Observation of chemical components of PM2.5 and secondary inorganic aerosol formation during haze and sandy haze days in Zhengzhou, China

Mineral dust particles play an important role in the formation of secondary inorganic aerosols, which largely contribute to haze pollution in China.During this study, a haze episode(haze days) and a typical haze process mixed with sandstorm(sandy haze days)were observed in Zhengzhou with a series of high-time-resolution monitoring instruments from November 22 to December 8, 2018.Concentrations of PM_(10) and crustal elements clearly increased in the sandy haze days.Concentrations of gaseous pollutants, metallic elements emitted from anthropogenic sources, nitrate, and ammonium during sandy haze days were slightly lower than those during the haze days but still obviously higher than those during the non-haze days.The sulfate concentrations, the sulfate fractions in PM_(2.5),and the sulfur oxidation ratios significantly increased in the sandy haze days.Heterogeneous reactions dominated the conversion of SO_2 during the haze and sandy haze days.Enhanced SO_2 conversion during the sandy haze days may be attributed to the high concentrations of transition metal ions from the sandstorm when the values of relative humidity(RH) were in 30%–70%, and high O_3 at certain time points.Gas-phase NO_2 oxidation reactions were the main pathways for nitrate formation.In the sandy haze days,higher nitrogen oxidation ratio(NOR) at daytime may be associated with higher RH and lower temperature than those in the haze days, which facilitate the gas-to-particle partitioning of nitrate; higher NOR values at night may be attributed to the higher O_3 concentrations, which promoted the formation of N_2O_5.     

Characteristics of secondary inorganic aerosol and sulfate species in size-fractionated aerosol particles in Shanghai

Sulfate, nitrate and ammonium(SNA) are the dominant species in secondary inorganic aerosol, and are considered an important factor in regional haze formation. Size-fractionated aerosol particles for a whole year were collected to study the size distribution of SNA as well as their chemical species in Shanghai. SNA mainly accumulated in fine particles and the highest average ratio of SNA to particulate matter(PM) was observed to be 47% in the fine size fraction(0.49–0.95 μm). Higher sulfur oxidation ratio and nitrogen oxidation ratio values were observed in PM of fine size less than 0.95 μm. Ion balance calculations indicated that more secondary sulfate and nitrate would be generated in PM of fine size(0.49–0.95 μm). Sulfur K-edge X-ray absorption near-edge structure(XANES) spectra of typical samples were analyzed. Results revealed that sulfur mainly existed as sulfate with a proportion(atomic basis) more than 73% in all size of PM and even higher at 90% in fine particles. Sulfate mainly existed as(NH4)2SO4 and gypsum in PM of Shanghai. Compared to non-haze days, a dramatic increase of(NH4)2SO4 content was found in fine particles on haze days only, which suggested the promoting impact of(NH4)2SO4 on haze formation. According to the result of air mass backward trajectory analysis, more(NH4)2SO4 would be generated during the periods of air mass stagnation. Based on XANES, analysis of sulfate species in size-fractionated aerosol particles can be an effective way to evaluate the impact of sulfate aerosols on regional haze formation.     

Chemical characteristics of PM2:5 during a typical haze episode in Guangzhou

The chemical characteristics (water-soluble ions and carbonaceous species) of PM2:5 in Guangzhou were measured during a typical haze episode. Most of the chemical species in PM2:5 showed significant di erence between normal and haze days. The highest contributors to PM2:5 were organic carbon (OC), nitrate, and sulfate in haze days and were OC, sulfate, and elemental carbon (EC) in normal days. The concentrations of secondary species such as, NO3??, SO4 2??, and NH4 + in haze days were 6.5, 3.9, and 5.3 times higher than those in normal days, respectively, while primary species (EC, Ca2+, K+) show similar increase from normal to haze days by a factor about 2.2–2.4. OC/EC ratio ranged from 2.8 to 6.2 with an average of 4.7 and the estimation on a minimum OC/EC ratio showed that SOC (secondary organic carbon) accounted more than 36.6% for the total organic carbon in haze days. The significantly increase in the secondary species (SOC, NO3??, SO4 2??, and NH4 +), especially in NO3??, caused the worst air quality in this region. Simultaneously, the result illustrated that the serious air pollution in haze episodes was strongly correlated with the meteorological conditions. During the sampling periods, air pollution and visibility had a good relationship with the air mass transport distance; the shorter air masses transport distance, the worse air quality and visibility in Guangzhou, indicating the strong domination of local sources contributing to haze formation. High concentration of the secondary aerosol in haze episodes was likely due to the higher oxidation rates of sulfur and nitrogen species.     

Typical atmospheric haze during crop harvest season in northeastern China: A case in the Changchun region

This study presents the mass concentrations of PM_(2.5),O_3,SO_2 and NOxat one urban,one suburban and two rural locations in the Changchun region from September 25 to October 272013. Major chemical components of PM_(2.5)at the four sites were daily sampled and analyzed. Most of daily concentrations of SO_2(7–82 μg/m~3),O_3(27–171 μg/m~3) and NOx(14–213 μg/m~3) were below the limits of the National Ambient Air Quality Standard(NAAQS)in China. However,PM_(2.5)concentrations(143–168 μg/m~3) were 2-fold higher than NAAQS.Higher PM_(2.5)concentrations(~ 150 μg/m~3) were measured during the pre-harvest and harvest at the urban site,while PM_(2.5)concentrations significantly increased from 250 to400 μg m~(-3) at suburban and rural sites with widespread biomass burning. At all sites,PM_(2.5)components were dominated by organic carbon(OC) and followed by soluble component sulfate(SO_4~(2-)),ammonium(NH_4~+) and nitrate(NO_3~-). Compared with rural sites,urban site had a higher mineral contribution and lower potassium(K~+and K) contribution to PM_(2.5).Severe atmospheric haze events that occurred from October 21 to 23 were attributed to strong source emissions(e.g.,biomass burning) and unfavorable air diffusion conditions.Furthermore,coal burning originating from winter heating supply beginning on October 18 increased the atmospheric pollutant emissions. For entire crop harvest period,the Positive Matrix Factorization(PMF) analysis indicated five important emission contributors in the Changchun region,as follows: secondary aerosol(39%),biomass burning(20%),supply heating(18%),soil/road dust(14%) and traffic(9%).     

Characteristics of the water-soluble components of aerosol particles in Hefei, China

Size-classified daily aerosol mass concentrations and concentrations of water-soluble inorganic ions were measured in Hefei,China,in four representative months between September 2012 and August 2013.An annual average mass concentration of 169.09μg/m~3 for total suspended particulate(TSP)was measured using an Andersen Mark-II cascade impactor.The seasonal average mass concentration was highest in winter(234.73μg/m~3)and lowest in summer(91.71μg/m~3).Water-soluble ions accounted for 59.49%,32.90%,48.62%and 37.08%of the aerosol mass concentration in winter,spring,summer,and fall,respectively,which indicated that ionic species were the primary constituents of the atmospheric aerosols.The four most abundant ions were NO_3~-,SO_4~(2-),Ca~(2+) and NH_4~+.With the exception of Ca~(2+),the mass concentrations of water-soluble ions were in an intermediate range compared with the levels for other Chinese cities.Sulfate,nitrate,and ammonium were the dominant fine-particle species,which were bimodally distributed in spring,summer and fall;however,the size distribution became unimodal in winter,with a peak at 1.1–2.1μm.The Ca~(2+) peak occurred at approximately 4.7–5.8μm in all seasons.The cation to anion ratio was close to 1.4,which suggested that the aerosol particles were alkalescent in Hefei.The average NO_3~-/SO_4~(2-)mass ratio was 1.10 in Hefei,which indicated that mobile source emissions were predominant.Significant positive correlation coefficients between the concentrations of NH_4~+ and SO_4~(2-),NH_4~+ and NO_3~-,SO_4~(2-)and NO_3~-,and Mg~(2+) and Ca~(2+) were also indicated,suggesting that aerosol particles may be present as(NH_4)_2SO_4,NH_4HSO_4,and NH_4NO_3.     

Size-resolved aerosol water-soluble ions at a regional background station of Beijing, Tianjin, and Hebei, North China

The characteristics of water-soluble ions in size-resolved particulate matter were investigated usingion chromatography at Shangdianzi,a regional background station of Beijing,Tianjin,and Hebei.Seasonal total concentrations of ions(Na~+,Mg~(2+),K~+,Ca~(2+),NH_4~+,Cl~-,SO_4~(2-) and NO_3~-) were75.5±52.9 μg/m~3 in spring,26.5±12.3μg/m~3 in summer,22.7±20.4μg/m~3 in autumn,and31.1±23.9 μg/m~3 in winter,respectively.The secondary ions(NO_3~-,SO_4~(2-) and NH_4~+),mainly associated with fine particles,accounted for 84.2%in spring,82.1%in summer,81.5%in autumn and 76.3%in winter of all ions.Strong correlations were found between NH_4~+ and SO_4~(2-)(r=0.95,p0.01) as well as NH_4~+ and NO_3~-(r=0.90,p0.01) in fine particles;while in coarse particles,correlations between Mg~(2+) and NO_3~-(r=0.80,p0.01),and Ca~(2+) and NO_3~-(r=0.85,p0.01) were found.The concentrations of Na~+,K~+,Mg~(2+),Ca~(2+),NH_4~+,Cl~-,NO_3~-,and SO_4~(2-) were 2.02,0.81,0.36,1.65,9.58,4.01,18.9,and 18.4 μg/m~3 in particulate matter from southeast-derived air masses,which were typically 1.58-3.37 times higher than in northwest trajectories.Thus,concentrations of water-soluble ions at this background station were heavily influenced by regional transport of serious pollution derived from biomass burning,coal combustion,industrial and vehicle exhaust emissions from Beijing,Tianjin,and Hebei.     

Concentrations and chemical compositions of PM10 during hazy and non-hazy days in Beijing

In order to study the concentrations of major components,characteristics and comparison in hazy and non-hazy days of PM_(10) in Beijing,aerosol samples were collected at urban site in Beijing from December 29,2014 to January 22,2015.Heavy metals like Zn,Pb,Mn,Cu,As,V,Cr and Cd were deeply studied considering their toxic effects on human being;nine water-soluble inorganic ions(SO_4~(2-),NO_3~-,NH_4~+,Na~+,K~+,Cl~-,Ca~(2+) and Mg~(2+)) and carbon fractions(OC and EC) were also analyzed.The concentrations of heavy metals were 1.03–1.98 times higher in hazy days than those in non-hazy days,mainly due to biomass burning and coal burning.The trends in total heavy metals concentrations were basically consistent with the trends in PM concentrations except for two obvious periods(12.29–12.30;1.14–1.15);but when air masses accumulated locally or around Beijing,trends in PM concentrations and heavy metals were opposite.The proportion for NO_3~-/SO_4~(2-) indicated that mobile sources such as automobiles were important reasons for haze in Beijing.Correlation between OC and EC during non-hazy days was strong(R~2= 0.95) but it was low(R~2= 0.67) during hazy days,and large variations for OC/EC values occurred in hazy days.The calculated mass concentration of SOC is 2.58 μg/m~3,which only accounted for 10.1% of the OC concentration.When air masses from the far north-west,they decreased PM concentration in Beijing and they were relatively clean;however,those from the near east,south-east and south of the mainland increased PM concentration and they were dirty.     

Chemical characterization of size-resolved aerosols in four seasons and hazy days in the megacity Beijing of China

Size-resolved aerosol samples were collected by MOUDI in four seasons in 2007 in Beijing. The PM10 and PM1.8mass concentrations were 166.0 ± 120.5 and 91.6 ± 69.7 μg/m~3, respectively,throughout the measurement, with seasonal variation: nearly two times higher in autumn than in summer and spring. Serious fine particle pollution occurred in winter with the PM1.8/PM10 ratio of 0.63, which was higher than other seasons. The size distribution of PM showed obvious seasonal and diurnal variation, with a smaller fine mode peak in spring and in the daytime. OM(organic matter = 1.6 × OC(organic carbon)) and SIA(secondary inorganic aerosol) were major components of fine particles, while OM, SIA and Ca_2+were major components in coarse particles. Moreover, secondary components, mainly SOA(secondary organic aerosol) and SIA,accounted for 46%–96% of each size bin in fine particles, which meant that secondary pollution existed all year. Sulfates and nitrates, primarily in the form of(NH_4)_2SO_4, NH_4NO_3, Ca SO_4, Na_2SO_4 and K_2SO_4, calculated by the model ISORROPIA II, were major components of the solid phase in fine particles. The PM concentration and size distribution were similar in the four seasons on non-haze days, while large differences occurred on haze days, which indicated seasonal variation of PM concentration and size distribution were dominated by haze days. The SIA concentrations and fractions of nearly all size bins were higher on haze days than on non-haze days, which was attributed to heterogeneous aqueous reactions on haze days in the four seasons.     

Chemical characteristics of haze particles in Xi'an during Chinese Spring Festival: Impact of fireworks burning

Fireworks burning releases massive fine particles and gaseous pollutants, significantly deteriorating air quality during Chinese Lunar New Year(LNY) period. To investigate the impact of the fireworks burning on the atmospheric aerosol chemistry, 1-hr time resolution of PM_(2.5) samples in Xi'an during the winter of 2016 including the LNY were collected and detected for inorganic ions, acidity and liquid water content(LWC) of the fine aerosols. PM_(2.5) during the LNY was 167 ± 87 μg/m~3, two times higher than the China National Ambient Air Quality Standard(75 μg/m~3). K~+(28 wt.% of the total ion mass) was the most abundant ion in the LNY period, followed by SO_4~(2-)(25 wt.%) and Cl-(18 wt.%). In contrast, NO_3~-(34 wt.%) was the most abundant species in the haze periods(hourly PM32-2.5 75 μg/m), followed by SO_4(29.2 wt.%) and NH_4~+(16.3 wt.%), while SO_4~(2-)(35 wt.%) was the most abundant species in the clean periods(hourly PM_(2.5) 75 μg/m~3), followed by NO_3~-(23.1 wt.%) and NH_4~+(11 wt.%). Being different from the acidic nature in the non-LNY periods, aerosol in the LNY period presented an alkaline nature with a pH value of 7.8 ± 1.3. LWC during the LNY period showed a robust linear correlation with K_2SO_4 and KCl, suggesting that aerosol hygroscopicity was dominated by inorganic salts derived from fireworks burning. Analysis of correlations between the ratios of NO--3/SO_4~(2-) and NH_4~+/SO_4~(2-) indicated that heterogeneous reaction of HNO_3 with NH_3 was an important formation pathway of particulate nitrate and ammonium during the LNY period.     

An efficient way to enhance the total nitrogen removal efficiency of the Anammox process by S0-based short-cut autotrophic denitrification

In order to reduce the amount of NO_3~-–N generated by the Anammox process, and alleviate the competition between denitrification and Anammox for NO_2~-–N in a single reactor, the preference of S~0 for reacting with coexisting NO_2~-–N and NO_3~-–N in the sulfur autotrophic denitrifying(SADN) process and the coupling effect of short-cut SADN and the Anammox process were studied. The results showed that S~0 preferentially reacted with NO_3~-to produce NO_2~-–N, and then reacted with NO_2~-–N when NO_3~-–N was insufficient, which could effectively alleviate the competition between SADN bacteria(SADNB) and Anammox bacteria(An AOB) for NO_2~-–N. After 170 days of operation, coupling between short-cut S~0-SADN and the Anammox process was first successfully achieved. SADNB converted the NO_3~-–N generated by the Anammox process into NO_2~-–N, which was once again available to An AOB. The total nitrogen removal efficiency eventually stabilized at over 95%, and the effluent NO_3~-–N was controlled within 10 mg/L, when high NH_4~+–N wastewater was treated by the Anammox process. Microbial community analysis further showed that Candidatus Brocadia and Thiobacillus were the functional microorganisms for An AOB and SADNB.     

Toxic effects of acetochlor, methamidophos and their combination on nifH gene in soil

Toxic effects of two agrochemicals on nifH gene in agricultural black soil were investigated using denaturing gradient gel electrophoresis （DGGE） and sequencing approaches in a microcosm experiment. Changes of soil nifH gene diversity and composition were examined following the application of acetochlor, methamidophos and their combination. Acetochlor reduced the nifH gene diversity （both in gene richness and diversity index values） and caused changes in the nifH gene composition. The effects of acetochlor on nifH gene were strengthened as the concentration of acetochlor increased. Cluster analysis of DGGE banding patterns showed that nifH gene composition which had been affected by low concentration of acetochlor （50 mg/kg） recovered firstly. Methamidophos reduced nifH gene richness that except at 4 weeks. The medium concentration of methamidophos （150 mg/kg） caused the most apparent changes in nifH gene diversity at the first week while the high concentration of methamidophos （250 mg/kg） produced prominent effects on nifH gene diversity in the following weeks. Cluster analysis showed that minimal changes of nifH gene composition were found at 1 week and maximal changes at 4 weeks. Toxic effects of acetochlor and methamidophos combination on nifH gene were also apparent. Different nifH genes （bands） responded differently to the impact of agrochemicals： four individual bands were eliminated by the application of the agrochemicals, five bands became predominant by the stimulation of the agrochemicals, and four bands showed strong resistance to the influence of the agrochemicals. Fifteen prominent bands were partially sequenced, yielding 15 different nifH sequences, which were used for phylogenetic reconstructions. All sequences were affiliated with the alpha- and beta-proteobacteria, showing higher similarity to eight different diazotrophic genera.     

Arsenic uptake by arbuscular mycorrhizal maize （Zea mays L.） grown in an arsenic-contaminated soil with added phosphorus

The effects of arbuscular mycorrhizal (AM) fungus (Glomus mosseae) and phosphorus (P) addition (100 mg/kg soil) on arsenic (As) uptake by maize plants (Zea mays L.) from an As-contaminated soil were examined in a glasshouse experiment.Non-mycorrhizal and zero-P addition controls were included.Plant biomass and concentrations and uptake of As,P,and other nutrients,AM colonization,root lengths,and hyphal length densities were determined.The results indicated that addition of P significantly inhibited root colonization and development of extraradical mycelium.Root length and dry weight both increased markedly with mycorrhizal colonization under the zero-P treatments,but shoot and root biomass of AM plants was depressed by P application.AM fungal inoculation decreased shoot As concentrations when no P was added,and shoot and root As concentrations of AM plants increased 2.6 and 1.4 times with P addition,respectively.Shoot and root uptake of P,Mn,Cu,and Zn increased,but shoot Fe uptake decreased by 44.6%,with inoculation, when P was added.P addition reduced shoot P,Fe,Mn,Cu,and Zn uptake of AM plants,but increased root Fe and Mn uptake of the nonmycorrhizal ones.AM colonization therefore appeared to enhance plant tolerance to As in low P soil,and have some potential for the phytostabilization of As-contaminated soil,however,P application may introduce additional environmental risk by increasing soil As mobility.     

Potential of plant polyphenol oxidases in the decolorization and removal of textile and non-textile dyes

In this study an effort has been made to use plant polyphenol oxidases; potato （Solanum tuberosum） and brinjal （Solanum melongena）, for the treatment of various important dyes used in textile and other industries. The ammonium sulphate fractionated enzyme preparations were used to treat a number of dyes under various experimental conditions. Majority of the treated dyes were maximally decolorized at pH 3.0. Some of the dyes were quickly decolorized whereas others were marginally decolorized. The initial first hour was sufficient for the maximum decolorization of dyes. The rate of decolorization was quite slow on long treatment of dyes. Enhancement in the dye decolorization was noticed on increasing the concentration of enzymes. The complex mixtures of dyes were treated with both preparations of polyphenol oxidases in the buffers of varying pH values. Potato polyphenol oxidase was significantly more effective in decolorizing the dyes to higher extent as compared to the enzyme obtained from brinjal polyphenol oxidase. Decolorization of dyes and their mixtures, followed by the formation of an insoluble precipitate, which could be easily removed simply by centrifugation.     

Removal of heavy metals from sewage sludge by low costing chemical method and recycling in agriculture

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Single and joint effects of pesticides and mercury on soil urease

The influence of two pesticides including chlorimuron-ethyl and furadan and mercury （Hg） on urease activity in 4 soils （meadow burozem and phaeozem） was investigated. The soils were exposed to various concentrations of the two pesticides and Hg individually and simultaneously. Results showed that there was a close relationship between urease activity and organic matter content in soil. Chlorimuron-ethyl and furadan could both activate urease in the 4 soils. The maximum increment of urease activity by chlorimuronethyl was up to 14%-18%. There was almost an equal increase （up to 13%-21%） in the urease activity by furadan. On the contrary, Hg markedly inhibited soil urease activity. A logarithmic equation was used to describe the relationship （P〈0.05） between the concentration of Hg and the activity of soil urease in the 4 tested soils. Semi-effect dose （ED50） values by the stress of Hg based on the inhibition of soil urease in the 4 soils were 88, 5.5, 24 and 20 mg/kg, respectively, according to the calculation of the corresponding equations. The interactive effect of chlorimuron-ethyl or furadan with metal Hg on soil urease was mainly synergic at the highest tested concentrations.     

Isolation and preliminary characterization of a 3-chlorobenzoate degrading bacteria

A study was conducted to compare the diversity of 2-, 3-, and 4-chlorobenzoate degraders in two pristine soils and one contaminated sewage sludge. These samples contained strikingly different populations of mono-chlorobenzoate degraders. Although fewer cultures were isolated in the uncontaminated soils than contaminated one, the ability of microbial populations to mineralize chlorobenzoate was widespread. The 3- and 4-chlorobenzoate degraders were more diverse than the 2-chlorobenzoate degraders. One of the strains isolated from the sewage sludge was obtained. Based on its phenotype, chemotaxonomic properties and 16S rRNA gene, the organism S-7 was classified as Rhodococcus erythropolis. The strain can grow at temperature from 4 to 37℃. It can utilize several （halo）aromatic compounds. Moreover, strain S-7 can grow and use 3-chlorobenzoate as sole carbon source in a temperatures range of 10-30℃ with stoichiometric release of chloride ions. The psychrotolerant ability was significant for bioremediation in low temperature regions. Catechol and chlorocatechol 1,2-dioxygenase activities were present in cell free extracts of the strain, but no （chloro）catechol 2,3- dioxygenase activities was detected. Spectral conversion assays with extracts from R. erythropolis S-7 showed accumulation of a compound with a similar UV spectrum as chloro-cis,cis-muconate from 3-chlorobenzoate. On the basis of these results, we proposed that S-7 degraded 3-chlorobenzoate through the modified ortho-cleave pathway.     

Organochlorine pesticides in soils under different land usage in the Taihu Lake region, China

A field study was conducted in the Taihu Lake region, China in 2004 to reveal the organochlorine pesticide concentrations in soils after the ban of these substances in the year 1983. Thirteen organochlorine pesticides (OCPs) were analyzed in soils from paddy field, tree land and fallow land. Total organochlorine pesticide residues were higher in agricultural soils than in uncultivated fallow land soils. Among all the pesticides, ΣDDX (DDD, DDE and DDT) had the highest concentration for all the soil samples, ranging from 3.10 ng/g to 166.55 ng/g with a mean value of 57.04 ng/g and followed by ΣHCH, ranging from 0.73 ng/g to 60.97 ng/g with a mean value of 24.06 ng/g. Dieldrin, endrin, HCB and α-endosulfan were also found in soils with less than 15 ng/g. Ratios of p,p'-(DDD DDE)/DDT in soils under three land usages were: paddy field ＞ tree land ＞ fallow land, indicating that land usage inlfuenced the degradation of DDT in soils. Ratios of p,p'-(DDD DDE)/DDT ＞1, showing aged residues of DDTs in soils of the Taihu Lake region. The results were discussed with data from a former study that showed very low actual concentrations of HCH and DDT in soils in the Taihu Lake region, but according to the chemical half-lives and their concentrations in soils in 1980s, the concentration of DDT in soils seemed to be underestimated. In any case our data show that the ban on the use of HCH and DDT resulted in a tremendous reduction of these pesticide residues in soils, but there are still high amounts of pesticide residues in soils, which need more remediation processes.     

Sorption of 1-naphthol by plant cuticular fractions

The contribution of aliphatic-rich plant biopolymer to sorption of hydrophobic organic compounds is significantly important because of their preservation and accumulation in the soil environment,but sorption mechanism is still not fully understood.In this study, sorption of 1-naphthol by plant cuticular fractions was examined to better understand the contributions of respective fraction.Toward this end,cuticular materials were isolated from the fruits of tomato by chemical method.The tomato cuticle sheet consisted of waxes (6.5 wt%),cuticular monomer (69.5 wt%),and polysaccharide (24.0 wt%).Isotherms of l-naphthol to the cuticular fractions were nonlinear (N value (0.82-0.90)) at the whole tested concentration ranges.The KodKow ratios for bulk cuticle (TC1),dewaxed cuticle (TC2),cutin (TC4),and desugared cuticle (TC5) were larger than unity,suggested that tomato bulk cuticle and cutin are much powerful solption medium.Sorption capability of cutin (TC4) was 2.4 times higher than the nonsaponifiable fraction (TC3).The 1-naphthol interactions with tomato cuticular materials were governed by both hydrophobic-type interactions and polar (H-bonding) interactions. Removal of the wax and polysaccharide materials from the bulk tomato cuticle caused a significant increase in the sorption ability of the cuticular material.There was a linear negative trend between K_(oc) values and the amount of polysaccharides or fraction's polarities ((N O)/C);while a linear positive relationship between K_(oc) values and the content of cutin monomer (linear R~2=0.993) was observed for present in the cuticular fractions.Predominant sorbent of the hydrophobic organic compounds (HOCs) in the plant cuticular fraction was the cutin monomer,contributing to 91.7% of the total sorption of tomato bulk cuticle.     

Alterations of organ histopathology and metallolhionein mRNA expression in silver barb, Puntius gonionotus during subchronic cadmium exposure

Common silver barb,Puntius gonionotus,exposed to the nominal concentration of 0.06 mg/L Cd for 60 d,were assessed for histopathological alterations(gills,liver and kidney),metal accumulation,and metallothionein(MT)mRNA expression.Fish exhibited pathological symptoms such as hypertrophy and hyperplasia of primary and secondary gill lamellae,vacuolization in hepatocytes,and prominent tubular and glomerular damage in the kidney.In addition,kidney accumulated the highest content of cadmium,more than gills and liver.Expression of MT mRNA was increased in both liver and kidney of treated fish.Hepatic MT levels remained high after fish were removed to Cd-free water.In contrast,MT expression in kidney was peaked after 28 d of treatment and drastically dropped when fish were removed to Cd-free water.The high concentrations of Cd in hepatic tissues indicated an accumulation site or permanent damage on this tissue.     

Seed selections for crystallization of calcium phosphate for phosphorus recovery

Seed induces and promotes the crystallization of calcium phosphate, and acts as carrier of the recovered phosphorus （P）. In order to select suitable seed for P recovery from wastewater, three seeds including Apatite （AP）, Juraperle （JP） and phosphate-modified Juraperle （M-JP） were tested and compared. Batch and fixed-bed column experiments of seeded crystallization of calcium phosphate were undertaken by using synthetic wastewater with 10 mg/L P phosphate. It shows that AP has bad enduring property in the crystallization process, while JP has better performance for multiple uses, and M-JP is a hopeful seed for P recovery by crystallization of calcium phosphate.