Concentrations Of TN Research Articles

Microecological health assessment of water environment and sediment based on metagenomics: a case study of Guixi River in Chongqing, China.

River sediment is vital in containing water pollution and strengthening water remediation. This paper has conducted a study on the microecological health assessment of the sediment and water body of Guixi River in Dianjiang, Chongqing, China, using metagenomics sequencing and microbial biological integrity index (M-IBI) technology. The analysis of physical and chemical characteristics shows that the concentration of TN varies from 2.62 to 9.76mg/L in each sampling section, and the eutrophication of the water body is relatively severe. The proportion of Cyanobacteria in the sampling section at the sink entrance is higher than that of other sites, where there are outbreaks of water blooms and potential hazards to human health. The dominant functions of each site include carbon metabolism, TCA cycle, and pyruvate metabolism. In addition, the main virulence factors and antibiotic resistance genes in sediment are Type IV pili (VF0082), LOS (CVF494), MymA operon (CVF649), and macrolide resistance genes macB, tetracyclic tetA (58), and novA. Correlation analysis of environmental factors and microorganisms was also performed, and it was discovered that Thiothrix and Acidovorax had obvious gene expression in the nitrogen metabolism pathway, and the Guixi River Basin had a self-purification capacity. Finally, based on the microecological composition of sediment and physical and chemical characteristics of the water body, the health assessment was carried out, indicating that the main pollution area was Dianjiang Middle School and the watershed near the sewage treatment plant. The findings should theoretically support an in-depth assessment of the water environment's microecological health.

How the land use/cover changes and environmental factors at different scales affect lake water quality in arid and semi-arid regions

The quantitative relationship between land use/cover change (LUCC) within basins, lake water environmental factors, and water quality has long been a popular research area. In this study, we investigated three typical basins (Ulansuhai Basin, Daihai Basin, and Dalinor Basin) in arid and semi-arid areas of China. The assessment was based on the China Land Cover Dataset (CLCD), which was used to calculate the land use dynamic degree index and Markov transfer matrix. Moreover, an econometric analysis model and a hybrid evolutionary algorithm (HEA) model were used to explore the quantitative relationship between LUCC and environmental factors on the lake water quality. The results showed that the LUCC of the three lake basins was dominated by cultivated land and grassland over the past 20 years. In all of the basins, grassland and water area were converted into cultivated land, water area decreased to varying degrees, and impervious surface area increased continuously. Moreover, the concentration of TN and TP were generally proportional to chemical oxygen demand concentration (COD), biochemical oxygen demand concentration (BOD5), and dissolved oxygen concentration (DO), but inversely proportional to water depth and transparency; the relationship between Nutrient concentration and pH was usually related to the ecological threshold. On the basin scale, the grassland and forestland played positive roles in improving water quality, while cultivated land and impervious surface were the main factors contributing to water pollution. Overall, this study provides a scientific theoretical basis for the rational utilization of land resources, improvement of lake water quality, and ecological protection of typical lake basins in arid and semi-arid regions.

Coupling membrane electro-bioreactor with anammox process to treat wastewater at low temperatures

Membrane bioreactors (MBRs)have been extensively applied to municipal wastewater treatment. Nevertheless, MBRs cannot eliminate nutrients to an adequate level without extra operation units and intensive chemical supplies. Furthermore, low temperatures destroy the performance of the MBR process. In this work, a pioneering anammox membrane electro-bioreactor (MEBR/anammox) system was designed and operated at a constant flow rate of 7L/d with continuous monitoring of sludge liquor temperature (8–22 °C). The MEBR/anammox worked with a sludge retention time (SRT) of 20 days and a hydraulic retention time (HRT) of 24 h. It was found that temperature variations did not significantly influence the effluents quality in terms of nutrients and COD. At lower operating temperatures, the effluent concentrations of NH4-N, TN, PO4-P, and COD in the MEBR-anammox were 0.77 mg/L, 6.42 mg/L, 0.80 mg/L, and 24.95 mg/L, respectively. The corresponding removal efficiencies were 94.46%, 88.62%, 95.60%, and 90.76%, respectively. Taken together, the implementation of a low/periodic direct current (DC) of 14.85 A/m2 and anammox process inside the MBR, achieving a MEBR/anammox, was found to enhance the efficacy of the treatment system, improve sludge properties and increase membrane fouling control in low-temperature milieus compared to traditional MBR. The MEBR/anammox system, introduced in this work, establishes an innovative wastewater technology that minimizes the footprint, capital and operating expenditures of the plant. In addition, this system could open new prospects for the treatment of municipal sewage in cold regions.

Mesocosm experimental study on sustainable riparian restoration using sediment-modified planting eco-concrete

The continued deterioration of riparian ecosystems is a worldwide concern, which can lead to soil erosion, plant degradation, biodiversity loss, and water quality decline. Here, taking into account waste resource utilization and eco-environmental friendliness, the sediment-modified planting eco-concrete with both H. verticillata and T. orientalis (SEC-H&T) was prepared and explored for the first time to achieve sustainable riparian restoration. Concrete mechanical characterizations showed that the compressive strength and porosity of SEC with 30% sediment content could reach up to 15.8 MPa and 21.25%, respectively. The mechanical properties and the sediment utilization levels of SEC were appropriately balanced, and potentially toxic element leaching results verified the environmental safety of eco-concrete modified with dredged sediments. Plant physiological parameters of both aquatic plants (biomass, chlorophyll, protein and starch) were observed to reach the normal levels in SEC during the 30-day culture period, and T. orientalis seemed better adapted to SEC environment than H. verticillate. Importantly, compared to SEC-H and SEC-T, SEC-H&T could effectively reduce the concentrations of COD, TN and TP by 58.59%, 74.00% and 79.98% in water, respectively. Notably, water purification mechanisms by SEC-H&T were further elucidated from the perspective of microbial community responses. Shannon index of bacterial diversity and proliferation of specific populations dominating nutrient transformation (such as Bacillus and Nitrospira) was increased under the synergy of SEC and aquatic plants. Correspondingly, functional genes involved in nitrogen and phosphorus transformation (such as nosZ and phoU) were also enriched. Our study can not only showcase an effective and flexible approach to recycle dredged sediments into eco-concrete with low environment impacts, but also provide a promising alternative for sustainable riparian restoration.

Short-term climate change influence on surface water quality impacts from agricultural activities.

Climate change is a global phenomenon that directly affects agriculture by altering crop yield, nutritional quality, pests, and plant diseases. The North Aegean Basin located in Turkey has considerable agricultural importance due to its fertile soils. Agricultural activities have increased significantly and uncontrollably in the last decade, resulting in dramatic changes in nitrate and phosphorus levels in surface water within the watershed. Changes in climatic conditions have the potential to impact the quantity and quality of water resources. Best management practices (BMPs) are presently utilized as a planning tool to enhance the quality of water resources. To develop policies in this regard, it is necessary to evaluate the effectiveness of BMPs. To this end, this study aims to investigate the potential effect of climate change on the surface water quality of the North Aegean Basin. For the period between 2010 and 2030, global climate data retrieved from Concentration Pathway (RCP) scenarios 4.5 and 8.5 and regionally downscaled were used to feed the Soil and Water Assessment Tool (SWAT) model. The various potential BMP scenarios were developed and simulated in the hydrological model by considering the effects of climate change. The RCP4.5 scenario reduced the precipitation by 15.11%, while the RCP8.5 scenario reduced the precipitation by 10.97%. Decreased precipitation also affected the runoff and the nutrient loads and concentrations. As a result of the RCP4.5 simulation, TP and TN concentrations increased by 24.42% and 58.45%, respectively, in the IST_KEN014 station. Improvements were observed in TN and TP concentrations with the effect of applied BMP simulations. Also, the results revealed that the applied BMP scenarios may contribute to considerable reductions in nutrient loads. Considering the RCP4.5 scenario, BMPs reduced TN loads in the basin by 2.42-10.97%, while reducing TP loads by around 3.60-16.81%. Considering the RCP8.5 scenario, the BMPs reduced the TN loads in the basin between 2.21 and 10.04%, while they reduced the TP loads between 3.57 and 16.67%.

Preliminary Population Exposure to Indoor Radon and Thoron in Dhaka City, Bangladesh

Radon, an element of natural radiation, is considered one of the leading causes of lung cancer worldwide. In Bangladesh, radon has been clarified as a foremost source of radiation exposure. Potential natural-radiation-induced elevated cancer risks were estimated in Bangladesh previously for the population. In this survey, as a very preliminary study in the country, comparative indoor radon (222Rn, Rn) and thoron (220Rn, Tn) concentration/population exposure was determined for the multistoried dwellings of south-western areas of Dhaka city. RADUET was used to assess annual Rn and Tn concentrations in determining the primary inhalation dose for the population. The annual effective dose of Rn and Tn was evaluated in this study for dwellings at 0.3 mSvy−1, constituting a Tn dose contribution of an average of 40% with a dwelling-based wide range of 10–96%. Thus, Tn should not be neglected for Bangladesh while estimating radiological inhalation dose from the indoor environment. Again, the equilibrium factors, F of Rn and Tn, were determined by short-term measurement at averages of 0.6 and 0.02, respectively. Furthermore, using questionnaire estimation by principal component analysis, PCA following the dwelling characteristics, human lifestyles, and estimated long-term indoor Rn and Tn concentrations, this paper discussed indoor atmospheric/Rn factors for the investigated multistoried dwellings in Dhaka city.

Advanced treatment of municipal reverse osmosis concentrate by a hybrid ozone-membrane aerated biofilm reactor system

Municipal reverse osmosis concentrate (mROC) possesses some characteristics, such as complex composition, poor biodegradability and high salinity. If mROC is discharged directly to the environment, it will cause serious damage to the ecological system. In this study, a hybrid ozone-membrane aerated biofilm reactor (O3-MABR) system was designed to treat mROC. This hybrid system combined the high efficiency of ozone to degrade refractory substances with the simultaneous removal of carbon and nitrogen in MABR. The effects of operating conditions including the ozone oxidation time, aeration pressure, hydraulic retention time (HRT) and the content of external carbon source on the system performance were investigated. Under the optimal parameters (ozone oxidation time was 10 s, aeration pressure and HRT of MABR-1 were 0.002 MPa and 28 h, respectively, and aeration pressure, HRT and carbon source addition amount of MABR-2 were 0.01 MPa, 22 h and 125 mg COD/L, respectively.), the average effluent COD and TN concentration of the coupling system were 41.4 mg/L and 12.3 mg/L, respectively, which met the Class A of the Discharge standard of pollutants for wastewater treatment plants (WWTP) (GB18918-2002). Furthermore, it revealed that the main phyla in biofilms of MABR were Proteobacteria and Firmicutes via high-throughput sequencing technology. This work had successfully developed an effective advanced treatment process of mROC, which lays a favorable foundation for subsequent technical promotion and applied research.

The interaction of tide and river flow on water quality in Hai Phong coastal waters (Lach Huyen - Do Son) drawn from field observation

This paper presents the results of a study on the impacts of the interaction of tide and river flow on water quality at the Hai Phong coastal water, outside the Nam Trieu estuary and Lach Huyen, drawn from field observation from October 14, 2022, to October 17, 2022. During the field observation, the dissolved oxygen concentration was measured, and water samples were taken at the surface, mid-depth, and bottom of 8 observational points at 1:00, 7:00, 13:00, and 19:00 h. Five sewage wastewater samples at Do Son coast and 6 coastal and river water samples were also taken. The collected seawater samples were laboratory analyzed to determine the concentration of BOD5, COD, TN, and TP. Additionally, the concentration of ions NH4+, NO2-, NO3-, and PO43- are determined by analyzing collected coastal, river, and sewage water samples and seawater samples at mid-depth at all observational points in a laboratory. It was found that the concentration of essential nutrients and other environmental components in wastewater samples generally does not exceed those specified in Vietnam regulations. The discharge of wastewater during the field observation was minimal. Thus it could be expected that the wastewater would not have a notable influence on seawater quality in the marine study area. Consequently, the study area’s primary source of nutrient pollutants was rivers. Time variation of the concentration of environmental components reveals that the nutrient concentration in the marine study area strongly influences by the interaction of the tide and river flow. The concentration of dissolved oxygen and major nutrient components in seawater at 8 points was within the limit of Vietnam standard for coastal water. However, significant nutrient concentration exceeds thresholds for eutrophication.

Current tomato production practices and their effects on plant and soil carbon and nitrogen dynamics

Assessment on how current standard tomato production impacts plant and soil C and N dynamics is necessary to improve sustainable nutrient management strategies for the intensive production of vegetables in warm climates. Carbon (C), nitrogen (N) and C:N ratios were determined for tomato variety ‘BHN 602’ (Solanum lycopersicum) in spring and fall season at harvest, in north Florida. A replicated field study was conducted where tomatoes were grown in sandy soils with fertilizers injected through the drip irrigation lines under a plastic-mulched bed system. Ammonium nitrate as the N source was applied at four different rates (0, 168, 224, and 280 kg ha−1). Soluble N fertilizer was applied weekly in 13 equal doses through the drip system for both seasons. Whole plant C:N ratios were similar among N rates in both spring and fall applications showing that the lowest applied N rate (168 kg ha−1) was sufficient in supplying N to the crop. Therefore, fertilized whole plant C:N ratios of 15.2 (spring) and 13.8 (fall) indicated optimal N uptake capability by the tomato crop. Soil TC and TN concentrations were maintained in the top 0-45 cm increments of the soil profile in both seasons, where concentrations did not differ among the rates of N fertilizer applied. Due to the lack of fertilizer input response, the reduction of N fertilizer rates would improve the sustainability of conventional vegetable production systems that are grown in sandy soil under a warm climate. Soil C was commensurate with soil N levels with regard to stabilizing the C:N ratio below 20, thus promoting mineralization in the soil for the subsequent crop.

Determining the main contributing factors to nutrient concentration in rivers in arid northwest China using partial least squares structural equation modeling

Understanding the main driving factors of oasis river nutrients in arid areas is important to identify the sources of water pollution and protect water resources. Twenty-seven sub-watersheds were selected in the lower oasis irrigated agricultural reaches of the Kaidu River watershed in arid Northwest China, divided into the site, riparian, and catchment buffer zones. Data on four sets of explanatory variables (topographic, soil, meteorological elements, and land use types) were collected. The relationships between explanatory variables and response variables (total phosphorus, TP and total nitrogen, TN) were analyzed by redundancy analysis (RDA). Partial least squares structural equation modeling (PLS-SEM) was used to quantify the relationship between explanatory as well as response variables and fit the path relationship among factors. The results showed that there were significant differences in the TP and TN concentrations at each sampling point. The catchment buffer exhibited the best explanatory power of the relationship between explanatory and response variables based on PLS-SEM. The effects of various land use types, meteorological elements (ME), soil, and topography in the catchment buffer were responsible for 54.3% of TP changes and for 68.5% of TN changes. Land use types, ME and soil were the main factors driving TP and TN changes, accounting for 95.56% and 94.84% of the total effects, respectively. The study provides a reference for river nutrients management in arid oases with irrigated agriculture and a scientific and targeted basis to mitigate water pollution and eutrophication of rivers in arid lands.

Assessment of Nutrient Removal in Surface Flow Constructed Wetland Treating Secondary Effluent with Low Organic, Nitrogen and Phosphorus Loads

Nutrient loads must be reduced to safe levels to protect sensitive receiving environments. This work presents the results of a 15-month monitoring program of a surface flow-constructed wetland (SFCW) in Queensland, Australia. The SFCW reduced the influent TN concentration by 54% and was able to retain 80% of the TN load, mainly due to the efficient removal of NOx and ammonium (92–100%). TP removal was negative due to the unaccounted loads from wildlife activity. During occasions of high loads, the wetland reduced TP concentrations by 77%. The hydraulic loading rate (HLR) correlated poorly to the TSS and TVS loads (r < 0.55); however, when adjusted to account for precipitation and evapotranspiration, stronger correlations (r > 0.78) were revealed. Strong correlations were revealed between adjusted HLR and TP (r = 0.87) and TN (r = 0.93). TN removal was highly governed by the inflow of TN concentration. TN removal could be predicted from the inflow concentration using the first-order plug-flow model (R2 = 0.72). The model suggests that the system has an irreducible threshold TN load of 0.115 kg-N per m2 per month. This work shows that SFCW can be effective in managing the nutrient loads even in systems that receive low organic and nutrient loads.

Response of Water Quality in Small Reservoirs to Landscape Composition, Landscape Configuration, and Reservoir Characteristics in the Upper Reaches of the Yangtze River During Dry Season

Small reservoirs in the Yangtze River are large in quantity and widely distributed, which have important ecological and economic benefits. It is of great significance to explore the response law of small reservoir water quality to environmental variables for improving reservoir water quality. Based on the measured water quality data of 36 small reservoirs in the upper reaches of the Yangtze River, combined with the measured water quality data, using correlation analysis, redundancy analysis, and other research methods, we divided the environmental variables into three categories:landscape configuration index, landscape composition index, and reservoir characteristic index, and explored their impact on the change in water quality index. The research results showed that:① farms were the main source of NO3--N, TN, and TP, and residential land was the main source of TP. Paddy, forest land, and wasteland had positive effects on the retention and purification of N and P in reservoirs. ② The LPI of farms was significantly positively correlated with the concentrations of TN and NO3--N in the reservoir, and the paddy and forest were significantly negatively correlated with the concentrations of NO3--N and TN in the reservoir. The PD of farms was positively correlated with TP. The LPI was negatively correlated with TP content. ③ The correlation between average reservoir depth and reservoir water quality was the strongest. Reservoir capacity, reservoir average depth, and reservoir LSI had significant positive effects on water quality improvement. ④ Among the environmental variables of the reservoir, landscape configuration index had the highest explanatory rate (24%), followed by that of the reservoir characteristics index (11%) and landscape composition index (9%). Watershed factors were the key factors (55%), and internal factors (19%) also had a significant influence on reservoir water quality. The research results can provide a theoretical basis for controlling water quality degradation of small reservoirs by managing and optimizing the landscape characteristics of reservoirs.

Evaluation and Prediction of Water Quality of Typical Wetlands in the Source Region of the Yangtze River

Wetlands play an important role in water storage and water conservation, but with global climate change, the degradation of wetland ecosystems is accelerating. In this study, we conducted research on the current situation and future prediction of water quality in typical wetlands in the source region of the Yangtze River to provide a scientific basis for the protection and restoration of wetlands in the source region of the Yangtze River. The Bayesian water quality assessment method and Yao Zhiqi evaluation method were used to evaluate the water quality of typical wetlands in the source region of the Yangtze River from 2016 to 2021 and based on the climate change scenarios of three RCPs (Representative Concentration Pathways) under the CMIP5 (Coupled Model Intercomparison Project Phase 5) global climate model and SWAT (soil and water assessment tool) hydrological model, the wetland water quality in the source region of the Yangtze River from 2022 to 2100 was predicted. The results show that the inter-annual changes in CODMn, NH3-N, and TN in a typical wetland show a downward trend, while the temperature and DO concentration show an upward trend from 2016–2021. The changes in CODMn, temperature, and conductivity within the year are abundant season > flat season > dry season; and DO, NH3-A, TN, and TP concentrations within the year are opposite. The water quality of typical wetlands in the source region of the Yangtze River has reached Class II and above. From 2022 to 2100, under climate change in the future, TN, TP, CODMn, NH3-N, and temperature in the wetland water in the source region of the Yangtze River will continue to rise, and the concentration of DO will continue to decline. Therefore, the pressure on water resources in the source region of the Yangtze River is further aggravated, so it is urgent to strengthen water resources protection.

Spatial and Longitudinal Distributions of Total Carbon, Nitrogen and Sulfur Together With Water‐Soluble Major Ions in Marine Aerosols Collected From the Western Pacific and Southern Ocean

AbstractTo explore the latitudinal distributions, sources and formation mechanisms of total carbon (TC), nitrogen (TN), sulfur (TS) and water‐soluble major ions (Na+, Cl−, SO42−, K+, nss‐SO42−, NH4+, NO3−, and MSA−), marine aerosol samples were collected over the Western Pacific (WP) and Southern Ocean (SO) from November 1994 to February 1995. Concentrations of TC ranged 30–390 ng m−3 (av. 190 ng m−3) over the SO, which are six times lower than those (1,200 ng m−3) over the WP, whereas concentrations of TN (av. 83 ng m−3) in the SO are three times lower than those (av. 232 ng m−3) over the WP. The highest concentrations of TC and TN were observed near New Zealand (7,000 and 720 ng m−3, respectively), suggesting a continental influence over the marine atmosphere. NO3−, tracer of anthropogenic sources, showed higher concentrations over the WP, whereas NH4+ concentrations over the SO are higher than the WP. The latter may be associated with penguin‐derived guano droppings from Antarctica. The concentration trends and statistical analysis demonstrate that the formation mechanisms of MSA− over the SO and WP is different. We found a strong correlation between MSA− and liquid water content (LWC) over the WP, suggesting the heterogenous aqueous phase production of MSA−, whereas aqueous phase reaction is less important over the SO. The strong correlation (R2 = 0.97) between nss‐Ca2+ and ss‐Ca2+ together with their similar relative abundances demonstrates an influence of CaCO3 eroded from coral reefs and shells and subsequent emission to the atmosphere by bubble bursting process.

Long-term operation of cathode-enhanced ecological floating bed coupled with microbial electrochemical system for urban surface water remediation: From lab-scale research to engineering application

Ecological floating bed coupled with microbial electrochemical system (ECOFB-MES) has great application potential in micro-polluted water remediation yet limited by low electron transfer efficiency on the microbial/electrode interface. Here, an innovative cathode-enhanced EOCFB-MES was constructed with nano-Fe3O4 modification and applied for in-situ remediation both at lab scale (6 L, 62-day operation) and demonstration scale (2300 m2, 1-year operation). The cathode-enhanced ECOFB-MES exhibited superior removal in TOC (81.43 ± 2.05%), TN (85.12% ± 1.46%) and TP (59.80 ± 2.27%), much better than those of original ECOFB-MES and anode-enhanced ECOFB-MES in the laboratory test. Meanwhile, cathode-enhanced ECOFB-MES boosted current output by 33% than that of original ECOFB-MES, which made a great contribution to the improvement of ectopic electronic compensation for pollutant decontamination. Notably, cathode-enhanced ECOFB-MES presented high efficiency, stability and durability in the demonstration test, and fulfilled the average concentration of COD (9.5 ± 2.81 mg/L), TN (1.00 ± 0.21 mg/L) and TP (0.10 ± 0.04 mg/L) of effluent water to meet the Grade III (GB 3838–2002) with stable operation stage. Based on the KOSIM calculation, the removal loads of cathode-enhanced ECOFB-MES in carbon, nitrogen and phosphorus could reach 37.14 g COD/(d·m2), 2.62 g TN/(d·m2) and 0.55 g TP/(d·m2), respectively. According to the analysis of microbial communities and functional genes, the cathode modified by Fe3O4 made a sensible enrichment in electroactive bacteria (EAB) and nitrogen-converting bacteria (NCB) as well as facilitated the functional genes expression in electron transfer and nitrogen metabolism, resulting in the synergistic removal of carbon in sediment and nitrite in water. This study provided a brandnew technique reference for in-situ remediation of surface water in practical application.

Effect of substrate on two anammox packing filler systems

The article investigated the effect of substrate ratio and shock load resistance on the nitrogen removal efficiency of curtain packing anammox filler and bundle packing anammox filler. The results had shown that the nitrogen removal performance was recommendable when the NH4 +-N: NO2 −-N was set as 1:1.20, regardless of the curtain packing filler or the bundle packing filler. After the total nitrogen concentration was directly increased from 770 mg/L to 1320 mg/L for 12 h. From the perspective of the steady of nitrogen removal performance, the bundle packing filler was better than curtain packing filler, and the effluent TN concentration was beyond 70 mg/L. Subsequently, within 1 day when the influent TN concentration increased to 770 mg/L, both filler systems quickly recovered. The structure of the bundle packing was beneficial to the fixed, cultured, and aggregation of anammox bacteria made it a better filler type. The high-throughput results showed that the dominant bacteria in the two packing fillers was Candidatus Kuenenia, which accounted for 15.16% and 22.85% in the curtain packing filler and the bundle packing filler system respectively.

An Innovative Waterwheel-Rotating Biological Contactor (WRBC) System for Rural Sewage Treatment

The treatment of rural sewage has become an important part of environmental protection. In this study, a novel waterwheel-rotating biological contactor (WRBC) system, with intensified biofilm and high-shock load resistance, was applied to treat rural sewage. When the COD concentration of actual sewage fluctuated between 79–530 mg/L, the COD removal efficiency was 41.3–94.5%, and the NH4+-N removal efficiency always reach 100% with actual sewage. The TN removal efficiency changed between 14.3–86.2%, which was greatly affected by the water intake. The effluent TN concentration ranged from 5 to 14 mg/L, which meets the emission requirements. It maintained an absolute effluent stability when the change rates of influent loads (N or COD) varied from −60% to 100%. The biofilm morphology and the composition of extracellular polymeric substances were evaluated based on SEM and FTIR spectra. The results showed that the -NH2 group content increased compared with the inoculated sludge, and the biofilm formed more uneven compact clusters after the treatment of actual sewage. Based on 16SrRNA high-throughput sequencing techniques, the bacterial diversity and microbial community structure of the WRBC system over time was revealed. This study may help guide optimization strategies for more effective pollutant removal in rural areas.

Spatiotemporal analysis and prediction of water quality in Pearl River, China, using multivariate statistical techniques and data-driven model.

Identifying spatiotemporal variation patterns and predicting future water quality are critical for rational and effective surface water management. In this study, an exploratory analysis and forecast workflow for water quality in Pearl River, Guangzhou, China, was established based on the 4-h interval dataset selected from 10 stations for water quality monitoring from 2019 to 2021. The multiple statistical techniques, such as cluster analysis (CA), principal component analysis (PCA), correlation analysis (CoA), and redundancy analysis (RDA), as well as data-driven model (i.e., gated recurrent unit (GRU)), were applied for assessing and predicting the water quality in the basin. The investigated sampling stations were classified into 3 categories based on differences in water quality, i.e., low, moderate, and high pollution regions. The average water quality indexes (WQI) values ranged from 38.43 to 92.63. Nitrogen was the most dominant pollutant, with high TN concentrations of 0.81-7.67mg/L. Surface runoff, atmospheric deposition, and anthropogenic activities were the major contributors affecting the spatiotemporal variations in water quality. The decline in river water quality during the wet season was mainly attributed to increased surface runoff and extensive human activities. Furthermore, the short-term prediction of river water quality was achieved using the GRU model. The result indicated that for both DLCK and DTJ stations, the WQI for the 5-day lead time were predicted with accuracies of 0.82; for the LXH station, the WQI for the 3-day lead time was forecasted with an accuracy of 0.83. The finding of this study will shed a light on an effective reference and systematic support for spatio-seasonal variation and prediction patterns of water quality.

Effect of Long Term Storage of Soil Sample on Some Chemical Properties of Vertisol and Andosol at Kulumsa Agricultural Sub Centers

The present study was conducted at the Kulumsa Soil and Plant Analysis Laboratory, Ethiopia from January 2021 to January 2022 to identify the appropriate storage duration of soil samples and recommend good storage materials for soil laboratories. The effects of soil sample storage on the pH, TN (%), OC (%), and available phosphorus were studied for 12 months. The highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus at the Kulumsa site were: 6.29 and 5.82; 0.17 and 0.12%; 2.93 and 1.70%; 22.53 and 10.88 respectively. At the Arsi Robe site, the highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus were 6.54 and 5.97, 0.16 and 0.12%, 3.02 and 1.00%, and 19.09 and 10.39 respectively. The highest and lowest concentrations of pH, TN (%), OC (%), and available phosphorus (mg kg1) at the Dera site were 9.14 and 8.47; 0.11, 0.07%; 4.36, 1.04%; and 111.85 and 75.37 respectively. Soil samples were stored in three storage containers with replications. The storage materials a card box with a plastic bag and a polyethylene bottle have not made any significant difference in the results of a soil sample stored under laboratory. A card box with a plastic bag was the appropriate material for soil sample storage for long-term analysis. However, based on the cost effectiveness and availability of the material to be purchased for the soil storage condition, the polyethylene plastic bag was the best option for soil sample storage under laboratory conditions.

The effects of organic fertilizer on loss risk of nitrogen and phosphorus in paddy ponded water.

There is a great challenge globally for both achieving high crop yields via fertilization and minimizing environmental pollution from nutrient losses. Organic fertilizer (OF) application has been extensively reported to effectively improve arable soil fertility and mitigate nutrient losses. However, few studies are available that accurately quantified the substitution rates of OF for chemical fertilizers (CF) that affect rice yield, the nitrogen/phosphorus in ponded water, and its loss potential in paddy field. Here, an experiment with 5 levels of CF nitrogen substituted by OF nitrogen was performed during the early stage of rice growth in paddy field of Southern China. The results showed that the first 6days and 3days following fertilization generally were risky period for N losses and for P losses, respectively, due to corresponding high concentrations in ponded water. Compared to CF treatment, over 30% of OF substitution rates significantly decreased the daily mean TN concentrations by 24.5-32.4%, while TP concentrations unaffected and rice yield maintained comparative levels. OF substitution also improved acidic paddy soils, with the increment of 0.33-0.90 unit for ponded water pH compared to CF treatment. Conclusively, the 30-40% of CF substituted by OF based on N amounts can be considered an ecological fertilization practice for rice production to mitigate environmental pollution due to lower N losses and without significant effect of grain yield. However, the attention also must be paid concerning the rise of environmental pollution risk from NH3 volatilization and P runoff after long-term OF application.