Effects of stand type of artificial forests on soil microbial functional diversity.

We explored the changes of soil microbial biodiversity in response to forest ecological restoration. Soil samples were collected from the close-to nature managed Chinese fir plantation (CF), Moso bamboo plantation (MB), and natural secondary forest (NF). Soil microbial community diversity was analyzed by Biolog-Eco micro-plate technique. The results showed that plant diversity was significantly different among the three stands. Plant diversity of NF was significantly higher than MB and CF, and MB was higher than CF. Soil pH and bulk density showed a great difference, while there was no difference of other soil physiochemical properties among the three stands. Avera-ge well color development (AWCD) of soil in various stands followed the order of NF＞MB＞CF, consistent with the changes of utilization of six types of carbon sources. Shannon index of NF was the highest, and the index of MB was significantly higher than that of CF. Soil physical and chemical properties in different stands were not significantly different, except soil pH and bulk density. The Shannon diversity index (H), Shannon species richness index (S), Simpson dominance index (D) and McIntosh index (U) were the highest in NF, second in MB, and the lowest in CF. Results from principal component analysis (PCA) showed that two factors from 31 carbon sources could explain 60.0% and 12.4% of the variation and that carboxylic acids, carbohydrates and its derivatives, amino acids were the main carbon sources of the two principal component factors. Correlation analysis indicated that plant species richness and Shannon diversity indexes, soil bulk density were significantly correlated to soil microbial community diversity. The microbial community of NF was more efficient in carbon utilization than that in MB and CF, while that in MB was more efficient than that of CF. Based on plant diversity and soil microbial carbon utilization, MB is much better than CF in the artificial forest restoration and improvement in South China.

Characterization of metal removal of immobilized Bacillus strain CR-7 biomass from aqueous solutions.

Bacillus strain CR-7 of multiple metal and antibiotic resistances was isolated. Its metal adsorption under different pretreatments and immobilizations from aqueous solution was characterized. Pretreatment with NaOH (0.1 mol L(-1)) significantly improved Cu(2+) adsorption capacity of the bacterial biomass. Sodium alginate (2%) was the ideal immobilization matrix. The immobilized and pretreated biomass had an obvious "orderliness", following the order of Cu(2+)>Zn(2+) in the solution containing these two metals, and following the order of Pb(2+)>Al(3+)>Cr(6+)>Cu(2+)>Fe(3+)>Zn(2+) = Ni(2+)>Cd(2+) = Co(2+)>Mn(2+) in the solution containing these 10 metals. ΔH° and ΔS° of Cu(2+) adsorption were +7.68 J/mol and +16.628 J/mol K, respectively. The infrared peak of -N-H shifted greatly after Cu(2+) adsorption. After adsorption treatment, some molecular groups disappeared in un-immobilized biomass but were still present in the immobilized biomass. Cu(2+) adsorption fit both Langmuir and Freundlich isotherm models. It was concluded (1) that the Cu(2+) adsorption process was endothermic, (2) that -N-H is a most important Cu(2+)-binding group, (3) that immobilization prevents loss or damage of the Cu(2+)-binding molecular groups, and (4) that Cu(2+) adsorption of pretreated and immobilized biomass is homogeneous.

Characterization of metal removal by os sepiae of Sepiella maindroni Rochebrune from aqueous solutions.

To develop low cost metal adsorbents with less secondary pollution, metal adsorption from the aqueous solutions by the raw os sepiae (ROS) and alkali (NaOH)-pretreated OS (APOS) of the cuttlefish (Sepiella maindroni Rochebrune) was characterized. The capacities of adsorption of ROS and APOS were estimated to be 299.26 mg Cu g(-1) and 299.58 mg Cu g(-1), respectively. Metal adsorption by OS was significantly improved by appropriately increasing initial pH in the solution but hardly affected by temperature change within a wide range of 15-45 degrees C. Cu adsorption of both ROS and APOS was well described neither by Langmuir model nor by Freundlich model. Metal adsorption by OS fell in the order of Fe > Cu approximately = Cd > Zn in the solution with mixed metals, but followed the sequence of Cd > Cu > Fe approximately = Zn in the solutions respectively, with a single metal of Fe, Cu, Cd and Zn. The changes in Ca amounts in OS and solutions in adsorption strongly correlated with removal efficiencies of the metals. Obvious shifts of stretching bands of numbers of groups in OS after and before adsorption and the pretreatment occurred. It was concluded: (1) that metal adsorption by OS involves ion exchange, which occurred mainly between Ca rather than K and Na that OS itself contains and metals that were added in the solution, (2) that metal adsorption-promoting effects by NaOH pretreatment likely involve deprotonation of surface groups in OS, exposure of more functional groups, and increase in specific surface areas and (3) that related mechanisms for adsorption also likely include surface complexation, electrostatic adsorption and even micro-deposition. The results also indicated that OS is a very promising absorbent for metal removal from electroplating wastewater.