Abstract  High ammonium (NH4), arsenic (As) and boron (B) concentrations are found in aquifers worldwide and are often related to human activities. However, natural processes can also lead to groundwater quality problems. High NH4, As and B concentrations have been identified in the confined, deep portion of the Niebla-Posadas aquifer, which is near the Cobre Las Cruces (CLC) mining complex. The mine has implemented a Drainage and Reinjection System comprising two rings of wells around the open pit mine, were the internal ring drains and the external ring is used for water reinjection into the aquifer. Differentiating geogenic and anthropogenic sources and processes is therefore crucial to ensuring good management of groundwater in this sensitive area where groundwater is extensively used for agriculture, industry, mining and human supply. No NH4, As and B are found in the recharge area, but their concentrations increase with depth, salinity and residence time of water in the aquifer. The increased salinity down-flow is interpreted as the result of natural mixing between infiltrated meteoric water and the remains of connate waters (up to 8%) trapped within the pores. Ammonium and boron are interpreted as the result of marine solid organic matter degradation by the sulfate dissolved in the recharge water. The light δ(15)NNH4 values confirm that its origin is linked to marine organic matter. High arsenic concentrations in groundwater are interpreted as being derived from reductive dissolution of As-bearing goethite by dissolved organic matter. The lack of correlation between dissolved Fe and As is explained by the massive precipitation of siderite, which is abundantly found in the mineralization. Therefore, the presence of high arsenic, ammonium and boron concentrations is attributed to natural processes. Ammonium, arsenic, boron and salinity define three zones of groundwater quality: the first zone is close to the recharge area and contains water of sufficient quality for human drinking; the second zone is downflow and contains groundwater suitable for continuous irrigation but not drinkable due to high ammonium concentrations; and the third zone contains groundwater of elevated salinity (up to 5940μScm(-1)) and is not useable due to high ammonium, arsenic and boron concentrations.

Abstract  Unicellular, planktonic, prokaryotic and eukaryotic photoautotrophs (phytoplankton) have an ancient evolutionary history on Earth during which time they have played key roles in the regulation of marine food webs, biogeochemical cycles, and Earth's climate. Since they represent the basis of aquatic ecosystems, the manner in which phytoplankton die critically determines the flow and fate of photosynthetically fixed organic matter (and associated elements), ultimately constraining nutrient flow. Programmed cell death (PCD) and associated pathway genes, which are triggered by a variety of abiotic (nutrient, light, osmotic) and biotic (virus infection, allelopathy) environmental stresses, have an integral grip on cell fate, and have shaped the ecological success and evolutionary trajectory of diverse phytoplankton lineages. A combination of physiological, biochemical, and genetic techniques in model algal systems has demonstrated a conserved molecular and mechanistic framework of stress surveillance, signaling, and death activation pathways, involving collective and coordinated participation of organelles, redox enzymes, metabolites, and caspase- like proteases. This mechanistic understanding has provided insight into the integration of sensing and transduction of stress signals into cellular responses, and the mechanistic interfaces between PCD, cell stress and virus infection pathways. It has also provided insight into the evolution of PCD in unicellular photoautotrophs, the impact of PCD on the fate of natural phytoplankton assemblages and its role in aquatic biogeochemical cycles.

Abstract  Urine patches within pasture soils are hotspots for nitrogen (N) cycling and losses, where nitrification inhibitors (NI) offer a means of reducing such losses. Within urine influenced soil, more research has been conducted for dicyandiamide (DCD) than 3,4-dimethylpyrazole phosphate (DMPP). Differences in the efficacy of these NI are often ascribed to a greater mobility of DCD, which may lead to spatial separation from NH4 (+) and nitrifying microorganisms. We tested the mobility of C-14-labelled DCD and DMPP relative to sheep urine-derived NH4 (+) in soil columns of contrasting texture and organic matter content, following simulated rainfall. We also assessed factors influencing the vertical mobility of these NI in soils, including solubility, sorption/desorption processes and microbial degradation and uptake. Following 40-mm rainfall, without the presence of sheep urine, the distribution of both NI were similar in the soil columns; however, there was a greater retention of DCD compared to DMPP in the top 1 cm. Both NI appeared to co-locate well with urine-derived NH4 (+), and the presence of sheep urine altered the leaching profile of the NI (compared to rainfall application alone), but this effect was inhibitor and soil-type dependent. A greater sorption to the soil matrix was observed for DCD in comparison to DMPP in all three studied soils, and the presence of urine generally increased desorption processes. Of the NI applied to the soil columns, 18-66 % was taken up within 30 min by the microbial community. However, only small amounts (< 1 %) were mineralized during this period. In conclusion, due to the greater adsorption of DCD as opposed to DMPP and similarity in the degree of co-location of both NI with urine NH4 (+), the results of this study suggest that differences in microbial uptake and degradation may be more important parameters for explaining differences in the efficacy of reducing nitrification. Further work is required to determine the comparative efficacy of both NI in reducing nitrification rates under field conditions in a range of soil types and environmental conditions.

Abstract  The effects of hypoxic conditions and elevated ammonia concentrations on the viability of embryos and newly hatched larvae of the red snapper (Lutjanus campechanus) were investigated. In all experiments, tested levels of hypoxia or ammonia concentrationswere applied to embryos and unfed newly hatched larvae from three different spawns. Exposures began at 1 h post fertilization (pf) and lasted until all individuals in a group had expired. Survival rates were monitored daily in duplicates for each spawn in each treatment. Fertilized eggs exposed to 2 mg L-1 dissolved oxygen (29% saturation) showed complete mortality before hatch while 81% of embryos in control groups (>85% saturation) hatched and subsequently maintained high survival until 5 days pf. Exposure to a moderate hypoxia (target 3 mg L-1, 43% saturation) reduced significantly the hatch rate and subsequent survival rates; the magnitude of the difference in survival rate between control and exposed groups increased from 10% at hatch to 45% at 5 days pf. When oxygen concentration was maintained high (83% saturation) until 36 h pf and then progressively reduced to reach 3 mg L-1 at 2 days pf, the survival of exposed embryos and larvae did not differ significantly from those recorded in control groups, although potential delayed or cumulative effects of the treatment after 4 days pf could not be evaluated in this experiment. Embryos exposed to 10 mg L-1 total ammonia (TA-N), which corresponded to unionized ammonia (UIA-N) concentrations ranging between 0.307 and 0.468 mg L-1 in the conditions of the experiment, exhibited significantly reduced hatch rates and complete mortality between 3 and 4 days pf; the latter period corresponds to the onset of exogenous feeding of red snapper. In contrast, control groups (TA-N < 0.26 mg L-1, UIA-N < 0.006 mg L-1) maintained high survival rates beyond 5 days pf indicating potential to successfully initiate exogenous feeding. Exposure to 1 mg L-1 TA-N (0.020 mg L-1 < UIA-N < 0.054 mg L-1) did not alter significantly survival with respect to control groups. Significant interactions between the spawn and the tolerance to hypoxia or elevated ammonia were detected in both experiments, indicating that variations among spawns need to be accounted for when determining safe levels for hatchery production.

Statement of relevance

Achieving a reliable supply of high quality eggs and larvae is one of the main challenges of the developing marine aquaculture industry.

Most studies to date have focused on maternal determinants of egg quality but the viability of embryos and newly hatched larvae can be impacted after fertilization if environmental conditions become unfavorable due to intensive hatchery conditions; this topic is poorly documented in marine fishes to date.

This study provides data on the effects of two major stressors acting under high density culture (hypoxia and elevated ammonia concentration) on embryos and newly hatched larvae of the red snapper; the results highlight the importance to consider variations among spawns/parents when determining safe levels for hatchery production and also the high sensitivity of red snapper to these stresses, suggesting that this topic should be investigated in other marine offshore species.

Relevance of the research to commercial aquaculture.

The research contributes to control egg quality. (C) 2016 Elsevier B.V. All rights reserved.

Abstract  Nitrification is an acidifying process that requires the addition of external alkalinity because of the alkaliphilic nature of the most ammonia-oxidizing bacteria. In this study, aerobic activated sludge was used as inoculum in an internal loop air-lift reactor, which resulted in successful enrichment of acid-tolerant nitrifying (ACIN) sludge at pH 6.0 by sequential addition of tea orchard soil suspension. The results showed that ACIN sludge had a remarkable acid tolerant capability with a volumetric ammonia conversion rate of 1.13 kg N m(-3) day(-1). ACIN sludge showed a higher maximum specific ammonia conversion rate (0.29 g N g(-1) VSS day(-1)) than neutrophilic nitrifying sludge (0.14 g N g(-1) VSS day(-1)) at pH 6.0 and had good resistance against pH fluctuations, with a maximum specific ammonia conversion rate (0.584 g N g(-1) VSS day(-1)) at pH 7.5. Microbial community analysis indicated that the higher abundance of acid tolerant Nitrosospira and ammonia-oxidizing archaea laid a solid foundation for the remarkable acid-tolerant capability of ACIN sludge.

Abstract  Nitrite is generated from the nitrogen cycle and its accumulation is harmful to environment and it can be reduced to nitric oxid by nitrite reductase. A novel gene from Bacillus firmus GY-49 is identified as a nirK gene encoding Cu-containing nitrite reductase by genome sequence. The full-length protein included a putative signal peptide of 26 amino acids and shown 72.73% similarity with other Cu-containing nitrite reductase whose function was verified. The 993-bp fragment encoding the mature peptide of NirK was cloned into pET-28a (+) vector and overexpressed as an active protein of 36.41 kDa in the E.coli system. The purified enzyme was green in the oxidized state and displayed double gentle peaks at 456 and 608 nm. The specific activity of purified enzyme was 98.4 U/mg toward sodium nitrite around pH 6.5 and 35 °C. The K m and K cat of NirK on sodium nitrite were 0.27 mM and 0.36 × 103 s-1, respectively. Finally, homology model analysis of NirK indicated that the enzyme was a homotrimer structure and well conserved in Cu-binding sites for enzymatic functions. This is a first report for nitrite reductase from Bacillus firmus, which augment the acquaintance of nitrite reductase.

Abstract  Degradation, impoundment, and channelization of streams is a global problem. Although stream restoration projects have increased in recent years, post-restoration, long-term monitoring is rare. In 2003, a channelized section of Wilson Creek (Nelson Co., Kentucky) was restored by creating a meandering channel, re-connecting the channel to its floodplain, and planting native riparian species: giant cane and bottomland forest species. Our main objective was to conduct a ten-year post-restoration assessment to determine long-term restoration outcomes of channel water quality, growth of trees planted in the riparian area, and soil development. Water quality, soil, and tree data collected in 2013-2015 was compared to 2004-2006 data. Quality of water parameters changed over time: sulfate, magnesium, calcium, potassium, alkalinity, pH, iron, and temperature decreased, whereas dissolved oxygen increased. Overall, soil pH, extractable ammonium, extractable nitrate, total carbon (TC), and total nitrogen (TN) increased over time. Effects were observed in restored riparian areas for pH, extractable ammonium, and TC; while TC and TN exhibited depth-dependent interactions. The carbon-nitrogen ratio in these soils significantly decreased over time for the reference sites, and the treatments recovered to near reference level. Platanus occidentalis (American sycamore) and Fraxinus pennsylvanica (green ash) individuals had higher survival (80% and 79%, respectively) than individuals of Quercus palustris (pin oak; 22%). Shelter and herbicide treatments had no effect on tree survival or height growth; however, height growth varied by species. Platanus occidentalis exhibited a greater than five-fold increase, F. pennsylvanica slightly increased, and Q. palustris decreased in height growth. Overall, water and soil quality improved over time at the restoration site, while tree survival and height growth exhibited species-specific outcomes.

Abstract  Delineating pollutant reactive transport pathways that connect local land use patterns to surface water is an important goal. This work illustrates high-resolution river mapping of salinity or specific conductance (SC) and nitrate (NO3-) as a potential part of achieving this goal. We observed longitudinal river SC and nitrate distributions using high-resolution synoptic in situ sensing along the lower Merced River (38 river km) in Central California (USA) from 2010 to 2012. We calibrated a distributed groundwater-surface water (GW-SW) discharge model for a conservative solute using 13 synoptic SC sampling events at flows ranging from 1.3 to 31.6 m(3) s(-1). Nitrogen loads ranged from 0.3 to 1.6 kg N d(-1) and were greater following an extended high flow period during a wet winter. Applying the distributed GW-SW discharge estimates to a simplistic reactive nitrate transport model, the model reproduced observed river nitrate distribution well (RRMSE=5-21%), with dimensionless watershed-averaged nitrate removal (kt) ranging from 0 to 0.43. Estimates were uncertain due to GW nitrate data variability, but the resulting range was consistent with prior removal estimates. At the segment scale, estimated GW-SW nitrate loading ranged from 0 to 17 g NO3- s(-1) km(-1). Local loading peaked near the middle of the study reach, a location that coincides with a shallow clay lens and with confined animal feed operations in close proximity to the river. Overall, the results demonstrate the potential for high-resolution synoptic monitoring to support GW-SW modeling efforts aimed at understanding and managing nonpoint source pollution.

Abstract  Tropical rainforest soils harbor a considerable diversity of soil fauna that contributes to emissions of N2O. Despite their ecological dominance, there is limited information available about the contribution of epigeal ant mounds to N2O emissions in these tropical soils. This study aimed to determine whether ant mounds contribute to local soil N emissions in the tropical humid rainforest. N2O emission was determined in vitro from individual live ants, ant-processed mound soils, and surrounding reference soils for two trophically distinct and abundant ant species: the leaf-cutting Atta mexicana and omnivorous Solenopsis geminata. The abundance of total bacteria, nitrifiers (AOA and AOB), and denitrifiers (nirK, nirS, and nosZ) was estimated in these soils using quantitative PCR, and their respective mineral N contents determined. There was negligible N2O emission detected from live ant individuals. However, the mound soils of both species emitted significantly greater (3-fold) amount of N2O than their respective surrounding reference soils. This emission increased significantly up to 6-fold in the presence of acetylene, indicating that, in addition to N2O, dinitrogen (N2) is also produced from these mound soils at an equivalent rate (N2O/N2 = 0.57). Functional gene abundance (nitrifiers and denitrifiers) and mineral N pools (ammonium and nitrate) were significantly greater in mound soils than in their respective reference soils. Furthermore, in the light of the measured parameters and their correlation trends, nitrification and denitrification appeared to represent the major N2O-producing microbial processes in ant mound soils. The ant mounds were estimated to contribute from 0.1 to 3.7% of the total N2O emissions of tropical rainforest soils.

Abstract  To investigate the effect of calcium and ABA on photosynthesis and the activities of antioxidant enzymes in cucumber seedlings under drought stress, the cucumber was used as the expe-riment materials, normal nutrient solution culture was considered as the control, and PEG-6000 application in the nutrient solution simulated the drought stress. There were five different treatments which were spraying water, ABA, CaCl2+ABA, LaCl3(calcium channel inhibitor)+ABA and EGTA (calcium ion chelating agent)+ABA under drought stress. The results showed that drought stress inhibited the growth of cucumber seedlings, and reduced the activities of antioxidant enzymes, nitrate reductase, net photosynthetic rate and fluorescence parameters of the cucumber seedlings leaves. The application of ABA reduced the inhibition of activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and ascorbate peroxidase (APX), photosynthesis (Pn, gs) and the fluorescence parameters (Fv'/Fm', qP and ETR), and decreased the damage of drought stress on plant. Spraying CaCl2+ABAsignificantly promoted the positive effect of ABA, while EGTA+ABA and LaCl3 +ABA didn't show the promoting effect.

Abstract  In Taihu Lake region, more and more paddy fields are being converted to vegetable fields, which cause serious soil acidification and decreased soil nitrogen retention. In this study, calcium carbonate and biochar were used as acidification amendments to test their ability on soil acidification remediation and soil nitrogen retention improvement. Calcium carbonate and biochar addition rates were determined by pH buffering curves. An incubation experiment with and without nitrogen fertilization and multi-leaching simulation tests were conducted. The soil nitrogen mineralization rate, dynamics of the nitrogen content in soils and leachates, and soil pH were measured. The results showed that 3.92×10-2 mol·kg-1 calcium carbonate and 27.73 g·kg-1 biochar should be added into the tested acidified vegetable soil to recover the original pH value. Without nitrogen fertilization, the addition of calcium carbonate increased the soil nitrogen mineralization rate by 37% but had no significant effect on mineral nitrogen content. However, biochar addition significantly improved the soil nitrogen mineralization rate by 35%-44% and nitrate content by 42%-58%. Nitrogen leaching loss was cut down by 42%-57% in biochar addition treatment because of the lower leachate volume and nitrogen concentration, while calcium carbonate addition increased nitrogen leaching loss by 12%-76% because of the higher leachate nitrogen concentration. After leaching, the soil pH decreased for all the treatments. The soil pH change was the lowest for calcium carbonate addition treatment under no nitrogen fertilization and the lowest for biochar addition treatment under nitrogen fertilization. This result suggests that calcium carbonate is more applicable for seriously acidified soils which are fallowed and biochar is more suitable for the intensified vegetable fields because it can improve the soil nitrogen retention and soil pH, and reduce the nitrogen leaching loss.

Abstract  Pterostilbene has been reported as a potential drug to inhibit oxidative stress and inflammation. However, the effect of pterostilbene on chondrocytes and osteoarthritis remains to be elucidated. We sought to investigate whether pterostilbene could protect chondrocytes from inflammation and ROS production through factor erythroid 2-related factor 2 (Nrf2) activation. The pterostilbene toxicity on chondrocytes collected from cartilages of Sprague-Dawley rats was assessed by CCK-8 test. Immunofluorescence and Western blotting explored the nuclear translocation of Nrf2. Nrf2 expression was silenced by siRNA to evaluate the involvement of Nrf2 in the effect of pterostilbene on chondrocytes. Finally, osteoarthritis model was established by the transection of anterior cruciate ligament and partial medial meniscectomy in rats, and then these rats received pterostilbene 30 mg/kg, daily, p.o. for 8 weeks. Histology and immunohistochemistry were used to assess histopathological change and Nrf2 expression in cartilage. Nuclear translocation of Nrf2 was stimulated by pterostilbene without cellular toxicity. Pterostilbene inhibited the level of COX-2, iNOS, PGE2, and NO, as well as the mitochondrial and total intracellular ROS production induced by IL-1β in chondrocytes, partially reversed by the Nrf2 silencing. Pterostilbene prevented cartilage degeneration and promoted the nuclear translocation of Nrf2 in cartilage. These results suggest that pterostilbene could inhibit the IL-1β-induced inflammation and ROS production in chondrocytes by stimulating the nuclear translocation of Nrf2.

Abstract  A field experiment was conducted to investigate the effect of controlled-release fertilizer (CRF) combined with urea (UR) on the soil fertility and environment in wheat-rice rotation system. Changes in four forms of nitrogen (total nitrogen, ammonium nitrogen, nitrate nitrogen, and microbial biomass nitrogen) and in activities of three soil enzymes participating in nitrogen transformation (urease, protease, and nitrate reductase) were measured in seven fertilization treatments (no fertilization, routine fertilization, 10%CRF+90%UR, 20%CRF+80%UR, 40%CRF+60%UR, 80%CRF+20%UR, and 100%CRF). The results showed that soil total nitrogen was stable in the whole growth period of wheat and rice. There was no significant difference among the treatments of over 20% CRF in soil total nitrogen content of wheat and rice. The soil inorganic nitrogen content was increased dramatically in treatments of 40% or above CRF during the mid-late growing stages of wheat and rice. With the advance of the growth period, conventional fertilization significantly decreased soil microbial biomass nitrogen, but the treatments of 40% and above CRF increased the soil microbial biomass nitrogen significantly. The soil enzyme activities were increased with over 40% of CRF in the mid-late growing stage of wheat and rice. By increasing the CRF ratio, the soil protease activity and nitrate reductase activity were improved gradually, and peaked in 100% CRF. The treatments of above 20% CRF could decrease the urease activity in tillering stage of rice and delay the peak of ammonium nitrogen, which would benefit nitrogen loss reduction. The treatments of 40% and above CRF were beneficial to improving soil nitrogen supply and enhancing soil urease and protease activities, which could promote the effectiveness of nitrogen during the later growth stages of wheat and rice. The 100% CRF treatment improved the nitrate reductase activity significantly during the later stage of wheat and rice. Compared with the treatments of 40%-80% CRF, 100% CRF reduced the soil nitrate content of 20-40 cm soil layer in wheat significantly suggesting it could reduce the loss of nitrogen.

Abstract  OBJECTIVES: The in-vitro dissolution of bioactive glass-based toothpastes and their capacity to form apatite-like phases in buffer solutions have been investigated.

MATERIALS AND METHODS: The commercial toothpaste samples were tested on immersion in artificial saliva, Earle's salt solution and Tris buffer for duration from 10min to four days. The powder samples collected at the end of the immersion were studied using solid-state 31P and 19F nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction and Fourier transform infrared (FTIR) spectroscopy. The fluoride concentration in the solution remained after the immersion was measured.

RESULTS: In artificial saliva and in presence of sodium monofluorophosphate (MFP), the bioactive glass and bioactive glass-based toothpastes formed fluoridated apatite-like phases in under 10min. A small amount of apatite-like phase was detected by 31P NMR in the toothpaste with MFP but no bioactive glass. The toothpaste with bioactive glass but no fluoride formed an apatite-like phase as rapidly as the paste containing bioactive glass and fluoride. By contrast, apatite-like phase formation was much slower in Earle's salt solution than artificial saliva and slower than Tris buffer.

CONCLUSIONS: The results of this lab-based study showed that the toothpaste with MFP and bioactive glass formed a fluoridated apatite in artificial saliva and in Tris buffer, as did the mixture of bioactive glass and MFP.

CLINICAL SIGNIFICANCE: The presence of fluoride in bioactive glass-containing toothpastes can potentially lead to the formation of a fluoridated apatite, which may result in improved clinical effectiveness and durability. However, this should be further tested intra-orally.

Abstract  Sulfur/dolomite and pyrite/dolomite autotrophic denitrification reactors were applied to treat the secondary effluent of wastewater treatment plant to explore the removal effect, the changes of microbial community, and recovery time of reactors after starvation period. It was shown in the results that after 30 d non-water starvation endurance, the effluent concentrations of NO3--N in sulfur/dolomite and pyrite/dolomite reactors increased from 1.78 mg·L-1, 11.32 mg·L-1 to 27.87 mg·L-1, 26.56 mg·L-1 respectively at the low temperature of 12-14℃. In addition, sulfur/dolomite and pyrite/dolomite reactors recovered within 5 d and 11 d since restarted and could maintain a good effect of nitrogen removal at low temperature. MiSeq high throughput sequencing results showed that the abundance and diversity of the bacterial communities in starvation period in both reactors were lower than those in recovery period. The dominating phylum was Proteobacteria in both reactors while the dominating class was β-Proteobacteria. Thiobacillus was identified as the main genus for denitrification in sulfur/dolomite reactor.

Abstract  This study evaluated the individual and interactive effect of phenol and thiocyanate (SCN-) on partial nitritation (PN) activity using batch test and response surface methodology. The IC50 of phenol and SCN- on PN sludge were 5.6 and 351 mg L-1, respectively. The PN sludge was insensitive to phenol and SCN- at levels lower than 1.77 and 43.3 mg L-1, respectively. A regression model equation was developed and validated to predict the relative specific respiration rate (RSRR) of PN sludge exposed to different phenol and SCN- concentrations. In the range of independent variables, the most severe inhibition was observed with a valley value (17%) for RSRR, when the phenol and SCN- concentrations were 4.08 and 198 mg L-1, respectively. An isobole plot was used to judge the combined toxicity of phenol and SCN-, and the joint inhibitory effect was variable depending on the composition and concentration of the toxic components. Furthermore, the toxic compounds showed independent effects, which is the most common type of combined toxicity.

Abstract  This study explored the effects of mulching straw mat, agricultural carpet, transparent-plastic film and horticultural fabric on nitrification-denitrification, nitrate reductase (NR), nitrite reductase (NiR), ammonium, nitrate and nitrite nitrogen in root-zone soil grown with three-year old apple trees (Malus domestica cv. Starkrimson) during summer and autumn. Results showed that the four treatments decreased nitrification intensity in summer soil, NiR activity in summer-autumn soil and the variation coefficient of nitrification-denitrification intensity and NR in both summer and autumn soil. The treatments increased the denitrification intensity, NR activity, ammonium nitrogen contents in summer-autumn soil and ammonium nitrogen contents in autumn soil. Straw mat treatment increased denitrification intensity and nitrate nitrogen contents in both summer and autumn soil and decreased the activity of NR and NiR in summer soil. The coefficient of variation of nitrification-denitrification intensity and NR activity treated by mulching straw mat was lower than those in the other treatments in both summer and autumn soil. Agricultural carpet increased the NR and NiR activity in summer soil, the nitrate nitrogen contents in summer-autumn soil and the denitrification intensity in autumn soil and decreased denitrification intensity in summer soil. Transparent-plastic film increased the nitrite nitrogen contents in summer soil, the contents of nitrate nitrogen in summer-autumn soil, the nitrification intensity and NiR activity in autumn soil, and decreased nitrate nitrogen contents in summer soil. Horticultural fabric increased denitrification intensity in summer soil, nitrification intensity in summer-autumn and autumn soil and the nitrate nitrogen contents in autumn soil. The four mulching treatments all promoted plant growth. In the four mulching treatments, the new shoot and trunk thickening growth were more under straw mat and horticultural fabric treatments. The four mulching treatments had different effects on nitrate metabolism in summer and autumn soil, but they were able to stabilize the soil nitrate metabolism and transformation. Among the treatments, straw mat had the best stable effect.

Abstract  AIMS: The preconditioning-like infarct-sparing and anti-inflammatory effects of the peptide hormone relaxin following ischemic injury have been studied in the heart. Whether reperfusion therapy with recombinant human relaxin-2, serelaxin, reduces myocardial infarct size and attenuates the subsequent NLRP3 inflammasome activation leading to further loss of functional myocardium following ischemia/reperfusion (I/R) injury is unknown.

METHODS AND RESULTS: After baseline echocardiography, adult male wild-type C57BL or eNOS knockout mice underwent myocardial infarction (MI) by coronary artery ligation for 30 min followed by 24 h reperfusion. Mice were treated with either serelaxin (10 µg/kg; sc) or saline 1 h prior to ischemia or 5 min before reperfusion. In both pre-treatment and reperfusion therapy arms, serelaxin improved survival at 24 h post MI in wild-type mice (79% and 82%) as compared with controls (46% and 50%, P = 0.01), whereas there was no difference in survival between serelaxin- and saline-treated eNOS knockout mice. Moreover, serelaxin significantly reduced infarct size (64% and 67% reduction, P < 0.05), measured with TTC staining, and preserved LV fractional shortening (FS) and end-systolic diameter (LVESD) in wild-type mice as compared with controls (P < 0.05). Interestingly, caspase-1 activity in the heart tissue, a measure of inflammasome formation, was markedly reduced in serelaxin-treated wild-type mice compared with controls at 24 h post-MI in both treatment modalities (P < 0.05). Genetic deletion of eNOS abolished the infarct-sparing and anti-inflammatory effects of serelaxin as well as functional preservation. Serelaxin plasma levels assessed at 5 min and 1 h after treatment, using ELISA, approximated physiologic relaxin levels during pregnancy in mice and parallels that in humans.

CONCLUSION: Serelaxin attenuates myocardial I/R injury and the subsequent caspase-1 activation via eNOS-dependent mechanism.

Abstract  Simultaneous measurements of precursor gases NH3,NO,NO2,SO2 and the main water-soluble ions in PM2.5 such as sulphate (SO42-),nitrate (NO3-) and ammonium (NH4+) (collectively called SNA)were carried out in the urban area of Beijing during 2015-01 to 2015-12,which obtained 325 groups of samples. PTFE membrane filters were used to collect particulate NH4+, NO3- and SO42-, followed by the online instruments to collect precursor gases. The pollution characteristics of the precursor gases and SNA were analyzed and their correlation was studied. The mean concentrations of NH3, NO, NO2, SO2, NH4+,NO3- and SO42- were 21.5, 17.7, 54.3, 14.2, 8.1, 13.5 and 12.7 μg·m-3 respectively during the period of monitoring, and SNA accounted for 43.4% of PM2.5. The concentrations of SO2,NOx and SNA declined compared to 2014. The concentrations of NO,NO2 and SO2 were highest in winter and lowest in summer. The concentration of NH3 was higher in summer and lower in autumn; The concentration and the percentage of NH4+ were stable during the four seasons,both the concentrations and the percentage of NO3- were lowest in summer. The concentrations of SO42- was highest in winter and the percentage was lowest in summer. The ratio of ([NO3-]+2[SO42-]) and NH4+ was 0.97 during the whole year, showing that anions mainly existed in the form of NO3- and SO42-. In summer, the ratio of[NO3-]+2[SO42-] and[NH4+] was slightly higher than 1.0, which was the reason why NO3- was bound to Ca2+, Mg2+ and Na+besides NH4+. With the increase of pollution, the mass concentration of precursor gases and SNA increased dramatically, among which NOx increased most rapidly, and SO2 decreased from severe pollution to serious pollution. The contribution rate of NH4+ was maintained at a relatively stable level. SO42- had a higher contribution when the pollution level was lower, whereas the concentration of NO3- was higher than others and contributed most to PM2.5 in heavy pollution. Heterogeneous transformation on the surface of particulate matter played a more important role in the formation of SO42- and NO3-. The correlations between NO3-, NO2 and NO,NH4+ and NH3,SO42- and SO2 were significant at the confidence level of 0.01. SO42- had negative correlation with SO2, and NO3- had positive correlation with NO2. Compared with NH3, the NH4+ concentration was more obviously affected by acid gases NO2, SO2.

Abstract  Zirconium modified diatomite was obtained by modifying raw diatomite with zirconium and the mass fraction of zirconia was 12.39% in the obtained material, which was proved to be amorphous via XRD. SEM images showed that porous floccules covered the surface of diatomite after modification and the specific surface area of the zirconium modified diatomite was 75.22 m2·g-1, larger than that of raw diatomite (14.00 m2·g-1). XPS spectra indicated that zirconia and diatomite were bonded together through chemical linkage, rather than physical deposition. The adsorption isotherm of phosphate by zirconium modified diatomite was fitted better to the Langmuir model with a calculated maximum adsorption capacity reaching 10.56 mg·g-1. The adsorption amount of zirconium oxide component in the material was estimated to be 81.67 mg·g-1 ZrO2, which was higher than that of pure zirconium oxides reported in previous studies. The adsorption amount of phosphate by zirconium modified diatomite decreased with the increase of pH. The adsorption was proved to be a ligand exchange process, supported by the XPS spectra of Zr3d region before and after adsorption. Chloride ion, sulfate ion and nitrate ion did not inhibit the adsorption of phosphate on the material, whereas coexistence of bicarbonate ions competed with phosphate ions to a certain extent. When treating eutrophic lake water with a phosphate concentration of 2 mg·L-1, the phosphate concentration level could meet the Ⅲ rank of Surface Water Environment Quality Standard of China by adopting the dosage of zirconium modified diatomite ≥1.25 g·L-1.

Abstract  Soil net nitrogen mineralization in cropland has a great influence on both agricultural non-point source pollution and soil nitrogen loss. A field plot experiment was conducted to explore the temporal variation of soil net nitrogen mineralization under plastic film mulching ridge-furrow in Wulongchi small watershed during summer maize growing period. Results showed that the soil net ammonification, nitrification, and nitrogen mineralization were significantly greater than those of non-mulched treatment, and the differences were 6.63, 12.96 and 19.59 mg·kg-1, respectively. During the summer maize growth period, the rate of soil net ammonification was high at seedling stage, low at heading stage, and high at maturation stage. Both the rates of soil net nitrification and nitrogen mineralization were high at jointing stage, low at heading stage, and high at maturation stage. The rate of soil net nitrogen mineralization under plastic film mulched had significant linear relation with the contents of soil total nitrogen, nitrate nitrogen, and soil water. In conclusion, the improved condition of soil water and temperature under plastic film mulched cultivation of summer maize in the growing period promoted soil net nitrogen mineralization.

Abstract  We examined the environmental factors that characterize the habitats of two submerged macrophytes, Myriophyllum spicatum and Hydrilla verticillata, in South Korea using generalized additive models (GAMs). We performed a vegetation survey and measured water depth and water velocity from May to September, 2014-2015. Averaged water quality data from the Ministry of Environment's national water quality measurement network from January 2012 to October 2015 were used for modeling. Potential habitats of M. spicatum were linked with chlorophyll a, nitrate nitrogen, suspended solids, water temperature, water depth, and water velocity (deviance explained = 28.7%, accuracy = 74%). In the case of H. verticillata, electrical conductivity and suspended solids were key habitat factors (deviance explained = 23.4%, accuracy = 75%). Model results were highly consistent with observations and field data. Model performances were evaluated by the accuracy rate, the area under the receiver operating characteristic curve, the kappa value, and field verification, and were in generally good agreement. Few studies have evaluated the developed models using the independent field data. By understanding the environmental factors that characterize the habitats for submerged macrophytes, our results contribute to the development of conservation and management strategies for river ecosystems.

Abstract  A modified cyclic activated sludge technology (CAST) treating domestic wastewater was employed to investigate the effects of different operating modes, such as C/P ratio, reflux ratio, and temperature on phosphorus removal. The results illustrated that at room temperature the phosphorus removal of the system improved significantly when the influent C/P ratio increased from 50 to 100, with the removal efficiency increasing rapidly from 15% to 95.6%. Decreasing the C/P ratio to 75, the phosphorus removal performance declined due to influent carbon source deficiency, and the mean phosphorous removal efficiency decreased to 51.4%. At the same time, the long-term addition of an easily degradable carbon source resulted in sludge bulking and a large amount of sludge loss. With a low C/P ratio, the phosphorus removal performance increased by 2.3 times when the sludge reflux ratio decreased from 25% to 12.5%. However, the phosphorus removal performance declined when reducing it to 0. The temperature experiment results showed that the phosphorous removal efficiency of the system remained stable, above 90%, in the low temperature system (14℃±1℃). However, the phosphorous removal efficiency of a shortcut nitrification system at high temperature (27℃±1℃) was only 14.1%, suggesting that a low temperature was beneficial for removing phosphorous. It was observed from the batch tests that the sludge at room temperature could utilize dissolved oxygen, nitrate, and nitrite as electron acceptors to take up phosphate. The sludge in the low temperature system could use both dissolved oxygen and nitrate as the electron acceptors. However, the sludge in the high temperature system could only use dissolved oxygen as the electron acceptors to take up phosphate. In addition, it was also found that sludge under starvation conditions resulting from short-term idling of the system favored phosphorus removal.

Abstract  OBJECTIVES: Redox regulation plays a crucial role in balancing the cardiovascular system. In this prospective study we aimed to identify currently unknown correlations valuable to cardiovascular research and patient management.

METHODS: Blood samples from 500 patients were collected directly before cardiosurgical interventions (Ethics Committee reference number 85/11). Four central redox parameters were determined together with about 30 clinical, anthropometric, and metabolic parameters.

RESULTS: Creatinine levels and pulmonary hypertension were significant predictors of the total antioxidant status (TAOS) in the patients; total glutathione levels were linked to C-peptide, and creatinine, gender, and ventricular arrhythmia influenced nitrate/nitrite levels. Notably, significant interactions were found between medication and redox parameters. Calcium channel blockers (CCBs) were positive predictors of total glutathione levels, whereas angiotensin-converting enzyme inhibitors and CCBs were negative predictors of NOx levels. Age showed the highest correlation with the duration of the intensive care stay, followed by NOx levels, creatinine, TAOS, and C-reactive protein.

DISCUSSION: In this prospective study we determined multiple correlations between redox markers and parameters linked to cardiovascular diseases. The data point towards so far unknown interdependencies, particularly between antihypertensive drugs and redox metabolism. A thorough follow-up to these data has the potential to improve patient management.

ABBREVIATIONS: A: absorption; ΔA: absorption difference; ABTS: 2,2'-azino-di(3-ethylbenzothiazoline sulfonate); ACE: angiotensin-converting enzyme; AO: antioxidant; ARB: angiotensin receptor blocker; BMI: body mass index; CAD: coronary artery disease; CCB: calcium channel blocker; CDC: coronary heart diseases; COPD: chronic obstructive pulmonary disease; CRP: C-reactive protein; CVD: cardiovascular diseases; Cu-OOH: cumene hydroperoxide; D: dilution factor; DAN: 2,3-diaminonaphtalene; DMSO: dimethylsulfoxide; DNA: deoxyribonucleic acid; DTNB: 5,5-dithiobis(2-nitrobenzoate); ε: extinction coefficient; EDRF: endothelium-derived relaxing factor; fc: final concentration; GPx: glutathione peroxidases; (h)GR: (human) glutathione reductase; GSH: (reduced) glutathione; GSSG: glutathione disulfide; GST: glutathione-S-transferase; Hb: hemoglobin; HDL: high-density lipoprotein; Hk: hematocrit; H2O2: hydrogen peroxide; ICS: intensive care stay; LDH: lactate dehydrogenase; LDL: low-density lipoprotein; MI: myocardial infarction; NED: N-(1-naphthyl)-ethylendiamine-dihydrochloride; NOS: nitric oxide synthase; NOx: nitrate/nitrite; NR: nitrate reductase; PBS: phosphate buffered saline; PCA: principle component analysis; PH: pulmonary hypertension; ROS: reactive oxygen species; RNS: reactive nitrogen species; RT: room temperature (25°C); SA: sulfanilamide; SOD: superoxide dismutase; SSA: sulfosalicylic acid; TAC: total antioxidant capacity; TAOS: total antioxidant status; TEAC: trolox equivalent antioxidative capacity; TG: triglycerides; tGSH: total glutathione; TNB-: 2-nitro-5-thiobenzoate; U: unit; UV: ultraviolet; VA: volume activity; Wc: working concentration; WHR: waist-hip ratio.