TP Content Research Articles

Vertical distribution and seasonal variation of nitrogen, phosphorus elements in Spartina alterniflora wetland of Jiaozhou Bay, Shandong, China

In order to study the vertical distribution and the seasonal variation of N and P in Spartina alterniflora wetland of Jiaozhou Bay, soil samples in S. alterniflora wetland and bare flat in April, July, September, October, November and December 2015 were collected, and TN, NH4+-N, TP, AP, TOC, pH, salinity and water content were tested. The average values of soil TN, NH4+-N, TP and AP contents in S. alterniflora wetland were 0.396 g·kg-1, 12.14 mg·kg-1, 0.385 g·kg-1 and 16.52 mg·kg-1 respectively, while those in bare flat were 0.419 g·kg-1, 8.13 mg·kg-1, 0.423 g·kg-1 and 19.57 mg·kg-1 respectively. Generally, they decreased gradually with the increase of the soil depth (0-60 cm). The contents of N and P in S. alterniflora wetland had obvious variations with season. The maximum and minimum of soil TN contents in S. alterniflora wetland were in spring and autumn respectively, while the content of soil TN in bare flat decreased with the change of season. Compared with the bare flat, the content of TP in S. alterniflora wetland had the opposite trend with the change of season, while that of AP had the same trend. The contents of TN and TP were significantly positively related with TOC, while there was no significant correlation between them in the bare flat. N and P contents in S. alterniflora wetland and bare flat were obviously influenced by pH and salinity.

Evaluation of Pomegranate Pomace Supplemented with Different Levels of Polyethylene Glycol using In Vitro Gas Production Technique

The object of this study was to examine the chemical composition, including the tannin content of pomegranate pomace supplemented withdifferent levels of tannin-binding Agent (Polyethylene Glycol) and gas production amount using in vitro gas production technique. The treatment contained 0, 75, 150, 300 and 450mg PEG per each serum bottle, respectively. Approximately 300 mg of dried and ground (2mm) Pomegranate pomace were weighed and placed into serum bottles. CP, ADF, NDF, EE, ASH, TP and TT contents in pomegranate pomace were 8.7%, 27.6%, 32.3%, 1.7%, 9.2%, 5.4% and 4.6%, respectively. At the 2 h incubation times, the gas production amount of PP, PP + 75 mg PEG, PP + 150 mg PEG, PP + 300 mg PEG and PP + 450mg PEG were 29.83, 32.89, 23.26, 25.83 and 19.37 ml/g DM. At the first incubation times (2 and 4h), the PP + 75mg PEG treatments had the highest in vitro gas production amount within treatments (P<0.05). At all incubation times PP+75mg PEG treatment had the highest in vitro gas production amount within treatments (P<0.05). The addition of PEG at levels 75 and 450mg increased the in vitro gas production amount.

Long-term assessment at field scale of Floating Treatment Wetlands for improvement of water quality and provision of ecosystem services in a eutrophic urban pond.

Pollution of urban water bodies requires stringent control measures and the development of low-cost and highly efficient alternative technologies. In contrast to Constructed Wetlands, Floating Treatment Wetlands (FTWs) have the advantage of not requiring large surface of land since they operate in situ. However, there is limited information about their long-term evaluation while operating at field scale. The aim of this work was to assess the performance of FTWs using a combination of Pontederia sagittata and Cyperus papyrus for the improvement of the water quality and provision of ecosystem services of a eutrophic urban pond. The FTWs were built with low-cost material easy to acquire and to ensemble. Two FTWs (17.5m2 and 33m2) located in Pond 1 within a complex of 4 urban artificial ponds were evaluated for two years. They promoted an increase in the dissolved oxygen (D.O.) within a range of 15 to 67%, a removal of fecal coliforms in the range of 9 to 86% and a nitrate removal in the range of 9 to 76%. The plant productivity reached a maximum of 363gdmm-2d-1 in the FTW1 and 536gdmm-2d-1 in the FTW2 during the period March-June 2016. The TKN and the TP content in the plant were in the range of 18.3 to 28.1 and of 0.05 to 0.196gkg-1 dry matter, respectively. In conclusion, the tested FTWs have proved to be a very beneficial low-cost technology for the improvement of water quality and provision of ecosystem services.

Impact of aeration disturbances on endogenous phosphorus fractions and their algae growth potential from malodorous river sediment.

The present work assessed the impact of aeration disturbances on sediment-bound phosphorus fractions and their algae growth potential from a typical malodorous river. Phosphorus was sequentially extracted by a modified version of Hedley fractionation method. It was found that the mean contents of TP was 1476.1±60.3mg/kg, consisting mainly of dilute HCl-extractable P (52.6%) and NaOH-P (19.2%). The algae growth potential tests demonstrated that algae growth had varied P-level requirements for different P speciation and NaOH-P promoted algae growth remarkably and its promoting effect was positively related to its concentration. Additionally, intermittent overlying water aeration modes were recommended, and run 1 (7.0mg/L, 12h) was deemed as the optimized aerated mode in terms of its relatively low ecological risk and high P retention. It was noted that NaOH-P was most affected by aeration disturbance and exhibited marked increase with the elevated dissolved oxygen (DO) level whether for intermittent overlying water or sediment aeration. This research helps to gain improved understanding of the ecological risk on sediment P, and NaOH-P is recognized as one ecologically important P fraction in the sediments considering its relatively high proportion and bioavailability.

An evaluation of different soil washing solutions for remediating arsenic-contaminated soils

Soil washing is a promising way to remediate arsenic-contaminated soils. Most research has mostly focused on seeking efficient extractants for removing arsenic, but not concerned with any changes in soil properties when using this technique. In this study, the removal of arsenic from a heavily contaminated soil employing different washing solutions including H3PO4, NaOH and dithionite in EDTA was conducted. Subsequently, the changes in soil physicochemical properties and phytotoxicity of each washing technique were evaluated. After washing with 2 M H3PO4, 2 M NaOH or 0.1 M dithionite in 0.1 M EDTA, the soil samples’ arsenic content met the clean-up levels stipulated in China’s environmental regulations. H3PO4 washing decreased soil pH, Ca, Mg, Al, Fe, and Mn concentrations but increased TN and TP contents. NaOH washing increased soil pH but decreased soil TOC, TN and TP contents. Dithionite in EDTA washing reduced soil TOC, Ca, Mg, Al, Fe, Mn and TP contents. A drastic color change was observed when the soil sample was washed with H3PO4 or 0.1 M dithionite in 0.1 M EDTA. After adjusting the soil pH to neutral, wheat planted in the soil sample washed by NaOH evidenced the best growth of all three treated soil samples. These results will help with selecting the best washing solution when remediating arsenic-contaminated soils in future engineering applications.

The antioxidative and hepatoprotective effects comparison of Chinese angelica polysaccharide(CAP)and selenizing CAP (sCAP) in CCl4 induced hepatic injury mice

Chinese angelica polysaccharides (CAP) and selenizing CAP (sCAP) were prepared and identified through FTIR and SEM observation. Their antioxidant activities in vitro and hepatoprotective effects in vivo were compared by free radical-scavenging tests or with CCl4-induced hepatic injury model mice. The results showed that for DPPH radical, superoxide anion and hydroxyl radical, the scavenging capabilities of sCAP were significantly stronger than those of CAP. In hepatic injury model mice, sCAP could significantly reduce ALT, AST and ALP contents and raised TP content in serum, significantly reduce MDA and ROS contents and raised SOD and T-AOC activities in liver homogenate in comparison with CAP; obviously relieve the pathological changes of liver and significantly inhibit the expressions of p-ERK, p-JNK and p-p38 protein as compared with those in model control group. These results indicate that selenylation modification can enhance the antioxidant and hepatoprotective actions of Chinese angelica polysaccharide. A action mechanism of sCAP is suppressing the protein expression of MAPK signaling pathway.

Phragmites australis + Typha latifolia Community Enhanced the Enrichment of Nitrogen and Phosphorus in the Soil of Qin Lake Wetland.

Aquatic plants play an essential role and are effective in mitigating lake eutrophication by forming complex plant-soil system and retaining total nitrogen (TN) and phosphorus (TP) in soils to ultimately reduce their quantities in aquatic systems. Two main vegetation types (Phragmites australis community and P. australis + Typha latifolia community) of Qin Lake wetland were sampled in this study for the analysis of TN and TP contents and reserves in the wetland soils. The results showed that (1) the consumption effect of Qin Lake wetland on soluble N was much more significant than on soluble P. (2) The efficiency of TN enrichment in wetland soil was enhanced by vegetation covering of P. australis and T. latifolia. (3) Wetland soil P was consumed by P. australis community and this pattern was relieved with the introduction of T. latifolia. (4) According to the grey relativity analysis, the most intensive interaction between plants and soil occurred in summer. In addition, the exchange of N in soil-vegetation system primarily occurred in the 0–15 cm soil layer. Our results indicated that vegetation covering was essential to the enrichment of TN and TP, referring to the biology-related fixation in the wetland soil.

Beta-diversity and structuring forces of diatom communities in small lakes of the Carpathian Basin

Investigating the dynamics beyond the patterns (structure, diversity) of microbial communities at regional level in different spatial scales has been a developing area in ecology and studies on diatoms with such approach receive increasing scientific interest. In this study, phytobenthos samples were collected from 41 lakes (<7 km2) in the Carpathian Basin in August 2010 and physical and chemical parameters were also determined simultaneously. Our aim was to quantify the regional species pool (γ-diversity), the local species richness (α-diversity), the dissimilarity among diatom communities (β-diversity) and to assess whether β- diversity is supported by species replacement or richness differences (nestedness). Furthermore, we investigated the local contribution to β-diversity (LCBD) of our sampling sites and that which factors play a key role in establishment of β-diversity. In the study region, we experienced high γ- (a total of 302 diatom species) and α-diversity (average species richness of 45±13). The diatom community was characterised by high β-diversity (> 0.93 multiple-site Sorensen dissimilarity) which was explained mainly by species turnover. Although deterministic processes were more decisive based on null model analyses, stochasticity can also take part in community assembly. The degree of β-diversity (and thus assembly of communities, as well) was related significantly to the local environmental variables, especially to TP content and to the geographical distance between samplig sites. Samples from Kun-Feher-to, Pirtoi Nagy-to, Sarkany-to and Vadasa-to showed significant relative contribution to β-diversity. Cl- and HCO3 - content were determining factors for LCBD, whereas local species richness was related to HCO3 - and water temperature. Moreover, we found a decline in LCBD with the increase of species richness. The study was supported by the National Scientific Research Foundation (OTKA K81599), the Szechenyi 2020 under the EFOP-3.6.1-16-2016-00015 and the UNKP-17-3-IV-PE-5 New National Excellence Program of the Ministry of Human Capacities.

星云湖季节性水质变化及影响因素

依据实地监测数据，本文分别对旱季和雨季末星云湖水体在垂向和空间分布上的水质变化特征进行了分析，探讨了季节性水量变化对星云湖水质的影响。监测结果显示：星云湖丰水期水质空间差异较小，枯水期水质空间差异较大，主要表现在丰水期溶解氧含量高于枯水期。同时，丰水期水体的比电导明显高于枯水期。星云湖水体的pH值在8.9~9.4之间变化，且有枯水期高于丰水期的特征。在垂向上，星云湖丰水期水温、pH值与溶解氧含量具有相似变化趋势，整体上均随深度的增加而呈现下降的变化，这可能与浮游藻类的呼吸作用有关；丰水期水体中叶绿素含量在整个湖泊较低且趋于一致，而枯水期具有由表层向下增高的变化。营养盐分析结果显示，丰水期的总磷(TP)含量平均为0.43~0.48 mg/L，枯水期平均为0.29~0.39 mg/L；而丰水期的总氮(TN)含量平均为2.1557~2.5225 mg/L，枯水期1.9388~2.875 mg/L，指示丰水期河流物质输入作用明显增加，人类活动影响明显增强。计算分析结果显示，星云湖水体全湖全年为重富营养水平，且具有枯水期水质富营养水平南部 >中部 > 北部水体、底层 > 中层 > 表层水体、丰水期北部 > 南部 > 中部水体，中层 > 底层 > 表层水体的特点。认识这些特点及时空变化规律，对于有的放矢、高效的开展星云湖富营养化治理具有一定的指导作用。 Based on field monitoring data, the characteristics of water quality changes, in both vertical and spatial distributions in the end of dry and wet seasons in Xingyun Lake were analyzed. The monitoring data shows that the water temperature has seasonal changes and on the vertical profile, the water temperature almost always below 1 m in depth. In wet season, the lake water mixture condition enhanced, and the water quality shows slight changes in spatial pattern, but it displays a significant difference in dry season. In vertical profile, the pH value of lake water shows a high uniformity from the surface to 7 m in depth, with an average value of 8.9~9.4. And it shows that a higher value in wet than in dry season. The chlorophyll content in Xingyun Lake shows a weak seasonal change in wet season, but the content increases with the increasing of water depth in dry season. The dissolved oxygen content is higher in wet season than that in dry season. The SpCond is significantly higher in wet season than that in dry season. We found that the water temperature, pH value and dissolved oxygen content possess a similar change tendency in vertical profile. Our analysis results reveal that the average TP content in the wet season is 0.43~0.48 mg/L, while that in dry season is 0.29~0.39 mg/L. The average TN content is 2.16~2.52 mg/L in wet seasons, and 1.94~2.88 mg/L in dry seasons, showing the TP and TN input increased significantly in the wet season. The calculation results demonstrated that the whole lake possess a heavy nutrient level, and the nutrient level distribute a pattern of in the south > in the central > in the north, the bottom > the surface > the middle in dry season, and the north > the south > the central, the middle > the bottom > the surface in wet season.

Case study: characterization of source-separated blackwater and greywater in the ecological housing estate Lübeck “Flintenbreite” (Germany)

The objective of this paper is the characterization of grey- and blackwater from the housing estate “Flintenbreite” in Lubeck, Germany. The housing area “Flintenbreite” was selected for the investigation since its wastewater system has separate flows for grey- and blackwater. Although the knowledge on the characteristics of blackwater and greywater is essential for the design of treatment units, the data basis is still weak and design values are not available. In general greywater wastewater contains lower levels of organic matter and nutrients compared to domestic wastewater. The greywater loads for CODt, TNt and TPt found in Lubeck Flintenbreite were 45 g per capita and day (gpcd), 0.84 and 0.4 gpcd. The liquid greywater phase contained the majority of the daily loads. Around 5, 7 and 2.5% of the inhabitant-specific daily loads were found in the greywater solid phase. The mean concentrations of the organic blackwater parameters TOC, DOC and DIC were 15.06, 6.16 and 5.51 gcpd are much higher compared to municipal wastewater. Due to the fact that the TOC is about two times higher than the DOC, a direct correlation between dry residues and total organic carbon was proved. The TP content of 0.44 gcpd in blackwater is quite low. A high variability of the nutrient amounts during the yearly seasons is assumed, because the amount of phosphorous in blackwater was 1/3 higher in the summer season compared to the winter season. For the parameter TN, a high average concentration of 8.47 gpcd was found. High TN concentrations of more than 1 g/l are usually declared as critical for the anaerobic treatment process, but during 2 years of anaerobic digestion experiments no adverse effects of the anaerobic digestion were detected.

Characteristics of phosphorus components in the sediments of main rivers into the Bohai Sea

Phosphorus (P) is an essential nutrient for aquatic organisms; however, excessive P inflow to freshwater ecosystems can induce eutrophication. P concentrations in the rivers around the Bohai Sea have been amplified by fertilizer and sewage inputs associated with the development of industry and agriculture. Yet, knowledge of the characteristics of P is lacking at the main rivers which were inflow into the Bohai Sea. We determined the distribution and speciation of P in rivers inflow into the Bohai Sea using the Standards, Measurements and Testing method (SMT) and solution phosphorus nuclear magnetic resonance (31P-NMR). The results indicate that P pollution in the river surface sediments was serious. The total P content in the rivers sediment was between 87.28 to 2610.43mgkg−1, and the main component was Ca-P, which accounted for 34.75%–93.69%; the content of easy released P (Fe/Al/Mn-P) was less than that of HCl-P. Six P species, including two inorganic P species (orthophosphate and pyrophosphate) and four organic P (OP) components (phosphonates, orthophosphate monoesters, phospholipids and DNA-P) were detected in the NaOH-EDTA extracts by 31P-NMR. The main content orthophosphate was between 18.35 to 1681.31mgkg−1, and the orthophosphate monoester as a main kind of components of the OP, represented 0–31.39% of the TP. Because the heavy pollution heavily polluted zones in the Haihe basin includes the Luan River, the Yongdingxin River, and the Ziya River, the content of TP, OP and ortho-P in their sediments were relatively high. To be our knowledge, this is the first systematic study for the characteristics of P components in the rivers which were inflow into the Bohai River, and this study will support nutrition management and eutrophication risk control.

Impact of fertilization on soil polyphenol dynamics and carbon accumulation in a tea plantation, Southern China

The strong role that soil polyphenols play in soil organic matter (SOM) formation affects soil carbon sequestration. N deposition, which comes from man-made fertilizer, influences plant growth and soil biochemical properties therefore greatly regulates soil polyphenol metabolism. The objective of this experiment was to understand the effect of fertilizer form and rate on soil polyphenol dynamics as well as to understand the potential relationship between soil phenols and C accumulation. Urea, rapeseed cake, and chicken manure, respectively, referred as N, B, and F in the text, were applied at three rates (low N, medium N, and high N, referred as 1, 2, and 3 in the text, respectively); plots without fertilization were set as control (CK, for short). Seasonal dynamics of soil total polyphenol (Tp) and bound polyphenol (Bp) concentrations were monitored. Polyphenol oxidase (PPO), peroxidase (POD), and soil fluorescein diacetate (FDA) hydrolysis activities, all factors relevant to polyphenol metabolism, were measured simultaneously. The relationship between soil polyphenols and soil C concentration was also determined. N-fertilization altered the seasonal change pattern and the accumulation level of soil Tp and Bp, which possibly resulted from the enhancement of soil microbial activities and the change of soil nutrient status. Positive linear correlation was observed between soil Tp and TC (total C) contents, which means fertilization could influence C accumulation through affecting the metabolism of soil polyphenols. Soil chemical characteristics and enzyme activities that relate to soil polyphenol metabolism were influenced by fertilization as well. Mitigated TC increment was observed in most fertilization treatments mainly due to the increased SOM decomposition rate. Our findings reveal the important role of soil phenols played in C accumulation in a tea plantation due to the significant, positive linear relationship between soil Tp and TC. Long-term studies, combined with soil microorganism community structure, soil humification, and tea leaf litter decomposition experiments, are necessary for fully understanding the role that polyphenols play in soil C cycle.

Effects of Water-level on Water Quality of Reservoir in Numerical Simulated Experiments

There are many factors that affect the quality of reservoir water, one of the direct factor is water level of reservoirs. To quantitatively study the water quality in different water level of a source water reservoir, numerical simulation was carried out. Firstly, the reservoir hydrodynamic-water quality model was developed, and verified by the field data from reservoir administration. Then the models were used to predict the impact of water-level change on the water quality. The simulation results showed that at low water-level pollutants dispersal ability decreased, and increased at higher water-level. At low water-level, the contents of TN and TP were higher, compared with higher water-level condition, in water body of the reservoir. The simulation results have theoretical and practical significance for evaluating water quality impact of lowered water-level operation and water quality protection of reservoirs.

Physicochemical and microbiological quality of the treated wastewater of the Marrakech WWTP for irrigation

The urban district of Marrakech has a wastewater treatment plant of activated sludge type. Water treated by this WTTP is intended for the irrigation of golf courses. Tertiary treatment can extract any undesirable substance not removed by the steps before. The aim of this work is to characterize the physico-chemical and microbiological quality of the treated water and to assess the effectiveness of tertiary treatment. The pH varies between 7.1 and 7.7 which is in the range recommended by both the Moroccan and the USEPA standards. The COD content fluctuates between 24.87 and 52.33 mg O 2 / l, which is below the limit value of 60 mg O 2 / l recommended by the French legislation. Concentrations of BOD 5 range is between 1.1 and 4.21 mg O 2 / l which is widely below the standard of 30 mg O 2 / l recommended by the WHO and USEPA for the reuse of treated wastewater. For the SM, the value of 30 mg / l is the threshold set by both the WHO, USEPA and French law. The values ​​of SM fluctuate between 2.86 and 8.46 mg / l which are perfectly in accordance with the recommended standard. The content of nitrates does not exceed 5 mg N / l is lower than the limit set by WHO and the Moroccan standard of 30 mg N / l. The TP content is between 1,88 and 6,23 mg P / L compared with the range 6-20 mg / l agreed by WHO. The microbiological analysis, including research faecal coliforms show that the values ​​obtained are below standard 200, 250 and 1000 UF / l respectively recommended by the USEPA, the French legislation and concomitantly the Moroccan standard and WHO . However, the parasitology examination especially of nematodes attests their total absence, showing the effectiveness of the tertiary treatment. Finally, the water at the outlet of the WWTP of Marrakech, destinated for irrigation has a physicochemical and microbiological quality compliant for irrigation.

Alkyl esters content and other quality parameters in oil mill: A response surface methodology study

The quality of the olives oil can be altered during their processing. This paper studies the influence that the washing of olive oils has on their alkyl esters content and on other quality parameters. A Central Composite Rotatable Design (CCRD) with five center points has been used to modify the factors, rotational frequency of the motor of the vertical centrifuge (between 34 and 47 Hz) and percentage of added water (between 6 and 34%). Results show that the content in alkyl esters of olive oils increases by the flow from the decanter to the vertical centrifuge. The use of water in the vertical centrifuge decreases the content in ethyl and methyl esters 0.8 and 0.6 mg/kg, respectively, per percentage unit of added water. The acidity, peroxide index, K232, chlorophyll, and carotenoid contents are slightly altered by the oil flow from the decanter to vertical centrifuge, but not by operating factors. K270, total polyphenols and orthodiphenols change with the speed of the vertical centrifuge, but water does not affect them. For the normal operation frequency of the centrifuge (50 Hz), K270 is increased about 14%, while the total polyphenols and orthodiphenols decrease by 27 and 62%, respectively.Practical applications: Quality control of olive oils (virgin and extra virgin).Olive‐oil production process: differences in the content of EE and TP between the vertical centrifuge way out and the decanter way out.

Water purification of four aquatic plant species with the presence of iron-carbon interior electrolytic substrates.

To compare water purification of common aquatic plants in wetland ecosystem, four common aquatic plant species (Eichhornia crassipes, Nymphaea tetragona, Acorus calamus and Phragmites australis) were used as study species. The effect of aquatic plants on the change of sewage ammonium nitrogen, COD, TP content during different experimental time (1-5 d) with the presence of iron-carbon interior electrolytic substrates were analyzed in small scale experimental apparatus. The results showed that single and combined aquatic plants could effectively remove ammonium nitrogen, COD, TP from the sewage compared with the no-plant control group, but the efficiencies were significantly different among the different species. Ammonium nitrogen removal up to 100% was achieved with E. crassipes in two days, and A. calamus in three days. Each plant combination performed well on ammonium nitrogen removal. Concentration of the sewage COD approached zero with E. crassipes in three days, A. calamus performed secondly. The concentration of COD in combination of E. crassipes and A. calamus water decreased by 85.1% to a minimum of 4.33 mg·L-1. The concentration of TP was the lowest with E. crassipes in four days, and second with P. australis. The lowest concentration of TP was found with the combination of E. crassipes and A. calamusin two days. The combination effect of interior electrolyte and plant was better than that of pure interior electrolyte on the purification of sewage. Plant configuration should be optimized according to the level of pollutants.

Fenced cultivation of water hyacinth for cyanobacterial bloom control.

To achieve the goals of harmful cyanobacterial bloom control and nutrient removal, an eco-engineering project with water hyacinth planted in large-scale enclosures was conducted based on meteorological and hydrographical conditions in Lake Dianchi. Water quality, cyanobacteria distribution, and nutrient (TN, TP) bioaccumulation were investigated. Elevated concentrations of N and P and low Secchi depth (SD) were relevant to large amount of cyanobacteria trapped in regions with water hyacinth, where biomass of the dominant cyanobacteria Microcystis (4.95 × 10(10) cellsL(-1)) was more than 30-fold compared with values of the control. A dramatic increase of TN and TP contents in the plants was found throughout the sampling period. Results from the present study confirmed the great potential to use water hyacinth for cyanobacterial bloom control and nutrient removal in algal lakes such as Lake Dianchi.

Differences of soil nutrients among different vegetation types and their spatial prediction in a small typical karst catchment.

Vegetation types restrict soil structure and heterogeneous processes of elements, which result in difference in spatial distribution of soil nutrients. In this study, the differences in contents of soil nutrients, TN, TP, TK, and soil organic matter (SOM) among different vegetation types were analyzed, and the accuracy of ordinary kriging, regression model and regression model based on vegetation type in predicting soil nutrients was compared. The results showed that, TN, TK and SOM were significantly (P<0.05) correlated to vegetation type, and TP had no significant correlation with vegetation type (P=0.390). TN and SOM had significant difference between shrubbery and arable land. TK had significant difference between arbor and scrub-grassland, shrubbery and arable land, and scrub-grassland and arable land, respectively. In a non-continuous typical small karst catchment, because of high spatial heterogeneity of terrain, the accuracy of multivariate linear regression model based on the real terrain factors of various points was considerably higher than that of ordinary kriging prediction method considering the locations of the known points and prediction points. Moreover, the regression model based on vegetation type improved the prediction accuracy of the TN.

Effects of seasonal variations on soil microbial community composition of two typical zonal vegetation types in the Wuyi Mountains

Seasonal shifts play an important role in soil microbial community composition. This study examined the hypothesis that soil microbial community structure would vary with seasonal shifts in the Wuyi Mountains in Southeast China, and that two representative tree species (Castanopisi carlesii and Cunninghamia lanceolata) may have different soil microbial community composition. Phospholipids fatty acid analysis (PLFA) was used to assess the effect of seasonal shifts and vegetation types on soil microbial community structure. A total of 22 different PLFAs were identified from all the soil samples. The bacterial PLFAs accounted for 62.37% of the total PLFAs, followed by fungi (28.94%), and the minimum was actinomycetes (6.41%). Overall, the level of PLFAs in C. carlesii soil was greater than those in C. lanceolata soil, and significant differences were observed in some seasons. The amounts of total, bacteria, actinomycic and fungal PLFAs significantly changed with the seasons and followed a sequence order (summer > autumn > spring > winter). The bacteria/fungi PLFAs and G (+) /G (-) PLFAs of two vegetation types also changed with the seasons and the ratios in summer and autumn were higher than those in spring and winter. The correlation analysis of microbial PLFAs and soil physicochemical properties showed that the total, bacteria, fungal, actinomycic, G (+) and G (-) PLFAs were significantly positive correlation with TOC, TN, TP, TK and moisture content. We concluded that the seasonal shifts and vegetation types affect soil microbial community composition by changing the soil physicochemical properties.

Study on Thermal Performance of Composites Prepared Using Poly(L-Lactic Acid) and Melamine

The goal of this work was to study the non isothermal and isothermal crystallization behavior of Poly(L-lactic acid) (PLLA) with melamine (TP) through differential scanning calorimeter and optical depolarizer. The study of the crystallization behavior of PLLA/TP composites indicated that TP could promote the crystallization of PLLA. The half time of overall crystallization of PLLA with 1.5 wt% TP, compared with the neat PLLA, gave rise to a decrease from 3999.44 s to the minimum value 228 s at 100 °C. In addition, the cooling rate also affected significantly the crystallization behavior of PLLA. The melting behavior of PLLA/TP composites exhibited a complicated and different melting process after cooling crystallization, and the increasing of TP content made melt mass flow rate of PLLA firstly decrease, then increases.