石油污染土壤及地下水的生物修复进展

This paper presents a review with 41 references on bioremediation of oil or oil products contaminated soil and groundwater in the past several years．Many aspects are discussed,such as the types of remedied soils,the degraded pollutants,separation and selection of strains for oil degradation,effects of the added nutrition or other substances,and some available techniques of bioremediation.     

The oligopeptides production by the feather-degrading bacterium Bacillus methylotrophicus H0北大核心CSCD

Due to the high nutritive value of oligopeptides and the waste of feather resources, this study aimed at screening efficient strains of bacteria able to rapidly degrade feathers and produce large quantities of value-added oligopeptides. In order to assess the potential yield of oligopeptides, the promising strain H0 was selected from 16 feather-degrading microorganisms. To identify the strain, we analyzed the morphological and physiological characteristics of different strains, and carried out a gene sequence analysis of their 16S rRNAs. A single factor experiment was used to promote feather degradation and oligopeptide production, and the characteristics of the oligopeptides produced were also analyzed by Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). The strain was identified as Bacillus methylotrophicus. The optimal initial pH and temperature for oligopeptide production were 11 and 40 °C, respectively. After 72 h of fermentation under these optimal conditions, the feathers were almost completely degraded, with a 38.19% of oligopeptides (accounting for 67.53% of the total soluble peptides) and a 11.11% of free amino acids produced. LC-MS/MS analysis indicated that the oligopeptides were mainly short peptides containing 5-10 amino acids, with a molecular mass (Mr) of less than 1 300. Moreover, the peptides were abundant in branched-chain amino acids, that might be responsible for the antioxidant property of the feather hydrolysate. Our results demonstrate the great capability of B. methylotrophicus H0 in feather degradation and oligopeptide production. This research provides a high-quality microorganism resource, and the scientific basis for the development of feather-derived oligopeptide products. © 2018 Science Press. All rights reserved.     

Isolation,identification, and the degradation characteristics of a BDE-47 degrading strain北大核心CSCD

In an effort to remove BDE-47 residues from the environment, a bacterial strain that is capable of utilizing BDE-47 as the sole carbon source was isolated and screened from soil collected from an e-waste recycling area in Tianjin to analyze the degradation properties. The strain was preliminarily identified as Enterobacter sp. according to a 16S rDNA gene sequence analysis. The strain degraded 35.8% of 525 μg/L of BDE-47 in 35 d when the initial concentration of bacteria was 7.1 × 105 cells/ mL. The product of the biodegradation of BDE-47 was BDE-28. The biodegradation of BDE-47 fit well with first-order kinetics, and its degradation kinetics was ln Ct = - 0.104t + 6.22. With the addition of an electron acceptor, such as Fe3+, SO4 2- and NO3 -, the BDE-47 degradation rate was significantly increased to 49.8%, 59.1%, and 67.3%, respectively. The above results revealed that the strain could degrade BDE-47, which is of importance in the application of environmental bioremediation of BDE-47. © 2018 Science Press. All rights reserved.     

Screening and characterization of extremophiles in spacecraft assembly environment北大核心CSCD

Spacecrafts need to strictly control microorganisms before entering space flight. The Spacecraft Assembly, Integration, and Test Center (AITC) is an important environmental source for spacecrafts to carry microorganisms. The assembly clean room has characteristics of ventilation, dryness, and lack of nutrients that are not conducive to the growth and reproduction of microorganisms, except for extremophiles. In this study, based on the internal air and surface environment of the AITC in China, 13 strains of bacteria were identified by plate culture and 16S sequence analysis, and their extreme environmental tolerance, antibiotic resistance, and film-forming ability were tested. All these bacteria belonged to the Firmicutes and Proteobacteria phyla, and nine strains belonged to the Bacillus genus. All 13 strains of bacteria were salt-tolerant, acid-tolerant, and alkali-tolerant, and 69.2% of the bacteria survived heat shock at 80 ℃. Among these, one strain of Sphingomonas sp. JCM7513 isolated from the surface environment was insensitive to all the tested antibiotics and had strong drug resistance, while the other 12 strains were sensitive to most β-lactam antibiotics but had strong resistance to tetracyclic antibiotics and erythromycin. Most of the isolated bacteria exhibited strong biofilm-forming abilities. The study showed that there are a certain number of extremophiles in the spacecraft assembly environment. To protect spacecrafts from biological corrosion and planetary protection forward pollution, more effective monitoring and elimination methods are needed. © 2022 Science Press. All rights reserved.     

Bioremediation of highly contaminated oilfield soil: Bioaugmentation for enhancing aromatic compounds removal

This study evaluated the effectiveness of different amendments--including a commercial NPK fertilizer, a humic substance （HS）, an organic industrial waste （NovoGro）, and a yeast-bacteria consortium--in the remediation of highly contaminated （up to 6% of total petroleum hydrocarbons） oilfield soils. The concentrations of hydrocarbon, soil toxicity, physicochemical properties of the soil, microbial population numbers, enzyme activities and microbial community structures were examined during the 90-d incubation. The results showed that the greatest degradation of total petroleum hydro- carbons （TPH） was observed with the biostimulation using mixture of NPK, HS and NovoGro, a treatment scheme that enhanced both dehydrogenase and lipase activities in soil. Introduction of exogenous hydrocarbon-degrading bacteria （in addition to biostimulation with NPK, HS and NovoGro） had negligible effect on the removal of TPH, which was likely due to the competition between exogenous and autochthonous microorganisms. None- theless, the addition of exogenous yeast-bacteria consor- tium significantly enhanced the removal of the aromatic fraction of the petroleum hydrocarbons, thus detoxifying the soil. The effect of bioaugmentation on the removal of more recalcitrant petroleum hydrocarbon fraction was likely due to the synergistic effect of bacteria and fungi.     

Abundance and distribution of ammonia-oxidizing archaea in Tibetan and Yunnan plateau agricultural soils of China

As low oxygen and high ultraviolet （UV） exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea （AOA） in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR （q-PCR） and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria （AOB）, and characterize the community structures of AOA in the samples. The number of AOA cells （9.34 × 10^7-2.32× 10^8 g^-1 soil） was 3.86-21.84 times greater than that of AOB cells （6.91 × 10^6-1.24 × 10^8 g^-1 soil） in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall＇s correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.     

Responses of bacterial strains isolated from drinking water environments to N-acyl-L-homoserine lactones and their analogs during biofilm formation

Often as a result ofbiofilm formation, drinking water distribution systems （DWDS） are regularly faced with the problem of microbial contamination. Quorum sensing （QS） systems play a marked role in the regulation of microbial biofilm formation; thus, inhibition of QS systems may provide a promising approach to biofilm formation control in DWDS. In the present study, 22 bacterial strains were isolated from drinking water-related environments. The following properties of the strains were investigated： bacterial biofilm formation capacity, QS signal molecule N-acyl-L-homoserine lactones （AHLs） production ability, and responses to AHLs and AHL analogs, 3-chloro-4-（dichloromethyl）-5-hydroxy-2（5H）- furanone （MX） and 2（5H）-furanone. Four AHLs were added to developed biofilms at dosages ranging from 0.1 nmol.L J to 100nmol.L1. As a result, the biofilm growth of more than 1/4 of the isolates, which included AHL producers and non-producers, were significantly promoted. Further, the biofilm biomasses were closely associated with respective AHLs concentrations. These results provided evidence to support the idea that AHLs play a definitive role in biofilm formation in many of the studied bacteria. Meanwhile, two AHLs analogs demon- strated unexpectedly minimal negative effects on biofilm formation. This suggested that, in order to find an applicable QS inhibition approach for biofilm control in DWDS, the testing and analysis of more analogs is needed.     

Identification of pakchoi cultivars with low cadmium accumulation and soil factors that affect their cadmium uptake and translocation

The selection and use of low-Cd-accumulating cultivar （LCAC） has been proposed as one of the promising approaches in minimizing the entry of Cd in the human food chain. This study suggests a screening criterion of LCACs focusing on food safety. Pot culture and plot experiments were conducted to screen out LCACs from 35 pakchoi cultivars and to identify the crucial soil factors that affect Cd accumulation in LCACs. Results of the pot culture experiment showed that shoot Cd concentrations under the three Cd treatments significantly varied across cultivars. Two cultivars, Hualv 2 and Huajun 2, were identified as LCACs because their shoot Cd concentrations were lower than 0.2 mg. kg-1 under low Cd treatment and high Cd exposure did not affect the biomass of their shoots. The plot experiment further confirmed the consistency and genotypic stability of the low-Cd- accumulating traits of the two LCACs under various soil conditions. Results also showed that soil phosphorus availability was the most important soil factor in the Cd accumulation of pakchoi, which related negatively not only to Cd uptake by root but also to Cd translocation from root to shoot. The total Cd accumulation and translocation rates were lower in the LCACs than in the high-Cd cultivar, suggesting that Cd accumulation in different cultivars is associated with the Cd uptake by root as well as translocation from root to shoot. This study proves the feasibility of the application of the LCAC strategy in pakchoi cultivation to cope with Cd contamination in agricultural soils.     

Seasonal and interannual variation of soil respiration in four vegetation types in the loess hilly region北大核心CSCD

Soit carbon (C) stock is the largest C pool in terrestrial ecosystems, and the emission of CO2 through soil respiration contributes to the majority of soil C expenditure and atmospheric C. Soil respiration is also one of the major processes controlling the C budget of terrestrial ecosystems. A slight change in soil CO2 emission might cause drastic variations in global C balance. Therefore, it is of great significance to investigate the characteristics of soil respiration of soils growing different types of vegetation over a long period, and determine its relationship with variables such as soil temperature and moisture. The rate of soil respiration was measured each month in the growing seasons (from April to October) of 2011, 2013, and 2014 using the Li-8100 CO2 flux measurement system in the central Loess Plateau. Four types of vegetation (Quercus liaotungensis, Platycladus orientalis, Robinia pseudoacacia, and a natural shrub) were chosen for the periodical measurements. A permanent sample plot was established for each type of vegetation, and five polyvinyl chloride (PVC) collars were placed in each plot for the measurements. The temperature and water content of the soil in the upper 12 cm near the collar were measured using a digital soil temperature probe and a TDR 200 soil moisture meter at the same time when the soil respiration was measured. The soil respiration rates were fitted to the soil temperature and moisture with an exponential function, power function, linear function, and an equation combining the two variables. The results showed that: (1) the seasonal variation in the rates of soil respiration in the soils growing the four types of vegetation were almost the same, and were lower in the earlier period and then increased to high levels in the middle and later periods; (2) the rates of soil respiration in the same month varied with the type of vegetation grown, and were in the descending order: Q. liaotungensis > P. orientalis > shrub > R. pseudoacacia; (3) the average values of the rates of soil respiration in 2011, 2013, and 2014 were 2.77, 3.48, and 5.08 μmol m-2 s-1, respectively. The variation in soil respiration was higher across the three years than the variation for the types of vegetation grown; and (4) the rate of soil respiration was positively correlated to soil temperature and moisture for all the types of vegetation. A better fit was obtained by using the equation that included both the variables, soil temperature and moisture, than by an equation that included a single factor. Our results suggested that both seasonal and inter-annual variations of soil respiration occurred in the soils growing the four types of vegetation in the region. The temperature and water content of soils are the major regulating factors, and soil respiration in the Loess Plateau is more greatly affected by environment factors than by the type of vegetation. © 2018 Science Press. All rights reserved.     

Impacts of de-icing salt pollution on urban road greenspace: a case study of Beijing

De-icing salt contamination of urban soil and greenspace has been a common issue of concern in many countries for years. In the 2009/2010 winter, Beijing experienced a contamination accident resulting from the overuse of deicing salt, reported as almost 30000 tons, which severely damaged urban vegetation alongside roadways. The methods of sampling and rating for both soil contamination and response of the plant populations were developed to rapidly assess this emergency environmental event. Results showed that the shrubs were more severely damaged than the arbors in terms of both degree and extent, as almost all of the surveyed shrubs were severely damaged from the salt contamination, while only about 1/4 of the recorded arbors were rated as ＂severely injured＂ according to the integral plant injury index. The rating of the injury level showed that the trees like Pinus bungeana, Sophora japonica, and the shrubs like Euonymus japonicus, Sabina vulgaris showed less tolerance to de-icing salt pollution. The patterns of vegetation damage demonstrated that the ever-green shrubs alongside roads and the deciduous arbors in the center of roads were most vulnerable to the salt damage.     

Quantity and activity of ammonia-oxidizing archaea and bacteria and their contribution to ammonia oxidation in farmland soil of Qinghai-Tibet Plateau北大核心CSCD

Ammonia oxidation, the first and rate-limiting step of nitrification, is mainly performed by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). However, the activities of AOA and AOB in soil and their relative contribution to ammonia oxidation are unclear, and whether there is a significant correlation between the quantity of AOA and AOB and the ammonia oxidation rate is also controversial. In this study, quantitative PCR combined with acetylene (C2H2) and 1-octyne inhibition methods were used to determine the quantity and activity of AOA and AOB in wheat, highland barley, and oilseed rape soils in Nyingchi, Lhatse, Sangzhuzi, and Sangri counties on the Qinghai-Tibet Plateau. The results showed that the quantity of AOB ((2.34 ± 0.84) ×105 - (2.65 ± 1.07) ×106 copies g-1 dry soil) was significantly higher than that of AOA ((0.20 ± 0.10) ×104 - (4.02 ± 0.39) ×104 copies g-1 dry soil) in all the soil samples. Soil pH was the key factor affecting the quantity of AOB, and the total phosphorus and ammonium nitrogen in soil were the key factors affecting the quantity of AOA. The rates of ammonia oxidation in the farmland soils of Lhatse (2.42 ± 0.73 mg kg-1 d-1) and Sangzhuzi (3.24 ± 1.15 mg kg-1 d-1) were significantly higher than those in the soils of Nyingchi (1.17 ± 0.43 mg kg-1 d-1) and Sangri counties (0.88 ± 0.57 mg kg-1 d-1). The rates of ammonia oxidation in the farmland soils of Lhatse and Sangzhuzi were dominated by AOB, while those in the farmland soils of Nyingchi and Sangri counties were dominated by AOA. For crops, the ammonia oxidation rates of wheat and oilseed rape soils in all four regions were significantly higher than those of highland barley soil, whereas the activity of AOA and AOB was not influenced by crops. The ratio of nitrogen to phosphorus was the key factor influencing AOA activity, whereas soil pH and total carbon were the main factors influencing AOB activity. Additionally, the quantities of AOA and AOB were not significantly correlated with the total ammonia oxidation rates and AOA and AOB activity. Overall, our study suggests that both AOA and AOB play important roles in ammonia oxidation in farmland soils of the Qinghai-Tibet Plateau. Moreover, it is unreliable to predict the activity of AOA and AOB and their relative contribution to ammonia oxidation directly based on their number of amoA genes, and the activity of AOA and AOB should be directly and accurately measured. These results are important for understanding ammonia nitrogen removal processes, slowing nitrate loss, and reducing the emission of the greenhouse gas nitrous oxide in the farmland ecosystem of the Qinghai-Tibet Plateau. © 2022 Science Press. All rights reserved.     

Reuse of heavy metal-accumulating Cynondon dactylon in remediation of water contaminated by heavy metals

Phytoremediation technology is regarded as a simple and efficient way to remove heavy metals from contaminated soil. A reasonable disposal of metal hyperaccumulators is always and resource-saving. The a major issue in waste reuse heavy metal-accumulating Cynondon dactylon （L.） was investigated where heavy metals were desorbed by a facile acid-treatment. The result indicated that more than 90% of heavy metals （Zn, Pb and Cu） was extracted from Cynondon daetylon with 0.2 mmol· L^-1 HCl. The plant residue was used to adsorb heavy metals ions. The adsorption fitted the Langmuir isotherm model with the saturation adsorption capacity of 9.5 mg·g^-1 Zn^2＋, 36.2 mg·g^-1 Pb2＋ and 12.9 mg·g^-1 Cu^2＋, and the surface eomplexation and the backfilling of heavy metal imprinting cavities existed simultaneously during the adsorption. The treatment of wastewaters indicated that the plant residue exhibited a high removal rate of 97% for Cu. Also, the material could be recycled. The method offers a new disposal approach for heavy metal hyperaccumulator.     

Effects of bio-organic fertilizers on pineapple heart rot and bacterial community structure北大核心CSCD

Heart rot is a common soil-borne disease in the pineapple industry, but the situation can be alleviated by the application of bio-fertilizers with beneficial microbiomes. Clarifying the controlling mechanism of bio-organic fertilizer on the high incidence of heart rot is critical in monocultural pineapple cropping patterns. In our study, the soil of continuous cropping pineapple orchards was collected. Three types of carriers (rapeseed cake, peat soil, and coconut bran), biocontrol strains (Bacillus subtilis HL2 and Streptomyces strain HL3), and organic fertilizer (YJ) were composted into different bio-fertilizers (KC, KN, KY, LC, LN, and LY), which were used in pot experiments. The controlling effect of the bio-fertilizer was determined based on the response of pineapple heart rot and bacterial communities to different fertilizing methods. Our results revealed that the incidence of heart rot in bio-fertilizer KC was the lowest, which decreased by 20% and 13.3%, respectively, compared to HF (chemical fertilizer, 16-16-16) and YJ (organic fertilizer). The richness and diversity of soil bacterial communities in all biofertilized treatments (KC, KN, KY, LC, LN, and LY) were significantly higher than those in HF. However, the α-diversity indices of the bio-fertilizers (KC, KN, and KY) were higher than those of LC, LN, and LY, and the bacterial community composition was significantly different. The bacteria GP4, GP6, Bacillus, and Azohydromonas were enriched in KC, KN, and KY, while the relative abundance of Streptomyces increased significantly in LC, LN, and LY. Furthermore, Spearman correlation analysis showed that the relative abundance of these bacterial groups was significantly negatively correlated with the incidence of pineapple heart rot. In summary, the application of bio-organic fertilizers can decrease the incidence of pineapple heart rot by altering the soil bacterial community structure and stimulating beneficial soil microorganisms, which is important for reconstructing the ecological balance in continuous pineapple orchards. © 2022 Authors. All rights reserved.     

Screening and degradation characteristics of a tetracycline-degrading bacterial strain北大核心CSCD

Tetracycline is widely used in livestock and poultry breeding industry, which can cause serious problems to the environment. Antibiotic pollution has become an important environmental issue. This study aimed to isolate and identify a well-functioning tetracycline-degrading bacteria strain from activated sludge and to investigate its optimum degradation conditions. The strain was identified through morphological features, Gram staining, and the sequence analysis of 16S rRNA. Furthermore, the temperature, initial pH of the medium, inoculation amount, and type of metallic salt were analyzed to investigate the tetracycline degradation performance of the isolated strain. Based on the single factor test, the method of response surface analysis was adopted to optimize the degradation condition. The strain was named TTC-1 and identified as Klebsiella pneumoniae. The optimum condition for tetracycline degradation was determined as follows: temperature of 34.4 °C, pH of 7.22, and MnSO4 concentration of 0.32 g/L. Under this optimum condition, the predicted tetracycline degradation rate was 93.77%, whereas the observed value was 94.26%. The experimental results showed that the proposed model had high accuracy. TTC-1 showed a good performance in degrading tetracycline, which can provide reference for the bacteria during the biological treatment of tetracycline containing wastewater. © 2018 Science Press. All rights reserved.     

Isolation,identification, and the biodegradation characteristics of a benzoylurea insecticides-degrading strain北大核心CSCD

A chlorbenzuron, diflubenzuron, and hexaflumuron-degrading bacterium strain M6, was isolated from the activated sludge of an insecticide factory. The strain was identified as Achromobacter sp. according to an analysis on the 16S rRNA gene sequences, morphological, and physiological characteristics. Strain M6 could degrade more than 91% of 100 mg/L chlorbenzuron, diflubenzuron, and hexaflumuron within 48 hours, which could act as the sole carbon source. Strain M6 showed more chlorbenzuron degradation at a temperature range between 25 and 40 ℃ and a pH range between 6.0 and 8.0. The optimal temperature and the initial pH of medium for chlorbenzuron degradation by strain M6 were 30 ℃ and 7.0, respectively; the maximum chlorbenzuron tolerated concentration of strain M6 was as high as 400 mg/L. Strain M6 hydrolyzed 4-acetaminophenol into a purple-red product. Moreover, an approximately 1.4 kb DNA fragment, which could be expressed into an amidase to degrade amide pesticides, was amplified from the genomic DNA of strain M6. The results preliminarily proved that 3 benzoylurea insecticides could be degraded because of strain M6 hydrolyzing their amide bonds. This study obtained a highly efficient degrading strain and provided new resources and valuable information on benzoylurea insecticide degradation. © 2018 Science Press. All rights reserved.     

A new efficient azo dye-decolorizing bacterium Paenibacillus dendritiformis GGJ7 and its decolorization process北大核心CSCD

This paper aimed to find an efficient bacterium for decolorizing azo dyes. A strain which could decolorize Congo Red efficiently was isolated from Congo Red. The strain was identified as Paenibacillus dendritiformis GGJ7 (GGJ7, in short) by 16S rRNA gene sequence (NCBI accession No. KY655213). Strain GGJ7 was applied to the decolorization of azo dyes in this research, and influencing factors of decolorization were investigated, including diverse nutritional conditions, culture conditions (pH, temperature, oxygen conditions), and various dyes. The results demonstrated that the decolorization rate of Congo Red by strain GGJ7 was much higher than that of the other eight strains (e.g., YRJ1, YRJ2 etc.) in our previous work. The optimal conditions for Congo Red decolorization were 25 g/L LB broth as nutrient source, 30 °C, pH 7, and an anaerobic environment. The mechanism of decolorization was mainly biodegradation, and the decolorization process of strain GGJ7 was conformed to the first-class kinetics model: -ln (At /A0) = 0.6058t - 0.1082. For different azo dyes, the decolorization rate was up to 95%. Strain GGJ7 only needed 1 h to decolorize 50 mg/L Methyl Orange, 25 mg/L Croceine Scarlet, and 25 mg/L Methyl Red, needed 3 h to decolorize 50 mg/L Orange G and 50 mg/L Orange G6, and needed 4 h to decolorize 50 mg/L Congo Red. In summary, strain GGJ7 is an efficient azo dye-decolorizing bacterium, and it has a potential application in treating printing and dyeing wastewater. © 2018 Science Press. All rights reserved.     

Effects of stand density on understory species diversity and soil anti-scourability of Cupressus funebris plantation in Yunding Mountain,Sichuan, China北大核心CSCD

To protect the ecosystem of barren mountains, massive Cupressus funebris plantations were allowed in hilly areas of the central Sichuan Basin in the late 1980s. In recent years, Cupressus funebris plantations have faced problems such as biodiversity decline and soil erosion. To study the effects of different forest densities on understory species diversity and soil anti-scourability of Cupressus funebris plantations in Yunding Mountain, a typical sampling method was used to investigate the five different forest densities (1 100, 950, 800, 650, and 500 trees/hm2) and to analyze the correlation between the species diversity index, soil anti-scourability, and root index. In total, 176 species from 128 genera and 69 families were recorded in this area. The number of species in the herb layer was higher than that in the shrub layer. The species diversity index of the shrub layer first increased and then decreased with the decrease in stand density; and the species richness index D and Shannon–Wiener diversity index H showed peak values at a density of 650 trees/hm2. The species richness index D, Shannon–Wiener diversity index H, and Simpson dominance index H’ in the herb layer showed a bimodal trend of increasing, then decreasing, increasing again, and finally decreasing with the decrease in stand density; and the peak values were found at the densities of 650 and 950 trees/hm2. When soil anti-scourability decreased with stand density, it showed a trend of increasing and then decreasing, reaching a peak at a density of 650 trees/hm2. The positive correlation between the species richness index and soil anti-scourability was evident. Thus, 650 trees/hm2 is relatively more conducive to the stability of species diversity and soil anti-scourability in cypress plantations. © 2022 Authors. All rights reserved.     

Bacterial community structure in waterlogged bamboo slips excavated from the Laoguanshan Han Dynasty Tomb of Chengdu北大核心CSCD

To investigate the bacterial community structure features of soak solutions used to preserve bamboo slips that were excavated from Han dynasty tomb located in Laoguanshan of Chengdu and to reveal the diversity of bacteria in these soak solutions, PCR-DGGE was employed. Subsequently, the major DGGE bands were excised and sequenced to analyze the phylogeny of bacteria. The richness (S), Shannon-Wiener index (H), and Simpson index (D) of deionized water (0#) without the soaked bamboo slips were higher than those of the other samples. Among the bamboo slip soak solution samples, there were significant differences in these indicators; the bacterial genetic diversity of sample 121# was the highest and that of sample 1# was the lowest. Principal Component Analysis (PCA) showed that there were comparatively large differences among the samples, and the similarity between sample 1# and others was the lowest. Based on the sequence analysis, the major community of bacteria in soak solution were belonged to Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria, including Cupriavidus, Aquabacterium, Comamonas, Albidiferax, Hyphomicrobiaceae, Azospirillum, Nevskia, Streptococcus, Staphylococcus, Sediminibacterium, and Propionibacterium, among which Cupriavidus of the β-Proteobacteria class was detected in all samples. The bacterial community structure of the soak solutions that were collected from different bamboo slips was quite complex and significantly different. The analysis of the main bacterial community revealed the potential bacteria species that may trigger the damage in bamboo slips; the result provided a reference to prevent waterlogged bamboo slips from microbial diseases in the future. © 2018 Science Press. All rights reserved.     

Remediation of soil heavily polluted with polychlorinated biphenyls using a low-temperature plasma technique

Polychlorinated biphenyls （PCBs） were removed by low-temperature plasma technique （dielectric barrier discharge） from heavily polluted soil and their intermediate products were analyzed. The removal rate ranged from 40.1 to 84.6% by different treatments, and they were also influenced significantly （P 〈 0.01） by soil particle-size, electric power, gas flow rate and reaction time. The optimal reaction conditions of PCB removal from the soil were obtained experimentally when soil particle-size, electrical power, flow rate and reaction time were 5-10mm, 21w, 120mL. rain and 90rain, respectively. However, decreasing electrical power, flow rate and reaction time to 18 w, 60 mL. min- and 60 min respectively were also acceptable in view of the cost of remediation. This technique was characterized by the additional advantage of thorough oxidation of PCBs in the soil, with no formation of intermediate products after reaction. The technique therefore shows some promise for application in the remediation of soils contaminated with persistent organic pollutants in brown field sites in urban areas.     

Modeling agricultural non-point source pollution in a high-precipitation coastal area of China

Non-point source （NPS） pollution simulation in the high-precipitation coastal areas of China is difficult because varying annual typhoon incidence leads to highly contrasting rainfall patterns in dry years and wet years. An IMPULSE （Integrated Model of Non-point Sources Pollution Processes） based NPS model of the Changtan Reservoir watershed, which is a typical high-precipitation coastal area in China, was established based on the analysis of point and NPS pollution data, a digital elevation model, and data on land-use, soil, meteorology, economy, and agricultural management practice. Pre-processed pre-rain- fall soil moisture levels were introduced during the simulation to model the effects of typhoons on hydrology. Rainfall events were simulated sequentially through the year and the model was calibrated and verified using hydrological and water quality data. Accuracy of the simulated rainfall runoff and water quality in the Changtan watershed was found to be acceptable. The study showed that the NPS modeling system could be applied to the simulation and prediction ofNPS loadings in the Changtan Reservoir watershed.