percentage of sand particles, as well as TOC contents in the sediment cores.     

Profiles and risk assessment of phthalate acid esters (PAEs) in drinking water sources and treatment plants,East China

This study is the first report describing the occurrence of 15 phthalate acid esters (PAEs) in the three typical water sources of YiXing City, Taihu Upper-River Basin, East China. The fate of target PAEs in the Jiubin drinking water treatment plant (JTP) was also analyzed. The amounts of Σ₁₅PAE in the Hengshan (HS), Youche (YC), and Xijiu (XJ) water sources were relatively moderate, with mean values of 360, 357, and 697 ng L⁻¹, respectively. Bis(2-ethylhexyl) phthalate (DEHP) dominated the PAE concentration, making up 80% of the 15 total PAEs. The highest levels of Σ₁₅PAE were found in HS, YC, and XJ in March 2015, January 2015, and July 2014, respectively. The occurrence and concentrations of these compounds were spatially dependent, and the mean concentrations of Σ₁₅PAE in HS, YC, and XJ samples increased from the surface layer to the bottom layer with varied percentage increases. The removal efficiency of the PAEs in the finished water varied markedly, and the removal of PAEs by the JTP ranged from 12.8 to 64.5%. The potential ecosystem risk assessment indicated that the risk of PAEs was relatively low in these three water sources. However, risks posed by PAEs due to drinking water still exist; therefore, special attention should be paid to source control in the JTP, and advanced treatment processes for drinking water supplies should be implemented.

     

Atmospheric distribution of particulate- and gas-phase phthalic esters (PAEs) in a Metropolitan City, Nanjing, East China

Phthalic acid esters (PAEs) are used in many branches of industry and are produced in huge amounts throughout the world. An investigation on particulate- and gas-phase distribution of PAEs has been conducted in Nanjing (China). The 12-h daily sampling program (from 8:00 am to 8:00 pm) for ten consecutive days was conducted in April, July and October 2005, and in January 2006 at about 1.5m above the ground level. For comparative purposes, sampling events were simultaneously conducted at two stations, one at the urban center and the other about 12 km from city center for suburban background monitoring. It was observed that the most abundant members of the PAE group were dimethyl phthalate (DMP) (10.1 ng m(-3), average), diethyl phthalate (DEP) (3.4 ng m(-3)), dibutyl phthalate (DBP) (58.8 ng m(-3)), butylbenzyl phthalate (BBP) (3.2 ng m(-3)), di-2-ethylhexyl phthalate (DEHP) (20.3 ng m(-3)) and di-n-octyl phthalate (DOP) (1.2 ng m(-3)). The average contribution of PAEs in the gas phase to the total PAE concentration (Sigma(6)PAE, sum of six PAE congeners) ranged from 75.0% to 89.2%. Both particulate- and gas-phase Sigma(6)PAE concentrations decreased with increasing temperature. Experimentally determined gas-particle partitioning (K(p)) of PAEs is well-correlated with their vapor pressure. The Sigma(6)PAE levels in the urban area are approximately 3.5 times as high as the levels found at the suburban station. The vertical profiles from 1.5 to 30.0m above the ground display slight height dependence.     

Environmental and Potential Health Effects of Growing Leafy Vegetables on Soil Irrigated Using Sewage Sludge and Effluent: A Case of Zn and Cu

Abstract

The use of sewage sludge and effluent as a source of nutrients and water for crop production is increasing worldwide. A study was conducted in 2001 at Pension farm (near Harare) to determine the effect of long term (>30 yrs) application of sewage sludge and effluent on Zn and Cu accumulation in top soil, uptake of these metals by lettuce (Lactuca sativa L.) and mustard rape (Brassica juncea L.), and dry matter yield. Application of sewage sludge/effluent significantly (p < 0.001) increased total Zn (13.7–1563.9 mg kg^?1) and Cu (2.5–133.3 mg kg^?1) in the top soil (0–20 cm depth) compared to the control. Sewage sludge/effluent addition significantly (p < 0.001) increased Zn uptake by both test crops, while Cu uptake was significant in the first crop of lettuce and the second crop of mustard rape. Based on the dietary patterns of poor urban households in Zimbabwe, the maximum possible intake of Cu will only constitute 40% the Maximum Daily Intake (MDI). The toxicological implications for Zn will however be more severe, exceeding the MDI by 77% through exposure by lettuce consumption and by 251% consumption of mustard rape. It was concluded that long-term addition of sewage sludge/effluent to soil at Pension farm had increased the concentration of Zn and Cu in top soil to levels that pose environmental concern. The consumption of leafy vegetables produced on these soils pose a health risk to poor communities that reside around the study site, especially children, through possible Zn toxicity.     

Fast extraction of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran in sewage sludge and soil samples

The current environmental legislations recommend monitoring chemical contaminants such as polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans before the use of sewage sludge on the agricultural land. In this study, a solid–liquid extraction with low-temperature purification (SLE-LTP) was optimized and validated to determine 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in sewage sludge and soil samples. The analyses were performed by gas chromatography-mass spectrometry operating in the selective ion mode (GC-MS-SIM). Acetonitrile:ethyl acetate 6.5:1.5 (v/v) was the best extraction phase, and the recoveries percentages were close to 100%. The linearity was demonstrated in the range of 1.25–25 µg L^?1 of 1.25–20 µg L^?1 for sewage sludge and soil, respectively. Matrix effect was proved for the two compounds and in the two matrices studied. Extraction percentages were between 78 and 109% and relative standard deviations ≤ 19%. The proposed method is faster than methods described in the literature because showed a few steps. The quantification limits (LOQ) in sewage sludge were 6.4 and 32 ng TEQ kg^?1 for 2,3,7,8-TCDF and 2,3,7,8-TCDD, respectively. In soil, LOQs were 0.8 and 8.0 ng TEQ kg^?1 for 2,3,7,8-TCDF and 2,3,7,8-TCDD, respectively. These values are lower than the maximum residue limits established by European Legislation. The method was applied to 22 agricultural soil samples from different Brazilian cities and 2,3,7,8-TCDF was detected in one of these samples.     

Adsorption/Desorption of Copper by a Sandy Soil Amended with Various Rates of Manure,Sewage Sludge,and Incinerated Sewage Sludge

Organic amendments are sometimes applied to agricultural soils to improve the physical, chemical, and microbiological properties of the soils. The organic fractions in these soil amendments also influence metal reaction, particularly the adsorption and desorption of metals, which, in turn, determine the bioavailability of the metals and hence their phytotoxicities. In this study, a Quincy fine sandy (mixed, mesic, Xeric Torripsamments) soil was treated with 0 to 160 g kg^?1 rates of either manure, sewage sludge (SS), or incinerated sewage sludge (ISS) and equilibrated in a greenhouse at near field capacity moisture content for 100 days. Following the incubation period, the soil was dried and adsorption of copper (Cu) was evaluated in a batch equilibration study at either 0, 100, 200, or 400 mg L^?1 Cu concentrations in a 0.01M CaCl₂ solution. The desorption of adsorbed Cu was evaluated by three successive elutions in 0.01M CaCl₂. Copper adsorption increased with an increase in manure rates. At the highest rate of manure addition (160 g kg^?1 soil), Cu adsorption was two-fold greater than that by the unamended soil at all rates of Cu additions. With increasing rates of Cu additions, the adsorption of Cu decreased from 99.4 to 77.6% of Cu applied to the 160 g kg^?1 manure amended soil. The desorption of Cu decreased with an increase in rate of manure amendment. Effects of sewage sludge amendments on Cu adsorption were somewhat similar to those as described for manure additions. Likewise, the desorption of Cu was the least at the high rate of SS addition (160 g kg^?1), although at the lower rates there was not a clear indication of the rate effects. In contrast to the above two amendments, the ISS amendment had the least effect on Cu adsorption. At the highest rate of ISS amendment, the Cu adsorption was roughly 50% of that at the similar rate of either manure or SS amendments, across all Cu rates.     

A miniature stainless steel net dumbbell-shaped stir-bar for the extraction of phthalate esters in instant noodle and rice soup samples

Abstract

This work reports the development of a very-simple-to-construct stir-bar extraction device so called “a dumbbell-shaped stainless steel stir-bar.” The extraction device was assembled from a rolled up stainless steel net filled with an XAD-2 sorbent and a metal rod to allow the use of a magnetic stirrer during extraction. The dumbbell-shaped stainless steel stir-bar was used to extract diethyl phthalate (DEP), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) before analysis by a gas chromatograph equipped with an electron capture detector (GD-ECD). Under the optimal conditions, the developed method provided a good linearity from 10.0 to 1,000.0?ng mL^?1 for all three compounds. Limits of detection and limits of quantification were 9.37?±?0.29?ng mL^?1 and 31.22?±?0.95?ng mL^?1 for DEP, 5.73?±?0.31?ng mL^?1 and 19.1?±?1.0?ng mL^?1 for DBP and 3.30?±?0.06?ng mL^?1 and 11.0?±?0.19?ng mL^?1 for DEHP, respectively. Good recoveries in the range of 81.89?±?0.17 to 109.5?±?2.0% were achieved when the method was used to extract phthalate esters in five instant noodle and two rice soup samples.     

Comparative analysis of trace contaminants in leachates before and after a pre-oxidation using a solar photo-Fenton reaction

Sanitary landfill leachates are a complex mixture of high-strength organic and inorganic persistent contaminants, which constitute a serious environmental problem. In this study, trace contaminants present in leachates were investigated by gas chromatography-mass spectrometry and gas chromatography-flame ionization detector before and after a pre-oxidation step using a solar photo-Fenton process. More than 40 organic compounds were detected and identified as benzene (0.09?±?0.07 mg?L^-1), trichlorophenol (TCP) (0.18?±?0.12 mg?L^-1), phthalate esters (Di-n-butyl phthalate (DBP), Butyl benzyl phthalate (BBP), Di(2-ethylhexyl) phthalate (DEHP)) (DBP: 0.47?±?0.01 mg?L^-1; BBP: 0.36?±?0.02 mg?L^-1; DEHP: 0.18?±?0.01 mg?L^-1), among others. Toluene, pentachlorophenol, dimethyl phthalate, diethyl phthalate, and Di-n-octyl phthalate were never detected in any of the samples. After the photo-Fenton treatment process, TCP decreased to levels below its detection limit, benzene concentration increased approximately three times, and DBP concentration decreased about 77 % comparatively to the raw leachate sample. The solar photo-Fenton process was considered to be very efficient for the treatment of sanitary landfill leachates, leading to the complete elimination of 24 of the detected micropollutants to levels below their respective detection limits and low to significant abatement of seven other organic compounds, thus resulting in an increase of the leachate biodegradability.