Heavy metal pollution in tidal zones of Bohai Bay using the dated sediment cores

Three sediment cores were collected in November 2003 from Dagu estuary to Qikou estuary. The main polluted heavy metals in the sediment of tidal zones for the Bohai Bay have been found by analyzing the relationship among the contents of heavy metals, the contents of geochemical elements （Fe, AI and Mn） and the size of grain. The dominating contaminative elements in tidal sediments of Bohai Bay are Pb, Zn and Cd. Their contents are higher than the corresponding upper limit of environmental background values and they have very faint correlation with the corresponding contents of geochemical elements and the size of grain, indicating the anthropogenic enrichment. Especially, the preliminary study on the pollution sources and the history of heavy metals in the Dagu estuary has been done using the dated results. The contamination by Zn and Cd also started in the middle 1950s, while the contamination by Pb appeared in the early 1940s. The pollution by Zn and Cd mainly originate from sewage discharge, while the pollution by Pb has many sources, like atmosphere deposition and industrial discharRe.

A Numerical Computation Method for Current Field in Tidal zone

In this paper, a numerical computation method is developed for the computation of current field in the tidal zone, using the well-point method and ADI method. The computational results agree well with the general variation of current field in the tidal zone.

Tidal Flushing Time of Marine Fish Culture Zones in Hong Kong

Accurate determination of flushing time is crucial for maintaining sustainable production in fish culture zones （FCZs）, as it represents the physical self-purification capability via tidal exchange with clean water in the outer sea. However, owing to the temporal and spatial complexity of the coastal flushing process, existing methods for determining flushing time may not be generally applicable. In this paper, a systematic method for determining the flushing time in FCZs is presented, in which bathymetry, runoff, tidal range and stratification are properly accounted for. We determine the flushing time via numerical tracer experiments, using robust 3D hydrodynamic and mass transport models. For FCZs located in sheltered and land-locked tidal inlets, the system boundary can be naturally defined at the connection with the open sea. For FCZs located in open＇waters, hydrodynamic tracking is first used to assess the extent of tidal excursion and thus delimit the initial boundary between clean water and polluted water. This general method is applied to all designated marine FCZs in Hong Kong for both the dry and wet seasons, including 20 sheltered FCZs （in semi-enclosed waters of Tolo Harbour, Mirs Bay, and Port Shelter） and 6 FCZs in open waters. Our results show that flushing time is the longest in inner Port Shelter （about 40 days in dry season）, and the shortest for the FCZs in open waters （less than one week in dry season）. In addition, the flushing time in dry season is commonly longer than that in wet season： 20%~40% for most well-sheltered FCZs; 2.6-4 times for the others. Our results indicate a positive correlation between the flushing time and distance to open boundary, supporting the view that the flushing time of a FCZ is closely related to its location. This study provides a solid basis for mariculture management such as the determination of carrying capacity of FCZs.

Some Aspects of the Diurnal and Semidiurnal Tidal Wind Field in Meteor Zone

The diurnal and semidiurnal tidal wind field variations in the altitudes between 80 and 100 km of the earth's atmosphere over a mid-latitude station are studied by means of the phases of the zonal and meridional wind measurements made at Atlanta (34 ° N, 84 ° W). The rotation of diurnal tidal wind vector is seen to be clockwise at lower heights (80-86 km), swinging between clockwise and anti-clockwise at intermediate heights (88-96 km) and anti-clockwise at higher heights (96-100 km). The senses of rotation of diurnal and semidiurnal tidal wind vectors are compared between the stations located in the same and opposite hemispheres. The results are consistent with the tidal theory in the case of Atlanta and Adelaide (35°S, 139 ° E) whereas in the case of other stations considered in the present study, they showed marked variations.

A Statistical Analysis on Recent Tidal Triggering of the Earthquake in the Tianshan Seismic Zone

A statistical analysis is done to study the spatio-temporai features of earthquake activity in the Tianshan seismic belt triggered by tide, based on Schuster＇s test. The data we choose is the ML ≥2. 0 earthquakes from January 1, 2010 to August 31, 2012 in eastern Tianshan, and the calculation is on tidal body stress. The results show that the p-value based on the time window smoothing of Schuster＇s test corresponds better with the strong earthquakes in the Tianshan seismic belt, especially for a long time before the November 1, 2011 Nilka Ms6. 0 earthquake, when the p-value of the Schuster＇s test was always lower than the threshold of 0. 05 for tidal trigger of earthquake, but after the Niika Ms6. 0 earthquake, that value was quickly restored to a high level, which reflects a close relationship between the Nilka Ms6. 0 earthquake and the Earth tide. According to the p-value based on the spatial window smoothing of Schuster＇s test, the Nilka Ms6. 0 earthquake was at or near the tidal triggering area. Thus we can see from the spatio-temporal results that the Nilka Ms6. 0 earthquake was obviously triggered by Earth fide.

潮汐波动带偏载超深基坑变形控制数值模拟分析及工程实践

随着我国地下空间的持续开发,穿江越河及邻江邻河的地下工程项目越来越多,这类项目往往伴随邻山且邻水的工程特定环境,其深基坑工程变形机制和影响效力尚不明确,相关控制手段亦少有研究。依托杭州市某紧邻钱塘江的市政隧道工程,考虑潮汐波动影响对36.4m超深大偏载基坑变形进行了三维数值模拟分析,提出相应变形控制方法并进行工程实践。研究表明:通过依托工程基坑内外水位监测数据的理论分析和数值求解,建立基坑渗流场时空演化模型,得知潮汐水流进入土层边界时的水头衰减较大,在渗流路径中,水头变化较稳定,基坑附近地下水对潮汐循环荷载的响应有明显滞后性,基坑周围产生较高孔隙水压力。运用有限元软件采用修正Mohr-Coulomb弹塑性本构模型,建立偏载深基坑开挖及周围环境影响的数值模拟三维模型,为模拟潮汐波动带的影响,简化在基坑河流底部分别施加25kPa和65kPa均布荷载,得出相较于普通环境,潮汐动力影响下的基坑变形控制更应引起重视,通过三维数值模拟及工程实践,验证了超深基坑采用“1 200mm地下连续墙+5道混凝土支撑+2道钢支撑”的联合支护形式是一种有效的临近钱塘江超深基坑的支护对策。

Heavy metals in suspended matters during a tidal cycle in the turbidity maximum around the Changjiang(Yangtze) Estuary

In order to discuss the content distributions and fluxes of heavy metals in suspended matters during a tidal cycle in the turbidity maximum around the Changjiang （Yangtze） Estuary, the contents of heavy metals （Zn, Pb, Cd, Co and Ni） have been analyzed. During a tidal cycle, the average contents of heavy metals are in the order of Zn〉Ni〉Pb〉Co〉〉Cd. The average contents in ebb tide are generally higher than that in flood tide. However, at the inshore Sta. 11, influenced by the contamination from the nearby waste treatment plant, the average contents of Zn and Ni in flood tide are higher than those in ebb fide and at the offshore Sta. 10, the content of Cd in flood tide higher than that in ebb tide due to marine-derived materials. The five heavy metals, mainly terrigenous, are transported towards east-northeast, and settle down with suspended matters in the area between Sta. 11 and Sta. 10. Influenced by marine-derived materials, the flux value of Cd does not alter significantly with obviously changing in flux direction towards northwest. The source of heavy metals, the salinity of water and the concentration of suspended matters are the main factors controlling the content distributions of heavy metals during a tidal cycle. There is a positive correlation between the contents of heavy metals （Zn, Pb, Co and Ni） and the salinity of water, while the opposite correlation between the contents and the concentrations of suspended matters. Because of marine-derived materials, the content of Cd is not correlated with the concentration of suspended matters and the salinity of water.

Study on Peat-Forming Mechanism of Tropic and Sub-TropicTidal Flats

Tropic and sub-tropic tidal flats (generalised) are a kind of speific peat-forming environments. Taking the Mangrove tidal flats and mangrove pets in Hainan island as a example, the authors deeply study and discuss the peat-forming mechanism of tropic and sub-tropic tidal flats. The conclusions are as follows: intrusion accretiou of plant organic matter is more important ; the organic matter has accumulated witk high productivity, high return rate and high decompeition rate ;anaerobic bacterin play a more important role during early peatification ; sea level change is the fundameutal factor controlling the formation and evolution of tidal flat peat-forming environments; lagoon peat-flat and delta peat-flat are main types of tidal flat peat-forming euvironments ;tidal flat peat-forming environments are remarkably characterized by low-level and rabe properties.

电连接对Q235碳钢在海洋环境中跨区带腐蚀行为的影响

通过对腐蚀速率、微观形貌和锈层成分的测试与分析,研究了电连接状态对Q235碳钢在青岛实海环境中跨越全浸区和潮差区腐蚀行为的影响。结果表明:在非电连接状态下,全浸区试样的腐蚀速率低于潮差区,潮差区试样的腐蚀速率随着暴露高度的增加而增大;在电连接状态下,处于最低潮位线下方试样的腐蚀速率出现峰值,而在潮差区,处于中潮位区域试样的腐蚀速率出现最低值;在全浸区上部和整个潮差区试样的腐蚀形貌存在明显差异;在两种状态下潮差区试样表面锈层成分存在明显差异,在电连接状态下存在锈层的影响,随着暴露高度的增加,锈层中Ca和Mg含量逐渐增加。

江苏滩涂海岸带生态承载力空间异质性研究

文章选择拥有独特的淤泥质海岸带与丰富多样的滩涂湿地生态系统,并且兼具较好发展优势和潜力的江苏沿海地区为研究区,选取湿地、林地、重点功能区、入海河流水质、土壤5个承载力指数,构建能够表征沿海生态承载能力的评价体系,运用GIS等空间技术,以南通、盐城、连云港三市的区县及网格等组成评价单元,通过计算单项指数与多项指数综合评价生态承载力,分析沿海地区生态承载适宜性的空间格局异质性,揭示造成空间生态承载状态差异的影响因素。结果表明:研究区“适宜”、“较适宜”、“一般适宜”、“控制”、“不适宜”5个生态承载等级分别占研究区总面积的16.59%、11.22%、38.50%、17.15%、16.54%;承载力在空间格局上存在显著异质性,呈现“中间低,南北两头高”的分布特点,南部南通地区承载力相对高于北部连云港地区,主要为“适宜”和“较适宜”分布区,中部盐城地区生态承载力明显低于其他地区,主要为“不适宜”和“控制”分布区。

辽河坳陷东部滩海深层—超深层天然气勘探重大发现及意义

随着勘探开发程度的日益提高,“深层—超深层能否突破”已成为制约中国东部老油区稳定发展的重要科学问题。矿权面积较小的辽河油田该问题尤其突出,对于湖盆狭长、资料品质较差的辽河坳陷深层难度极大。通过区域构造演化分析及生烃、成藏两大动力学研究,明确了辽河坳陷东部滩海成盆、成烃、成藏机制。原始湖盆为箕状结构,受其控制主力烃源岩具有“深、大、广”分布特征;深层发育干酪根热解、原油裂解两种成因的成熟—高成熟天然气,资源潜力大;沉积充填序列中的多套泥质岩类与早期走滑剪切断层双因素耦合造就深层—超深层为独立的“流体封存箱”,具有自生自储、旁生侧储两种运聚方式的成藏模式,具备大中型天然气田形成的有利地质条件。风险探井葵探1井取得勘探重大突破,对进一步深化辽河坳陷乃至断陷盆地深层—超深层油气勘探具有重大实践和成藏理论指导意义。

渤海湾南部滩涂贝类群落结构特征及其环境因子相关性研究

本研究以渤海湾南部(滨州)滩涂为研究区域,设置6个断面共36个采样站位,覆盖潮间带(高潮带-中潮带-低潮带)和潮下带,研究该区域贝类资源群落结构特征及其环境因子相关性。结果表明:整个调查区域常见贝类总共有30种。潮间带共有23种常见贝类,优势种为光滑篮蛤(Potamocorbula laevis Hinds 1843)、四角蛤蜊(Mactra quadrangularis Reeve 1854)、短文蛤(Meretrix petechialis Lamarck 1799);潮下带共有26种常见贝类,优势种为中国蛤蜊(Mactra chinensisi Philippi 1846)、等边浅蛤(Gomphina aequilatera Sowerby 1825)、朝鲜笋螺(Terebra koreana Yoo 1976)、红带织纹螺(Nassarius succinctus A.Adams 1852)、纵肋织纹螺(Nassarius variciferus A.Adams 1851);潮间带贝类多样性指数(H')和均匀度指数(J')显著高于潮下带,而丰富度指数(D)则相反;潮间带贝类生物量(710.16 g/m^(2))和栖息密度(4523个/m^(2))远高于潮下带(17.10 g/m^(2),35个/m^(2))。群落结构多元统计分析将贝类按照站位划分为5个组群,包括东侧潮下带、西侧潮下带、西侧潮间带、东侧潮间带以及D4站位。冗余分析(RDA)结果表明,对潮间带贝类影响较大的环境因子主要为沉积物的粒径以及砂、粉砂含量,而对潮下带贝类影响较大的主要为浮游植物密度、沉积物的粒径以及砂、粉砂和黏土含量。渤海湾南部(滨州)滩涂贝类资源较为丰富,但应从不同滩涂区域生态特性的角度出发,加强贝类的保护和资源修复,本研究可为该区域贝类的资源养护和可持续利用提供数据基础。

辽河口潮滩潮沟形态特征与水文连通强度评价

为了解潮沟形态的空间变化特征,以辽河口潮滩为例,基于潮位校正原理精确划分潮区,采用半自动方法提取精细化线状潮沟图像,基于潮沟分级算法对潮滩潮沟进行分级,定量分析潮沟的形态特征参数,并对潮滩上潮沟网络连通度进行定性评价。结果表明:潮沟的级别与平均长度具有明显的空间异质性,随着潮沟级别增加,研究区域潮沟平均长度呈指数上升,潮沟数量呈指数下降(R 2>0.99);随着潮滩高程逐渐降低,潮沟总密度显著减小,随着潮沟级别增加,潮沟密度与频数均大幅下降;潮滩距离外海愈近,潮沟曲率愈低,高潮滩潮沟分汊率最高(Rb=3.54),潮沟最不稳定;辽河口潮沟网络连通度与潮沟总分汊率、环岛潮沟数量呈正相关,潮沟网络发育程度则主要由潮沟曲率和支潮沟的密度决定,其中,高潮滩潮沟网络水文连通度最好,潮上带潮沟网络发育程度及排水效率最高。研究表明,潮汐水动力对辽河口潮沟形态特征演变及水文连通强度影响较大,进一步加强辽河口潮沟网络的排水效率可有效缓解辽河口潮滩湿地退化进程,实现盐沼植被的生态修复。

海砂海水混凝土圆柱体抗压强度试验研究

设计了36个海砂海水混凝土试件(18个立方体与18个圆柱体)进行轴压加载试验,考虑了水灰比和海洋潮汐区浸泡龄期对其抗压强度的影响。观察了试件的受压破坏过程与形态,获取了重要力学性能指标,分析了各参数对其力学性能指标的影响规律,结果表明:海砂海水混凝土试件破坏形态表现为黏结开裂破坏和骨料开裂破坏;随着水灰比的减小,海砂海水混凝土立方体抗压强度和圆柱体抗压强度均逐渐增大;浸泡龄期(T<270 d)对海砂海水混凝土立方体抗压强度和圆柱体抗压强度的影响规律不显著。

1989—2021年中国大陆海岸带潮滩、海岸线、养殖水体遥感观测

海岸带是世界上容纳人口最多的区域,其生态系统受到人类活动的强烈影响。潮滩、海岸线、养殖水体变化是海岸带生态系统健康监测的重要要素。由于潮汐作用,海陆水边线处于动态变化状态,是应用遥感技术进行潮滩、海岸线检测的主要难点,故通过综合Landsat4/5/7/8和Sentinel-2A/B卫星遥感数据对1989—2021年间中国大陆海岸带潮滩、海岸线、养殖水体进行了7期监测,发挥了多源卫星观测频次高的优势,通过检测不同潮位的水边线实现潮滩、海岸线、养殖水体的识别。结果表明:针对不同水色的海水应选用不同的水体指数组合,对于清澈或低浑浊度的海水,应分别采用修正的水体指数(modified normalized difference water index,mNDWI)与归一化差值水体指数(normalized difference water index,NDWI)检测高潮位、低潮位水边线,有效提高潮滩检测的可靠性,检测的潮滩面积比通常仅用mNDWI指数检测的潮滩面积大122%;对于高浑浊度海水(浙江省、江苏省和上海市),应采用mNDWI进行高潮位、低潮位水边线的检测,以避免NDWI将高浑浊度海水误识别为潮滩,对养殖水体应采用NDWI检测。1989—2021年,中国大陆海岸带发生了巨大变化,潮滩快速消失,养殖水体面积和海岸线长度增加,整个中国大陆海岸带的潮滩减少率、海岸线长度和养殖水体增加率平均分别为46.2%,34.4%和149.3%,潮滩面积减少了7173.2 km^(2),海岸线长度增加5320.5 km,养殖水体面积增加了9046.5 km^(2)。北方省份或城市遭受的潮滩损失比南方省份或城市更严重。以1989—2021年潮滩平均减少率计算,辽宁省、河北省和天津市、山东省的潮滩将分别在27 a,10 a和22 a内完全消失。潮滩和养殖水体的面积变化高度负相关,表明养殖水体的扩展是潮滩减少的重要驱动因素。

潮间带地热田水化学特征及成因机制分析

广东省江门台山汶村潮间带地热田地热资源储量丰富,研究其水化学特点、成因机制和热储温度可为后续开发利用提供参考。通过Piper三线图分析地热水水化学特点,根据代表组分离子比例系数和其日变化、年变化规律分析地热水成因机制;通过氢氧同位素分析并定量估算丰水期与枯水期地热水中咸水-淡水混合比例;利用Na-K-Mg三角图和地热温标公式法估算地热田热储温度。结果表明:研究区地热水属海相沉积地热水,热储温度约150℃,为深部热源沿断层上升过程中受浅表淡水和海水混合作用的结果,丰水期和枯水期的淡水比例分别为77.60%和58.76%。

天津港南疆港区半圆型防波堤耐久性试验研究

为了探究天津港南疆港区N5区半圆型防波堤耐久性,通过现场勘查半圆型防波堤破损状态、力学性能检测、孔溶液pH值检测、芯样氯离子含量检测以及混凝土断面微结构SEM分析等手段,结论如下:①浪溅区芯样抗压强度、混凝土孔溶液pH均小于潮差区;②潮差区水溶性氯离子含量大于浪溅区,预估潮差区、浪溅区剩余服役年限分别为32 a、30 a;③断面微结构密实度由大到小依次为试验室龄期180 d混凝土、潮差区混凝土、浪溅区混凝土。上述研究结论为海洋环境下钢筋混凝土结构长期服役过程中劣化原因提供了理论分析以及为类似工程施工设计、质量控制提供指导性科学依据。

渤海湾天津段潮间带沉积物柱状样重金属污染特征

2003-11采集了渤海湾天津段北至大沽口,南到岐口海域潮间带3个沉积物柱状样,对沉积物的粒度、有机质、重金属含量进行分析,对渤海湾潮间带沉积物柱状样的地化性质、重金属污染概况以及重金属的空间、垂向分布特点进行了研究.渤海湾潮间带沉积物由北至南逐渐变细,大沽口和独流减河口海域的沉积物主要是极细砂-粉砂-细砂组成,岐口海域潮间带沉积物主要组分是粉砂和极细砂.3个柱状样的垂向粒度分布趋势表明渤海湾潮间带沉积物自下向上有“粗化”的趋势.Fe、Al、Mn3种元素的空间分布与沉积物的粒径呈显著的负相关性,即Fe、Al、Mn含量主要分布在粒度较细的沉积物中.渤海湾潮间带主要重金属污染元素是Pb、Zn、Cd 3种.通过归一化研究,这3类重金属元素在沉积物中有很明显的人为污染痕迹,含量远远高于其相应的环境背景值.

混凝土使用寿命预测方法的研究Ⅱ——模型验证与应用

借助于大量的实验数据,对文献[1]建立的混凝土氯离子扩散理论模型进行了实验验证和工程验证。结果表明,在海洋氯离子环境中混凝土结构的氯离子浓度实测值与本文理论模型预测值完全相符,取得了满意的验证效果。此外,依据氯离子扩散理论模型确定了混凝土的氯离子扩散系数、渗透性与其使用寿命的关系,探讨了高性能混凝土在恶劣条件下的最大水胶比和最小保护层厚度等耐久性设计参数,与瑞典高性能混凝土手册的规定基本一致。

盐度对稀释平板法研究红树林区土壤微生物数量的影响(英文)

在使用稀释平板法分离潮间带红树林及其对照光滩土壤微生物以及计数时,多数情况下使用陈海水制作培养基和稀释水,很少考虑培养基和稀释水的盐度对最终计数结果的影响。使用稀释平板法研究了盐度对福建九龙江口红树林区与深圳福田红树林保护区土壤微生物平板计数的影响,结果表明培养基与稀释水盐度对微生物数量有明显的影响。统计分析显示细菌的海水稀释效果优于淡水,而放线菌与真菌则刚好相反（P〈0.05,一个例外）。海水不适合配制红树林区土壤微生物平板计数的培养基,从0-35,高盐度的平板培养基会降低微生物的数量,尤其是放线菌的数量,尽管培养基的盐度对真菌影响无规律,但细菌数量在低盐度时比在高盐度和不加氯化钠时要多。根据盐度效应,提出了稀释平板技术应用于潮间带的红树林及其相应光滩时的优化方法,认为细菌应该用海水作无菌稀释水,而放线菌和真菌则应用淡水作稀释水;包括光滩在内的红树林区土壤微生物分离与计数的培养基宜控制较低盐度范围。