埇桥环境高风险区河流沿岸土壤重金属污染及生态风险评价

以安徽省宿州市埇桥区奎河、沱河岸边2 000 m范围内的9个村庄作为研究区域,在距离河岸500 m、1 000 m、2 000 m处采集表层土壤样品.使用ICP-MS法检测土壤样品中砷、镉、铬、镍、铅、铜和锌7种重金属的含量,并通过单因子评价法、内梅罗污染指数法及潜在生态风险指数法,评价奎河、沱河周边土壤的污染等级和潜在生态风险.共采集土壤样品27个,砷、镉的超标率为100%(27个),锌超标率37.0%(10个),镍超标率29.6%(8个),铜超标率25.9%(7个),铬超标率22.2%(6个),铅不超标.砷、镉、铬、镍、铜、锌的浓度均超过其背景值.单因子评价结果显示镉为中度污染,砷、铬为轻度污染,其他镍、铅、铜、锌4种重金属属于轻微污染范畴.内梅罗综合污染指数结果显示,奎河、沱河周边土壤综合指数为3.1,属于重度污染.奎河、沱河附近土壤的土壤生态风险值为166.8,该地区生态风险等级为强烈风险.评价结果显示该地区土壤存在一定程度的重金属污染,其生态风险已经超过可接受水平,亟待治理.     

舂陵水衡阳段沉积物重金属污染变化趋势及风险评价

根据2010—2019年舂陵水衡阳段表层沉积物中9种重金属含量,采用地累积指数法及潜在生态危害指数法对沉积物中重金属污染变化趋势及生态风险进行了评价.地累积指数法评价结果表明:沉积物重金属污染程度表现为砷(As)>铜(Cu)>镉(Cd)>锌(Zn)>铅(Pb)>锰(Mn)>汞(Hg)>铬(Cr)>钒(V),As为强污染...     

袁州区表层土壤重金属污染特征及潜在生态风险来源的地理探测

为了探究具有典型的南方丘陵地貌的袁州区表层土壤重金属的空间分布现状、污染程度以及重金属的主要来源,本研究检测该区域162份表层土壤样本中镉(Cd)、汞(Hg)、砷(As)、铅(Pb)、铬(Cr)、铜(Cu)、镍(Ni)、锌(Zn)等8种重金属的含量,运用地统计学、富集因子法、单项污染指数法、潜在生态风险评价法和地理探测...     

渤海湾表层沉积物重金属含量及潜在生态风险评价

海洋沉积物中重金属元素的释放可能影响海水质量及海洋生态健康。于2013年8月采集了渤海湾24个点位的表层沉积物,检测了汞、砷、铜、锌、铅、镉、铬7种重金属的含量,并用Hankanson法分析其潜在生态风险。结果表明,渤海湾沉积物中重金属含量均值可达到国家一类海洋沉积物标准(GB 18668-2002),其中汞、砷、铜、锌、铅、镉、铬的浓度分别达到0.03、16.15、23.15、89.45、38.84、0.24和60.60 mg·kg-1。渤海湾不同点位中,表层沉积物重金属含量符合海洋沉积物质量一类标准的占83.3%,其余点位可满足二类标准,超一类标准的点位的主要超标因子是砷和铅。渤海湾重金属的综合生态风险指数达到95.01,属于轻微生态风险等级。不同重金属所产生的生态风险排序为镉汞砷铅铜铬锌,除镉外均属于轻微生态风险等级。镉的潜在生态风险值为47.00,达到了中等生态风险等级,其风险占所有重金属总风险的49.5%。镉的潜在生态风险高与镉的生物毒性较高及其近年来在渤海沉积物中积累速度较快有关。重金属潜在生态风险在河口地区和天津港工业区附近呈现高值,而南部渔业区和远离海岸的中心区的生态风险相对较低,说明近海工业活动和陆源污染排放渤海湾沉积物中的重金属生态风险的主要来源。因而,调整近海的产业结构,严格控制入海河流和近海经济活动的重金属特别是镉的污染排放,对保障渤海沉积物的生态安全至关重要。     

芜湖市龙窝湖湿地土壤重金属污染特征及潜在生态风险评价

分析了不同人类活动方式下芜湖市龙窝湖湿地土壤镍（Ni）、铬（Cr）、镉（Cd）、铅（Pb）、铜（Cu）和锌（Zn）含量差异,采用污染指数法、潜在生态风险指数法和沉积物质量基准（SQG）比较法对湿地土壤重金属污染特征和潜在生态风险进行评价。结果表明：6个样地土壤重金属含量只有Cd含量（0．76—3．67mg／kg）显著超过土壤环境质量二级标准（GB15618—1995）;6个样地土壤Cd和Cu含量与塘式水产养殖湿地、网式水产养殖湿地、垃圾倾倒地下游湿地和垃圾倾倒地土壤Pb和Zn含量超过土壤背景值,而6个样地土壤Ni和Cr含量与湖泊底泥和耕地土壤Ph和Zn含量未超标;土壤6种重金属综合污染指数为垃圾倾倒地下游湿地（25．4）〉网式水产养殖湿地（25．3）〉塘式水产养殖湿地（23．1）〉垃圾倾倒地（19．2）〉耕地（8．2）=湖泊底泥（8．2）;土壤6种重金属综合潜在生态风险指数为网式水产养殖湿地（603．6）〉垃圾倾倒地下游湿地（595．5）〉塘式水产养殖湿地（538．4）〉垃圾倾倒地（439．9）〉耕地（145．6）〉湖泊底泥（136．6）。土壤cd含量高是导致湿地土壤重金属较高污染（Cd单项污染指数占综合污染指数：49％～76％）和存在严重潜在生态风险（Cd单项潜在生态风险指数占综合潜在生态风险指数：88％～96％）的关键元素。基于沉积物质量基准比较法的潜在风险评价结果表明湿地土壤存在M、Cd和Cu污染的中等潜在生态风险。     

浙江中部经济发达区域流域重金属污染调查与分析

为了解浙江中部经济发达区域流域重金属的污染情况.以东阳市东阳江流域为例,采集该流域37条干支流在丰水期和枯水期的水样,并对典型重金属锌、铜、铅、铬、镉、砷和汞含量进行测定及评价.结果表明:(1)东阳江流域干支流在丰水期和枯水期重金属平均含量排序均为:锌铅铜铬砷镉汞,其中锌、铜和镉含量均未超过地表水Ⅲ类标准,其他重金属均超标且超标率排序为:汞铅铬砷;(2)东阳江上游支流到下游支流的锌、镉、汞变化趋势呈现波峰和波谷交替出现的势态,高峰值出现在东阳市工业园区与经济强镇;(3)内梅罗污染指数指数评价得出,柽溪和绕溪在丰水期和枯水期均达到中度重金属污染水平;(4)健康风险评价法表明,化学致癌物引起的健康风险水平远远大于非致癌物引起的健康风险水平,通过饮水途径引起的健康风险水平大于皮肤接触,该流域致癌物的健康危害顺序:铬砷镉.     

辽东湾河口底泥中重金属的污染评价

通过对辽东湾诸河口底泥中铅、锌、铜、镉等的分析,发现辽东湾底泥中的重金属污染物主要是Cd,Zn,Pb,其中,Cd平均含量为1.155mg·kg-1,超过土壤环境质量三级标准,Zn平均含量为105.277mg·kg-1,超过土壤环境质量一级标准.运用地累积指数法及潜在生态风险指数法对其污染程度进行评价,认为辽东湾西北及北部河口底质污染严重,葫芦岛市五里河桥下＞大凌河口北＞辽河口＞双台子河口等处.与历史资料相比,4种重金属的平均含量均有显著提高.     

秦岭典型停产关闭锌冶炼企业场地土壤重金属污染特征研究

秦岭作为中国重要的生态屏障,其生态环境保护问题已上升为国家战略。同时,秦岭作为中国贵金属和多金属矿产资源富集区,矿业开采效益巨大。矿山开采和冶炼不可避免带来一定的环境问题,研究矿业生产过程中土壤重金属污染污染特征及其危害对秦岭地区土壤重金属污染修复意义重大。该研究以秦岭地区某一曾从事过燃煤发电和锌冶炼、目前已停产的工业企业场地为研究对象,对土壤中砷、镉、铜、铅、汞、镍和锌7种重金属进行测定,采用Muller地积累指数、潜在生态风险指数和空间分析等方法,对土壤中的重金属元素进行污染特征分析与评价。结果表明,7种重金属在土壤中均有检出,砷、镉、汞、锌的检出最大值为对应土壤污染风险筛选值的1.54、1.29、1.49、2.45倍;在空间上7种重金属浓度均表现出由生产区向四周衰减趋势,砷、铜、铅和锌在土壤表层和深层污染程度表现不均一,镍基本无污染;镉和汞的地累计均值分别为5.72(陕西省)、5.715(国家)和6.74(陕西省)、6.71(国家),潜在生态风险指数分别为2 376.55(陕西省)、2 367.20(国家)和6 400.45(陕西省)、3 148.30(国家),属于严重污染等级且危害程度极强;将所有重金属元素指数累加,生态危害风险级别达到D,该场地生态危害程度极强,需进行严格管控及治理。该研究可为秦岭地区同类型企业土壤重金属污染监测方案的制定提供借鉴,也为构建秦岭区域矿山土壤重金属污染防控体系提供技术支撑。     

湖南典型金属冶炼与采选行业企业周边土壤重金属污染评价及源解析

为了解湖南省典型金属冶炼与采选行业周边土壤重金属污染现状.以30家金属冶炼与采选行业周边表层土壤为研究对象,采用单因子污染指数、内梅罗污染指数、潜在生态风险指数及《农用地土壤污染风险管控标准》(GB15618-2018)评价了土壤镉(Cd)、汞(Hg)、砷(As)、铅(Pb)、铬(Cr6+)、铜(Cu)、镍(Ni)、锌...     

伊犁煤矿土壤重金属累积对土壤酶活性的影响

本文以伊犁地区的庆华煤矿、铁厂沟煤矿和达达木图煤矿为研究区,对矿区周边土壤4个土壤深度0—10 cm、10—20 cm、20—30 cm、30—40 cm的重金属全量(铜、锌、铅、镉、铬、镍)和土壤酶活性(脲酶、蔗糖酶、过氧化氢酶)进行分析,结果表明:(1)3个矿区中,重金属铜的含量为21.72—31.85 mg·kg~(-1),是国家土壤背景值的0.6—0.9倍;重金属锌的含量为79.28—114.94 mg·kg~(-1),是国家土壤背景值的0.8—1.1倍;重金属铅的含量为44.39—60.19 mg·kg~(-1),是国家土壤背景值的1.7—2.3倍;重金属镉的含量为0.54—2.33 mg·kg~(-1),是国家土壤背景值的0.9—3.9倍,重金属铬的含量为27.71—48.08 mg·kg~(-1),是国家土壤背景值的0.4—0.8倍;重金属镍的含量为9.25—18.07 mg·kg~(-1),是国家土壤背景值的0.15—0.3倍;(2)铜、锌、铬、镍、铅与脲酶活性呈显著相关(P0.01),相关系数分别为-0.391,-0.547,-0.502,-0.656,0.477,铜、锌、铬、镍、铅与过氧化氢酶活性呈显著相关(P0.01),相关系数分别为-0.384,-0.563,-0.559,-0.693,0.447,这表明过氧化氢酶活性和脲酶活性可以反映重金属铜、锌、铬、镍、铅5种重金属元素的污染程度;蔗糖酶活性与锌、铬、镍、铅呈显著相关(P0.05),相关性系数分别为-0.359,-0.404,-0.371,0.312,这表明蔗糖酶活性能反映锌、铬、镍、铅4种重金属元素的污染程度.     

On the behaviour of the residence time at the bottom of the mixed layer

To understand why the findings of Deleersnijder et al. [(2006), Environ Fluid Mech 6: 25–42]—the residence time in the mixed layer in not necessarily zero at the pycnocline—are consistent with those of Delhez and Deleersnijder [(2006), Ocean Dyn 56:139–150]—the residence time in a control domain vanishes at the open boundaries of this control domain—, it is necessary to consider a control domain that includes part of the pycnocline, in which the eddy diffusivity is assumed to be zero. Then, depending on the behaviour of the eddy diffusivity near the bottom of the mixed layer, the residence time may be seen to exhibit a discontinuity at the interface between the mixed layer and the pycnocline. If such a discontinuity exists, the residence time is non-zero in the former and zero in the latter. This is illustrated by analytical solutions obtained under the assumption that the eddy diffusivity is constant in the mixed layer.     

Adjusting the economy to the new energy realities of the second half of the age of oil

Our research indicates that, due to the depletion of conventional, and hence cheap, crude oil supplies (i.e. peak oil), increasing the supply of oil in the future would require exploiting lower quality resources (i.e. expensive), and thus will most likely occur only at high prices. This situation creates a system of feedbacks where economic growth, which requires more oil, would require high oil prices that will undermine that economic growth. We conclude that the economic growth of the past 40 years is unlikely to continue unless there is some remarkable change in how we manage our economy.     

豪猪消化系统的解剖研究

为了了解豪猪的消化生理,为豪猪的人工饲养技术研究提供基础依据,以达到高效饲养豪猪的目的,笔者对豪猪的消化器官进行了系统解剖研究.结果表明:豪猪的胃为单室胃.盲肠很发达,这与其能够消化植物纤维有关.豪猪肝脏很发达,其重量为402 g,是其体重的4.59%,肝脏分叶多而明显.     

刍议医院资产管理的现状及其对策

医院的固定资产和流动资产是医院赖以生存和发展的基础,是一项非经营性国有资产．目前公立医院固定资产、流动资产管理现状不容乐观,针对这种状况,首先分析问题形成的原因,然后提出管理的措施或建议,从而使资产管理工作规范化、制度化、科学化,使有限的卫生资源发挥出最大的社会效益和经济效益．参3．     

Observations on the function of the glands of the foot of the pediveliger of Ostrea edulis during settlement

The use during settlement of secretions of the 9 different types of gland in the foot of the pediveliger of Ostrea edulis L. was examined experimentally. During settlement, there is a progressive decrease in the crawling speed of the larva and a strengthening of its bond with the substratum. Both changes are related to (a) a change from ciliary to muscular pedal locomotion; (b) the increasing acidity and viscosity of the mucoid secretions used; (c) the secretion of a byssus thread by the glands of the byssus duet; (d) changes in the form and composition of this byssus. At the termination of settlement, the entire contents of 2 types of gland are discharged. Their secretions give rise to the cement which permanently fixes the larva to the substratum. The 9 types of gland are utilised sequentially in a manner closely related to the 6 phases recognised in settlement behaviour.     

Mining of the forest and the time path of the price of timber

The paper analyzes the effect of transportation (site specific) costs and the effect of mining (depletion) of the forest on the time path of the price and of the net price of timber in two forestry models. The models differ in that one has zero costs and the other has positive costs. The analyses yield the standard mining theory results for certain cases. They also yield extentions of these results for cases with growth of the harvested trees and/or regeneration on the harvested land. The paper concludes, as one would expect, that the theory of the mine is useful in analyzing the time path of the price of timber.     

The impact of the Jonglei Canal on the economy of the local people

The idea of saving the water lost in the ‘Sudd’ swamp through evaporation was conceived by Egypt and Sudan for their own interests, but not for those of the Nilotic peoples living in the flood plain. Concern for the local development was only taken into consideration after the 1974 Juba riots, when three people were killed and 200 arrested. The canal has caused displacement of people from their settlements and is blocking the seasonal movement of livestock and wildlife. Conflict may arise over the use of land for grazing or irrigation. The Nilotics are concerned about the possible negative environmental impact, and the loss of their cultural identity. They maintain that Egypt should pay them monetary compensation for the disruption that the canal has caused to their livelihood.

This paper assesses the impact that the Jonglei canal project will have on the economy of the Nilotics; traces the historical development of the project; outlines the social, political and economic organization of the Nilotics; and assesses the impact the project will have on the local population. The paper concludes by casting doubt on the benefits the canal will bring to the Nilotics.     

浅谈校园网ARP欺骗攻击与防御

ARP欺骗木马病毒是校园网络中经常出现的病毒攻击形式．基于ARP协议的概念和工作原理,并通过分析ARP欺骗的工作原理,提出了几种可行的解决ARP欺骗攻击的实用方法,以达到防范并解决ARP欺骗的目的．参5．     

三峡库区消落带土壤中铅污染调查

报道了三峡库区长江干流及小江支流消落带土壤中重金属铅含量背景值的调查结果。结果表明,目前土壤未被重金属铅污染。