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1.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2883-2891, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529862

RESUMO

To provide theoretical basis for management of Pinus sylvestris var. mongolica mixed plantation, the variation of soil carbon, nitrogen and phosphorus stoichiometry in different P. sylvestris var. mongolica belt-mixed plantations were explored. Taking the monoculture plantation as control, soil samples were collected at the distance of 0, 1, 2, 3, and 4 m from the center point in P. sylvestris var. mongolica and Ulmus pumila mixed plantation and P. sylvestris var. mongolica and Maackia amurensis mixed plantation along the two directions of P. sylvestris var. mongolica and its associated species in different soil layers. Contents and stoichiometric ratios of soil organic C, total N, total P, available N, available P were analyzed. The results showed that soil organic C, total N, and available N in P. sylvestris var. mongolica mixed plantations were higher than those in pure plantation. The soil organic C, total N contents, C/N and C/P in deep soil layers were increased under P. sylvestris var. mongolica and U. pumila mixed plantation. The soil N content increased but P content decreased in P. sylvestris var. mongolica and M. amurensis mixed plantation. With the increases of distance from the center of mixed plantation, soil C/N firstly increased and then decreased, while soil total P and available P contents decreased and N/P increased in P. sylvestris var. mongolica belt. Soil C/N decreased and available P contents firstly increased and then decreased with the increases of distance from the center in U. pumila belt of P. sylvestris var. mongolica and U. pumila mixed plantation. Soil total N content firstly decreased and then increased in P. sylvestris var. mongolica belt, but it firstly increased and then decreased in M. amurensis belt of P. sylvestris var. mongolica and M. amurensis mixed plantation. P. sylvestris var. mongolica mixed plantation could improve soil C and N stocks compared with pure plantation. The best mixed mode was P. sylvestris var. mongolica and U. pumila mixed by one row, as well as P. sylvestris var. mongolica and M. amurensis mixed in two rows.


Assuntos
Florestas , Nitrogênio/análise , Fósforo/análise , Pinus sylvestris , Pinus , Carbono , China , Solo/química
2.
Ying Yong Sheng Tai Xue Bao ; 30(9): 2999-3009, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529875

RESUMO

Two typical soil profiles of sand dune (mixed sandy loam with sandy soil; uniform sandy soil) were selected from the arid region on the edge of the Badain Jaran desert to analyze soil physical characteristics. The effects of soil physical characteristics on capillary rise were monitored and simulated. The relationship between two typical soil profiles of sand dune and capillary rise were investigated to reveal the interactive processes among groundwater, capillary water, and soil water. Results showed that capillary rise was mainly affected by soil bulk density and soil clay content in the arid-desert area. The capillary rise could reach to 152 cm above shallow layer in the profile of mixed sandy loam with sandy soils, and 120 cm in the profile of sandy soil, respectively. Soil water distribution driven by the capillary rise was more uniform in the profile of sandy soil. Soil water content showed a diminishing trend from the groundwater to the maximum distance of capillary rise. In contrast, soil water distribution was markedly varied in the profile of mixed sandy loam with sandy soil. The process of capillary movement could be well simulated with Hydrus-3D model. Soil structure above the groundwater was the critical factor, which could affect the capillary rise and soil water distribution. However, the effects of soil in-season evaporation and plant root uptake on capillary rise movement need to be explored in further studies.


Assuntos
Água Subterrânea/química , Solo/química , Clima Desértico , Modelos Químicos , Estações do Ano , Água
3.
Ying Yong Sheng Tai Xue Bao ; 30(9): 3019-3027, 2019 Sep.
Artigo em Chinês | MEDLINE | ID: mdl-31529877

RESUMO

We examined the role of photosynthesis in regulating soil CO2 emission under nitrogen enrichment in Keerqin sandy grassland. Results showed that nitrogen (N) application could affect soil respiration rate by altering the allocation of photosynthetic products to the belowground. Gross ecosystem photosynthesis rate (GEP) was positively correlated with soil respiration rate (Rs). Nitrogen application reduced slope of the fitting function from 0.236 to 0.161, with the equation intercept difference (0.51 µmol·m-2·s-1) being similar to the nighttime soil respiration rate increment (0.52 µmol·m-2·s-1). From May to October, the difference of photosynthetic rate (differential ratio) caused by nitrogen application was significantly correlated with that of soil respiration (differential ratio). Results from partial correlation confirmed the essential role of photosynthetic rate difference (ΔGEP) in driving soil respiration rate difference (ΔRs) caused by nitrogen application. In the nighttime, soil respiration rate was affected by the aboveground vegetation activities in daytime. The daily mean GEP was an important factor affecting the nighttime soil respiration rate difference (ΔRs) (P<0.01). Photosynthesis, rather than soil temperature, was the main factor affecting soil respiration rate difference (ΔRs) under nitrogen application. Thus, the role of photosynthetic assimilation-regulating may provide a novel supplement for elucidating the responses of soil respiration to nitrogen enrichment.


Assuntos
Pradaria , Nitrogênio , Fotossíntese , Solo/química , Dióxido de Carbono , Ecossistema , Estações do Ano
4.
J Environ Sci (China) ; 85: 66-73, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471032

RESUMO

Arsenic (As) mobilization in soils is a fundamental step controlling its transport and fate, especially in the presence of the co-existing components. In this study, the effect of two commonly used herbicides, glyphosate (PMG) and dicamba, and two competing ions including phosphate and humic acid, on As desorption and release was investigated using batch and column experiments. The batch kinetics results showed that As desorption in the presence of competing factors conformed to the pseudo-second order kinetics at pH range of 5-9. The impact of phosphate on desorption was greatest, followed by PMG. The competitive effect of dicamba and humic acid was at the same level with electrolyte solution. In situ flow cell ATR-FTIR analysis was performed to explore the mechanism of phosphate and PMG impact on As mobilization. The results showed that PMG promoted As(III) desorption by competiting for available adsorption sites with no change in As(III) complexing structure. On the other hand, phophate changed As(III) surface complexes from bidentate to monodentate structures, exhibiting the most siginficant effect on As(III) desorption. As(V) surface complexes remained unchanged in the presence of PMG and phosphate, implying that the competitive effect for As(V) desorption was primarily determined by the available adsorption sites. Long-term (10 days) soil column experiments suggested that the effect of humic acid on As mobilization became pronounced from 3 days (18 PVs). The insights of this study help us understand the transport and fate of As due to herbicides application.


Assuntos
Arsênico/química , Herbicidas/química , Poluentes do Solo/química , Adsorção , Substâncias Húmicas , Cinética , Solo/química
5.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2531-2540, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418175

RESUMO

Soil salinization is a global problem. Afforestation is a major improvement practice for desert saline-alkali land. To examine ecological improvement effects and spatial distribution of soil moisture and salinity in Tamarix ramosissima plantation with the age of 10 years in desert saline-alkali land, soil moisture and salt content between rows and under shrubs with row distance of 2, 4, 6, and 8 m were measured. The structural equation model was used to quantify the effects of soil water and salt changes on plant growth. The results indicated that soluble salt in shallow soil (0-40 cm) of T. ramosissima plantation was significantly lower than that outside the plantation, but soil moisture under shrubs was higher than that between rows. Among different row distances, the maximum values of height and canopy size of T. ramosissima and coverage and biomass of vegetation under the shrubs were found in row distance of 6 m. The enrichment degree of soil cations around taproot was in order of Na+>K+>Ca2+>Mg2+ and anions were enriched with Cl->HCO3->SO42-. There were five kinds of salts in soil, with MgSO4 being the most abundant, followed by CaCl2, NaCl and MgCl2, and the lowest being KHCO3. Soil moisture had the strongest effects on vegetation, followed by soil salinity, and the lowest was soil pH, with values of 50.6%,29.5% and 19.9%, respectively.


Assuntos
Solo/química , Tamaricaceae , Agricultura , Álcalis , China , Clima , Meio Ambiente
6.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2549-2557, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418177

RESUMO

We measured soil water and salt distribution characteristics at 0-40 cm soil depth in a silvopastoral system of Fraxinus chinensis and Robinia pseudoacacia mixed forest × Medicago sativa, which is located in Land Use Scientific Observation Field Base of Ministry of Land and Resource in Wudi, Shandong Province, China. The moving split-window technique was used to analyze the internal-system edge effect. The results showed that both soil water and salt contents in this system heterogeneously distributed in the horizontal direction. The variation of soil water was greater and that of soil salt contents was the smaller when closer to the soil surface. With the mixed forest tree row as the boundary line, the contents of soil water and salt on both sides showed similar change trend. With the decreases of distance to the tree row, soil water content reduced first and then increased but the salt contents had a stable fluctuation at 0-10 cm soil layer. Soil water content showed a trend of decrease-flat-decrease but the salt contents first enhanced and then reduced at 10-20 cm soil layer, respectively. At the deeper soil layer (20-40 cm), the water content fluctuated stably but the salt content continued increasing. Both the contents of soil water and salt in the vertical direction increased significantly with soil depth. Except HCO3- and K+, there was a similar change trend between ions and total salt content in the soil of silvopastoral system, and the correlation between these ions and total salt content was Na+>Cl->SO42->Mg2+>Ca2+. Based on the technique of moving split-window, the edge effect zone of soil water in the silvopastoral system was 2.5 m from the east side of the tree row to 2 m from the west side. Soil salinity in the silvopastoral system was mainly affected by the tree row within the range of 1.0 m, and by both of the tree row and M. sativa within the range of 1.0-3.0 m.


Assuntos
Ecossistema , Rios , Solo/química , China , Salinidade , Cloreto de Sódio , Água
7.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2558-2566, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418178

RESUMO

We explored the stoichiometric characteristic of Artemisia sacrorum communities and its correlation with soil characters by considering the aspect and slope position, and variation of soil nutrient in Yangqingchuan catchment of Wuqi. Our results showed that total carbon, total nitrogen, total phosphorus contents and C:N ratio in A. sacrorum (both shoot and root) in the top of hillock>sunny slope>semi-shady slope>shady slope. The C:P ratio in shoot and the N:P ratio in root decreased consistently. The N:P ratio in shoot and the C:P ratio in root decreased first and then increased. While the total nitrogen and total phosphorus in shoot, and the organic carbon in root increased first and then decreased with the decreases of slope position, the C:N ratio and N:P ratio in shoot decreased first and then increased. The stoichiometric characteristic of A. sacrorum communities was positively correlated with the soil stoichiometric characteristics. However, the C:N ratio, C:P ratio and N:P ratio of A. sacrorum and the total phosphorus of root were negatively correlated to corresponding soil indices. The correlation between shoot nutrition and soil was greater than that between soil and root nutrition. In conclusion, middle position of shady slope was optimal for the growth of A. sacrorum. The stoichiometric characteristics of plants were significantly correlated with soil nutrient condition. Aspect and slope position had a significant effect on the stoichiometric cha-racteristics of A. sacrorum community and soil. Proper A. sacrorum community could help restore soil nutrition.


Assuntos
Artemisia/fisiologia , Solo/química , China , Nitrogênio , Fósforo
8.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2567-2574, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418179

RESUMO

The study aimed to reveal the cumulative effects and stability characteristics of soil organic carbon (SOC) during forest development at the Mu Us sandy land, China. Using space for time substitution, surface soil samples were collected from semi-fixed sandy lands and restored arbor and shrub lands with the ages of 22, 32 and 53 years in the Yulin sand control region in Northern Shaanxi Province. The content of total organic carbon (TOC), oxidizable labile organic carbon, and resistant carbon and the characteristics of mineralized carbon emission and decomposition ratio were analyzed. The results showed that the increment of TOC for 22 to 53 years shrub and arbor lands from resistant carbon were 3.5-6.2 g·kg-1 and 3.2-7.7 g·kg-1, and from oxidized labile carbon were 2.8-3.4 g·kg-1 and 1.3-2.8 g·kg-1, respectively, compared with semi-fixed sand land. The ratio of soil oxidizable labile carbon in shrub land and arbor land were stable and maintained at 37.0% and 26.8%, respectively. However, the ratio decreased to 25.7% and 17.4% after incubated at a constant temperature for 60 days. The mineralization rate of shrub and arbor lands with 22-53 years was not significant at the ending of soil incubation. Carbon losses from oxidized liable carbon were 76.9%-98.7%, and only 1.3%-23.5% from resistant carbon in all sand-fixing forest plots. Compared with the maximum carbon emission rate, the soil cumulative carbon release exhibited a higher correlation with soil enzyme activities of ß-glucosidase and dehydrogenase, but the enzyme activities did not change from 32-53 years. In conclusion, SOC pool showed stable characteristics of lower emission and higher sequestration with the increases of sand-fixing forest stand age. The carbon fixation effect of arbor sand-fixing forest was better than that of shrub sand-fixing forest.


Assuntos
Carbono/análise , Florestas , Solo/química , Sequestro de Carbono , China
9.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2607-2613, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418184

RESUMO

Using Granier-type thermal dissipation probes (TDP), we measured stem xylem sap flow of the natural dominant species Quercus liaotungensis and a reforestation species Robinia pseudoacacia from July to September in 2016 in the semiarid loess hilly region. Meteorological factors and soil water content were simultaneously monitored during the study period. Using cross-correlation analysis, time lag between diurnal patterns of sap flux density and vapor pressure deficit (VPD) was quantitatively estimated. Differences in the time lag between the two species and possible influence by different diameter classes and soil water contents were analyzed. The results showed that the diurnal courses of sap flux density were similar to those of meteorological factors, with daily peaks ear-lier than VPD. The peak of VPD lagged behind the sap flux densities of Q. liaotungensis and R. pseudoacacia 118.2 min and 39.5 min, respectively. The peak of PAR lagged behind the sap flux density of Q. liaotungensis 12.4 min, but was 68.5 min ahead of that for R. pseudoacacia. Time lag between sap flux density and VPD significantly varied between tree species and was affected by soil water content. Those during higher soil water content period were about 32.2 min and 68.2 min longer than those during the period with lower soil water content for the two species, respectively. There was no correlation between time lag and tree diameter classes. The time lag between VPD and sap flux density for R. pseudoacacia was about 21.4 min longer in smaller diameter trees than in larger trees, which was significantly different under the lower soil water content. Our results suggested that the time lag effect between VPD and sap flux densities in the two species reflected their sensitivities to driving factors of transpiration, and that higher soil water content was favorable to sap flux density reaching its peak early. The lower soil water content might lead to lower sensitivity of the trees to meteorological factors. R. pseudoacacia was more sensitive to changes of soil water content.


Assuntos
Transpiração Vegetal/fisiologia , Quercus/fisiologia , Robinia/fisiologia , China , Solo/química , Árvores , Água/análise
10.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2737-2745, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418199

RESUMO

To investigate the changes of Zn availability and transformation in calcareous soil, orga-nic materials (maize straw, biofertilizer, fulvic acids, and chicken manure) were thoroughly mixed with the soils amended with Zn fertilizer in the nylon net bags and buried in a field. Results showed that compared with control (neither Zn nor organic materials), Zn fertilizer alone and combined addition with organic materials significantly increased soil total Zn concentration (7.2%-13.8%) and DTPA-Zn concentration (2.1-2.8 folds). For the Zn amended treatments, the contributions of organic amendments to soil total Zn and DTPA-Zn concentration decreased in the order of chicken manure > biofertilizer > maize straw > fulvic acids. The highest conversion rate of exogenous Zn into DTPA-Zn occurred in the treatments with straw and biofertilizer. In comparison with single Zn application, combination of Zn fertilizer with organic materials increased soil organic matter and stimulated more Zn weakly bound to organic matter, enhanced mobility factor and reduced distribution index of Zn in soil. The differences in soil Zn availability and transformation among the combinations of Zn fertilizer and organic materials were likely linked to the inherent properties of organic materials such as maturity degree and Zn content. Considering the environment safety and cost reduction, combining Zn fertilizer and straw return was the best practice to enhance Zn availability in the Zn-deficient calcareous soil, although its contribution to Zn availability was less than the combination of biofertilizer or chicken manure with Zn fertilizer.


Assuntos
Fertilizantes , Poluentes do Solo , Zinco/química , Esterco , Solo/química
11.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2746-2756, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418200

RESUMO

To understand the effects of agricultural management activities on soil arbuscular mycorrhizal (AM) fungi diversity, the high-throughput sequencing based on Illumina MiSeq platform, and the fatty acids fingerprints were used to examine the effects of maize straw returning on soil arbuscular mycorrhizal fungi. The relationships between AM fungal community composition, AM fungal biomass and soil factors after maize straw returning were examined for four continuous years. A total of 2430 operational taxonomic units (OTUs) of AM fungi were classified into 10 genera and 143 species, respectively, which belonged to 1 phylum, 3 classes, 4 orders, 8 families. There was no significant difference in AM fungal community richness (Chaoles index and ACE index) and diversity (Shannon, Simpson diversity indices) in different treatments. Paraglomus and Glomus were dominant genera among all AM fungal communities. With the increase of the maize straw returned amounts, the abundance of Glomus reduced. Under the treatments of 3000 and 9000 kg·hm-2 straw returned, the abundance of Glomus and Acaulospora had significant differences with the control (0 kg·hm-2). Compared with the control, there were significant differences between Archaeospora, Paraglomus and Glomus in the treatment of 3000 kg·hm-2 straw returned. Results from non-metric multi-dimensional scale (NMDS) analysis showed that under 9000 and 12000 kg·hm-2 straw returning treatments, the difference between the ß diversity of soil AM fungi and the spatial distance of controls was farther apart than the other treatments. The effect of straw returning on the ß diversity of AM fungi was significant. The multivariate analysis results revealed the relationship of the spatial variation between the soil physicochemical properties and AM fungi richness and diversity could be explained at 82.8% cumulative variables. The total nitrogen and available nitrogen were the most important factors driving soil microbial communities biomass marked by PLFAs and AM fungal biomass (NLFAs). The continuous maize straw returning to the field changed the genera composition of AM fungi. With the increases of straw returning amounts, the specific species of AM fungi decreased and the similarity between AM fungi community composition decreased. Straw returning increased soil AM fungi biomass and its contribution to soil total microbial biomass.


Assuntos
Micobioma , Micorrizas , Microbiologia do Solo , Solo/química , Zea mays
12.
Ying Yong Sheng Tai Xue Bao ; 30(8): 2757-2766, 2019 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-31418201

RESUMO

Soil microbial community dynamics during the spring freezing-thawing period could affect carbon and nutrient cycling in the subsequent growing season. During spring soil freezing-thawing period, we monitored temporal dynamics of soil microbial community in different soil substrates for Larix gmelinii forest using phospholipid fatty acids (PLFAs) as biomarkers every 3-7 days. The results were as followed: 1) the total PLFAs content, the PLFAs content and relative abundance of each soil microbial group, the ratio of Gram-positive bacteria to Gram-negative bacteria (G+/G-), the ratio of saturated PLFAs to unsaturated PLFAs (S/NS) and the ratio of bacteria to total fungi (fungi + arbuscular mycorrhizal fungi) (B/F) all varied among sampling times; 2) soil total organic carbon (TOC) and nitrogen (TN) were the main factors affecting soil microbial community in the early stage of soil freezing-thawing period; soil moisture, TOC and TN were the main driving factors in the middle stage of soil freezing-thawing period; soil microbes were affected by soil tempera-ture, moisture, TOC, TN and C/N in the late stage of soil freezing-thawing period; 3) the total PLFAs content, the PLFAs content and relative abundance of each soil microbial group (except the relative abundance of bacteria), B/F, G+/G- and S/NS all showed significant difference between soil substrates, and soil TOC, TN and C/N were the key determination factors. Soil temperature, moisture, and nutrient availability were the main factors affecting soil microbial community during the spring soil freezing-thawing period, but the degree of influence varied with the freezing-thawing stages and microbial groups.


Assuntos
Larix , Microbiologia do Solo , Solo/química , Florestas , Congelamento , Nitrogênio , Estações do Ano
13.
Zoology (Jena) ; 135: 125689, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31383298

RESUMO

Heterorhabditis nematodes are parasites of a wide range of soil-dwelling insect species. Although these nematodes have been exploited as biological control agents since the last half of the 20th century, much research remains to be done to understand how these organisms function in agricultural and other ecosystems. In this study, we present some ecological traits of Heterorhabditis sonorensis, a natural parasite of the cicada Diceroprocta ornea, from the Sonoran Desert. Specifically, we evaluated its infectivity across a diverse panel of insect groups and assessed its fitness (infectivity and reproduction) considering different temperatures, and soil moisture levels. Three other Heterorhabditis species served as points of comparison for temperature and soil moisture assays. Host range experiments indicate that H. sonorensis, although isolated from seasonal cicada nymphs, is more virulent and reproductively fit in the lepidopteran hosts tested. This nematode has an optimum temperature range at 25-30 °C but can also successfully reproduce at temperatures ranging from 15 to 35 °C. Additionally, this nematode is adapted to a variety of soil moisture conditions with successful infections across the tested moisture range (3%-20%). Finally, we demonstrate that H. sonorensis infective juveniles have a high survival rate (over 80%) at various storage temperatures (10-25 °C) after 24 weeks of storage and remain infective as revealed by the post-storage infection assays.


Assuntos
Clima Desértico , Meio Ambiente , Nematoides , Animais , Hemípteros/parasitologia , Especificidade de Hospedeiro , Lepidópteros/parasitologia , Nematoides/fisiologia , Solo/química , Solo/parasitologia , Temperatura Ambiente
14.
J Microbiol ; 57(9): 717-724, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31452042

RESUMO

Salterns are hypersaline extreme environments with unique physicochemical properties such as a salinity gradient. Although the investigation of microbiota in salterns has focused on archaea and bacteria, diverse fungi also thrive in the brine and soil of salterns. Fungi isolated from salterns are represented by black yeasts (Hortaea werneckii, Phaeotheca triangularis, Aureobasidium pullulans, and Trimmatostroma salinum), Cladosporium, Aspergillus, and Penicillium species. Most studies on saltern-derived fungi gave attention to black yeasts and their physiological characteristics, including growth under various culture conditions. Since then, biochemical and molecular tools have been employed to explore adaptation of these fungi to salt stress. Genome databases of several fungi in salterns are now publicly available and being used to elucidate salt tolerance mechanisms and discover the target genes for agricultural and industrial applications. Notably, the number of enzymes and novel metabolites known to be produced by diverse saltern-derived fungi has increased significantly. Therefore, fungi in salterns are not only interesting and important subjects to study fungal biodiversity and adaptive mechanisms in extreme environments, but also valuable bioresources with potential for biotechnological applications.


Assuntos
Fungos/fisiologia , Sais/química , Cloreto de Sódio/metabolismo , Solo/química , Adaptação Fisiológica , Fungos/classificação , Fungos/genética , Fungos/isolamento & purificação , Tolerância ao Sal
15.
An Acad Bras Cienc ; 91(3): e20180334, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31411254

RESUMO

The aim of this study is to discuss the concentration distribution, composition and possible sources of trace metals and 13 PAHs in topsoils of the University campus, in the city of São Paulo, the largest city of South America. Mineralogy and granulometry of topsoils (0-10 cm) samples, were determined and As, Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Sb, V, Zn, Hg, Pt, Pd and PAHs concentrations were quantified in the bulk fraction. The average clay content of soils was 221±61.8 g kg-1 and total carbon was low (mean of 25 g kg-1). Concentrations of metals were generally lower than the reference value established by the São Paulo State Environmental Agency and other studies in the São Paulo urban area, except for Cd, Ni, Pb, Cr and Zn. The mean concentration of the sum of 13 PAHs was 0.33 mg kg-1 and fluorene, indeno(1,2,3-cd)pyrene, anthracene, pyrene and benzo(ghi)perylene were the most abundant compounds. PAHs and trace metals variability were constrained in PMF analysis and showed an association with exhaust and non-exhaust vehicular emissions. The results also pointed out a spatial pattern in the campus area related to traffic conditions and intensity and terrain slope.


Assuntos
Metais Pesados/análise , Hidrocarbonetos Policíclicos Aromáticos/análise , Solo/química , Oligoelementos/análise , Universidades , Brasil , Cidades , Monitoramento Ambiental , Humanos , Metais Pesados/química , Hidrocarbonetos Policíclicos Aromáticos/química , Medição de Risco , Análise Espacial , Oligoelementos/química , Poluição Relacionada com o Tráfego/análise , Emissões de Veículos/análise
16.
BMC Plant Biol ; 19(1): 306, 2019 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-31296169

RESUMO

BACKGROUND: Phosphorus (P) deficiency in soil is a worldwide issue and a major constraint on the production of sorghum, which is an important staple food, forage and energy crop. The depletion of P reserves and the increasing price of P fertilizer make fertilizer application impractical, especially in developing countries. Therefore, identifying sorghum accessions with low-P tolerance and understanding the underlying molecular basis for this tolerance will facilitate the breeding of P-efficient plants, thereby resolving the P crisis in sorghum farming. However, knowledge in these areas is very limited. RESULTS: The 29 sorghum accessions used in this study demonstrated great variability in their tolerance to low-P stress. The internal P content in the shoot was correlated with P tolerance. A low-P-tolerant accession and a low-P-sensitive accession were chosen for RNA-seq analysis to identify potential underlying molecular mechanisms. A total of 2089 candidate genes related to P starvation tolerance were revealed and found to be enriched in 11 pathways. Gene Ontology (GO) enrichment analyses showed that the candidate genes were associated with oxidoreductase activity. In addition, further study showed that malate affected the length of the primary root and the number of tips in sorghum suffering from low-P stress. CONCLUSIONS: Our results show that acquisition of P from soil contributes to low-P tolerance in different sorghum accessions; however, the underlying molecular mechanism is complicated. Plant hormone (including auxin, ethylene, jasmonic acid, salicylic acid and abscisic acid) signal transduction related genes and many transcriptional factors were found to be involved in low-P tolerance in sorghum. The identified accessions will be useful for breeding new sorghum varieties with enhanced P starvation tolerance.


Assuntos
Fósforo/deficiência , Reguladores de Crescimento de Planta/metabolismo , Transdução de Sinais/genética , Sorghum/genética , Grão Comestível/genética , Grão Comestível/fisiologia , Perfilação da Expressão Gênica , Solo/química , Sorghum/fisiologia
17.
J Agric Food Chem ; 67(29): 8107-8118, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31260291

RESUMO

Humic substances (HS) are vital to soil fertility and carbon sequestration. Using multiple cross-polarization/magic-angle spinning (multiCP/MAS) NMR combined with dipolar dephasing, we quantitatively characterized humic fractions, i.e., fulvic acid (FA), humic acid (HA), and humin (HM), isolated from two representative soils (upland and paddy soils) in China under six long-term (>20 years) fertilizer treatments. Results indicate that each humic fraction showed chemical distinction between the upland and paddy soils, especially with much greater aromaticity of upland HMs than of paddy HMs. Fertilizer treatment exerted greater influence on chemical natures of upland HS than of paddy HS, although the effect was less than that of soil type. Organic manure application especially decreased the percentages of aromatic C in the upland HAs and HMs compared with the control. We concluded that humic fractions responded in chemical nature to environmental conditions, i.e., soil type/cropping system/soil aeration and fertilizer treatments.


Assuntos
Substâncias Húmicas/análise , Espectroscopia de Ressonância Magnética/métodos , Solo/química , Carbono/análise , China , Fertilizantes/análise , Esterco/análise , Oryza/crescimento & desenvolvimento , Oryza/metabolismo
18.
J Agric Food Chem ; 67(29): 8130-8137, 2019 Jul 24.
Artigo em Inglês | MEDLINE | ID: mdl-31287295

RESUMO

Chlorantraniliprole (3-bromo-N-[4-chloro-2-methyl-6-(methylcarbamoyl)phenyl]-1-(3-chloro-2-pyridine-2-yl)-1H-pyrazole-5-carboxamide; CAP) was granted supplemental registration for use in rice cultivation in California through December, 2018. Previous work investigated the partitioning of CAP in California rice field soils; however, its degradation in soils under conditions relevant to California rice culture has not been investigated. The degradation of CAP in soils from two California rice fields was examined under aerobic and anaerobic conditions with varying salinity via microcosm experiments. Results indicate that soil properties governing bioavailability may have a greater influence on degradation than flooding practices or field salinization over a typical growing season. Differences between native and autoclaved soils (t1/2 = 59.0-100.2 and 78.5-171.7 days) suggest that biological processes were primarily responsible for CAP degradation; however, future work should be done to confirm specific biotic processes as well as to elucidate abiotic processes, such as degradation via manganese oxides and formation of nonextractable residues, which may contribute to its dissipation.


Assuntos
Inseticidas/química , Oryza/crescimento & desenvolvimento , Poluentes do Solo/química , Solo/química , ortoaminobenzoatos/química , Agricultura , California , Inundações , Cinética
19.
World J Microbiol Biotechnol ; 35(8): 117, 2019 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-31332532

RESUMO

Iron- and sulfur-oxidizing bacteria inhabiting rice rhizoplane play a significant role on arsenic biogeochemistry in flooded rice paddies, influencing arsenic translocation to rice grains. In the present study, the selective pressure of arsenic species on these microbial populations was evaluated. Rice roots from continuously flooded plants were incubated in iron sulfide (FeS) gradient tubes and exposed to either arsenate or arsenite. The biomass developed in the visible iron-oxidation band of the enrichments was analyzed by Scanning Electron Microscopy and Energy-Dispersive Spectroscopy (SEM-EDS) and the bacterial communities were characterized by 16S rRNA gene sequencing. Different Proteobacteria communities were selected depending on exposure to arsenate and arsenite. Arsenate addition favored the versatile iron-oxidizers Dechloromonas and Azospira, associated to putative iron (hydr)oxide crystals. Arsenite exposure decreased the diversity in the enrichments, with the development of the sulfur-oxidizer Thiobacillus thioparus, likely growing on sulfide released by FeS. Whereas sulfur-oxidizers were observed in all treatments, iron-oxidizers disappeared when exposed to arsenite. These results reveal a strong impact of different inorganic arsenics on rhizospheric iron-oxidizers as well as a crucial role of sulfur-oxidizing bacteria in establishing rice rhizosphere communities under arsenic pressure.


Assuntos
Arsênico/metabolismo , DNA Bacteriano/isolamento & purificação , Oryza/efeitos dos fármacos , Oryza/microbiologia , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/microbiologia , Arseniatos/metabolismo , Arsenitos/metabolismo , DNA Bacteriano/genética , Ferro/metabolismo , Oxirredução , Proteobactérias/efeitos dos fármacos , Proteobactérias/isolamento & purificação , Proteobactérias/metabolismo , RNA Ribossômico 16S/genética , RNA Ribossômico 16S/isolamento & purificação , Solo/química , Microbiologia do Solo , Poluentes do Solo/metabolismo , Enxofre/metabolismo
20.
Ying Yong Sheng Tai Xue Bao ; 30(6): 1840-1846, 2019 Jun.
Artigo em Chinês | MEDLINE | ID: mdl-31257754

RESUMO

We used two types of soil with different physicochemical properties (loam and sand), oven-dried them, and then added the known isotopic composition mineral water that was reference water to compose the soil-water mixture with different soil water contents (loam: 0.15, 0.20, 0.30 g·g-1; sand: 0.10 g·g-1). After that, we set up different equilibrium time (loam: 3, 6, 12, 24, 48, 72, 96 h; sand: 96 h) to ensure that the dry soil particles were well mixed with the added water. The soil water was extracted by mechanical centrifugation and cryogenic vacuum extraction after equilibrium, and their isotope composition was analyzed. Results showed that the isotopic values of soil water extracted by mechanical centrifugation method had no significant difference in same water content with different equilibration times, but were more enriched compared with the reference water isotopic value. The maximum enrichment for hydrogen and oxygen isotope was 7.38‰ and 1.24‰, respectively. In contrast, cryogenic vacuum extraction method resulted in more depleted soil water isotopes than reference water, with the maximum depletion for hydrogen and oxygen isotope being 6.27‰ and 1.03‰, respectively. Moreover, the degree of depletion increased with the increases of equilibrium time (less than 24 h) at low water content, and became stable after 24 h. With the increases of soil water content, the isotopic composition of the extracted soil water was less affected by the two extraction methods. The water isotope value of loam that had high clay content, was more sensitive to the extraction method than the sandy soil that had low clay content. The difference of isotopic composition caused by extraction methods did not affect the plant water source segmentation.


Assuntos
Fracionamento Químico/métodos , Plantas/química , Solo/química , Água , Deutério , Isótopos de Oxigênio/análise
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