Migration and transfer of chromium in soil-vegetable system and associated health risks in vicinity of ferro-alloy manufactory

Study was carried out to analyze the distribution and migration patterns,soil-to-plant transfer and potential health risks of chromium in soil-vegetable system in areas near a ferro-alloy manufactory in Hunan province.The results show that soils near sewer outlet,sewer channel and in control area are averaged 2 239.5,995.33 and 104.9 mg/kg,respectively.The total Cr has a relative accumulation in soil depth of 200-400 mm near the sewer outlet,mainly enriches in the surface layer（0-200 mm） near the sewer channel and decreases gradually in unpolluted soils.The differential concentration level of enrichment between layers is little.The results also indicate that the three vegetables of celery,lettuce and Chinese cabbage are able to convert the potentially toxic Cr（Ⅵ） species into the non-toxic Cr（Ⅲ） species,and the chromium contents in the edible parts of the vegetables are averaged 11.95 mg/kg.The transfer factors of the three vegetables follow the order：Chinese cabbage lettuce celery.The estimated total daily intake of chromium substantially exceeds the dietary allowable value,which may pose health risks to local population.

Heavy Metal Transfer from Soil to Vegetable in Southern Jiangsu Province, China

Vegetable fields in peri-urban areas receive large amounts of extraneous heavy metals because of rapid urbanization and industrialization in China. The concentrations of Cu, Zn, and Pb in 30 soil samples and 32 vegetable samples, collected from 30 different sites in southern Jiangsu Province of China, were measured and their transfer from soil to vegetable was determined. The results showed that the soil samples had wide ranges of pH （4.25-7.85） and electrical conductivity （EC） （0.24-3.42 dS m^-1）. Among the soil samples, there were four soil samples containing higher Cu and two soil samples containing higher Zn concentrations than those specified in the Chinese Soil Environmental Quality Standard II. However, no vegetable sample was found to contain a high level of Cu or Zn. In contrast, one vegetable sample contained 0.243 mg Pb kg^-1 FW, which was above the Chinese Food Hygiene Standard, whereas the corresponding soil Pb concentration was lower than the Chinese Soil Environmental Quality Standard II. The transfer coefficients of Cu of all vegetable samples exceeded the suggested coefficient range, implying that extraneous Cu had high mobility and bioavallability to vegetables. There was no significant correlation between extractable soil heavy metal concentrations with four kinds of extractants and soil pH, EC, heavy metal concentrations in vegetables and soils, except that soil pH correlated well with the extractable soil Cu, Zn, and Pb concentrations with 1.0 mol L-1 NH4NO3. Moreover, diethylenetriamine pentaacetic acid （DTPA） extraction method was a more efficient method of extracting heavy metals from the soils independent of soil pH and EC than other three methods used.

Capacity and degree of iodine absorbed and enriched by vegetable from soil

To understand the biogeochemical transfer of iodine, the absorbability and bioaccumulation of iodine in tested vegetables(radish, spinach and Chinese cabbage) are examined by applying iodic fertilizer composed of kelp and diatomaceous earth. The experimental results show that when iodine in soil is not excessive, the concentrations of iodine in tested vegetables increase as the content of iodine in soil increases. The absorbability and enrichment degree of iodine in various vegetables and in various parts of the same vegetable are different, which explains that the concentration of iodine in plant is determined by the plant type and the physiological action of plant. The patience order of tested vegetables to excessive iodine is Chinese cabbage>spinach>radish. These results have theoretical and practical significance in opening up a new way for ameliorating poor iodine environment with artificial means.

Analysis on the Change of Vegetation Cover and Its Prediction Method——A Case Study in Eastern Jilin

[Objective] This study aimed to investigate the dynamic changes of vegetation cover and its prediction method. [Method] The NDVl was used as data source to perform the spatial overlay analysis on the vegetation coverage changes of the study area in different time period under the GIS platform, with the aim to reveal the spatial distribution rules of the vegetation cover in Eastern Jilin Province during the recent 10 years. The Markov Model and Grey System G （1, 1） theory model were used to predict the vegetation cover change trend in Eastern Jilin Province. [Result] The vegetation cover increased a little, but staying stable in general. The regions with great changes were mainly around the lake and river. The prediction results of Markov Model and Grey System G （1, 1） theory model were consistent with the observed measurement. [Conclusion] This study provided referential basis for the effective protection of the vegetation coverage in mountainous forest, and important reference value for the scientific decision-making on the forest construction planning in Jilin Province as well as in China and sustainable development of social economy.

Evaluation of Spectral Scale Effects in Estimation of Vegetation Leaf Area Index Using Spectral Indices Methods

Spectral index methodology has been widely used in Leaf Area Index(LAI) retrieval at different spatial scales. There are differences in the spectral response of different remote sensors and thus spectral scale effect generated during the use of spectral indices to retrieve LAI. In this study, PROSPECT, leaf optical properties model and Scattering by Arbitrarily Inclined Layers(SAIL) model, were used to simulate canopy spectral reflectance with a bandwidth of 5 nm and a Gaussian spectral response function was employed to simulate the spectral data at six bandwidths ranging from 10 to 35 nm. Additionally, for bandwidths from 5 to 35 nm, the correlation between the spectral index and LAI, and the sensitivities of the spectral index to changes in LAI and bandwidth were analyzed. Finally, the reflectance data at six bandwidths ranging from 40 to 65 nm were used to verify the spectral scale effect generated during the use of the spectral index to retrieve LAI. Results indicate that Vegetation Index of the Universal Pattern Decomposition(VIUPD) had the highest accuracy during LAI retrieval. Followed by Normalized Difference Vegetation Index(NDVI), Modified Simple Ratio Indices(MSRI) and Triangle Vegetation Index(TVI), although the coefficient of determination R^2 was higher than 0.96, the retrieved LAI values were less than the actual value and thus lacked validity. Other spectral indices were significantly affected by the spectral scale effect with poor retrieval results. In this study, VIUPD, which exhibited a relatively good correlation and sensitivity to LAI, was less affected by the spectral scale effect and had a relatively good retrieval capability. This conclusion supports a purported feature independent of the sensor of this model and also confirms the great potential of VIUPD for retrieval of physicochemical parameters of vegetation using multi-source remote sensing data.

基于改进Mask R-CNN的青菜杂质检测研究

绿叶蔬菜的智能包装加工是实现绿叶蔬菜智能化生产、降低生产成本的重要部分,对绿叶蔬菜在包装加工时的杂质检测是其重要前提。以青菜为研究对象,提出一种基于Mask R-CNN的青菜杂质检测模型。首先采集标注掺杂枯树叶、枯菜叶和碎纸片3种常见杂质的青菜图像1370多张,并通过数据增强的方法扩充建立含有2740张青菜杂质图像的数据集。为减少背景对杂质检测的影响,通过在Mask R-CNN模型中加入协调注意力机制,同时添加全连接层和Dropout层,增强模型特征提取能力,减少过拟合现象,并使用迁移学习方法对模型进行微调。结果表明改进后的Mask R-CNN算法对青菜杂质识别的平均精度均值为99.19%,检测速度为8.45 FPS,检测效果良好,可以满足青菜杂质的检测需求。

北京市售生食果蔬中耐药基因赋存特征及迁移风险

目的调研抗生素耐药基因(antibiotic resistance genes,ARGs)的赋存特征,探讨其在食品安全领域的潜在风险。方法采用高通量定量聚合酶链式反应(high-throughput quantitative polymerase chain reaction,HT-qPCR)技术,对北京市售生食果蔬中ARGs及可移动遗传元件(mobile genetic elements,MGEs)的多样性和存在丰度进行描述,并通过高风险筛查、相关性分析、冗余分析、方差分解分析,探讨ARGs的迁移风险。结果共检出9大类188个ARGs和9个MGEs,丰度范围分别为6.18×10^(3)~1.24×10^(8) copies/g、5.86×10^(3)~3.34×10^(8) copies/g;四环素类、氨基糖苷类、β-内酰胺类、大环内酯-林可霉素-链阳霉素类(macrolide-lincosamide-streptogramin B,MLSB)ARGs分布最广;多重耐药类ARGs丰度最高;涉及的主要耐药机制贡献大小为抗生素灭活>外排泵>细胞保护。其中,苦菊的ARGs检出率最高,青椒的ARGs丰度最高;茄果类、叶菜类ARGs丰度普遍高于根茎类蔬菜;水果类样品中ARGs的检出率和丰度最低。高风险ARGs普遍存在,丰度最高可达7.85×10^(7) copies/g,且氨基糖苷类、磺胺类、四环素类、多重耐药类ARGs具有高迁移风险,整合酶和转座酶两类转移机制共同构成主要驱动因素(46.44%)。结论生食果蔬中ARGs赋存情况严重,具有较高的迁移风险,很可能导致耐药现象的大量产生及扩散,危害人类健康,应引起高度重视。

基于半经验半机理建模的冬小麦LAI反演及长势评估

为了提高无人机遥感对冬小麦叶面积指数(leaf area index,LAI)反演模型的精度与泛化能力,该研究利用无人机搭载多光谱相机获取不同氮素处理和不同复种方式的冬小麦生长实测数据,结合PROSAIL辐射传输模型生成包含机理信息的模拟数据,基于不同组合方式建立了5种LAI反演混合数据集,结合多种机器学习方法,以期构建经验与机理相结合的LAI高精度反演模型。由于LAI反演受近红外波段(near infrared,NIR)反射率影响大,该研究筛选7种与NIR波段相关的植被指数提取冬小麦光谱特征,构建与混合数据集LAI的相关系数矩阵,进一步探究不同光谱特征对冬小麦LAI的影响程度。在此基础上,采用具有代表性和普适性的4种机器学习方法,即贝叶斯岭回归模型、线性回归模型、弹性网络模型和支持向量回归模型,构建不同冬小麦LAI反演模型,用以评估基于半经验半机理数据反演冬小麦LAI的可行性,进一步探索其对不同氮素水平和复种方式的冬小麦长势评估能力。结果表明:1)筛选的与NIR波段相关的植被指数与冬小麦LAI之间存在较强的相关性,其中归一化差异植被指数、增强植被指数、归一化差异红边指数、比值植被指数、红边叶绿素植被指数、土壤调节植被指数与LAI呈正相关,结构不敏感色素植被指数与LAI呈负相关;2)辐射传输模型中体现了冬小麦LAI影响太阳光线传播的机理,结果表明,与实测数据混合建立的模型,具有较强的鲁棒性和泛化能力。相比于其他3种模型,支持向量回归模型在各种数据组合下均取得了较好的LAI预测性能,在C1、C2、C3、C4这4种训练-测试组合的训练集中R^(2)依次为0.86、0.87、0.88、0.91,RMSE依次为0.47、0.45、0.45、0.41;在测试集的R^(2)依次为0.85、0.19、0.89、0.87,RMSE依次为0.45、1.31、0.49、0.50;3)使用支持向量机生成试验区LAI反演图,对4种氮素水平和2种复种方式的冬小麦长势评估,结果表明,适当的施加氮素处理能提高冬小麦LAI值,麦-豆复种方式下的冬小麦LAI值普遍高于麦-玉复种的LAI值。该研究为冬小麦LAI的反演提供了一种有效的方法,并为高效评估冬小麦长势研究提供了参考。

光伏-绿化复合屋面的研究现状与展望

从屋面热湿环境和植被状态、光伏发电效率、水分平衡、能量平衡与热过程模型4个方面对光伏-绿化复合屋面的研究现状进行阐述。结果表明不同气候和空间配置条件下,光伏组件与植被间的相互作用存在动态变化,导致屋面综合性能存在一定的不确定性。最后对光伏-绿化复合屋面工程应用中面临的挑战以及未来的研究方向进行分析和展望,并指出掌握光伏组件与植被之间的相互作用机理是准确预测与优化光伏-绿化复合屋面综合性能的关键。

Scaling,optimisation,and application of vegetation canopy radiative transfer model at microclimate scale

Urban greenery is widely recognised as a strategy to mitigate urban overheating,and its shading capacity is crucial for improving microclimate and thermal comfort.Nevertheless,research on modelling the vegetation canopy radiation transfer(VCRT)process for the microscale is lacking,and most existing VCRT models are taken out from mesoscale models.In this study,we used canopy morphology and structure as an entry point to construct a VCRT model for the microscale,from the mesoscale model.Firstly,100 m and 1000 m were defined as the critical scales by scaling,and the effect of leaf distribution on VCRT was analysed.The VCRT model was made applicable to the microscale by introducing a scattered radiation source term and 6 leaf inclination distribution(LID)functions,and the results showed that the proposed model could improve the accuracy of canopy radiation absorptivity by about 11%.In addition,both leaf area index(LAI)and LID had significant effects on VCRT,and vegetation with LAI above 2 and spreading leaves had better shading effects.It is worth noting that urban greenery has an exciting potential for thermal comfort improvement,with the potential to regulate even extremely hot weather from near"very hot"(148 W/m2)to almost"comfortable"(69 W/m2).This study is a catalyst for improving the predictability of the VCRT process for microclimate and thermal comfort,providing theoretical support and implications for mitigating urban overheating and enhancing urban thermal resilience.

基于辐射传输模型探究机载高光谱激光雷达的植被垂直生化组分探测能力

自然环境下的植被群落,由于各种群之间以及种群与环境间的竞争与选择,常呈现出一定的垂直结构,对于同一植株的不同生长阶段,在垂直方向也有着不同的生理生化参数。对这种三维立体分布特征进行探测,能够进行生态环境立体化定量评价,对森林碳储量估算和生物多样性保护等具有重要意义。传统的被动光学遥感以及激光雷达在植被生化参数垂直探测方面有较大的局限性,而高光谱激光雷达(Hyperspectral LiDAR,HSL)这一新型探测仪器的出现为探测植被生理生化参数垂直分布提供了新的手段。但由于受到硬件方面的限制,HSL在机载平台下对森林复杂立体场景的适用性尚未得到充分研究。故首先基于HSL原型样机在实验室开展小尺度的室内测量,以火炬花植株为目标,验证其对空间信息和光谱信息的一体化提取能力;随后进一步使用三维辐射传输模型构建具有垂直异质性特征的森林场景,模拟机载HSL设备实现森林的高光谱三维点云提取,结合植被指数和随机森林模型对场景中三种不同植被冠层的叶绿素浓度和类胡萝卜素浓度进行反演。结果表明:室内实验证实了HSL回波信息可以有效区分植株不同高度处光谱曲线的差异,火炬花上部红色叶片和下部绿色叶片的归一化植被指数分别小于和大于0.5;基于三维辐射传输模型成功构建了虚拟森林场景的机载HSL高光谱三维点云,在得到的24组植被指数中,有17组指数表现出良好的探测精度(平均绝对百分比误差MAPE<13%);植被叶绿素反演模型R^(2)达到0.93,上层、中层和下层的平均绝对误差MAE分别为6.26、3.40和2.81;类胡萝卜素反演模型R^(2)为0.91,上层、中层和下层的MAE分别为1.59、2.58和0.39。该研究显示出HSL设备是一种立体化提取植被光谱信息的有效手段,在探测森林等复杂植被场景的生化组分垂直分布方面具有巨大的应用潜力。

基于水土资源演变的三峡移民影响区生态碳储量变化特征研究:以重庆市开州区为例

【目的】实现“双碳”目标、践行“两山”理论是新时代生态低碳发展的根本原则。而人类活动强扰动区域水土资源的演变对生态系统碳排放与碳储存的影响尚不明晰。【方法】以三峡库区城镇群的重要组成部分渝东北开州区为研究区,运用回归趋势法分析重庆市开州区植被覆盖的稳定性特征,基于InVest模型固碳模块分析开州区碳储量的变化,分析研究区植被覆盖的演化趋势、碳储量的变化以及社会经济效益随上述情况的变化趋势。【结果】结果表明:2000—2020年,研究区内主要土地利用类型为耕地和林地,达到开州区面积的75%以上。陆地生态系统碳储量空间分布具有很强的空间异质性,整体为东高西低、北高南低的趋势。20 a间,研究区内碳储量增加量主要来源于草地向林地的转变共68.11 Gg、草地向耕地的转变共49.21 Gg,而非建设用地向建设用地转换、非水域转为水域造成碳减少共269.78 Gg。【结论】水土资源的演变较大程度影响了碳储量的变化,且水土资源的利用效率与经济发展呈明显正相关,社会经济发展、水土资源演变和碳库变化三者之间存在着相互影响和相互作用。

塔里木河下游地下水位对植被的影响

对塔里木河下游断流河道2000～2002年9个地下水监测断面和18个植被样地的实地监测资料分析表明,地下水埋深对天然植被的组成、分布及长势有直接关系.地下水位的不断下降和土壤含水率大大丧失是引起塔里木河下游植被退化的主导因子.塔里木河下游的四次输水对其下游地下水位抬升起到了积极作用,河道附近地下水位呈逐级抬升过程,横向影响范围达1000 m左右,纵向上,表现为上段地下水抬升幅度较大(达84%),下段抬升幅度较小(6%).随着地下水位的抬升,天然植被的响应范围由第一次输水后的200～250 m,扩展到第四次输水的800 m.

植被类型对土壤剖面盐分离子迁移与累积的影响

【目的】探讨不同植被类型条件下土壤盐分累积与离子分异特征,对于挖掘、利用盐渍土资源、促进农业可持续发展提供科学依据。【方法】以甘肃省秦安县次生盐渍化果园土壤为研究对象,采用大田试验研究种植大麦、玉米、果树和裸露地块(CK)对土壤剖面盐分离子迁移的影响。【结果】在半干旱盐渍化地区,裸露地块土壤剖面盐分始终处于累积状态,随着时间的推进,盐分累积的强度和深度逐渐增大;种植大麦、玉米,在生育后期具有明显的抑盐、脱盐的功效;而种植果树,土壤盐分累积有两个峰值,第一个峰值出现在5—6月,土壤盐分主要累积在大约10—30 cm土层;第二个峰值在8月中旬,土壤盐分主要累积在30—50 cm土层。【结论】在半干旱地区的农林植被条件下,植被类型影响土壤剖面盐分离子迁移累积的时期、强度和部位。种植大麦、玉米、果树对土壤剖面盐分、Cl-、水溶性Ca2+含量有明显的影响。

锌冶炼厂周围重金属在土壤-蔬菜系统中的迁移特征

采用对应采样方法研究了葫芦岛锌冶炼厂周围土壤、蔬菜中Hg、Pb、Cd、Zn、Cu的含量及其在土壤-蔬菜中的传递,分析了土壤、蔬菜中重金属的来源.结果发现锌厂周围土壤、蔬菜受到重金属的严重污染.蔬菜可食用部分Hg、Pb、Cd、Zn、Cu的含量(以鲜重计)最高可分别达到0.013、5.476、2.8524、1.16和1.515 mg/kg.通过转移因子的比较分析,锌厂周围重金属在土壤-蔬菜中的转移能力为Cd>Zn>Cu>Pb>Hg,重金属从土壤向蔬菜叶片中的转移能力高于蔬菜的其它器官.土壤中重金属主要来源于锌厂周围的大气.蔬菜叶片中的Pb可能部分来源于大气,而汞则主要来源于大气.

准球形葡萄预冷时间的研究

果蔬预冷是冷藏链中一个重要环节 ,适当的预冷时间能保证果蔬质量。通过对巨峰葡萄在预冷时的传热分析 ,建立了集总参数法模型来估算葡萄中心温度达到冷库温度时所需要的时间 ,并通过实验进行了验证。结果表明当冷库内空气流速达到一定时 (大于 1.1m s) ,采用定性尺寸R ,集总参数法能够很好地估算葡萄预冷时间 。

基于辐射传输模型的叶绿素含量定量反演

利用基于叶片内部辐射传输机制的PROSPECT模型模拟大量不同生化含量和叶肉结构的叶片光谱,研究利用高光谱植被指数定量反演叶绿素含量的可行性和精度,并比较各指数的稳定性和抗干扰能力。结果显示,各指数在对叶绿素的敏感性方面相差不大,除三角植被指数(TVI)外,其它指数均随叶绿素含量的增加而减小。叶片水分含量的差异对各指数的影响很小,干物质次之,叶肉结构影响最大。在抵抗干物质影响和叶肉结构影响方面,结构无关色素指数(SIPI)明显优于其它四种指数,吸收中心波深归一化后的面积指数(ABNC)次之。通过使用叶片光学模型的模拟光谱来研究叶绿素含量变化的光谱响应及其影响因素和反演策略,具有较强的理论性和普适性。研究结果与实际观测相吻合,方法简单易行。

耦合辐射传输模型的植被含水量遥感改进监测

基于耦合的叶片与冠层辐射传输模型,研究并使用了改进的植被指数提取植被含水量,以实现植被水分含量的遥感监测.使用PROSAIL模拟的高光谱数据,首先对NDVI、WI、NDWI、MSI、CSI及NDII等已有的植被指数提取含水量进行可行性分析比较.结果显示NDVI不能估算出植被含水量,CSI估算能力也不理想,其余四个指数WI,NDWI,NDII,MSI估算植被含水量时相关系数平方在0.76左右;之后对NDWI提取植被含水量进行了敏感因子分析,结果表明NDWI与MCARI具有较好的线性关系,从而得出改进的植被含水量估算方法.该方法可以较好地去除LAI的干扰,估算的相关系数平方提高为0.97,增加了27%,估算残差由初始的0.0156降低为0.00535,减少了65%.

番茄SSR标记在茄子及其他茄科作物上的通用性分析

【目的】利用已完成测序的番茄基因组发展大量的SSR标记,并将这些标记转移到茄子及其他茄科作物上,节省开发SSR标记的成本.【方法】本研究利用近缘物种转移法分析了番茄SSR标记在茄子及其他茄科作物上的通用性情况.【结果和结论】1 046对番茄SSR引物中有887对能在茄子基因组DNA上扩增出产物,425对引物扩增出的带型在番茄与茄子间相似程度高,标记的通用率为40.6%;EST-SSR比基因组SSR的通用性更好,前者通用率为54.5%,后者为38.9%;414个通用SSR标记被电子定位到番茄染色体上,不同染色体来源的标记通用率明显不同;93对引物在2份用于遗传图谱构建的栽培茄子亲本间表现出多态性;获得的425对通用引物在马铃薯、辣椒、枸杞上通用率分别为96.2%、78.1%、54.1%.

广西某污染区金属元素在土壤-植物系统中的迁移规律

重金属镉(Cd)是一种毒性极强并广泛存在于环境中的有害元素。土壤中的Cd极易被植物吸收并通过食物链对普通人群的健康造成危害。由于Cd在土壤-植物系统的迁移及对人类健康的影响与某些金属元素之间存在着相互作用,研究这些元素对Cd在食物链中迁移及在人体内富集的影响机制成为Cd研究的热点。本研究对广西某污染区的菜田进行了调查,结果表明:污染区蔬菜的Cd、Ca、Cu、Fe、Pb、Zn的浓度明显高于非污染区;不同的蔬菜品种对重金属元素Cd、Cu、Pb、Zn的迁移和积累能力存在着较大差异,不同金属元素的迁移能力依次为Cd>Zn>Cu>Pb;Cd在土壤-植物中的迁移受共存元素的影响。