Effects of biochar application on nitrogen transformation and N2O emission in a coastal saline-alkali soil.

The application of biochar can improve soil fertility and benefit sustainable agricultural development and carbon neutrality simultaneously. To better understand the effects of biochar addition on nitrogen transformation and N2O emission in a coastal saline-alkali soil and its potential mechanisms, we conducted a 60-day laboratory incubation experiment with six treatments, i.e., ammonium sulfate (N 150 mg·kg-1), ammonium sulfate + 0.4% (weight/weight) biochar, ammonium sulfate + 0.6% biochar, ammonium sulfate + 0.8% biochar, ammonium sulfate + 1.6% biochar, and ammonium sulfate + 0.2% biochar and 0.2% organic fertilizer (based on equivalent N basis). The results showed that soil nitrogen transformation was mainly affected by biochar addition at the early stage of incubation. Biochar addition significantly increased the contents of nitrate and ammonium. Biochar addition significantly increased soil net nitrification rate, but the magnitude of such increases decreased with increasing biochar addition level. Similar temporal change patterns of N2O emissions were observed in all treatments, and the N2O emissions mainly occurred in the first 30 days of incubation. Compared with the CK, biochar addition significantly reduced the cumulative N2O emission, and the decrement increased with increasing biochar addition levels. In conclusion, the effects of biochar and nitrogen fertilizer addition on soil nitrogen transformation and N2O emission varied with the application rate. Biochar addition with a rate of 0.8% (W/W) increased soil inorganic nitrogen content and decreased soil N2O emission. It could provide theoretical basis and reference for the formulation of reasonable plans for the improvement and utilization of biochar in coastal saline-alkali soil.

[Spatial Distribution of Aerobic Bacteria, Sources and Risks of Nitrogen and Phosphorus in Taihu Lake Sediments].

The release of nitrogen and phosphorus from sediments into lake water will exacerbate the eutrophication of lakes and endanger ecological safety and human health. Microorganisms are indispensable in nitrogen and phosphorus conversion, and accurate analysis of the distribution characteristics and sources of nitrogen and phosphorus in sediments as well as their relationship with microorganisms is an important prerequisite for lake eutrophication control. Taking Taihu Lake as the study area, 30 surface sediment samples were collected, and the grain size, pH, organic matter (OM), dissolved organic carbon (DOC), total phosphorus (TP), total nitrogen (TN), nitrate nitrogen (NO3--N), and dissolved organic nitrogen (DON) along with some other index contents were measured and analyzed; accordingly, spatial distribution characteristics were analyzed. While using nutrient agar (NA), the number of aerobic bacteria (AB) was determined by plate counting in the medium. Combined with principal component analysis (PCA) and Pearson correlation analysis, the spatial distribution characteristics and sources of sediments and AB in Taihu Lake were explored. The characteristics of sediment pollution in Taihu Lake were studied using the comprehensive pollution index and the organic pollution index methods. The results revealed that the average sediment indicators of the surface layer of Taihu Lake were as follows:AB was 9.25×104 CFU·g-1, average particle size (MZ) was 17.59 µm, pH was 7.62, ω(OM) was 15.05 g·kg-1, ω(DOC) was 71.60 mg·kg-1, ω(TP) was 598.13 mg·kg-1, ω(TN) was 1113.92 mg·kg-1, ω(NO3--N) was 3.22 mg·kg-1, and ω(DON) was 22.60 mg·kg-1. The comprehensive pollution index (FF) showed that 13% of the Taihu Lake was moderately polluted, while 87% was heavily polluted. Excluding the area in the center of the lake, the southern lake area, and some lakes in the western part of the East Taihu Lake, TN in the rest of the area was moderately and severely polluted. In addition to the heavy pollution of Zhushan Bay, the TP in Taihu Lake was generally at light and moderate pollution. The organic pollution index (OI) showed that the organic pollution of the sediments of Taihu Lake was relatively light, majorly caused by organic nitrogen (ON) pollution. DOC, DON, TN, and OM in Taihu Lake were primarily derived from the influence of aquatic plants, and TP And AB were primarily derived from the influence of the external input of rivers. This research will provide theoretical support for lake eutrophication treatment and also provide new ideas for further analysis of AB to remove nitrogen and phosphorus pollution from sediments.

A combined method for human health risk area identification of heavy metals in urban environments.

Multi-medium heavy metals pollution is a crucial pathway to destroy the urban environmental resources cycle. In this study, Nanjing of China, a typical mega city, was taken as the study area. Compared with other cities or countries, Cr, Cu and Zn in human nails and hair in the study area have higher concentration characteristics, while Cd and Pb have lower concentration characteristics. By combining the health risk status of heavy metals in soil and dustfall, the spatial clustering characteristics of heavy metals in soil dustfall and the concentration information of heavy metals in humans in the study area, a potential toxic risk area identification method based on soil-dustfall-human (SDB-HR) was established. Through Monte Carlo analysis, it's found that the risk of Zn and Cr in soil-dustfall to human health is relatively high, with the probability of carcinogenesis reaching 51.2 % and 50.2 %, respectively. By the proposed method, different levels of heavy metal risk areas in urban environments can be more reasonably and effectively identified, which will provide important technical and theoretical support for the precise management of heavy metals in urban environments.

Source-oriented ecological risk assessment of heavy metals in sediments of West Taihu Lake, China.

The geographical location of West Taihu Lake determines that it is the entrance of the whole Taihu Lake, and the intensive industries around it pose a great threat to the ecology of Taihu Lake. We innovatively combined Pb isotope ratio analysis with ecological risk assessment index to quantify the source-oriented ecological risk of heavy metals (HMs) in the sediments of West Taihu Lake. In this study, the representative HMs Zn, Pb, Cr, and Cd in the surface (0-2 cm) sediments of West Tai Lake were determined, and the ecological risk assessment of HM sources was carried out based on the Pb isotope ratio and ecological risk index. The results showed that HMs were significantly enriched in the south and the west of the study area. The average geo-accumulation index (Igeo) of Pb was unpolluted, Cr and Zn were between unpolluted and moderately polluted, and Cd was moderately polluted. The average ecological risk index (Ei) of Pb, Cr, and Zn was low, and only Cd reached a considerable risk (ECd = 120.7), which accounted for 89.8% of the comprehensive ecological risk index (RI). However, the RI in the whole study area (RI = 134.4) still indicated low risk. There was a significant correlation between Pb and other HMs (P < 0.05). The IsoSource analysis showed that the order of contribution rate was fossil fuels (48.0%) > industrial sources (35.8%) > natural sources (14.9%) > agricultural sources (1.3%). The HM pollution caused by fossil fuel combustion and industrial activities reaches a moderate ecological risk, whereas natural sources and agricultural sources pose a low risk. Overall, the main sources of HM pollution are anthropogenic, which pose moderate ecological risk to the study area and should be paid more attention to.

Developmental and Reproductive Impacts of Four Bisphenols in Daphnia magna.

Bisphenol A (BPA) is a typical endocrine-disrupting chemical (EDC) used worldwide. Considering its adverse effects, BPA has been banned or strictly restricted in some nations, and many analogs have been introduced to the market. In this study, we selected three representative substitutes, BPS, BPF, and BPAF, along with BPA, to assess the developmental and reproductive effects on Daphnia magna. The F0 generation was exposed to bisphenols (BPs) at an environmentally relevant concentration (100 µg/L) for 21 d; then the embryo spawn at day 21 was collected. Behavior traits, the activity of antioxidant enzymes, and gene transcription were evaluated at three developmental stages (days 7, 14, and 21). Notably, body length, heart rate, and thoracic limb beating were significantly decreased, and D. magna behaved more sluggishly in the exposed group. Moreover, exposure to BPs significantly increased the antioxidant enzymatic activities, which indicated that BPs activated the antioxidant defense system. Additionally, gene expression indicated intergenerational effects in larvae, particularly in the BPAF group. In conclusion, BPA analogs such as BPF and BPAF showed similar or stronger reproductive and developmental toxicity than BPA in D. magna. These findings collectively deepen our understanding of the toxicity of BPA analogs and provide empirical evidence for screening safe alternatives to BPA.

Soil Quality Assessment in Farmland of a Rapidly Industrializing Area in the Yangtze Delta, China.

The comprehensive quality assessment of farmland soil is critical for agricultural production and soil ecological protection. Currently, there is no systematic method for conducting a comprehensive quality assessment of farmland soil; subsequently, as the most developed economic area in China, the comprehensive quality assessment of farmland soil in the Yangtze River Delta is lacking. We chose the farmland soil of Suzhou city as the research object. The soil fertility index (SFI) and soil environment index (SEI) were calculated with the membership function and Nemerow index. Finally, the comprehensive assessment of soil quality was achieved with the TOPSIS model. The results showed that the average values of soil pH, SOM, TN, AHN, AP, and AK were 6.44 (slightly acidic), 28.17 g/kg (medium), 1.63 g/kg (rich), 118.16 mg/kg (medium), 38.31 mg/kg (rich), and 160.63 mg/kg (rich), respectively. For the concentrations of heavy metals, including Cr, Ni, Cu, Zn, Cd, and Pb, in 122 soil samples, the percentages exceeding the background values of Jiangsu province were 5.74%, 8.20%, 8.20%, 10.66%, 86.07%, and 84.43%, respectively. Cd and Pb were the main heavy metal pollutants on farmlands. The soil samples with SFI values below the medium level (SFI < 0.6) accounted for 44.26%, and samples with SEI values below the medium level (SEI < 0.6) accounted for 13.12%. The values of the soil quality index (SQI) ranged from 0.171 to 0.996, with an average SQI value of 0.586 (very poor-V), and approximately half of the farmland soil quality in Suzhou city needed to be further improved. In a word, this study provides a theoretical basis and scientific support for the quality assessment and rational utilization of farmland soil.

A modified receptor model for source apportionment of sediment polycyclic aromatic hydrocarbons.

Polycyclic aromatic hydrocarbons (PAHs) have become a serious threat to human health and ecological security due to their persistence and high toxicity. Lake sediments are in a relatively closed environment, so PAHs and other pollutants can be preserved for a long time. Accurate analysis of the sources of PAHs in sediments is an important prerequisite for PAH pollution control. However, the existing PAHs source resolution receptor model (the absolute principal component analysis - multilinear regression (APCA-MLR) and positive matrix factorization (PMF)) has many defects, such as great uncertainty in the process of matrix rotation. In this study, we collected sediment samples from Taihu Lake and tested their PAH content, and the existing receptor model was improved. High PAH contents were distributed in Meiliang Bay, Zhushan Bay, Gonghu Bay and areas close to the shore. "High-High" areas were distributed in Meiliang Bay, Gonghu Bay and areas close to the shore. "Low-Low" areas appeared in the central and southern parts of Taihu Lake. The results show that the improved positive matrix factorization partition computing (PMF-PC) model is significantly better than the APCA-MLR and PMF models in terms of both numerical simulation accuracy and the spatial distribution consistency of PAHs. The correlations (R2) between the measured and simulated values of low-molecular-weight PAHs (L-PAHs), high-molecular-weight PAHs (H-PAHs) and PAHs were 0.992, 0.989 and 0.993, respectively. The contributions of biomass sources, coal combustion sources and petroleum sources to PAHs in Taihu Lake sediments reached 16.7%, 31.7% and 51.6%, respectively. Fossil fuel sources were mainly concentrated in areas near the shore, and the contribution was lower in areas far from the shore. Although the algorithm still needs to be improved, the PMF-PC model may become a useful tool for the source apportionment of PAHs in sediments.

Source Apportionment and Health Risk Assessment of Heavy Metals in Endemic Tree Species in Southern China: A Case Study of Cinnamomum camphora (L.) Presl.

As a developed economic region in China, the problem of heavy metals (HMs) pollution in the Yangtze River Delta has become increasingly prominent. As an important evergreen broad-leaved tree species in southern China, the camphor tree cannot only be used as a street tree but also its various tissues and organs can be used as raw materials for Chinese herbal medicine. In order to explore whether heavy metal contamination in the region threatens the safety of camphor trees as pharmaceutical raw materials, we collected the bark and leaves of the tree most commonly used for pharmaceuticals in Yixing City. Based on the determination of HMs content, the health risks after human intake are evaluated, the sources and contributions of HMs are analyzed, and then the health risks of pollution sources are spatially visualized. The results showed that under the influence of human activities, the camphor trees in the study area had obvious enrichment of HMs, and the over-standard rate of Pb in the bark was as high as 90%. The non-carcinogenic risks of bark and leaves are acceptable, but the carcinogenic risks are not acceptable. The bark had the highest average carcinogenic risk, approaching six times the threshold. The results of Pb isotope ratio analysis showed that the average contribution rate of industrial activities to HMs in camphor trees in the study area was the highest, reaching 49.70%, followed by fossil fuel burning (37.14%) and the contribution of natural sources was the smallest, only 13.16%. The locations of the high-risk areas caused by the three pollution sources in the study area are basically similar, mainly concentrated in the northwest, northeast, and southeast, which are consistent with the distribution of industries and resources in the study area. This study can provide a reference for the precise prevention of HMs pollution of camphor and the safe selection of its pharmaceutical materials.

Observation of the Effect of Focused Psychological Intervention Combined with Standardized Pain Nursing on Postoperative Pain Levels and Depression and Anxiety in Patients with Intestinal Obstruction.

Objective: The purpose of this study was to investigate the effect of targeted psychological intervention combined with standardized pain care on postoperative pain, depression, and anxiety in patients with intestinal obstruction. Methods: 84 patients with intestinal obstruction hospitalized at our hospital from October 2019 to February 2021 were randomly divided into study and control groups. The patients in the control group were treated with routine nursing, and the patients in the study group were treated with focused psychological intervention combined with standardized pain nursing. The pain degree (VAS), depression and anxiety (SDS, SAS) score, sleep quality (PSQI) score, and nursing satisfaction of the two groups before and after intervention were calculated. Results: Before intervention, no significant differences in VAS score between the study and control groups were observed. The VAS score of 6 h, 12 h, 24 h, and 48 h dry prognosis in the study group was lower than that in the control group. There was no significant difference in the scores of SDS and SAS between two groups. After intervention, the scores of SDS and SAS in the study group were lower than those in the control group. After intervention, the scores of daytime dysfunction, hypnotic drugs, sleep disorders, sleep efficiency, sleep time, and sleep quality in the study group were significantly lower than those in the control group. The scores of nursing state, nursing technique, nurse-patient communication, and inspection observation in the study group were higher than those in the control. Conclusion: The intervention of focused psychological intervention combined with standardized pain nursing on patients with intestinal obstruction can effectively relieve their negative emotion and reduce the degree of postoperative pain. In addition, it can improve patients' sleep quality and enhance patients' satisfaction with all kinds of nursing work.

The sources risk assessment combined with APCS/MLR model for potentially toxic elements in farmland of a first-tier city, China.

With the rapid economic development, potentially toxic elements (PTEs) are continuously migrating, transforming, and enriching in farmland through atmospheric deposition and other media, posing threats to food security and human health. At present, there are few quantitative studies on the health risks of PTEs sources in farmland. In this study, absolute principal component score-multiple linear regression (APCS-MLR) receptor model was used to quantify the pollution sources of PTEs in farmland in Suzhou of Yangtze River Delta Economic Zone, China. Combined with geoaccumulation index (Igeo) and health risk assessment model, the source risk of PTEs was further quantified. The results show that Cd has reached the level of unpolluted to moderate polluted (0 < Igeo < 1); the total hazard index (THI) and total carcinogenic risk (TCR) index of PTEs are acceptable for adults, but not for children (THI > 1, TCR > 1 × 10-4). The results of APCS-MLR source apportionment were industrial sources (25.65%), agricultural sources (20.00%), traffic sources (16.81%), and domestic pollution sources (9.71%). The Igeo values of all pollution sources were less than 0, and no ecological risk was caused. The contribution patterns of pollution sources to THI and TCR in adults and children are similar. Industrial pollution sources pose the greatest non-carcinogenic risk to humans, accounting for 47.35% and 47.26% of adults and children, respectively; for carcinogenic risks, domestic pollution sources contribute the most among all identified pollution sources, accounting for 27.71% and 27.73% of adults and children, respectively. In general, this study emphasizes the need to strengthen the supervision of industrial pollution sources and domestic pollution sources in the study area to reduce the health risks to children.

Identification and response analysis of xyloglucan endotransglycosylase/hydrolases (XTH) family to fluoride and aluminum treatment in Camellia sinensis.

BACKGROUND: Xyloglucan endotransglycosylase/hydrolases (XTH) can disrupt and reconnect the xyloglucan chains, modify the cellulose-xyloglucan complex structure in the cell wall to reconstruct the cell wall. Previous studies have reported that XTH plays a key role in the aluminum (Al) tolerance of tea plants (Camellia sinensis), which is a typical plant that accumulates Al and fluoride (F), but its role in F resistance has not been reported. RESULTS: Here, 14 CsXTH genes were identified from C. sinensis and named as CsXTH1-14. The phylogenetic analysis revealed that CsXTH members were divided into 3 subclasses, and conserved motif analysis showed that all these members included catalytic active region. Furthermore, the expressions of all CsXTH genes showed tissue-specific and were regulated by Al3+ and F- treatments. CsXTH1, CsXTH4, CsXTH6-8 and CsXTH11-14 were up-regulated under Al3+ treatments; CsXTH1-10 and CsXTH12-14 responded to different concentrations of F- treatments. The content of xyloglucan oligosaccharide determined by immunofluorescence labeling increased to the highest level at low concentrations of Al3+ or F- treatments (0.4 mM Al3+ or 8 mg/L F-), accompanying by the activity of XET (Xyloglucan endotransglucosylase) peaked. CONCLUSION: In conclusion, CsXTH activities were regulated by Al or F via controlling the expressions of CsXTH genes and the content of xyloglucan oligosaccharide in C. sinensis roots was affected by Al or F, which might finally influence the elongation of roots and the growth of plants.

Temporal and spatial distributions and sources of heavy metals in atmospheric deposition in western Taihu Lake, China.

Heavy metals in atmospheric dust can directly pollute the soil, water and sediment, causing serious harm to human health. In this study, the temporal and spatial distribution characteristics of heavy metals in atmospheric deposition in western Taihu Lake were studied. We established 10 sampling sites to collect atmospheric deposition for two years in different seasons. The atmospheric deposition flux follows the order urban area (95.6 g m-2·a-1) > suburban area (80.2 g m-2·a-1) > forestland (56.8 g m-2·a-1). The concentrations of heavy metals in atmospheric deposition show trends of high values in the winter and low values in the summer and are significantly negatively correlated with distance from the city. The pollution level of Igeo-Cd is 6, which is very high, and that of E-Cd is 219, which means high risk. Heavy metals in atmospheric deposition are mainly taken up via hand-mouth intake, and the harm to children is significantly higher than the harm to adults. The highest health risk assessment values for the four analyzed heavy metals in atmospheric deposition are located near the city and in suburbs (within 5 km of the city center), that is, in areas where human activities are concentrated. The health risk assessment values in areas outside the suburbs are low; these areas are less affected by human activities. The health risk assessment values of heavy metals in the winter and spring are higher than those in the summer and autumn. The Pb isotope ratios show that the main sources of heavy metals in atmospheric deposition and local soil are human activities, such as industry and coal combustion, with less input from natural sources. Heavy metals in atmospheric deposition in the western part of Taihu Lake not only directly threaten local human health but also enter Taihu Lake, posing a serious threat to the Taihu Lake ecosystem.

Application of APCA-MLR receptor model for source apportionment of char and soot in sediments.

Black carbon (char and soot) has attracted increasing attention due to its important role in the global carbon cycle, adsorption of pollutants (polycyclic aromatic hydrocarbons (PAHs) and heavy metals), climate effects and threats to human health. However, few studies have included source analysis of black carbon (char and soot). In this study, the levels of char, soot and PAHs in sediments of West Taihu Lake were assessed, and an absolute principal component analysis followed by multiple linear regression (APCA-MLR) receptor model was used to successfully analyze the material sources of char and soot, providing a new perspective and method for exploring the sources of char and soot. The contributions of coal combustion sources to char and soot are 62.0% and 43.2%, respectively, which are significantly higher than those of biomass combustion sources (13.7% and 19.8%). The contributions of oil combustion sources to char and soot are 24.3% and 37.0%, respectively. The contributions of coal, oil and biomass combustion to char and soot have similar spatial distributions: the coal combustion sources and biomass combustion sources are mainly affected by urban development, which is largely distributed in the northwest of the study area, whereas the oil combustion sources are mainly affected by automobile traffic and lake ports, which are mainly distributed in the west of the study area, and these effects decrease with an increase in offshore distance.

A modified receptor model for historical source apportionment of polycyclic aromatic hydrocarbons in sediment.

Pollution of polycyclic aromatic hydrocarbons (PAHs) in the environment is becoming increasingly serious with the development of the economy. Source analysis is the key step in reducing PAHs pollution in the environment, and existing methods are usually based on receptor models. However, when these methods are applied to the distribution of PAHs in sediments, overestimation or underestimation often occurs. Therefore, this paper proposes an improved model based on principal component analysis and multiple linear regression. The model has been applied to study the pollution of PAHs in sediments of Taihu Lake in China over several decades. Compared with existing models, principal component analysis followed by multiple linear regression of source (PCA-MLRS) can identify specific emission sources and quantify the impact of each emission, and the source resolution accuracy of the strong toxic molecules BaP and DBA is significantly higher than that of other models. Biomass combustion source is the main material source of Phe, Ant, Flu and Pyr in Taihu Lake sediment, and their contribution rates are 85.2%, 44.8%, 58.9% and 62.2%, respectively. The coal combustion source is the main material source of the 5-ring molecule BaP and the 6-ring molecules InP and BP. The contribution rates of coal combustion to BaP, InP and BP are 70.1%, 72.9% and 72.1%, respectively, and this contribution has increased since 1985. The contribution of petroleum oil combustion source and coal combustion source to PAHs in sediments of Taihu Lake is consistent. They are the main sources of heavy molecular PAHs such as BaA, BbF, BkF and DBA, and their contributions are 56.5%, 36.8%, 43.9% and 67.3% respectively. The results are related to the different emission and management characteristics of PAHs from different sources and the different behavior characteristics of low and high molecular weight PAHs in the environment.

Heavy Metals in Agricultural Soils of the Lihe River Watershed, East China: Spatial Distribution, Ecological Risk, and Pollution Source.

Concentrations of cadmium, chromium, copper, nickel, lead, and zinc in agricultural soils at 32 sites in the Lihe River Watershed of the Taihu region, East China, and their potential ecological risks and possible sources were investigated. Enrichment factor analysis demonstrated enrichment in the order Cd > Pb > Zn > Cu > Ni > Cr. The potential ecological risk index and risk assessment code analyses indicated that, of the metals studied, Cd posed the most significant ecological risk in the study area. Statistical analyses, GIS mapping, and enrichment factor analysis suggested that Cd, Pb, Cu, and Zn were derived mainly from anthropogenic sources, including agricultural, industrial, and vehicular emissions, while Cr and Ni were mainly from natural sources. Positive matrix factorization revealed that Cd, Cr, Cu, Ni, Pb, and Zn were sourced from industrial and vehicular emissions (73.7%, 21.3%, 71.4%, 20.3%, 75.0%, and 62.2%, respectively), the agricultural sector (26.3%, 36.3%, 6.8%, 38.9%, 15.7%, and 6.9%, respectively), and parent materials (0%, 42.4%, 21.8%, 40.8%, 9.2%, and 30.9%, respectively). It was recommended that strategies be implemented to reduce industrial point-source pollution.

Determination of influencing factors on historical concentration variations of PAHs in West Taihu Lake, China.

The adsorption of polycyclic aromatic hydrocarbons (PAHs) by components such as elemental carbon (EC), total organic carbon (TOC), and particles is different, and EC and PAHs are good materials for reconstructing historical human activity patterns and pollution conditions. In this study, the effects of EC (soot and char), TOC and particles of different grain size on PAHs in surface sediments were quantitatively analysed, and their historical concentrations in a sediment core from western Taihu Lake were reconstructed. The contents of soot, TOC, clay, EC and char explained 57.2%, 27.6%, 26.0%, 24.0% and 16.4%, respectively, of the PAH concentrations in surface sediments. The correlation between the soot and PAH levels was significantly higher than that between the char, TOC, and clay contents and PAH levels, and PAHs were mainly affected by the local economic development and human activity, as indicated by metrics of population, highway mileage, coal burning, and industrial output. With the development of the economy of the Taihu Lake Basin, the composition of PAHs in the sediments has changed: the proportion of low-molecular-weight PAHs decreased from 42.4% to 17.5%, and that of high-molecular-weight PAHs increased from 58.7% to 82.5%. The concentration of PAHs in pore water from Taihu Lake over the past 100 years was reconstructed and ranged from 43.1 to 961.2 µg L-1, with an average of 180.7 µg L-1. After China's reform and opening up, the concentrations of various PAHs in Taihu Lake changed from safe to chronic pollution levels. The ratios of lead (Pb) isotopes and the diagnostic ratios of PAHs showed that the main sources of PAHs in western Taihu Lake sediments were human activities such as coal and petroleum combustion.

[Elevational Distribution Characteristics of Soil Bacterial Community and Enzyme Activities in Mount Huangshan].

Mount Huangshan has a well-preserved ecosystem and obvious differences in vertical geography, which provide a natural laboratory for studying the altitudinal distribution patterns of soil microbial communities in a mid-subtropical forest ecosystem. The soil bacterial community structure and diversity of the samples collected every 100 m from 670 to 1870 m on the south slope of Mount Huangshan were examined using Illumina MiSeq high-throughput sequencing technology. The soil physicochemical properties and soil enzyme activities of the samples were also measured to explore the relationship between bacterial communities and soil properties as well as enzyme activities. The results showed that ① The contents of soil total nitrogen, available nitrogen, total potassium, and total organic carbon were significantly different across the altitudes (P<0.01) and generally increased as altitude increased. The soil sucrase activities across altitudes were significantly different (P<0.01), and generally increased as altitude increased. However, there was no significant difference in acid phosphatase and urease activities between different altitudes (P>0.05). ② The 12 elevational gradients were divided into three groups:low altitude (670-875 m), medium altitude (1080-1370 m), and high altitude (1460-1780 m). The OTUs in low altitude sites were greater than in high altitude sites but lower compared to medium altitude sites. However, the differences in OTUs across altitude sites were not significant. ③ The soil bacterial community diversity showed a unimodal pattern in a small range of altitudes from 875-1370 m, although no apparent trend was observed at the altitudes from 670-1780 m. ④ There were 7 dominant phyla and 15 dominant orders with a relative abundance of more than 3% in all soil samples. ⑤ Correlation heat map analysis between the top 15 bacterial phyla and soil physicochemical properties as well as enzyme activities showed that soil pH had the greatest effect on the differences in soil bacterial community structure across the different altitudes. Pearson correlation analysis and Partial Mantel test also showed that bacterial community α-diversity (P<0.01) and ß-diversity (Partial Mantel r=0.560, P=0.001) were mainly affected by soil pH. Consequently, soil pH was the key environmental factor determining the soil bacterial community structure and diversity across the different altitudes on Mount Huangshan.

[Effect of nonionic surfactant Tween80 and DOM on the behaviors of desorption of phenanthrene and pyrene in soil-water systems].

Batch experiments were conducted to study the effects of dissolved organic matter (DOM) and nonionic surfactant (Tween80) on the desorption of phenanthrene and pyrene in soil-water systems. The results showed that DOM derived from pig manure and pig manure compost increased the desorption of phenanthrene and pyrene in soil-water systems, and the effect of pig manure compost DOM was better than that of pig manure DOM; with the increase of Tween80, the desorption rate of phenanthrene and pyrene also increased compared with the control, especially at high concentration of Tween80 (150 mg x L(-)). And at this concentration, the desorption rates were increased by 1.7 times for phenanthrene and 6.2 times for pyrene than that of the control. The combined effects of Tween80 and DOM on the desorption of phenanthrene and pyrene were influenced by the concentration of Tween80. When Tween80 at low concentration, the combined effects were not significant. Howerver, with 150 mg x L(-1) Tween80 in soil-water systems, the desorption rates of phenanthrene and pyrene were drastically higher than the sum of DOM and Tween80. The results also indicated that DOMs with high molecular-size fraction ( > 25 000 could attain a higher desorption of both phenanthrene and pyrene in soil-water systems than their lowmolecular-size counterpart (< 1000) under the same experiments conditions.

[Vertical fractionation of dissolved organic matter and its effect on the transport of Cu in Cu-contaminated soils].

The vertical fractionation of DOM and its effect on Cu transport in acidic and calcareous Cu-contaminated soils were studied in column experiments. The results showed that the polarities of DOM derived from green manure and pig manure were obviously decreased by 11.4% and 10.72%, respectively, when they were leached through soil columns, especially in the calcareous soil. Dissolved organic matter can increase the dissolution of copper from the two copper-contaminated soils, but the dissolution effect was influenced by the properties of DOM and soils. For example, the ability of DOM derived from green manure to increase copper dissolution was stronger than that of DOM from pig manure. On average, the amounts of copper into effluent leached by green manure DOM or pig manure DOM in the column packed with a calcareous soil are 4.37 and 3.03 times higher than that in the column packed with an acidic red soil, respectively. In addition, it was observed that Cu dissolution from soils facilitated by DOM was decreased due to microbial degradation of DOM in soils.

[Adsorption of dissolved organic matter in soil and dissolved organic matter effect on the copper precipitation in high pH range].

Batch experiments were performed to study the dissolved organic matter (DOM) derived from green manure and pig manure sorption in acidic and calcareous soils and the effect of DOM derived from green manure and pig manure compost on the precipitation of copper at different pH in solution. The results showed that there was a significant net release of dissolved organic carbon (DOC) in soil (33.58 mg x L(-1) for calcareous soil and 17.17 mg x L(-1) for acidic soil) when a DOC-free solution was added. As the amount of added DOC increased, the release of DOC from soils decreased. This indicates that parts of the added DOC were sorbed by thesoil material and this effect was influenced by DOM's properties and soil properties. In this experiment the initial mass (IM) isotherm was used to describe the DOM sorption in soil which has been shown to be a useful tool for describing the sorption of DOC insoils because it takes into consideration the release of indigenous DOM from soil. As compared to green manure DOM, pig manure DOM had high m and Kd values, which indicated that it had a higher affinity with soil. As compared to that of green manure DOM, the m and Kd values are 0.4241, 2.946 in acidic soil and 0.2846, 1.58 in calcareous soil, respectively. What's more, the results also indicated that the acidic soil with higher Fe-oxide and Al-oxide content exhibited much higher DOC adsorption ability than calcareous soil rich in 2:1 minerals. In this experiment, green manure and pig manure compost DOM were selected to investigate the effects of DOM on the precipitation-dissolution behavior of copper at different pH. It can be found that DOM can inhibit the copper precipitation especially at high pH range because of the formation of DOM-Cu complex. From pH 6 to pH 10, as compared to the control treatment with no DOM added, the precipitation rate average decreased by 43.6% for the treatment with green manure DOM added and 22.65% for the treatment with pig manure compost DOM.