Wetlands as a potential multifunctioning tool to mitigate eutrophication and brownification.

Eutrophication and brownification are ongoing environmental problems affecting aquatic ecosystems. Due to anthropogenic changes, increasing amounts of organic and inorganic compounds are entering aquatic systems from surrounding catchment areas, increasing both nutrients, total organic carbon (TOC), and water color with societal, as well as ecological consequences. Several studies have focused on the ability of wetlands to reduce nutrients, whereas data on their potential to reduce TOC and water color are scarce. Here we evaluate wetlands as a potential multifunctional tool for mitigating both eutrophication and brownification. Therefore, we performed a study for 18 months in nine wetlands allowing us to estimate the reduction in concentrations of total nitrogen (TN), total phosphorus (TP), TOC and water color. We show that wetland reduction efficiency with respect to these variables was generally higher during summer, but many of the wetlands were also efficient during winter. We also show that some, but not all, wetlands have the potential to reduce TOC, water color and nutrients simultaneously. However, the generalist wetlands that reduced all four parameters were less efficient in reducing each of them than the specialist wetlands that only reduced one or two parameters. In a broader context, generalist wetlands have the potential to function as multifunctional tools to mitigate both eutrophication and brownification of aquatic systems. However, further research is needed to assess the design of the generalist wetlands and to investigate the potential of using several specialist wetlands in the same catchment.

Development and performance evaluation of online monitors for near real-time measurement of total and water-soluble organic carbon in fine and coarse ambient PM.

In this study, we developed two online monitors for total organic carbon (TOC) and water-soluble organic carbon (WSOC) measurements in fine (dp < 2.5µm) and coarse (2.5µm < dp < 10µm) particulate matter (PM), respectively. Their performance has been evaluated in laboratory and field tests to demonstrate the feasibility of using these monitors to measure near real-time concentrations, with consideration of their potential for being employed in long-term measurements. The fine PM collection setup was equipped with a versatile aerosol concentration enrichment system (VACES) connected to an aerosol-into-liquid-sampler (AILS), whereas two virtual impactors (VIs) in tandem with a modified BioSampler were used to collect coarse PM. These particle collection setups were in tandem with a Sievers M9 TOC analyzer to read TOC and WSOC concentrations in aqueous samples hourly. The average hourly TOC concentration measured by our developed monitors in fine and coarse PM were 5.17 ± 2.41 and 0.92 ± 0.29 µg/m3, respectively. In addition, our TOC readings showed good agreement and were comparable with those quantified using Sunset Lab EC/OC analyzer operating in parallel as a reference. Furthermore, we conducted field tests to produce diurnal profiles of fine PM-bound WSOC, which can show the effects of ambient temperature on maximum values in the nighttime chemistry of the winter, as well as on increased photochemical activities in afternoon peaks during the summer. According to our experimental campaign, WSOC mean values during the study period (3.07 µg/m3 for the winter and 2.7 µg/m3 for the summer) were in a comparable range with those of earlier studies in Los Angeles. Overall, our results corroborate the performance of our developed monitors in near real-time measurements of TOC and WSOC, which can be employed for future source apportionment studies in Los Angeles and other areas, aiding in understanding the health impacts of different pollution sources.

Oxidation and mineralization rates of harmful organic chemicals in hydroxyl radical induced reactions.

In most of advanced oxidation processes (AOPs) used to destroy harmful organic chemicals in water/wastewater hydroxyl radical (•OH) reactions oxidize (increasing the oxygen/carbon ratio in the molecules) and mineralize (transforming them to inorganic molecules, H2O, CO2, etc.) these contaminants. In this paper, we used the radiolysis of water to produce •OH and characterised the rate of oxidation and mineralization by the dose dependences of the Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) content values. Analysis of the dose dependences for 34 harmful organic compounds showed large differences in the oxidation and mineralization rates and these parameters are characteristic to the given group of chemicals. E.g., the rate of oxidation is relatively low for fluoroquinolone antibiotics; it is high for ß-blocker medicines. Mineralization rates are low for both fluoroquinolones and ß-blockers. The one-electron-oxidant •OH in most cases induces two - four-electron-oxidations. Most of the degradation takes place gradually, through several stable molecule intermediates. However, based on the results it is likely, that some part of the oxidation and mineralization takes place parallel. The organic radicals formed in •OH reactions react with several O2 molecules and release several inorganic fragments during the radical life cycle.

Wastewater Characterization: Chemical Oxygen Demand or Total Organic Carbon Content Measurement?

The long time (2 h) required for measurement, expensive chemicals (Ag2SO4), and toxic reagents (K2Cr2O7, HgSO4) limit the application of the standard method for measuring the oxygen equivalent of organic content in wastewater (chemical oxygen demand, COD). In recent years, the COD has increasingly been replaced by the total organic carbon (TOC) parameter. Since the limit values of the pollution levels are usually given in terms of the COD, efforts are being made to find the correlation between these parameters. Several papers have published correlation analyses of COD and TOC for industrial and municipal wastewater, but the relationship has not been discussed for individual chemicals. Here, this relationship was investigated using 70 contaminants (laboratory chemicals, pharmaceuticals, and pesticides). The calculated COD values, in most cases, agreed, within ~10%, with the experimental ones; for tetracyclines and some chloroaromatic molecules, the measured values were 20-50% lower than the calculated values. The COD/TOC ratios were between 2 and 3: for macrolides, they were ~3; for fluoroquinolones and tetracyclines, they were ~2. The molecular structure dependence of the ratio necessitates the establishing of the correlation on an individual basis. In advanced oxidation processes (AOPs), the ratio changes during degradation, limiting the application of TOC instead of COD.

Partial wet oxidation of dairy manure as a pretreatment process to produce acetic acid 'a Source Growth of Methanogens'.

Wet oxidation can be an effective process for the pretreatment of complex biomass such as lignocellulose. However, studies on the use of wet oxidation for treating solid waste such as dairy manure are limited. The use of partial wet oxidation to convert dairy manure into low molecular weight carboxylic acids as final products were investigated. This work focuses on the performance of the sub-critical wet oxidation treatment of dairy cattle manure as a conversion/pretreatment process to release matter from the lignocellulosic fraction rather than a destructive process. The operating conditions were controlled at the short residence time and optimal temperature in the presence of oxygen under a pressure of 120 psi. The thermal hydrolysis under wet oxidation significantly affected conversion manure slurry into organic acids. The concentration of acetic acid reached 1778 mg L-1, achieved at 190°C (60 minutes reaction time) as the reaction temperature increased within the range of 150°C-200°C, total organic carbon was reduced and monomers in the process liquids decreased. On the other hand, soluble COD in process liquids increased with an increment in reaction temperature. The results provide insights into technical options to pretreat dairy manure to improve biochemical conversion yield.

Design, optimization, and evaluation of a wet electrostatic precipitator (ESP) for aerosol collection.

In this study, we developed, optimized, and evaluated in lab and field experiments a wet electrostatic precipitator (ESP) for the collection of ambient PM2.5 (particulate matter with aerodynamic diameter < 2.5 µm) into ultrapure water by applying an electrostatic charge to the particles. We operated the wet ESP at different flow rates and voltages to identify the optimal operating conditions. According to our experimental measurements, a flow rate of 125 lpm and an applied positive voltage of 11 kV resulted in a lower ozone generation of 133 ppb and a particle collection efficiency exceeding 80-90% in all size ranges. For the field tests, the wet ESP was compared with the versatile aerosol concentration enrichment system (VACES) connected to a BioSampler, a PTFE filter sampler, and an OC/EC analyzer (Sunset Laboratory Inc., USA) as a reference. The chemical analysis results indicated the wet ESP concentrations of metal and trace elements were in very good agreement with those measured by the VACES/BioSampler and PTFE filter sampler. Moreover, our results showed comparable total organic carbon (TOC) concentrations measured by the wet ESP, BioSampler, and OC/EC analyzer, while somewhat lower TOC concentrations were measured by the PTFE filter sampler, possibly due to the limitations of extracting water-insoluble organic carbon (WIOC) from a dry substrate in the latter sampler. The comparable TOC content in the wet ESP and BioSampler samples differs from previous findings that showed higher TOC content in BioSampler samples compared to those collected by dry ESP. The results of the Dithiothreitol (DTT) assay showed comparable DTT activity in the VACES/BioSampler and wet ESP PM samples while slightly lower in the PTFE filter samples. Overall, our results suggest that the wet ESP could be a promising alternative to other conventional sampling methods.

Climate plays a dominant role over land management in governing soil carbon dynamics in North Western Himalayas.

The soil carbon (C) dynamics is strongly influenced by climate and land-use patterns in the Himalayas. Therefore, soils under five prominent land use [e.g., maize (Zea mays), horticulture, natural forest, grassland, and wasteland] were sampled down up to 30 cm depth under two climatic conditions viz., temperate and subtropical to assess the impacts of climate and landuse on soil C dynamics. Results demonstrated that irrespective of land use, temperate soil contains 30.66% higher C than subtropical soils. Temperate soils under natural forests had the higher total organic carbon (TOC, 21.90 g kg-1), Walkley-Black carbon (WBC, 16.42 g kg-1), contents, and stocks (TOC, 66.92 Mg ha-1 and WBC, 50.24 Mg ha-1), and total soil organic matter (TSOM, 3.78%) concentration as compared to other land uses like maize, horticulture, grassland, and wasteland. Under both climatic conditions, maize land use had the lowest TOC 9.63, 6.55 g kg-1 and WBC 7.22, 4.91 g kg-1 at 0-15 and 15-30 cm soil depth, respectively. Horticulture land use had 62.58 and 62.61% higher TOC and WBC over maize-based land use under subtropical and temperate climatic conditions at 0-30 cm soil depth, respectively. However, soils of maize land use under temperate conditions had ∼2 times more TOC than in subtropical conditions. The study inferred that the C-losses is more in the subtropical soil than in temperate soils. Hence, the subtropical region needs more rigorous adoption of C conservation farming practices than the temperate climatic setting. Although, the adoption of C storing and conserving practices is crucial under both climatic settings to arrest land degradation. Horticultural land uses along with conservation effective soil management practices may be encouraged to restore more soil C and to improve the livelihood security of the hill populace in the North Western Himalayas.

Soil organic carbon fractionation of spoiled and unspoiled soils under different land use and land cover systems.

Alteration in land use and land cover is the key factor affecting the soil carbon fractions and its distribution. A study was carried out to estimate the carbon fractions in soils of agricultural, forest and pasture lands in two different areas separated on the basis of industrial activities (spoiled and unspoiled) to get an insight on the long-term soil carbon storage potential. The results showed that the mean values of the total organic carbon (TOC) and various fractions are significantly different between the land use types (p < 0.05). Irrespective of the land uses, the forest land showed significantly higher TOC (7.97) than agricultural land (6.98) and pasture lands (6.68). Further, evaluation of carbon management index (CMI) indicated that forest lands had highest CMI value compared to the other land uses. The spoiled area had significantly higher TOC and carbon fractions than their respective counterparts in the unspoiled area (p < 0.05) due to the negative industrial impact on soil biological processes. The PCA separates the sources of different carbon fractions and revealed an association of N (nitrogen) and K (potassium) with VL (very labile) and L (labile) fractions and the association of P (phosphorous) with stable R (recalcitrant) form. Therefore, it can be inferred from the present study that alterations in land use not only result in soil quality degradation but also trigger a reduction in potential for long term soil C sequestration.

Classic indicators and diel dissolved oxygen versus trend analysis in assessing eutrophication of potable-water reservoirs.

Potable source-water reservoirs are the main water supplies in many urbanizing regions, yet their long-term responses to cultural eutrophication are poorly documented in comparison with natural lakes, creating major management uncertainties. Here, long-term discrete data (June 2006-June 2018) for classical eutrophication water quality indicators, continuous depth-profile data for dissolved oxygen (DO), and an enhanced hybrid statistical trend analysis model were used to evaluate the eutrophication status of a potable source-water reservoir. Based on classical indicators (nitrogen, N and phosphorus, P concentrations and ratios; phytoplankton biomass as chlorophyll a, chl a; and trophic state indices), the reservoir was eutrophic to hypereutrophic and stoichiometrically imbalanced. Anoxia/hypoxia occurred for 7-8 months annually systemwide, even throughout the water column for days to weeks in some years; and elevated total ammonia (up to ~900 µg tNH3 L-1 ) in surface waters from late summer/fall through late winter/early spring suggested substantial internal legacy nutrient loading. These surprising DO and tNH3 phenomena may characterize many reservoirs in urbanizing areas, and the associated cascade of negative impacts may increasingly affect them under global warming. Total organic carbon (TOC), seasonally influenced by phytoplankton biomass, commonly exceeded 6 mg L-1 , which is problematic for potable-water treatment, and significantly trended up over time. Wet-year inflow dilution influenced an apparent decreasing trend in nutrients within the hypereutrophic upper reservoir, which receives most tributary inputs. Nevertheless, significant reservoirwide trends (increasing total phosphorus [TP], phytoplankton chl a, TOC) and mid- and/or lower region trends (increasing total nitrogen [TN], tNH3 , decreasing TN:TP ratios) suggest that water quality degradation from eutrophication has worsened over time. These findings support broadly applicable recommendations to strengthen protection of potable source-water reservoirs in urbanizing watersheds: (1) protective numeric water quality criteria are needed for TOC as well as TN, TP, and chl a; (2) continuous diel data capture more realistic DO conditions than traditional sampling, and can provide important insights for water treatment managers; and (3) assessment of reservoir eutrophication status to track management progress over time should emphasize classic indicators equally as statistical trends, which are highly sensitive to short-term meteorological forcing.

Occurrence, distribution and sources of phthalates and petroleum hydrocarbons in tropical estuarine sediments (Mandovi and Ashtamudi) of western Peninsular India.

The present study provides baseline information on the concentration levels, distribution characteristics and pollution sources of environmental contaminants, such as phthalic acid esters (PAEs or phthalates) and petroleum hydrocarbons in surface sediments of the tropical estuaries (Mandovi and Ashtamudi) from western Peninsular India. Total PAEs (∑5PAEs), hopanes, steranes and diasteranes concentrations from Ashtamudi estuary ranged from 7.77 to 1478.2 ng/g, n.d.-363.2 ng/g, n.d.-121.5 ng/g and n.d.-116.6 ng/g, respectively. Likewise, PAEs (∑6PAEs), steranes and diasteranes concentrations from Mandovi estuary ranged from 60.1 to 271.9 ng/g, 2.33-40.1 ng/g and 2.28-23.0 ng/g, respectively. The PAEs comprising di-isobutyl phthalate (DIBP), dibutyl phthalate (DBP), an isomer peak for DBP, di(2-ethylhexyl) phthalate (DEHP), di-isononyl phthalate were dominant in Ashtamudi estuary sediments, while PAEs including diethyl phthalate, DIBP, DBP and its isomer, DEHP, di(2-ethylhexyl) terephthalate were detected in the Mandovi sediment samples. The results of this study show an insignificant correlation of TOC with PAEs, and indicates that the varying spatial distributions of the PAEs in both the estuaries can be the result of discharge sources. The higher concentration of PAE congeners was noticed in Ashtamudi, a Ramsar wetland site, that can be attributed to land-based plastic waste. The petroleum biomarkers were abundantly present in Mandovi estuary due to anthropogenic activities such as boating and spillage from oil tankers. The findings of the present study will serve as a reference point for future investigation of organic contaminants in Indian estuaries, and calls for attention towards implementing effective measures in controlling the pervasion of the PAEs and petroleum biomarkers.

Catalytic and non-catalytic degradation of acetaminophen in supercritical water.

Pharmaceutical industrial wastewater is typical wastewater consisting of complex organic compounds with higher concentration, microbial toxicity, strenuous to deteriorate, and environmental threatening. The present work assesses the degradation of recalcitrant acetaminophen (ACM) by a green technology known as supercritical water oxidation (SCWO). Experiments were carried out in a continuous flow SCWO reactor by altering reaction conditions such as temperature 400-600 °C, oxidant coefficient (OC 0 to 3), and Fe(II) catalyst concentration (0.5 and 1 mg L-1) to study the technical feasibility of highly concentrated ACM. Liquid product analysis indicated the total organic carbon (TOC) removal efficiency could reach up to 99.5% without catalyst at 600 °C and 99.9% with Fe(II) at 500 °C. The addition of Fe not only suppressed the intermediate ring components but also promoted the formation of permanent gases via decarboxylation and reforming reactions. The reaction between Fe(II) and H2O2 in supercritical water is extremely fast, which has a direct impact on the system's operating conditions. The high activity exhibited by Fe(II) catalyst degraded the ACM completely at an operating condition of 500 °C. Maximum H2 fraction was attained without catalyst at 600 °C, OC 0.5, and with the catalyst at 500 °C, respectively, whereas, CO2 tends to rise significantly with both temperature and oxidant concentration. The catalytic process is efficient in comparison to the non-catalytic process. A possible reaction pathway was proposed based on the intermediates generated during the degradation.

Land-use systems regulate carbon geochemistry in the temperate Himalayas, India.

The Himalayan ecosystem is critical for ecological security and environmental sustainability. However, continuous deforestation is posing a serious threat to Himalayan sustainability. Changing land-use systems exert a tenacious impact on soil carbon (C) dynamics and regulate C emissions from Himalayan ecosystem. Therefore, this study was conducted to determine the changes in different C pools and associated soil properties under diverse land-use systems, viz. natural forest, natural grassland, maize field converted from the forest, plantation, and paddy field of temperate Himalaya in the surface (0-20 cm) and subsurface (20-40 cm) soils. The highest total organic carbon (24.24 g kg-1) and Walkley-black carbon contents (18.23 g kg-1), total organic carbon (45.88 Mg ha-1), and Walkley-black carbon stocks (34.50 Mg ha-1) were recorded in natural forest in surface soil (0-20 cm depth), while soil under paddy field had least total organic carbon (36.45 Mg ha-1) and Walkley-black carbon stocks (27.40 Mg ha-1) in surface soil (0-20 cm depth). The conversion of natural forest into paddy land results in 47.36% C losses. Among the cultivated land-use system, minimum C losses (29.0%) from different pools over natural forest system were reported under maize-filed converted from forest system. Land conversion causes more C losses (21.0%) in surface soil (0-20 cm depth) as compared to subsurface soil. Furthermore, conversion of forest land into paddy fields increased soil pH by 5.9% and reduced total nitrogen contents and microbial population by 28.0% and 7.0%, respectively. However, the intensity of total nitrogen and microbial population reduction was the lowest under maize fields converted from the forest system. The study suggested that the conversion of natural forest to agricultural land must be discouraged in the temperate Himalayan region. However, to feed the growing population, converted forest land can be brought under conservation effective maize-based systems to reduce C loss from the intensive land use and contribute to soil quality improvements and climate change mitigation.

A shift from chemical oxygen demand to total organic carbon for stringent industrial wastewater regulations: Utilization of organic matter characteristics.

From 2022, industrial wastewater discharge regulations in South Korea will replace chemical oxygen demand (CODMn) with total organic carbon (TOC). A shift from CODMn to TOC is a pioneering change in protecting water bodies from organic contaminants. However, several industries are struggling to meet these TOC requirements even though their effluents met the CODMn limits. Effluent CODMn/TOC ratios (1.28 ± 0.64) found in our study were lower than the CODMn/TOC coefficients (1.33-1.80) suggested by the Ministry of Environment in South Korea. Aliphatic and particulate organic matter contents in effluents likely influenced the CODMn/TOC ratio. Regardless of the industrial category, dissolved organic carbon often consists of low molecular weight neutrals, hydrophobic organic carbon, and protein-like substances in raw and treated industrial wastewaters. The present study also revealed that TOC and CODMn represented different organic matter fractions in the paper mill and oil refinery wastewater, whereas the industrial park wastewater showed similar dissolved organic matter characteristics. Specifically, CODMn was effective in the determination of humic content in paper mill wastewater but was underestimated in oil refinery wastewater. Additionally, only paper mill effluents exceeded the TOC requirements (4 of 6 samples) and required an additional post-treatment process owing to higher organic loads.

Ratoon rice with direct seeding improves soil carbon sequestration in rice fields and increases grain quality.

Increasing both carbon (C) sequestration and food production is essential for a sustainable future. However, increasing soil C sequestration or graining yield/quality in rice (Oryza sativa L.) systems has been a tradeoff in that pursuing one goal may compromise the other goal. Field experiments were designed to evaluate methane emission and grain yield in two rice systems in southern China, including the traditional double rice with a seedling transplanting system and innovative ratoon rice with a direct seeding system. Grain yield, grain quality, methane (CH4) emission, and total organic carbon (TOC) loss rate were investigated, and yield-scaled CH4 gas emission was assessed. It is found that double rice has a higher grain yield than ratoon rice. However, the grain quality (processing, appearance of chalkiness degree and chalky grain percentage, and nutritional quality) of ratoon rice is superior to double rice, especially the ratoon crop. The yield-scaled CH4 emission of ratoon rice (0.06 kg kg-1) decreased by 49.29% than double rice (0.12 kg kg-1) throughout the growth period. Compared with the TOC loss rate of double rice (2.95 g kg-1), the rate of ratoon rice was lower (1.97 g kg-1). As a result, ratoon rice with direct seeding can not only improve grain quality but also mitigate yield-scaled CH4 gas emission and TOC loss rate of rice fields. Therefore, we suggest to use ratoon rice with a direct seeding technique to promote agricultural C sequestration.

Online water quality monitoring based on UV-Vis spectrometry and artificial neural networks in a river confluence near Sherfield-on-Loddon.

Water quality monitoring is very important in agricultural catchments. UV-Vis spectrometry is widely used in place of traditional analytical methods because it is cost effective and fast and there is no chemical waste. In recent years, artificial neural networks have been extensively studied and used in various areas. In this study, we plan to simplify water quality monitoring with UV-Vis spectrometry and artificial neural networks. Samples were collected and immediately taken back to a laboratory for analysis. The absorption spectra of the water sample were acquired within a wavelength range from 200 to 800 nm. Convolutional neural network (CNN) and partial least squares (PLS) methods are used to calculate water parameters and obtain accurate results. The experimental results of this study show that both PLS and CNN methods may obtain an accurate result: linear correlation coefficient (R2) between predicted value and true values of TOC concentrations is 0.927 with PLS model and 0.953 with CNN model, R2 between predicted value and true values of TSS concentrations is 0.827 with PLS model and 0.915 with CNN model. CNN method may obtain a better linear correlation coefficient (R2) even with small number of samples and can be used for online water quality monitoring combined with UV-Vis spectrometry in agricultural catchment.

Evolution of Atmospheric Total Organic Carbon from Petrochemical Mixtures.

Reactive organic compounds play a central role in the formation of ozone and secondary organic aerosols. The ability to accurately predict their fate, in part, relies upon quantitative knowledge of the chemical and physical parameters associated with the total organic carbon (TOC), which includes both precursors and oxidation products that evolve in the atmosphere over short to long time scales. However, such knowledge, obtained via limited carbon closure experiments, has not been attained for complex anthropogenic emissions. Here we present the first comprehensive characterization of TOC in the atmospheric oxidation of organic vapors from light and heavy oil mixtures associated with oil sand operations. Despite the complexity of the investigated oil mixtures, we are able to achieve carbon closure (83-116%) within the uncertainties (±20%), with the degree of the closure being dependent upon the vapor composition and NOx levels. In contrast to biogenic precursors (e.g., α-pinene), the photochemical time scale required for a largely complete oxidation and evolution of chemical parameters is very long for the petrochemical vapors (i.e., ∼7-10 days vs ∼1 day), likely due to the lower initial precursor reactivity. This suggests that petrochemical emissions and their impacts are likely to extend further spatially than biogenic emissions, and retain more of their complex composition and reactivity for many days. The results of this work provide key parameters to regional models for further improving the representation of the chemical evolution of petrochemical emissions.

Recycling nutrient-rich hop leaves by composting with wheat straw and farmyard manure in suitable mixtures.

The harvesting of hops (Humulus lupulus L.) generates large amounts of nutrient-rich leaves that can be used in composting mixtures to add value to other organic resources on the farm. In this study, hop leaves were mixed with cow manure and wheat straw in several combinations with the aim of establishing guidelines on how farmers can manage the raw materials and better use these valuable organic resources. The composting process was monitored and the quality of the composts evaluated in relation to the effects on lettuce (Lactuca sativa L.) grown in pots over two consecutive cycles. The mixture of hop leaves with cow manure produced a stable compost after nine months of composting which may be used in horticultural crops, irrespective of the proportion of raw materials, due to their low and similar C/N ratios. However, when using mixtures of leaves and straw in proportions of less than 2:1, the composts did not mature properly, showing high C/N ratios. Their application to the soil led to a strong reduction in plant tissue N concentrations, due to biological N immobilization, which significantly reduced lettuce dry matter yield. Thus, to reduce composting time and increase the quality of the compost, the ratio leaves/straw should be as high as possible, at least 2:1. Alternatively, either the composting process should take longer, or the poorly-matured compost be applied far in advance of sowing a crop so that complementary biological processes can take place in the soil, as recorded in the second cycle of lettuce. Ash from hop stems did not benefit the composting process and proved itself not to be worth using in mixtures.

New insights on the removal of diclofenac and ibuprofen by CWPO using a magnetite-based catalyst in an up-flow fixed-bed reactor.

This research has been focused on the removal of two anti-inflammatory drugs, diclofenac (DCF) and ibuprofen (IBU), by a continuous catalytic wet peroxide oxidation (CWPO) process using a lab-synthesized nanomagnetic catalyst (Fe3O4/MWCNTs). The central composite rotatable design (CCRD) method was used to study the effect of DCF and IBU concentration (expressed as theoretical oxygen demand (ThOD) between 0 and 52.5 mg L-1) and of the feed stream pH (from 3 to 7) on the removal of total organic carbon (TOC) and the concentration of aromatic compounds (Arm) and total phenolic compounds (TP) by CWPO. It could be observed that DCF was preferably removed from the DCF-IBU aqueous mixture at pH values ranging from 3 to 5. In addition, feed stream pH had a significant effect on the pollutants removal, as well as on TOC, TP and aromatic compounds removal, observing an increasing in the pollutants degradation when feed stream pH decreased from 7 to 3. Quadratic models predicted for response variable, such as TOC, TP and aromatic compounds removal, and their maximum model-predicted removal values were of 90.0, 80.2 and 90.0%, respectively. Finally, as a proof of concept, three environmentally-relevant aqueous matrices, spiked with DCF-IBU mixture, were treated. In this case, relatively high TOC degradation values were found after 20 h reaction time (ca. 57.7, 73.9 and 54.5% in surface water, WWTP effluent and hospital wastewater, respectively). This work deals the first study about DCF-IBU removal in aqueous solution by CWPO, as well as a continuous study using real wastewater that allow to extend the experimental results to a real scenario.

Assessment of the total organic carbon employing the different nature-inspired approaches in the Nakdong River, South Korea.

Total organic carbon (TOC) has vital significance for measuring water quality in river streamflow. The detection of TOC can be considered as an important evaluation because of issues on human health and environmental indicators. This research utilized the novel hybrid models to improve the predictive accuracy of TOC at Andong and Changnyeong stations in the Nakdong River, South Korea. A data pre-processing approach (i.e., complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN)) and evolutionary optimization algorithm (i.e., crow search algorithm (CSA)) were implemented for enhancing the accuracy and robustness of standalone models (i.e., multivariate adaptive regression spline (MARS) and M5Tree). Various water quality indicators (i.e., TOC, potential of Hydrogen (pH), electrical conductivity (EC), dissolved oxygen (DO), water temperature (WT), chemical oxygen demand (COD), and suspended solids (SS)) were utilized for developing the standalone and hybrid models based on three input combinations (i.e., categories 1~3). The developed models were evaluated utilizing the correlation coefficient (CC), root-mean-square error (RMSE), and Nash-Sutcliffe efficiency (NSE). The CEEMDAN-MARS-CSA based on category 2 (C-M-CSA2) model (CC = 0.762, RMSE = 0.570 mg/L, and NSE = 0.520) was the most accurate for predicting TOC at Andong station, whereas the CEEMDAN-MARS-CSA based on category 3 (C-M-CSA3) model (CC = 0.900, RMSE = 0.675 mg/L, and NSE = 0.680) was the best at Changnyeong station.

A simplified approach to detect a significant carbon dioxide reduction by phytoplankton in lakes and rivers on a regional and global scale.

Carbon dioxide (CO2) uptake by phytoplankton can significantly reduce the partial pressure of CO2 (pCO2) in lakes and rivers, and thereby CO2 emissions. Presently, it is not known in which inland waters on Earth a significant pCO2 reduction by phytoplankton is likely. Since detailed, comparable carbon budgets are currently not available for most inland waters, we modified a proxy to assess the pCO2 reduction by phytoplankton, originally developed for boreal lakes, for application on a global scale. Using data from 61 rivers and 125 lakes distributed over five continents, we show that a significant pCO2 reduction by phytoplankton is widespread across the temperate and sub-/tropical region, but absent in the cold regions on Earth. More specifically, we found that a significant pCO2 reduction by phytoplankton might occur in 24% of the lakes in the temperate region, and 39% of the lakes in the sub-/tropical region. We also showed that such a reduction might occur in 21% of the rivers in the temperate region, and 5% of the rivers in the sub-/tropical region. Our results indicate that CO2 uptake by phytoplankton is a relevant flux in regional and global carbon budgets. This highlights the need for more accurate approaches to quantify CO2 uptake by primary producers in inland waters, particularly in the temperate and sub-/tropical region.