HCHs and DDTs in sediment-dwelling animals from the Yangtze Estuary, China

HCHs and DDTs in sediment-dwelling animals including mollusks and crabs from the Yangtze Estuary were determined by GC-ECD. Levels of t-HCH were in the range of 1.2-5.5 ng g(-1) and averaged 3.5 ng g(-1) in mollusks, while t-DDT concentrations ranged from 26.0 to 68.8 ng g(-1), with a mean of 34.5 ng g(-1). In crabs t-HCH concentrations varied from 2.0 to 25.7 ng g(-1) and averaged 13.8 ng g(-1), whereas the concentrations of t-DDT were in the range of 1.5-24.8 ng g(-1) with a mean value of 5.9 ng g(-1). The HCHs and DDTs levels depend on geographical position and sources, showing the high levels at fresh water area in the estuary, such as XP, CM and LHK sites, and lower at brackish water area, such as FX site, and little difference between species. Results also indicate there was no significant relationship between t-HCH (t-DDT) concentrations and lipid contents both in mollusks and crabs because of non-equilibrium state under a specific estuarine dynamics; smaller individuals accumulated more HCHs and DDTs than larger individuals of mollusks at LHK site, showing different uptake rate for these pesticides; moreover, HCHs and DDTs levels were lower in female crab bodies than male crab bodies suggesting that the release of spawning. BSAFs (Biota- Sediment Accumulation Factors) from sediment-dwelling animals for HCHs and DDTs show a significant "one high with two low" and "one low with two high" effect in the Yangtze Estuary.     

Degradation of di-butyl-phthalate by soil bacteria

Twelve Gram-positive phthalate ester degraders were isolated from soil. Using Biolog GP2 plates, eight of them were identified as belonging to the Corynebacterium-Mycobacterium-Nocardia group, while the remaining four were unidentifiable. When cultured in the presence of di-butyl-phthalate (DBP) in basal salts solution, five of these isolates accomplished more than 90% of DBP degradation within 48 h (fast group), three were placed in the medium group, and the remaining four were placed in the slow group which caused less than 30% of DBP degradation within the same period of time. A 420 bp DNA fragment was amplified from six isolates and none of them fell within the slow group. When compared with the large subunit of phthalate dioxygenase gene (phtA) of Arthrobacter keyseri, 83% and 91% similarities were evident in the nucleotide and amino acid sequences, respectively. However, no correlation between cell surface hydrophobicity and phthalate degradation ability was evident. Six surfactants (Brij 30, Brij 35, Tergitoltype NP-10, Triton N-101, Triton X-100 and SDS) were tested for their abilities to increase degradation rate. When added at the critical micellar concentration (CMC), they all displayed strong growth inhibition against the three bacteria tested, with Brij 30 been the least toxic to isolates G2 and G11, and Brij 35 had the least inhibitory effect for G1. When half the CMC of Brij 30 was incorporated into the basal salts, the inhibitory effect on DBP degradation remained. Soil helped to minimize surfactant toxicity of surfactant and increase the degradation potential of some of the test bacteria. When DBP-amended soil had been aged for three months, decreases in bioavailability were observed but the effect varied tremendously between different organisms. For isolates G1, G2, G5, G7 and G17 the aging effects were almost non-exist. The present study indicates that selection of a suitable degrader may minimize the undesired effect of aging on bioremediation process.     

Study of transportation and distribution of PCBs using an ecologically simulated growth chamber

This study was designed to investigate the transportation, distribution, and bioaccumulation of PCBs in various environmental media and compartments using an ecologically simulated growth chamber. Spatial and temporal trends of PCBs in the growth chamber were discussed. The release of PCB congeners in soil was affected by the amount of rainfall with the transporting direction moving away from PCBs contaminated point. Two pathways of PCBs accumulation in plants were the uptake of roots and the deposition on shoots/leaves. There were 29 PCB congeners been found in the lalang grass. Higher concentrations of lower chlorinated PCBs were identified than higher chlorinated PCBs because of relatively higher vapor pressure for lower chlorinated congeners. After 10months of monitoring, PCBs were detected in water samples which were contributed by the release of PCBs from leached soil. Analysis of sediment showed that the percentages of low- and mid-chlorinated biphenyls were decreased 1% and 13%, respectively compared to the increase (14%) of high-chlorinated biphenyls. The increase of high-chlorinated PCBs was possibly caused by their low hydrophilicity which had resulted higher adsorption rate in sediment. All of five species of fish had been found significant amount of PCBs accumulation ( summation operatorPCBs: 21.7-102.1 microg/g-lipid). The concentrations of PCBs in fish were varied significantly among species. The range of bioaccumulation factors (BAFs) among different species of fish could be as much as 5 times depending on the consumption habits of fish. The mass balance of PCBs distribution in the growth chamber was also discussed.     

High average daily intake of PCDD/Fs and serum levels in residents living near a deserted factory producing pentachlorophenol (PCP) in Taiwan: influence of contaminated fish consumption

An abandoned pentachlorophenol plant and nearby area in southern Taiwan was heavily contaminated by dioxins, impurities formed in the PCP production process. The investigation showed that the average serum PCDD/Fs of residents living nearby area (62.5 pg WHO-TEQ/g lipid) was higher than those living in the non-polluted area (22.5 and 18.2 pg WHO-TEQ/g lipid) (P<0.05). In biota samples, average PCDD/F of milkfish in sea reservoir (28.3 pg WHO-TEQ/g) was higher than those in the nearby fish farm (0.15 pg WHO-TEQ/g), and Tilapia and shrimp showed the similar trend. The average daily PCDD/Fs intake of 38% participants was higher than 4 pg WHO-TEQ/kg/day suggested by the world health organization. Serum PCDD/F was positively associated with average daily intake (ADI) after adjustment for age, sex, BMI, and smoking status. In addition, a prospective cohort study is suggested to determine the long-term health effects on the people living near factory.     

Growth and nutritive quality of Poa pratensis as influenced by ozone and competition

Interspecific plant competition has been hypothesized to alter effects of early-season ozone (O3) stress. A phytometer-based approach was utilized to investigate O3 effects on growth and nutritive quality of Poa pratensis grown in monoculture and in mixed cultures with four competitor-plant species (Anthoxanthum odoratum, Achillea millefolium, Rumex acetosa and Veronica chamaedrys). Mesocosms were exposed during April/May 2000-2002 to charcoal-filtered air+25 ppb O3 (control) or non-filtered air+50 ppb O3 (elevated O3). Biomass production was not affected by O3, but foliar injury symptoms were observed in May 2002. Early-season O3 exposure decreased relative food value of P. pratensis by an average of 8%, which is sufficient to have nutritional implications for its utilization by herbivores. However, forage quality response to O3 was not changed by interspecific competition. Lack of injury and nutritive quality response in P. pratensis harvested in September may reflect recovery from early-season O3 exposure.     

Enhanced photocatalysis of pentachlorophenol by metal-modified titanium (IV) oxide

The effects of four metals (Ag, Au, Pt, and Cu) doped on TiO2 on the photocatalysis of pentachlorophenol (PCP) were investigated. The results of this study indicated that all four metals-doped TiO2 catalysts were able to enhance the efficiency of PCP photocatalysis with an optimum metallic content of 0.1 wt%. For the metal-doped TiO2 samples (Au, Pt, and Cu), the patterns of light absorption were significantly extended toward visible light spectra in the wavelengths between 400 and 800 nm. The photocatalysis of PCP was pH dependent with the maximum degradation rate achieved in the solution at pH 3. The formation of chloride ion corresponded with the concentration of PCP degraded which confirmed that dechlorination was the major pathway of PCP photocatalysis. The overall toxicities of PCP samples were reduced with the extension of light exposure using the microtox test. The results of PCP photocatalysis are also discussed based on the characteristics of metal/TiO2 including X-ray differential (XRD) patterns, Brunquer Emmett Teller (BET) specific area analysis, and Ultra Violet (UV)-Vis absorption spectra.     

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.     

Particle generation by ultraviolet-laser ablation during surface decontamination

A novel photonic decontamination method was developed for removal of pollutants from material surfaces. Such a method relies on the ability of a high-energy laser beam to ablate materials from a contaminated surface layer, thus producing airborne particles. In this paper, the authors presented the results obtained using a scanning mobility particle sizer (SMPS) system and an aerosol particle sizer (APS). Particles generated by laser ablation from the surfaces of cement, chromium-embedded cement, and alumina were experimentally investigated. Broad particle distributions from nanometer to micrometer in size were measured. For stainless steel, virtually no particle > 500 nm in aerodynamic size was detected. The generated particle number concentrations of all three of the materials were increased as the 266-nm laser fluence (millijoules per square centimeter) increased. Among the three materials tested, cement was found to be the most favorable for particle removal, alumina next, and stainless steel the least. Chromium (dropped in cement) showed almost no effects on particle production. For all of the materials tested except for stainless steel, bimodal size distributions were observed; a smaller mode peaked at approximately 50-70 nm was detected by SMPS and a larger mode (peaked at approximately 0.70-0.85 microm) by APS. Based on transmission electron microscopy observations, the authors concluded that particles in the range of 50-70 nm were aggregates of primary particles, and those of size larger than a few hundred nanometers were produced by different mechanisms, for example, massive object ejection from the material surfaces.     

Pozzolanic reactivity of the synthetic slag from municipal solid waste incinerator cyclone ash and scrubber ash

This study investigates the pozzolanic reactions and compressive strength of the blended cement manufactured using synthetic slag obtained from municipal solid waste incinerator (MSWI) cyclone ash and scrubber ash as partial replacement of portland cement. The synthetic slag was made by co-melting the MSWI scrubber ash and cyclone ash mixtures at 1400 degrees C for 30 min. Following pulverization, the different types of slag were blended with cement as cement replacement at ratios ranging from 10 to 40 wt %. The synthetic slag thus obtained was quantified, and the characteristics of the slag-blended cement pastes were examined. These characteristics included the pozzolanic activity, compressive strength, hydration activity, crystal phases, species, and microstructure at various ages. The 90-day compressive strength developed by slag-blended cement pastes with 10 and 20 wt % of the cement replaced by the synthetic slag outperformed ordinary portland cement by 1-7 MPa. X-ray diffraction species analyses indicated that the hydrates in the slag-blended cement pastes were mainly portlandite, the calcium silicate hydrate gels, and calcium aluminate hydrate salts, similar to those found in ordinary portland cement paste. Differential thermal and thermogravimetric analysis also indicated that the slag reacted with portlandite to form calcium silicate hydrate gels.