The influence of biochar from animal and plant on the transformation of phosphorus during paper mill sludge composting

Biochar has effect on phosphorus adsorption, release, and transformation. This study compared the influence of biochar derived from animal (AB) and plant (PB) during paper mill sludge composting. Results indicated AB not only accelerated sludge decomposition but also had significantly higher levels of available phosphorus (AP) than PB and CK (no biochar), with AP contents in the order of AB > PB > CK. Compared to CK, AB was found to increase the relative abundance of thermophilic bacteria, and PB diversified the microbial community. Based on Pearson and RDA results, TOC/TN ratio (C/N) and organic matter (OM) explained above 50% of the variance in microbial community and phosphorus fractions. Thermophilic bacteria with high levels of OM and C/N promoted the conversion among labile and moderately labile organic phosphorus, moderately labile inorganic phosphorus, and AP. Biochar could enhance the AP conversion pathway, leading to increased levels of AP.

Factors regulating interaction among inorganic nitrogen and phosphorus species, plant uptake, and relevant cycling genes in a weakly alkaline soil treated with biochar and inorganic fertilizer

To highlight how biochar affects the interaction between inorganic nitrogen species (ammonium nitrogen, nitrate nitrogen, and nitrite nitrogen: NH4+-N, NO3¯-N, and NO2¯-N) and phosphorus species (calcium phosphate, iron phosphate, and aluminum phosphate: CaP, FeP and AlP) in soil and plant uptake of these nutrients, walnut shell (WS)- and corn cob (CC)-derived biochars (0.5 %, 1 %, 2 %, and 4 %, w/w) were added to a weakly alkaline soil, and then Chinese cabbages were planted. The results showed that the changes in soil inorganic nitrogen were related to biochar feedstock, pyrolysis temperature, and application rate. For soil under the active nitrification condition (dominant NO3¯-N), a significant decrease in the NH4+-N/NO3¯-N ratio after biochar addition indicates enhanced nitrification (excluding WS-derived biochars at 2 % and 4 %), which can be explained by the most positive response of ammonia-oxidizing archaeal amoA to biochar addition. The CC-derived biochar more effectively enhanced soil nitrification than WS-derived biochar did. The addition of 4 % of biochars significantly increased soil inorganic phosphorus, and the addition of CC-derived biochars more effectively increased Ca2P than WS-derived biochars. Biochars significantly decreased plant uptake of phosphorus, while generally had little influence on plant uptake of nitrogen. Interestingly, NO2¯-N in soil significantly positively correlated with total phosphorus in both soil and plant, and significantly negatively correlated with phoC, indicating that a certain degree of NO2¯-N accumulation in soil slightly facilitated plant uptake of phosphorus but inhibited phoC-harboring bacteria. The NO3¯-N in soil significantly positively correlated with Ca2P and Ca8P, while the NH4+-N/NO3¯-N ratio significantly negatively correlated with Ca10P and FeP, indicating that the enhanced nitrification seemed to facilitate the change in phosphorus to readly available ones. This study will help determine how to scientifically and rationally use biochar to regulate inorganic nitrogen and phosphorus species in soil and plant uptake of these nutrients.

Dietary non-phytate phosphorus requirements for optimal productive and reproductive performance, and egg and tibial quality in egg-type duck breeders

Optimal dietary non-phytate phosphorus (NPP) is essential in poultry to maximise productive and reproductive performance, along with indices of egg and bone quality. This study aimed to establish the NPP requirements of egg-type duck breeders aged from 54 to 80 weeks on the following traits: egg production, egg incubation, egg quality, tibial characteristics, reproductive organ, plasma indices, and the expression of genes related to phosphorus absorption. Longyan duck breeders aged 54 weeks (n = 300) were randomly allotted to five treatments, each containing six replicates of 10 individually caged birds. Birds were fed corn-soybean meal-based diets containing 0.18, 0.25, 0.32, 0.38, and 0.45% NPP/kg for 27 weeks. The tested dietary NPP levels did not affect egg production or egg quality indices. The hatchling weight of ducklings increased (quadratic, P < 0.01) as dietary NPP level increased, and the highest value occurred with 0.25% NPP. The number of large yellow follicles (LYF), and the relative weights of LYF and ovary showed linear and quadratic responses to dietary NPP levels; the lowest number and relative weight of LYF occurred with 0.38% NPP, and the lowest ovarian weight was obtained with 0.25% NPP. There were no differences in tibial length, breaking strength, and mineral density in response to dietary NPP levels. In contrast, tibial content of Ca increased (linear, P < 0.01) with dietary NPP levels increasing from 0.18 to 0.45%, and the tibial content of P increased at 0.32% NPP and the higher dietary NPP levels. Plasma concentration of P showed a quadratic (P < 0.05) response to the dietary NPP levels, where the highest value was seen at 0.38% NPP. In conclusion, dietary NPP levels from 0.18 to 0.45% had no effects on egg production, and egg and tibial quality of duck breeders. The duck breeders fed a diet with 0.25% NPP showed the highest hatchling weight of their offspring, while those fed 0.38% NPP had the lowest number and relative weight of LYF. These results indicated that the diet with 0.25% NPP can be used in egg-type duck breeders to improve the hatchling weight of their offspring, without adverse effects on their productivity. The regression model indicated that the maximal hatchling weight of ducklings was obtained from duck breeders fed the diet with 0.30% NPP.

Phosphorus and its solubility in aerosols from continental and marine sources in the sea areas near China: Results from a 40-day cruise mission in late spring

Accurate assessments of soluble phosphorus (P) in aerosol particles are essential to understand the atmospheric nutrients supply to the marine ecosystem. We quantified total P (TP) and dissolved P (DP) in the aerosol particles collected in the sea areas near China in a cruise mission from May 1 to June 11, 2016. The overall concentrations of TP and DP were 3.5-99.9 ng m^-3 and 2.5-27.0 ng m^-3, respectively. When the air originating from the desert areas, TP and DP were 28.7-99.9 ng m^-3 and 10.8-27.0 ng m^-3, respectively, and P solubility was 24.1-54.6 %. When the air influenced mainly by anthropogenic emissions from eastern China, TP and DP were 11.7-12.3 ng m^-3 and 5.7-6.3 ng m^-3, respectively, and P solubility was 46.0-53.7 %. More than half of the TP and more than 70 % of the DP were from pyrogenic particles, with a considerable DP converted via aerosol acidification after the particles met humid marine air. On average, aerosol acidification promoted the fractional solubility of dissolved inorganic P (DIP) to TP from 22 % to 43 %. When the air originating from the marine areas, TP and DP were 3.5-22.0 ng m^-3 and 2.5-8.4 ng m^-3, respectively, and P solubility was 34.6-93.6 %. About one-third of the DP was from biological emissions in organic forms (DOP), leading to higher solubility than in the particles from continental sources. These results reveal the dominance of inorganic P in TP and DP from the desert and anthropogenic mineral dust and the significant contribution of organic P from marine sources. The results also indicate the necessity to treat aerosol P carefully according to different sources of the aerosol particles and atmospheric processes the particles experience in assessing aerosol P input to seawater.

Adsorption of inorganic and organic phosphorus onto polypyrrole modified red mud: Evidence from batch and column experiments

The ubiquitous presence of inorganic and organic phosphorus in wastewater and natural water bodies has deteriorated the water environment qualities and exerted significant influences on ecosystems. In this study, an effective polypyrrole modified red mud adsorbent (PRM) was optimized for the adsorptive removal of inorganic and organic phosphorus from aqueous solutions. The addition of ferric chloride and pyrrole was optimized for complete oxidation and modification of polypyrrole onto red mud. Kinetic studies illustrated that the adsorption progress was accomplished by physical and chemical adsorption. The experimental data of the optimized PRM were described well by Langmuir isotherm, and the equilibrium adsorption capacity was 32.9 and 54.7 mg/g for inorganic and organic phosphorus, respectively. The PRM showed commendable adsorption performance despite the pH conditions ranging from 3 to 11. From the effect of ion strength and X-ray photoelectron spectroscopy (XPS) tests, we found that ligand exchange is the main mechanism of orthophosphate adsorption onto PRM, while electrostatic attraction played an important role in organic phosphorus adsorption. The adsorption performance from column studies showed that the velocity of flow influenced the breakthrough time of the column but the initial concentration had minor impacts. This study would extend the potential application of polypyrrole modified red mud, acting as an efficient adsorbent for inorganic and organic phosphorus adsorption in water treatment.

Phytic acid accumulation in plants: Biosynthesis pathway regulation and role in human diet

Phytate or phytic acid (PA), is a phosphorus (P) containing compound generated by the stepwise phosphorylation of myo-inositol. It forms complexes with some nutrient cations, such as Ca, Fe and Zn, compromising their absorption and thus acting as an anti-nutrient in the digestive tract of humans and monogastric animals. Conversely, PAs are an important form of P storage in seeds, making up to 90% of total seed P. Phytates also play a role in germination and are related to the synthesis of abscisic acid and gibberellins, the hormones involved in seed germination. Decreasing PA content in plants is desirable for human dietary. Therefore, low phytic acid (lpa) mutants might present some negative pleiotropic effects, which could impair germination and seed viability. In the present study, we review current knowledge of the genes encoding enzymes that function in different stages of PA synthesis, from the first phosphorylation of myo-inositol to PA transport into seed reserve tissues, and the application of this knowledge to reduce PA concentrations in edible crops to enhance human diet. Finally, phylogenetic data for PA concentrations in different plant families and distributed across several countries under different environmental conditions are compiled. The results of the present study help explain the importance of PA accumulation in different plant families and the distribution of PA accumulation in different foods.

Molecular responses to inorganic and organic phosphorus sources in the growth and toxin formation of Microcystis aeruginosa

Toxic cyanobacteria bloom is a ubiquitous phenomenon worldwide in eutrophic lakes or reservoirs. Microcystis, is a cosmopolitan genus in cyanobacteria and exists in many different forms. Microcystis aeruginosa (M. aeruginosa) can produce microcystins (MCs) with strong liver toxicity during its growth and decomposition. Phosphorus (P) is a typical growth limiting factor of M. aeruginosa. Though different forms and concentrations of P are common in natural water, the molecular responses in the growth and MCs formation of M. aeruginosa remain unclear. In this study, laboratory experiments were conducted to determine the uptake of P, cell activity, MCs release, and related gene expression under different concentrations of dissolved inorganic phosphorus (DIP) and dissolved organic phosphorus (DOP). We found that the growth of M. aeruginosa was promoted by increasing DIP concentration but coerced under high concentration (0.6 and 1.0 mg P/L) of DOP after P starvation. The growth stress was not related to the alkaline phosphatase activity (APA). Although alkaline phosphatase (AP) could convert DOP into algae absorbable DIP, the growth status of M. aeruginosa mainly depended on the response mechanism of phosphate transporter expression to the extracellular P concentration. High-concentration DIP promoted MCs production in M. aeruginosa, while high-concentration DOP triggered the release of intracellular MCs rather than affecting MCs production. Our study revealed the molecular responses of algal growth and toxin formation under different P sources, and provided a theoretical basis and novel idea for risk management of eutrophic lakes and reservoirs.

Dynamics of phosphorus fractions and potential bioavailability along soil profiles from seasonal-flooding wetlands in a Chinese estuary

Soil phosphorus fractions in wetland ecosystems have received increasing attention due to its high eutrophication risks. Soil samples were collected to 40 cm depth in three sampling seasons to investigate the seasonal dynamics of organic and inorganic phosphorus fractions, bioavailability, and relationship between those and soil properties in a seasonal-flooding wetland in the Yellow River Estuary. The results showed that inorganic phosphorus (IP) and organic phosphorus (OP) contents exhibited much higher levels in the top 10 cm soils, and declined along soil profiles in spring. IP kept constant along soil profiles in fall, while OP decreased in summer and fall. They were greatly affected by water content (WC), pH, Cl^-/SO₄^2-, soil organic matter (SOM), and electrical conductivity (EC). Middle labile organic phosphorus (MLOP) and non-labile organic phosphorus (NLOP) accounted for higher percentages of total OP in summer and fall respectively than labile organic phosphorus (LOP) in spring. MLOP and NLOP levels showed a decrease along soil profiles in spring and in spring/fall, respectively, while NLOP significantly increased with depth in summer. Ca-P was the dominant IP fraction in all soils in three sampling seasons, declined with depth in spring/fall and increased in summer. Comparatively, soluble/loosely-P(S/L-P) generally decreased with depth along soil profiles in three sampling seasons. And residual P (Res-P) kept little change with depth in spring. Fe/Al-P levels decreased firstly and then increased with depth in spring and summer. Available phosphorus and potential bioavailable phosphorus contents decreased with depth in spring and summer not in fall, and had a strong significant positive correlation with WC and SOM. Alkaline phosphatase not acid phosphatase was the key factor influencing soil MLOP levels. Generally, the fractions and bioavailability of phosphorus as well as phosphatase in this region were affected by soil depth, sampling seasons, and soil properties (e.g., WC, pH, Cl^-/SO₄^2-, SOM, and EC).

Responses of Corpuscles of Stannius to intra-peritoneal vitamin-D3 administration in teleost Labeo rohita (Hamilton, 1822) reared in water with two different levels of calcium concentration

This study assessed the responses of vitamin-D3 intraperitoneally injected to Rohu, Labeo rohita @ of 0 IU/kg bw (only solvent), 100 IU/kg bw and 500 IU/kg bw reared in 20 and 40 ppm of calcium (Ca) enriched water. The cellular changes in Corpuscles of Stannius (CS) gland, serum Ca, and inorganic phosphate (Pi) level were analysed up to the 60th day. Rohu administered with 100 IU/kg bw D3 and exposed to 40 ppm Ca-rich water exhibited notable hyperplasia of CS compared with their control groups. Notable changes with high serum Ca level (13.87 ± 0.3 mg/dl) was detected on the 5th day in fish exposed to 40 ppm Ca-rich water, while related values attained (13.74 ± 0.1 mg/dl) only after 7 days in 20 ppm Ca-rich water of 500 IU/kg bw vitamin D3 injection. Similarly, high serum Pi level (7.66 ± 0.2 mg/dl) in 40 ppm Ca injected with D3 at 500 IU/kg bw. The results demonstrated that the Ca homeostasis of Labeo rohita is influenced by intra-peritoneal vitamin D3. Progressive studies should be conducted by increasing the dose of vitamin D3 to investigate optimum dose/supplement in feed for commercially important aquaculture teleost Labeo rohita for maximum and sustainable absorption of Ca from the variable water Calcium levels to maintain Ca2+ homeostasis.

Removal of inorganic and organic phosphorus compounds from aqueous solution by ferrihydrite decoration onto graphene

Existing research on phosphorus removal from wastewater mostly focused on inorganic phosphorus while ignoring organic phosphorus, which has potential bioavailability. This study aims to provide an innovation for the development of advanced treatment material for both inorganic and organic phosphorus removal in water. In this study, ferrihydrite loaded on the graphene oxide (FeOOH-GO) composite adsorbent was synthesized by surface precipitation method, and its ability to remove both phosphate and diazinon as forms of inorganic and organic phosphorous from water was investigated. Characterization of the loaded composite using X-ray diffraction (XRD), scanning electron microscope (SEM), and Fourier transform-infrared spectroscopy (FTIR) indicated that FeOOH was successfully loaded onto graphene. The results of batch adsorption experiments showed that the adsorbent could remove both inorganic and organic phosphorus compounds simultaneously from water. When FeOOH content is 40%, the equilibrium adsorption amount of FeOOH-GO composite adsorbent for phosphate and diazinon was 5.81 and 23.20 mg g^-1, respectively. Environmental parameters such as pH and initial concentration have important influence on phosphorus removal by FeOOH-GO composite adsorbent and the removal efficiency of the inorganic and organic phosphorus from water decreases by increasing the initial concentration of phosphate and diazinon and the pH. It was concluded that the FeOOH-GO composite adsorbent has great potential to remove both inorganic and organic phosphate simultaneously from contaminated water.

Enhanced removal of tris(2-chloroethyl) phosphate using a resin-based nanocomposite hydrated iron oxide through a Fenton-like process: Capacity evaluation and pathways

The effective removal of organophosphorus compounds (OPs) effectively from water environment remains an important but challenging task. In this study, a resin-based nanocomposite of hydrated iron oxide (HD1) was used as Fenton-like catalyst for effectively catalyzing the decomposition of hydrogen peroxide to degrade tris(2-chloroethyl) phosphate (TCEP). The results showed that HD1 was successfully prepared, which had great versatility, catalytic performance and adsorption capacity. Besides, HD1/H₂O₂ was capable of degrading TCEP completely with less than 0.2 mg/L of inorganic phosphorus (IP) in the effluent at the initial TCEP of 38 mg/L, pH = 4, H₂O₂ dosage of 20 mM, and the K_obs could result in about 1.0530 min^-1 under identical conditions. More attractively, inorganic ions (i.e., Cl-, CO₃²-, SO₄²-, NO₃-, HCO₃-, Ca²⁺, and Mg²⁺) exhibited moderate effect on TCEP degradation. The negative effect of natural organic matters (NOM) (i.e., HA) on the degradation of TCEP was responsible for competition for the active oxygen species. Combined with electron paramagnetic resonance (EPR) spectra, X-ray photoelectron spectroscopy (XPS) and other analytical methods and radical quenching experiments, the possible removal process of TCEP was discussed, including two processes of oxidative degradation and immobilization of IP. Besides, hydroxyl radicals (•OH) was the key active species that contributed to TCEP degradation through hydroxylation-oxidation and C-O bond cracking, and specificity adsorption of HFO on IP was revealed. Furthermore, the results showed that HD1 had desirable acid and alkali resistance. In the continuous running fixed bed column experiment, HD1 showed a satisfactory performance in cycle operations. This work proposed a new enhanced process for removing TCEP in water environment by HD1/H₂O₂, and the multi-functional material, HD1 was promising in treatment of water containing organic phosphorus pollutants. This will be believed that this study will provide new ideas and new materials for the treatment of organic phosphorus-based organic pollutants, and lay the foundation for further deepening and expanding the application of adsorption resins in the field of water pollution control.

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 (TP_aq) 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-P_aq 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 TP_aq 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 (TP_mx) is considered (TP_mx was >800 mg/L in this work).

The arbuscular mycorrhizal fungus Rhizophagus irregularis MUCL 41833 increases the phosphorus uptake and biomass of Medicago truncatula, a benzo[a]pyrene-tolerant plant species

The accumulation of phosphorus (P) in plants increases their biomass and resistance/tolerance to organic pollutants. Both characteristics are mandatory for the utilization of plants in phytoremediation. Arbuscular mycorrhizal (AM) fungi improve plant P nutrition, and thus growth. However, only a few studies have focused on the dynamics of inorganic P (Pi) uptake in AM fungal-colonized plants in the presence of organic pollutants. Indeed, most of the results so far were obtained after harvesting the plants, thus by evaluating P concentration and content at a single time point. Here, we investigated the effects of the AM fungus Rhizophagus irregularis MUCL 41833 on the short-term Pi uptake dynamics of Medicago truncatula plants grown in the presence of benzo[a]pyrene (B[a]P), a polyaromatic hydrocarbon (PAH) frequently found in polluted soils. The study was conducted using a non-destructive circulatory semi-hydroponic cultivation system to investigate the short-term Pi depletion from a nutrient solution and as a corollary, the Pi uptake by the AM fungal-colonized and non-colonized plants. The growth, P concentration, and content of plants were also evaluated at harvest. The presence of B[a]P neither impacted the development of the AM fungus in the roots nor the plant growth and Pi uptake, suggesting a marked tolerance of both organisms to B[a]P pollution. A generally higher Pi uptake coupled with a higher accumulation of P in shoots and roots was noticed in AM fungal-colonized plants as compared to the non-colonized controls, irrespective of the presence or absence of B[a]P. Therefore, fungal-colonized plants showed the best growth. Furthermore, the beneficial effect provided by the presence of the AM fungus in roots was similar in presence or absence of B[a]P, thus opening the door for potential utilization in phytomanagement of PAH-polluted soils.

Ocean acidification: One potential driver of phosphorus eutrophication

Harmful algal blooms which may be limited by phosphorus outbreak increases currently and ocean acidification worsens presently, which implies that ocean acidification might lead to phosphorus eutrophication. To verify the hypothesis, oxic sediments were exposed to seawater with different pH 30days. If pH was 8.1 and 7.7, the total phosphorus (TP) content in sediments was 1.52±0.50 and 1.29±0.40mg/g. The inorganic phosphorus (IP) content in sediments exposed to seawater with pH8.1 and 7.7 was 1.39±0.10 and 1.06±0.20mg/g, respectively. The exchangeable phosphorus (Ex-P) content in sediments was 4.40±0.45 and 2.82±0.15μg/g, if seawater pH was 8.1 and 7.7. Ex-P and IP contents in oxic sediments were reduced by ocean acidification significantly (p<5%). The reduced phosphorus in sediments diffused into water, which implied that ocean acidification was one potential facilitator of phosphorus eutrophication in oxic conditions.

Physiological and comparative proteome analyses reveal low-phosphate tolerance and enhanced photosynthesis in a maize mutant owing to reinforced inorganic phosphate recycling

BACKGROUND

The low-phosphate-tolerant maize mutant Qi319-96 was obtained from Qi319 through cellular engineering. To elucidate the molecular mechanisms underlying the low-phosphate tolerance of this mutant, we performed comparative proteome analyses of the leaves of Qi319-96 and Qi319 under inorganic phosphate (Pi)-sufficient and Pi-deficient conditions.

RESULTS

Low-phosphorus levels limit plant growth and metabolism. Although the overall phosphorus contents of shoots were not significantly different between Qi319 and Qi319-96, the Pi level of Qi319-96 was 52.94 % higher than that of Qi319. Under low phosphorus conditions, Qi319-96 had increased chlorophyll levels and enhanced photosynthesis. The changes in starch and sucrose contents under these conditions also differed between genotypes. The proteomic changes included 29 (Pi-sufficient) and 71 (Pi-deficient) differentially expressed proteins involved in numerous metabolic processes. Proteome and physiological analyses revealed that Qi319-96 could better remodel the lipid composition of membranes and had higher V-ATPase activity levels than Qi319 under low-phosphate starvation, which enhanced the recycling of intracellular Pi, as reflected by its increased Pi levels. Chlorophyll biosynthesis was improved and the levels, and activities, of several Calvin cycle and "CO2 pump" enzymes were greater in Qi319-96 than in Qi319, which led to a higher rate of photosynthesis under low-phosphate stress in this line compared with in Qi319.

CONCLUSIONS

Our results suggest that the increased tolerance of the maize mutant Qi319-96 to low-phosphate levels is owing to its ability to increase Pi availability. Additionally, inbred lines of maize with low-P-tolerant traits could be obtained effectively through cellular engineering.

Phosphorus content as a function of soil aggregate size and paddy cultivation in highly weathered soils

Red soils are the major land resource in subtropical and tropical areas and are characterized by low phosphorus (P) availability. To assess the availability of P for plants and the potential stability of P in soil, two pairs of subtropical red soil samples from a paddy field and an adjacent uncultivated upland were collected from Hunan Province, China. Analysis of total P and Olsen P and sequential extraction was used to determine the inorganic and organic P fractions in different aggregate size classes. Our results showed that the soil under paddy cultivation had lower proportions of small aggregates and higher proportions of large aggregates than those from the uncultivated upland soil. The portion of >2-mm-sized aggregates increased by 31 and 20 % at Taoyuan and Guiyang, respectively. The total P and Olsen P contents were 50-150 and 50-300 % higher, respectively, in the paddy soil than those in the upland soil. Higher inorganic and organic P fractions tended to be enriched in both the smallest and largest aggregate size classes compared to the middle size class (0.02-0.2 mm). Furthermore, the proportion of P fractions was higher in smaller aggregate sizes (<2 mm) than in the higher aggregate sizes (>2 mm). In conclusion, soils under paddy cultivation displayed improved soil aggregate structure, altered distribution patterns of P fractions in different aggregate size classes, and to some extent had enhanced labile P pools.

Quantitative physicochemical analysis of acid-base balance and clinical utility of anion gap and strong ion gap in 806 neonatal calves with diarrhea

BACKGROUND

Acid-base abnormalities in neonatal diarrheic calves can be assessed by using the Henderson-Hasselbalch equation or the simplified strong ion approach which use the anion gap (AG) or the strong ion gap (SIG) to quantify the concentration of unmeasured strong anions such as D-lactate.

HYPOTHESIS/OBJECTIVES

To determine and compare the clinical utility of AG and SIG in quantifying the unmeasured strong anion charge in neonatal diarrheic calves, and to examine the associations between biochemical findings and acid-base variables by using the simplified strong ion approach. We hypothesized that the SIG provides a more accurate prediction of unmeasured strong anions than the AG.

ANIMALS

Eight hundred and six neonatal diarrheic calves admitted to a veterinary teaching hospital.

METHODS

Retrospective study utilizing clinicopathologic findings extracted from medical records.

RESULTS

Hyperphosphatemia was an important predictor of venous blood pH. Serum inorganic phosphorus and plasma D-lactate concentrations accounted for 58% of the variation in venous blood pH and 77% of the variation in AG and SIG. Plasma D- and total lactate concentrations were slightly better correlated with SIG (rs = -0.69; -0.78) than to AG (rs = 0.63; 0.74).

CONCLUSIONS AND CLINICAL IMPORTANCE

Strong ion gap is slightly better at quantifying the unmeasured strong anion concentration in neonatal diarrheic calves than AG. Phosphorus concentrations should be included as part of the calculation of Atot when applying the simplified strong ion approach to acid-base balance to critically ill animals with hyperphosphatemia.

Matrix-bound phosphine and phosphorus fractions in surface sediments of Arctic Kongsfjorden, Svalbard: effects of glacial activity and environmental variables

The surface sediments were collected from the glacial bay (GLAC), the central basin (CENTR) and their transition area (TRANS) along the fjord Kongsfjorden axis on Svalbard, Arctic, and matrix-bound phosphine (MBP), phosphorus fractions and alkaline phosphatase activity (APA) were analyzed. MBP was found in all the sediments with the concentration range of 8.93-59.45 ng kg(-1) dw. The MBP levels in the CENTR sediments were two times higher than those in the GLAC and TRANS sediments, and the yield of phosphine (PH3) as a fraction of total phosphorus ranged from 1.78×10(-8) to 3.53×10(-8) mg PH3 mg(-1)P. The CENTR and TRANS sediments showed higher concentrations of total phosphorus (TP), organic phosphorus (OP) and APA than the GLAC sediments, indicating that glacial activity had an important effect on the spatial variability in the concentrations of MBP and phosphorus fractions. There existed a significant positive correlation (p<0.01) between MBP and seawater depths, OP, TP, APA, total organic matter, total nitrogen and total sulfur. The multiple stepwise regression model ([MBP]=16.1[OP]+18.6[APA]-26.1pH+221.3) was obtained between MBP concentrations and environmental variables. This model could be used to predict MBP levels in the sediments. Our results indicated that the production of MBP was associated with OP decomposition and microbially mediated factors in the sediments of Kongsfjorden in Arctic.