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In order to solve environmental problems resulting from ammonia released into the atmosphere, the emission of ammonia contamination from monosodium glutamate (MSG) production was quantitatively observed, and the relationships with relevant influencing factors (ammonium-N, nitrate/nitrite-N and pH) were statistically analyzed. The results indicated that the release of gaseous ammonia from MSG production including the treatment and discharge of wastewater was highly dependent on the technical processes utilised. The flux of ammonia released from the fermentation workshop was highest, up to 8.98 × 10 mg m min, and the flux from the sugar-refining workshop was lowest, only 85.1 mg m min. The release of gaseous ammonia during the whole MSG production was significantly proportional to the concentration of ammonium-N in the discharged solution, and exponentially proportional to the concentrations of nitrate–nitrogen and nitrite-nitrogen in the discharged solution. Although there was no linear relationship between the flux of ammonia released during the whole MSG production and pH values in the discharged solution, pH was significantly related to the flux of ammonia released during the treatment and discharge of wastewater. [ABSTRACT FROM AUTHOR]

This paper demonstrates the Pb2+ adsorption capacity and adsorption rate of Saccharomyces cerevisiae by both static and dynamic testing to verify its feasibility as a heavy metal bio-absorbent in wastewater treatment. The static testing was divided into two parts. First, we tested S. cerevisiae by itself, and then we tested immobilized S. cerevisiae. In static testing of the non-immobilized S. cerevisiae, the Pb2+ adsorption capacity and adsorption rate increased up to 6.52 mg/g and 52.94%, respectively, with time. After immobilization, the Pb2+ adsorption capacity and adsorption rate reached 10 mg/g and 80%, respectively. In dynamic testing, the optimal saturated adsorption capacity of immobilized S. cerevisiae for Pb2+ was 6.64 mg/g. In addition to the static and dynamic testing of adsorption capacity and rate, we used SEM imaging to analyze the mechanics of adsorption, and the images showed that the cell wall played the major roll in Pb2+ adsorption. [ABSTRACT FROM AUTHOR]

In the process of bioremediation in the soil contaminated by different oil concentrations, the changes in the microbial numbers (bacteria and fungi) and the enzyme (catalase (CAT), polyphenol oxidase (PPO) and lipase) activities were evaluated over a 2-year period. The results showed that the microbial numbers after 2-year bioremediation were one to ten times higher than those in the initial. The changes in the bacterial and the fungal populations were different during the bioremediation, and the highest microbial numbers for bacteria and fungi were 5.51 × 109 CFU g−1 dry soil in treatment 3 (10,000 mg kg−1) in the initial and 5.54 × 105 CFU g−1 dry soil in treatment 5 (50,000 mg kg−1) after the 2-year bioremediation period, respectively. The CAT and PPO activities in the contaminated soil decreased with increasing oil concentration, while the lipase activity increased. The activities of CAT and PPO improved after the bioremediation, but lipase activity was on the contrary. The CAT activity was more sensible to the oil than others, and could be alternative to monitor the bioremediation process. [ABSTRACT FROM AUTHOR]

In a microcosm experiment, the amplified ribosomal DNA restriction analysis was adopted to investigate the Pseudomonas community structure in soils applied with different concentrations (0, 50, 150, and 250 mg/kg) of acetochlor, and an in vitro assay was made to examine the antagonistic activity of isolated Pseudomonas strains acting on soil-borne pathogen Rhizoctonia solani. The results showed that acetochlor application changed the community structure of Pseudomonas in aquic brown soil. The diversity of Pseudomonas and the amount of isolated Pseudomonas strains with antagonistic activity decreased with an increasing acetochlor concentration, and the toxic effect of acetochlor reached to a steady level at 150–250 mg/kg. [ABSTRACT FROM AUTHOR]

Application of synthetic chelates such as ethylene diamine tetraacetic acid (EDTA) has been proposed as an alternative technology for phytoextraction of contaminated soils. In a pot experiment, the effects of EDTA application at three growing stages on growth and Cd uptake and accumulation of Solanum nigrum L. were investigated. The results showed that the 0.1 g/kg EDTA treatment was the most effective treatment, in which the concentrations of Cd in stems and leaves increased significantly compared with the control (Cd only), and the accumulation of Cd in shoots increased by 51.6%, 61.1% and 35.9% at the seedling, flowering and mature stages, respectively. Moreover, at the flowering stage, the height, dry shoot biomass and Cd accumulation in the plants reached the maximum, which were 18.9 cm, 1.8 g/plant and 292.8 μg/pot, respectively. However, higher rate of EDTA (0.5 g/kg) could reduce the plant biomass and the total amount of Cd removed. The results indicated that moderate rate of EDTA applied at the flowering stage would be important to enhance phytoremediation efficiency in practice. [ABSTRACT FROM AUTHOR]

Soil pollution by cadmium has been a long standing ecological problem in Zhangshi Irrigation Area, Shenyang, China, as a result of the 30-year practice of irrigation with wastewater containing high levels of heavy metals. To evaluate the adverse impact of cadmium contamination on soil ecosystems, the responses of soil microbiota to both long-term and short-term cadmium stress were studied by molecular microbial community profiling with denaturating gradient gel electrophoresis (DGGE) analysis. Our results show that soil characteristics and nutrient conditions were likely more important than cadmium toxicity in shaping the soil bacterial community structure in the long term. In comparison, soil microbial genetic diversity was shown to be more closely correlated to cadmium levels under short-term cadmium stress, with the highest microbial genetic diversity occurring at mild cadmium stress conditions, which might be attributed to the enrichment of metal-resistant microbial populations through mechanisms of competitive selection and genetic adaptation. In contrast, severe cadmium stress likely presented a condition that fewer microbial populations could survive, thus leading to reduced microbial genetic diversity. [ABSTRACT FROM AUTHOR]

The remediation of diesel fuel contaminated soil over a 2-year period by the plant–microorganism synergy was evaluated. Results indicated that the growth of Astragalus adsurgens was affected significantly, when the diesel fuel concentration was higher than 10 g kg−1 dry soil. After a 2-year period, the removal of diesel fuel was >67%, and about 58–70% removal of aromatic hydrocarbons was obtained in these treatments. The removal of diesel fuel and its components was 13–30% higher than that of plant alone. These results show that an appropriate plant–microorganism synergy may serve as a low-cost, effective remedial technology for diesel-contaminated soil. [ABSTRACT FROM AUTHOR]

This article discusses cadmium and lead speciation in the soil of northeast China as affected by the level of metal loading, aging time and the interaction between the two metals. The concentrations of these heavy metals were analyzed using an atomic absorption spectrophotometer. Sequential extraction was developed for fractions defined as SE (water soluble plus exchangeable); WSA (bound to carbonate or weakly specifically adsorbed); OX (bound to Fe or Mn oxides); OM (bound to organic matter) and RES (residual). According to the authors, good linear relationships were obtained between the soluble exchangeable fraction content of metals in soil and the ionic impulsion. Apparently, for longer aging times there is a movement of cadmium and lead to the weakly specifically absorbed and residual fractions.