Solely focusing on the agricultural production function of cultivated land resources is not conducive to the various demands for meeting the UN's Sustainable Development Goals. Recognizing the multifunctionality of cultivated land and understanding the interrelationships between individual functions are crucial for the rational planning and utilization of resources. This paper introduces an "element coupling-function synergy" analytical framework for the sustainable utilization of cultivated land resources. The proposed framework is based on the causal relationships between elements and functions within the cultivated land system. Subsequently, a causal Bayesian belief network was constructed to identify trade-offs and synergies among multiple functions of cultivated land resources in Guangdong, China. The findings reveal trade-offs between food cleanliness and food production/social security, and synergistic relationships among food production, social security, and ecological regulation, as well as among ecological regulation, habitat maintenance and landscape culture. The study area was divided into eight functional zones: Green Agricultural Zone, Agro-inputs Control Zone, Urban Agricultural Zone, Major Grain-producing Zone, Modern Agricultural Zone, Agro-ecological Preservation Zone, Agro-ecological Tourism Zone, Quality Improvement Zone. Multi-objective management plans were formulated for optimizing multifunctional relationships within each zone. The analysis result reveals the importance of nutrient conditions and ecological environments for the sustainable management of cultivated land. Consequently, specific policy recommendations are proposed accordingly. This paper may not only advance understanding of the multifunctionality of cultivated land but can also provide valuable insights for land-use planning to ensure the judicious and sustainable management of cultivated land resources.

Breast cancer remains a serious threat to women's physical and emotional health. The combination therapies can overcome the deficiency of single therapy, enhance the therapeutic effects and reduce the side effects at the same time. In this study, we synthesize a novel nanomedicine that enhanced the therapeutic effects of breast cancer treatment by combining photodynamic therapy and chemotherapy. The doxorubicin (DOX) and photosensitizer methyl pyropheophorbide-a (MPPa) are loaded into the nano-drug delivery system as DPSPFA/MPPa/DOX. In response to near-infrared (NIR) laser, the drugs were quickly released to the cancer cells. The MPPa produces reactive oxygen species (ROS) under the action of photodynamics. Unsaturated fatty acids with ROS promotes lipid peroxidation and the combination of chemotherapy and photodynamic therapy. The data shows that the DPSPFA/MPPa/DOX has a spherical shape, good dispersibility and stability, and the particle size is roughly 200nm. The drug loading capability of DOX is about 13%. Both of MCF7 cell model in vitro and breast cancer model in vivo, DPSPFA/MPPa/DOX showed an excellent anti-tumor effect of 86.9% and without any obvious side effects. These findings might offer potential for a new approach for breast cancer treatment.

Enhancing adsorbent-adsorbate interactions via rational construction of adsorption sites is essential for the capture of the strategic metal indium. Herein, a nanofiber (PCA-Nanofiber) was successfully fabricated for In(III) ions recovery by introducing an electronegative fluorine-containing group to modulate the electronic structure of adsorption sites. Adsorption experiments exhibited that the maximum adsorption of PCA-Nanofiber for In(III) ions (116.3 mg/g) was 3.3 times higher than that of the pre-regulated nanofiber, exceeding most of the reported adsorbents. The PCA-Nanofiber maintained stable performance in five consecutive adsorption-desorption experiments and exhibited excellent selectivity. Furthermore, advanced spectroscopic characterization revealed that the adsorbed complex presented in a six-coordinated octahedral configuration, resembling an anti-triangular prism configuration centered on In(III) ions. The density functional theory demonstrates that the excellent adsorption performance benefits from the electronegative F atoms modulating the electronic microenvironment of the adsorption sites and optimizing the band-gap energy for charge migration, resulting in efficiently driven charge transfer. This work offers ideas for the rational design of adsorption sites in nanofiber from the perspective of regulation of electronic microenvironmental.

Cropland is a comprehensive system influenced by the natural environment and human activities. This article collects the data of cropland use, soil, and other geographic, social and economic factors in the study area and then uses the methods of system analysis, induction and deduction to propose a new research perspective for establishing a cognitive framework and analyzing cropland resources and their functions. The framework is used to assess the rapidly urbanizing region of Guangzhou and investigate the production, ecological, and living functions provided by cropland resources. Synergistic relationships between functions are analyzed using the hot and cold spot methods. The results indicate that the production function of cropland resources in Guangzhou is good, the ecological function is favorable, and the living function is relatively low. A synergistic relationship between the three functions is observed in 91% of areas of Guangzhou, whereas a balanced relationship occurs in some areas of the southern part of Zengcheng, the northwestern and northeastern parts of Conghua, and the western part of Nansha. This research provides guidance for managing cropland resources and ensuring their sustainable utilization.

In this study, a simple, rapid and sensitive method was developed for the simultaneous determination of chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean using liquid chromatography-triple quadrupole mass spectrometry (LC-MS/MS). Analytes were extracted with acetic acid solution, purified on an HLB column, and then filtered through a 0.2 μm hydrophilic microporous filter membrane. They were then separated on an IC column using a separation phase consisting of polyvinyl alcohol particles with quaternary ammonium groups. The mobile phase optimised with water was denoted as mobile phase A and that optimised with 200 mmol L-1 ammonium bicarbonate solution containing 0.05% ammonium hydroxide was denoted as mobile phase B. The residues were detected by tandem mass spectrometry with negative electrospray ionization in a multi-reaction monitoring mode. The correlation coefficient (R ≥ 0.997) showed good linear regressions for all analytes in water as well as in maize and soybean matrices with a wide dynamic range of 0.001 to 0.5 mg L-1 for calibration. The mean recoveries (RSDs) of the analytes were in the range 85.0-106.4% (5.5-14.9%), 81.7-109.5% (2.7-11.0%) and 74.7-104.4% (2.9-6.1%) at three concentration levels (0.05, 0.1 and 1 mg kg-1) for the interday test (n = 15). The limit of quantification (LOQ) and detection (LOD) of the method for different matrices were 0.01 and 0.003 mg kg-1, respectively. In conclusion, the established analytical approach has high sensitivity and good accuracy and precision and is suitable for monitoring chlormequat, fosetyl-aluminium and phosphonic acid residues in maize and soybean.

Vegetation plays an important role in gully headcut erosion processes. However, it is still unclear how vegetation in the upstream area affects gully headcut erosion processes by changing the hydraulics. A series of in situ inflow scouring experiments were conducted on bare land plots and vegetation plots (including the upstream area, headwall, and gully bed) planted with Bothriochloa ischaemum (BI), Agropyron cristatum (AC), and Medicago sativa (MS) with clustered stems and Artemisia gmelinii (AG) with erect stems to investigate the influence of vegetation on the hydrodynamic parameters involved in gully headcut erosion processes. The results showed that, compared with bare land, vegetation increased the Manning roughness coefficient (n) and Darcy-Weisbach friction factor (f) in the upstream area by 0.2-2.5 times and 0.9-9.6 times, respectively, but reduced the runoff velocity in the upstream area and gully brink. However, the jet flow velocity at entry into the plunge pool increased rapidly after passing through the gully head. The influence of vegetation with clustered stems on roughness and runoff velocity was greater than that of vegetation with branched stems. At 3.6 m3/h inflow discharge, vegetation can increase the runoff shear stress of the upstream area. The energy consumption of the gully head, upstream area, and gully bed accounted for 74 to 76 %, 19 to 21 %, and 4 to 7 % of the total energy consumption, respectively. The four vegetation treatments reduced the gully headcut soil loss by 31 to 81 %, among which MS exhibited the highest reduction. The soil loss rate was positively correlated with the jet flow velocity and its kinetic energy, and the correlation was the best (R2 of 0.934 and 0.935, respectively, P < 0.01), presenting a logarithmic trend. These results are helpful to deepen the understanding of the roles of vegetation in regulating runoff hydraulic action during gully headcut erosion.

High nature value farmland (HNVf) plays an important role in improving biodiversity and landscape heterogeneity, and it is effective in curbing soil non-point source pollution and carbon loss in sustainable eco-agricultural systems. To this end, we developed high-resolution (2 m × 2 m) indicators for the identification of potential HNVf based on GF1B remote sensing imaging, including the land cover (LC), normalized difference vegetation index (NDVI), Shannon diversity (SH), and Simpsons index (SI). The statistical results for LC with high resolution (2 m × 2 m) showed that there was 41.05% of intensive farmland in the study area, and the pixel proportion of the HNVf map (above G3) was 44.30%. These HNVf patches were concentrated in the transition zone around the edge of the intensive farmland and around rivers, with characteristics of HNVf type 2 being significantly reflected. Among the real-life areas from Map World, elements (i.e., linear forests, rivers, and semi-natural vegetation etc.) of HNVf accounted for more than 70% of these regions, while a field survey based on potential HNVf patches also exhibited significant HNVf characteristics in comparison with intensive farmlands. In addition, from 2002 to 2020, the total migration distance of the gravity center of intensive farmland in the study area was 7.65 km. Moreover, four landscape indices (patch COH index, landscape division index, SH, and SI) slowly increased, indicating that the species richness and biodiversity were improved. It was also found that a series of ecological protection policies provide effective guarantees for an improvement in species diversity and the development of HNVf in the study area. In particular, the average contents of As, Cr, Cu, Ni, and Zn in the HNVf were 20.99 mg kg−1, 121.11 mg kg−1, 21.97 mg kg−1, 29.34 mg kg−1, and 41.68 mg kg−1, respectively, which were lower in comparison with the intensive farmland soil. This is the first HNVf exploration for landscape and soil pollution assessment in a coastal delta in China, and could provide powerful guidance for the ecological protection of farmland soil and the high-quality development of sustainable agriculture.

Vegetation restoration is the most important factor to restrain soil and water loss in the Chinese Loess Plateau, and its effect is long-term. Among them, the coupling and coordination relationship between vegetation and soil is the key to the smooth implementation of ecological restoration and the project of returning farmland to forest and grassland. However, people have neglected whether the choice of vegetation restoration method is suitable for the development of ecological environment in this region, and whether vegetation and soil coexist harmoniously. In this paper, the typical watersheds with similar terrain environment but different vegetation restoration methods were selected as the research objects, which were Dongzhuanggou (natural restoration, NR) and Yangjiagou (artificial restoration, AR). Through vegetation investigation and soil physical property experiment, the comprehensive evaluation function was used to quantify the impact of restoration methods on vegetation characteristics and soil properties, and the vegetation-soil coupling model was used to explore the coordinated development of vegetation and soil under different restoration methods. The results showed that there were significant differences between the two restoration methods in terms of vegetation characteristics (P < 0.05). The vegetation diversity indices of NR were 1.59-4.81 times that of AR. For root characteristic indices, NR was 1.05-2.25 times that of AR. For soil physical properties, there was no significant difference between the two restoration methods (P > 0.05). The comprehensive evaluation function of vegetation (VCE) and soil (SCE) under NR were 0.74 and 0.42, respectively, while those under AR were 0.55 and 0.63, respectively. The comprehensive function showed that the vegetation population performance under NR was slightly better than that under AR, while the soil restoration effect was opposite. Under the two restoration methods, the vegetation-soil coupling relationship was barely coordinated (NR: 0.53; AR: 0.54), and both were the intermediate coordinated development mode. The vegetation diversity, tending level and soil management level should be improved simultaneously during the process of vegetation restoration on the Chinese Loess Plateau.

Abstract To evaluate the impacts of vegetable and soil variables on phytoaccumulation of arsenic (As), cadmium (Cd) and chromium (Cr) and identify their interactions and predictors, 33 paired soil-vegetable samples were collected from the production areas of celery (Oenanthe javanica), green onion (Allium), pak choy (Brassica rapa subsp. chinensis), rape (Brassica campestris L.) and spinach (Spinacia olearacea) in the Wuqing District of Tianjin, China. The concentrations (mean ± sd in mg kg -1 ) of As, Cd, and Cr were 12.9 ± 2.4, 0.21 ± 0.19, 68.2 ± 11.2 in soils, respectively, higher than their soil backgrounds, and 0.19 ± 0.13, 0.17 ± 0.11, and 1.33 ± 0.94 in shoots (leaves & stems) of all vegetables, respectively. Only Pak Choy’s Cd was significantly higher than its soil concentration and threshold. All vegetables, except green onion, with the lowest concentration of As, Cd, and Cr have been heavily contaminated with Cr. For all vegetables except spinach, Cd concentration in shoots can be well predicted with 0.1M HCl extracted soil Cd (clCd) (R 2 > 0.75) with soil clNi; and shoot Cr concentration with shoot Fe (stFe) for celery, pok choy, rape, and spinach (R 2 > 0.90).Generally, the concentration of As, Cd, and Cr in shoots depends not only on the availability of their specific forms in soil and soil pH but also on the interactions with other elements (especially Fe) in shoots, despite their variations with vegetable species. Both Cd and Cr have a high accumulation potential, which can be better predicted with either 0.1M HCl extractable soil Cd or Fe concentration in shoots. So, how a trace element interacts with other ingredients and its specific form in the soil should be seen as essential factors in how it gets into the shoots.

With the development of human society, the cultivated land resources' utilization has become more diversified, and the multifunction of cultivated land is critical to meet the human demand. However, the studies on the multifunction of cultivated land are mostly based on the data of single time node or discontinuous years, which the results may be influenced by abnormal function years. To assess the multifunction of cultivated land and its trade-off/synergy relationships accurately and objectively, this study uses continuous long time series data to analyze multifunctionality of cultivated land. Firstly, the Long short-term memory (LSTM) method was applied to predict the data of 2021–2030 based on the data from 2010 to 2020. Then, the Theil-Sen Median method was used to analyze the spatiotemporal evolution trends of the multifunction of cultivated land from 2010 to 2030. Secondly, based on the trends, the long time series cultivated land function trade-off/synergy degree (LCFTD) was constructed to explore the stable trade-off/synergy relationships among functions. Finally, the cultivated land resources were divided into zones based on the spectral clustering. This study analyzed the multifunction of cultivated land in Guangdong from 2010 to 2030. (1) The multifunction of cultivated land had spatially heterogeneous and temporally fluctuating. (2) The production-ecological, ecological-life, and production-life functions were all dominated by synergy during 2010–2020. Without changing the current utilization state of cultivated land resource, the trade-off among functions will increase in the future (2021–2030). (3) The cultivated land was divided into five type zones: stable development, production core, ecological conservation, comprehensive lifting, and fallow renewal. The LCFTD can better avoid the influence of abnormal function years, and the long time series data can also predict the future development trend reliably. This study idea can help to formulate long time cultivated land management policies and achieve the goal of sustainable development of cultivated land resources.

Gully head is the main active part of gully erosion, which seriously affects the occurrence of gully headcut erosion. To investigate root distribution and soil physical and mechanical characteristics of typical vegetation gully head, we analyzed the infiltration, root distribution, physical and mechanical properties of soil-root complex of soil in different layers (0-1 m) in natural restoration gully head and artificial restoration gully head. The results showed that the variability of soil bulk and total porosity among different vegetation gully heads was low, with bulk density ranging from 1.10 to 1.37 g·cm-3 and total porosity ranging from 48.3% to 58.4%. Infiltration index of different vegetation gully heads generally decreased with increasing soil depth. The infiltration rate of different soil layers in natural restoration gully head tended to stabilize in 20-30 min, while that of artificial restoration gully head tended to stabilize in 40 min. The infiltration capacity and average infiltration rate of artificial restoration gully head were generally higher than those of natural restoration gully head in all soil layers. Root length density, root surface area density, and average diameter all tended to decrease with increasing soil depth. Except for the 20-40 cm soil layer, root length density, root surface area density and average diameter of natural restoration gully head were all lower than those of artificial restoration gully head. Root system of both vegetation gully heads mainly consisted of 0-0.5 mm roots, accounting for 84.2%-93.6% of the total root length. In the vertical depth, with the increases of water content, the cohesion force decreased linearly with the deepening of soil layer, ranging from 0.42 to 22.67 kPa. The average cohesion force of artificial restoration gully head was higher than natural restoration gully head at each level of water content. The study revealed the effects of vegetation on the gully head cut erosion, which could provide scientific basis for the effective prevention and control of soil erosion in the region.

The deployment of scientific and reasonable cultivated land quality (CLQ) monitoring points can provide timely and accurate information on the current situation and changes in CLQ, which is highly important to protect national food security. The conventional methods of selecting CLQ monitoring points are based on the CLQ of land use patches. As there may be different grades of large patches, being selected as monitoring points reduces the reliability of monitoring CLQ. Moreover, the conventional monitoring point deployment method mainly considers only CLQ and ignores road accessibility and terrain as factors, resulting in the inaccessibility of some monitoring points. Therefore, to improve the reliability of CLQ monitoring, this study presented a novel approach for deploying CLQ monitoring points. First, the pixel-scale CLQ was estimated using the genetic algorithm-back propagation neural network (GA-BPNN) model based on the Landstat8 data with 30 m spatial resolution. Second, the stratified sampling model was used to determine the optimal sample points. Finally, the improved spatial simulated annealing algorithm (ISSA), considering both slope and road accessibility, was applied to optimize the location of monitoring points. This study was conducted in the Conghua District of Guangzhou, Guangdong Province, China. The results highlighted that (1) compared to the accuracy of measured CLQ, the accuracy (R 0.63, RMSE = 79.32, and NRMSE = 13.77%) of CLQ estimated using the remote sensing technique was reliable, and the pixel-scale CLQ data was more reasonable than the patch-scale CLQ data with different grades. (2) A total of 132 monitoring points were finally identified in the study area based on the stratified sampling model. (3) When compared with those of the spatial simulated annealing algorithm (SSA) and the standard grid method, the approach proposed in this study had a higher total score (F = 94.61). Moreover, the obtained sample points were mainly located near roads and flat terrain. This can effectively avoid the inaccessible places. Thus, the results based on the novel approach proposed in this study provide a scientific basis and technical support for obtaining the optimal CLQ monitoring points.

Cultivated land fragmentation (CLF) is a key obstacle to agricultural development and has a strong relationship with regional food security and global sustainable development. However, few studies have analyzed the spatio-temporal distribution pattern and evolution characteristics of CLF and the complex interactions among their influencing factors in rapidly developing regions. In this study, first, the GlobeLand30 datasets were used to obtain characteristic parameters of cultivated land in counties in Guangdong Province in 2000, 2010, and 2020. Then, the linear weighted comprehensive evaluation model based on the principal component analysis (PCA) was used to measure the extent of CLF. Finally, the exploratory spatial data analysis (ESDA) was used to analyze the spatio-temporal distribution pattern and evolution characteristics of CLF, and geodetector (GD) and random forest (RF) models were used to explore the factors influencing the spatial difference in CLF. The results showed that the spatial differences in the distribution of cultivated land resources in Guangdong Province are relatively large and the extent of agglomeration is generally low. The extent of CLF on the county scale is mainly medium and higher. The overall spatial distribution shows an increasing trend from the south to the north and from the west to the east, and the spatial distribution pattern with agglomeration and randomness remains relatively stable. From 2000 to 2020, the overall CLF continued to intensify and the evolution of CLF on the county scale mainly increased. The spatial difference in CLF is the result of that based on the natural environment and influenced by factors such as social, economic, and agricultural development. The interaction between influencing factors is very strong, dominated by nonlinear enhancement. The results are of great significance for promoting the intensive and efficient utilization of cultivated land resources and sustainable regional development.

耕地是人类改造和利用地表而形成的最古老和最广泛的人地系统,耕地质量是耕地系统诸要素耦合状态的表达,耕地资源是在一定时间、技术和经济条件下耕地开发利用价值的体现.本文厘清了耕地系统、耕地质量、耕地资源认知内涵与演进过程,解析了耕地资源的"自然-人文"构成要素与耦合关系、"水平-垂直"结构特征与形成机理、"生产-生态-生活"功能协同与转换关系、"物质-能量-信息"交换过程与响应机制,以及"经济-生态-社会"服务价值与演变规律,构建了"二维要素-三重功能-多元价值"的耕地资源认知系统,提出了系统认知耕地资源的新思路,解构了耕地资源内部机制与外部价值,以期为耕地保护与质量提升及自然资源资产"两统一"管理提供理论依据,推动高质量跨越式发展的耕地保护与资源利用新格局构建.

Current understanding of toxicity mechanisms of nanoparticles is still far from comprehensive, partly because of the neglect of control factors such as the dependence of mechanism activation on the exposure dosage and particle size. To reveal molecular mechanisms of silver nanoparticle (AgNP) toxicity, the model ciliate Paramecium multimicronucleatum was exposed for 12 h to different concentrations of AgNPs with particle size of 20 nm (0.08, 0.12, and 0.30 mg/l) and 40 nm (0.08 and 0.30 mg/l). Transcriptomes of the tested ciliates were then analyzed based on dendrograms of gene expression, Gene Ontology (GO) terms, KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways, and up- and down-regulated genes. Results showed that: (1) toxicity mechanisms of AgNP revealed by analyses of GO and KEEG were significantly involved in the metabolic pathways of nutrients and the biosynthesis of macromolecules; (2) the top five up-regulated genes were mainly related to biological oxidation, biosynthesis, and oxidative stress, while top five down-regulated genes were mainly related to glycolysis; (3) activated mechanisms varied both in quantity and in type with dosages and particle sizes of AgNPs; (4) AgNP-treatments with different exposure dosages and particle sizes can produce the same toxicity in terms of 12 h-EC50, but the underlying molecular mechanisms differed significantly. In brief, this study provides insights into the molecular mechanisms of AgNP toxicity through transcriptome analyses and confirmed their dependence of activation on the exposure dosage and particle size of AgNPs.

根据耕地质量的空间分布特征优化监测样点布局,可提高耕地质量的监测效率和准确性.本研究筛选与耕地质量协同变化的环境因子作为辅助变量,利用地统计学方法分析耕地质量的空间变异特征,采用协同克里格法优化耕地质量监测样点的布设.结果表明:利用与耕地质量相关性较好的地下水位为辅助变量,在不同规格网格的样点布设下,协同克里格在最适(5 km×5 km)网格尺度下得到66个监测点的插值精度,优于普通克里格在小(2 km×2 km)网格尺度下得到390个监测点的插值精度;而在相同规格网格的样点布设下,协同克里格方法得到监测点的插值精度均优于普通克里格.研究表明,结合易于获取的辅助变量信息的协同克里格方法可优化耕地质量监测点布设,得到更少的监测点的样点方案,在耕地质量监测中可实现减少成本的同时提高监测精度.

Toxic trace elements in farmland soils are potential threats to human health. In this study, we collected soil samples from the farmlands of southern Guangzhou. We used a sequential indicator simulation (SIS) to deal with the problem of skewed distribution in the sample data. We assessed the human health risks, as well as the uncertainties, of five toxic trace elements: arsenic (As), cadmium (Cd), chromium (Cr), lead (Pb), and mercury (Hg). The results were as follows: (1) The risk indices of two trace elements (Cd and Hg) were less than the standard threshold, which means that there was no human health risk due to Cd and Hg in the study area. However, the maximum risk indices of As, Cr, and Pb exceeded the standard threshold. In particular, the maximum risk index of Pb was twice the standard threshold; (2) The risk probabilities of As and Cr were less than 25% in most areas, and only a few parcels of farmland have a 100% risk probability. The risk map of Pb was used to identify contiguous areas of high-risk probability (i.e., 75%–100%) in the center of the study area. (3) E-type estimation by the SIS method overestimates the risk when the number of samples with concentrations above the threshold have a large proportion of total samples. Our conclusions are as follows: (1) The simulation results show that areas with high-risk indices were concentrated in the Panyu District, which is close to the Pearl River and the core urban area of Guangzhou; (2) Except for Pb, these trace elements are not likely to pose health risks in southern Guangzhou; (3) This study considers the risk probability found with the SIS method to be more reliable for visualizing regional risk.

The heavy metals in soil have serious impacts on safety, ecological environment and human health due to their toxicity and accumulation. It is necessary to efficiently identify the risk area of heavy metals in farmland soil, which is of important significance for environment protection, pollution warning and farmland risk control. We collected 204 samples and analyzed the contents of seven kinds of heavy metals (Cu, Zn, Pb, Cd, Cr, As, Hg) in Zengcheng District of Guangzhou, China. In order to overcame the problems of the data, including the limitation of abnormal values and skewness distribution and the smooth effect with the traditional kriging methods, we used sequential indicator simulation method (SISIM) to define the spatial distribution of heavy metals, and combined Hakanson index method to identify potential ecological risk area of heavy metals in farmland. The results showed that: (1) Based on the similar accuracy of spatial prediction of soil heavy metals, the SISIM had a better expression of detail rebuild than ordinary kriging in small scale area. Compared to indicator kriging, the SISIM had less error rate (4.9%-17.1%) in uncertainty evaluation of heavy-metal risk identification. The SISIM had less smooth effect and was more applicable to simulate the spatial uncertainty assessment of soil heavy metals and risk identification. (2) There was no pollution in Zengcheng's farmland. Moderate potential ecological risk was found in the southern part of study area due to enterprise production, human activities, and river sediments. This study combined the sequential indicator simulation with Hakanson risk index method, and effectively overcame the outlier information loss and smooth effect of traditional kriging method. It provided a new way to identify the soil heavy metal risk area of farmland in uneven sampling.

Understanding dose-responses is crucial for determining the utility of biomarkers in ecotoxicity assessment. Nitrofurazone is a broad-spectrum antibiotic that is widely used in the aquaculture industry in China despite its detrimental effects on ecosystems. Potential dose-response models were examined for the effect of nitrofurazone on two antioxidant enzymes, superoxide dismutase (SOD) and glutathione peroxidase (GPx), in the ciliated protozoan Euplotes vannus. This was achieved by measuring enzyme activity and gene expression profiling of SOD and GPx in ciliate cells exposed to nitrofurazone at doses ranging from 0 to 180mgl-1 for 6h, 12h, 18h and 24h. Dose-response dynamics were characterized by mathematical models. Results showed that: 1) dose-response patterns differed significantly among the tested endpoints, nitrofurazone concentrations and durations of exposure; 2) GPx activity was the best candidate biomarker because of its linear dose-response relationship; 3) SOD activity and mRNA relative expression levels of GPx and SOD are also candidate biomarkers but their dose-responses were non-linear and therefore more difficult to interpret; 4) partitioning the dose-response dynamic model by piecewise function can help to clarify the relationships between biological endpoints. This study demonstrates the utility of dynamic model analysis and the potential of antioxidant enzymes, in particular GPx activity, as a candidate biomarkers for environmental monitoring and risk assessment of nitrofurazone in the aquaculture industry.

Three types of biochars, poplar branch biochar (PBC), water hyacinth biochar (WHC), and corn straw biochar (CSC), were prepared in a fixed-bed pyrolyzer at different pyrolysis temperatures (300-700℃). The effects of biochar species, pyrolysis temperature, and biochar addition on adsorption characteristics of typical heavy metals (HMs) such as Pb and Zn in vegetable soil (collected from a lead-zinc-silver mining area, Nanjing, China) were investigated. The adsorption mechanism of biochar on HMs was discussed based on the analyses of pore structure, XRD, and FTIR of biochars. WHC biochar showed the best adsorption ability at the same experimental conditions with adsorption efficiencies on Zn and Pb of 21.83% and 44.57%, respectively. The relative adsorption capacities of Zn and Pb were 227.65 μg·g-1 and 363.76 μg·g-1 at the pyrolysis temperature of 500℃ and biochar addition of 5%. The adsorption efficiency of biochar on HMs in soil increased gradually with increasing pyrolysis temperature. WHC biochars prepared at 500℃ and 700℃ had similar adsorption capacities on Zn and Pb in soil indicating that the moderate pyrolysis may be a good choice for WHC with better physicochemical properties. Increasing the amount of WHC addition benefits the adsorption efficiency of HMs in soil, but does not increase the adsorption capacity. The adsorption efficiency of Pb in soil reaches 93.93% by adding 10% of WHC into the soil sample. The combined analyses based on the physicochemical properties of biochar and the results of soil HMs adsorption experiments suggest that ion exchange and complexation are prevailing mechanisms of the remediation of HM-contaminated soil by WHC biochars.