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851.
Jianqing Tian Bing Wu Huai Chen Na Jiang Xiaoming Kang Xingzhong Liu 《Journal of Soils and Sediments》2017,17(12):2856-2865
Purpose
Fungi are essential components of soil microbial communities and have a crucial role in biogeochemical processes. Alpine regions are sensitive to climate change, and the importance of changes in fungal community composition along altitudinal gradients in alpine regions is hotly debated.Materials and methods
We used 454 pyrosequencing approaches to investigate the fungal communities at 1600, 2300, 2800, 3000, and 3900 m above sea level along an altitudinal gradient on Mount Gongga.Results and discussion
The results showed that Agaricomycetes, Sordariomycetes, and Tremellomycetes are the dominant classes at all sampling sites. Operational taxonomic unit richness decreased with increasing altitude, and the fungal communities were clustered into three groups that corresponded to altitudes of, i.e., 1600, 2300, and above 2800 m. The evenness of fungi was not significantly correlated with altitude, whereas beta diversities were significantly correlated with altitude. The distance-based redundancy analysis and Mantel test indicated that the composition of fungal assemblages was mostly driven by altitude and temperature.Conclusions
Our results indicated that ecological processes possibly related to altitude and temperature play an important role in structuring fungal biodiversity along the elevational gradient. Our results highlight that different microbes may respond differently to environmental gradients.852.
Organic geochemical parameters for estimation of petrogenic inputs in the coastal area of Kavala City,Greece 总被引:1,自引:0,他引:1
Anna Grigoriadou Jan Schwarzbauer Andreas Georgakopoulos 《Journal of Soils and Sediments》2008,8(4):253-262
Background, aims, and scope Sediments and soils in coastal areas are frequently polluted by anthropogenic contaminants as the result of both riverine
or terrestrial discharge and autochthonic marine emissions. In order to determine petrogenic contamination in the coastal
industrial area of Kavala City in northern Greece, a combination of polycyclic aromatic hydrocarbon (PAH) and organic geochemical
petroleum biomarker analyses has been performed on marine and freshwater sediments as well as soils.
Materials and methods Soils, freshwater, and marine sediments have been treated by standard extraction methods. The dried and desulphurized sample
extracts have been fractionated by column chromatography, followed by addition of surrogate standards. Qualitative and quantitative
data were obtained by gas chromatograph connected with a flame ionization and electron capture detector (GC-FID/ECD) and by
GC linked to a mass spectrometer (GC/MS), whereas identification of compounds was based on EI+-mass spectra and gas chromatographic retention times. Quantitative data were obtained by integration of specific ion chromatograms.
Results The total PAH concentrations measured in the area varied highly, showing different levels from 18 up to 318,000 ng g−1 dry weight (dw). Several PAH ratios, as well as the ratio of pristane (Pr) to phytane (Phyt), have been considered. Out of
39 samples, 22 revealed a specific distribution of hopane fingerprints indicating petrogenic input. Finally, in numerous samples,
the ratio of 17α(H)-22,29,30-trisnorhopane (Tm) and 18α(H)-22,29,30-trisnorhopane (Ts) was calculated, as well as the ratio
of 22S-17α(H),21β(H)-30 homohopane (αβC31-hopane 22S) and 22R-17α(H),21β(H)-30 homohopane (αβC31-hopane 22R).
Discussion Based on the specific PAH ratios, a group of samples was clearly characterized to be contaminated dominantly by combustion-derived
emissions, whereas a second group of samples exhibited mixed influence from petrogenic and pyrogenic PAHs. On the other hand,
the exhibition of specific hopane fingerprints in many samples indicates a direct petrogenic input. Finally, the values of
the ratio of Tm/(Ts + Tm) and of αβC31-hopanes 22S/(22S+22R)-isomer demonstrated an input of highly mature organic matter that has to be clearly attributed to petroleum-derived
contamination, while the ratio of Pr/Phyt showed that most samples exhibited an input of organic matter.
Conclusions The coastal area of Kavala is strongly affected by anthropogenic contaminants. Petrogenic emissions were pointed out firstly
by PAH analyses that separated dominantly pyrogenic contaminated sites from areas affected by both pyrogenic and petrogenic
emissions. However, analyses of organic geochemical biomarkers revealed a much higher sensitivity in identifying petroleum-derived
contaminations and were successfully used to differentiate several petrogenic contaminations in the marine and terrestrial
samples.
Recommendations and perspectives Based on this study, it was recommended to use a complementary approach of source-specific substances to successfully characterize
petrogenic emissions. Generally, a PAH-based source identification of petrogenic versus pyrogenic contaminations should be
combined with petroleum biomarker analysis. PAH and biomarker ratios as well as individual biomarker fingerprints revealed
a more comprehensive view on the quality and quantity of petrogenic emissions in sediments and soils. 相似文献
853.
854.
Ji-Zheng He Yong Zheng Cheng-Rong Chen Yuan-Qiu He Li-Mei Zhang 《Journal of Soils and Sediments》2008,8(5):349-358
Background, aim, and scope Fertilization is an important agricultural practice for increasing crop yields. In order to maintain the soil sustainability,
it is important to monitor the effects of fertilizer applications on the shifts of soil microorganisms, which control the
cycling of many nutrients in the soil. Here, culture-dependent and culture-independent approaches were used to analyze the
soil bacterial and fungal quantities and community structure under seven fertilization treatments, including Control, Manure,
Return (harvested peanut straw was returned to the plot), and chemical fertilizers of NPK, NP, NK, and PK. The objective of
this study was to examine the effects on soil microbial composition and diversity of long-term organic and chemical fertilizer
regimes in a Chinese upland red soil.
Materials and methods Soil samples were collected from a long-term experiment station at Yingtan (28°15′N, 116°55′E), Jiangxi Province of China.
The soil samples (0–20 cm) from four individual plots per treatment were collected. The total numbers of culturable bacteria
and fungi were determined as colony forming units (CFUs) and selected colonies were identified on agar plates by dilution
plate methods. Moreover, soil DNAs were extracted and bacterial 16S rRNA genes and fungal 18S rRNA genes were polymerase chain
reaction amplified, and then analyzed by denaturing gradient gel electrophoresis (DGGE), cloning, and sequencing.
Results The organic fertilizers, especially manure, induced the least culturable bacterial CFUs, but the highest bacterial diversity
ascertained by DGGE banding patterns. Chemical fertilizers, on the other hand, had less effect on the bacterial composition
and diversity, with the NK treatment having the lowest CFUs. For the fungal community, the manure treatment had the largest
CFUs but much fewer DGGE bands, also with the NK treatment having the lowest CFUs. The conventional identification of representative
bacterial and fungal genera showed that long-term fertilization treatments resulted in differences in soil microbial composition
and diversity. In particular, 42.4% of the identified bacterial isolates were classified into members of Arthrobacter. For fungi, Aspergillus, Penicillium, and Mucor were the most prevalent three genera, which accounted for 46.6% of the total identified fungi. The long-term fertilization
treatments resulted in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent
approaches.
Discussion It was evident that more representative fungal genera appeared in organic treatments than other treatments, indicating that
culturable fungi were more sensitive to organic than to chemical fertilizers. A very notable finding was that fungal CFUs
appeared maximal in organic manure treatments. This was quite different from the bacterial CFUs in the manure, indicating
that bacteria and fungi responded differently to the fertilization. Similar to bacteria, the minimum fungal CFUs were also
observed in the NK treatment. This result provided evidence that phosphorus could be a key factor for microorganisms in the
soil. Thus, despite the fact that culture-dependent techniques are not ideal for studies of the composition of natural microbial
communities when used alone, they provide one of the more useful means of understanding the growth habit, development, and
potential function of microorganisms from soil habitats. A combination of culture-dependent and culture-independent approaches
is likely to reveal more complete information regarding the composition of soil microbial communities.
Conclusions Long-term fertilization had great effects on the soil bacterial and fungal communities. Organic fertilizer applications induced
the least culturable bacterial CFUs but the highest bacterial diversity, while chemical fertilizer applications had less impact
on soil bacterial community. The largest fungal CFUs were obtained, but much lower diversity was detected in the manure treatment.
The lowest bacterial and also fungal CFUs were observed in the NK treatment. The long-term fertilization treatments resulted
in different bacterial and fungal compositions ascertained by the culture-dependent and also the culture-independent approaches.
Phosphorus fertilizer could be considered as a key factor to control the microbial CFUs and diversity in this Chinese upland
red soil.
Recommendations and perspectives Soil fungi seem to be a more sensitive indicator of soil fertility than soil bacteria. Since the major limitation of molecular
methods in soil microbial studies is the lack of discrimination between the living and dead, or active and dormant microorganisms,
both culture-dependent and culture-independent methods should be used to appropriately characterize soil microbial diversity. 相似文献
855.
A wild tetraploid oat Avena maroccana Gdgr. was collected from the 11 populations in the periphery of Rommani and Casablanca geographic groups of Morocco. Genetic
diversity of the species was investigated using six allozyme systems. Allelic frequencies were scored representing eight polymorphic
and five monomorphic loci. Coefficient of gene differentiation (Gst) was 0.3019, which indicated great genetic differentiation. The number of alleles per locus was 2.6154, the percentage of
polymorphic loci was 61.54, and the expected heterozygosity was 0.2462 in all populations. Genetic diversity in A. maroccana was high in comparison to self-pollinated species. In total, nine heterozygotes resulting from outcrossing were found in
the progeny from M1, M3, M4, M22 and M26. The population of M7 had peculiar alleles Pgd–2SS and Pgd-1SS in high frequency. M9 had the lowest level of diversity out of the 11 populations. Geographic and genetic distances between
all the populations were not significantly correlated with each other (r = 0.0996). Cluster analysis showed that two groups, (M1, M22, M2 and M4) and (M3, M23, M8, M5 and M26) were apparently differentiated.
Two populations of the Casablanca group, M7 and M9 were independent from each other, and were separated distinctly from the
other populations. Genetic diversity of the Rommani and Casablanca groups was almost the same in all the parameters. This
was due to the similar man-made habitat such as roadside or rich fertile soil and brown clay soils. The population size of
A. maroccana was small and restricted to the narrow central Morocco with great genetic differentiation so that genetic diversity may be
reflected from the results of genetic drift and outcrossing heterozygote segregation. 相似文献
856.
An understanding of the effects of salinity and sodicity on soil carbon (C) stocks and fluxes is critical in environmental
management, as the areal extents of salinity and sodicity are predicted to increase. The effects of salinity and sodicity
on the soil microbial biomass (SMB) and soil respiration were assessed over 12weeks under controlled conditions by subjecting
disturbed soil samples from a vegetated soil profile to leaching with one of six salt solutions; a combination of low-salinity
(0.5dSm−1), mid-salinity (10dSm−1), or high-salinity (30dSm−1), with either low-sodicity (sodium adsorption ratio, SAR, 1), or high-sodicity (SAR 30) to give six treatments: control (low-salinity
low-sodicity); low-salinity high-sodicity; mid-salinity low-sodicity; mid-salinity high-sodicity; high-salinity low-sodicity;
and high-salinity high-sodicity. Soil respiration rate was highest (56–80mg CO2-C kg−1 soil) in the low-salinity treatments and lowest (1–5mg CO2-C kg−1 soil) in the mid-salinity treatments, while the SMB was highest in the high-salinity treatments (459–565mg kg−1 soil) and lowest in the low-salinity treatments (158–172mg kg−1 soil). This was attributed to increased substrate availability with high salt concentrations through either increased dispersion
of soil aggregates or dissolution or hydrolysis of soil organic matter, which may offset some of the stresses placed on the
microbial population from high salt concentrations. The apparent disparity in trends in respiration and the SMB may be due
to an induced shift in the microbial population, from one dominated by more active microorganisms to one dominated by less
active microorganisms. 相似文献
857.
Goal, Scope and Background
Distribution of hydrophobic organic contaminants in abiotic compartments is essential for describing their transfer and fate in aquatic ecosystems. Taihu Lake is the third largest freshwater lake in China. Water quality of Taihu Lake has deteriorated greatly during the last decades and has threatened the water supply. The aim of the present study was to investigate the partitioning of polycyclic aromatic hydrocarbons (PAHs) among overlying water, suspended particulate matter (SPM), sediments, and pore water in Meiliang Bay, Taihu Lake and to provide useful information for the ecological engineering in this area.Materials and Methods
Overlying water and surface sediment were sampled from six sites in Meiliang Bay, Taihu Lake, China. Within 72 h of sampling, sediments were centrifuged to obtain the pore water. Overlying water samples were filtered to separate dissolved and SPM samples. After extraction, samples were purified following a clean-up procedure. PAH fraction was obtained by elution with a mixture of hexane: DCM (7:3, V/V) and analyzed by GC/MS.Results
PAHs concentrations in overlying water varied from 37.5 ng/L to 183.5 ng/L. Concentrations of PAHs in pore water were higher than those in overlying water. The total concentrations of 16 priority PAHs in sediments ranged from 2091.8 ng/g-dw to 4094.4 ng/g-dw. PAHs concentrations on SPM were decreased with suspended solid concentrations (SSC). Total PAHs concentrations on SPM varied in the range of 3369.6 ng/g-dw to 7531.1 ng/g-dw. The partition coefficients between sediment and overlying water (log K oc) for PAHs with log K ow<5 were positively correlated with their octanol-water partition coefficients (log K ow) (n=39, r=0.79, p<0.0001). Partition coefficients between sediment and pore water (log K oc′) for all PAHs were also significantly correlated with their log K ow values (n=48, r=0.82, p<0.0001).Discussion
In general, PAHs derived from combustion sources tend to bind strongly to soot particles in natural sediment. Consequentially, K oc values observed in the natural environment could be orders of magnitude higher than those predicted by linear correlation relationships under laboratory conditions. In the present study, the ratio of log K oc values to log K ow values falls consistently above 1, indicating that the sediment soot carbon in the bay was more attractive for PAHs than n-octanol. The log K oc′ was also higher than that predicted under laboratory conditions, suggesting that the measured pore water PAH concentrations were lower than those predicted. That is to say, not all the sediment PAHs can be available to partition rapidly into sediment pore waters. A variation in soot content is a possible reason. Furthermore, concentrations of PAHs on SPM were higher than those in sediments. The compositions of PAHs on SPM and in sediments were similar, indicating the importance of re-suspension process of sediments in the partitioning process of the shallow lake.Conclusions
The results indicated the equilibrium partitioning model could be used to predict PAHs distribution in various phases of a shallow lake in the stagnation period, but re-suspension processes should be considered to modify the relationship between log K ocs and log K ows.Recommendations and Perspectives
Concentration, particle size and composition of resuspended particles could affect the relationship between log K ocs and log K ows. Further work should be done under field conditions, especially where a steady thermodynamic equilibrium state could be assumed.858.
Shahla Hosseini Bai Timothy J. Blumfield Zhihong Xu Chengrong Chen Clyde Wild 《Journal of Soils and Sediments》2012,12(3):386-395
Purpose
There is considerable interest in finding a cost-effective method of site preparation that effectively controls weeds during planting and further reduces the need for recurring herbicide applications. In this study, two weed control methods, herbicide and scalping, were examined. Both methods may have implications for soil organic matter (SOM) dynamics and nitrogen (N) which could consequently affect plant survival and vegetation establishment. This study aimed to investigate the dynamics of SOM, carbon (C) and N pools under site manipulation practices and the associated early plant survival and growth in tropical Australia. 相似文献859.
Ali Sdiri Teruo Higashi Rochdi Chaabouni Fakher Jamoussi 《Water, air, and soil pollution》2012,223(3):1191-1204
A batch sorption method was used to study the removal of few toxic metals onto the Late Cretaceous clays of Aleg formation
(Coniacian–Lower Campanian system), Tunisia, in single, binary and multi-component systems. The collected clay samples were
used as adsorbents for the removal of Pb(II), Cd(II), Cu(II) and Zn(II) from aqueous solutions. Results show that the natural
clay samples were mainly composed of silica, alumina, iron and magnesium oxides. N2-adsorption measurements indicated mesoporous materials with modest specific surface area of <71 m2/g. Carbonate minerals were the most influencing parameters for heavy metal removal by natural clays in both single and multi-element
systems. The affinity sequence was Pb(II)>Cu(II)>Zn(II)>Cd(II) due to the variable physical properties of the studied metals.
The maximum adsorption capacity reached 131.58 mg/g in single systems, but decreased to <50.10 mg/g in mixed systems. In single,
binary and muti-element systems, the studied clay samples removed substantial amounts of heavy metals, showing better effectiveness
than the relevant previous studies. These results suggest that the studied clay samples of the Late Cretaceous clays from
Tunisia can be effectively used as natural adsorbents for the removal of toxic heavy metals in aqueous systems. 相似文献
860.