CLART: A cascaded lattice-and-radical transformer network for Chinese medical named entity recognition.

Chinese medical named entity recognition (NER) is a fundamental task in Chinese medical natural language processing, aiming to recognize Chinese medical entities within unstructured medical texts. However, it poses significant challenges mainly due to the extensive usage of medical terms in Chinese medical texts. Although previous studies have made attempts to incorporate lexical or radical knowledge in order to improve the comprehension of medical texts, these studies either focus solely on one of these aspects or utilize a basic concatenation operation to combine these features, which fails to fully utilize the potential of lexical and radical knowledge. In this paper, we propose a novel Cascaded LAttice-and-Radical Transformer (CLART) network to exploit both lexical and radical information for Chinese medical NER. Specifically, given a sentence, a medical lexicon, and a radical dictionary, we first construct a flat lattice (i.e., character-word sequence) for the sentence and radical components of each Chinese character through word matching and radical parsing, respectively. We then employ a lattice Transformer module to capture the dense interactions between characters and matched words, facilitating the enhanced utilization of lexical knowledge. Subsequently, we design a radical Transformer module to model the dense interactions between the lattice and radical features, facilitating better fusion of the lexical and radical knowledge. Finally, we feed the updated lattice-and-radical-aware character representations into a Conditional Random Fields (CRF) decoder to obtain the predicted labels. Experimental results conducted on two publicly available Chinese medical NER datasets show the effectiveness of the proposed method.

Application of Adjustable Skin Stretchers in Repairing Wound-Related Defects.

Objective: To explore the application value of adjustable skin stretchers for repairing skin wound defects. Methods: Twenty patients with skin defects were included in this study. The largest defect was measured to be 45.4 cm × 13.3 cm (length × width) and the smallest one was 4.4 cm × 3.2 cm (length × width). All patients were subjected to adjustable skin stretchers and the short- and long-term clinical efficacy was evaluated. Results: The wounds of all enrolled patients were healed completely except for one patient with a dorsal foot infection (the patient requested to return to the local county hospital for further treatment), with a total satisfaction of 100%. Postoperative 3-month follow-up showed scar formation, a little local hyperpigmentation, normal skin elasticity, and intact organs of involved cases, thus signifying the significant impact of adjacent joint activities. Conclusion: Adjustable skin stretchers can accurately control the tension on wound margins, breaking the limitation of previous stretchers to provide objective quantitative indicators for clinical application. These stretchers are characterized by high use-value and are worth promoting.

Effects of complex pollution by microplastics and heavy metals on soil physicochemical properties and microbial communities under alternate wetting and drying conditions.

Microplastics (MPs) broadly coexist with heavy metals (HMs) in soil, Cd and Cu are the main types of soil HMs contamination, in addition to polystyrene (PS), which is also widely present in the environment and prone to aging. However, differences in the effects of MPs and HMs on soil properties and microbial characteristics under alternating wetting and drying (AWD) remain unclear. Thus, this study investigated the effects of four conventional (0.2% (w/w)) and aged MPs in indoor incubation experiments on soil properties under desiccation (Dry) and AWD. We found that with the influence of the "enzyme lock" theory, the coexistence of MPs and HMs under Dry had a more pronounced effect on soil physicochemical properties, whereas the effects on soil enzyme activity under AWD were more significant. In addition, MPs decreased the available Cu by 4.27% and, conversely, increased the available Cd by 8.55%. Under Dry, MPs affected microbial function mainly through physicochemical properties, with a contribution of approximately 72.4%, whereas under AWD enzyme activity and HMs were significantly greater, with increases of 28.2% and 7.9%, respectively. These results indicate that the effects of MPs on environmental variation and microbial profiles under AWD conditions differed significantly from those under Dry.

Improvement of cadmium immobilization in contaminated paddy soil by using ureolytic bacteria and rice straw.

Cadmium (Cd) in paddy soil can be immobilized via microbially induced carbonate precipitation (MICP), but it poses a risk to the properties and eco-function of the soil. In this study, rice straw coupled with Sporosarcina pasteurii (S. pasteurii) was used to treat Cd-contaminated paddy soil with minimizing the detrimental effects of MICP. Results showed that the application of rice straw coupled with S. pasteurii reduced Cd bioavailability. The X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) confirmed that Cd immobilization efficiency was increased in the rice straw coupled with S. pasteurii treatment via co-precipitating with CaCO3. Moreover, rice straw coupled with S. pasteurii enhanced soil fertility and ecological functions as reflected by the high amount of alkaline hydrolysis nitrogen (AN) (14.9 %), available phosphorus (AP) (13.6 %), available potassium (AK) (60.0 %), catalase (9.95 %), dehydrogenase (736 %), and phosphatase (214 %). Further, the relative abundance of dominant phyla such as Proteobacteria and Firmicutes significantly increased when applying both rice straw coupled with S. pasteurii. The most significant environmental factors that affected the composition of the bacterial community were AP (41.2 %), phosphatase (34.2 %), and AK (8.60 %). In conclusion, using rice straw mixed with S. pasteurii is a promising application to treat Cd-contaminated paddy soil due to its positive effects on treating soil Cd as well as its ability to reduce the detrimental effects of the MICP process.

Conversion of swine manure into biochar for soil amendment: Efficacy and underlying mechanism of dissipating antibiotic resistance genes.

Livestock manure amendment, a common fertilization method for agricultural practice, can exacerbate antibiotic resistance gene (ARG) pollution, thus threatening food safety and human health. On the other hand, manure can also be produced as biochar to improve soil quality, which may reduce ARGs inside manure. However, it is unclear how and why shifting manure to biochar for soil amendment reduces ARG pollution. Thus, this study investigated the variations of ARGs and microbial communities in soil amended with swine manure (2 % and 5 %) and its biochar (2 % and 5 %) and then explored how shifting swine manure to biochar reduced ARG contamination. After 28 d incubation, ARG number in soil without amendment, manure-amended soils, and biochar-amended soils were 47, 112-136, and 43-52, respectively. ARG abundance in soil without amendment, manure-amended soils, and biochar-amended soils were 7.66 × 107, 4.32 × 109 - 1.42 × 1011, and 8.44 × 107-9.67 × 107 copies g-1 dry soil, respectively. Compared to manure-amended soils, its biochar amendments reduced ARG abundance by 2-4 orders of magnitude and ARG number by 70-93 in soil. Besides, manure amendment altered while biochar did not alter bacterial diversity and composition. The changed soil properties and mobile genetic elements (MGEs) could explain the changes in ARGs. Relative to manure amendments, its biochar amendments reduced mobile genetic elements (MGEs), Proteobacteria and Bacteroidetes in soil, which explained the reduced abundance and diversity of ARGs; however, the multidrug-resistance genes harbored in Proteobacteria and Bacteroidetes were still abundant in biochar-amended soil. This study suggests that converting manure to biochar as a soil amendment can help control the spread of manure ARGs.

Allelopathic effect of pyrogallic acid on cyanobacterium Microcystis aeruginosa: The regulatory role of nitric oxide and its significance for controlling harmful algal blooms (HABs).

Utilization of allelochemicals to inhibit overgrowth of toxic cyanobacteria is considered to be an environmentally friendly approach. However, the regulatory role of the signaling molecule nitric oxide (NO) on cyanobacteria under allelopathic stress remains unanswered. Here we demonstrate that the effect of NO on the cyanobacterium Microcystis aeruginosa depends on allelopathic stress of pyrogallic acid (PA). The experimental results revealed that general stimulation of M. aeruginosa by PA occurred within the concentration range 0.4-0.8 mg/L. In parallel with increasing concentration of PA (1.6-16.0 mg/L), the growth of M. aeruginosa was observed to decrease. The effect of NO on M. aeruginosa was evaluated by addition of the NO scavenger hemoglobin. In the stimulation stage, intracellular NO was seen to decreased to modulate the level of reactive oxygen species (ROS) and to maintain redox homeostasis of the cells. In the inhibition stage, the physiological characteristics of M. aeruginosa were changed significantly. Additionally, the accumulation of S-nitrosothiol by M. aeruginosa indicated that the high concentrations of PA induced nitric oxidative stress in M. aeruginosa. This study provides a new thought to understand the role of NO in controlling harmful algal blooms through the allelopathic effect of aquatic macrophytes.

Nitrogen addition may promote soil organic carbon storage and CO2 emission but reduce dissolved organic carbon in Zoige peatland.

With the increase of nitrogen (N) deposition, N input can affect soil C cycling since microbes may trigger a series of activities to balance the supply and demand of nutrients. However, as one of the largest C sinks on earth, the role of extra N addition in affecting peatland soil C and its potential mechanism remains unclear and debated. Therefore, this study chose the largest peatland in China (i.e., Zoige, mostly N-limited) to systematically explore the potential changes of soil C, microbes, and ecoenzymes caused by extra N input at the lab scale incubation. Three different types of soils were collected and incubated with different levels of NH4NO3 solution for 45 days. After incubation, N input generally increased soil organic C (SOC) but decreased dissolved organic carbon (DOC) in Zoige peatland soils. Moreover, CO2 and CH4 emissions were significantly increased after high N input (equal to 5 mg NH4NO3 g-1 dry soils). Through a series of analyses, it was observed that microbial communities and ecoenzyme activities mainly influenced the changes of different C components. Collectively, this study implied that the increasing N deposition might help C sequestration in N-limited peatland soils; simultaneously, the risk of increased CO2 and CH4 by N input in global warming should not be ignored.

Tetracycline adsorption trajectories on aged polystyrene in a simulated aquatic environment: A mechanistic investigation.

Microplastics (MPs) have attracted widespread attention as an organic class of pollutants as well as pollutant carriers in recipient aquatic ecosystems. In this study, tetracycline (TC) adsorption by polystyrene (PS), with multiple aging-based temporal changes in the adsorption mechanism, was observed. The results revealed that the pseudo-second-order model accurately predicted the TC adsorption kinetics for different types of PS. In addition, the isothermal adsorption processes fit the Freundlich model; however, their interactions were drastically weakened at lower temperatures or increasing salinities. Corresponding to the electrostatic interactions, adsorption TC was largely pH-dependent, with the maximum adsorbed TC content on the PS surface at a pH of 5 in an aqueous environment. More importantly, mechanistic studies have revealed that, compared to virgin PS, TC complexes with aged PS are principally controlled by hydrogen bonding and ionic interactions, followed by π-π, polar-polar, and van der Waals interactions. These findings will aid in understanding the insights of TC and aged PS interactions and the underlying interactive molecular forces, which will be advantageous for comprehending the real case scenario of inter-pollutant interactions and related environmental pollution.

The Dual Roles of Nano Zero-Valent Iron and Zinc Oxide in Antibiotics Resistance Genes (ARGs) Spread in Sediment.

Nanoparticles (NPs) are widely used and ubiquitous in the environment, but the consequences of their release into the environment on antibiotics resistance genes (ARGs), microbial abundance, and community, are largely unknown. Therefore, this study examined the effect of nano zero-valent iron (nZVI) and zinc oxide (nZnO) on tetracycline resistance genes (tet-ARGs) and class 1 integron (intI1) in sediment under laboratory incubation. The coexistence of NPs and tetracycline (TC) on tet-ARGs/intI1 was also investigated. It was found that nZVI and nZnO promoted tet-ARGs/intI1 abundance in sediment without TC but reduced the inducing effect of TC on tet-ARGs/intI1 in sediment overlaid with TC solution. Without TC, nZVI, intI1, and the bacterial community could directly promote tet-ARGs spread in nZVI sediment, while intI1 and bacterial abundance were the most directly important reasons for tet-ARGs spread in nZnO sediment. With TC, nZVI and bacterial community could reduce tet-ARGs abundance in nZVI sediment, while nZnO and bacterial community could directly promote tet-ARGs in nZnO sediment. Finally, these findings provided valuable information for understanding the role of NPs in promoting and reducing ARGs in the environment.

Aggregation, solubility and cadmium-adsorption capacity of CuO nanoparticles in aquatic environments: Effects of pH, natural organic matter and component addition sequence.

Nanoparticles (NPs), heavy metals and natural organic matter may co-exist in the water bodies. Currently, knowledge on their interaction effects on the behaviors and fates of NPs and heavy metal ions is rather limited, which is critical to comprehensively understand their environmental risk. In this study, the aggregation, solubility and Cd-adsorption of CuO NPs co-existing with humic acid (HA) and Cd2+ upon different solution pH and contact sequences were determined. In the ternary systems of CuO NPs, HA and Cd2+, pH was more important than the contact sequence of the components in affecting the NP aggregation, while the contact sequence was a predominant factor in determining the NP solubility. Pre-equilibration of CuO NPs and HA before addition of Cd2+ resulted in the highest solubility and lowest aggregation of the NPs, relative to other sequences of addition of the components. The adsorption capacity of CuO NPs for Cd-ions increased with an increasing pH value from 5 to 9. HA significantly enhanced the Cd-adsorption capacity of CuO NPs at pH 7 and 9, while at pH 5 a non-significant effect was observed. The results are helpful to better estimate the behaviors and fates of CuO NPs and Cd2+ when they coexisting in natural waters.

Adsorption of Cu2+ by UV aged polystyrene in aqueous solution.

Microplastics are the critical carriers of heavy metals in the environment. Thus, investigating the adsorption mechanisms between the microplastics and heavy metals is helpful to understand the migration and transformation pattern of the heavy metals in the environment. The adsorption of microplastics towards heavy metals can be largely affected by natural aging (e.g., UV-aging), environmental pH, and salinity. In this study, the adsorption of polystyrene (PS) towards Cu2+ and the effects of UV-aging, environment pH, and salinity on the adsorption were systematically investigated. The results show that the adsorption capacity of PS towards Cu2+ increased with the UV-aging time, as UV-aging increased the microcracks and oxygen-containing functional groups on the surface of the PS. Adsorption kinetics data followed the pseudo-second-order model, indicating that the interaction between PS and Cu2+ is chemical adsorption. Adsorption isotherms data could be well-described by both the Langmuir and Freundlich models, indicating that the adsorption was multilayer adsorption. As the solution pH and salinity can influence the surface charge of the PS, they could also affect the performance of the PS on Cu2+ adsorption. High pH facilitated the adsorption of PS towards Cu2+, while high salinity (above 1‰) inhibited the adsorption.

Distribution of microplastics in the sludge of wastewater treatment plants in chengdu, China.

Large amounts of microplastics can accumulate in wastewater treatment plants (WWTPs), and sludge disposal is suspected to be a major source of microplastics pollution in the environment. It is therefore important to investigate the distribution of microplastics in the sludge of each processing unit of WWTPs. However, little information is available on this topic in China. Accordingly, in this study, the abundance and characteristics of microplastics in the sludge of two WWTPs in Chengdu were investigated. The abundance of microplastics in the sludge samples ranged from 44.4 n·kg-1 to 750.0 n·kg-1. Microplastics were mainly divided into particles (32.16%), debris (28.14%) and fibers (17.08%) according to their shape, and the colors of the microplastics were mainly green (35.19%) and translucent (18.06%). The particle sizes were mainly larger than 1 mm in dimension. Polyethylene, polypropylene and polystyrene were the prevalent types of microplastics analyzed. Our results provide basic information for better understanding the characteristics of microplastics in sludge and for improving sludge treatment.

Biochar promotes arsenic sequestration on iron plaques and cell walls in rice roots.

The iron (Fe) cycle in the rice-soil system affects arsenic (As) uptake by rice. The effect of Fe on As uptake can be influenced by the addition of biochar, but has not been thoroughly investigated. In this study, the effects of maize straw-derived biochar (MB) on Fe and As translocation were determined by analysing the Fe and As concentrations in pore water, dithionite-citrate-bicarbonate (DCB) extracts, and rice plants. As-contaminated soils were supplemented with 0 or 1% biochar and 0 or 90 mg kg-1 P, and rice plants were grown for 70 d. Results indicated that biochar addition increased the concentrations of Fe and As in pore water, while P did not affect them. Additionally, biochar promoted the accumulation of Fe and As in roots. However, the rice biomass increased by 28% upon biochar addition, indicating that the rice plants became more tolerant to As toxicity with biochar. Specifically, biochar increased the root triphenyl tetrazolium chloride (TTC) reductive intensity, reduced the root H2O2 concentration, and promoted iron plaque (IP) formation. Moreover, the positive correlation between IP/DCB-extractable As and crystalline Fe on the rice root surface indicated that crystalline Fe appeared to be the determinant species of IP and played a central role in As segregation. In addition, biochar increased both crystalline Fe formation on the root surface and the Fe content in the cell wall, which enhanced As sequestration. Overall, rice could effectively tolerate As stress under biochar treatment since As could be retained on the root surface and root cell wall with MB.

Copper accumulation and physiological markers of soybean (Glycine max) grown in agricultural soil amended with copper nanoparticles.

Copper-based nanoparticles (NPs) display a strong potential to replace copper salts (e.g., CuSO4) for application in agricultures as antimicrobial agents or nutritional amendments. Yet, their effects on crop quality are still not comprehensively understood. In this study, the Cu contents in soybeans grown in soils amended with Cu NPs and CuSO4 at 100-500 mg Cu/kg and the subsequent effects on the plant physiological markers were determined. The Cu NPs induced 29-89% at the flowering stage (on Day 40) and 100-165% at maturation stage (on Day 100) more Cu accumulation in soybeans than CuSO4. The presence of particle aggregates in the root cells with deformation upon the Cu NP exposure was observed by transmission electron microscopy. The Cu NPs at 100 and 200 mg/kg significantly improved the plant height and biomass, yet significantly inhibited at 500 mg/kg, compared to the control. In leaves chlorophyll-b was more sensitive than chlorophyll-a and carotenoids to the Cu NP effect. The Cu NPs significantly decreased the root nitrogen and phosphorus contents, while they significantly increased the leaf potassium content in comparison with control. Our results imply that cautious use of Cu NPs in agriculture is warranted due to relatively high uptake of Cu and altered nutrient quality in soybeans.

The fate of antibiotic resistance genes and their influential factors during excess sludge composting in a full-scale plant.

The alteration of antibiotic resistance genes (ARGs) during sludge composting has been less studied in a full-scale plant, causing the miss of practical implications for understanding/managing ARGs. Therefore, this study tracked the changes of ARGs and microbial communities in a full-scale plant engaged in excess sludge composting and then explored the key factors regulating ARGs through a series of analyses. After composting, the absolute and relative abundance of ARGs decreased by 91.90% and 66.57%, respectively. Additionally, pathway analysis showed that MGEs, composting physicochemical properties were the most vital factors directly influencing ARGs. Finally, network analysis indicated that Proteobacteria, Bacteroidetes, Firmicutes, and Actinobacteria were the main hosts of ARGs. Based on these findings, it can be known that full-scale composting could reduce ARGs risk to an extent.

C:N:P stoichiometry responses to 10 years of nitrogen addition differ across soil components and plant organs in a subtropical Pleioblastus amarus forest.

How stoichiometry in different ecosystem components responds to long-term nitrogen (N) addition is crucial for understanding within-ecosystem biogeochemistry cycling processes in the context of global change. To explore the effects of long-term N addition on nutrient stoichiometry in soil and plant components in forest ecosystem, a 10-year N addition experiment using ammonium nitrate (NH4NO3) was conducted in a bamboo forest in the Rainy Zone of West China, where the background N deposition is the highest in the world. Four N treatment levels (+0, +50, +150, +300 kg N ha-1 yr-1) (CK, LN, MN, HN) were applied monthly since November 2007, and then, the C:N:P stoichiometry of soil, microbial biomass, and enzymes in rhizosphere soil and bulk soil, and plant organs were measured. N addition decreased the stoichiometry of C:N:P of soil, microbial biomass, and enzymes. Soil C:N:P change under N addition treatments was stronger in bulk soil, while C:N:P changes for microbial biomass and enzyme activity were significant in rhizosphere soil. N addition significantly decreased TOC in bulk soil. Changes in MBC:MBN:MBP in rhizosphere and bulk soil were mainly caused by MBN and MBP, and MBP performance was consistent with that of AP. The main variable leading to the change of enzyme C:N:P in rhizosphere soil was BG and AP, and in bulk soil was LAP + NAG activity. Plant root C:P and N:P increased with N addition, while those for leaves and twigs did not. N addition significantly reduced the pH of both rhizosphere and bulk soils. These results suggest that the stoichiometry responses of rhizosphere and bulk soils were different due to the influence of plant roots. Soil acidification, enhanced aluminum toxicity potential, decreased root biomass and enhanced microbial P limitation caused by N addition were the important mechanisms that promoted stoichiometry changes in this ecosystem. Under the chronic input of N deposition, the stoichiometry between plant and soil evolved in different directions, which may lead to the decoupling of plants from soils.

Dynamics of sediment phosphorus affected by mobile aeration: Pilot-scale simulation study in a hypereutrophic pond.

Controlling the release of phosphorus (P) in sediments is important to prevent eutrophication and harmful algal blooms in water bodies. Here we explored the effect of mobile aerators on the control of P release from sediments in a eutrophic pond. The dissolved oxygen in the water body recovered significantly after six months of aeration, becoming 4.2-5.8 times higher than in the control. The pH and Eh values at the sediment-water interface considerably increased, while the concentration of soluble reactive phosphorus (SRP) in pore water significantly decreased, resulting in the alteration of SRP fluxes from 1.69 mg/m2 d to -53.49 mg/m2 d. Moreover, the inert P in sediments increased by 5.2% of the total P at the end of the study compared with the initial state, and the calcium-bound phosphorus (HCl-P) increased by 96.6%. However, although aeration reduced the concentration of SRP in the water column, the total P concentration was 2.45 times higher than that of the control, and the content of redox-sensitive P (BD-P) in the sediment also increased by 200%. Overall, although mobile aeration can maintain the microenvironment of the sediment interface and increase the inert P content in the sediment to reduce the P flux, it cannot reduce the risk of release of mobile P.

Particle-Specific Toxicity of Copper Nanoparticles to Soybean (Glycine max L.): Effects of Nanoparticle Concentration and Natural Organic Matter.

For the soluble metallic nanoparticles (NPs), which forms (particles [NP(particle) ] vs. dissolved ions [NP(ion) ]) are the main cause of toxicity of the NP suspension (NP(total) ) remains uncertain. In the present study, soybean was exposed to Cu NPs in a hydroponic system to determine how natural organic matter (NOM; 10 mg/l) and concentration of Cu NP(total) (2-50 mg/l) affect the relative contributions of Cu NP(particle) and Cu NP(ion) to the overall toxicity. We found that NOM mitigated the phytotoxicity of Cu NP(particle) more significantly than that of Cu salt. When no NOM was added, Cu NP(particle) rather than Cu NP(ion) was the main contributor to the observed toxicity regardless of the concentration of Cu NP(total) . However, NOM tended to reduce the relative contribution of Cu NP(particle) to the toxicity of Cu NP(total) . Especially at a low concentration of Cu NP(total) (2 mg/l), the toxicity of Cu NP(total) mainly resulted from Cu NP(ion) in the presence of NOM (accounting for ≥70% of the overall toxicity). This might be attributable to the combined effects of increased dissolution of Cu NPs and steric-electrostatic hindrance between Cu NP(particle) and the soybean roots caused by NOM. Fulvic acids (FAs) tended to reduce the role of Cu NP(particle) in the overall toxicity more effectively than humic acids (HAs), which might partially be due to the higher extent of Cu NP dissolution on FA treatment than in HA treatment. Our results suggest that because of the relatively low metallic NP concentration and the presence of NOM in natural water, NP(ion) are likely problematic, which can inform management and mitigation actions. Environ Toxicol Chem 2021;40:2825-2835. © 2021 SETAC.

Elucidating the effects of TiO2 nanoparticles on the toxicity and accumulation of Cu in soybean plants (Glycine max L.).

Copper (Cu) pollution is common in the soil. Due to the widespread application of TiO2 NPs, there is a high propensity for the co-occurrence of TiO2 nanoparticles (NPs) and Cu in agricultural soils. It is therefore imperative to evaluate the joint effects of TiO2 NPs and Cu on crops. In this study, the mutual effects of TiO2 NPs and Cu on their toxicity and accumulation in soybean seedlings and on their fates in a hydroponic system were determined. When Cu was at levels of 1 and 2 mg/L, the co-occurring TiO2 NPs at a non-toxic concentration (10 mg/L) significantly enhanced the toxicity and accumulation of Cu and Ti in soybeans, and inhibited the translocation of Cu from soybean roots to shoots. However, when the Cu concentration for co-exposure was ≥ 5 mg/L, such mutual effects disappeared. The amount of Cu ions adsorbed onto TiO2 NPs after 48 h of co-exposure gradually increased from 31 to 118 mg/g when the Cu concentration was increased from 1 to 20 mg/L. The aggregation and sedimentation of TiO2 NPs were significantly increased after 48 h of co-exposure with the Cu at a concentration higher than 5 mg/L, as compared to the single TiO2 NPs exposure. The increasing aggregation and sedimentation might reduce the bioavailability of TiO2 NPs associated with the adsorbed Cu to soybeans, and consequently alleviate or even neutralize the enhanced toxicity and accumulation of Cu in soybeans exerted by the co-existing TiO2 NPs. Our results thus suggest that consideration of the impact of TiO2 NPs on the phytotoxicity of heavy metals, and specifically Cu, needs to be interpreted with care, and highlight the importance of integrating the interaction and fates of TiO2 NPs and metals into their risk assessment.

Highly efficient removal of phosphorus from agricultural runoff by a new akadama clay barrier-vegetated drainage ditch system (VDD) and its mechanism.

A vegetated drainage ditch (VDD) system is an effective management practice for removing excess phosphorus (P) from agricultural runoff. However, the maximization of P removing efficiency by VDD remains a challenge. In this study, new VDDs with akadama clay barriers (particle size of clay: 1-6 mm; height of barrier: 5-15 cm and length of barrier: 10-90 cm) were designed in lab scale, and the mechanism of phosphate removal by akadama clay was investigated. It was found that a new VDD with akadama clay barriers (particle size:1 mm; height:10 cm and length: 90 cm) exhibited the highest removal efficiency of total P (TP) (97.1%), particulate P(PP) (96.9%), and dissolved P (DP) (97.4%), respectively. The retained P was mainly adsorbed in akadama clay barrier sections, and a low concentration of P was observed in soil sections in the new VDD. The maximum adsorption capacity of phosphate to akadama clay was 5.06 mg/g at 298 K, and XPS analysis indicated that phosphate was adsorbed by the inner-sphere complexation formation with the metal elements (Al, Fe). This study indicates that the new VDD with akadama clay barriers is a promising technique to efficiently remove P from agricultural runoff and significantly minimize the risk of P release into streams through runoff.