In order to scientifically identify and evaluate the soil heavy metal pollution and ecological risk in the background area with high heavy metal contents, 309 sets of maize and rhizosphere soil samples were collected in Hezhen Town of Hezhang County of Guizhou Province, and 20 maize samples from different parts of roots, stems and leaves were collected. The contents of heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were analyzed in topsoil and maize samples. Also, speciations of heavy metals in the rhizosphere soil samples were analyzed (Cr was not measured). The results showed that the contents of heavy metals in the soils were relatively high, and the averages were remarkably higher than the national soil background value (NBV), and the content of Cd element was nearly seven times higher than the NBV. The soil was mainly acidic, and the ecological risk was high based on the total amount of heavy metals. Speciation analysis indicated that heavy metals (As, Cu, Hg, Ni, Pb, and Zn) mainly existed in the forms of strong organic binding state and residual state, with low bioavailability, and the bioavailability of Cd was high. The ecological risk was mainly caused by Cd based on speciation of heavy metals. In the soil-corn system, the bioconcentration factors and translocation factors were both low, so heavy metals were difficult to be enriched in the corn. The contents of heavy metals in corn seeds did not exceed the standard, and the crops were safe. The above results provide a theoretical basis for further studying the migration and transformation law of heavy metals in rock-soil-gas-biota media, integrating geology, pedology and biology to establish a unified standard, and scientifically evaluating the ecological environment risk and health risk.

To improve the degradation efficiency of cellulose distributed in livestock, poultry wastes and garden wastes, a high-efficiency cellulose-degrading fungus which was from bamboo shavings, dead branches, and rotted leaves, and sheep dung was screened with Congo red staining, filter paper disintegration test and the endoglucanase [carboxyl methyl cellulose (CMC)] activity was tested. The physiological and molecular identification of the strain was carried out. The results showed that a high-efficiency cellulose-degrading fungus was screened in this study, which was identified as Trichoderma longibrachiatum by morphological observation and fungus species identification, and named as T. longibrachiatum ZJ-10. Single factor test showed that the conditions for achieving the maximum enzyme production activity showed as follows: 3% inoculation, initial pH 6.5, rotation speed of 160 r/min, 40 ℃, and cultured for 5 d. According to Plackett-Burman experimental design, Box-Benhnken steepest climbing path method and response surface methodology, the optimal enzyme production medium formula was 5 g/L NaCl, 7 g/L peptone, and 12 g/L CMC-Na. Under the optimal conditions, the CMC enzyme activity of strain ZJ-10 could reach 80.32 U/mL, which was 26.45% higher than that of the former optimization. In conclusion, strain of T. longibrachiatum ZJ-10 with strong CMC enzyme activity was screened in this study, which provides a good strain resource for the utilization of livestock, poultry and garden waste resources.

A method for simultaneous extraction, purification, and determination of persistent organic pollutants (POPs) in soil, such as polychlorinated biphenyls, polybrominated diphenyl ethers, and polycyclic aromatic hydrocarbons, was developed in this study. The optimum conditions for extraction and purification were as follows: Soil samples were extracted ultrasonically three times with acetone/n-hexane (1∶?1, by volume), followed by purification with Florisil solid-phase extraction column, and eluted by 12 mL of n-hexane/dichloromethane (9∶1, by volume) mixture solution. The eluant was concentrated by gentle N₂ streams and finally quantified by gas chromatography-mass spectrometry (GC-MS) with PCB209 as the internal standard. Except for 2, 2′, 3, 3′, 4, 4′, 5, 5′, 6, 6′-decabromodiphenyl ether (BDE209), the other 41 POPs were efficiently separated within 23.83 min. Excellent linearity was observed in the concentration range of 20-1 000 μg/L for all POPs with the coefficients of determination (R²) of 0.997 5-0.999 9. The detection limits of 42 POPs were 0.04-1.19 ng/g, and the spiked recoveries ranged from 71.04% to 120.89% with relative standard deviations of 0.88%-6.29%, and intra- and inter-day reproducibility variations were less than 11%. In conclusion, this method greatly reduces time and workload and is characterized by simple operation, good accuracy, and high sensitivity. It can be widely applied to the determination and analysis of POPs in soil, such as e-waste disposal site soil, which will facilitate further studies on the fate and risk assessment of POPs.

The identification and zoning of complex ecological functions is the research focus and application difficulty of territorial spatial planning, and it is also the ecological security guarantee for the green and sustainable development model. Taking Huzhou City of Zhejiang Province as the study area, we analyzed and evaluated the connotation and intensity of complex ecosystem services from the perspectives of ecological regulation, material production and landscape culture, and used a “three-dimensional Rubik’s cube” model to partition the space, and put forward control suggestions. The results were as follows: 1) The spatial agglomeration of ecosystem services in Huzhou City was significant. The high value area of ecological regulation service was concentrated in the central and western regions and the northern mountainous areas. The high value area of material production service was concentrated in the western water network plain areas. The high value area of landscape culture service was concentrated in the east-west axis regions and the northern mountainous areas. 2) According to the importance of ecological protection, the study area was divided into three levels and seven subareas based on ecological functions. The first level was the key ecological protection, including the core ecological protection zone and the important natural resource protection zone. The second level was ecological function guarantee, including general ecological protection zone, ecology-production economy compound zone and ecology-tourism economy compound zone. The third level was comprehensive utilization, including town-tourism economy zone and town-production economy zone. It is suggested that in the new era, the regional development should be considered as a bottom line for ecological protection and an upper limit for urban development. In the ecological protection space, we should actively explore the path to realize the value of ecological products, and give full play to the ecological function of natural resources in the rational layout of urban development space.

The positioning test was carried out in the Chongzhou Experimental Base of Sichuan Agricultural University in 2018—2019, aiming at exploring the effects of straw returning and nitrogen (N) fertilizer management on soil N supply and yield of direct seeding rice under the wheat (rape)-rice rotation. The two-factor split-zone design was adopted. The main area was wheat/rape straw being turned over to field (M₁) and straw being not returned to field (control, M₀). In the sub-area, on the basis of 150 kg/hm² of N application, there were three kinds of N fertilizer operation, including N fertilizer moving forward (N₁), balanced N application (N₂) and N fertilizer moving backward (N₃), with no N fertilizer application as a control (N₀). Then, the contents of soil ammonium-N, nitrate-N and total N, N accumulation and yield of direct seeding rice were determined. The results showed that the N accumulation of rice plant increased by 7.13% (8.50%) and the yield increased by 0.94% (1.43%) in 2018, and which increased to 15.17% (17.12%) and 6.60% (7.42%) in 2019 under the wheat (rape)-rice rotation at the maturing stage compared with those without straw returning. At the jointing stage in 2018, N accumulation amounts of direct seeding rice in the wheat (rape) stubble field were N₁＞N₂＞N₃ treatments as a whole. At the full heading stage and maturing stage, N accumulation amounts and yields of rice plants were N₃＞N₂＞N₁ treatments under the no straw returning, as well as N₂＞N₃＞N₁ treatments under the straw returning. Compared with the no straw returning, the ammonium-N contents in 0-10 and ＞10-20 cm soil layers at the rice maturing stage under the wheat (rape)-rice rotation increased or decreased after straw returning. While the nitrate-N contents decreased by 44.22% (30.99%) and 8.05% (20.09%) overall. Soil total N contents had little change in each growth stage of direct seeding rice, and the contents of nitrate-N, ammonium-N and total N in the soils under the N₁ treatment remained at a high level in each growth stage. In conclusion, continuous straw returning is beneficial to increase soil total N content; under the wheat (rape)-rice rotation, the balanced N application could effectively promote the N uptake by rice plants and significantly increase the rice yield, and the effect of increasing yield is better under the rape-rice rotation.

Pot experiments of lettuce in nine different typical types of soils, combined with multiple linear regression and static capacity model of soil environment, were conducted, and the effects of different ratios of substituting chemical nitrogen fertilizer by organic fertilizer on soil environmental quality, yield, and the safety of agricultural products and soil environmental capacity were studied. The results showed that partial substitution of chemical nitrogen fertilizer with organic fertilizer increased the total nitrogen and organic matter contents of the soil (except fluvio-marine yellow loamy soil), and significantly increased the yield of lettuce. The accumulations of heavy metals in different soil types and lettuce shoots under different fertilization treatments were significantly different. The application of organic fertilizer significantly increased the Cd contents in powdery-loamy paddy soil, silt-clayey yellow mettled paddy soil and hapl fluvo-aquic loamy soil. The contents of Cd, Cr, As, and Pb of lettuce planted in silt-clayey yellow mettled paddy soil, powdery-loamy paddy soil and hapl fluvo-aquic loamy soil all increased significantly after applying organic fertilizer, but decreased significantly in yellow-red soil. For the pot experiment with lettuce, the safety application ratios of organic fertilizer in hapl fluvo-aquic loamy soil, blue clayey paddy soil, silt-clayey yellow mettled paddy soil, powdery-loamy paddy soil, fluvio-marine yellow loamy soil, yellow-red soil and paddy field on desalting clayey polder were 10%, 20%, 30%, 10%, 30%, 20%, and 40%, respectively. The soil heavy metal environmental capacity decreased with the increase of application years of partial substitution of chemical nitrogen fertilizer with organic fertilizer, so it is important to strictly limit the application amount of organic fertilizer to protect the soil environment.

In the case of soil cadmium (Cd) pollution becoming more and more serious, the modified in-situ fixation method is widely used as one of the remediation methods of soil heavy metal pollution. To explore the remediation effects of mixed amendment M (the mass ratio of lime, zeolite, calcium-magnesia phosphate fertilizer and biochar was 71:23∶5∶1) on Cd-contaminated farmland soil, a two-year field experiment was conducted to study the effects of applying 0.1% (MR1), 0.2% (MR2), 0.5% (MR3) of the mixed amendment and 0.5% lime (LM) on the soil and crops, taking no application of the mixed amendment as a control (CK). The results showed that the mixed amendment reduced the bioavailability of Cd in soil mainly by increasing soil pH. Three kinds of addition of the mixed amendment (MR1, MR2, MR3) could maintain or increase the yield of crops and significantly reduce the content of Cd in rice straw and grain. Compared with the CK, the Cd content in rice straw treated by MR1, MR2, MR3 and LM decreased by 11.9%, 10.7%, 20.5% and 19.5%, respectively; and the Cd content in rice grains decreased by 42.9%, 57.1%, 71.4% and 72.1%, respectively. The Cd contents in rice grains under the all treatments were lower than 0.2 mg/kg, which met the food safety standard. Moreover, the mixed amendment could reduce the Cd uptake and transport capacity and grain bioaccumulation coefficient of rice. The results of phospholipid fatty acid analysis showed that the different application levels of mix amendment could increase the soil bacteria amount and the soil microbial community diversity. Compared with the LM, the number of bacteria in the MR2 treatment increased by 43.6%, and the number of Gram-positive bacteria in the MR3 treatment increased significantly to 56.5 nmol/g. In general, compared with the single application of lime, 0.2% of mixed amendment has few effects on soil physical and chemical properties, and increases the number and diversity of soil microbial communities, indicating that it can be used for the remediation of farmland soil Cd pollution while maintaining soil ecological health.

In order to comprehensively improve the soil quality of Chinese hickory (Carya cathayensis Sarg.) plantation and promote the sustainable and healthy development of hickory industry, a typical C. cathayensis plantation area (Lin’an District, Zhejiang Province) was selected for this study. Fractional vegetation cover, slope, soil fertility and soil pollution condition as evaluation indexes for soil degradation were considered. The spatial analysis of soil degradation degree for Chinese hickory plantation was carried out by fuzzy logic comprehensive evaluation method combined with geographic information system (GIS), global positioning system (GPS), and remote sensing (RS) technologies, and the corresponding management suggestions were put forward. The results showed that the soil fertility of plantation in the study area mainly belonged to the moderate degradation, and only 1.65% of the area was in a high degradation, which was centered in the north of Longgang Town and the southwest of Qingliangfeng Town. The overall soil pollution of the hickory plantation area was at a low level, only 6.35% of which was at a moderate to high degradation, mainly distributed in Daoshi and Tuankou towns. The comprehensive soil degradation of the hickory plantation mainly belonged to moderate and low degradation degrees, accounting for 66.50% of the study area. The high, moderate to high, moderate and low degradation areas accounted for 0.15%, 2.44%, 27.45% and 3.46% of the study area, respectively. The highly degraded hickory plantation was mainly distributed in the southwest of Qingliangfeng Town and the west of Longgang Town. The results will provide a theoretical basis for improving soil quality and the sustainable development of hickory property.

In order to explore the migration and enrichment law of uranium (U) and its related elements in farmland soils (aeolian sandy soils) and plants in Qianjiadian U mining area of Inner Mongolia, the roots, stems, leaves and rhizosphere soil samples of zoysiagrass, sorghum, peanut, corn, willow and poplar were collected systematically. The contents of 13 kinds of heavy metal elements such as uranium (U), arsenic (As), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), molybdenum (Mo), nickel (Ni), lead (Pb), antimony (Sb), thorium (Th) and zinc (Zn) were analyzed, as well as their bioconcentration factors and translocation factors among the soils and plants. The results showed that: 1) The content of heavy metal elements in the aeolian sandy soil of Qianjiadian U mining area was low, and the concentration coefficient was mostly lower than one. Uranium was significantly positive correlation with other elements. 2) The contents of heavy metal elements in the zoysiagrass and its rhizosphere soil were higher than those of other plants. 3) The plants had selective absorption of heavy metal elements, among which poplar had the strongest enrichment effect on Cd, while zoysiagrass, peanut and willow could enrich Cu, Mo and Zn, respectively. 4) The absorption of heavy metal elements by various organs was generally in the order of leaf＞root＞stem. On the whole, the content of heavy metal elements in the aeolian sandy soil is low, and the plants have strong selective absorption capacities of Cd and Zn in soil, and strong tolerance to heavy metal elements. Zoysiagrass, sorghum and peanut can be used as candidate plants for ecological restoration after mining.

Islands have special geographical landscapes and complex soil forming conditions, where the soil formation is different from that in mainland areas. To understand the genesis characteristics and taxonomic classification of island hilly soils in Zhejiang Province, 80 soil profiles were surveyed combining with historical literature data in this study. The results showed that the geomorphic structures, parent materials, climatic conditions, and vegetation types of the soils were relatively single, but the soils were frequently affected by the island scales, distances from land, tide, and human activities. The terrain slope was large; the lithification was obvious; the clayization was weak; the desilicification-allitization was changeable; the weathering-leaching coefficient was medium; the restoring base cations were obvious; the pH value and base saturation percentage were higher than those in the mainland at the same latitude; and the soil forming environment was affected by both ancient and modern factors. Four soil orders, namely Ferrosols, Argosols, Cambosols, and Primosols, were identified from the islands of Zhejiang Province, including 7 suborders of Ustic Ferrosols, Udic Ferrosols, Ustic Argosols, Udic Argosols, Ustic Cambosols, Udic Cambosols, and Orthic Primosols, as well as 10 soil groups, 11 subgroups and 25 soil families. In conclusion, the direction of soil formation from the islands of Zhejiang Province is basically the same as that of mainland hilly soil at the same latitude, belonging to the traditional ‘red soil zone’.

In this research, we surveyed the habitat factors in different regions in the core area of Changxing Chinese Alligator (Alligator sinensis) Nature Reserve of Zhejiang Provinceand their effects on the egg laying of the female alligators during the breeding season. The results revealed that the female alligators preferred to build nests on the regions covered with dense bamboo groves or tall trees. Few nests were found on the regions dominated by weeds and with few tall dominant trees. Investigation on the habitat factors in different regions showed that the dry mass of litter per unit surface area, the height of dominant species and the surface slope were the three major factors that affected the female alligators to choose the site for nesting. The above results could provide references for the habitat optimal transformation, and for the novel habitat selection. Our results could also facilitate the development of conservation programs for Chinese alligator.

Using a three-factor two-level randomized block design, the ‘Sumai 188’ variety was taken as the field experimental material to set up two levels of fertilization, i.e., conventional fertilization and reducing 20% of fertilizer, two levels of applying silicon fertilizer, i.e., within Si-Ca-K-Mg fertilizer (150 kg/hm² Si, Si₁) and without Si-Ca-K-Mg fertilizer (Si₀), together with two levels of applying pesticides, i.e., within applying pesticides and without applying pesticides. There were eight treatments for 24 plots in total with three replicates. The effects of applying Si fertilizer combined with reducing fertilizers and pesticides on wheat yield, quality, and resistance to wheat scab were studied. The results showed that, as compared with other treatments, applying Si combined with reducing fertilizers and pesticides increased stem wall thickness of wheat by 29.6%-36.5%, and applying Si combined with fertilizers and reducing pesticides significantly increased wheat yield by 9.4%-47.0%. Compared with the treatment of Si₀, the increased wheat yield was noted by 7.3%-21.4%, and the increased wheat lodging resistant index by 12.6%-37.6% in the treatment of Si₁, respectively. The incidence of wheat scab was 16.5% by applying Si combined with reducing fertilizers and pesticides. Therefore, applying Si combined with reducing fertilizers and pesticides can effectively increase the stem wall thickness and wheat yield, improve the lodging resistance of wheat, significantly reduce the incidence of wheat scab. The application of Si-Ca-K-Mg fertilizer has positive significance for reducing the dosage of fertilizer and pesticide.

By using a ¹³C natural abundance method, this study investigated the rhizosphere priming effects (RPE) of sorghum and maize growing in two types of soil (paddy soil and lou soil) at two stages, and the contents of light fraction organic carbon (ρ₁＜1.7 g/cm³) and heavy fraction organic carbon (ρ₂＞1.7 g/cm³) of soil were also determined. The results showed that planting crops significantly enhanced the soil organic matter decomposition. And the maize induced the most CO₂-C flux derived from soil organic carbon at the trumpet stage in paddy soil, which reaching 18.49 mg/(kg?d). The maize induced stronger RPE than sorghum across all growth stages, which indicated that planting maize would bring more CO₂ emission. The content of light fraction organic carbon of soil changed significantly, while the content of heavy fraction organic carbon remained stable during RPE process. Hence, RPE may directly function on the light fraction organic carbon. This study provides the theoretical basis for controlling the RPE intensity reasonably and reducing global CO₂ fluxes.

Under the iron-deficiency condition, roots of graminaceous plants secrete mugineic acids into the soil. To determine the effects of rice root exudate 2\mathrm{\prime }-deoxymugineic acid (DMA) on rhizosphere and root endosphere bacterial community, wild type rice named as Nipponbare and osbhlh156 and iro2 mutant rices that loss the ability to secrete DMA were used as experimental materials in this study. The rhizosphere and root endosphere microorganisms were sampled for DNA extraction and 16S rRNA gene amplicon sequencing and data analysis. The results showed that soil types and cultivation conditions had significant impacts on rhizosphere and root endosphere bacterial community composition. In contrast, the root exudate DMA had relatively less impact, but not negligible. The bacterial species and diversity decreased from rhizosphere to root endosphere, which confirmed that the root endosphere bacteria were gradually selected and colonized inside root by interacting with plants. Nine microbial taxa, including Bradyrhizobium and Dictyobacter, etc., were selected as biomarkers, to distinguish whether there is DMA secretion in the rice rhizosphere. Through functional prediction, it was found that the bacterial taxa with adenosine triphosphate-binding cassette (ABC) transporter function may be involved in plant iron transport and related function. This study clarifies the effects of DMA on the composition of rhizosphere and root endosphere bacterial community of rice and provides data support for the comprehensive analysis of the role of microorganisms in response to iron deficiency in rice.

Mulberry sclerotial disease is a devastating disease in mulberry production. In order to understand the existent situation of pathogens and their microecology in the soil of the mulberry field, we collected the soil samples from mulberry fields in four plots of different regions in Zhejiang Province [namely Deqing County (DQ), Changxing County (CX), Jinhua Duohu Residential District (JD) and Jiangdong Town (JJ)]. Among them, CX mulberries were cultivated in greenhouse, and the others were cultivated in open field. The experiment took one plot in Sichuan Province as a control (CK), which was rarely or never found the sclerotial disease. Then, we identified the soil fungi and bacteria through high-throughput sequencing of internal transcribed spacer (ITS) and 16S rRNA. The results showed that the relative abundance (RA) of genus Ciboria in the mulberry fields of DQ, JJ and JD were 28.84%, 60.17%, and 70.15%, respectively. No diseased fruit of mulberry sclerotinia was found in CX and CK fields, and the relative abundance of Ciboria was 0.02% and 0.06?, respectively. The main microorganisms in CX field were Mortierella, Chaetomium, and Humicola, with the relative abundance of 36.46%, 21.59%, and 15.93%, respectively; the main microorganisms in CK field were Penicillium, Fusarium, and Fusicolla, and their relative abundances were 24.05%, 15.35%, and 9.75%, respectively. Among the bacteria, Pseudomonas was the only genus identified in all five field samples, and the highest relative abundance of Pseudomonas was found in the JJ field (but only 6.81%), highlighting a rich bacterial diversity. Collectively, the relative abundance of the genus Ciboria and the diversity of fungi and bacteria reveal the complex relationship between the relative abundance of Ciboria and the soil microecology in mulberry fields. It also further implies the possibility of preventing and controlling mulberry sclerotial disease by changing the soil microecological structure.

To understand the spatial variability and influencing factors of soil properties developed from parent materials of red bed, taking Zhejiang Province as an example, the distribution, formation features and genetic characteristics of soils developed from parent materials of red bed in the subtropical region were examined, and the effects of paleoenvironment of red bed formation, modern topography and land-use mode on the physical and chemical properties of the soils were analyzed, and the classification of the soils was discussed. The results showed that the distribution of soils developed from parent materials of red bed was determined by the geological structure. The formation of the soils on red bed was a result of balance between physical weathering and surface erosion, while chemical weathering and decalcification led to soil acidification. The soils developed from parent materials of red bed tended to be juvenile, which was the common result of the special weathering characteristics of the parent material and the short soil forming time. The paleoenvironment of red bed formation had a profound impact on the material composition of the soils, and the modern topography affected the stage of soil development, and the land-use mode could change the vertical development of the soils. The color of soils developed from parent materials of red bed was not generally believed to always retain the color of the parent materials. In some cases, the former was different from the latter. Due to the complexity of red bed genesis and the diversity of material composition, the soils developed from parent materials of red bed were far more complex and changeable than generally believed. According to the “Chinese soil classification system”, the soils developed from parent materials of red bed in Zhejiang Province were only classified as purple soil group, and divided into calcareous purple soil and acid purple soil subgroups, which could not well reflect the changeable characteristics of soils developed from parent materials of red bed. According to the diagnostic horizons and diagnostic characteristics of “Chinese soil taxonomy”, the soils developed from parent materials of red bed in Zhejiang Province could be divided into two soil orders (Cambosols and Primosols), two suborders (Udic Cambosols and Orthic Primosols), seven soil groups and fourteen subgroups.

To study the degradation of hexachlorobenzene (HCB) in contaminated soil by dielectric barrier discharge (DBD), a fluidized-bed DBD reactor was used to degrade HCB in contaminated soil. The results showed that a discharge current pulse could be generated with a 20 μs pulse width. When the air flow rate was 4.0 L/min, the soil reached a fully fluidized state. The energy density of reactor increased with the increase of discharge voltage, which promoted HCB degradation, but increasing heating led to lower energy utilization. The HCB degradation rate reached 97.3% after 32 min while the energy density was 172.5 J/L at a discharge voltage of 16 kV. The neutral or alkaline condition was more beneficial to HCB degradation than the acidic condition. With the increase in the initial HCB concentration, the degradation rate of HCB decreased, but the absolute degradation amount increased. The degradation of HCB conformed to first-order kinetic equation. During the discharge process, the C—Cl bond was attacked by active substances, and low-substituted chlorobenzene and small molecular organic acids and other byproducts were generated, which indicated that the degradation of HCB in contaminated soil was mainly a dechlorination process. The research results have important practical significance for the remediation of actual contaminated soil.

Polychlorinated biphenyls (PCBs) are typical pollutants in soil. Nanoscale zero-valent iron (nZVI) can effectively dechlorinate high-chlorinated PCBs into low-chlorinated PCBs which can be more easily degraded by microorganisms. In this study, soil samples contaminated by PCBs were collected from an e-waste recycling site in Taizhou, Zhejiang Province. The remediation of combined nZVI and PCBs-degrading strain Rhodococcus pyridinovorans R04 was carried out to investigate the removal effect of PCBs in soil. The results showed that the combined treatment of nZVI and degrading strain R04 had better effects than the treatment of nZVI or R04 alone in removing PCBs or various chlorinated PCB congeners in soil. After combined treatment with nZVI and degrading strain R04 for 32 d, the removal rate of PCBs in soil reached 59.4%, which was higher than 46.1% of nZVI treatment and 34.4% of degrading strain R04 treatment (P＜0.05). Therefore, the combination of nZVI and degrading bacteria in the remediation of PCBs contaminated soil has good application potential.

To explore the effects of seabuckthorn fruit residue on soil physicochemical properties, greenhouse gas (CO₂, CH₄, N₂O) emissions, and the microbial numbers, a 28-day soil pot experiment was conducted. Three groups of materials were used, including seabuckthorn fruit residue (R), biochar (B), and biological ceramsite (T) in the experiment, and a natural culture was used as the control group (CK). The results showed that the seabuckthorn fruit residue significantly promoted the contents of soil nutrients such as total carbon, total nitrogen, and available potassium, and the average increase rates were 16.31%, 14.99%, and 46.15%, respectively. Besides, the soil pH was also enhanced from 0.25 to 0.69. The microbial numbers in the soils treated with seabuckthorn fruit residue were promoted significantly. The average growth rate of microorganisms in the first 14 days was 335.6% higher than that of the control. The CO₂ emissions and global warming potential (GWP) with the treatment of seabuckthorn fruit residue were higher of biochar (R) treatment, while the CH₄ and N₂O emissions were both lower than those of biochar (B) and biological ceramsite (T) treatments. In general, the seabuckthorn fruit residue showed relatively high returning value, but its risk of greenhouse gas emission should also be considered. This study can provide some references for the practice of returning seabuckthorn fruit residue into the field.

To evaluate phytotoxicity of zinc oxide nanoparticles (ZnO NPs) on plants, the effects of 0, 5, 50, 250 mg/L ZnO NPs on nutrient uptake and photosynthesis of lettuce were studied using hydroponic culture with Zn²⁺ and^{bulk ZnO as comparisons. The results showed that ZnO NPs inhibited the growth of lettuce, and biomass of lettuce decreased obviously with the increase of ZnO NPs concentration. Under the 5-250 mg/L ZnO NPs treatments, the contents of magnesium (Mg), iron (Fe), manganese (Mn) and copper (Cu) in the shoots of lettuce were reduced by 18.0%-33.3%, 19.0%-28.6%, 17.2%-28.3% and 17.4%-33.8%, respectively. Further-more, 50 and 250 mg/L ZnO NPs treatments significantly decreased the chlorophyll content and chloroplast activity of lettuce. Under the 5-250 mg/L ZnO NPs treatments, net photosynthetic rate (P_n), stomatal conductance (G_s), intercellular carbon dioxide concentration (C_i) and transpiration rate (T_r) of lettuce decreased by 33.7%-75.0%, 21.3%-36.7%, 11.2%-29.0% and 30.7%-83.4%, respectively; the maximum photochemical efficiency (F_v /F_m), photochemical quenching coefficient (qP), actual photochemical quantum yield (Φ_PSⅡ), and electron transport rate decreased by 6.3%-18.8%, 7.0%-14.0%, 5.0%-20.0% and 5.8%-20.7%, respectively. The inhibition of 250 mg/L ZnO NPs on the photosynthesis of lettuce was much greater than that of the corresponding Zn2+ release amount and bulk ZnO with the same concentration. These results indicate that ZnO NPs can inhibit the photosynthesis of lettuce by affecting the mineral nutrient absorption, hindering the chlorophyll synthesis, and reducing the photosystem Ⅱ activity.}

A field experiment was carried out on ‘Zheyou 21’ rice cultivar, and the effects of topdressing of silicon (Si) fertilizer on stress resistance and yield of rice were studied at two levels of pesticide application. The normal level of pesticide application (375 g/hm² 75% tricyclazole wettable powder, D1) and the reduced level of pesticide application (225 g/hm² 75% tricyclazole wettable powder, D2) were set up. Each level of pesticide application contained two Si fertilizer treatments, including non-topdressing of Si fertilizer (－Si) and topdressing of Si powder fertilizer (750 kg/hm², ＋Si). The results showed that compared with －Si, the ＋Si increased the breaking resistance of the second stem by 26.71%, and reduced the lodging index by 13.29%, incidence of rice ear neck blast by 15.37%, disease index by 19.09%, and increased yield by 3.33% (P＜0.05) of rice under the treatment of D1. Compared with －Si, the ＋Si increased the breaking resistance of the second stem by 33.67%, and reduced lodging index by 14.04%, incidence of rice ear neck blast by 28.98%, disease index by 23.11%, and increased yield by 11.44% (P＜0.05) of rice under the treatment of D2. In conclusion, topdressing of Si fertilizer could reduce lodging index and disease index of rice ear neck blast, leading to enhance lodging resistance and disease resistance to rice ear neck blast, and increase rice yield under the reduced level of pesticide application. In the case of no Si topdressing, rice yield was reduced due to the reduction in pesticide application, while in the case of Si topdressing, there is no significant effect on rice yield.

In order to explore the nutrient content, return rate and stoichiometric characteristics of plant leaf-litter-soil in alpine forest, the typical forests of Sejila Mountain in Southeast Tibet were analyzed. The results showed that for the same forest type, the contents of organic carbon (C), total nitrogen (N), total phosphorus (P) and total potassium (K) in 0-10 cm soil layer were the highest, while those in ＞20-30 cm soil layer were the lowest. The contents of total N, total P and total K in the samples were new leaf＞old leaf＞litter＞soil, while the content of organic C was old leaf＞new leaf＞litter＞soil. The stoichiometric ratios of C to N, C to P, and C to K of soil, litter, new and old leaves, respectively, were coniferous forest＞broad-leaved forest. It could be seen that coniferous forest was more conducive to the accumulation of C, and broad-leaved forest was conducive to the accumulation of mineral nutrients of N, P, and K. The stoichiometric ratios of N to P in plant leaves ranged from 2.87-5.27, which were significantly lower than the global average level (16.00). It was indicated that this study area was obviously restricted by N element. The nutrient return rates of N, P, and K were all positive, and generally showed that the broad-leaved forest was higher than the coniferous forest. The results provide data support for scientifically clarifying the plant leaf-litter-soil nutrient cycle of forest ecosystem in Southeast Tibet.

Spatio-temporal variation characteristics of soil pH, soil organic matter, total nitrogen, available phosphorus and available potassium contents were determined in Wenling City of Zhejiang Province in 2006 and 2017, respectively, using the analysis methods of mathematical statistics and inverse distance weighting spatial interpolation. The results showed that the soils presented a certain acidification trend with a decrease in soil pH of 5.40%. Soil organic matter (SOM) and nitrogen, phosphorus and potassium contents showed an overall increasing trend. Available phosphorus and available potassium contents increased significantly, with increased ratios of 50.34% and 26.23%, respectively. SOM and total nitrogen contents also increased to a certain extent, increasing by 13.97% and 10.76%, respectively. The results of spatial analysis showed that the soil pH decreased in the west of Wenling, while increased in the east of Wenling. Total nitrogen contents of the soils decreased in the north of Wenling, while increased in the south of Wenling. The available phosphorus and available potassium contents increased significantly. The above results indicate that fertilizer application will be implemented according to soil pH, the abundance and deficiency of nitrogen, phosphorus and potassium, and the law of fertilizer requirements for crops. The improvement of the soil quality and soil sustainable development will be focused on.

In order to study the spatial distribution characteristics and sources of heavy metal contents in the soil of main wine-making vineyards in Jiayuguan City, Gansu Province, and to evaluate the levels of heavy metal pollution and potential ecological risk, we combined geographic information system-based spatial analysis with multivariate statistical analysis to determine the contents of eight heavy metal elements in the soil, including copper (Cu), zinc (Zn), chromium (Cr), nickel (Ni), lead (Pb), arsenic (As), cadmium (Cd), and mercury (Hg). The results showed that there were obvious heterogeneity in the spatial distribution of the above elements, and the Cr had a slight accumulation behavior. According to the analysis of the spatial distribution characteristics of metal elements, it was found that the content of each element (except Cd) presented a certain spatial distribution law. The high content areas were mainly located in the Jiayuguan Industrial Zone and the northeast of Jiuquan Iron and Steel Group, as well as near Xiazhuang, Henggou and Renjia villages in the southwest. Through pollution source analysis, we thought preliminarily that the sources of Cu, As, Ni, Pb, Zn, and Hg elements may be affected by the soil parent material factors, and Cr was related to the effects of industrial sources and agricultural activity sources dominated by the iron and steel industry. By further analysis of the individual coefficient of potential ecological risk and the comprehensive index of potential ecological risk, it was found that the eight heavy metal elements all arose slight ecological risks in the research area, Cd and Hg of which were the main ecological risk factors for the local wine-making vineyard. Therefore, in the future cultivation process, we should trace the source, strengthen the prevention, control and treatment of excessive heavy metal pollution, and cultivate rationally to improve the soil environmental quality of the local wine-making vineyard, thereby ensuring the safety and quality of viniferous grapes and wine.

Atrazine (ATZ) is one of the most popular herbicides, and the pollution of atrazine to surface water and groundwater has aroused people’s concern, which is urgent to research and develop water purification technology to deal with it. Boron-doped diamond (BDD) electrode has the advantage of highly efficient production of ·OH, but the degradation of organic pollutant is seriously limited because the ·OH is trapped on the surface of the electrode. In this study, BDD electrode modified by polytetrafluoroethylene (PTFE) improved the degradation efficiency of ATZ. In NaCl solution, after modification with 5.0%, 8.6% and 20.0% PTFE dispersions, the quasi-first order kinetic constants of ATZ degradation reaction were improved by 98.9%, 88.2% and 78.6%, respectively. In NaHCO₃ and Na₂SO₄ solutions, after modification with 8.6% PTFE dispersion, the quasi-first order kinetic constants of ATZ degradation reaction were improved by 49.2% and 127.0%. The PTFE was coated on the surface of BDD electrode in the form of film, which was beneficial to the improvement of the current. Meanwhile, the bubbles that adhered to the surface of BDD were conducive to the formation of ·OH and diffusion of ·OH into the homogeneous solution. The concentration of ·OH in the solution bulk increased by 17.73, 19.89 and 18.81 times after the modification of 5.0%, 8.6% and 20.0 % PTFEs, respectively, and the degradation efficiency of ATZ and removal effect were significantly enhanced. The main ways of ATZ degradation by PTFE modified BDD electrode were dealkylation, dechlorination-hydroxylation and alkyl oxidation reactions.

This paper studied the effects of different seedling quality traits of Sedum plumbizincicola on the removal rate of cadmium (Cd). By the methods of correlation analysis, principal component analysis and clustering analysis, it was found that seedling quality had a great impact on Cd removal efficiency and remediation cost, and stem diameter, branch number, seedling height and Cd content were the important indexes to determine the quality of seedlings. The shoot Cd uptake of the Ⅰ or Ⅱ grade seedling with stem diameter≥5.0 mm, branch number per plant≥2, seedling height≥6.0 cm and seedling Cd content≤5 mg/kg, was more than 200 g/hm² after 90 d of planting. The remediation efficiencies of the Ⅰ and Ⅱ grade seedlings were over 3.4 times higher than the Ⅳ grade seedling (stem diameter＜4.0 mm, branch number per plant of 0-1, seedling height＜6.0 cm, seedling Cd content≤5 mg/kg), and using Ⅰ and Ⅱ grade seedlings could effectively save labor cost, and reduce or avoid herbicide application. A case of large-area heavy metal contaminated soil remediation was carried out to test this quality classification standard for S. plumbizincicola seedlings, and it was found that the shoot Cd uptake of the Ⅰ or Ⅱ grade seedling was 222.35 g/hm² after 120 d of planting, and the remediation effect could reach or even higher than that of 6-8 months in previous experiments. In summary, the high-quality S. plumbizincicola seedlings is an important basis for improving remediation efficiency and reducing remediation cost. This study clarifies the quality traits and remediation efficiencies of different grades of seedlings. This standard for grading S. plumbizincicola seedlings is helpful to promote the standardization and mechanization of remediating heavy metal contaminated soil with this plant.

The high degree of intensive utilization of vegetable field soils is prone to nutrient imbalance and excessive accumulation, which hinders the sustainable development of vegetable production. Based on the analysis of fertility status and main obstacle factors of vegetable field soils under the open land and facility cultivation patterns in the Xitiaoxi watershed, the threshold of soil phosphorus (P) loss was explored in this study. The results indicated that the soil pH value under the open land cultivation pattern was significantly lower (P＜0.05) than that under the facility cultivation pattern. The contents of soil total potassium (K), available K, available P, and water-extractable P under the facility cultivation pattern were significantly higher (P＜0.05) than those under the open land cultivation pattern, as well as the total soluble salt content and electrical conductivity. It was also found that the fertility grades of vegetable field soils under the two cultivation patterns were mostly (95.8%) Grade Ⅱ. The correlation between soil water-extractable P and Mehlich 3-P was well illustrated with the piecewise linear regression equation. The threshold of Mehlich 3-P for controlling P loss from the open land and facility vegetable field soils was estimated to be 102.7 mg/kg and 128.7 mg/kg, respectively. Thus, the soil samples exceeding this threshold accounted for 65.0% and 83.3% of the total number of samples, respectively. In conclusion, the soil acidification and the risk of P loss under the open land and facility cultivation patterns in the Xitiaoxi watershed are serious, and the soil salinization under the facility cultivation pattern is an outstanding issue.

By selecting a typical blue clayey paddy soil with planting single-season rice in the southeast coast, we studied the effects of urea fertilizer containing N-(n-butyl) thiophosphoric triamide (NBPT, urease inhibitor) and 3, 4-dimethylpyrazole phosphate (DMPP, nitrification inhibitors) biochemical inhibitors on the nitrogen transformation in the surface water and soil and rice growth under the different fertilization times and levels. The results showed that: compared with the conventional urea fertilizer treatment, when the urea added with NBPT and DMPP combined biochemical inhibitors was applied twice as 50% base fertilizer and 50% topdressing, the concentrations of ammonium, nitrate and nitrite in field surface water decreased by 7.0% and 13.2%, 46.5% and 50.5%, 75.4% and 58.2% at the regreening stage and early tillering stage of rice, respectively; the ammonium concentration in soil decreased by 21.8% at the regreening stage and increased by 27.5% and 9.3% at the later tillering stage and jointing stage of rice; besides, the plant height, tiller number and chlorophyll content of rice were increased by 4.8% and 4.1%, 4.9% and 11.8%, 17.8% and 15.9% at the tillering stage and jointing stage, respectively. Furthermore, the yield and biomass of rice increased by 6.8% and 12.5%, 9.2% and 12.6%, respectively, at the mature stage, when the urea added with NBPT and DMPP combined biochemical inhibitors was applied once as base fertilizer or twice as 50% base fertilizer and 50% topdressing. In conclusion, the combined application of NBPT and DMPP biochemical inhibitors can effectively inhibit the rapid increase of ammonium and nitrate nitrogen in soil and field surface water, delay the transformation rate of nitrogen form, and maintain the relatively low nitrate nitrogen concentration in the surface water and soil in the rice fields, which can reduce the risk of nitrogen loss in paddy fields, promote rice growth and increase rice yield.

Based on the experimented cadmium (Cd)-contaminated vegetable fields, the effects of slow release fertilizers (coated with sulfur, phosphate and attapulgite) on soil nitrogen loss and Cd contents were studied. The results showed that, compared with the conventional fertilizer treatment, the contents of \mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{－}-N and dissolved nitrogen (DN) were improved by 5.6%-22.2% and 29.6%-50.6% in the soil samples, and the contents of \mathrm{N}{\mathrm{O}}_{\mathrm{3}}^{－}-N and DN in the leaching solution were decreased by 9.4%-17.4% and 22.8%-31.8%, respectively, indicating that slow release fertilizers could relieve nitrogen loss in soil. The soil electrical conductivity, available phosphorus and available potassium contents increased by 33.5%-41.6%, 63.1%-100.0% and 27.3%-42.7%, respectively. The contents of soil total Cd and available Cd were decreased by 13.5%-16.4% and 37.6%-48.0%, respectively, compared with those of the initial soil. The above results suggest that the coated slow release fertilizers can realize the safe utilization of mildly and moderately Cd contaminated vegetable fields. It provides a theoretical basis for the scientific application of slow release fertilizers to reduce non-point source pollution and heavy metal contamination in a vegetable field.

Rhizosphere microorganisms play an important role in plant growth and adaptation to the environment. In order to reveal the characteristics of rhizosphere bacterial community of endangered plant Cupressus gigantea in Tibet, we employed 16S rRNA gene high-throughput amplicon sequencing technology combined with soil chemical properties to examine the rhizosphere bacterial composition and diversity in Bayi District, Milin County, and Langxian County of Nyingchi City in Tibet and their influencing factors. The results showed that the diversity of bacteria in the rhizosphere of C. gigantea was rich, and the dominant bacterial phylum were Actinobacteriota, Proteobacteria, and Acidobacteriota. There were 757 shared genera (65.83%) of rhizosphere bacteria in C. gigantea in Langxian County, Bayi District, and Milin County, with 125 (10.87%), 39 (3.39%) and 41 (3.56%) unique genera, respectively, and the β-diversity analysis of non-metric multidimensional scaling based on Bray-Curtis distance revealed significant differences among populations. The positive correlation of the co-occurrence network of bacterial communities was more than 68%, and the cooperative relationship was greater than the competitive relationship. Soil available phosphorus (AP), total phosphorus (TP), and ammonium nitrogen (NH₄⁺-N) were important factors driving changes in the structure of rhizosphere bacterial community. In order to adapt to different growth environments, various groups of C. gigantea have formed unique rhizosphere bacterial communities. The above results can provide a reference for studying the role of rhizosphere microorganisms in the growth and environmental adaptation of C. gigantea and the protection of C. gigantea resources.