TP Content Research Articles

Phosphorus release during alkaline treatment of waste activated sludge from wastewater treatment plants with Al salt enhanced phosphorus removal: Speciation and mechanism clarification

Chemical phosphorus removal (CPR) is being increasingly adopted in wastewater treatment plants (WWTPs) to enhance P elimination to comply with stringent discharge limits. However, strategies to recover P enriched in the produced waste activated sludge (WAS) are not well developed. In this study, we investigated the release of P in WAS from three WWTPs employing Al salt enhanced CPR by alkaline treatment. We also monitored P mobilization by tracking the dynamics of P fractions and species, the dissolution of major metals, and sludge cell integrities as pH was altered. The level of aqueous total phosphorus (TPaq) in the sludge increased significantly to >200 mg/L (from <11 mg/L in the raw sludge) as the pH was increased to 12, with the majority being PO4-Paq especially at high pHs. The dominance of non-apatite inorganic phosphorus (NAIP) in the sludge-P, a good correlation observed between aqueous PO4-P and aqueous Al, and the reversibility of P mobilization all suggest that the dissolution of Al-bound P was largely responsible for the sludge-P release. Sludge cell integrity, on the other hand, was not closely correlated with TPaq concentrations. Although the level of TP released in this study is among the highest, a more efficient strategy still needs to be developed to further enhance sludge-P release when TP content in the sludge mixture (TPmx) is considered (TPmx was >800 mg/L in this work).

Phytochemical and Micromorphological Characterization of Croatian Populations of Erodium cicutarium

The aim of this study included the phytochemical screening of extracts and essential oil of Erodium cicutarium (L.) L’Hér. ex Aiton (Geraniaceae), a native traditional medicinal plant from Croatia, as well as a highly detailed micromorphological characterization of its aerial parts. The contents of total polyphenols and tannins (TP and T), total flavonoids (TF), and total hydroxycinnamic derivatives (THD) in plant extracts were quantified in plant material from 4 localities (Plitvice, Podvinje, Buzin, and Trešnjevka). The contents of TP, T, TF, and THD significantly varied depending on the collection site, and were in the range of 4.78%-12.85% (TP), 3.23%-5.80% (T), 0.42%-1.09% (TF), and 1.08%-2.59% (THD) of dry weight of plant material, with the Plitvice collection having the highest polyphenol content. GC-MS analysis of the essential oils showed a similarity in composition of the major compounds from all investigated populations. Fifty compounds were identified in all 4 investigated oils (90.4%-96.7% of total oil) and classified into 7 structural classes, with hydrocarbons (59.8%-65.7%) as the main class of constituents. Two types of trichomes, nonglandular and glandular, were observed on the calyces, leaves, and stems, including 3 capitate trichome types. The bioactive substances and micromorphological characterization of Croatian populations of E. cicutarium were investigated for the first time. In general, the scanning electron microscopy imaging of Erodium cicitarium trichomes has not been reported before.

Effects of dietary Gelsemium elegans alkaloids on growth performance, immune responses and disease resistance of Megalobrama amblycephala

The present study aim to investigate the effects of dietary Gelsemium elegans alkaloids supplementation in Megalobrama amblycephala. A basal diet supplemented with 0, 5, 10, 20 and 40 mg/kg G. elegans alkaloids were fed to M. amblycephala for 12 weeks. The study indicated that dietary 20 mg/kg and 40 mg/kg G. elegans alkaloids supplementation could significantly improve final body weight (FBW), weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) (P < 0.05). The 20 mg/kg and 40 mg/kg G. elegans alkaloids groups showed significantly higher whole body and muscle crude protein and crude lipid contents compared to the control group (P < 0.05). The amino acid contents in muscle were also significantly increased in 20 mg/kg and 40 mg/kg groups (P < 0.05). Dietary 40 mg/kg G. elegans alkaloids had a significant effect on the contents of LDH, AST, ALT, ALP, TG, TC, LDL-C, HDL-C, ALB and TP in M. amblycephala (P < 0.05). Fish fed 20 mg/kg and 40 mg/kg dietary G. elegans alkaloids showed significant increase in complement 3, complement 4 and immunoglobulin M contents. The liver antioxidant enzymes (SOD, CAT and T-AOC) and MDA content significantly increased at 20 mg/kg and 40 mg/kg G. elegans alkaloids supplement (P < 0.05). The mRNA levels of immune-related genes IL-1β, IL8, TNF-α and IFN-α were significantly up-regulated, whereas TGF-β and IL10 genes were significantly down-regulated in the liver, spleen and head kidney of fish fed dietary supplementation with 20 mg/kg and 40 mg/kg G. elegans alkaloids. After challenge with Aeromonas hydrophila, significant higher survival rate was observed at 20 mg/kg and 40 mg/kg G. elegans alkaloids supplement (P < 0.05). Therefore, these results indicated that M. amblycephala fed a diet supplemented with 20 mg/kg and 40 mg/kg G. elegans alkaloids could significantly promote its growth performance, lipids and amino acids deposition, immune ability and resistance to Aeromonas hydrophila.

Trophic position and individual feeding habits as drivers of differential PCB bioaccumulation in fish populations

Despite PCBs being banned since the 1980's, some European peri-alpine lakes, and consequently their fish populations, are still contaminated by these xenobiotics. We investigated the relative contribution of physiological and trophic factors that could be implicated in fish PCB bioaccumulation in Lake Bourget (France), one of the most contaminated in Europe, by collecting Arctic char (n = 55) and European whitefish (n = 89) from 2013 to 2016. Concentrations of 7 indicator PCBs were 9–168 ng.g w.w−1 in whitefish and 90–701 ng.g w.w−1 in Arctic char. The fish trophic positions calculated from δ 15N values were positively correlated with PCB concentrations (r2 = 0.45; p < 0.001). A biomagnification model relying on TP and lipid content of fish was then designed, and it confirmed this result. A Bayesian mixing model based on δ 13C and δ 15N values was used to estimate the relative contribution of preys in the fish diet, which explained a significant proportion of the biomagnification model residuals (i.e., 17%). Zooplankton consumption was negatively correlated with PCB concentrations, whereas consumption of chironomids enhanced the PCB burden in fish. Correction of the biomagnification model for individual diets of fish increased the correlation between the predicted and measured fish PCB contents (R2 = 0.71; p < 0.001), highlighting the importance of fish feeding habits in the bioaccumulation process.

Spectrum Modelling of TN, TP and TK Content in Soil with Human Interference

Spectrum Modelling of TN, TP and TK Content in Soil with Human Interference

The Influence of Periphyton Biofilm on Phosphorus Migration in Sediments

The objective of this study was to analyze the influence of periphyton biofilm on nutrient releases from sediments in ponds and lakes. The physico-chemical parameters in the overlying water, the TP content, and the P forms in the sediments and periphyton biofilm were measured. The results showed that (1) periphyton biofilm could change the physico-chemical indexes in the overlying water; furthermore, the periphyton biofilm influenced the release of N and P from sediments, and its extent of influence was closely related to the nutrient levels of the sediments. (2) The periphyton biofilms effectively reduced the concentrations of N and P in sediments with different nutritional levels (P < 0.05). The average daily TN removal rates were 52% and 25% in the pond and lake microcosms, respectively, and the average daily TP removal rates were 1.06% and 20.9% in the pond and lake microcosms, respectively. This result suggested that periphyton biofilms acted as biological buffers for nutrient cycling between sediments and overlying water; these buffering effects were mainly through the absorption, filtration, and precipitation of nutrients. (3) The TP content and P forms of the periphyton biofilm were different between the pond and lake microcosms, which indicated that the P forms of the periphyton biofilm were potentially influenced by the nutritional levels of the sediments.

Study on spatial-temporal distribution of different forms of phosphorus in wetland sediments

As an important factor for controlling phosphorus adsorption and release in wetland system, the forms of phosphorus in sediment has a decisive effect on phosphorus retention and release. Four different wetland systems were selected to study the phosphorus status and its environmental effects in wetland sediment. Phosphorus forms in sediments were related to aquatic plant characteristics. In the Vallisneria Linn. wetland system, the content of Ca-P of sediment was higher than the other systems because of its higher pH of the water. The maximum phosphorus adsorption capacity is 766.82-840.27 mg/kg. The content of Ca-P and TP have very good correlation with Smax. When the phosphorus concentration in the water is lower than 0.1mg/L, the surface sediment is no longer a “sink” of phosphorus but a “source” of phosphorus. The changes of TP in four wetland sediments basically follow a similar trend. The phosphorus content in the sediment decreased during the growth period of aquatic plants, and the wetland sediment as the phosphorus “source” provided the biomass for the growth of the aquatic plants. In autumn and winter, phosphorus in plants is released into wetland again with the decay of plants, resulting in the increase of phosphorus content in sediment.

Distribution and Bioavability of Phosphorus in Surface Sediments in Megalopolis: A Case Study of Chengdu

A total of 33 surface sediments were collected from rivers in Chengdu. The content of phosphorus species was measured with the chemical continuous extraction method (SMT) and in situ monitoring techniques (DGT). Multivariate statistical analysis was used to analyze the spatial distribution of phosphorus species in sediments. The release flux of DGT-P in sediments and their pore water was calculated in this study. It is helpful to understand the influence of sediment endogenous pollution and human activities on the environment. The results show that the phosphorus species have a spatial variability. The average content of TP in the surface sediments is 1132.41 mg·kg-1, which is higher than the background value of 365.00 mg·kg-1 in Chengdu. The Ca-P is the most dominant species, accounting for 70.58% of the TP on average. The study area is divided into three groups based on spatial clustering. Groups 1 and 3 show large differences of phosphorus morphological structures, while Group 2 is small. The contents of phosphorus in the surface sediment of Groups 1 and 3 are generally higher than those of Group 2. The DGT-P concentration has a good correlation with the soluble DTP concentration, bioavailable Fe/Al-P, and OP concentration, respectively. The DGT technology can be used as a fast, in situ, reliable method for measurements of the bioavailable content of sediments. The higher release fluxes of bioavailable phosphorus are N8, W11, and N2, which are 20.05, 17.13, and 14.79 mg·(m2·d)-1 respectively. The available phosphorus release capacity is closely related to human activities.

Optimization of ultrasound-assisted extraction of total polyphenolic compounds from Juglans nigra L. leaves

The ultrasound-assisted extraction of Juglans nigra L. leaves was optimized with respect to total phenolic content ( TP ) of the extracts by varying the concentration of aqueous ethanol solution ( E ) and different solvent-to-solid ratio ( S ). The influence and optimum of the operating parameters ( E and S ) was examined using response surface methodology (RSM). The statistical criteria indicated the adequacy, reliability and precision of the developed RSM model. RSM showed that maximum extraction yield of TP 28.59 mg g -1 of draw plant was achieved at the optimal values of 50% E and 20 kg kg -1 S. Using the modelled optimized con­dit­ions, the detected relative difference between the predicted and the experimental yield was ±2.3 %. The determined TP content in the extracts varied from 12.54 to 29.26 mg GAE g -1 of dry plant indicated that J. nigra is a valuable source of phe­nolic substances. The extracts of J. nigra leaves obtained under optimal con­dit­ions showed good antioxidant activity ( IC 50 = = 18.91±0.03 μg cm -3 ) which was determined by the scavenging effect on 2,2- -diphenyl-1-picrylhydrazyl radical. The optimization of the TP extraction process is the important step in improving techno-economics of the potential commercial preparation of J. nigra extracts, as natural source of antioxidants.

Research on variation of non-point source pollutant of field in Qingtongxia Irrigation District

An experiment was conducted to research the non-point source pollutant of field in qingtongxia irrigation area, and its variation features was also analyzed. The results showed that the rate of pollutants’ concentration in water of the paddy field during the crop growing season was in the order of salinity, in agricultural ditch of the paddy field which is in the order of salinity, and in agricultural ditch of the dry field which is in the order of . The salinity concentration in field changes greatly. The content and loss quantity of TP are rarely small. The nitrogen loss is mainly . The variation process of pollutants’ concentration in field was closely related to fertilization, irrigation process, the crop growing season and so on.

Different Influences of Bacterial Communities on Fe (III) Reduction and Phosphorus Availability in Sediments of the Cyanobacteria- and Macrophyte-Dominated Zones.

Little is known about the effects of bacterial community on iron (Fe) and phosphorus (P) cycles in sediments under different primary producer habitats in different seasons. Lake Taihu has both the cyanobacteria- and macrophyte-dominated lake zones. In this work, the abundance and structure of bacterial community was investigated using qPCR and 16S rRNA gene high throughput sequencing, respectively. Compared with the sediments in the cyanobacteria-dominated lake zone, sediments in the macrophyte-dominated lake zone had higher TP, TOC and TN contents but lower DO and Eh values. Dissolved reactive P, dissolved Fe, and their molar ratios (Fe/P) were lower in the sediments of the cyanobacteria-dominated lake zone than those in the macrophyte-dominated lake zone. Consistent with this was the significantly lower abundance of total and typical Fe redox transforming bacteria in the sediment of the cyanobacteria-dominated lake zone than those in the macrophyte-dominated lake zone. Correlation analyses also revealed positive influence of abundances of total bacteria and typical Fe reducing bacteria on dissolved Fe and Fe/P ratio. The results showed that, in the cyanobacteria-dominated open water zone, Acidimicrobiaceae was capable of Fe metabolism, contributing to higher P flux in summer. In the cyanobacteria-dominated bay, Sva0081 sediment group and Desulfobulbaceae could transform sulfate to sulfide, which resulted in the reduction of Fe (III), while in the macrophyte-dominated zones, Clostridium sensu stricto 1 could couple oxidation of organic carbon with the reduction of Fe (III). The present study adds new knowledge linking the bacterial communities with the physicochemical cycles of Fe and P in sediments under different primary producer habitats.

Effects of vegetation restoration on soil quality in degraded karst landscapes of southwest China

Vegetation restoration was implemented to control soil erosion in the karst regions of southwest China. It is essential to assess the soil function and quality scientifically during this process and to adopt suitable management practices for this area. However, few studies have been conducted to comprehensively evaluate the effect of vegetation restoration on soil quality in this severely eroded karst area. By taking 302 soil samples from 11 vegetation types, this study investigated the influence of different types of vegetation restoration on soil quality using an integrated soil quality index (SQI) and a generalized linear model (GLM). Vegetation types had significant effects on soil properties and thus on soil quality. SQI was developed by using TN, TP, TK, AP, and clay content; TN had highest weighting values (0.58), which indicated that it contributed the most to final SQI. The highest and lowest SQI values were observed for primary forest and cropland, respectively. Overall, vegetation restoration (e.g., natural restoration, artificial forests and artificial grassland) improved soil quality significantly. A GLM model explained 73.20% of the total variation in SQI, and vegetation type explained the largest proportion (46.39%) of the variation, which implies that the vegetation restoration practices can greatly enhance the soil quality in karst landscapes of southwest China. The results of this study may be used to improve implication of ecological restoration and management in degraded regions.

Distribution characteristics and ecological risk assessment of nutrients in sediment particles in Hangzhou Bay, China

In April 2011, the contents of TC, TP, TN, NH4-N and the particle size and pH of surface sediment and suspended particulate matter at 18 stations in Hangzhou Bay were detected and analyzed. The content of nutrients in the bay features high values in the middle and mouth of the bay while low values at the top of the bay, and low values on the north side while high values on the south side of the bay. The contents of TC, TN and NH4-N in suspended particulate matter were significantly higher than those in surface sediments. To a certain extent, this feature reflected the effect of water and sediment transportation. Hydrodynamics in the studied area were active. The sediment differentiation caused by the repeated suspension-transport and sedimentation of the tidal current was one of the important reasons for the difference of the contents and dispersion of nutrients in suspended sediments and surface sediments. The contents of TP in the Hangzhou Bay were high and the contents of most of the sediment samples collected exceeded the class I, which indicated that the sediments in Hangzhou Bay had been contaminated. However, most areas were still within the range of benthic organisms. In terms of the distribution of pollution, the TP had the most obvious toxicity in front of the south shore of Hangzhou Bay.

Green vegetation to remove contaminants in surface runoff from an urban area, Xuzhou, China

Effects of different Greenbelt Plant configurations on pollutants from Urban Surface runoff varies. A study on the surface runoff samples of five different plant communities in the same green space between Fuchun Road and Shundihe River in Xuzhou City in 2017 due to 12 rainfall events. The results showed that: the content of Pb of Osmanthus fragrans + Crataegus pinnatifida + Nandina domestica community was 0.263 mg.L-1 in summer(months of 4-6 ), and it was lower than that in autumn (months of 7-9 ) (0.333 mg.L-1), spring(months of 1-3 ) (0.444 mg.L-1) and winter (months of 10-12) (0.448 mg.L-1). Under the condition of less rainfall in winter and spring with longer rainfall interval, the pollutant content of surface runoff is higher in five plant communities studied than that in summer with shorter rainfall intervals. The order of average content of Zn in surface runoff in 1 year was as follows: Koelreuteria integrifoliola + Forsythia suspensa + Cynodon dactylon community (0.194 mg.L-1) > Cedrus deodara + F. suspensa + C. dactylon community (0.178mg.L-1) > O. fragrans + C. pinnatifida + N. domestica community (0.166 mg.L-1)> Cinnamomum camphora + Photinia serrulata community (0.149 mg.L-1) > C. camphora + N. domestica + C. dactylon community (0.128 mg.L-1). The average contents of COD, Cu, Pb, TSS, TP, TN and TOC were in the same order in the five communities studied. Therefore, in urban green space plant design, the plant community of evergreen tree and shrub such as C. camphora + N. domestica + C. dactylon community should be allocated as far as possible in order to purify the urban water resources environment.

The seasonal effects on the encrustation of charophytes in two hard-water lakes.

Encrustation and element content of six charophyte species from two hard-water lakes were investigated monthly for a period of 1year. Seasonal patterns were analyzed for the interaction of water chemistry. Encrustation followed a seasonal pattern for Chara contraria, Chara subspinosa, and Nitellopsis obtusa in Lake Krüselin and for Chara globularis and Chara tomentosa in Lake Lützlow. However, no seasonality in the precipitated CaCO3 was observed for C.subspinosa in Lake Lützlow and for C.tomentosa in Lake Krüselin, indicating a lake-specific dependency. Species-specific encrustation was found. Chara contraria and N.obtusa encrusted the most in June and August, whereas C.subspinosa and Nitella flexilis/opaca exhibited lowest encrustation in March and April. The precipitated CaCO3 of charophytes correlated negatively to the concentration of total inorganic carbon in both lakes. Element content of plant dry weight was species-specific for Ca and K, and lake-specific for Mg. No specific pattern was found for the TP and Fe contents. The results showed seasonal, species, and lake-specific influences on the encrustation of charophytes.

Spatial distribution of sediment nitrogen and phosphorus in Lake Taihu from a hydrodynamics-induced transport perspective

Hydrodynamics play an important role in sediment nutrient dynamics in large shallow eutrophic lakes. In this study, the spatial patterns of sediment nitrogen and phosphorus in Lake Taihu were compared from a hydrodynamics-induced transport perspective based on high-resolution investigation of sediment, field observations, numerical simulations and long-term ecological data analysis. The results showed that sediments were primarily distributed in the west and southeast portions of the lake. Additionally, the total nitrogen (TN) and phosphorus (TP) stored in the active sediments was 166,329 t and 67,112.4 t, respectively. The sediment TN content was 319.4–3123.8 mg kg−1, with high content areas being primarily located in the Zhushan, Meiliang and East Taihu bays. The external nitrogen-containing nutrients in the overlying water, which is mostly dissolved nitrogen, can be horizontally transported by lake currents to the water areas with high biomass levels and weak vertical hydrodynamic disturbance where sediment nitrogen enrichment primarily occurs via bio-deposition. The sediment TP content ranged between 382.6 and 1314.1 mg kg−1, and the high content areas were primarily distributed near the inflowing river mouths. Sediment phosphorus enrichment primarily occurred via physical and chemical deposition. Surface waves caused vertical phosphorus transport from sediments to the overlying water but had a limited effect on its spatial distribution. Although the horizontal transport of phosphorus was found to be weaker than that of nitrogen, short-distance vertical transport of sediment phosphorus may relieve nutrient limitations, leading to maintenance of cyanobacterial blooms found in Lake Taihu.

Phosphorus Forms and Distribution Characteristics in the Sediment and Soil of the Water-Level-fluctuating Zone in the Main Stream of the Three Gorges Reservoir

Hydrological regimes changed after the Three Gorges Reservoir (TGR) became fully operational, with the water level fluctuating between 145 m and 175 m. This has altered phosphorus (P) distribution within sediments and soils of the water-level-fluctuating zone (WLFZ). Eleven field investigations within the main stream were carried out in June 2016. The aim of the study was to determine lateral (sediment and WLFZ soil) and longitudinal variations (from the end of the backwater area to the Three Gorges Dam) of phosphorus species. P fractions were analyzed using a Standards, Measurements, and Testing (SMT) protocol. Results showed that both TP and NaOH-P content in sediment exhibited a clear increasing trend from the end of the backwater area to the Three Gorges Dam, while HCl-P declined. Average of totals P, OP (organic P), HCl-extracted P (HCl-P, calcium-bond P), and NaOH-extracted P (NaOH-P, metal oxide-bound P) in sediment were (859.6±106.8), (224.6±113.9), (435.3±77.7), and (101.5±31.6) mg·kg-1, respectively. The concentration average of P species in sediment was higher than in WLFZ soil. In both sediment and soil, HCl-P was the main form of P, accounting for 51.3% and 58.2% of TP, while the ratio of NaOH-P to TP was 11.7% and 8.1%, respectively. P fractions with a higher coefficient of variation had greater spatial heterogeneity.

Reconstructing the Trophic History of an Alpine Lake (High Tatra Mts.) Using Subfossil Diatoms: Disentangling the Effects of Climate and Human Influence

Diatom analysis was undertaken on a 200-year sediment record in an alpine lake (Popradské pleso, Tatra Mountains, Central Europe). Due to its remote character and well-documented human influence since the mid-nineteenth century, it allows a study of the relationship between anthropogenic pressures and diatom assemblages. Altogether, 122 diatom taxa of 40 genera were identified, and two major taxonomic shifts were revealed in the stratigraphic record. The timing of the first significant shift in ~ 1850 precludes the possibility of being caused by direct human activities, since according to historic documents there was neither continuous human presence nor grazing in the valley before that time. In addition, the direct effect of organic pollution early in the 1960s connected with the operation of a tourist hotel was not clearly reflected in the diatom signal. The diatom-inferred total phosphorus (DI-TP) reconstruction indicated the highest TP content well before the most direct wastewater pollution from a newly built hotel. There was a considerable effect of climate to diatom assemblage structure as well as diatom life forms. Our results suggest that direct organic pollution influenced the diatom communities less than expected, and the main driver of change was climate warming. We hypothesize that it is because of the short residence time of the lake, since it has both strong inlet and outlet, and it has been showed that the inlet had significant effect on benthic communities in the past. At the same time, fish manipulation could have been the reason for some fluctuation in DI-TP unrelated to climate and organic pollution.

Temporal and Spatial Changes in Sediment Nutrients and Heavy Metals of the Danjiangkou Reservoir Before and After Water Division of the Mid-route Project

Reservoir/lake sediments are potential pollutant acceptors and sources of pollution. The Danjiangkou Reservoir, as the largest drinking water source in China, is the source water area for the Mid-route Project of the South-North Water Diversion. To illustrate the temporal and spatial changes in the environmental risks of both nutrients and heavy metals in the surface sediments of Danjiangkou Reservoir, the levels of pH, OM, TP, TN, and six kinds of metal elements during the period 2011-2016 were measured at five ecological sites. Canadian freshwater sediment quality guidelines for aquatic environments (from the CCME) were used to assess the potential ecological risks. The results showed that the contents of OM, TP, and TN in the surface sediments were 25.85, 0.57, and 1.34 g·kg-1, respectively, and those of Cr, Mn, Cu, Zn, Cd, and Pb were 57.96, 521.78, 13.91, 195.74, 0.37, and 12.92 mg·kg-1, respectively. The contents of both Zn and Cd were under the corresponding Ⅱ-level standards of soil environmental quality, but the contents of the other four heavy metals were lower than their corresponding I-level standards. After water diversion of the Mid-route Project, the OM, TN, Mn, and Zn contents increased, and the TP and other heavy metal contents displayed downward trends. Excluding the pH value, the distribution of measured nutrients and heavy metals in the surface sediments of the Danjiangkou Reservoir reached the extremely significant level (P<0.01). OM in the sediments was negatively correlated with TN and Pb, but had positive correlations with the other indicators measured. The results from the potential ecological risk assessment showed that:①Cd, Cu, and Pb had no harmful effects on organisms; ② OM had low ecological risk in most years; ③ the risk of TP was between zero and low ecological risk; and ④Cr, Zn, and TN had low ecological risk in most cases. The K and H sites had higher ecological risk for Cr, Zn, and TN, thus attention should be paid to those cases. These results illustrate the effects of human activities on nutrients and heavy metals in surface sediments.

Determination of tocopherol and tocotrienol contents in maize by in vitro digestion and chemical methods

α, γ, and δ-tocopherols (TPs) and α, γ, and δ-tocotrienols (TTs) in native and partially cooked samples of Big Flint Maize (BFM), Pop Corn (PC), and Red Maize (RM) were analyzed after chemical method of extraction and in vitro digestion of partially cooked samples. Native RM contained higher TP, TT, α-TP, α-TT, and γ-TT contents than BFM and PC. TP and TT component contents were higher in native maize than in partially cooked samples by the chemical method. TP and TT contents of in vitro digestion (bioaccessible) were lower than those obtained by the chemical method. BFM contained higher bioaccessible TP, TT, α-TP, γ-TP, γ-TT and δ-TT contents. BFM and PC showed higher percent bioaccessibility. The percent bioaccessibility of γ-TP and γ-TT tended to be higher than that of α-TP and α-TT. These results highlight differences in the contents of individual vitamin E isomers obtained by in vitro digestion and chemical method.