Advanced Materials Research Vols. 518-523

Abstract: Blood clam, Tegillarca granosa, facing increasing danger of heavy metal contamination. In order to investigate the toxicological effect of copper (Cu), zinc (Zn), lead (Pb), and cadmium (Cd) on T. granosa, histopathological alternations were investigated in present study. Based on histopathological observation, Cu, Pb and Cd showed different degrees of damages to gills range from gill degeneration, gill fusion to interlamellar space and cilia reduction. In general, the more toxic the more severe damages to gills were observed. Massive oocytes degeneration in female gonad, muscle fiber degeneration and increased gap between muscle fibers in foot were found in Cd-exposure-treated T. granosa. Zn exposure induced an increase of epidermis wrinkles and a reduction of inner gaps. The results reveal different toxic mechanisms of tested heavy metals on T. granosa.

Abstract: The joint effects of Cd and Chlorimuron-ethyl(CE) on Cd accumulation in wheat shoot/root and SPT coefficient of Cd was carried out. Cd concentration in shoot and root increased with increasing soil Cd, but Cd concentration in shoot/root was lower than the same treatment when CE was added, and negative relationship between Cd concentration in shoot (root) and concentration of CE were significant (p<0.05 or p<0.01). There was antagonistic effect of Cd and low CE on Cd accumulation in wheat tissues. Cd concentration in shoot decreased during the period of growth, but the concentration of Cd in root increased from the elongation stage to the florescence, and then decreased from the florescence to mature stage when the concentration of soil Cd was less than 100 mg kg-1, and it decreased when the concentration of soil Cd was 100 mg kg-1. The SPT values of different growth periods decreased during the period of growth.

Abstract: Microwave-assisted extraction (MAE) was used to extract chlorophylls from filter mud. Ethanol was used as the solvent. The optimal conditions for the MAE of chlorophylls were concluded from the study as the irradiation time, 50 s, the ratio of liquid to solid, 8:1 (mL/g), the extraction temperature, 40 °C, and the extraction time, 60 min. Compared with conventional extraction, the MAE of chlorophylls from the filter mud was more effective. The extraction time for MAE was 60 min with 0.277 mg/g chlorophyll yield, while conventional extraction needed 240 min with only about 0.259 mg/g chlorophyll yield. The Ultraviolet Absorption Spectra of the extracted chlorophylls showed that there was a strong absorption peak at about 663 nm. C=N, Mg-N and C-N was not seen existed from the infrared spectroscopy probably because that the mixed extracts were not purified and the chlorophyll content was less.

Abstract: Photolysis is expected to be a major degradation process for pollutants in surface water. This paper studied the photodegradation of metribuzin, a widely used herbicide, in aqueous solution under simulated solar light irradiation. Photolysis of metribuzin was enhanced by the higher light intensity, and the major products were deaminometribuzin and nitrite ions. Metribuzin degradation was inhibited in the absence of oxygen and at higher pH value. In addition, iron in water promoted the degradation of metribuzin, while dissolved organic matter lowered the degradation rate. This investigation is helpful for better understanding the transformation and the potential ecological risk of metribuzin in natural water.

Abstract: Based on DPBs (Denitrifying Phosphorus-removing Bacteria) obtained from a lab-scale SBR, a quinone profile system had been established to analyze quinones in sludge samples. There existed a positive correlation between the contents of UQ-8 extracted from the sludge samples and the denitrifying and phosphorus removal efficiency of the treating system. With quinone profiles taken as a new important index, it was evidently feasible to determine the removal effect.

Abstract: According to the primary study on the As contamination in soil and crops including potato and pea in tin tailings in Gejiu area, Yunnan Province, it has been found that concentrations of As in rhizosphere far exceed Chinese National Grade Ⅲ standard of soil environmental quality of China (GB 15618-1995). It also has been found that the Ferns were living in the tin tailings suffered from the contamination of heavy metals. Compared with the limit of national criteria for food sanitation in China, the concentrations of As in edible parts of ferns are 90 times. Therefore, the remediation of soil based on geochemical distribution characteristics of heavy metal in the tailings is demanded. And avoiding crops-planting in the tailings to reduce the diffusion of heavy metal contamination in food chain of mining area is necessary.

Abstract: Bioflocculant MBF7 was produced by a novel bioflocculant-producing microorganism HHE-P7. In order to reduce the bioflocculant producing cost, culture experiments were conducted. The effects of medium components including carbon and nitrogen sources as well as culture conditions such as pH of molasses diluents, cultivating temperature, inoculum size were investigated. The results showed when the molasses waste was diluted at COD concentration of 2000 mg/L, the optimal culture conditions for MBF7 production by HHE-P7 were inoculum size 1% (v/v), initial pH 5, cultivating temperature 25°C at the rotation speed 150 r/min. Under such conditions, MBF7 had a flocculating activity of 83% for 5 g/L kaolin clay suspension. About 3.19 g crude bioflocculant could be recovered from 1.0 L of molasses fermentation broth.

Abstract: Proteomics responses and adaptations of Camptotheca acuminata seedlings to drought conditions stimulated by treatment with PEG8000 simulation were investigated. We determined the drought responses of seedlings after 30min, 3 h, and 5 h of treatment with15% PEG8000 . The following 2-DE and PMF identification analysis showed that there are many kinds of proteins involved in the regulation of plants responses to environmental drought. Heat shock protein (HSP) and Late embryo abundant protein (LEA) were discovered to take part in the response of C. acuminata to drought environment. Rubisco LSU was found to help C. acuminata to adapt this arid environment in the way of degradation.

Abstract: Biodegradation of decabrominated diphenyl ether (BDE-209) in soil by white rot fungi under various experimental conditions was investigated in this study. It was found that BDE-209 in soil could be rapidly and efficiently degraded by white rot fungi, and the biodegradation fits the pseudo-first-order kinetics during a 15-day incubation period. The residues of BDE-209 in soil decreased with the increase of amount of white rot fungi addition. It can be seen from the results that, white rot fungi have good ability on degradation with one-step or two-step addition method. In native soil, the degradation of BDE-209 reached 52.65%, which was higher than that in sterilized soil. About 37.76-53.74% of BDE-209 was degraded in different soil types after 15 days. In addition, it was confirmed in this study that the presence of Cu²⁺, Cd²⁺ could enhance the remediation of BDE-209 contaminated soil, and the residues decreased by 69.20% and 54.65% for Cu²⁺ and Cd²⁺ treatment, respectively. However, the superior ability of white rot fungi to degrade BDE-209 was not obvious at low pollution level (≤0.5 mg kg^-1).

Abstract: In sequencing batch reactor aerobic granular sludge was cultivated, and the influence of influent C/N ratio to aerobic granular sludge was studied. The results showed that the granulation and the settling ability of the sludge were poor in high C/N, however, low C/N was beneficial to the accumulation of microorganism in reactor and MLSS could reach to as high as 8740 mg/L. Lower C/N ratio would lead to increase of particle size and disintegrate of loose structure and overgrowth on filamentous microbe, these were disadvantage of the stability of the system. It was not obvious that influent C/N ratio affected on the organic removal. The COD removal maintained at 87% after the preliminary form particles were formed in reactor. When C/N ratio was 100:15~100:35, the phosphorus removal efficiency was good. If C/N ratio was too high or too low, the formation of sludge granulation would be affected in the process. The influence of C/N ratio to ammonia nitrogen removal efficiency was obvious. While C/N ratio was 100:10, granular sludge had good simultaneous nitrification and denitrification performance, and the average removal of ammonia nitrogen attained to 91%. But low C/N ratio was able to inhibit the activity of nitrifying bacteria and denitrifying bacteria. At that time, ammonia nitrogen removal rate declined sharply in the system.