Complete long-term monitoring of greenhouse gas emissions from a full-scale industrial wastewater treatment plant with different cover configurations.

The greenhouse gas (GHG) emissions from wastewater treatment plants (WWTPs), consisting mainly of methane (CH4) and nitrous oxide (N2O), have been constantly increasing and become a non-negligible contributor towards carbon neutrality. The precise evaluation of plant-specific GHG emissions, however, remains challenging. The current assessment approach is based on the product of influent load and emission factor (EF), of which the latter is quite often a single value with huge uncertainty. In particular, the latest default Tier 1 value of N2O EF, 0.016 ± 0.012 kgN2O-N kgTN-1, is estimated based on the measurement of 30 municipal WWTPs only, without involving any industrial wastewater. Therefore, to resolve the pattern of GHG emissions from industrial WWTPs, this work conducted a 14-month monitoring campaign covering all the process units at a full-scale industrial WWTP in Shanghai, China. The total CH4 and N2O emissions from the whole plant were, on average, 447.7 ± 224.5 kgCO2-eq d-1 and 1605.3 ± 2491.0 kgCO2-eq d-1, respectively, exhibiting a 5.2- or 3.9-times more significant deviation than the influent loads of chemical oxygen demand (COD) or total nitrogen (TN). The resulting EFs, 0.00072 kgCH4 kgCOD-1 and 0.00211 kgN2O-N kgTN-1, were just 0.36% of the IPCC recommended value for CH4, and 13.2% for N2O. Besides, the parallel anoxic-oxic (A/O) lines of this industrial WWTP were covered in two configurations, allowing the comparison of GHG emissions from different odor control setup. Unit-specific analysis showed that the replacement of enclosed A/open O with enclosed A/O reduced the CH4 EF by three times, from 0.00159 to 0.00051 kgCH4 kgCOD-1, and dramatically decreased the N2O EF by an order of magnitude, from 0.00376 to 0.00032 kgN2O-N kgTN-1, which was among the lowest of all full-scale WWTPs.

Enhanced methane production from source-separated human feces (brown water) by single phase anaerobic co-digestion: Effects of different co-substrates.

Based on the concept of source separation of brown water (BW, human feces with flushing water) and yellow water (urine) in rural area, anaerobic co-digestion of BW with agricultural waste is a promising and effective method for rural waste treatment and resource recovery. The purpose of this study was to investigate the performance of different agricultural wastes (peanut straw (PST), peanut shell (PSH), swine wastewater acting as co-substrate for anaerobic co-digestion with BW, and the relative mechanisms were explored. When the mixed ratio was uniformly set as 1:1 (mass ratio, measured by volatile solid (VS)) and initial VS load as 20 g/L, the maximum cumulative methane production obtained by co-digestion (21 days) of BW and PST was 688 mL/g-VS, which performed better than the individual substrates (341 mL/g-VS), as well as the average of the sole BW and sole PST groups (531.2 mL/g-VS). The most impactful advantage was ascribed to the promotion of hydrolytic and acidogenic enzyme activities. The addition of PST also reduced the production of endogenous humus, which is difficult for biodegradation. Microbial community analysis showed that different co-substrates would affect the microbial community composition in the reactor. The relative abundance of hydrolytic acidogens in the PST and PSH co-digestion groups were higher than that in the SW co-digestion and sole BW groups, and the methanogenic archaea were dominated by the acetate-trophic Methanotrichaceae. The overall results suggest that anaerobic co-digestion is a feasible method, and co-digestion of BW and PST can improve methane production potential.

Reduction of greenhouse gas emissions from closed activated sludge- to aerobic granular sludge-based biosystems via gas circulation.

Greenhouse gas (GHG) emissions from biological treatment units are challenging wastewater treatment plants (WWTPs) due to their wide applications and global warming. This study aimed to reduce GHG emissions (especially N2O) using a gas circulation strategy in a closed sequencing-batch reactor when the biological unit varies from activated sludge (AS) to aerobic granular sludge (AGS). Results show that gas circulation lowers pH to 6.3 ± 0.2, facilitating regular granules but elevating total N2O production. From AS to AGS, N2O emission factor increased (0.07-0.86 %) due to decreasing ammonia-oxidizing rates while the emissions of CO2 (0.3 ± 0.1 kg-CO2/kg-chemical oxygen demand) and CH4 remained in the closed biosystem. The gas circulation decreased N2O emission factor by 63 ± 15 % after granulation higher than 44 ± 34 % before granulation, which is implemented by heterotrophic denitrification. This study provides a feasible strategy to enhance heterotrophic N2O elimination in the biological WWTPs.

Quantitative distribution and quantized ecological threat of microplastics in farmland: Shanghai as an example.

The occurrence of microplastics (MPs) in farmlands poses a threat to soil health and crop yield. There needs to be more research on the role of cropping patterns in the accumulation of MPs and quantizing the threat of MPs on soil health and crop yield. In this study, a field study was carried out to explore the role of cropping patterns in the accumulation of MPs in agricultural soil in Shanghai, China. Furthermore, the specific effect and importance of MPs and each soil physicochemical indicator to soil health and crop yield were clarified, and the threat of MPs in reducing soil health and crop yield was quantized. Relative lower MPs abundance was detected in Shanghai. MPs abundance in vegetable fields was significantly higher than that in orchards. The broad source of MPs, the acceleration of plastics breaking under artificial disturbance and warmer temperatures, and the block of MPs exchange could account for the quicker accumulation of MPs in vegetable fields. MPs have a negligible effect on microbial diversity and metabolic activity which plays a role in soil enzyme activity. Besides, MPs served as one of the critical factors for rice yield reduction.

Exploring into a light-avoided environment: Mechanical-thermal coupled conditions responsible for the aging behavior of plastic waste in landfills.

Plastics in landfills undergo a unique micronization process due to multi-factor and light-avoided conditions, but their aging process in such a typical environment remains unexplored. This study investigated the aging behavior of polyethylene plastics, representative of landfills, under simulated dynamic mechanical forces and high temperature-two prevalent environmental factors in landfills. The study explored the individual and combined contributions of these factors to the aging process. Results indicated that high temperature played a primary role in aging plastics by depolymerization and degradation through ·OH production, while mechanical forces contributed mainly to surface structure breakdown. The combined effect leads to more serious surface damage, creating holes, cracks, and scratches that provide access for free radical reactions to plastic bulk, thereby accelerating the aging and micronization process. The resulting microplastics were found to be 14.25 ± 0.53 µg L-1. Aged plastics exhibit a rapid aging rate of depolymerization and oxidation compared to virgin plastics due to their weak properties, suggesting a higher potential risk of microplastic generation. This study fills a knowledge gap regarding the aging behavior of plastics under complex and light-avoided landfill conditions, emphasizing the need for increased attention to the evolution process of microplastics from aged plastic waste in landfills.

Occurrence of veterinary antibiotics in animal manure, compost, and agricultural soil, originating from different feedlots in suburbs of Shanghai, East China.

The present study aims to monitor and assess the occurrence of veterinary antibiotics (VAs) in animal manure, compost, and fertilized soil, originating from different large-scale feedlots. The corresponding concentrations of 39 types of VAs in 8 large-scale feedlots of pig, dairy cow, and poultry were sampled in different seasons and analyzed using LC-MS. The results indicated that 17 types, 16 types, and 5 types of VAs were detected in the swine manure, compost, and fertilized soil with the concentrations of 0.003-17.82, 0.002-9.59, and 0.004-0.007 mg kg-1 (dry matter), respectively; 3 types, 2 types, and 1 type of VAs were detected in the dairy manure, compost, and fertilized soil with the concentrations of 0.003-1.94, 0.014-0.044, and 0.025 mg kg-1 (dry matter), respectively; 7 types, 5 types, and 1 type of VAs were detected in the poultry manure, compost, and fertilized soil with the concentrations of 0.035-1.06, 0.018-0.049, and 0.019 mg kg-1 (dry matter), respectively. The main antibiotic classes persisted in the animal manure and their composting product and fertilized soil were sulfonamides (SAs), macrolides (MAs), and tetracyclines (TCs). Thus, this study would help to adopt strategies in pollution control of VAs and environmental protection of agriculture.

[Spatiotemporal Distribution of Ammonia Emissions from Poultry Farming in the Yangtze River Delta Based on Online Monitoring Derived Local Emission Factors].

In order to obtain the ammonia emission level and space-time distribution characteristics of the poultry production industry in the Yangtze River Delta, an online high-resolution monitoring system was used to continuously monitor the atmospheric ammonia concentration in the breeding house and compost shed in a typical large-scale layer farm. By obtaining the ammonia emission level and emission factor during each growth stage, we established the localized ammonia emission inventory for the poultry production industry in the Yangtze River Delta. The results showed that the average daily ρ(NH3) in the breeding house and compost shed for spring, summer, autumn, and winter were (1.85±0.38), (4.58±0.33), (3.87±0.12), and (2.83±0.47) mg·m-3 and (2.04±0.50), (4.04±1.04), (2.51±0.67), and (1.55±0.16) mg·m-3 respectively. Ammonia emissions showed a significant daily hourly change trend. The highest hourly ammonia concentration in the layer house appeared from 13:00-14:00 in the afternoon, and the minimum appeared from 01:00-03:00 in the morning. The highest hourly ammonia concentration in the compost shed occurred between 16:00-19:00 in summer and autumn, whereas the diurnal changes in spring and winter were not significant. Hourly changes in ammonia emissions during the day were mainly affected by daily temperature, poultry activities, and manure management. Ammonia concentrations at different growth stages of laying hens showed significant differences. ρ (NH3) from young chickens, laying hens, and pre-eliminated chickens were (1.85±0.38), (2.83±0.47), and (1.61±0.32) mg·m-3, respectively. The ammonia emission rate from laying hens reached 1.53 times and 1.65 times that of young chickens and pre-eliminated chickens, respectively. Metabolism levels and feed intake at different growth stages were the main reasons for the differences in ammonia emissions. Ammonia emission factors for the layer house and compost shed in spring, summer, autumn, and winter were (0.13±0.02), (0.54±0.01), (0.39±0.01), and (0.17±0.01) g·(bird·d)-1 and (0.07±0.01), (0.17±0.02), (0.08±0.01), and (0.04±0.01) g·(bird·d)-1, respectively. Annual ammonia emission factors reached (0.11±0.06) kg·(bird·a)-1 and (0.03±0.02) kg·(bird·a)-1, respectively. Our results suggest that ambient temperature, ventilation mode, chicken house type, and manure removal frequency were the main influencing factors of ammonia emissions from poultry production. The uncertainty ranges of the ammonia emission coefficients reached±122%,±79%, and±74%, and±56%, respectively. Great uncertainties were generated when empirical emission factors were used for emission inventory establishment. Based on the results of online monitoring, model simulation, and literature analysis, we established an ammonia emission inventory for the poultry production industry within the Yangtze River Delta region by adopting the emission factors of (0.16±0.08) kg·(bird·a)-1. In 2019, the total ammonia emission from poultry production was (108.81±54.41) kt. In terms of spatial distribution, ammonia emission intensities in the northern regions were significantly higher than those in the southern parts. The ammonia emission intensities during summer were 3.38-3.56 times higher than those in spring and winter.

[Emission Characteristics, Transformation Mechanism, and Reduction Potential of Ammonia Emissions from a Crop Rotation System in Yangtze River Delta].

To study the characteristics and reduction potential of the ammonia emissions of a crop rotation system in the Yangtze River Delta, we monitored and compared the ammonia fluxes from two rotation systems:a conventional rice/winter wheat rotation system and a rice-shrimp cultivation/Chinese milk vetch rotation system. This study was conducted through closing chamber methods to investigate the influencing factors and transformation mechanism of ammonium emissions between the two studied cultivation patterns. Additionally, we established the temporal-spatial emission inventory by sorting out the local ammonia emission factors of farmland in the Yangtze River Delta in the last ten years. The emission reduction effects under different ammonia emission reduction paths were also obtained. The results showed that, the cumulative amount of ammonia emissions throughout the whole monitoring year for the conventional rice/winter wheat rotation system (CR-W) and the rice-shrimp cultivation/Chinese milk vetch rotation system (RS-C) were 65.95 and 20.31 kg·hm-2, respectively, whereas the ammonia loss rates of CR-W and RS-C were 10.86% and 9.20%, respectively. Field surface water NH4+-N, field surface water pH, and topsoil NH4+-N were the major internal factors of ammonia emissions from paddy fields, whereas topsoil NH4+-N and atmospheric temperature had an important impact on ammonia emissions in the wheat season. The ammonia flux/field NH4+-N ratio (ARN) of field surface water under the CR and RS modes in the rice season reached 0.35±0.27 and 0.14±0.19, respectively, which was 10-25 times that of topsoil in the wheat season, such that the ammonia emission flux in the rice season was significantly higher than that in the wheat season. Under the conditions of high field water pH (8.0-9.0), atmospheric temperature (>28℃), and wind speed (>5.0 m·s-1), the ammonia flux/field NH4+-N ratios (ARN) were around 1.6-4.6 times that under low pH, temperature, and wind speed conditions, indicating that those three factors were the main factors affecting the conversion of NH4+-N from farmland to atmospheric NH3. Fertilization types also had significant effects on ARN; under different conditions, the ARN of urea was 1.5-5.5 times that of organic fertilizer. In 2019, the ammonia emission flux of rice and wheat under a conventional planting pattern in the Yangtze River Delta were (49.2±17.6) kg·hm-2 and (16.0±13.5) kg·hm-2, respectively, whereas the ammonia loss rates of rice and wheat were (20.1±5.7)% and (5.9±3.6)%, respectively. The ammonia emission loss rate of the former was about three times that of the latter. The ammonia emission inventory built by local factors shows that the total ammonia emissions of the farmland rotation system in the Yangtze River Delta reached (400.3±206.4) kt in 2019, which was mainly concentrated in the central and northern regions of Anhui province and Jiangsu province, and the ammonia emission intensity reached (1.33±1.39) t·km-2. The selection of different emission factors had a relatively large impact on the change range of the inventory results, reaching the standard of -51.6%~51.6%. Through combing and analyzing the six main paths of ammonia emission reduction in farmland, it was found that nitrogen fertilizer synergism was the best way to reduce ammonia emissions, with the efficiency of (30.9±51.4)%; however, the grain yield increase rate was (-4.2±17.4)%, with great uncertainty. The ammonia emission reduction effect of adding soil additives was relatively poor (-5.4±45.1)%; however, the grain yield increase rate was the highest among those of the six emission reduction paths, reaching (6.8±23.9)%. The ammonia emission reduction effect and grain yield increase rate of the ecological planting and breeding mode were (22.3±15.1)% and (5.6±3.8)%, respectively, which had the advantages of reducing ammonia emissions and increasing crop yield.

Bright-Dark and Multi Solitons Solutions of (3 + 1)-Dimensional Cubic-Quintic Complex Ginzburg-Landau Dynamical Equation with Applications and Stability.

In this paper, bright-dark, multi solitons, and other solutions of a (3 + 1)-dimensional cubic-quintic complex Ginzburg-Landau (CQCGL) dynamical equation are constructed via employing three proposed mathematical techniques. The propagation of ultrashort optical solitons in optical fiber is modeled by this equation. The complex Ginzburg-Landau equation with broken phase symmetry has strict positive space-time entropy for an open set of parameter values. The exact wave results in the forms of dark-bright solitons, breather-type solitons, multi solitons interaction, kink and anti-kink waves, solitary waves, periodic and trigonometric function solutions are achieved. These exact solutions have key applications in engineering and applied physics. The wave solutions that are constructed from existing techniques and novel structures of solitons can be obtained by giving the special values to parameters involved in these methods. The stability of this model is examined by employing the modulation instability analysis which confirms that the model is stable. The movements of some results are depicted graphically, which are constructive to researchers for understanding the complex phenomena of this model.

[Spatial and Temporal Variation of Phytoplankton Community Structure and Its Influencing Factors in Shanghai River Channels].

In order to explore the spatial and temporal characteristics of the phytoplankton community structure and its influencing factors in Shanghai rivers, the water quality and phytoplankton community structure at 44 river channel sites in a central urban area, new town area, and rural area in Shanghai were investigated from September to October 2018 (autumn) and July to August 2019 (summer). The results showed that:① Chlorophyta was the dominant phyla during the autumn and summer, and was followed by Cyanobacteria and Bacillariophyta. Cyanobacteria dominated the phytoplankton community in terms of density. The number of species and density of phytoplankton were 24% and 2.77 times higher, respectively, than those during the summer and autumn. The dominance of Microcystis sp. was obvious during the autumn (Y=0.16), but there was no absolute dominant species during the summer. ② The difference in the number of phytoplankton species among the three regions was not significant, and the density of the total phytoplankton and cyanobacteria species showed a similar spatial pattern:rural area > new town area > central urban area. Additionally, no significant difference was observed in the total phytoplankton and Cyanobacteria density among the three regions during the autumn (P>0.05), whereas it was 1.82 and 1.93 times higher, respectively, in the rural area in comparison to the central urban area during the summer (P<0.05). Montecarlo test results revealed that the main factors affecting the phytoplankton community structure during the autumn were secchi disk transparency (SD), total phosphorus (TP), total nitrogen (TN), and turbidimetry (Turb), whereas these were TN, Turb, SD, and pH during the summer. ③ The results of a redundancy analysis (RDA) indicated that during the autumn, the phytoplankton in the rivers of the new town area were mainly affected by Turb, TN, and TP, while the rural rivers were mainly affected by SD. During the summer, the phytoplankton in the rivers of the new town and rural areas were mainly affected by TN and Turb. The influencing factors in the central urban area were complex.

Analyzing the adsorptive behavior of Amoxicillin on four Zr-MOFs nanoparticles: Functional groups dependence of adsorption performance and mechanisms.

In this study, four functional Zr-MOFs (UiO-66-H, -NH2, -NO2, -Cl) were prepared, characterized (FESEM, XRD, BET, XPS, FT-IR) and compared to remove low-concentration Amoxicillin (AMX) from water. Then UiO-66-NH2 was selected for further experiments due to its highest adsorption capacity (2.3 ± 0.4 mg g-1). The adsorption process followed pseudo-second order, Langmuir and Freundlich models. With pH increasing, deprotonation of functional groups in UiO-66-NH2 and AMX made adsorption interactions variable. The obvious spectra shift of FT-IR/XPS indicated that Lewis acid-base interaction was the main adsorption impetus; meanwhile hydrogen bonding interaction and π-π/n-π (electron-donator-acceptor) EDA interaction should be included. For Lewis acid-base interaction, the strength was controlled by percentage of amine group in UiO-66-NH2, mainly interacting with phenolic hydroxyl group in AMX. Due to changes in charge distribution of functional groups, there existed six kinds of π-π/n-π EDA interactions and thirteen types of hydrogen/π-hydrogen bonding interactions. Additionally, electrostatic interaction and molecular attraction also contributed to the AMX adsorption. Conclusively, analysis of functional groups interactions could help to comprehend adsorption mechanisms more profoundly and exploit functional adsorbents more efficiently.

Application of dairy manure as fertilizer in dry land in East China: field monitoring and model estimation of heavy metal accumulation in surface soil.

Manure-based fertilizer is usually applied to agricultural soils to increase soil fertility and improve soil quality. However, this practice has an impact on the soil environment, e.g., increasing heavy metal contents. The aim of this study was to evaluate and estimate the accumulation tendencies of eight heavy metals, including arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), lead (Pb), manganese (Mn), and zinc (Zn) in a soil fertilized continuously with dairy manure through a 5 years' field-scale experiment. Contents of the As, Cd, Cr, Cu, Mn, and Zn gradually increased with the fertilization time of dairy manure at the stable rate of around 326 t hm-2 year-1, leading to annual mean increases of 3.6%, 2.4%, 3.9%, 3.8%, 4.2%, and 6.1%, respectively. Based on the prediction of a dynamic mass balance model using the current practice, the contents of Cd and Zn in the fertilized soil would reach the Chinese standard values for agricultural soils in 48 and 35 years. The mitigation measures, such as lower application rates, for the environmental risk of heavy metal accumulation should be considered.

[Accumulation of Cd in Different Crops and Screening of Low-Cd Accumulation Cultivars].

Pot-culture experiments were carried out in Shanghai to screen crop varieties with low bioaccumulation properties with respect to cadmium (Cd). Eight common crops, such as green pepper, cucumber, cowpea, spinach, cauliflower, tomatoes, rice, and wheat, were planted in contaminated soil with different Cd concentrations of 0.23, 0.6, 1.2, 1.8, 2.4, and 3.0 mg·kg-1 to investigate the effects on biomass, Cd accumulation characteristics, and edible risk safety. The results indicated that:① With the increase in soil Cd content, the aboveground biomass of crops increased firstly and then decreased. The different crop types had different tolerance to Cd, with green pepper showed the strongest tolerance and spinach and tomato showed the least tolerance. ② The bioaccumulation factor of Cd in the edible parts of eight crops ranged in order of wheat > spinach > rice > green pepper > cauliflower > tomato > cucumber > cowpea. ③ Total Cd content in soil was significantly correlated with Cd content in the crops (P<0.05), and the order of the correlation coefficients was spinach > wheat > tomato > cucumber > green pepper > rice > cauliflower > cowpea. ④ The risk threshold value of Cd in soil based on the edible safety of different crops ranged in order of cowpea > cucumber > cauliflower > green pepper > tomato > rice > spinach > wheat. Cucumber, cowpea, and cauliflower were selected as the low-Cd-accumulating varieties according to their tolerance to soil Cd, bioaccumulation capacity, and edible risk threshold values.

Spatially Confined Tuning the Interfacial Synergistic Catalysis in Mesochannels toward Selective Catalytic Reduction.

Low-temperature selective catalytic reduction of nitrogen oxides (NO x) with NH3 (NH3-SCR) has been identified as a promising strategy to mitigate the pollution of NO x. The fine control of synergistic effect and the suppression of aggregation of the active component, however, are still the challenge because of the weak interaction between the active component and matrix. In this work, a series of Ce-promoted Mn-based heterogeneous catalysts supported on mesoporous silica (SBA-15) with different Mn contents were prepared by two separated impregnation processes. Low-temperature NH3-SCR activity demonstrates that the Mn content in the catalyst has a great influence on the activity of the NH3-SCR reaction. The 20% MnO x-CeO x/SBA-15 catalyst exhibited the best catalytic performance in a broad temperature window. Moreover, it exhibits enhanced resistance to SO2 and H2O and long-term durability during 72 h reaction. The highly dispersive active phase, the formation of solid solution, the high ratio of Ce3+, and the spatial confinement effect largely contribute to the outstanding activity and durability of the 20% MnO x-CeO x/SBA-15 catalyst. Finally, a monolithic catalyst fabricated by the 20% MnO x-CeO x/SBA-15 catalyst powder and cordierite substrate show promising industrial application.

Mesoporous WO3 Nanofibers With Crystalline Framework for High-Performance Acetone Sensing.

Semiconducting metal oxides with abundant active sites are regarded as promising candidates for environmental monitoring and breath analysis because of their excellent gas sensing performance and stability. Herein, mesoporous WO3 nanofibers with a crystalline framework and uniform pore size is successfully synthesized in an aqueous phase using an electrospinning method, with ammonium metatungstate as the tungsten sources, and SiO2 nanoparticles and polyvinylpyrrolidone as the sacrificial templates. The obtained mesoporous WO3 nanofibers exhibit a controllable pore size of 26.3-42.2 nm, specific surface area of 24.1-34.4 m2g-1, and a pore volume of 0.15-0.24 cm3g-1. This unique hierarchical structure, with uniform mesopores and interconnected channels, could facilitate the diffusion and transportation of gas molecules in the framework. Gas sensors, based on mesoporous WO3 nanofibers, exhibit an excellent performance in acetone sensing with a low limit of detection (<1 ppm), short response-recovery time (24 s/27 s), a linear relationship in a broad range, and good selectivity.

Heavy metals accumulation in soil after 4 years of continuous land application of swine manure: A field-scale monitoring and modeling estimation.

Land application of animal manure has been encouraged widely in China. This presents a risk of heavy metals (HMs) accumulation in the soil due to their high contents in the feeds and additives. A 4-year field-scale study was conducted to monitor and estimate HMs accumulation in the soil with land application of swine manure. The results show a clear tendency for As, Hg, Cr, Cu, Zn and Mn to increase gradually with the application duration, yielding an average annual increase of 0.57, 0.011, 6.20, 5.64, 22.58, and 23.45 mg kg-1, respectively, at the annual application rate of about 250 t ha-1 of swine manure. The estimation from the mass balance modeling indicates the environmental risk of Cd, Cu and Zn will exceed the threshold levels for agricultural soils in China in the next 10-50 years. Determination of a suitable application rate of animal manure would be the first consideration for mitigating the environmental risk of HMs currently.

[Response Characteristics of Algal Chlorophyll-a to Nitrogen, Phosphorus and Water Temperature in Lake Erhai Based on Quantile Regression].

Based on water quality monitoring data of Lake Erhai from 1990 to 2013,the yearly and seasonally response characteristics of algal chlorophyll-a to total nitrogen (TN),total phosphorus (TP) and water temperature was investigated using quantile regression method.It indicated that water temperature was always the primary limiting factor of algal biomass indicated by chlorophyll a (Chl-a) across recent 24 years,but its limiting effect on algal Chl-a content was kept descending sharply and replaced much by nutrients (e.g.P,N) with the increasing eutrophic level.Especially the slope values of TP on Chl-a were kept ascending from -0.3 to 0.8.Since 2002,the positive effect of TN on Chl-a presented slow descending tendency,and P became the most important limiting nutrient factor of algal growth.According to the seasonal variation analysis,water temperature and N had dominant effects on algal Chl-a in spring and autumn,but they were replaced by P in the case of Chl-a>8 mg·m-3 in spring.In summer,N and P had strong interactive impacts on the algal growth,and the positive effect of P was stronger than that of N in the case of Chl-a>3 mg·m-3.In winter,algal biomass was co-limited by temperature and P.It suggested that P reduction is the prior choice of eutrophication control of Lake Erhai,and simultaneously reducing N load is necessary in the background of global warming.In addition,so far a emergency controlling measure should be taken to monitor algal blooming due to sharp ascending of water temperature within a few days in spring and autumn.

Co-composting of livestock manure with rice straw: characterization and establishment of maturity evaluation system.

Composting is considered to be a primary treatment method for livestock manure and rice straw, and high degree of maturity is a prerequisite for safe land application of the composting products. In this study pilot-scale experiments were carried out to characterize the co-composting process of livestock manure with rice straw, as well as to establish a maturity evaluation index system for the composts obtained. Two pilot composting piles with different feedstocks were conducted for 3 months: (1) swine manure and rice straw (SM-RS); and (2) dairy manure and rice straw (DM-RS). During the composting process, parameters including temperature, moisture, pH, total organic carbon (TOC), organic matter (OM), different forms of nitrogen (total, ammonia and nitrate), and humification index (humic acid and fulvic acid) were monitored in addition to germination index (GI), plant growth index (PGI) and Solvita maturity index. OM loss followed the first-order kinetic model in both piles, and a slightly faster OM mineralization was achieved in the SM-RS pile. Also, the SM-RS pile exhibited slightly better performance than the DM-RS according to the evolutions of temperature, OM degradation, GI and PGI. The C/N ratio, GI and PGI could be included in the maturity evaluation index system in which GI>120% and PGI>1.00 signal mature co-composts.