Microbial fuel cell (MFC) based toxicity biosensors have shown wide application prospects in environmental monitoring due to the superiority of low cost, real-time, simple operation and online automatic detection. It was summarized that the research status of MFC-based toxicity biosensors for detecting and warning of heavy metal ions in recent ten years. Main indicators of the functions of biosensors were introduced based on the principle of the MFC-based toxicity biosensors. The performance of the MFC detecting heavy metals was analyzed from five aspects including its configuration, membrane type, electrode material, control mode and inoculated microorganism. Furthermore, the following potential future research directions of MFC-based toxicity biosensors were prospected:(1) To screen the electricigens with good specificity, high sensitivity and fast recovery for the detection of a specific heavy metal ion; (2) To achieve the miniaturization and integration of biosensors based on the new material technology; (3) To realize the remote online real-time monitoring and intelligent of MFC-based toxicity biosensors by the combination with 5th-generation technology.

The ditch, as a special wetland ecosystem, has high redox capacity and greenhouse gas emission potential. Its prominent feature is frequent wetting-drying alternations and also greatly disturbed by human activities. The ditch wetlands is an important source of nitrous oxide (N₂O), while N₂O emissions from ditch wetlands are regulated by various physical and chemical factors, such as hydrological characteristics, vegetation species and loadings of exogenous nutrients. Here the available studies on the quantification approach of N₂O emissions from ditch wetlands done in China and worldwide were synthesized, thereby comparing the N₂O fluxes from rural sewage ditches and agricultural ditches in different regions. Furthermore, the spatial-temporal variations in N₂O emissions from ditch wetlands are analyzed and the key regulators underlying are explored. Overall, further studies are needed to well understand N₂O emissions and the regulators in ditch systems, in particular, investigations on capacity of nitrification-denitrification in ditch wetlands should be strengthened, for the environmental friendly management practices on ditches.

China is one of the world's largest producers and consumers of pesticides, including organochlorines, organophosphates and pyrethroids. Pesticides contamination in soil mainly occur in pesticide-producing sites and agricultural land. Among them, the levels of pesticides residues and organic solvents in the pesticide-producing sites have raised serious concerns. Chemical oxidation technique, due to its advantages on low cost and short remediation time, has gained increasing attention. However, the excessive use of strong oxidants might lead to deterioration of the physicochemical properties of the soil. Therefore, it is important to consider alternative greener chemical oxidants or oxidation techniques to further improve the current technology. This review focuses on the soil remediation of the pesticide-producing sites and summarizes both conventional and emerging chemical oxidation techniques. Future outlook on new oxidants, materials and techniques for soil remediation is also discussed.

With the rapid development of economy, heavy metal pollution of soil have become more and more serious. Among numerous remediation techniques, phytoremediation is one of the research hotspots in the field of soil remediation, which features low cost and less environmental disturbance. However, some hyperaccumulator plants are still limited by the cultivation technology and not in a fit state to generate economic benefits at present, which restricts the large-scale application of heavy metal contamination remediation. Therefore, researchers have begun to focus on finding some new remediation plants. Bamboo species have attracted attention in the phytoremediation of heavy metal contaminated soil in recent years. Recent studies have shown that bamboo species are highly tolerable to heavy metals in soil and capable of absorbing such heavy metals. Besides, they are characterized by high biomass, simple cultivation, high economic benefits and strong adaptability to environment. So, it can be inferred that bamboo demonstrates high application potential and huge application prospects in the phytoremediation of contaminated soil. The current states and progress of bamboo species in the phytoremediation of heavy metal contaminated soil are outlined systematically in this article, including the growth responses, accumulation and enrichment of heavy metals in bamboo species, transport characteristics of heavy metals, mechanisms of phytoremediation and strengthening measures. The advantages of bamboo species in growth and economy are analyzed in comparison with other remediation plants, which shows bamboo species are feasible to the phytoremediation of heavy metal contaminated soil. In view of the shortcomings of existing researches, the scientific reference and research trend on the phytoremediation of heavy metal contaminated soil are presented.

Dissolved organic matter (DOM) is an important component of carbon, nitrogen and phosphorus cycle in aquatic ecosystems, and the study of regulatory mechanisms of riverine DOM export by watershed characteristics will help to strengthen our understanding of the biogeochemical behavior of DOM transport through rivers to downstream water bodies, and provide a basis for improving eutrophication and ecological restoration of rivers and their downstream water bodies. To examine the spatial and temporal variation of DOM concentrations and its influence factors controlled by watershed characteristics, nearly one year's field surveys were carried out in 16 sub-catchments of South Tiaoxi River. The concentrations of dissolved organic carbon (DOC), dissolved organic nitrogen (DON), dissolved organic phosphorus (DOP) were measured and ten watershed characteristic factors, such as water temperature, discharge, area, gradient, elevation, percentage of five land use types (natural forest, Phyllostachys praecox forest, farmland, town and water body) in each sub-watershed area were extracted. The results showed that the concentrations of DOC and DOP increased from upstream to downstream, which were consistent with the variations of land use pattern and contamination status. DON concentrations were highest in subcatchments dominated with planted forest land (Phyllostachys praecox, a bamboo species) and increased with an intensive proportion of planted forest land. DOP concentrations were lower in summer and autumn than in spring and winter, which could be attributed to the uptake of phosphorus by aquatic organism. Principal component analysis (PCA) revealed that the landscape characteristics (such as land use patterns, gradient) had a stronger influence on DOM concentrations than hydrological regime (discharge, water temperature). DOM concentrations were lower in subcatchments by natural forest land than in subcatchments by other land uses (i. e., planted forest land, cropland, and residential land), indicating that human activities could cause an increase in DOM concentration. The results of multiple regression analysis showed that the proportion of urban area is the best predictor of DOM concentration, and although urban areas are small (average area is about 5%) and scattered, they are an important source of DOM in the watershed.

Ecosystem service has become an effective management agency to promote the harmony and unity of ecosystems and human society. The ecosystem service functions of food supply, water conservation, climate regulation and habitat quality of the Huaihe River Eco-economic Zone (HRECZ) were evaluated during the past 20 years by using market value method, water balance equation method, InVEST model and HSI model, respectively. The spatial-temporal variation and related reasons of four ecosystem services were analyzed. The results revealed that:The spatial pattern of ecosystem services in HRECZ exhibited great spatial heterogeneity; the distribution of food supply function had strong regional characteristics with respect to different provinces, and the good part of food supply service was shifting from northwest to southwest with noticeable temporal changes; For water conservation function, temporal variation was also obvious with increasing at early stage and then decreasing, and spatially, the maximum water source conservation amount of per unit grid area was 1 439.15 mm, whereas the minimum was only -407.65 mm; The cumulative carbon sequestration in HRECZ from 1995 to 2015 was 203.7 Tg, showing certain carbon sequestration function, and the sinking rate was fast at the early stage while becoming slowly progressively; The proportion of areas with good habitat quality in the HRECZ decreased, and the average score of habitat quality reached the maximum in 2005 and 2010, however, after then, it showed a downward trend. In the future, HRECZ should balance the spatial distribution of ecosystem services and the land to be developed. Cross-regional ecological protection and management cooperation should be carried with the guide of river basin governance. Suggestions are made available for the comprehensive development of HRECZ, and the protection, regulation and management of its ecosystem regulation.

The aim of this study was to identify the characterization of weed communities and difference of species diversity among counties in wet direct-seeding paddy rice-wheat rotation areas in northern Zhejiang Province. The weed species was investigated in eleven counties during September to October in 2018 and 2019 by using the sampling method of inverted "W" pattern with nine sampling points. The weed abundance, species diversity, breadth of ecological niche and overlap values of ecological niche were analyzed. The results show that there were 49 weed species belonging to 34 genera of 17 families, and most of them belong to Gramineae and Cyperaceae. There were two dominant weed species (Leptochloa chinensis and Echinochloa crus-galli var. mitis), eight regional dominant weed species (such as Ammannia multiflora, Ludwigia prostrate, Oryza sativa f. spontanea, Leersia hexandra), and thirty-nine normal weed species. Species richness index, Simpson's index and Shannon index in Tonglu County was higher than other counties, while Pielou index of Xiaoshan County was the highest. Hierarchical cluster analysis revealed that weed species in northern Zhejiang Province could be divided into four groups, including Hangzhou group, Huzhou group, Pinghu-Haining-Haiyan group and Xiuzhou-Jiashan group. Niche breadth analysis show that the main weed species such as A. multiflora and E. crus-galli var. mitis had higher niche breadth value. The niche overlap value analysis indicate that 91% of the 300 pairs having the niche overlap value that exceeded 0.7, which indicate that high ecological characteristics similarity exists in resource utilization between the two weed species.

As an engineer in ecosystem, dung beetles play a vital role in decomposition and organic matter transfer of dung pats in pastoral systems. A dung pat decomposition experiment were conducted in the typical steppe area of Inner Mongolia by setting up isolated mesocosms containing dung pats only (control, T0), dung pats with a dweller dung beetle species Aphodius sordecens (T1), dung pats with a tunneller dung beetle speceis Onthophagus gibbulus (T2), dung pats with both beetle species (T3), and only soil treatment(CK). The fluxes of CH₄, CO₂, N₂O and totle(CO₂) were determined during decomposition of cow dung pats under these treatments, and the relationship of the GHG emission fluxes with environmental factors were analysed. The results show that the greenhouse gas produced by cattle dung pats was mainly CO₂(T0, CO₂ Flux=2 106 mg·m^-2·h^-1), while CH₄(T0, CH₄ Flux=2.769 mg·m^-2·h^-1) and N₂O(T0, N₂O Flux=0.019 mg·m^-2·h^-1) were less. The addition of A. sordecens[T1, Totle(CO₂) Flux=2 657 mg·m^-2·h^-1] significantly increased the CO₂ fluxes (P<0.05), while addition of O. gibbulus[T2, Totle(CO₂) Flux=2 422 mg·m^-2·h^-1] or the addition of both beetle species[T3, Totle(CO₂) Flux=2 398 mg·m^-2·h^-1] did not significantly alter the GHG fluxes (P>0.05). The two beetle species of different functional types showed different effects on GHG emissions in the process of dung pats decomposition, depending on the decomposition time and environmental conditions. The presence of O. gibbulus (T2) reduced GHG emissions (P<0.05), but not for the presence of A. sordecens (T1) or both species (P>0.05) during the fresh dung pat period; while none of beetles had an impact on GHG emissions (P>0.05) during the dry dung pat period. The total GHG influx was positively correlated with soil temperature (P<0.001), while the influxes of CH₄ and CO₂ was higher at a moderate soil moisture (P<0.01). The results of the study suggest that under proper temperature and moisture conditions the GHG emissions could be promoted, and both dung beetle species, regardless of their functional types, could have influence on GHG emissions from dung pats in different time.

To improve Cd²⁺ adsorption ability of biochar in aqueous solution, NaOH- and FeCl₃-modified biochars (NBC1, NBC2 and FBC1, FBC2) were prepared based on two kinds of original rice husk-derived biochars (BC1, BC2). Moreover, Cd²⁺ adsorption performances of the six materials were explored by the kinetics and isothermal adsorption experiments. Results show that Cd²⁺ equilibrium adsorption capacities of BC1 and BC2 were 14.76 and 13.72 mg·g^-1 under the condition of Cd²⁺ concentration 50 mg·L^-1 and biochar dosage 1 g·L^-1, respectively. NaOH-modification enhanced the Cd²⁺ adsorption ability of rice husk-derived biochars consistently and significantly, and the equilibrium adsorption capacities of NBC1 and NBC2 were 3.26 and 2.47 times that of BC1 and BC2, respectively. However, FeCl₃-modification had little effect on Cd²⁺ adsorption of the biochars, and the equilibrium adsorption capacities of FBC1 and FBC2 were only 1.03 and 0.74 times that of BC1 and BC2. The process of Cd²⁺ adsorption onto the original and modified rice husk-derived biochars was more consistent with the pseudo-second-order model and the Langmuir model, and it was assumed that the adsorption mainly occurs in monolayers. The maximum adsorption capacities of NBC1 and NBC2 (131.58 and 98.04 mg·g^-1, respectively) were significantly higher than that of FBC1 and FBC2 (30.30 and 23.26 mg·g^-1, respectively). The reason for Cd²⁺ adsorption capacity enhancement of NaOH-modified biochars is that NaOH-modification increased the amount of alkaline oxygen-containing functional groups on the surface of biochars, which enhances biochars' cation exchange and precipitation capacity with Cd²⁺.

A sand culture experiment was conducted to study the effects of dissolved organic matter (DOM) with different molecular weights and concentrations on the growth and Cu absorption of Chinese cabbage. The DOM extracted from pig manure was fractionated into three molecular weight components as F₁(<1 kDa), F₂(1-14 kDa) and F₃(>14 kDa) by means of equilibrium dialysis. Results suggest that, compared to the control (ultra-pure water), DOM application treatments increased the total root length and the number of root tips of Chinese cabbage by 19%-40% and 45%-91%, respectively, but no significant change was observed for the yield. Furthermore, DOM enhanced the absorption of Cu by Chinese cabbage roots, and Cu concentrations in roots increased with the application amount of DOM in the same molecular weight component. Compared to the control, treatment with 20 mg·L^-1 of F₁, F₂ and F₃ mixed with 2.5 mg·L^-1 of CuSO₄(F₁₃, F₂₃ and F₃₃) increased Cu concentrations in roots by 41%, 37% and 53% (P<0.05), respectively. Moreover, the treatment of F₁₃, F₂₃ and F₂₂(10 mg·L^-1 of F₂ mixed with 2.5 mg·L^-1 of CuSO₄) significantly promoted Cu upward translocation from roots, with the increments in translocation factors of 36%, 48% and 46%, respectively, compared with the control. However, F₃₃ decreased that translocation factor by 26%. Therefore, the molecular weight and addition amount of DOM can both impact Cu uptake and translocation of Cu in Chinese cabbages, low molecular weight of DOM with high concentration will enhance the accumulation and translocation of Cu.

Using reed and corn straw as raw materials, different biochars were prepared by orthogonal experimental design and applied to the remediation of Cd- and Pb-contaminated soils to find out the best preparation technique of biochar. The results show that carbonization temperature was the most important factor for the preparation of biochar. The yield of biochar decreased with the increase of temperature, while the pH and ash content of biochar increased. The specific surface area of biochar increased as temperature rising in a certain range. Other factors such as the moisture content, heating rate, and carbonization time of raw materials had less effect on the preparation of biochar compared with carbonization temperature. The yield of reed straw biochar (LWC) and corn straw biochar (YMC) was similar, the pH value and ash content of YMC was higher than that of LWC, and the specific surface area of LWC was higher than that of YMC. Considering the optimum level of factors and efficiency, the optimum pyrolysis condition for the preparation of LWC and YMC was found to be the same with moisture content of 25%, heating rate of 20℃·min^-1, carbonization temperature of 600℃, and carbonization time of 0.5 h. Compared with the control, the application of LWC and YMC increased the soil pH. Additionally, the immobilization efficiency of Cd and Pb increased with the incubation time. At 35 days, the contents of available Cd and Pb in soils maximally decreased by 51.7% and 44.9% with the addition of biochar. The inactivating effect of LWC to Cd and Pb in soils is better than that of YMC. The present research provides a technical support for the engineering preparation of biochar and a theoretical basis for the remediation of heavy metals in soils.

Microbial technology is a promising method for removing polycyclic aromatic hydrocarbons (PAHs) from contaminated soil. The PAHs degradation efficiency in the biopile treated contaminated soil was studied. 4 biopiles were set up, the control group (1#), the sufactants Tween 80 added one (2#), the ventilated one (3#) and the one mixed with the sufactants Tween 80 and ventilated (4#). The results show that after 9 days, the total PAHs in all experimental groups decreased by more than 80%. The low molecular weight PAHs (2-3 rings) levels decreased the most (91%) after 9 days, yet the medium and high molecular weight PAHs (4-6 rings) levels may take longer time to be degraded, and only 60% was degraded. The removal rates of the medium and high molecular weight PAHs were not significantly promoted via adding surfactant or ventilating after 80 days treatment. At the 31 days, the 3# and 4# groups were both mixed with the indigenous bacterial consortium enriched from the studied contaminated soil. The microbial community, surfactant and ventilating did not significantly promote the PAHs degradation rate in the studied period (80 days), although the dehydrogenase activities at 80 days of the 3# and 4# groups increased 7-fold and 9-fold respectively as compared with 41 days. At the 80 days, the dehydrogenase activities of 4# group reached 10 740 μg·g^-1·h^-1. This study verified the effectiveness of biopile in treating PAHs contaminated soil, explored the different treatement strengthening strageties for improving the remediation effect of biopile on PHA contaminated soil, and provided important information for the application of biopile in remediation of PAHs contaminated sites.

Chlorinated hydrocarbons are among the most common pollutants at industrial sites and have been detected widespreading in both soil and groundwater. Because of their environmental persistence and toxicities, there is a growing interest in developing new technologies for the removal of chlorinated hydrocarbons in the environment. The degradation of a typical chlorinated hydrocarbon, trichloroethane (TCE) by hydrogen peroxide (H₂O₂) was studied by using an iron-loaded zeolite (Fe-ZSM-5) as heterogeneous catalyst. In the Fe-ZSM-5/H₂O₂ system, the removal rate of TCE (0.9 mmol·L^-1) reached 88% with 0.8 g·L^-1 Fe-ZSM-5 and 10 mmol·L^-1 H₂O₂ at initial pH 7.4 and ambient temperature. And with the increasing of catalyst dosage and H₂O₂ concentration, the removal rate of TCE gradually increased, and the removal rate could reach up to 99%. In addition, initial pH had minor effect on the degradation of TCE. Compared with Fe-ZSM-5, the degradation rate of TCE was only 41% by ZSM-5 without iron loading, and the removal rate decreased when H₂O₂ concentration increased from 6 mmol·L^-1 to 14 mmol·L^-1, while the initial pH had also a minor effect on the removal rate of TCE. The results of free radical quenching experiment show that ·OH played a major role in the degradation of TCE in Fe-ZSM-5/H₂O₂ system, which was largely absent in ZSM-5/H₂O₂ system.

Taking the lakes in the Lieshi Park of Hunan Province as the research objects and relative humidity and wind speed as evaluation indicators, the relationship between lake factor (indexes of lake area and form) and the humidification effect of the lake in summer was studied by using field measurement in combination with computational fluid dynamics (CFD) simulation. The results indicate that (1) Under the influence of dominant wind direction in summer, the order of different regions of the study area was downwind, vertical wind and upwind successively in terms of the overall relative humidity from high to low, and the humidification effect was significant within 1 500 m away from the lake; (2) The humidification effect of the lake was positively correlated with index of lake area but negatively correlated with index of lake form and distance, among which index of lake area was the most significant factor. When lake area was reduced to 0, the relative humidity in the downwind region was significantly affected with a decline of 7.4-8.2 percentage point, and that of the central lake region decreased by 15.1-15.5 percentage point; When lake area was reduced by a half, the relative humidity in the downwind region decreased by 2.3-3.0 percentage point, and correspondingly the humidification effect of the lake was weakened. (3) When lake area remained unchanged but the index of lake form was increased, the underlying surface of the lake and water in the lake changed, and some regions of the lake were affected. When the index of lake form was increased by 1.5 times of the actual example, the relative humidity in the downwind region decreased by 0.6-1.3 percentage point; when the index of lake form was increased to be twice as much as the actual example, the relative humidity in the downwind region decreased by 1.7-2.2 percentage point. This study is of great significance for providing references to the improvement of the microclimate around urban lakes and for the future urban lake planning and construction.

Silicon (Si) and nitrogen (N) play an important role in the growth and development of rice. Appropriate application of silicon and nitrogen fertilizer is of great significance to improve the nutrient management and yield and quality of rice. A field experiment was conducted to explore the effects of different nitrogen fertilizer levels (120, 180, 240 kg·hm^-2, respectively, N1, N2, N3) and silicon fertilizer levels (0, 225, 450 kg·hm^-2, respectively, Si1, Si2, Si3) on nutrient element concentrations in leaves, yield components and quality of two rice cultivars Gui-nong-zhan and Huang-hua-zhan. The results show that Si and N fertilizer application could significantly increase nitrogen concentration in rice leaves at tillering stage and heading stage. At heading stage, compared with N1-Si1, N1-Si3 treatment increased nitrogen concentration in leaves of Gui-nong-zhan and Huang-hua-zhan by 17.0% and 44.4%, respectively. Si and N treatment significantly increased phosphorus concentration in leaves of Huang-hua-zhan at heading stage and Si concentration of two cultivars at tillering and heading stages. N and Si fertilizer significantly improved Si concentration in leaves at tillering and heading stage. Higher N and Si fertilization level resulted in higher yield for both cultivars. Treatments of N2-Si1 and N3-Si3 had the highest yield of Gui-nong-zhan and Huang-hua-zhan, which is 8 188.5 and 8 260.5 kg·hm^-2, respectively. Si application improved head rice rate in grains of both cultivars, while reduced amylase content, which is beneficial to rice quality improvement. The above findings suggested that the combination of low N and high Si, or medium N and low Si treatment are appropriate for plant growth, yield and quality improvement of Gui-nong-zhan.

To reveal the characteristics and differences of reconstructed soil bulk density in different profiles of the reclaimed land, the southern dump, western dump, expanded western dump and internal dump of the Antaibao open pit mine in Pingshuo were taken as the research objects, the differences of reconstructed soil bulk density were analyzed, and the relationship between dielectric constant and reconstructed soil bulk density was established by using the methods of ring knife sampling weighing, ground penetrating radar detection, variance analysis, and fitting analysis. The results show that:(1) The reconstructed soil bulk density had significant differences in different dumps and different depths of the same profile. (2) The differences of reconstructed soil bulk density in different dumps was qualitatively analyzed based on the large amplitude signal on the ground penetrating radar images. (3) The reconstructed soil bulk density (y) increased linearly with the change of the dielectric constant (x) when soil volumetric water content was less than 15%, and the fitting function was y=0.054 3x+1.019 2, R²=0.508 3, P=0.001. Ground penetrating radar has the popularization and application value in detecting reconstructed soil bulk density and the development of the non-destructive quality testing of land reclamation.