Phosphorus Ratio Research Articles

Drawdown of Atmospheric pCO2 Via Variable Particle Flux Stoichiometry in the Ocean Twilight Zone

AbstractThe strength of the biological soft tissue pump in the ocean critically depends on how much organic carbon is produced via photosynthesis and how efficiently the carbon is transferred to the ocean interior. For a given amount of limiting nutrient, phosphate, soft tissue pump would be strengthened if the carbon (C) to phosphorus (P) ratio of sinking organic matter increases as the remineralization length scale of C increases. Here, we present a new data compilation of particle flux stoichiometry and show that C:P of sinking particulate organic matter (POM) in the ocean twilight zone on average is likely to be higher than the C:P ratio of surface suspended POM. We further demonstrate using a physics‐biology coupled global ocean model combined with a theory from first principles that an increase in C:P export flux ratio in the ocean's twilight zone can lead to a considerable drawdown of atmospheric pCO2.

Effects of Soil Properties, Temperature and Disturbance on Diversity and Functional Composition of Plant Communities Along a Steep Elevational Gradient on Tenerife

Elevational variation of vegetation has been of interest for centuries, and a prominent example for such pronounced vegetation changes can be found along the steep elevational gradient on Tenerife, Canary Islands, 200 km off the West-African cost. The 3,718-m ascent to the peak of the island volcano, Teide, offers a unique opportunity to investigate associated changes in vegetation. However, elevation is not a directly acting factor, but represents several natural environmental gradients. While the elevational variation of temperature is globally rather uniform and temperature effects on plant communities are well understood, much less is known about the region-specific elevational change of chemical soil properties and their impact on plant communities along elevational gradients. Because human interference takes place even at high-elevation areas, we considered human-induced disturbance as important third factor acting upon plant community assemblages. In our study, we compared the effects of soil properties, temperature and disturbance on species richness, functional identity and functional diversity of plant communities along the elevational gradient on Tenerife. We used pairs of study plots: directly adjacent to a road and in natural vegetation close by. In each plot, we did vegetation relevées, took soil samples, and installed temperature loggers. Additionally, we collected leaf samples to measure leaf functional traits of 80% of the recorded species. With increasing elevation, soil cation concentrations, cation exchange capacity (CEC) and pH decreased significantly, while the soil carbon to phosphorus ratio slightly peaked at mid-elevations. Temperature had the strongest effects, increasing species richness and favoring communities with fast resource acquisition. Species richness was higher at road verges, indicating the positive effect of reduced competition and artificially generated heterogeneity. However, we did not detect road effects on plant functional characteristics. Vice versa, we did not find soil effects on species richness, but increased concentrations of soil cations favored acquisitive communities. Surprisingly, we could not reveal any influence on community functional diversity. The importance of temperature aligns with findings from large-scale biogeographic studies. However, our results also emphasize that it is necessary to consider the effects of local abiotic drivers, like soil properties and disturbance, to understand variation in plant communities.

Stoichiometric theory shapes enzyme kinetics in paddy bulk soil but not in rhizosphere soil

AbstractThe available carbon (C) to phosphorus (P) ratio in the soil is regulated by extracellular hydrolases for C and P acquisition by microbes and plants. However, the stoichiometric relationship between acquiring C and P in paddy rhizosphere and bulk soils remains unclear. The objective was to explore the underlying mechanisms of C and P acquisition stoichiometry in rhizosphere and bulk soils in response to P fertilization and cellulose addition. Amendment with either cellulose or P separately caused a significant increase in the maximal velocity (Vmax) of C acquisition enzymes (β‐1,4‐glucosidase and β‐cellobiohydrolase) but decreased that of P acquisition enzymes (acid and alkaline phosphomonoesterases) in bulk soil. In contrast, lower Vmax values of C and P acquisition enzymes were observed in rhizosphere soil than in bulk soil. The co‐application of cellulose and P increased the Vmax of P acquisition enzymes in rhizosphere soil but decreased that of only alkaline phosphomonoesterase in bulk soil. Results show that P availability and labile‐C content co‐regulated the P/C acquisition ratio, and two inverse linear relationships were observed. Specifically, the P/C acquisition ratio was negatively related to both the dissolved organic C/Olsen‐P ratio and the microbial biomass C/P ratio in rhizosphere soil. However, the P/C acquisition ratio was positively related to both the dissolved organic C/Olsen‐P ratio and the microbial biomass C/P ratio in bulk soil. Overall, microbes mineralized less organic P to acquire P in paddy soil rhizosphere (i.e., containing higher labile‐C) than in bulk soil (i.e., having lower labile‐C contents).

Evaluation of calcium to phosphorus ratio in spot urine samples as a practical method to monitor phosphorus intake adequacy in sows.

The objective of this study was to evaluate the reliability of using Ca to P ratio measured in spot urine samples to assess P intake adequacy in gestating and lactating sows. A total of 36 sows were fed one of six concentrations of dietary total P (0.40%, 0.48%, 0.56%, 0.64%, 0.72%, and 0.80%) from day 7.5 ± 1 after breeding until the end of lactation (day 26.6 ± 1). Dietary Ca to P ratio was maintained constant across treatments at 1.25:1. Total 24-h urine samples were collected in mid- and late gestation (days 77.1 ± 2 and 112.4 ± 1), and early and late lactation (days 4.5 ± 1 and 18.2 ± 1). In parallel to 24-h collections, spot urine samples were collected at three different times (early morning, late morning, and late afternoon) in late gestation and late lactation. Urine Ca and P concentrations were measured and Ca to P ratio was calculated. Sows were classified as P-adequate or P-deficient according to dietary P intake. Urine Ca to P ratio was greater in sows fed P-deficient diets than sows fed P-adequate diets (P < 0.001). Receiver operating characteristic (ROC) curves were used to determine the cutoff values for urine Ca to P ratio to predict P intake adequacy. Three different categories of P intake were defined according to urine Ca to P ratio: deficient, adequate, and excessive. The area under the ROC for Ca to P ratio was 0.88 (95% CI 0.81 to 0.95). Best cutoff value of urine Ca to P ratio was 1.5 (sensitivity 94% and specificity 68%) to identify sows fed P-deficient diets and 0.5 for P-excessive diets (sensitivity 82% and specificity 82%). A strong relationship between Ca to P ratio in 24-h and spot urine samples was determined (r = 0.93, P < 0.01), independent of physiological state and collection time of spot samples (adjusted-R2 = 0.86, P < 0.01). The degree of agreement between spot and 24-h urine for P intake adequacy, assessed by Cohen's weighted kappa analysis, was substantial (0.78, 95% CI 0.69 to 0.88). We conclude that urinary Ca to P ratio provides a reliable prediction of the adequacy of P intake in reproducing sows. Urinary Ca to P ratio measurements in random spot urinary offers a practical method to determine dietary P adequacy.

Recent Advances in the Role of Diet in Bone and Mineral Disorders in Chronic Kidney Disease.

Chronic kidney disease mineral and bone disease (CKD-MBD) is a common complication of kidney disease and is strongly influenced by diet. The purpose of this manuscript is to review recent advances in the role of diet in CKD-MBD over the last 5 years. Many of the recent studies examining the role of diet in CKD-MBD have focused on the adverse effects of high phosphorus consumption on bone health and metabolism. In general, the studies have shown that high phosphorus consumption worsens markers of bone and mineral metabolism but that eating a diet with a calcium to phosphorus ratio closer to 1:1 can attenuate some of these effects. Recent studies also showed that dietary counseling is efficacious for improving markers of CKD-MBD. High consumption of phosphorus aggravates CKD-MBD. Dietary counseling may ameliorate these effects, for example, by consuming diets with higher calcium to phosphorus ratios.

Resource limitation and modeled microbial metabolism along an elevation gradient

Soil microbes have a great influence on the feedbacks of carbon (C)-climate, and their metabolic activities are limited by resource availability. Altitudinal gradients strongly affect soil microbial communities, but the effects on microbial resource limitation and their regulation for C dynamics remain unclear. In this study, we designed an altitudinal gradient experiment that included six altitudinal sites from 1308 m to 2600 m in the Qinling Mountains, China. The enzymatic stoichiometry was determined and modeled to investigate microbial resource limitations and major microbial metabolism processes (e.g., organic C decomposition rate and microbial respiration rate) along the elevation gradient. Other environmental variables including mean annual temperature (MAT) and mean annual precipitation (MAP), the C: nitrogen (N): phosphorus (P) ratio in soil total nutrients, available nutrients, and microbial biomass were also measured. The results showed that soil microbes suffered from N limitation in our study and microbial N limitation significantly increased with increasing elevation. But the rates of both organic C decomposition and microbial respiration greatly decreased with increased elevation. These trends suggest that warming induced by elevation change might relieve N limitation for microbes and lead to increased soil C release. Redundancy analysis (RDA) showed that MAT and soil nutrient stoichiometry, particularly for the DOC: TDN ratio, explained more variations for changes in microbial N limitation and major microbial processes. Collectively, our study demonstrated that the higher microbial N limitation at high elevation may be beneficial to soil carbon accumulation by changing the C: N ratio, which provided insights into microbially mediated soil carbon release under global warming.

Novel Protein to Phosphorous Ratio Score Predicts Mortality in Hemodialysis Patients

Lowering serum phosphorus in people on hemodialysis may improve their survival. However, prior studies have shown that restricting dietary protein intake, a major source of phosphorus, is associated with higher mortality. We hypothesized that a novel metric that incorporates both these values commensurately can improve survival prediction. We used serum phosphorous and normalized protein catabolic rate (nPCR), a surrogate of dietary protein intake, to form a new metric R that was used to examine the associations with mortality in 63,016 people on hemodialysis (HD) of oneyear after treatment initiation. Survival models were adjusted for case-mix, malnutrition-inflammation cachexia syndrome (MICS), and residual kidney function (RKF). Individuals treated with hemodialysis were divided into five groups in accordance with R value. Group 1 included sick individuals with high phosphorous and low nPCR. Group 5 included individuals with low phosphorous and high nPCR. After 1-year follow-up, survival difference between the groups reflected R value, where an increase in R was associated with improved survival. The association of R with mortality was strengthened by adjustment in demographic variables and attenuated after adjustment to MICS. Mortality associations in accordance with R were not influenced by residual kidney function (RKF). The novel protein to phosphorus ratio score R predicts mortality in people on dialysis, probably reflecting both nutrition and inflammation state independent of RKF. The metric enables better phosphorus monitoring, although adequate dietary protein intake is ensured and may improve the prediction of outcomes in the clinical setting.

Phytoplankton community dynamics as a metrics of shrimp healthy farming under intensive cultivation

In this study, the composition and temporal dynamics of phytoplankton communities were tracked in shrimp ponds of two crops with different health status (healthy or diseased) to explore the potential relationship between phytoplankton community dynamics and/or stability and shrimp health status. Differences in phytoplankton community structures and succession patterns between the two crops were detected by non-metric multidimensional scaling and time-lag regression analysis. Although no significant difference was observed in the α-diversity between the two crops, their community dynamics differed. The turnover and mean shifts in species rank abundance and composition changes of phytoplankton community in the second crop were higher than those in the first crop. Moreover, the stability values of the first crop were significantly higher than those of the second crop. Redundancy analysis revealed that total nitrogen and nitrogen to phosphorus ratio (N/P) were correlated with the phytoplankton community composition in the first crop. In the second crop, the phytoplankton community was regulated by water temperature and dissolved oxygen (DO) in addition to nutrients. Based on linear regression, the phytoplankton community dynamic was correlated with the changes of N/P in the first crop. The DO and the sum of nitrate and nitrite (NOx) and orthophosphate (PO4-P) were the major influencing factors of phytoplankton community dynamics in the second crop. In summary, our findings indicate that the phytoplankton community dynamics may affect the shrimp health, and maintaining a stable phytoplankton community will be helpful to the healthy farming of shrimp. This study provides evidence that the phytoplankton community dynamics can serve as the metrics to evaluate the quality of rearing environment in intensive shrimp pond.

Effect of Feeding a High Calcium: Phosphorus Ratio, Phosphorous Deficient Diet on Hypophosphatemic Rickets Onset in Broilers

Recently, a P-deficient diet caused rickets in commercial chicks within three days. This study aimed to investigate the duration of onset of rickets in chicks. Data were collected from 3–11 day old chicks raised on 88 commercial farms. Male day-old Arbor Acres Plus broilers (n = 450) were studied in three trials, with three to four treatments each. Each treatment used one of the following crumbled feeds: control feed (calcium (Ca): phosphorus (P)-1.41), slightly high Ca:P feed (SHCa:P, Ca:P-2.69), high Ca:P ratio, P deficient feed (HCa:P, Ca:P-3.08), and HCa:P feed plus 1.5% dicalcium phosphate (HCa:P + DP). Each treatment had three replicates with 15 birds each. Rickets was induced by HCa:P, and cured by HCa:P + DP, confirmed by gross anatomy, gait score, serum P concentration and growth performance. Lameness was not found in control groups, whereas, observed in the HCa:P groups as early as day 2.7 on commercial farms and day 3 in experimental farm. Serum P was reduced in HCa:P (p &lt; 0.01). Bodyweight and feed intake started decreasing at day 3 on commercial farms and in all trials (p &lt; 0.01). The duration of onset of hypophosphatemic rickets in broiler chicks fed HCa:P crumbled feed is approximately three days.

Iron speciation in organic-rich shales from the Upper Triassic Yanchang Formation, Ordos Basin, Northern China: Implications for depositional environment

The iron (Fe) cycle is one of the most important marine and lacustrine geochemical cycles and is closely related to environmental redox conditions, which directly affects carbon, sulfur, phosphorus cycling. Analysis of Fe speciation (including Feox, Femag, Fecarb, and Fepy) of organic-rich shale samples provides new insights into the controversial redox conditions during the Chang 7 sedimentary period. Our results show that Fecarb and Fepy of the Chang 7 organic-rich shale are the main forms of reactive Fe pools, indicating that reactive Fe mainly existed in the form of Fe2+ in sediments. With a few exceptions, most samples fall into the ferruginous region in crossplots of Fepy/FeHR versus FeHR/FeT, indicating that pore water environments during early diagenesis were ferruginous accompanied by intermittent euxinic. Previous works examining the size of framboidal pyrite, the molar ratio of organic carbon and total phosphorus (P), and nitrogen isotope values suggest the bottom water environments conditions were oxic-suboxic accompanied by intermittent anoxic. We argue these patterns may be explained by the proximity of the redox boundary of depositional environment to the sediment–water interface during most of the Chang 7 period, with short-term fluctuations. Euxinic pore water conditions correspond to anoxic bottom water conditions and elevated total organic carbon (TOC) content, indicating that these environmental conditions would increase the flux of P diffused from sediments. As a result, lacustrine primary productivity would be elevated, creating conditions conducive to the accumulation of organic matter that is characteristic of the Chang 7 sedimentary period. This work will further our understanding of the accumulation mechanism of organic matter in the Chang 7 shale, the principal source rock for the Mesozoic oil-bearing system in the Ordos Basin.

Study on Additive Manufacturing of ABS Flame Retardant Wire

The composite flame retardant composed of Microencapsulated Red Phosphorus and aluminum hydroxide was used to study the flame retardancy of ABS wire rod for additive manufacturing. Through the detection of material oxygen index, mechanical properties and solution flow rate, the results show that when the ratio of red phosphorus and aluminum hydroxide in microcapsule is 2:1 and the addition amount is 27 phr, the LOI is 29.7, reaching UL94 V0, the tensile strength is 30.16Mpa, the elongation at break is 10.95%, the impact strength is 3.2Mpa, the bending strength is 45.5Mpa, and the solution flow rate is 6.56g/10min. The 3D printing is smooth, and the product surface is smooth and of good quality, which meets the use requirements.

Plant and soil elemental C:N:P ratios are linked to soil microbial diversity during grassland restoration on the Loess Plateau, China

Plant and soil elemental ratios of carbon (C), nitrogen (N) and phosphorus (P) play a central role in shaping the composition and structure of microbial communities. However, the relationships between plant and soil elemental C:N:P ratios and microbial diversity are still poorly understood. Here, we evaluated the effects of C:N:P ratios in plant-soil systems on microbial diversity in a chronosequence of restored grasslands (1, 5, 10, 15, 25, and 30 years since restoration) on the Loess Plateau. We found that C and N concentrations, C:N and C:P ratios in leaf, root, soil and microbial biomass, bacterial and fungal diversity (Shannon-Wiener index) gradually increased with year since grassland restoration. Microbial C:N:P ratios ranged from 17.8:4.5:1 to 24.3:6.6:1, and C:P ratio increased from 17.8:1 at the 1-year site to 24.3:1 at the 30-year site, indicating the increasing P limitation for soil microorganisms during grassland development. Soil microbial diversity increased with root, soil, and microbial C and N concentrations, and decreased with P concentration (p < 0.05). Structural equation modeling indicated that soil and microbial C:N and N:P ratios had the greatest influences on soil bacterial and fungal diversity, and elemental C:N:P ratios had a greater effect on soil fungal than bacterial diversity. Our findings emphasize the importance of elemental C:N:P ratios on soil microbial diversity, which is critical for formulating policies for sustainable biodiversity conservation in terrestrial ecosystems.

Disentangling drivers of soil microbial nutrient limitation in intensive agricultural and natural ecosystems

Characterized by continuous chemical fertilization, intensive agriculture generally reduces soil ecoenzymatic activities and nutrient mineralization, as well as alters the biomass production and microbial community composition. Soil acidification poses serious threats to the sustainable development of intensive agriculture. However, the mechanism of nutrient cycling and metabolism of soil microorganisms in response to soil acidification in intensive agriculture remains unclear. Herein, we studied the variations in ecoenzymatic stoichiometry of soil β-glucosidase (BG), cellobiohydrolase (CBH), N-acetylglucosaminidase (NAG) and acid phosphatase (AP) under different land use types and pH gradients of tea garden soils. The results revealed that natural forest and cropland soils had significantly higher BG and CBH activities than tea garden soils. Soil BG and CBH activities displayed significant positive correlations with soil pH, total nitrogen (TN) and phosphorus (TP), while soil NAG activity was significantly associated with nitrate nitrogen, total carbon (TC), TN, carbon: phosphorus (C:P) and nitrogen: phosphorus (N:P) ratios. Soil AP activity showed significant negative associations with pH, TP and C:N ratio, but was significantly positively correlated with TC, TN, C:P and N:P ratios. Enzyme vector model revealed that soil microorganisms are limited by P (enzyme vector angle >45°) regardless of land use types. Compared to natural forest soils, the P limitation of microorganisms in tea garden soils became increasingly serious with a decreasing pH gradient, as indicated by the significant increase in enzyme vector angle. Thus, the overall ecoenzymatic stoichiometry was shifted by soil pH. In summary, higher pH increased BG activity and decreased AP activity, but had no significant effect on NAG activity, suggesting co-limitation of soil microorganisms by C and P in this area. This study provides novel insights into the effect of soil acidification on ecoenzymatic stoichiometry, and also highlights the stoichiometric and energy limitations on the metabolism of soil microorganisms in agricultural ecosystems.

Water quality, phytoplankton composition and microcystin concentrations in Kisumu Bay (Kenya) of Lake Victoria after a prolonged water hyacinth infestation period

AbstractThe production of phytoplankton (algal) toxins and their control is of concern because of the need to reduce their negative impacts on water quality and facilitate effective management of algal blooms. The present study was conducted between September 2017 to May 2018, focusing on Kisumu Bay in the Kenyan portion of Lake Victoria, in order to establish the magnitude of potential impacts on phytoplankton composition and microcystin following a prolonged presence of water hyacinth coverage between 2013 and 2018 within the gulf, with an estimated coverage range varying between 644 and 1224 ha. Triplicate samples of physico‐chemical parameters, nutrients, phytoplankton, chlorophyll‐a and algal toxins (N = 88) were collected at eleven sampling sites to determine their spatio‐temporal variability. The main identified algal taxa comprised Cyanophyceae, Bacillariophyceae, Chlorophyceae, Euglenophyceae, Zygnematophyceae and Dinophyceae. The most dominant algal species were Microcystis aeruginosa (25%), Merismopedia spp. (23%) and Anabaena flos‐aquae (16%). Enzyme‐linked immunosorbent assay (ELISA) technique was used to determine microcystin (MC) toxins in the water. Mean MC‐LR and MC‐YR concentrations were significantly correlated (R2 = 0.972), exceeding WHO standards at three sampling sites (Coca Cola, 2.84 ± 4.76; Kisumu pier, 1.78 ± 1.87; Midpoint, 1.44 ± 2.71 μg/L MC–LR). There were significant temporal variations (p &lt; .05) in the SRP, TN, NO3‐N, NO2‐N, NH4‐N, SiO2‐Si, MC‐LR, MC‐YR, dissolved oxygen (DO), total dissolved and suspended solids (TDS; TSS), turbidity, electrical conductivity, Secchi depth, temperature and pH levels. The water depth, TP and DO also vary spatially. The nitrogen to phosphorus concentration ratios differed from the expected N:P ratio of 16:1, indicating a highly eutrophic status. The disproportionate ratio of total phosphorus and total nitrogen in the bay may be responsible for the enhanced cyanobacterial blooms it exhibits. The results of the present study provide useful information and data for formulating regulations for water quality management.

Using a Commercial Gut Loading Diet to Create a Positive Calcium to Phosphorus Ratio in Mealworms (Tenebrio molitor)

Mealworms ( Tenebrio molitor ) are one of the most common feeder insects fed to exotic animals due to their high acceptance rate, larval longevity, and ease of care. Unfortunately, in their natural commercial state, they are severely deficient in calcium and can predispose exotic animals to hypocalcemia and related metabolic disorders. Gut loading insects with calcium-rich diets is recommended to improve the insects’ nutrient content and to achieve a calcium to phosphorus (Ca:P) ratio of at least 1:1; however, there are few commercial gut loading diets specifically made for mealworms. In this study, mealworms were gut loaded with a newly developed high calcium mealworm diet for 0, 24, or 48 hours. All mealworms were analyzed for dry matter (DM), moisture, calcium, and phosphorus at each time point. Due to the dry nature of the diet, moisture content decreased over time (mean moisture content= 75%, 70%, and 66% at time 0, 24, and 48 hrs, respectively). Calcium content was significantly increased by 24 hrs (p=0.011) and remained elevated at 48 hrs for both the as fed and DM measurements (median calcium DM: 0.07%, 3.5%, and 3.7% at 0, 24, and 48 hrs, respectively). Ca:P ratios were also significantly increased for both the 24 hr (p=0.028) and 48 hr (p= 0.028) periods (median Ca:P DM:1:20, 3.2:1, and 3.6:1 at 0, 24, and 48 hrs, respectively). This data supports the diet’s claim to provide a positive Ca:P ratio in mealworms fed the diet for 48 hours.

Clinical progression of cats with early-stage chronic kidney disease fed diets with varying protein and phosphorus contents and calcium to phosphorus ratios.

BackgroundDietary protein and phosphorus (P) restriction is the mainstay for nutritional management of chronic kidney disease (CKD). However, adequate restriction levels for cats with early CKD remain unclear.ObjectivesTo investigate responses in cats with early CKD to varying dietary protein, P, and calcium (Ca) : P ratio.AnimalsNineteen research colony cats with International Renal Interest Society stages 1‐2 CKD.MethodsIn an opportunistic longitudinal case study, cats were fed a low protein (59 g/Mcal), low P (0.84 g/Mcal) dry diet (LP‐LP; Ca : P = 1.9) for 18 months and later transitioned onto a moderate protein (76‐98 g/Mcal), moderate P (1.4‐1.6 g/Mcal) dry‐wet diet regimen (MP‐MP; Ca : P = 1.4‐1.6) for 22 months. Fold‐changes in serum creatinine, total Ca (tCa) and P (primary outcomes) and fibroblast growth factor 23 (FGF23) were assessed by linear‐mixed models.ResultsWhile feeding LP‐LP, mean serum creatinine decreased (0.87‐fold, 95% confidence interval [CI] 0.81, 0.93, P < .001) to within reference range after 6 months, while increases in total Ca (tCa; 1.16‐fold, 95% CI 1.11, 1.22, P < .001) and FGF23 (2.72‐fold, 95% CI 1.72, 4.31, P < .001), but not in P (1.03‐fold, 95% CI 0.945, 1.124, P = .94), were observed after 17 months. On MP‐MP, mean creatinine, tCa and P remained within reference ranges and did not significantly change (P = .11, P = .98, and P = 1, respectively), while FGF23 significantly decreased (0.58‐fold, 95% CI 0.36, 0.95, P = .02) after 22 months.Conclusions and Clinical ImportanceCats with early CKD developed hypercalcemia after long‐term feeding of a highly P‐restricted diet. Increasing dietary P and reducing Ca : P ratio maintained renal markers, while improving Ca‐P balance. Cats with early CKD could benefit from moderately protein‐ and P‐restricted diets.

Effect of Zr(IV) to phosphorus ratio on U(VI) adsorption by diethylenetriamine-pentamethylene phosphate Zr(IV) hybrids

Abstract In this work, diethylenetriamine pentamethylenephosphonic acid (DTPMP) was ultilized into preparing of Zr(IV) organophosphates hybrids (Zr-DTPMP-x, x was the molar ratio of Zr(IV)/DTPMP in the synthetic process, x = 0.5, 1, 2, and 3) using a hydrothermal method. The physical and chemical properties of Zr-DTPMP-x were characterized by SEM&amp;EDS, FT-IR, XRD, Zeta potential, XPS, TGA and contact angle analysis. Moreover, the adsorptive performances of Zr-DTPMP-x for U(VI) were investigated. The adsorption results showed that the optimum molar ratio of Zr(IV) to phosphine, pH, equilibrium time, and dosage was 0.5, 4.0, 180 min, and 10 mg, respectively. Besides, the adsorption of U(VI) was in accordance with the pseudo-second-order kinetic model and Sips isothermal model. Moreover, the adsorption capacity determined by Sips isothermal model was 181.34 mg g−1 for Zr-DTPMP-0.5. Furthermore, the adsorptive selectivity of Zr-DTPMP-0.5 for U(VI) was superior than the others. Zr-DTPMP-0.5 may be a powerful candidate for diminishing the contamination of U(VI).

БІОХІМІЧНИЙ ПРОФІЛЬ ТА АКТИВНІСТЬ ЕНЗИМІВ СИРОВАТКИ КРОВІ КУРЕЙ ЗА ЗМІНИ ВИСОТИ РОЗТАШУВАННЯ КЛІТКОВИХ БАТАРЕЙ

In the conditions of industrial poultry farming, the body of hens is constantly exposed to numerous technological stressors, the least studied of which are long-term, which can cause the development of chronic stress. One such technological stressor may be to increase the tier of cage equipment, which is a method of resource conservation in egg poultry and is often used by producers to obtain more eggs from 1 m2 of poultry area. Increasing the level of cage equipment involves the location of the cage in 12 and even 15 tiers, forming 4–5 floors. This allows to increase the concentration of poultry in the poultry house by 4-5 times, compared with 3-tier cage batteries, and 8-10 times – compared to the floor method of keeping. For this livestock in one poultry house can reach 590 thousand hens. However, there are no data on the impact of such a keeping method on the physiological state of hens, and the current rules of VNTP-APK-04.05. for keeping hens in cages designed for 1-3-tier cage batteries. The aim of this work was to study the physiological state of the hen’s body based on the analysis of the biochemical profile and the activity of serum enzymes in their blood depending on the height of the cage batteries. For this purpose, in the conditions of a modern complex for the production of food eggs in one poultry house, 4 groups of hens were formed, each of which was kept on a separate floor-analogue in terms of area and cage equipment. Each floor was equipped with 3-tier cage batteries “Big Dutchman” (Germany), consisting of 1176 cages. It was found that increasing the layering of cage equipment does not have a negative impact on the hen’s body. So, for keeping hens in cages of multilevel cages batteries located on 2-4 floors (4-12 tiers), the biochemical status and activity of their blood serum enzymes were within the physiological norm. In hens kept in cages of the 3rd floor there was an increase, within the physiological norm, aspartate aminotransferase by 7.9%, and in hens of the 2nd floor there was an increase in glucose by 4.6-6.5%, creatinine – by 2.4%, phosphorus by 8.8-9.6%, as well as an increase in the activity of aspartate aminotransferase by 2.2-10.2% and lactate dehydrogenase – by 11.2%. Whereas, when keeping hens in cages of a multi-tiered cage battery on the first floor, there was an increase in glucose levels by 60.5-71.0% (10.9% ˃ of normal), creatinine – by 9.7-12.3% (4.8 % ˃ norm), phosphorus – 82.6–100.0% (23.6% ˃ norm), a decrease in the ratio of calcium and phosphorus by 46.7-50.0% (46.7% ˂ norm), which was confirmed by an increase in alkaline phosphatase activity by 22.3-27.0% (3.4% ˃ normal), as well as an increase in aspartate aminotransferase activity by 3.2-13.8% (1.7% ˃ normal), lactate dehydrogenase – by 48.5-65.1% (10.8% ˃ of normal) and gamma-glutamyltransferase – by 16.4-20.6%. Thus, the main effects of chronic stress caused by keeping hens in the cells of the lower floor of a multi-tiered cage battery are reflected in the biochemical parameters of their serum, namely increased glucose, creatinine, enzyme activity and change of the ratio of calcium and phosphorus.

Diversity and abundance of diazotrophic communities of seagrass Halophila ovalis based on genomic and transcript level in Daya Bay, South China Sea.

Seagrass ecosystems are among the most productive marine ecosystems, and diazotrophic communities play a crucial role in sustaining the productivity and stability of such ecosystems by introducing fixed nitrogen. However, information concerning both total and active diazotrophic groups existing in different compartments of seagrass is lacking. This study comprehensively investigated the diversity, structure, and abundance of diazotrophic communities in different parts of the seagrass Halophila ovalis at the DNA and RNA level from clone libraries and real-time quantitative PCR. Our results indicated that nearly one-third of existing nitrogen-fixing bacteria were active, and their abundance might be controlled by nitrogen to phosphorus ratio (N:P). Deltaproteobacteria and Gammaproteobacteria were dominant groups among the total and active diazotrophic communities in all samples. These two groups accounted for 82.21% and 70.96% at the DNA and RNA levels, respectively. The genus Pseudomonas and sulfate-reducing bacteria (genera: Desulfosarcina, Desulfobulbus, Desulfocapsa, and Desulfopila) constituted the significant fraction of nitrogen-fixing bacteria in the seagrass ecosystem, playing an additional role in denitrification and sulfate reduction, respectively. Moreover, the abundance of the nitrogenase gene, nifH, was highest in seawater and lowest in rhizosphere sediments from all samples. This study highlighted the role of diazotropic communities in the subtropical seagrass ecosystem.

Tracing Nutrients and Organic Matter Changes in Eutrophic Wenchang (China) and Oligotrophic Krka (Croatia) Estuaries: A Comparative Study

Estuaries modify the concentration and composition of riverine nutrients and organic matter (OM), which eventually determine the riverine flux effect to coasts. Nutrients, organic carbon (OC), pigments, and amino acids (AAs) from the samples collected in the eutrophic Wenchang River Estuary (WRE) in China and the oligotrophic Krka River Estuary (KRE) in Croatia were analyzed in order to have a better understanding of how estuaries regulate terrestrial materials. We found a clear increase of dissolved inorganic nitrogen (DIN) concentration and its subsequent decrease due to the removal of DIN (over 100 μM) in the WRE, whereas DIN showed minor variation lengthwise in the KRE, i.e., with the salinity changes, ranging between 1.0 and 5.8 μM. The elevated algae-derived OC, dissolved organic nitrogen, and particulate AAs nitrogen suggest that the OM assimilation may explain approximately one-third of the DIN removal in the WRE, whereas in the oligotrophic KRE, such inorganic to organic transformation is not likely to be significant. Due to the prominent estuarine nitrogen removal/assimilation process, DIN/dissolved inorganic phosphorus (DIP) ratio was as high as 425 in the upper WRE under strong riverine influence, but it declined to as low as 5.4 at the mouth of WRE, that is even lower than DIN/DIP ratio at the mouth of oligotrophic KRE (12). When compared with other rivers worldwide, the Wenchang River showed high nutrients and organic carbon yields. Given the contrasting estuarine process (e.g., DIN removal) between the KRE and the WRE, apparent high nutrient yield from eutrophic rivers should be viewed with caution in ocean studies as the final impact to coastal zone could be similar to the oligotrophic rivers like the KRE.