The difference in soil organic carbon （SOC） between karst and non-karst areas affects the accurate assessment of soil carbon sinks at the county scale， making it a hot and difficult topic in soil carbon research in karst areas. Taking Wenshan County， a typical karst area in southeast Yunnan Province， as an example， a 1 km×1 km grid sampling method was used to conduct the spatial differences in SOC content， density， and storage in the 0-20 cm soil layer between karst and non-karst areas. The impacts of different land use patterns， karst rocky desertification， elevation， and soil physicochemical properties on surface SOC were also explored. The results showed that the SOC storage in the 0-20 cm soil layer was 12.619 million tons， with a distribution pattern of high in the west and low in the central and northern regions in Wenshan County. The mean values of ω（SOC） and SOC density in non-karst areas were 20.88 g·kg-1 and 4.93 kg·m-2， respectively， which were 27.94% and 23.55% higher than those in karst areas （P < 0.01）. Significant differences in ω（SOC） were observed under different land use types， with shrubland （24.58 g·kg-1） > grassland （20.92 g·kg-1） > forestland （20.52 g·kg-1） > orchard （19.89 g·kg-1） > other woodland （18.87 g·kg-1） > dryland （16.16 g·kg-1） > paddy field （15.58 g·kg-1）. The SOC in shrubland， grassland， and other woodland in non-karst areas was 35.95%-66.52% higher than that in karst areas， indicating that abundant plant litter input in non-karst areas contributed to SOC accumulation. Karst rocky desertification was mainly distributed in the northern， central， and eastern regions of Wenshan County， which was consistent with the distribution of low SOC areas （8.0-15.0 g·kg-1）. The ω（SOC） in mild， moderate， and severe karst rocky desertification areas ranged from 12.98 to 15.55 g·kg-1， significantly lower than that in non-rocky desertification and potential rocky desertification areas （17.34-17.82 g·kg-1， P < 0.01）. Geographical detection analysis showed that the single-factor explanatory power of soil total nitrogen （TN） content for SOC spatial differentiation exceeded 0.70， followed by elevation， soil bulk density， and C/P， with single-factor explanatory powers ranging from 0.31 to 0.52. The interaction effects of TN and C/N， as well as TP and C/P， had explanatory powers of 0.73 to 0.95 for SOC， indicating that soil nutrients such as nitrogen and phosphorus had important impacts on SOC. Due to the influence of karst rocky desertification， the ω（TN） in the karst area of Wenshan County was 1.54-2.10 g·kg-1， which was 11.47%-27.25% lower than that in non-karst areas， resulting in lower explanatory powers of the aforementioned influencing factors and their interactions for SOC in karst areas compared to those in non-karst areas. This study provides a scientific reference for assessing soil carbon sinks at the county scale in karst regions.

Karst wetland plays an important role in the ecological environment; however, due to the existence of karst pipeline, pollutants can threaten the underground environment through the highly developed karst pipeline. Therefore, understanding the pollution characteristics of the karst surface environment is the premise of pollution ecological risk assessment and prevention. In this study, 24 organochlorine pesticides (OCPs) were analyzed to study the concentration, composition, source, and risk of OCPs in water and surface sediments in the Huixian Wetland of Guilin. The results showed that:the concentration of OCPs in water ranged from 3.17 ng·L-1 to 92.50 ng·L-1, and the concentration of OCPs in sediment ranged from 1.16 ng·g-1 to 219.52 ng·g-1, showing the main pollution characteristics of HCHs and DDTs. The concentration of OCPs in water was higher in the wet season than that in the dry season. The concentration of OCPs in sediments was higher in the dry season than that in the wet season. The isomer ratios revealed that OCPs in the study area were mainly derived from long-term degradation residues, and some sites had new input of lindane. Based on Monte Carlo simulation, the human health risk assessment of the study area showed that the 95% quantile carcinogenic risk of OCPs in water was greater than 1×10-6, with potential but acceptable health risk. The non-carcinogenic risk was lower than 1, which indicated that the level of OCPs residues in the water in the study area was not enough to cause non-carcinogenic risk to the human body.

通过测定贵州丹寨县主要水稻种植区30件水稻土及对应的水稻中硒和重金属的含量,分析硒和重金属Cd、Hg、As、Pb在根系土及对应水稻中的分布特征,研究了土壤有机质和pH对硒和重金属在土壤-水稻系统中迁移的影响.结果 表明:该地区水稻根系土中硒含量变化范围为0.27～0.98 mg/kg,平均值为0.65 mg/kg,70％的样品达到富硒土壤标准,但是仅23.3％水稻籽实样品达富Se大米标准.土壤重金属污染风险较大,特别是Hg和Cd,其中80％的样品Hg超《土壤环境质量农用地土壤污染风险管控标准(试行)》(GB 15618-2018)中污染风险筛选值,但水稻籽实中尚无重金属超标现象.水稻根系对硒的富集能力相对最强,其次为茎、叶和籽实.重金属也主要积累在根系中.水稻籽实Se含量与土壤Se总量的相关性不显著,与土壤pH和有机质含量呈显著负相关.水稻籽实中Cd与土壤Se和pH呈显著的负相关关系.土壤中As和Hg向水稻的迁移则主要受总量的控制.水稻各部位Se的吸收能力与土壤重金属存在极显著负相关性,据此可采取措施如降低土壤中的重金属尤其是Cd和Hg的含量及减少有机肥的施用来提高Se在籽实中的积累.

分析云南广南县土壤锗的地球化学特征及土壤锗富集的影响因素,为当地的农业生产和富锗农产品的开发提供理论依据.在全区范围内根据不同的土地利用类型、成土母岩及地貌类型,采集土壤样品共1985件,经晾干、研磨、过筛后测定土壤锗及有机质、pH、Cd、Pb、Hg等元素的含量.结果表明:表层土壤锗的含量变化范围为0.730～4.010 mg/kg,平均值为1.648 mg/kg,为富锗土壤,富锗面积超过60％且主要分布在岩溶地区;不同的土地利用类型、地貌类型和成土母岩对土壤中锗含量均有不同程度的影响,锗在不同土地利用类型土壤中平均含量表现为裸地>灌木林地>旱地>水田;相关性分析表明,锗与有机质、pH、Cd、Hg和CaO显著相关,但在不同的类别中存在一些差异;偏碱性的土壤环境、有机质和亲硫重金属元素容易造成锗的富集.

Potentially toxic elements (PTEs) in Chinese agricultural soils, including those in some heritage protection zones, are serious and threaten food safety. Many scientists think that these PTEs may come from parent rock. Hence, at a karst rice-growing agricultural heritage area, Babao town, Guangnan County, Yunnan Province, China, the concentrations of eight PTEs (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) were determined in 148 surface soil, 25 rock, and 52 rice grain samples. A principal component analysis (PCA) and hierarchical cluster analysis were used to divide the surface soil into groups, and inverse distance weighting (IDW) was used to analyze the spatial distribution of PTEs. Soil pollution was assessed with the geoaccumulation index (Igeo). The results show that Cd, Hg, Zn, and Cr were polluting the soil (average Igeo > 0). The highest concentration of PTEs was distributed in the southwest of Babao town in the carbonate rock area, which had the highest pH and soil total organic carbon (Corg), Mn, and TFe2O3 contents. PCA biplots of soil samples showed that the carbonate rock area was associated with the most species of PTEs in the study area including Pb, Cd, Hg, As, and Zn. The clastic rock area was associated with Cu and Ni, and the lime and cement plants were associated with CaO, pH, Corg, TC, and aggravated PTE pollution around factories. In high-level PTE areas, rice was planted. Two out of 52 rice grain samples contained Cd and 4 out of 52 rice grain samples had Cr concentrations above the Chinese food safety standard pollutant limit (Cd 0.2 mg/kg; Cr 1 mg/kg). Therefore, the PTEs from parent rocks are already threatening rice safety. The government should therefore plan rice cultivation areas accordingly.

The pollution characteristics, sources, and ecological risk of heavy metals in farmland soils were studied in a peak-cluster depression area southeast of Yunnan Province. In total, 199 topsoil samples were collected using the grid method and contents of eight heavy metals (As, Cd, Cr, Cu, Pb, Ni, Zn, and Hg) were determined. The geoaccumulation index and potential ecological risk index (RI) were used to evaluate soil pollution levels and potential ecological risks, respectively. The absolute principal component scores-multivariate linear regression (APCS-MLR) model and cluster analysis were used to identify the pollution sources and apportion the heavy metals in the soils. The results show that the mean content of Cd, Hg, Cr, Ni, and Zn was higher than their respective background values, exceeding them by up to 16.00, 7.29, 1.46, 1.45, and 2.39 times, respectively. No evidence of the occurrence of other metals was found. The average RI was 1039.3, which represents a high potential ecological risk, with Cd and Hg being the most crucial elements. The APCS-MLR model revealed that natural sources (PC1), traffic sources (PC2), fossil fuel combustion sources (PC3), and agricultural sources (PC4) were the four main contributors of soil heavy metals. The primary source of Cd, Cr, and Ni was PC1, while PC2 was the main source of Pb and Zn. PC3 and PC4 were the main sources of Cu and Hg with contribution rates of 77.86% and 70.37%, respectively. The main sources of As were PC1 (46.71%) and PC4 (49.46%).

使用文本挖掘技术分析电子招聘系统大数据职位任职资格和任职要求,以可视化的形式展现大数据技能之间的依赖关系和依赖程度,针对新乡学院大数据专业人才培养方案,提出新的改革方案.在大数据专业课程设置中,要进行数学课程、计算机课程、大数据课程的进一步改革.通过中文分词、词性标注和词序提取大数据职位TOP20技能,利用词向量以及向量矩阵建立技能—技能之间的依赖关系知识库,并以可视化的形式进行直观展现,提出了大数据专业TOP20课程依赖关系,最后对新乡学院大数据专业人才培养方案中的课程体系提出改革建议.

To understand the spatiotemporal variation characteristics and sources of polycyclic aromatic hydrocarbons in karst groundwater in a strongly industrial city, the authors collected 23 groundwater samples in the water and dry period in Liuzhou using component spectra of 16 types of polycyclic aromatic hydrocarbons in combination with the physical and chemical properties and analyzed the spatiotemporal variation characteristics and sources of the polycyclic aromatic hydrocarbons (PAHs) in karst groundwater in heavy industrial city. The results show that the average concentration of ∑PAHs in the groundwater in the wet period has an order of Liubei District > Liudong District > Liuxi District > Jila Underground River and the concentration proportion of PAHs decreases with the increase of the molecular weight, while the order in the dry period is Jila Underground River > Liubei District > Liuxi District > Liudong District. The PAHs in the groundwater during the dry season have a high pollution level, while a low pollution level is observed in the wet season. The main sources of PAHs are organic matter burns at high temperature such as fossil fuel, which are produced by human activities such as industrial processes, transportation, heating, and cooking.

As a heavy industrial city, Liuzhou has been facing a serious pollution problem. It is necessary to take steps to control and prevent environmental pollution wherever possible. Surface soil samples were collected from four communities in Liuzhou City, to determine the concentrations, distributions, sources, and toxicity potential of polycyclic aromatic hydrocarbons (PAHs) present. The mean concentrations of total PAHs in the surface soil are 756.43 ng/g for the heavy industrial area, 605.06 ng/g for the industrial area, 481.24 ng/g for the commercial–cum–residential area, and 49.93 ng/g for the rural area. Both the isomer ratio and principal component analyses for the PAHs prove that these pollutants originate mainly from coal, diesel, gasoline, and natural gas combustion. The pollution hierarchies and toxic equivalency factor of BaP prove that the city is subject to heavy pollution caused by industry, transportation, and daily human activities.

在黔西北不同地区采集地带性和非地带性植物样品和对应的土壤样品,分析了元素在土壤和植物中的含量.结果表明:黔西北自然状态下土壤N、P、K含量低,Ca、Mg元素空间变异较大,微量元素含量大多小于贵州土壤背景值,Co具有明显富集特征,As为区内高背景值元素,Cd污染较严重;盐肤木、鸢尾和马尾松等具有较强的Cd吸收能力,且鸢尾能同时较好地吸收Cd和As;同种植物在不同成土母岩区的元素生物吸收系数差异较大,同种植物在碳酸盐岩区的生物吸收系数要大于碎屑岩区,吸收系数主要受土壤pH和共吸附作用的共同影响.此外,Co和Cd、Cu和Zn的生物吸收系数存在显著相关性,土壤P可能会抑制植物对Cu和Pb的吸收.

In order to determine the pollution of polycyclic aromatic hydrocarbons in the air and atmospheric deposition of heavy industrial city,the air passive sampler and atmospheric wet and dry deposition in Liuzhou Iron and Steel Group co. ,LTD. ,and Shuangchong village,are studied by component spectra of 16 kinds of polycyclic aromatic hydrocarbons,combining with the physical and chemical properties to determine the atmospheric pollution of Liuzhou. The results show that the concentrations of ΣPAHs in the air of Liugang and Shuangchong village are 519. 44,541. 45 ng·d - 1,with an order of 2 - 3 ring > 4 ring > 5 - 6 ring. In rainfall they were 581. 88,756. 09 ng·m - 2·d - 1,and the order is 4 ring > 2 - 3 ring > 5 - 6 ring,in dustfall were 735. 86,1 558. 51 ng·g - 1·d - 1,and the order is 4 ring > 5 - 6 ring > 2 - 3 ring. It is confirmed that the PAHs in atmosphere of Liuzhou come from coal burning by heavy industry enterprises and pollution is serious.

在人工气候箱中,对牡丹品种洛阳红、凤丹白、映金红等3个品种进行不同温度处理,再测定丙二醛含量、脯氨酸含量、可溶性糖含量、超氧化物歧化酶活性,研究高温胁迫对3个牡丹品种生理生化特性的影响.结果发现,40 ℃ 高温胁迫处理后,3个牡丹品种叶片的细胞膜相对透性、脯氨酸含量、可溶性糖含量、丙二醛含量显著高于对照,而净光合速率、可溶性蛋白含量、超氧化物歧化酶活性显著低于对照.结果表明,牡丹植株受伤害的程度与高温胁迫的强度有关,且3个品种的抗热性由大到小顺序为凤丹白>映金红>洛阳红.

In this work,the concentration of metal elements and sediment organic matter (SOM)in sediment cores of the Dashiwei sinkhole section from the Bailang underground river has been studied,and the pollution history of the river basin from 1932 to 2007 has been reconstructed by combining the 210 Pb dating and histori-cal records.The results show that concentrations of main toxic heavy metals Cd and Hg in the sediment cores are high,which are 3.4 and 0.6 times than the soil background values of Guangxi,respectively,even more than 11.2 and 2.7 times of the soil background value throughout China,respectively.On the whole, the distributions of heavy metal elements have a similar increase tendency in the sediment cores.The vertical distribution of metal elements in the sediment cores shows that metal element pollution in the underground river were associated with many events in history,such as peasant movement,the war of Anti-Japanese, Great Leap Forward age,the early stage of reform and opening up ,and the rapid development of economy. Especially,the vertical variation of Ca and Mg in the sediment core records indicates that a new construction climax has begun in this karst mountain area since 1983.Correlation and clustering analyses show that,(1) Cr and Pb came mainly from natural environment,(2)Cu,Ni,Zn,As and MgO originated from natural en-vironment and artificial sources,(3)Cd,Hg,Mn,CaO and SOM stemmed from artificial pollution sources. Correlation analysis with polycyclic aromatic hydrocarbons suggests that part of Zn,Cd and As came from coal combustion.In a nutshell,metal elements in the sediment cores better recorded pollution history of the Bailang underground river.

In order to understand the contamination characteristics of polycyclic aromatic hydrocarbons in different environmental media, the authors collected samples of air, atmospheric dry and wet depositions, soil and groundwater in winter and summer in Nanning, using component spectra of 16 kinds of polycyclic aromatic hydrocarbons, combining with the physical and chemical properties, analyzed concentration, composition and distribution characteristics of the PAHs in different environment media, the results showed that PAHs with 2 to 3 rings were dominant in the air and atmospheric dry and wet depositions, and ∑ PAHs in winter were higher than in summer because of the seasonal differences. And PAHs with 2 to 3 rings were dominant in soil, too. Distribution difference of soil particle diameter was the main reason for the PAHs distribution characteristics in different horizons. And species of PAHs in groundwater were fewer, with lower concentrations, which showed that soil vadose zone could entrap more PAHs. The mass fraction of 16 kinds of polycyclic aromatic hydrocarbons in different environmental media presented a decreasing trend from low rings to high rings, and the distribution characteristics of PAHs with 2 to 3 rings and 5 to 6 rings in different environmental media in two areas in winter and summer had good consistency, but also had certain differences because of the physical and chemical properties of PAHs, hydro-geological conditions, urban pollution, weather conditions, etc.

针对在Shishkin网格上数值求解含有两个参数的奇异摄动问题,在有限差分方法的基础上,将Shishkin网格过渡点参数选取问题转化成一个无约束优化问题,并采用差分进化算法进行求解.数值结果表明用差分进化算法得到最优Shishkin网格参数后,奇异摄动问题的数值解在边界层的精度得到了明显的提高,进一步说明了方法的有效性和可靠性.

为了查清南宁市污染内河对岸边地下水持久性有机污染物的污染规律,选择典型污染河道朝阳溪为研究对象,采取野外水文地质调查与钻探工程手段,采集降雨前、后地下水以及地表水、土壤和沉积物样品测试,分析了污染河道岸边地下水持久性有机物多环芳烃荧蒽、芘和六六六(HCHs)的降雨前、后的污染特征.结果表明,降雨前、后地下水荧蒽和芘多环芳烃的平均浓度分别为24.11、7.98 ng/L;HCHs的平均浓度分别为19.75、13.24 ng/L;朝阳溪地下水有机污染物荧蒽、芘、有机氯农药的检出率和浓度降雨前高于降雨后.有机污染物荧蒽和芘浓度分布随远离朝阳溪的距离增大逐渐升高,而HCHs浓度分布则相反;推测由于物理化学性质的差异,疏水性较强的荧蒽和芘被含水层中悬浮物和河底沉积物强烈吸附,显示近岸未被检出;然而,疏水性较弱的HCHs则有较高浓度,并形成污染源,导致HCHs历史残留源在含水层的“二次释放”.总体上,降雨对地下水中有机污染物有稀释作用,但局部HCHs有扰动释放作用;相关性分析显示地下水中悬浮物浓度与多环芳烃的荧蒽、芘呈中等程度负相关,而与HCHs则呈极强程度正相关,因此含水层中悬浮物对荧葸、芘的“过滤效应”比HCHs要高.朝阳溪岸边地下水中持久性有机污染物的运移影响因素与地下水包气带、含水层结构以及地下水系统补、径、排条件和污染源所处位置密切相关.

In order to reveal the growth and development characteristics and lodging resistance of 42 foxtail millet cultivars(strains) from Henan,Hebei and Shandong provinces,totally 15 traits including days to heading, plant height, panicle length, ear diameter ( represented by ear circumference ) , grain weight per spike,panicle type,lodging index of the first node and so on were identified systematically. The results showed that among the 42 foxtail millet cultivars( strains) ,days to heading ranged from 33 d to 60 d, the shortest days to heading was Longgu 26 ( 33 d ) , followed by 8322-14 ( 36 d ) , the longest days to heading was Jigu 15,K325 and Jigu 29(60 d). Plant height ranged from 43. 72 cm to 81. 19 cm,the lowest was Jigu 28 ( 43 . 72 cm ) , the highest was An 04-4705 ( 81 . 19 cm ) . Panicle length ranged from 7. 71 cm to 16. 33 cm,the shortest was Jigu 28(7. 71 cm),the longest was An 04-5014(16. 33 cm). Ear diameter ranged from 3. 85 cm to 6. 18 cm,the thickest was Jigu 15(6. 18 cm),the finest was Jigu 27 (3. 85 cm). Lodging index ranged from 0. 18 to 0. 82,the strongest was Jigu 22(0. 18),the weakest was 200152. Comprehensively,Yugu 15 and Zheng 05-1 from Henan province,104 and 06-766 from other regions gave better performance with longer panicle,thicker ear,and stronger lodging resistance. Jigu 27 and Longgu 26 gave poorer performance with smaller panicle and weaker lodging resistance.

To trace the source of organic pollution to a natural spring,water samples were collected respectively in rainy season and dry season,and were tapped before,in the middle and after the rainfall process;besides,soil samples around the suspicious contaminated ground were taken simultaneously. Organic pollutants such as HCHs,DDT,fluoranthene,pyrene,benzene and chloroform were analyzed utilizing GC and GC-MS. The tracing investigation indicated that soil samples around two chemical factories and at the places upstream of natural spring showed concentrations of HCHs and polycyclic aromatic hydrocarbons(PAHs)were abnormally high. Meanwhile,HCHs concentration of natural spring water in dry season was 6.0 times higher than that of rainy season,but chloroform concentration in rainy season was higher than that in dry season. As for VOCs including benzene,fluoranthene and pyrene,it was found rainfall in rainy season were conducive to the release of them to infiltrate into groundwater. The vertical distribution of organic pollutants in vadose zone around the contaminated site suggested that their migration behavior were in a pattern of gradually reducing tendency,and were closely related with the factors of TOC,cation exchange capacity and clay particulates as well as their physical and chemical properties. Conclusively,the investigation has traced the sources of organic contamination,i.e. two chemical factories;among the organic pollutants,HCHs and chloroform both maintained sustained releasing status,and PAHs and benzene formed a kind of potential releasing featuring seasonal changes.

For further studying the hydro-chemical characteristics of groundwater,understanding groundwa-ter quality,and revealing the hydrochemical processes that control the evolution of the groundwater quality, we collected 22 sets of pore water and 7 sets of karst water to measue pH,cation and anion,total dissolved solids (TDS)and total hardness,and studied hydrochemical characteristics and formation mechanism.The results show that the average pH of pore water and karst water are both below 7,and the values of TDS and total hardness are almost the same.The most anions in pore water and karst water are both HCO -3 ,with values 68.08 mg/L and 106.68 mg/L,respectively.The cations include Ca2 + ≥Na+ >Mg2 + >K+ ,the aver-age values of Ca2 + are 24.04 mg/L and 31.34 mg/L,respectively.The groundwater hydrochemical composi-tions are formed by the weathered-leached effects and mixing action,groundwater hydro-chemistry type is HCO 3 - Ca type water.The geological environment is a major cause for the generally low pH value of groundwater.The impact of human activity on groundwater is increasingly important.The pH value and change of hydrochemical type are closely related to economic development,population increase,growth of industrial and mining enterprises and other human activity.

通过区间型联系数建立决策模型是解决多属性决策问题,具有方法简单、计算量小的特点,非常契合无线传感器网络资源受限的特点。针对无线传感器网络中路由能量消耗不平衡,提出一种基于区间型联系数的无线传感器网络(wireless sensor network,WSN)路由选择方法,对节点剩余能量、可靠性、方向、邻居节点个数等多属性进行综合评价,利用相对贴近度进行排序选择转发节点,并在属性决策中利用熵权法对多评价目标因子赋权,以避免属性权重选取时的主观性,最终形成路由路径。仿真结果验证了该算法在平衡网络能耗、延长网络生存时间等方面表现出良好的性能。