TP Concentrations Research Articles

Heatstroke risk informing system using wearable perspiration ratemeter on users undergoing physical exercise

We constructed an informing system to users for the heatstroke risk using a wearable perspiration ratemeter and the users’ thirst responses. The sweating ratemeter was constructed with a capacitive humidity sensor in the ventilated capsule. The timing point for informing heatstroke risk was decided to change from positive to negative on the second derivative of sweating curve. In addition, a wearable self-identification and -information system of thirst response was constructed with a smartphone. To evaluate the validity of wearable apparatus, we aimed to conduct human experiments of 16 healthy subjects with the step up and down physical exercises. The blood and urine samples of the subjects were collected before and after the 30-min physical exercise. The concentrations of TP, Alb, and RBC increased slightly with the exercise. In contrast, the concentrations of vasopressin in all subjects remarkably increased with the exercise. In almost subjects, they identified their thirst response until several min after the informing for heatstroke risk. In conclusion, the wearable ratemeter and self-information system of thirst response were suitable for informing system of heatstroke risk. The validity of timing point for informing heatstroke risk was confirmed with changes in the thirst response and concentrations of vasopressin in blood.

Influence of net cages on water quality and trophic status of Lake Victoria, Kenya: The case of Kadimu Bay

AbstractWater quality is a critical component regulating ecosystem functioning in aquatic habitats, requiring regular monitoring for sustainable ecosystem services. Cage fish farming has the potential to affect water quality because of its rapid increase in many African waterbodies in response to dwindling wild fish stocks. Thus, there is a need for more studies to guide sustainable cage aquaculture in African lakes and reservoirs. This study evaluated the possible effects of cage farming of Nile tilapia (Oreochromis niloticus) on water quality parameters and the trophic state of Kadimu Bay, Lake Victoria, Kenya. Sampling for physicochemical and biological variables, including nutrient load, was conducted from January to October 2021, at five fish cage sites and a control site within the bay. In situ measurements of physical variables were undertaken in the field, while analysis of water samples for nutrient loads, biological and chemical variables was undertaken in the laboratory, following the methods described in APHA (American public health association standard methods for the examination of water and waste water. APHA‐AWWA‐WEF, 2005). The Carlson's Trophic State Index (CTSI) was used to classify the trophic state of the cage sites, while the total nitrogen:total phosphorus (TN:TP) ratio was used to determine the primary productivity limiting nutrient in the bay. The study results indicated electrical conductivity was significantly lower at the control (97.53 ± 4.17 μS/cm), compared to cage sites (105.42 ± 5.32 μS/cm at the Utonga cage site to 112.84 ± 1.94 μS/cm at the Oele cage site), indicating water of relatively lower quality at the cage sites. Similarly, the nitrite concentrations were higher at cage sites (6.35 ± .96 μg/L at the Uwaria cage site to 3.16 ± 2.25 μg/L at the Utonga cage site), and lower at the control site (2.68 ± 1.39 μg/L). In all, 14 physicochemical variables did not vary significantly between the cage and control sites, with nine variables (temperature, turbidity, electrical conductivity, total suspended solids, particulate organic matter, chlorophyll‐a, TP, nitrate and TN) being within the recommended thresholds for aquatic life processes. The bay was evaluated as being in a light eutrophic state, indicating moderate influence of the fish cages on the trophic state of the sites. There was a moderate relationship between chlorophyll‐a and TP concentration at the sampling sites (R2 = .50), compared to a stronger relationship with (R2 = .78). The TN:TP ratios were <10 at the sampling sites, indicating nitrogen was the limiting factor for primary production in the bay. The calculated CTSI suggests that the bay exhibited a light eutrophic state. Overall, although the results of this study showed cage aquaculture is not a current challenge to the water quality of the bay, regular monitoring is nevertheless recommended to inform sustainable aquaculture development in the bay and lake.

Loss Characteristics of Non-point Pollutant from a Mixed Agriculture Watershed

In order to explore the temporal and spatial variability of non-point source pollution in an agriculture watershed, the water quality and quantity characteristics of five flood events at Shuangqiao station in Siheshui watershed (south China) were monitored. Five pollutants, including BOD5, TSS, TP, TN, and NH3-N, were measured and analyzed. The characteristics of pollutant concentrations and load-transport rates were investigated. It is shown that the pollutant concentrations in the flood events are remarkably larger than those in the non-flood events. The temporal sequences of peak values between pollutant parameters and runoff flows are explored. It indicates that the time interval would be short if the high-intensity rainfall occurred in the initial period of a flood event. Most of the peak values of pollutant concentrations preceded the flow peaks. The correlation coefficients between TSS and other pollutant concentrations are analyzed. It is shown that there is a significant correlation between the concentrations of TSS and TP in the flood events.

Influences of landscape pattern on water quality at multiple scales in an agricultural basin of western China

Determining the associations between landscape pattern and river water quality and quantifying the abrupt change points of landscape metrics are vital to optimize landscape planning and improve basin water quality. This study took an agricultural basin in western China as a case study. River water quality of 61 sub-basin outlets were monitored during wet and dry seasons from 2020 to 2021. Landscape metrics were extracted at 100 m, 300 m, 500 m riparian buffer and sub-basin scales, respectively. Relationships between water quality and landscape pattern at multiple scales were explored by using redundancy analysis (RDA). Results showed that urban-related landscape metrics served as the primary contributor to degrade water quality during both seasons, followed by cropland-related metrics, which might be attributed to the increase of urban land and reduction of agricultural chemical fertilizer use. Landscape metrics could better explain the water quality variations during wet season than dry season. The explanatory abilities of landscape metrics to overall water quality appeared little difference among spatial scales during wet season, whereas landscape metrics within 100 m riparian buffer had much larger explanatory rate than other spatial scales during dry season. Results of abrupt change point analysis revealed that the abrupt change interval values (ACIVs) of percentage of urban land (PLANDurban) and the largest patch index of urban land (LPIurban) differed among COD, TN, and TP. The recommended threshold values of PLANDurban and LPIurban for COD, TN, and TP management were smaller than 11.0%, 2.5%, and 1.0%, respectively. When the PLANDurban or LPIurban exceeded 19.0%, the TN, TP, and COD pollution would all significantly accelerate. Therefore, a limit value of 19% of PLANDurban and LPIurban, respectively is put forward. From dry season to wet season, the ACIVs of PLANDurban and LPIurban for COD concentration increased, whereas they decreased for TN and TP concentrations. Our results can provide scientific insights into sustainable landscape planning and effective water quality protection in agricultural basins.

Application of a three-dimensional ecological model to develop nutrient management plans for Lake of the Woods

This paper presents the development of a three-dimensional hydrodynamic-ecological model for Lake of the Woods (LoW) to assess the impact of nutrient inputs on the lake’s ecological processes. LoW is a large bi-national water body with complex geometry and topography and receives significant nutrients mainly from the Rainy River, with additional inputs from a few other smaller tributaries, and suffers from degraded water quality with seasonal cyanobacterial and harmful algal blooms. A high-resolution model developed here has a horizontal grid resolution of 250 m with a variable vertical grid resolution and can simulate hydrodynamics, in-lake nutrients dynamics, and phytoplankton biomass. Our model reproduced observed temporal and spatial distribution of nutrient and chlorophyll-a concentrations reasonably well. The calibrated model is used to explore simulating the spatial and temporal variability of ecological conditions of the lake and its response to nutrient load reductions. Based on a range of potential nutrient loadings, the model results suggest that different areas within LoW may respond differently to decreased phosphorus loadings. The model simulations predict that as nutrient loads into LoW decrease, water quality conditions will improve in most of the segments. In addition to naturally reducing internal load, external load reductions of 160 MTA from the baseline conditions (877 MTA) are necessary to reduce late summer average TP concentrations to 0.03 mg/L and total chlorophyll-a concentrations in the range of 7–12 μg/L.

Phosphorus concentrations in sediments from the equatorial Amazon estuary, Furo of Muriá, Pará State, Brazil

We characterized the spatial and seasonal distributions of different phosphorus fractions in surface sediments from the Furo of Muriá estuary by chemical fractionation. Five phosphorus species were successfully separated: phosphorus bound to Fe/Al oxyhydroxides (non-apatite inorganic phosphorus (NAIP) ranging from 164.54 to 280.32 μg g-1), phosphorus bound to calcium (apatite phosphorus (AP) ranging from 63.02 to 102.80 μg g-1), inorganic phosphorus (IP, ranging from 227.21 to 378.61 μg g-1), organic phosphorus (OP, ranging from 30.33 to 135.88 μg g-1) and total phosphorus (TP, ranging from 257.54 to 507.73 μg g-1), in which 88% of TP is constituted by IP. Statistical results showed that seasonality was not a major factor influencing phosphorus concentrations. Considering the classification of estuarine sediment conditions, we can conclude that the TP concentrations found in Furo of Muriá do not yet indicate the risk of environmental deterioration.

Optimization of operating parameters for biogas production using two-phase bench-scale anaerobic digestion of slaughterhouse wastewater: Focus on methanogenic step.

The objective of the present study was an optimization of operating parameters and the performance of the methanogenesis reactor in phased anaerobic digestion (AD) of slaughterhouse wastewater at 37.5°C. Accordingly, the feedstock of the methanogenic reactor was effluent from the hydrolytic-acidogenic reactor operating at HRT of 3-days and OLR of 1789 mg/L. The methanogenesis phase was also investigated at different hydraulic retention time (HRT) values ranging from 12 to 3days at 3-day intervals, and organic loading rates (OLR) of 149, 199, 298, and 596mg of COD/L. The methanogenesis reactor effluent concentrations of TN, TP, PO4-3, SO4-2, and S2-2 were ranging between 424-464, 83-117, 63-86, 130-197, and 0.98-1.02mg/L, respectively. The removal efficiencies of TN and TP were vary from 10-17% to 17-21%, respectively. The average biogas production was 125 ± 16, 150 ± 10, 185 ± 4, and 154 ± 17mL at HRT of 12, 9, 6, and 3days, respectively. Methane quality (%) and yield (mg/L of COD) were 55-67% and 0.02-0.03, respectively. Furthermore, the average stability indicator parameter values of (total volatile fatty acid (TVFA) = 520 ± 19mg/L, total alkalinity (TotA) = 1424 ± 10mg/L, TVFA:TotA. Ratio = 0.36, salinity = 1172mg/L, pH = 6.92) and performance indicator parameters removal efficiency (RE) for (chemical oxygen demand (COD) = 81%, volatile solid (VS) RE = 95%, biogas production = 185 ± 4mL, methane yield = 0.03 per mg COD consumed) were achieved at HRT of 6days and OLR of 298mg of COD/L. Low removal efficiencies of TP and TN at all HRT/OLR were observed for the methanogenic reactor signifying further treatment system.

Analysis of Pollution Characteristics and Sources in Surface Water in Typical Crop-Producing Areas of Qinghai Province

Currently used pesticides and organochlorine pesticides (OCPs), nitrogen and phosphorus were analyzed in surface water from 26 sampling sites of agricultural areas in Qinghai Province to elucidate their pollution characteristics and sources. The results showed that most of these currently used pesticides, with the exception of chlorpyrifos, were generally not detected. However, two OCPs were commonly detected in surface water from four typical crop-producing areas. The residual concentrations of hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) measured 0~1.68 ng/L and 0.41~2.41 ng/L, respectively, in the water from the four crop-producing areas. The residues of these two OCPs pesticides were much lower than the standard limit of surface water environmental quality. The main forms of HCHs and DDTs were β-HCH and pp'-DDE, respectively, indicating that the residues of HCHs and DDTs in the surface water of the four crop-producing areas in Qinghai were mainly derived from historical drugs that had degraded for a long time. The average concentrations of TN, NO3--N and NH4+-N in the surface water of 26 sampling sites of four typical crop areas in Qinghai Province were 2.95, 1.71 and 0.17 mg/L, respectively. According to the national surface water environmental quality standards, TN concentrations in 57.7% of these sampling sites exceeded the Class V water standards. The average concentration of NO3--N was more than 70 times that of NH4+-N. Nonetheless, there were no significant differences in the concentrations of TN, NO3--N and NH4+-N in the four crop-producing areas. The concentrations of NO3--N and NO3--N in the surface water were positively correlated with the TN concentration (p < 0.05), indicating that the sources of nitrogen in the surface water were relatively consistent. The average value of TP concentrations in the surface water from these sampling sites was 0.034 mg/L, with no significant differences among different producing areas. The N/P values in surface water from the four crop-producing areas of Qinghai Province had a range of 9.2~302. Phosphorus was the limiting factor for the proliferation of plankton in water. Reducing the input of phosphorus in these areas may be the key to preventing the deterioration of water quality. Significant negative and positive correlations exist between HCHs and nitrate nitrogen, and total phosphorus, respectively, which may be attributed to the proliferation of degrading microorganisms caused by the eutrophication of water. The research results will help to identify the characteristics and sources of surface water pollution in the crop-producing areas of Qinghai Province, and provide data support for Qinghai Province to build an export area for green organic agricultural and livestock products.

Influence of tannic acid concentration on the physicochemical characteristics of saliva of spider monkeys (Ateles geoffroyi).

Tannins are a chemical defense mechanism of plants consumed by herbivores. Variations in salivary physicochemical characteristics such as pH, total protein concentration (TP), and presence of proline-rich proteins (PRPs) in animals have been reported as a mechanism to protect the oral cavity when consuming food with variations in pH and tannins. Variations in salivary physiochemistry as adaptations for consuming tannin-rich foods have been found in omnivorous and folivorous primates, but have not yet been reported in frugivorous species such as spider monkeys. We therefore assessed changes in pH using test strips, TP concentration by measuring absorbance at 595 nm in a spectrophotometer and salivary PRPs using the SDS-PAGE electrophoresis technique in the saliva of nine captive spider monkeys in response to the consumption of solutions with different concentrations of tannic acid. The results showed variations in pH, TP concentration and the presence and variation of possible salivary PRPs associated with tannic acid concentration. These findings suggest that spider monkeys may tailor their salivary physicochemical characteristics in response to the ingestion of potentially toxic compounds.

Comparative study on phycoremediation performance of three native microalgae for primary-treated municipal wastewater

The current study was aimed to investigate the performance of three native microalgae in primary-treated municipal wastewater with regard to their nutrient removal, water quality improvement for reuse, and in vivo Chl-a -based biomass production. The microalgae species belonged to three different taxonomic classes, namely blue–green blue-green algae Nostoc muscorum , diatom Navicula veneta , and green microalgae Chlorella vulgaris . The comparative phytoremediation potentials of the microalgae species and the consortium were evaluated for 7 days-exponential growth phase employed in the batch systems. The results showed that the interaction between in vivo Chl-a concentration and residual concentration of TN, TP, and COD was notable. COD, TN, and TP treatment efficiencies were in the ranges of (85.7–95.7%), (72–96.9%), and (86.07–99.8%), respectively. The final concentrations of TN, TP, and COD in effluent provided by N. veneta treatment complied with EU Directive 91/271, EU Directive COM (2018)337, and national legislation, whereas the results of C. vulgaris partially complied with these legislations. Concerning the phycoremediation efficiency and the growth characteristic of the monoculture and mixed culture of the native microalgae, it was concluded that the monocultures in most cases were superior to the consortium culture. Diatom N. veneta had the highest growth rate (0.88 ± 0.04 day −1 ), Chl-a-biomass yield (50.45 ± 1.5 mg L −1 ), and removal efficiency (96.9 % TN, 99.8 % TP, 95.7 % COD). The results also reveal that the native species effectively reduce TN, TP, and COD concentrations of wastewater, and the diatom N. veneta may be a strong novel candidate for phytoremediation systems. • Three native microalgae were tested for their removal performances of pollutants in pre-treated municipal wastewater. • In vivo Chl-a fluorescence was significantly associated with the residual concentration of TN, TP, and COD. • Diatom Navicula veneta is a novel candidate in the sustainable bioremediation of municipal wastewater. • Phycoremediated municipal wastewater by diatom fulfilled the limit values of EU Directive 91/271 and EU COM(2018) 337.

Simulation on water quality of reservoir at construction phase by pollutant release from oxidation of waste rocks rich S and Fe

The presence of sulfur and iron in waste rocks produced during reservoir construction can generate acid rock drainage (ARD). Its environmental impact however, has often been neglected. Therefore, lab experiments were firstly conducted to simulate the release of main pollutants when the waste rocks having been submerged at the bottom of a reservoir in Guizhou Province, China. The impact of pollutants released on water quality during impounding was then predicted by a two-dimensional model MIKE21 coupled with ECO Lab module. Results showed that the argillaceous rock mainly produced acid and sulfate through oxidation. Based on release experiment, the model suggested that the average concentrations of TP, SO 4 2- , and Fe 3＋ peaked rapidly in the cross section about 100 m downstream of the waste rock yards when water level reached 855 m. At this point, the average Fe 3＋ concentration exceeded the standards of drinking water source and remained for 6 days, while the average TP concentration downstream exceeded the standards for 60 days. The water quality would meet the standards because of the dilution effect on pollutants when the water level was above 883 m. However, the release of phosphate from combined cycles of “P-Fe-S” should be paid more attention during impoundment. Based on the simulation results and existing actual cases, it showed that the anaerobic environment caused by impoundment can significantly reduce the negative impact from ARD. The study would provide a new insight for the stacking of engineering waste rocks and environmental risk assessment of the reservoir under construction. • Impact on water quality by waste rocks during reservoir construction was simulated. • SO 4 2- , TP and Fe 3+ mainly came from argillaceous rock through microbial oxidation. • P released from waste rocks through combined cycles of “P-Fe-S” should be concerned. • The pollutants migrated downstream to the front of the dam with water level rise. • Anaerobic environment due to impoundment reduced the impact of ARD from waste rocks.

Alleviating eutrophication by reducing the abundance of Cyanophyta due to dissolved inorganic carbon fertilization: Insights from Erhai Lake, China

The eutrophication of lakes is a global environmental problem. Regulating nitrogen (N) and phosphorus (P) on phytoplankton is considered to be the most important basis of lake eutrophication management. Therefore, the effects of dissolved inorganic carbon (DIC) on phytoplankton and its role in mitigating lake eutrophication have often been overlooked. In this study, the relationships between phytoplankton and DIC concentrations, carbon isotopic composition, nutrients (N and P), and hydrochemistry in the Erhai Lake (a karst lake) were investigated. The results showed that when the dissolved carbon dioxide (CO2(aq)) concentrations in the water were higher than 15 µmol/L, the productivity of phytoplankton was controlled by the concentrations of TP and TN, especially by that of TP. When the N and P were sufficient and the CO2(aq) concentrations were lower than 15 µmol/L, the phytoplankton productivity was controlled by the concentrations of TP and DIC, especially by that of DIC. Additionally, DIC significantly affected the composition of the phytoplankton community in the lake (p<0.05). When the CO2(aq) concentrations were higher than 15 µmol/L, the relative abundance of Bacillariophyta and Chlorophyta was much higher than those of harmful Cyanophyta. Thus, high concentrations of CO2(aq) can inhibit harmful Cyanophyta blooms. During lake eutrophication, when controlling N and P, an appropriate increase in CO2(aq) concentrations by land-use changes or pumping of industrial CO2 into water may reduce the proportion of harmful Cyanophyta and promote the growth of Chlorophyta and Bacillariophyta, which may provide effectively assist in mitigating water quality deterioration in surface waters.

Engineering demonstration of the remediation of urban water using a novel MES enhanced ecological floating bed: From construction to long-term performance

An innovative ecological floating bed coupled with sedimental microbial electrochemical system (ECOFB-MES) was designed for urban water remediation. A demonstration-scale ECOFB-MES of approximately 500 m2 was firstly constructed to perform the remediation of 8040 m2 urban water located in Nanning, Guangxi Zhuang Autonomous Region, China. During one-year operation, the COD, NH4+–N, NO3¯–N and TP concentrations stabilized around 10.3 ± 4.0 mg/L, 0.04 ± 0.02 mg/L, 0.61 ± 0.27 mg/L and 0.12 ± 0.05 mg/L from May 2021 to December 2021. The COD, TN and TP removal loads in April when MESs were connected were 72.47 g/d/m2, 4.26 g/d/m2 and 0.39 g/d/m2, which were 3.6, 15.3 and 2.8 times higher than those in January (open circuit). The average TC removal efficiency of sediment near anode was 36.7 %, which was 2.4 times higher than that of sediment far from anode (15.5 %). The average current of the MESs improved from 0.6 ± 0.1 mA to 32.0 ± 2.9 mA with reducing external resistance gradually, which was responsible for higher TC removal efficiency and lower dissolved oxygen (DO) concentration (7.78 ± 1.35 mg/L), which could enhance nitrogen removal. The MES enhanced the total number of species and the bacteria diversity of polyester fibers and roots in the same coupled system. The dominant functional bacteria such as Pseudomonas, Gemmobacter, Aeromonas and Arthrobacter beneficial for oxygen reduction and nitrogen removal were found on biocathode, and this indicated that biocathode of present system could reduce nitrate mainly through heterotrophic nitrification and aerobic denitrification. Results from the president research indicated that the ECOFB-MES provides a rewarding reference for practical application of polluted urban water remediation.

Comprehensive treatment of latex wastewater and resource utilization of concentrated liquid

Latex wastewater is a kind of refractory organic wastewater containing high concentrations of organics and ammonia nitrogen. In this work, the combined process of forward osmosis (FO) and reverse osmosis (RO) was designed to treat the latex wastewater in the whole process, achieving the water recovery rate of 99% and basically no waste discharge after the catalytic oxidation process. The turbidity of the latex wastewater was decreased to below 1 NTU by microfiltration pretreatment, and then using MgCl2 worked as the draw solution for FO process to treat the latex wastewater. Different operation conditions including adding acid or scale inhibitor as the pretreatment methods were conducted to improve the treatment performance of the combined process. After the treatment of the whole process, the concentration of COD was less than 20 mg⋅L−1, the concentration of NH3-N was less than 10 mg⋅L−1, and the concentration of TP was less than 0.5 mg⋅L−1 for the treated latex wastewater. The water quality met standards of industrial water reuse after the complete analysis of the treated latex wastewater, meanwhile, useful substances of L-Quebrachitol (L-Q) were successfully extracted from the concentrated solution. Therefore, the combined process of FO and RO could realize the efficient treatment and reuse of latex wastewater, which provided with some important guidance on the industrial application.

A Study on Identifying Priority Management Areas and Implementing Best Management Practice for Effective Management of Nonpoint Source Pollution in a Rural Watershed, Korea

It is difficult to accurately identify and manage the paths of nonpoint source (NPS) pollution in rural watersheds because their discharge patterns vary depending on season, region, and agricultural characteristics. In this study, flow and water quality during rainfall events were monitored in Songya watershed, an impaired, rural area in South Korea. A method of identifying priority management areas was proposed through scientific objectification and quantification of key factors controlling NPS, such as land use, agricultural type, and load. For the load calculation, a watershed model was developed using Hydrological Simulation Program Fortran (HSPF). Three priority management areas—Mulhan Stream, Osan Stream, and the upstream area of Songya Stream—were selected. Using the developed model, constructed wetlands with the capacity of 1000 m3 were applied at the lower reach of each priority management subbasin and the impacts on NPS pollution reduction were tested. The simulated results showed that BOD and TP concentrations at the outlet of Songya watershed were lowered by 9.2% and 6.0%, respectively. It is expected that the method proposed in this study for identifying priority management areas and implementing best management practice in agricultural watersheds can be applied to similar areas which struggled with NPS pollution.

Transformation trend of nitrogen and phosphorus in the sediment of the sewage pipeline and their distribution along the pipeline

Microorganisms transform nitrogen and phosphorus in the sediment of sewage pipelines. When the sediment was scoured by water flow, these elements migrate. This work studied the changes in biofilm morphology and microbial community structure, and focused on the differences in the transformation of nitrogen and phosphorus along the pipeline. The results showed that the nitrogen and phosphorus concentrations varied systematically with time and space (the front, middle, and posterior segments of the pipe). With time, amino acid nitrogen (AAN) concentration in the sediment gradually decreased, NH4+-N concentration slowly increased, NO3−-N concentration began to increase after 25 days, and TP concentration continued to increase after 9 days. The AAN, NH4+-N, and TP concentrations were highest in the posterior segment of the pipe and lowest in the front segment. However, NO3−-N showed two stages: its concentration was highest in the front segment and lowest in the posterior segment during the first 17 days, after which the opposite was observed. Changes in the nitrogen and phosphorus concentrations were related to the microbial communities in the sediments. The abundances of Rhodobacter (0.001 <p ≤ 0.01), Trichococcus (p ≤ 0.001), Nakamurella (0.01 <p ≤ 0.05), and norank_f__norank_o__PeM15 (0.001 <p ≤ 0.01) in the terminal sediments were significantly higher than those in the initial sediments. Meanwhile, the abundances of Clostridium_sensu_stricto_1, Rhodobacter, norank_f__norank_o__PeM15, and Brevundimonas were different in the front, middle, and posterior segments. Furthermore, nitrogen and phosphorus were easily adsorbed on the small particles and were scoured and re-deposited on the posterior segment of the pipe, resulting in enrichment. The temporal variation in nitrogen and phosphorus and its spatial distribution along the pipeline were due to the combination of biotransformation and migration.

A Simulation Experiment on Quality Dynamics of Reclaimed Water under Different Flow Exchanges.

Reclaimed water plays an important role in maintaining urban aquatic ecosystems, especially in areas with water shortages. However, there is little information on water quality dynamics and its driving mechanism in reclaimed water bodies. The simulated experiments were conducted to investigate the effect of flow exchange on water quality dynamics and soil microbial diversity for 100% reclaimed water and mixed water (50% reclaimed and 50% stream water), and the exchange periods ranged from 2 to 40 days. The results showed that the degradation coefficients (K) of CODMn and NH3–N were 0.015 d−1 and 0.001 d−1 for the mixed water, while their K values were negative for the reclaimed water. The flow exchange had little effect on water quality dynamics for the mixed water, which may be attributed to the relatively low concentration of TP in this reclaimed water. A small or great exchange period led to a relatively high fluctuation in K during the experimental period and corresponded to a worse soil microbial diversity. These results indicate that it is not recommended to fill an isolated urban lake with 100% reclaimed water and that a suitable flow exchange period of 5~10 days could help self-purify the water quality.

Dynamics of serum immunoglobulin G and total protein concentrations in dairy calves during the first 2 weeks of life

The aim of the present study was to describe the dynamics of serum IgG (determined with radial immunodiffusion) and total protein (TP; determined with refractometry) concentrations during the first 16 d of life. Secondary objectives were to evaluate the transfer of passive immunity (TPI) classification at d 1 of life as a conditional factor for the aforementioned dynamics, and to describe over time changes on calves' TPI classification. At a commercial raising operation, 36 calves (19 Holstein, 17 Jersey) were sampled immediately after arrival (d 1) and at d 4, 8, 12 and 16 of life, for serum IgG and TP concentration, and hematocrit determination (HCT). Transfer of passive immunity was categorized based on serum IgG (IgG-Poor: IgG <18 g/L; IgG-Good: IgG 18 to <25 g/L; IgG-Excellent: IgG ≥25 g/L) and TP concentrations (TP-Poor: <5.8 g/dL; TP-Good: 5.8 to <6.2 g/dL; TP-Excellent: ≥6.2 g/dL). Multiple linear regression was used to evaluate serum IgG and TP changes over time, considering the effects of time after birth, breed, HCT, and TPI classification at d 1 of life. At d 1, median serum IgG and TP concentrations were 29.9 g/L and 6.3 g/dL, respectively (interquartile ranges: 21.3–42.3 g/L and 5.6–6.7 g/dL, respectively). Dynamics of serum IgG and TP concentrations were conditional to TPI at d 1 of life. Serum IgG concentration declined over time for IgG-Excellent and IgG-Good calves (18.1 and 4.6 g/L, respectively), but remained constant for IgG-Poor calves. Serum TP concentration declined over time in the 3 TPI groups but it was more marked for TP-Excellent (27%) and TP-Good (19%) than for TP-Poor (14%) calves. At d 1, 83.3% of the calves were classified as IgG-Excellent or IgG-Good, whereas 77.8, 55.6, 41.7, and 58.3% of calves were classified within these categories at d 4, 8, 12, and 16 of life, respectively. Similarly, at d 1, 66.7% of calves were classified as TP-Excellent or TP-Good, whereas 47.2, 36.1, 25.0, and 2.8% were classified within these categories at d 4, 8, 12, and 16 of life, respectively. In summary, our results indicate that serum IgG and TP concentrations decline over 16 d of life, and the decline is associated with TPI classification at d 1 of life. Further studies are needed to determine the biological implications of serum IgG and TP decline after d 1 of life, and to elucidate the factors determining the different dynamics. Our results suggest that current thresholds for TPI classification should be interpreted carefully when the age of calves is unknown or outside the age range used to define those thresholds (>24 h to 7 d).

Decline in submerged macrophyte beds in the Pearl River Delta, China, 2015–2020

To maintain submerged macrophyte beds (SMBs), a sound understanding of the factors that influence their succession is required. The aim of this study was to determine what influenced the succession of SMBs in a tidal river system, namely the Pearl River Delta, China (PRD). Surveys were carried out from 2015 to 2020 and a range of environmental (16) and ecological parameters were measured that could support an examination of the distribution and variation in SMBs. The coverage area, species richness, and biomass were measured at the community level, while nine morphological traits of the dominant species, Vallisneria denseserrulata, were measured at the population level. The results showed that, in 2015, the SMB community was distributed in sporadic patches and the community was dominated by multiple species. In 2018, V. denseserrulata grew continuously from February to August in all sections but its growth through the overwintering period (December) followed two patterns: recession (Pattern 1) or continuous growth (Pattern 2). Principal component analysis highlighted that the clonal growth ability, sexual propagation allocation, and perennial growth were related to different patterns of V. denseserrulata growth in the overwintering period. Pattern 1 was characterized by a low clonal growth ability and no sexual propagation, while Pattern 2 was characterized by a strong clonal growth ability and sexual propagation over winter. In 2019, the community was dominated by a single species of V. denseserrulata and macrophytes had disappeared from most river sections. The results from redundancy analysis implied that the decline in the SMBs from 2015 to 2020 was probably related to increases in the (1) TP concentrations in the sediment, (2) occupation of SMB habitats, and (3) annual river runoff in pre-flooding periods.

The effects of thermosonication on quality parameters of cashew apple nectar: An optimization study for processing conditions

Thermosonication is an alternative treatment to process juices avoiding the thermal degradations promoted by conventional heat treatments. Therefore, the aim was to determine the optimal parameters of thermosonication to treat cloudy cashew nectar to inactivate polyphenol oxidase-(PPO), while promoting the maintenance of some bioactive compounds. The effects of ultrasound energy density-(UED) and temperature on PPO inactivation and some quality properties such as total phenolic-(TP), ascorbic acid-(AA) and color difference-(ΔE*) were determined and revealed by mathematical models. The increase in only one parameter (temperature or UED) caused a rise in PPO inactivation, while the other quality properties were constant. The same concentration of TP was obtained (426 mg/L) with high UED - low temperature (25 °C–595 J/g) or low UED – high temperature (121 J/g–57 °C). The highest levels of PPO inactivation, TP and AA content (1171 mg/L) were provided when treatment of approximately 350 J/g UED was performed at a high temperature (65 °C). An increase in temperature affected ΔE* more than UED, the highest color change was observed at 598 J/g and 45 °C. Thus, the optimal parameters of thermosonication were determined as 300 J/g and 60 °C.