Identification of the co-existence of low total organic carbon contents and low pH values in agricultural soil in north-central Europe using hot spot analysis based on GEMAS project data

Total organic carbon (TOC) contents in agricultural soil are presently receiving increased attention, not only because of their relationship to soil fertility, but also due to the sequestration of organic carbon in soil to reduce carbon dioxide emissions. In this research, the spatial patterns of TOC and its relationship with pH at the European scale were studied using hot spot analysis based on the agricultural soil results of the Geochemical Mapping of Agricultural Soil (GEMAS) project. The hot and cold spot maps revealed the overall spatial patterns showing a negative correlation between TOC contents and pH values in European agricultural soil. High TOC contents accompanying low pH values in the north-eastern part of Europe (e.g., Fennoscandia), and low TOC with high pH values in the southern part (e.g., Spain, Italy, Balkan countries). A special feature of co-existence of comparatively low TOC contents and low pH values in north-central Europe was also identified on hot and cold spot analysis maps. It has been found that these patterns are strongly related to the high concentration of SiO₂ (quartz) in the coarse-textured glacial sediments in north-central Europe. The hot spot analysis was effective, therefore, in highlighting the spatial patterns of TOC in European agricultural soil and helpful to identify hidden patterns.

Potential impact of hydrodynamic shear force in aquifer thermal energy storage on dissolved organic matter releasement: A vigorous shaking batch study

The combination of bioremediation and aquifer thermal energy storage (ATES) has become attractive because of the possibility of solving environmental and energy problems simultaneously. While the impact of ATES on groundwater quality due to temperature change has received ample attention in literature, the effect of the greatly enhanced groundwater flow velocity on groundwater quality has not yet received sufficient scientific attention. To fill this gap in understanding, we conducted a simple yet straightforward experiment to illustrate the impact of hydrodynamic shear force due to the water flow by ATES on the release of dissolved organic matter, which can potentially be advantageous to bioremediation. Vigorous shaking conditions were applied to simulate the enhanced dynamics at the ATES well center and nearby. As the indicators of dissolved organic matter, COD and TOC concentrations were significantly impacted by shaking. COD increased from 5.4 mgO₂/L to 36.3 mgO₂/L during horizontal shaking. The maximum COD level was determined as 33.8 mgO₂/L during orbital shaking, while the TOC level was growing from 6.7 to 28.7 mg C/L. Meanwhile, redox potential (with initial level -100 mV) was decreasing to -450 mV synchronously with the elevating COD and TOC level. Temperature was also revealed as a significant factor in the organic matter releasement. Microbial iron reduction was deemed to occur, yet sulfate reduction was not initiated during the whole experiment. Eventually, the structure of the soil-water matrix has been changed due to the extensive hydraulic and particle collisions, resulting in blackish appearance and thicker layer of fine particles. Overall, the findings advance our understanding of the role of the ATES-induced water flow in the subsurface biogeochemistry and give insight into the perspective of the combination of bioremediation and ATES. In general, an increase in dissolved organic matter can be expected due to the increased shear force at high flow conditions in the ATES system.

AAZTA5/AAZTA5-TOC: synthesis and radiochemical evaluation with 68Ga, 44Sc and 177Lu

PURPOSE

AAZTA (1,4-bis (carboxymethyl)-6-[bis (carboxymethyl)]amino-6-methylperhydro-1,4-diazepine) based chelators were initially developed in the context of magnetic resonance imaging. First radiochemical studies showed the capability of AAZTA to form stable complexes with radiolanthanides and moderately stable complexes with ⁶⁸Ga. For a systematic comparison of the labelling capabilities with current diagnostic and therapeutic trivalent radiometals, AAZTA⁵ (1,4-bis (carboxymethyl)-6-[bis (carboxymethyl)]amino-6-[pentanoic-acid]perhydro-1,4-diazepine) was synthesized representing a bifunctional version with a pentanoic acid at the carbon-6 atom. To evaluate the effect of adding a targeting vector (TV) to the bifunctional chelator on the complex formation, AAZTA⁵-TOC was synthesized, radiolabeled and tested in comparison to the uncoupled AAZTA⁵.

METHODS

AAZTA⁵ was synthesized in a 5-step synthesis. It was coupled to the cyclic peptide TOC (Phe¹-Tyr³ octreotide) via amide bound formation. AAZTA and AAZTA⁵-TOC complex formations with ⁶⁸Ga, ⁴⁴Sc and ¹⁷⁷Lu were investigated at different pH, temperature and precursor amounts. Stability studies against human serum, PBS buffer, EDTA and DTPA were performed.

RESULTS

AAZTA⁵ and AAZTA⁵-TOC achieved quantitative labelling (> 95%) at room temperature in less than 5 min with all three nuclides at pH ranges from 4 to 5.5 with low precursor amounts of 1 to 10 nmol. [⁴⁴Sc]Sc-AAZTA⁵ complexes as well as [⁴⁴Sc]Sc-AAZTA⁵-TOC were completely stable. The ¹⁷⁷Lu complexes of AAZTA⁵ and AAZTA⁵-TOC showed high stability comparable to the ⁴⁴Sc complexes. In contrast, the [⁶⁸Ga]Ga-AAZTA⁵ complex stability was rather low, but interestingly, [⁶⁸Ga]Ga-AAZTA⁵-TOC was completely stable.

CONCLUSION

AAZTA⁵ appears to be a promising bifunctional chelator for ⁶⁸Ga, ⁴⁴Sc and ¹⁷⁷Lu with outstanding labelling capabilities at room temperature. Complex stabilities are high in the case of ⁴⁴Sc and ¹⁷⁷Lu. While [⁶⁸Ga]Ga-AAZTA complexes alone lacking stability, [⁶⁸Ga]Ga-AAZTA⁵-TOC demonstrated high stability. The latter indicates an interesting feature of [⁶⁸Ga]Ga-AAZTA⁵-labelled radiopharmaceuticals.

Objective assessment of the effects of tumor motion in radiation therapy

PURPOSE

Internal organ motion reduces the accuracy and efficacy of radiation therapy. However, there is a lack of tools to objectively (based on a medical or scientific task) assess the dosimetric consequences of motion, especially on an individual basis. We propose to use therapy operating characteristic (TOC) analysis to quantify the effects of motion on treatment efficacy for individual patients. We demonstrate the application of this tool with pancreatic stereotactic body radiation therapy (SBRT) clinical data and explore the origin of motion sensitivity.

METHODS

The technique is described as follows. (a) Use tumor-motion data measured from patients to calculate the motion-convolved dose of the gross tumor volume (GTV) and the organs at risk (OARs). (b) Calculate tumor control probability (TCP) and normal tissue complication probability (NTCP) from the motion-convolved dose-volume histograms. (c) Construct TOC curves from TCP and NTCP models. (d) Calculate the area under the TOC curve (AUTOC) and use it as a figure of merit for treatment efficacy. We used tumor motion data measured from patients to calculate the relation between AUTOC and motion magnitude for 25 pancreatic SBRT treatment plans. Furthermore, to explore the driving factor of motion sensitivity of a given plan, we compared the dose distribution of motion-sensitive plans and motion-robust plans and studied the dependence of motion sensitivity to motion directions.

RESULTS

Our technique is able to recognize treatment plans that are sensitive to motion. Under the presence of motion, the treatment efficacy of some plans changes from providing high tumor control and low risks of complications to providing no tumor control and high risks of side effects. Several treatment plans experience falloffs in AUTOC at a smaller magnitude of motion than other plans. In our dataset, a potential indicator of a motion-sensitive treatment plan is that the duodenum is in proximity to the tumor in the SI direction.

CONCLUSIONS

The TOC framework can serve as a tool to quantify the effects of internal organ motion in radiation therapy. With pancreatic SBRT clinical data, we applied this tool to study the change in treatment efficacy induced by motion for individual treatment plans. This framework could potentially be used clinically to understand the effects of motion in an individual patient and to design a patient-specific motion management plan. This framework could also be used in research to evaluate different components of the treatment process, such as motion-management techniques, treatment-planning algorithms, and treatment margins.

Study on an Online Detection Method for Ground Water Quality and Instrument Design

The online measurement of ground water quality, as one important area of water resource protection, can provide real-time measured water quality parameters and send out warning information in a timely manner when the water resource is polluted. Based on ultraviolet (UV) spectrophotometry, a remote online measurement method is proposed and used to measure the ground water quality parameters chemical oxygen demand (COD), total organic carbon (TOC), nitrate nitrogen (NO₃-N), and turbidity (TURB). The principle of UV spectrophotometry and the data processing method are discussed in detail, the correlated mathematical modeling of COD and TOC is given, and a confirmatory experiment is carried out. Turbidity-compensated mathematical modeling is proposed to improve the COD measurement accuracy and a confirmatory experiment is finished with turbidity that ranges from 0 to 100 NTU (Nephelometric Turbidity Unit). The development of a measurement instrument to detect the ground water COD, TOC, NO₃-N, and TURB is accomplished; the test experiments are completed according to the standard specification of China's technical requirement for water quality online automatic monitoring of UV, and the absolute measuring errors of COD, TOC, and NO₃-N are smaller than 5.0%, while that of TURB is smaller than 5.4%, which meets the requirements for the online measurement of ground water quality.

Baseline concentrations of mercury species within sediments from Qatar's coastal marine zone

Baseline concentration of total mercury (THg), organic extractable mercury and methylmercury (CH₃Hg) concentrations in sediments from the northeastern, eastern and southeastern parts of the Arabian Gulf were assessed. Surface sediments were collected from eleven stations from the coastal waters of Qatar. All analyses were performed on homogenised samples. Total mercury analysis was performed by Cold Vapour Atomic Absorption Spectrometry (CVAAS), and methylmercury was analysed by Cold Vapour Atomic Fluorescence spectrometry (CVAFS) after aqueous phase ethylation of the extracted samples. Total mercury (THg) in sediments varied from 8.0 μg/kg to 34.3 μg/kg. Methylmercury was detected in all stations and ranged from 1.46 μg/kg to 3.10 μg/kg accounting for 5.4% to 18.4% of total mercury. Total organic carbon (TOC) ranged from 0.16 to 0.72%, while Organic extractable mercury ranged from 1.55 μg/kg to 13.3 μg/kg. Analysis, the grain size within these sediments, was carried out previously paving the way for studying the influence of these parameters on the sedimentary mercury concentration. Speciation was also assessed, as were relations between the measured mercury fractions.

Electrochemical degradation of psychoactive drug caffeine in aqueous solution using graphite electrode

In this study, the electrochemical degradation of caffeine (1,3,7-trimethylxanthine) in aqueous solution by a graphite electrode was investigated. Electrochemical degradation was tested by the cyclic voltametry technique performed in the potential range of -1.0 to +1.0 V versus Ag/AgCl, which confirmed the electro-activity of the selected caffeine. The effects of the treatment process variables, such as initial pH, current density, electrolyte concentration and electrolysis time on the degradation of caffeine, were explored. During the various stages of electrolysis, parameters such as chemical oxygen demand (COD), total organic carbon (TOC) were analysed. The maximum COD and TOC removal efficiencies of 85% and 77% were achieved at neutral pH 7, operated at a current density of 5.1 mA/cm², electrolyte (Na₂SO₄) concentration of 0.1 M and at 240 min electrolysis time. From this study, it can be concluded that the electrochemical treatment process could effectively reduce the COD and TOC from the caffeine in aqueous medium. The degradation of the caffeine was confirmed by UV spectra, IR spectra and HPLC analysis.

RHBDF2-Regulated Growth Factor Signaling in a Rare Human Disease, Tylosis With Esophageal Cancer: What Can We Learn From Murine Models?

Tylosis with esophageal cancer syndrome (TOC) is a rare autosomal dominant proliferative skin disease caused by missense mutations in the rhomboid 5 homolog 2 (RHBDF2) gene. TOC is characterized by thickening of the skin in the palms and feet and is strongly linked with the development of esophageal squamous cell carcinoma. Murine models of human diseases have been valuable tools for investigating the underlying genetic and molecular mechanisms of a broad range of diseases. Although current mouse models do not fully recapitulate all aspects of human TOC, and the molecular mechanisms underlying TOC are still emerging, the available mouse models exhibit several key aspects of the disease, including a proliferative skin phenotype, a rapid wound healing phenotype, susceptibility to epithelial cancer, and aberrant epidermal growth factor receptor (EGFR) signaling. Furthermore, we and other investigators have used these models to generate new insights into the causes and progression of TOC, including findings suggesting a tissue-specific role of the RHBDF2-EGFR pathway, rather than a role of the immune system, in mediating TOC; and indicating that amphiregulin, an EGFR ligand, is a functional driver of the disease. This review highlights the mouse models of TOC available to researchers for use in investigating the disease mechanisms and possible therapies, and the significance of genetic modifiers of the disease identified in these models in delineating the underlying molecular mechanisms.

Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater

The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K₂Cr₂O₇), silver sulfate (AgSO₄), and mercury (HgSO₄) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K₂CrO₄) to generate the K₂Cr₂O₇ on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO₃) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L^-1 for APHA, and 4.95 and 16.95 mg L^-1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. ᅟ Graphical abstract.

Characterization of Cyclodextrin/Volatile Inclusion Complexes: A Review

Cyclodextrins (CDs) are a family of cyclic oligosaccharides that constitute one of the most widely used molecular hosts in supramolecular chemistry. Encapsulation in the hydrophobic cavity of CDs positively affects the physical and chemical characteristics of the guests upon the formation of inclusion complexes. Such a property is interestingly employed to retain volatile guests and reduce their volatility. Within this scope, the starting crucial point for a suitable and careful characterization of an inclusion complex is to assess the value of the formation constant (K_f), also called stability or binding constant. This task requires the application of the appropriate analytical method and technique. Thus, the aim of the present paper is to give a general overview of the main analytical tools used for the determination of K_f values for CD/volatile inclusion complexes. This review emphasizes on the advantages, inconvenients and limits of each applied method. A special attention is also dedicated to the improvement of the current methods and to the development of new techniques. Further, the applicability of each technique is illustrated by a summary of data obtained from the literature.

Cleaning verification: A five parameter study of a Total Organic Carbon method development and validation for the cleaning assessment of residual detergents in manufacturing equipment

A Total Organic Carbon (TOC) based analytical method to quantitate trace residues of clean-in-place (CIP) detergents CIP100^® and CIP200^® on the surfaces of pharmaceutical manufacturing equipment was developed and validated. Five factors affecting the development and validation of the method were identified: diluent composition, diluent volume, extraction method, location for TOC sample preparation, and oxidant flow rate. Key experimental parameters were optimized to minimize contamination and to improve the sensitivity, recovery, and reliability of the method. The optimized concentration of the phosphoric acid in the swabbing solution was 0.05M, and the optimal volume of the sample solution was 30mL. The swab extraction method was 1min sonication. The use of a clean room, as compared to an isolated lab environment, was not required for method validation. The method was demonstrated to be linear with a correlation coefficient (R) of 0.9999. The average recoveries from stainless steel surfaces at multiple spike levels were >90%. The repeatability and intermediate precision results were ≤5% across the 2.2-6.6ppm range (50-150% of the target maximum carry over, MACO, limit). The method was also shown to be sensitive with a detection limit (DL) of 38ppb and a quantitation limit (QL) of 114ppb. The method validation demonstrated that the developed method is suitable for its intended use. The methodology developed in this study is generally applicable to the cleaning verification of any organic detergents used for the cleaning of pharmaceutical manufacturing equipment made of electropolished stainless steel material.

Environmental risk assessment of selected organic chemicals based on TOC test and QSAR estimation models

Environmental risks of organic chemicals have been greatly determined by their persistence, bioaccumulation, and toxicity (PBT) and physicochemical properties. Major regulations in different countries and regions identify chemicals according to their bioconcentration factor (BCF) and octanol-water partition coefficient (Kow), which frequently displays a substantial correlation with the sediment sorption coefficient (Koc). Half-life or degradability is crucial for the persistence evaluation of chemicals. Quantitative structure activity relationship (QSAR) estimation models are indispensable for predicting environmental fate and health effects in the absence of field- or laboratory-based data. In this study, 39 chemicals of high concern were chosen for half-life testing based on total organic carbon (TOC) degradation, and two widely accepted and highly used QSAR estimation models (i.e., EPI Suite and PBT Profiler) were adopted for environmental risk evaluation. The experimental results and estimated data, as well as the two model-based results were compared, based on the water solubility, Kow, Koc, BCF and half-life. Environmental risk assessment of the selected compounds was achieved by combining experimental data and estimation models. It was concluded that both EPI Suite and PBT Profiler were fairly accurate in measuring the physicochemical properties and degradation half-lives for water, soil, and sediment. However, the half-lives between the experimental and the estimated results were still not absolutely consistent. This suggests deficiencies of the prediction models in some ways, and the necessity to combine the experimental data and predicted results for the evaluation of environmental fate and risks of pollutants.

Electro-oxidation of Ofloxacin antibiotic by dimensionally stable Ti/RuO2 anode: Evaluation and mechanistic approach

Present study investigates the potential of Ti/RuO₂ electrode for degradation and mineralization of Ofloxacin (OFLX) antibiotic from synthetic wastewater by electro-oxidation (EO) method, not reported earlier. Effects of various EO parameters such as applied current (I), initial pH, initial OFLX concentration (C₀) and supporting electrolyte concentration on %OFLX removal efficiency and %TOC removal efficiency were systematically studied and reported. Decay kinetics of OFLX by varying C₀ and applied I were also studied. Additionally, mineralization current efficiency and specific energy consumption of OFLX mineralization were evaluated. Moreover, mode of oxidation method involved (direct and/or indirect oxidation) was also explored. Major OFLX transformation products during EO were identified using UPLC-Q-TOF-MS, and possible degradation reaction mechanism was proposed. Furthermore, operating cost analysis was performed to check the economic feasibility of the EO process. The optimum pH and current (I) were found to be ≈6.8 (natural pH of OFLX wastewater) and 1 A, respectively. Mineralization current efficiency decreased from 7.8% to 4.9% with increase in I value from 0.25 to 1 A. ≈80% of OFLX removal in 30 min of electrolysis and 46.3% TOC removal in 240 min of electrolysis at I = 1 A were observed. Pseudo-first-order kinetic model best fitted the experimental data showing R² value ≈ 0.99 for all the C_o and applied I studied.

Results of the second national forest soil inventory in Germany - Interpretation of level and stock profiles for PCDD/F and PCB in terms of vegetation and humus type

Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) were detected in 86 humic topsoil layers and in a subset of 11 randomly selected top mineral forest soils at the depths of 0-5cm and 5-10cm collected from different federal states of Germany. The distribution of these persistent organic pollutants (POPs) in humic topsoils with respect to vegetation cover (coniferous vs. deciduous vs. mixed), total organic carbon (TOC), altitude and latitude data was investigated. There is cross correlation between the contents and TOC while the correlation with latitude indicates higher abundances of POPs in central Germany where there is high population density accompanied with industrial activities. The calculated stocks suggest that humus type (mor, mull, or moder) in conjunction with forest type can explain the relative POPs abundances in different soil layers. Generally, humic topsoils show highest contents of POPs compare to the two mineral soils with a ratio of 100:10:1. However, the stock humic layers of coniferous stands contribute about 50% to the total stock, whereas at deciduous stands the stock is mainly located in the upper mineral soil layer (0-5cm). The soil-water distribution coefficients (Kd) were calculated to estimate the potential translocation in the different soil types. The Kd values vary among the PCBs and PCDD/Fs congeners and are most variable for humic topsoils. There is pronounced chemical abundance in the top mineral soils with increasing Kd and this points to non-water bound transport processes for superlipophilic compounds.

Element-specific behaviour and sediment properties modulate transfer and bioaccumulation of trace elements in a highly-contaminated area (Augusta Bay, Central Mediterranean Sea)

High sediment contamination in the coastal area of Priolo Bay, adjacent to the highly-polluted Augusta Harbour, poses serious risks for the benthic communities inhabiting the area. Nevertheless, the transfer of trace elements and consequent bioaccumulation in the biota is an overlooked issue. This study aimed to assess the transfer and bioaccumulation patterns of As, Cd, Ni and Hg to the dominant macroalgae and benthic invertebrates of Priolo Bay. Results revealed different patterns among trace elements (TEs), not driven by sediment contamination but rather by element-specific behaviour coupled with sediment physicochemical properties. Specifically, As accumulated in macroalgae but not in invertebrates, indicating bioavailability of dissolved As only, and a lack of effective trophic transfer. Ni was confined to surface sediment and transfer to biota was not highlighted. Cd and Hg showed the highest concentrations in invertebrates and bioaccumulated especially in filter feeders and carnivores, revealing the importance of suspended particulate and diet as transfer pathways. Total organic carbon (TOC), fine-grained sediments and redox potential were the most important sediment features in shaping the sediment contamination spatial patterns as well as those of TE transfer and bioaccumulation. In particular, As and Cd transfer to macroalgae, and especially Hg bioaccumulation in benthic invertebrates was controlled by sediment properties, resulting in limited transfer and accumulation in the most contaminated stations.

The dynamics of mercury near Idrija mercury mine, Slovenia: Horizontal and vertical distributions of total, methyl, and ethyl mercury concentrations in soils

The distributions of the total mercury (T-Hg), methylmercury (MeHg), and ethylmercury (EtHg) concentrations in soil and their relationship to chemical composition of the soil and total organic carbon content (TOC, %) were investigated. Core samples were collected from hill slope on the right and left riverbanks of the Idrija River. Former smelting plant is located on the right bank. The T-Hg average in each of the core samples ranged from 0.25 to 1650 mg kg^-1. The vertical T-Hg variations in the samples from the left bank showed no significant change with depth. Conversely, the T-Hg varied with depth, with the surface, or layers several centimeters from the surface, tending to show the highest values in the samples from the right bank. Since the right and left bank soils have different chemical compositions, different pathways of mercury delivery into soils were suggested. The MeHg and EtHg concentrations ranged from n.d. (not detected) to 444 μg kg^-1 and n.d. to 17.4 μg kg^-1, respectively. The vertical variations of MeHg and EtHg were similar to those of TOC, except for the near-surface layers containing TOC greater than 20%. These results suggest that the decomposition of organic matter is closely related to organic mercury formation.

[Effects of Organic Carbon Content on the Residue and Migration of Polycyclic Aromatic Hydrocarbons in Soil Profiles]

The effects of total organic carbon content (TOC) on the migration of polycyclic aromatic hydrocarbons (PAHs) in the soil were investigated. This study analyzed the vertical properties of the concentrations and distributions of PAHs and TOC at various soil profiles from functionally different environmental regions including nature reserves, ploughs, orchards, farmlands, metropolitan areas, and industrial parks. The vertical migration properties of PAHs in soils were examined by conducting leaching experiments in soil columns. The concentrations of PAHs varied from region to region and showed strong, positive correlations with TOC in the same region. Furthermore, based on the leaching experiments, the transport abilities of PAHs were significantly influenced by TOC, although they could all be transported to the deep layers by TOC in soil columns. The downward migration of PAHs decreased with the increase in TOC and vice versa. The properties of the composition and structure of PAHs also had an obvious influence on their residues and migration in soil profiles at the same TOC conditions. In addition, the transport of PAHs was related to the amount of leaching water, the leaching time, and the additional PAHs.

Historical record of nutrients inputs into the Xin'an Reservoir and its potential environmental implication

The Xin'an Reservoir is an important water supply source and water conservation area for the Qiantang River. However, after the occurrence of the two algae blooms in 1998 and 1999, the safety of water quality has been put into question. In order to study the historical deposition of nutrients, sediment cores were collected in different regions from the Xin'an Reservoir. The stable isotopes δ¹³C and δ¹⁵N, nutrients, total organic carbon (TOC), and inorganic carbon (IC) in the sediment cores were determined. Radiometric methods (²¹⁰Pb and ¹³⁷Cs) were used to obtain sediment chronologies. Spatially, it was found that the average total nitrogen (TN) content in the upper 5 cm of sediments increased from 0.21% in the riverine zone, to 0.33%, and then to 0.57% in the lacustrine zone. The average TP content in the upper 5 cm increased from 0.67 g kg^-1 in the riverine zone, to 1.03 g kg^-1 in the estuary region, and then to 1.65 g kg^-1 in the lacustrine zone. In addition, TOC levels showed a distinct increase from 1.42% in the bottom to 5.97% in the surface of the lacustrine zone. These results demonstrated that although primary productivity and the input of nutrients constantly increased in recent years, algae blooms rarely occurred in the Xin'an Reservoir, due to "depth effect" and an aquatic environment protection-oriented fishery policy. However, high TOC flux and high bio-available phosphorus and nitrogen in surface sediment demonstrated that the reservoir is still confronted with the potential risk of algae blooms.

Developing polyetherimide/graphitic carbon nitride floating photocatalyst with good photodegradation performance of methyl orange under light irradiation

Polyetherimide-graphitic carbon nitride (PEI-g-C₃N₄) floating photocatalyst has been synthesized by using polyetherimide (PEI) as linker to bind graphitic carbon nitride (g-C₃N₄) together. XRD and XPS analysis for PEI-g-C₃N₄ show that the interaction between PEI and g-C₃N₄ does not disturb the structure of g-C₃N₄. FTIR, TEM and theoretical results suggest that the long chain PEI binds g-C₃N₄ particles together to form PEI-g-C₃N₄ via hydrogen bonding interaction. Based on photodegradation results of methyl orange (MO), PEI can not photodegrade MO and just works as linker in PEI-g-C₃N₄, while the photodegradation performance of PEI-g-C₃N₄ is from the contribution of g-C₃N₄. Total organic carbon (TOC) analysis show that nearly 47% organic carbon has been converted into inorganic carbon after photodegradation, suggesting that PEI-g-C₃N₄ can destroy both NN bond and aromatic rings in MO under light irradiation. The photodegradation efficiency (91%) of MO by g-C₃N₄ is higher than that (80%) by PEI-g-C₃N₄ with stirring. But, the photodegradation efficiency (37%) of MO by g-C₃N₄ is lower than that (55%) by PEI-g-C₃N₄ without stirring. This is the advantage of floating photocatalyst with respect to the powder photocatalyst since the former can utilize more solar energy than the latter when stirring is not available.

Chemical investigation and quality of urban dew collections with dust precipitates

The quality and chemical composition of urban dew collections with dust precipitates without pre-cleaning of the collecting surface WSF (white standard foil) were investigated for 16 out of 20 collected samples with collected volumes ranging from 22 to 230 ml. The collection period was from March to July 2015 at an urban area, Jubaiha, which is located in the northern part of the capital city Amman, Jordan. The obtained results indicated the predominance of Ca²⁺ and SO₄^2- ions (ratio 2.2:1) that originated from Saharan soil dust; where the collected samples were alkaline (mean pH = 7.35) with high mineralization (429.22 mg/L) exceeding the previously reported dew values in Amman-Jordan. A relocation of NaCl and to a less extent Mg²⁺ from sea to land by Saharan wind is indicated by the percent sea-salt fraction calculations (over 100 and 52, respectively). The collected samples exhibited high total organic carbon (TOC) values ranging from 11.86 to 74.60 mg/L, presence of particulate settled material with turbidity ranging from 20.10 to 520.00 NTU, and presence of undesired elements like boron (mean = 1.48 mg/L) that made it different in properties from other dew water collections at clean surfaces, and exceeding the standard limits for drinking water for these parameters set by Jordanian Drinking Water standards (JS286/2015)/WHO standard. The quality of this water is more close to that for raw or agricultural water but if it is meant to be used as potable source of water, at least sand and activated charcoal filters are needed to purify it.

Linking sedimentary total organic carbon to 210Pbex chronology from Changshou Lake in the Three Gorges Reservoir Region, China

The influences of total organic carbon (TOC) and total nitrogen (TN) on Lead-210 (²¹⁰Pb) dating have recently been of increasing concern in lacustrine research. Sediment core from Changshou Lake in the Longxi catchment was investigated for influence of TOC on ²¹⁰Pb dating. Lead-210 excess (²¹⁰Pb_ex), Cesium-137 (¹³⁷Cs) activities, TOC, TN, and particle size were measured. We proposed a dating index based on ¹³⁷Cs chronology and particle size distribution of the lake sediment profile and rainfall erosivities calculated from Longxi catchment metrological records. Increasing trends in TOC and TN were specifically caused by commercial cage fish farming after 1989. The statistically significant correlation between ²¹⁰Pb_ex activity, TOC (0.61, p = 0.04) and TN (0.51, p = 0.04), respectively explained post-1989 ²¹⁰Pb scavenging. The ²¹⁰Pb_ex activity was closely related with coupled peaks of TOC and TN from mass depth 5-10 g cm^-2. Higher TOC/TN ratio (8.33) indicated submerged macrophytes and native aquatic algal growth as main source of carbon from enhanced primary productivity because of massive fertilizer use and coherent climate warming. The study supported key hypothesis on vital role of fertilizer usage and algal derived TOC in controlling sedimentary ²¹⁰Pb_ex activity at Changshou Lake sediment. ¹³⁷Cs profile and erosive events as time markers provided reliable and consistent sedimentation rate of (1.6 cm y^-1). ²¹⁰Pb_ex activity decayed exponentially after peak at mass depth 5.68 g cm^-2. Therefore, violation of ²¹⁰Pb dating primary assumptions made it inappropriate for sediment dating at Changshou Lake. TOC content must be considered while using ²¹⁰Pb as dating tool for lake sediment profiles.

Correlation between degradation pathway and toxicity of acetaminophen and its by-products by using the electro-Fenton process in aqueous media

The evolution of the degradation by-products of an acetaminophen (ACE) solution was monitored by HPLC-UV/MS and IC in parallel with its ecotoxicity (Vibrio fischeri 81.9%, Microtox^® screening tests) during electro-Fenton (EF) oxidation performed on carbon felt. The aromatic compounds 2-hydroxy-4-(N-acetyl) aminophenol, 1,4-benzoquinone, benzaldehyde and benzoic acid were identified as toxic sub-products during the first stage of the electrochemical treatment, whereas aliphatic short-chain carboxylic acids (oxalic, maleic, oxamic, formic, acetic and fumaric acids) and inorganic ions (ammonium and nitrate) were well identified as non-toxic terminal sub-products. Electrogenerated hydroxyl radicals then converted the eco-toxic and bio-refractory property of initial ACE molecule (500 mL, 1 mM) and subsequent aromatic sub-products into non-toxic compounds after 2 h of EF treatment. The toxicity of every intermediate produced during the mineralization of ACE was quantified, and a relationship was established between the degradation pathway of ACE and the global toxicity evolution of the solution. After 8 h of treatment, a total organic carbon removal of 86.9% could be reached for 0.1 mM ACE at applied current of 500 mA with 0.2 mM of Fe²⁺ used as catalyst.

[Sedimentary Characteristics and Sources of Organic Matter in Sediments of Dianchi Lake]

Sediment columns in the southeast and east of Dianchi Lake were taken as the object of the study to determine ages by ²¹⁰ Pb dating method.The contents and sediment fluxes of total organic carbon (TOC) and n-alkanes of the sediments were investigated,and organic sources were tracked according to the relevant indexes of n-alkanes.The results indicated that TOC contents and sediment fluxes of two sampling sediments both presented an increasing trend on the whole;Sediment fluxes of n-alkanes varied as three stages:increasing period,decreasing period and re-increasing period.When the sediment fluxes of n-alkanes and TOC both went up,it showed that they had the same sources:sediments in the lake and carried by the rivers;From 1980s to the end of 20^th century,sediment fluxes of n-alkanes were going down while those of TOC were going up.This result means there was a big difference in the sources of n-alkanes and TOC.The bacteria and algae in the lake made a great contribution to n-alkanes while TOC was mainly influenced by sediments in the lake and carried by the rivers.n-alkanes of the two sampling sites both ranged from C₁₂ to C₃₅.Based on the basic features and relevant indexes of n-alkanes,we proposed that emergent plants made big contributions to the sources of organic matter in the sediments of Dianchi Lake,simultaneously,bacteria and algae had significant contributions to the sources of organic matter in shallow depth of Dianchi Lake.

Import of Soluble Proteins into Chloroplasts and Potential Regulatory Mechanisms

Chloroplasts originated from an endosymbiotic event in which a free-living cyanobacterium was engulfed by an ancestral eukaryotic host. During evolution the majority of the chloroplast genetic information was transferred to the host cell nucleus. As a consequence, proteins formerly encoded by the chloroplast genome are now translated in the cytosol and must be subsequently imported into the chloroplast. This process involves three steps: (i) cytosolic sorting procedures, (ii) binding to the designated receptor-equipped target organelle and (iii) the consecutive translocation process. During import, proteins have to overcome the two barriers of the chloroplast envelope, namely the outer envelope membrane (OEM) and the inner envelope membrane (IEM). In the majority of cases, this is facilitated by two distinct multiprotein complexes, located in the OEM and IEM, respectively, designated TOC and TIC. Plants are constantly exposed to fluctuating environmental conditions such as temperature and light and must therefore regulate protein composition within the chloroplast to ensure optimal functioning of elementary processes such as photosynthesis. In this review we will discuss the recent models of each individual import stage with regard to short-term strategies that plants might use to potentially acclimate to changes in their environmental conditions and preserve the chloroplast protein homeostasis.

Characterizing Ohio River NOM Variability and Reconstituted-Lyophilized NOM as a Source Surrogate

Natural organic matter (NOM) was collected, concentrated, and lyophilized on a monthly basis for 15 months to create a temporal NOM library and assess seasonal variability of untreated Ohio River water. Using fluorescence spectroscopy with parallel factor analysis, similar spectral components for both the ultrafiltered source water (UF1X) and reconstituted lyophilized NOM were observed in a two-component model throughout the study, with overall average emission and excitation wavelengths of 418 nm and 270 nm, respectively, for component 1 and 482 nm and 370 nm, respectively, for component 2. Fluorescence spectroscopy, high-pressure liquid chromatography-size exclusion chromatography, and elemental analysis indicated that the NOM was humic-like during the study with only small seasonal changes. Data from these analyses also demonstrated similarity between results for UF1X, reverse osmosis-concentrated NOM, and reconstituted- lyophilized NOM, validating the use of the reconstituted- lyophilized NOM as a surrogate for its source.