共查询到20条相似文献,搜索用时 31 毫秒
1.
Dario Liberati Paolo Sconocchia Anna Ricci Giovanni Gigliotti Chiara Tacconi Paola Grenni Sara Tariciotti Anna Barra Caracciolo Angelo Massacci Alessandra Lagomarsino Paolo De Angelis 《Journal of Soils and Sediments》2018,18(6):2292-2304
Purpose
Leaf transpiration drives many of the processes involved in phyto-technologies, and it can represent a useful mechanism to remove water from different kind of storage basins presenting inorganic, organic or microbiological contamination (phyto-dehydration), with the aim to reduce the risk of environmental contamination. In this framework, a mesocosm-scale trial was carried out to test the capacity of different helophyte species to reduce the excess of water in an artificial pond filled with oversaturated sludge.Materials and methods
The sludge derives from the digestion of pig slurries, presents high levels of zinc and copper and for most of the year is covered by a water layer of about 20 cm due to rainfalls. This layout (water layer over the sludge) was reproduced inside the mesocosms, where four helophyte species (Phragmites australis and a mix of Carex acutiformis, Iris pseudacorus and Juncus effusus) were planted on floating frames. Plant growth and functionality were monitored for one year, along with their water consumption capacity; the vegetation impact on sludge chemistry, sludge microbial community and sludge greenhouse gases emission/uptake were also evaluated. The sensitivity of the phyto-dehydration system to the reduction of water level occurring during summer in the pond was investigated reducing the water input to the mesocosms.Results and discussion
P. australis and C. acutiformis successfully established in the mesocosms, while a significant mortality was recorded for I. psudacorus and J. effusus. Once established, plants were able to grow in the mesocosms, and no metal toxicity effect was observed on photosynthesis rates that were comparable with values reported for natural stands of the species. Plants significantly increased (from 24 to 63%, depending on the species) the amount of water lost by the mesocosms and counteracted the reduction of sludge organic carbon that could lead to a mobilization of the heavy metals bound to organic matter: furthermore, plants decreased the rates of mesocosm greenhouse gas emission and reduced the sludge pathogen (Enterobacteriaceae) occurrence. Water limitations reversibly reduced the water consumption and CO2 uptake capacity of the mesocosms.Conclusions
The results of this study demonstrated that the water balance of a sludge/water system can be effectively modified through the phyto-dehydration approach, increasing significantly the amount of water lost. Although the low tolerance of two species to the sludge/water environment after plantation needs to be further investigated, this phyto-technology can represent a promising approach to manage the excess of water in polluted ponds.2.
Kobra Mahdavian Seyed Majid Ghaderian Masoud Torkzadeh-Mahani 《Journal of Soils and Sediments》2017,17(5):1310-1320
Purpose
This study investigated the extent of metal accumulation by plants colonizing a mining area in Yazd Province in Central Iran. It also investigated the suitability of these plants for phytoextraction and phytostabilization as two potential phytoremediation strategies.Materials and methods
Plants with a high bioconcentration factor (BCF) and low translocation factor (TF) have the potential for phytostabilization, whereas plants with both BCFs and TFs >1 may be appropriate for phytoextraction. In this study, both shoots and roots of 40 plant species and associated soil samples were collected and analyzed for total concentrations of trace elements (Pb, Zn, and Ag). BCFs and TFs were calculated for each element.Results and discussion
Nonnea persica, Achillea wilhelmsii, Erodium cicutarium, and Mentha longifolia were found to be the most suitable species for phytostabilization of Pb and Zn. Colchicum schimperi, Londesia eriantha, Lallemantia royleana, Bromus tectorum, Hordeum glaucum, and Thuspeinantha persica are the most promising species for element phytoextraction in sites slightly enriched by Ag. Ferula assa-foetida is the most suitable species for phytostabilization of the three studied metals. C. schimperi, L. eriantha, L. royleana, B. tectorum, M. longifolia, and T. persica accumulated Ag, albeit at low level.Conclusions
Our preliminary study shows that some native plant species growing on this contaminated site may have potential for phytoremediation.3.
Mohammad Wahsha Mandana Nadimi-Goki Claudio Bini 《Journal of Soils and Sediments》2016,16(4):1300-1305
Purpose
The present paper concerns the distribution and mobility of heavy metals (Cu, Pb, Zn and Fe) in the soils of some abandoned mine sites in Italy and their transfer to wild flora.Materials and methods
Soils and plants were sampled from mixed sulphide mine dumps in different parts of Italy, and the concentrations of heavy metals were determined.Results and discussion
The phytoremediation ability of Salix species (Salix eleagnos, Salix purpurea and Salix caprea), Taraxacum officinale and P?lantago major for heavy metals and, in particular, zinc was estimated. The results showed that soils affected by mining activities presented total Zn, Cu, Pb and Fe concentrations above the internationally recommended permissible limits. A highly significant correlation occurred between metal concentrations in soils.Conclusions
The obtained results confirmed the environmental effects of mine waste; exploring wild flora ability to absorb metals, besides metal exploitation, proved a useful tool for planning possible remediation projects.4.
Xueping Chen Hao Ma Yu Zheng Jiamiao Liu Xia Liang Chiquan He 《Journal of Soils and Sediments》2017,17(1):181-189
Purpose
The dynamics and uncertainties in wetland methane budgets affected by the introduction of Alnus trabeculosa H. necessitate research on production of methane by methanogenic archaea and consumption by methane-oxidizing microorganisms simultaneously.Materials and methods
This study investigated methane emission in situ by the closed chamber method, and methanogenic and methanotrophic communities using denatured gradient gel electrophoresis (DGGE) and quantitative PCR based on mcrA (methyl coenzyme M reductase), pmoA (particulate methane monooxygenase) genes in the rhizosphere and non-rhizosphere soils in the indigenous pure Phragmites australis T., and A. trabeculosa–P. australis mixed communities in Chongxi wetland.Results and discussion
Methane flux rate from the pure P. australis community was 2.4 times larger than that of A. trabeculosa–P. australis mixed community in the rhizosphere and 1.7 times larger in the non-rhizosphere, respectively. The abundance of methanogens was lower in the mixed community soils (3.56?×?103–6.90?×?103 copies g?1 dry soil) compared with the P. australis community (1.47?×?104–1.89?×?104 copies g?1 dry soil), whereas the methanotrophs showed an opposite trend (2.08?×?106–1.39?×?106 copies g?1 dry soil for P. australis and 6.20?×?106–1.99?×?106 copies g?1 dry soil for mixed community soil). A liner relationship between methane emission rates against pmoA/mcrA ratios (R 2?=?0.5818, p?<?0.05, n?=?15) was observed. The community structures of the methane-cycling microorganism based on mcrA and pmoA suggested that acetoclastic methanogens belonging to Methanosarcinaceae and a particular type II methanotroph, Methylocystis, were dominant in these two plant communities.Conclusions
The introduction of A. trabeculosa would promote the proliferation of methanotrophs, especially the dominant Methylocystis, but not methanogens, ultimately diminishing methane emission in the wetland.5.
Elizabeth J. Lam María E. Gálvez Manuel Cánovas Ítalo L. Montofré Brian F. Keith 《Journal of Soils and Sediments》2018,18(6):2203-2216
Purpose
The objective of this work was to identify hyperaccumulator plants and evaluate their capacity on copper mine tailings in the Antofagasta Region (Chile), considered one of the most arid in the world.Materials and methods
Two native plant species, Gazania rigens and Pelargonium hortorum, were grown during 11 weeks on mine tailings. The physico-chemical characterization of the mine tailings under study indicated that the substrate required conditioning to support a phytoremediation system. In this respect, organic and inorganic amendments and mycorrizhal fungi were added to the substrate. Three treatments were designed to assess the effects of the amendments through an analysis of variance.Results and discussion
Indicators of plant growth and development were measured weekly, and concentrations of Cd, Cu, Fe, Mn, Pb, Al, and Zn in roots of tailing-grown plants and substrate were measured at the end of the experiment.Conclusions
The results were used to determine the bioconcentration factor (BCF), which demonstrated that both species act as excluders of Fe, Mn, Pb, Al, and Zn. In addition, it was found that both species present characteristics of potential accumulators of Cu.6.
Li -Juan Chen Qi Feng Yong-Ping Wei Chang-Sheng Li Yan Zhao Hui-Ya Li Bao-Gui Zhang 《Journal of Soils and Sediments》2017,17(2):376-383
Purpose
Irrigation and fertilization can change soil environment, which thereby influence soil microbial metabolic activity (MMA). How to alleviate the adverse effects by taking judicious saline water irrigation and fertilization regimes is mainly concerned in this research.Materials and methods
Here, we conducted a field orthogonal designed test under different saline water irrigation amount, water salinity, and nitrogen fertilizer application. The metabolic profiles of soil microbial communities were analyzed by using the Biolog method.Results and discussion
The results demonstrated that irrigation amount and fertilizer application could significantly change MMA while irrigation water salinity had no significant effect on it. Medium irrigation amount (30 mm), least (50 kg ha?1) or medium (350 kg ha?1) N fertilizer application, and whatever irrigation water salinity could obtain the optimal MMA. Different utilization rates of carbohydrates, amino acids, carboxylic acids, and polymers by soil microbial communities caused the differences of the effects, and D-galactonic acid γ-lactone, L-arginine, L-asparagine, D-glucosaminic acid, Tween 80, L-threonine, and D-galacturonic acid were the indicator for distinguishing the effects.Conclusions
The results presented here demonstrated that by regulating irrigation water amount and fertilizer application, the effects of irrigation salinity on MMA could be alleviated, which offered an efficient approach for guiding saline water irrigation.7.
Shunbao Lu Yanjie Zhang Chengrong Chen Zhihong Xu Xiaomin Guo 《Journal of Soils and Sediments》2017,17(4):985-995
Purpose
Plantation is an important strategy for forest restoration and carbon (C) storage. Plantations with different tree species could significantly affect soil properties, including soil pH, soil nutrient content, soil microbial activities, and soil dissolved organic C. Changes in these abiotic and biotic factors could regulate mineralization of soil organic C (SOC). However, it remains unclear to what extent these factors affect the mineralization of SOC under different tree species plantations.Materials and methods
Soil was collected at 0–10 cm depth from plantations with Pinus elliottii Engelm. var. elliottii, Araucaria cunninghamii, and Agathis australis, respectively, in southeast Queensland, Australia. Soil samples were assayed for soil organic C; organic N and mineralization of SOC; soil particle size; total C, N, and P; and pH. In addition, a 42-day laboratory incubation with substrate additions was done to examine the influence of different substrates and their combinations on bio-available organic C.Results and discussion
Our results suggested that SOC mineralization was mainly determined by soil pH and soil C content among plantations with different tree species, whereas SOC mineralization was not correlated with soil N and P contents. These results were further confirmed by the substrate addition experiments. SOC mineralization of soils from slash pine showed greater response to C (glucose) addition than soils from other two plantations, which suggested significant differences in SOC mineralization among plantations with different tree species. However, neither N addition nor P addition had significant effects on SOC mineralization.Conclusions
Our results indicated that plantations with different tree species substantially affect the mineralization and stability of soil organic C pool mainly by soil pH and soil C content.8.
Manoj Kumar Vivek Kumar Ajit Varma Ram Prasad Amarish Kumar Sharma Abhradip Pal Anfal Arshi Joginder Singh 《Journal of Soils and Sediments》2016,16(8):2118-2127
Purpose
The synthetic soil based bioremediation approach as reasonable and sustainable practice at the farming level where desired bioremediation could be established at lower cost.Materials and methods
Metal-tolerant bacteria from different environmental field samples, (a) a municipal dump site, (b) an agricultural field and (c) sludge of electro-plating industries, were screened and characterized. Bioremediation of metal contaminants through isolated bacteria was compared under two different conditions, synthetic soil and basic minimal media containing copper, cobalt and nickel.Results and discussion
The pollutants arising from industrial effluents are imparting a huge negative impact on agricultural land. Microbes are predominant in heavy metal-contaminated sites, which signifies as a potential opportunity for the researchers towards bioremediation. Three bacterial species showed high metal tolerance; 16S ribosomal DNA (rDNA) analysis revealed that the organisms were Proteus vulgaris strain, Stenotrophomonas sp. and Bacillus thuringiensis. Percentage removal of metals was also analysed under different concentrations and pH.Conclusions
The current tested methods are helpful in streamlining the natural compliance of fragile elements and its uptake into the microbial system under in vitro and in situ conditions.9.
Haroldo Lobo Leire Méndez-Fernández Maite Martínez-Madrid Michiel A. Daam Evaldo L. G. Espíndola 《Journal of Soils and Sediments》2016,16(12):2766-2774
Purpose
This study aimed at evaluating the acute effects of arsenic and zinc to the warmwater aquatic oligochaete Branchiura sowerbyi. Relative sensitivity with the coldwater species Tubifex tubifex was compared. Implications for the use of B. sowerbyi in the risk assessment of sediments in the tropics are discussed.Materials and methods
Water-only (96 h) and sediment (14 days) toxicity tests were conducted with both species evaluating a concentration series of arsenic and zinc. The tests were conducted considering the environmental conditions in the natural habitat of T. tubifex (predominantly temperate) and B. sowerbyi (predominantly tropical). Both lethal and sublethal endpoints (autotomy of the posterior body parts, abnormal behavior and appearance) were determined in the tests. The lethal (LC10 and LC50) and effect (EC10 and EC50) concentrations were also determined to assess metal sensitivity for both species.Results and discussion
Both test species were more sensitive to Zn than As in water-only tests, which is in agreement with previous studies evaluating the toxicity of these metals to aquatic oligochaetes. Sublethal effects were generally noted at concentrations lower than those leading to mortality. The warmwater oligochaete B. sowerbyi was more sensitive to both metals tested than the coldwater species T. tubifex.Conclusions
Study findings support the need for using indigenous tropical species in risk assessments in the tropics. In addition, sublethal effect parameters should be included in toxicity testing with aquatic oligochaetes.10.
Yaling Zhang Carl Menke Barbara Drigo Shahla Hosseini Bai Ian Anderson Zhihong Xu Hong Chen Manyun Zhang 《Journal of Soils and Sediments》2017,17(10):2410-2419
Purpose
Re-establishment of soil nitrogen (N) capital is a priority in mine rehabilitation. We aimed to evaluate the effects of biochar addition on improving mine spoil N pools and the influence of elevated CO2 concentration on mine rehabilitation.Materials and methods
We assessed the effects of pinewood biochar, produced at three temperatures (650, 750 and 850 °C, referred as B650, B750 and B850, respectively), on mine spoil total N concentrations with five different plant species, including a tree species (Eucalyptus crebra), N-fixing shrubs (Acacia floribunda and Allocasuarina littoralis) and C3 and C4 grasses (Austrodanthonia tenuior and Themeda australis) incubated at ambient (400 μL L?1) and elevated (700 μL L?1) atmospheric CO2 concentrations, as well as the effects of elevated CO2 on mine rehabilitation.Results and discussion
Soil total N significantly improved following biochar incorporation under all plant species (P < 0.05) except for T. Australis. E. crebra had the highest soil total N (0.197%, 0.198% and 0.212% for B650, B750 and B850, respectively). Different from the negligible influence of elevated CO2 on soil properties under the grasses and the N-fixing shrubs, elevated CO2 significantly increased soil water and hot water extractable organic C (WEOC and HWEOC, respectively) and decreased total C under E. crebra, indicating that the nutrient demands were not met.Conclusions
Biochar addition showed the potential in mine rehabilitation in terms of improving soil N pool, especially with E. crebra. However, it would be more difficulty to rehabilitate mine spoils in future with the rising atmospheric CO2 concentration.11.
Jia Tu Kim McGrouther Hailong Wang Tianle Ma Jie Qiao Lichao Wu 《Journal of Soils and Sediments》2017,17(9):2371-2382
Purpose
Paulownia, one of the fastest growing broad-leaved tree species in the world, is widely distributed in the warm temperate regions of China. However, there are few commercial-scale Paulownia plantations, and there is only limited information available about the most suitable soil quality for Paulownia fortunei growth in mid-subtropical, Hunan Province, China.Materials and methods
To understand the effect of the growth of P. fortunei on soil conditions, 25 soil property parameters under Paulownia plantations were studied in Hunan Province, China. Seventy-two standard plots of eight different stand types were analyzed by three statistical approaches to assess soil quality (SQ) in the different P. fortunei plantations.Results and discussion
The results revealed that a majority of the soil characteristics when intercropping with oilseed rape and the pure P. fortunei (plantation III) were better than intercropping with Camellia oleifera, orange trees, and Cunninghamia lanceolata (Lamb.). Available calcium, available magnesium, available potassium, available phosphorus, soil thickness, slope, soil organic matter, available sulfur, available copper, dehydrogenase, and available zinc were selected as the minimum data set (MDS). The SQ index (SQI) showed that three classes for soil quality among the eight P. fortunei plantations ranged from 0.48 to 0.88 and these were correlated with standing volume (p?<?0.05).Conclusions
From the results, we concluded that selected MDS indicators can describe the soil fertility quality of P. fortunei plantations, and that the relationship between SQI and standing volume has a biological significance. P. fortunei plantations intercropped with Camellia oleifera, orange trees, and Cunninghamia lanceolata (Lamb.) caused a deterioration in SQ, but intercropping oilseed rape and pure P. fortunei plantations produced an improvement in SQ.12.
Zhenghui Cui Hongwei Fang Lei Huang Ke Ni Danny Reible 《Journal of Soils and Sediments》2017,17(12):2887-2898
Purpose
Adsorptive interaction at the solid-water interface plays an important role in the fate and behavior of phosphorus (P) in rivers and lakes and the resulting eutrophication. This study aims to investigate the contributions of heterogeneous morphology to P adsorption onto mineral particles.Materials and methods
The dominant minerals in Yellow River sediment, quartz, k-feldspar, and calcite are investigated with adsorption experiments and microscopic examinations. Taylor expansion is applied to quantitatively characterize the heterogeneous surface morphology.Results and discussion
The results reveal that locally concave or convex micro-morphology characterized by the second derivative term of the Taylor expansion, F 2, can be related to adsorption capacity due to its effect on surface-charge density and distribution. The distribution of adsorbed P as a function of F 2 was determined for selected particles composed of each of the pure minerals and was fit to a Weibull distribution. Each mineral was characterized by F 2a , the weighted average value of F 2, and Weibull distribution factors, and correlated with sorption isotherms. The developed relationships were used to accurately predict adsorption onto individual particles as well as pure mineral samples.Conclusions
Mineral particles have complex surface morphology, which affects the interface P adsorption. Micro-morphological characterization of F 2 and F 2a can be used to predict adsorption onto the pure minerals, and this study provides physical basis for predicting adsorption on sediment particles composed of these minerals.13.
Yuzhe Wang Lianwei Zhang Hong Yang Guijun Yan Zhihong Xu Chengrong Chen Dongke Zhang 《Journal of Soils and Sediments》2016,16(3):801-810
Purpose
Biochar has been suggested as a soil conditioner to improve soil fertility and crop productivity while simultaneously mitigate global climate change by storing carbon in the soil. This study investigated the effect of pine (Pinus radiata) biochar application on soil water availability, nitrogen (N) and carbon (C) pools and growth of C3 and C4 plants.Materials and methods
In a glasshouse pot trial, a pine biochar (untreated) and nutrient-enriched pine biochar were applied to a market garden soil with C3 (Spinacia oleracea L.) and C4 (Amaranthus paniculatus L.) plants at rates of 0, 1.0, 2.0, and 4.0 % (w/w). Plant biomass, soil pH, moisture content, water holding capacity (WHC), hot water extractable organic C (HWEOC), and total N (HWETN), total C and N, and their isotope compositions (δ 13C and δ 15N) of soils and plants were measured at the end of the experimentation.Results and discussion
The soil moisture content increased while plant biomass decreased with increasing untreated biochar application rates. The addition of nutrient-enriched biochar significantly improved plant biomass in comparison to the untreated biochar addition at most application rates. Biochar application also increased the levels of labile organic C and N pools as indicated by HWEOC and HWETN.Conclusions
The results suggested that the addition of pine biochar significantly improved soil water availability but not plant growth. The application of nutrient-enriched pine biochar demonstrated that the growth of C3 and C4 plants was governed by biochar nutrient availability rather than its water holding capacity under the pot trial condition.14.
Jose Ramón Rico Hernández Ignacio Gómez-Lucas Jose Navarro-Pedreño Manuel M. Jordán Jaume Bech Victor M. Nieto Asencio Noemi Portell Iñiguez 《Journal of Soils and Sediments》2018,18(6):2172-2178
Purpose
This article analyzed the survival of Escherichia coli, total coliforms, and Salmonella spp. in a soil amended with urban sewage sludge due to its potential use in soil rehabilitation and to the risk of microbial pollution.Materials and methods
The survival of E. coli, total coliforms, and Salmonella spp. was determined in a soil amended with different doses of four different urban sewage sludge based on equivalent nitrogen fertilization of 0, 85, 170, and 340 kg N/ha. After the topsoil/sludge mixtures were made, they were wet to 18% moisture and analyzed for 2 months to determine the presence of bacteria, and then again after 1 year.Results and discussion
The results indicate that the presence of microorganisms was strongly conditioned by the type of biosolid and the dose applied. Soil moisture diminished as the experiment progressed and seemed to play a role in controlling the presence of the bacteria.Conclusions
The initial concentrations of bacteria depend on the sewage sludge treatment. The evolution of E. coli had a similar trend as total coliforms, and Salmonella spp. was absent after 8 weeks although a positive presence was detected in some soils after a year. As a conclusion, long periods of time reduce the risk from the presence of pathogens in soils, and the persistence may be closely related to the treatment of sewage sludge and the initial amount of microorganisms in the sewage sludge.15.
Purpose
The low conductivity of sediments for mass and electron transport is the most severe limiting factor in sediment microbial fuel cells (SMFCs), so that sediment ameliorations yielded more remarkable effects than electrode improvements. The objective of this research was to enhance the electricity generation of SMFCs with amendments of biochar to freshwater sediments for conductivity enhancement.Materials and methods
Laboratory-scale SMFCs were constructed and biochars were produced from coconut shells at different temperatures. Variations in the power output, electrode potential, internal resistance, total organic carbon (TOC) content, and microbial communities were measured.Results and discussion
Amending with biochar reduced the charge transfer resistances of SMFCs and enriched the Firmicutes (mainly Fusibacter sp.) in the sediment, which improved the SMFC power generation by two- to tenfold and enhanced the TOC removal rate by 1.7- to fourfold relative to those without the amendment.Conclusions
The results suggested that biochar amendment is a promising strategy to enhance SMFC power production, and the electrical conductivity of biochar should be considered important when interpreting the impact biochar has on the electrical performance of soil or freshwater sediment MFCs.16.
Jianqing Tian Chi Shu Huai Chen Yuchen Qiao Gang Yang Wan Xiong Lin Wang Jingzu Sun Xingzhong Liu 《Journal of Soils and Sediments》2015,15(1):179-188
Purpose
Understanding how archaeal communities are affected by water-table drawdown is essential for predicting soil functional responses to future climate change and the consequences of the responses on the soil carbon cycle.Material and methods
We investigated the effect of water-table drawdown, warming, drought, and combinations thereof on archaeal communities using terminal restriction fragment length polymorphism (T-RFLP) and quantitative PCR.Results and discussion
Methanosarcinales, Methanosaeta, Methanomicrobiales, Methanobacteriales, uncultured Rice Cluster II (RC-II), and uncultured Crenarchaeota were detected. Water-table drawdown and drought exhibited significant effects on the archaeal communities. When the water table was at or above 10 cm, the archaeal abundance at 10 cm remained high (approximately 109 cells per gram dry soil), whereas the archaeal abundance at 10 cm was reduced to approximately 108 cells per gram dry soil where the water table was lowered to 20 cm or below. When the water table kept constant, warming caused a significant reduction in the archaeal abundance, whereas drought only caused a decrease in archaeal abundance when the water table was higher than ?20 cm.Conclusions
Results suggest that changes in water table may directly impact archaeal community abundance and assemblage which can in turn influence methane emissions, potentially on a large scale. Our results also indicate that archaeal communities response to water-table drawdowns that are dependent on the initial ecohydrology.17.
Armando Cavalcante Franco Dias Francisco Dini-Andreote Rodrigo Gouvêa Taketani Siu Mui Tsai João Lúcio Azevedo Itamar Soares de Melo Fernando Dini Andreote 《Journal of Soils and Sediments》2011,11(8):1466-1476
Purpose
This study evaluates the presence and diversity of 16S rRNA (rrs) and amoA genes from archaea in three mangrove sediments under different stages of preservation (one pristine mangrove, one affected by anthropogenic activity, and another contaminated by an oil spill) in the state of São Paulo (Brazil).Materials and methods
A combination of DGGE, coupled with ordination analysis, and clone libraries of both targeted genes (rrs and amoA) was used to infer the diversity and phylogeny of archaeal communities in the mangrove analyzed samples.Results and discussion
The DGGE combined with multivariate analysis revealed, based on the ribosomal gene, differences in archaeal communities according to environmental parameters such as mangrove location, anthropogenic activity, and oil contamination. The profiles based on the amoA gene were more similar than those obtained for the gene rrs, with the only difference statistically observed for the community found in the mangrove under anthropogenic pressure. Furthermore, phylogenetic analysis revealed most archaeal groups affiliated to sequences belonging to the Thaumarchaeota (53.1%, 24 OTUs) and Euryarchaeota (29.6%, 14 OTUs) phyla, in addition to 14 sequences affiliated to an unclassified Archaea (16.1%, 8 OTUs). Concerning the analysis of the amoA gene, mangroves harbored sequences affiliated with those previously described in water column and soil/sediment samples, besides two possible clusters specifically found in mangroves.Conclusions
The findings are that the mangroves act as a reservoir for archaeal diversity, are possibly involved in nitrogen transformation in this ecosystem, and are affected by distinct pressures caused by anthropogenic activities.18.
Xiuzhen Shi Hang-Wei Hu Kevin Kelly Deli Chen Ji-Zheng He Helen Suter 《Journal of Soils and Sediments》2017,17(4):974-984
Purpose
The nitrification inhibitor 3,4-dimethylpyrazol-phosphate (DMPP) and the urease inhibitor N-(n-butyl) thiophosphoric triamide (nBTPT) can mitigate N losses through reducing nitrification and ammonia volatilization, respectively. However, the impact of repeated applications of these inhibitors on nitrogen cycling microorganisms is not well documented. This study aimed to investigate the changes in the abundance and community structure of the functional microorganisms involved in nitrification and denitrification in Australian pasture soils after repeated applications of DMPP and nBTPT.Materials and methods
Soil was collected in autumn and spring, 2014 from two pasture sites where control, urea, urea ammonium nitrate, and urea-coated inhibitors had been repeatedly applied over 2 year. Soil samples were analyzed to determine the potential nitrification rates (PNRs), the abundances of amoA, narG, nirK and bacterial 16S rRNA genes, and the community structure of ammonia oxidizers.Results and discussion
Two years of urea application resulted in a significantly lower soil pH at Terang and a significant decrease in total bacterial 16S rRNA gene abundance at Glenormiston and led to significantly higher PNRs and abundances of ammonia oxidizers compared to the control. Amendment with either DMPP or nBTPT significantly decreased PNRs and the abundance of amoA and narG genes. However, there was no fertilizer- or inhibitor-induced change in the community structure of ammonia oxidizers.Conclusions
These results suggest that there were inhibitory effects of DMPP and nBTPT on the functional groups mediating nitrification and denitrification, while no significant impact on the community structure of ammonia oxidizers was observed. The application of nitrification or urease inhibitor appears to be an effective approach targeting specific microbial groups with minimal effects on soil pH and the total bacterial abundance.19.
Pernilla Carlsson Jaromír Literák Ladislav Dušek Jakub Hofman Thomas D. Bucheli Jana Klánová 《Journal of Soils and Sediments》2016,16(6):1718-1726
Purpose
The scope of this article was to investigate the spatial and temporal variability of enantiomeric fractions (EFs) of persistent organic pollutants (POPs) in soil compared to the uncertainty of the analytical data.Materials and methods
Soil samples were taken with high spatial resolution at two sites in Czech Republic in 2008 to investigate variability on a small spatial scale. In addition, composite soil samples were taken from ten sites in 2005 and 2008 to investigate temporal variations. All samples were analysed for a suite of soil properties as well as concentrations and EFs of polychlorinated biphenyl (PCB) -95, PCB-132 and PCB-149; α-hexachlorocyclohexane (HCH); o,p′-dichlorodiphenyltrichloroethane (DDT); and o,p′-dichlorodiphenyldichloroethane (DDD).Results and discussion
Median EFs of PCB-95 and PCB-149, α-HCH, o,p′-DDT and o,p′-DDD did not change significantly on the sites sampled in 2005 and again in 2008, while PCB-132 changed from EF?=?0.38 to EF?=?0.53. The sampling methodology is therefore very important, and composite samples will not be the best option if enantioselective degradation processes are investigated. Non-racemic EFs of POPs in the subsampled sites in 2008 were correlated to soil parameters, such as total organic carbon (TOC), total nitrogen and humic acids. These parameters are site specific and might vary on a small scale. This can explain why certain soil parameters are reported as significantly correlated with non-racemic EFs of chiral POPs in some studies, but not always in other similar studies.Conclusions
While composite samples may still represent the overall prevailing EF range, they are not ideally suited to study enantiomeric degradation processes, which are taking place at a relative small scale, depending on the heterogeneity of soil parameters such as TOC, total organic nitrogen (TON) and humic acids.20.