天津沿海排污河中稀土元素的地球化学特征

选择天津沿海的南、北排污河为对象，研究了城市排污河中稀土元素的某些地球化学特征。结果表明，在排污河水体中溶解态稀土含量仍很低，但与其他天然大河相比，Eu和重稀土溶解态含量明显偏高。原水中稀土元素含量较高，以悬浮态为主。轻稀土的溶解态与悬浮态分布模式随原子序递增有相反的变化趋势。沉积物与悬浮物中的稀土含量明显低于其他天然河流，而悬浮物中的稀土含量又明显低于沉积物。沉积物与悬浮物中的稀土分布模式相似，均为轻稀土富集、重稀土亏损、Eu正异常型。这种分布模式与其他天然河流不同，而与本地区含有机质丰富的土壤相似，表明其外源为附近土壤。排污河稀土元素地球化学特性与天然河流的差异可能主要由于其水体中含有大量有机污染物造成的。     

太湖水体中稀土元素地球化学特征

以中国第三大淡水湖泊太湖为研究对象,通过液-液萃取、连续提取法以及ICP-MS测试技术对太湖水体中溶解态和悬浮物中的稀土进行分析.结果表明:太湖水体中溶解态稀土含量较低.由于湖水的混合作用整个西太湖水体中稀土元素含量比较相近,东太湖水体由于自净化作用含量低于西太湖.由于颗粒物表层胶体的吸附作用,溶解态稀土呈现出重稀土富集现象.悬浮物AEC态可能由于富含铁的有机胶体、磷酸根络合和富含铁锰次生矿物相等的作用,呈现出中稀土富集.水体中溶解态稀土几乎全部是以有机络合物的形式存在;悬浮物是稀土元素的主要载体,且残渣态＞AEC态＞溶解态.     

赣南小流域水体中溶解态稀土元素地球化学特征

以亚热带富稀土背景区的赣南水系为研究对象,通过ICP-MS测定,探讨了赣南小流域水体中溶解态稀土元素的含量及分布模式,结果表明：赣南小流域溶解态稀土（DREE）含量均值为1.2845μg·L^-1,其浓度高于长江、珠江等内陆天然河流,这反映了其富稀土背景的特点。该区溶解态稀土元素分布模式表现出Ce明显的负异常和Eu正异常,这与同一背景下表土层中的Ce正异常和Eu负异常是相对应的。溶解态稀土元素的页岩标准化分布模式表现为中重稀土（MREE/HREE）富集型,这是由于该区富含重稀土矿物的易风化的氟碳钙钇矿的存在引起的。     

贵州红枫湖溶解态稀土元素地球化学研究

以中国西南碳酸岩盐地区的红枫湖及环湖河流水体为研究对象,采用液-液萃取和ICP-MS测试方法,对水中溶解态稀土元素浓度进行了测定,借以探讨碳酸盐岩水体环境下稀土元素的地球化学行为和环境效应。研究结果表明,红枫湖湖水溶解态稀土含量相对较低,∑REE总浓度分布于14.3～27.2 ng.kg-1之间,平均含量为18.24 ng.kg-1,明显低于地表水体浓度平均值。环湖河水溶解态∑REE浓度分布于4.07～102.28 ng.kg-1,平均为24.12 ng.kg-1。湖水和河水的页岩(PAAS)标准化的溶解态稀土元素配分模式都显示了显著的重稀土富集特征以及Ce元素负异常,而水化学络合计算结果显示,水体中溶解态稀土几乎以占绝对优势的碳酸盐无机络合形态存在,其他络合方式所占比例非常微小。这些都显示与相对偏碱性的水化学环境有关。     

黄山景观流域溶解态稀土元素地球化学特征

对黄山景观流域径流中溶解态稀土元素进行了研究,以探讨其地球化学特征与物质来源。结果表明,其主要来源为岩石化学风化,其次为大气输入。稀土元素含量枯水期高于丰水期,与蒸发富集效应有关。流域源头稀土元素含量高、重稀土相对富集,中下游稀土含量低、轻稀土相对富集,反映了源头花岗岩到中下游沉积岩对其相应控制。流域水体中Ce为负异常,表现出对流经原岩如花岗岩的继承;Eu为正异常,归因于花岗岩中斜长石/钾长石等矿物的优先风化释放。Y/Ho比值在空间上存在分异,主要为流经岩性不同所致,季节性分异则受到了水/粒相互作用的影响。研究表明,黄山景观流域溶解态稀土元素来源与迁移受流经岩性尤其花岗岩的影响显著。     

贵州阿哈湖溶解态稀土的垂向分布及形态特征

以中国西南季节性缺氧湖泊阿哈湖为主要研究对象,采用液-液萃取及ICP-MS测试技术,对湖泊不同深度水体中稀土元素进行分析。研究结果表明:随着阿哈湖水体深度增加,从表层至湖上层下部溶解态稀土浓度急剧升高,从湖上层底部至温跃层顶部稀土浓度快速降低,从温跃层上部至湖下层上部溶解态稀土浓度逐渐降低。湖泊颗粒物表面有机碳的矿化作用是造成溶解态稀土在湖上层浓度急剧升高的主要原因,胶体的絮凝作用使溶解态稀土在湖上层底部至温跃层顶部浓度急剧下降,在温跃层上部至湖下层上部水体中,由于新生成的MnO_2吸附作用使溶解态稀土浓度持续下降。形态模拟结果显示,溶解态稀土主要是以稀土有机结合态和稀土碳酸盐结合态两种形式存在。稀土有机络合物占总溶解态的比例遵循以下规律:湖上层温跃层湖下层;LREE-DOCMREE-DOCHREE-DOC。     

潮间带水体各要素中稀土元素的含量及其分布模式

以天津沿海潮间带为对象,通过P507萃淋树脂分离富集和ICP MS测定,探讨了潮间带海水和沉积物各要素中稀土元素的含量及分布模式。研究结果表明,潮间带海水中溶解态稀土含量均值为0.461μg·L-1,原水和沉积物孔隙水中稀土含量均值分别为4.98和0.845μg·L-1,其分布模式与内陆天然河流相似,与远洋深海差别较大。沉积物和悬浮物中稀土含量均值分别为161.2及168.1mg·kg-1,明显低于天然河流,但高于东海大陆架沉积物。潮间带沉积物、悬浮物主要源于陆地滨海土壤,其演化过程与天然河流相近,而与东海大陆架深海沉积物不同。天津沿海污染物的排海对潮间带稀土含量分布直接影响不明显。     

天津沿海潮间带沉积物中稀土元素的地球化学特征

研究了天津沿海潮间带沉积物中稀土元素(REE)的地球化学特性以及污染条件下稀土元素的环境行为特征,通过稀土分布模式特征探讨了潮间带沉积物的物质来源.结果表明(1)潮间带沉积物中14种稀土含量总和的均值为164.5mg@kg-1,但各岸段又有不同.大致以海河口为界,北部明显高于南部,均值分别为182和150mg@kg-1,均明显高于海洋沉积物稀土含量;(2)海岸带沉积物稀土形态分布特征是自北向南残渣态比例逐渐下降,铁锰氧化物态和有机结合态比例逐渐增高,与黄河、长江等大河相比,残渣态和碳酸盐态比例都显著偏低;(3)稀土元素分布模式均为轻稀土富集、铕中度亏损型,与沿海排污河及内陆大河沉积物稀土分布模式相似,而与海洋大陆架沉积物稀土分布模式有显著差别.     

深海富稀土沉积研究的若干问题

深海富稀土沉积是指稀土元素含量(包含Y)≥400×10~(-6)的一类深海沉积物,以中-重稀土富集、与钙十字沸石紧密共生而区别于其他深海沉积类型。深海富稀土沉积在太平洋和印度洋广泛分布,其稀土氧化物资源量可达1000亿t,其中重稀土资源量约为325亿t,引起了国际学术界的普遍关注。在系统总结深海富稀土沉积的调查研究历史和现状基础上,对其分布特征和规律、地球化学特征、载体矿物、富集机制、物质来源等研究进展进行了阐述,并指出了目前在稀土元素富集机制研究方面存在的几个重要问题:稀土元素的物质来源;沉积物孔隙水对于稀土元素富集的作用;钙十字沸石等共生矿物的成矿指示意义。     

热带海洋生物稀土元素生态化学特征分析研究

于中国南海南沙海域采集了30种鱼类、5种贝类和4种甲壳类热带海洋生物,以HNO3-H2 O2为消解体系,利用微波消解进行前处理,并用电感耦合等离子体质谱测定了生物体中稀土元素( Rare earth elements, REE)的含量,分析了稀土元素的生态化学特征。结果表明,微波消解-ICP-MS方法测定稀土元素,各元素的线性关系良好(r=0.9997~1.0000),检出限可达ng/L,准确度高和精密度较好,相对标准偏差(RSD, n=3)<5.0%,各稀土元素回收率在91.5%~106.7%之间。鱼类、贝类和甲壳类生物样品中稀土总量(∑REE)变化范围分别为5.02~34.8μg/kg,30.4~1481μg/kg和103~863μg/kg,3类生物对各稀土元素的富集平均含量为甲壳类>贝类>鱼类,14种稀土元素在鱼类/贝类/甲壳类内含量存在明显正相关性(r>0.80);生物体内轻稀土元素( La~Eu)含量高于重稀土元素( Gd~Lu)含量,从稀土配分模式看出,鱼类/贝类/甲壳类中REE分布模式基本一致, Gd均出现负异常,轻重稀土元素之间有明显的分馏;生物体中δEu值出现负异常,δEu值与相应海域沉积物中δEu值相近,而δCe值出现正异常;同时研究了稀土元素在生物体中的富集和沉积物沉降过程中相关性等。本研究得出的关于热带海洋鱼类/贝类/甲壳类稀土元素的含量和分配规律,可为研究南海水体环境中稀土元素的含量水平和迁移富集提供基础资料。     

Determination of Heavy Metals and Other Water Quality Parameters from the South China Sea

This study investigated the distribution and concentrations of chromium, copper, arsenic, zinc, cadmium, and lead in seawater and suspended particles in the South China Sea by collection of samples from different depths at sixteen stations. The salinity, temperature, pH, dissolved organic carbon, dissolved oxygen, and silicon concentration were also measured in seawater. The results showed that the concentration levels in seawater from 0 m to 4000 m followed this pattern: zinc > arsenic > copper > lead > chromium > cadmium. Significant correlations were observed between lead and chromium and between arsenic, cadmium, and lead at r > 0.728. Very weak correlations were observed between copper and arsenic and between copper and cadmium. The concentrations of dissolved metals and particulate metals had negative correlations except for zinc. The metal concentrations in seawater and suspended particles showed different correlation behavior with salinity, temperature, pH, dissolved oxygen, dissolved organic carbon, and silicon.     

Separation and determination of dissolved and particulate humic substances in river water

Distribution of humic and fulvic acids in participate or dissolved form is studied by using simple leaching and sorption techniques. After filtration of water sample (100–200 ml), the filter along with suspended particles is treated with 5 ml of chloroform and 3 ml of 0.1 mol/l sodium hydroxide solution. The filter dissolves completely in the organic phase, while the suspended particles remain in the aqueous phase enabling a leaching of humic substances. The leaching is repeated once more with 2 ml of 0.1 mol/l sodium hydroxide solution. The humic and fulvic acids in the combined solution are fractionated at pH l by filtration, where the membrane filter is preliminarily coated with sodium dodecyl sulfate. On the other hand, dissolved humic substances are concentrated from a 50-ml filtered sample by sorption on a DEAE-cellulose column. They are desorbed with 5 ml of 0.1 mol/l sodium hydroxide solution and fractionated at pH 1. The spectrophotometric analysis of river water reveals that fulvic acid is predominant in suspended particles as well as in filtered samples. The concentration of dissolved humic and fulvic acids is approximately ten times that of suspended particles.     

Investigation of a fiber optic surface plasmon spectroscopy in conjunction with conductivity as an in situ method for simultaneously monitoring changes in dissolved organic carbon and salinity in coastal waters

A combination surface plasmon resonance (SPR) and conductivity sensor array was developed and implemented to demonstrate the ability to differentiate among changes in dissolved organic carbon (DOC) and salinity in coastal water. The array is capable of achieving sufficient spatial and temporal data density to better understand the cycling and fate of terrestrial DOC in coastal areas. DOC is the second largest source of bioreactive carbon in the environment and plays a key role in mediating microbial activity and generation of atmospheric CO(2). In the coastal areas, the salinity is also an important property in many applications, such as leak detection for landfill liners, saltwater intrusion to drinking water, marine environment monitoring, and seasonal climate prediction. Conductivity sensors are the industry standard for determining salinity in ocean systems. However, both conductivity and refractive index sensors, such as SPR spectroscopy based sensors, respond to salinity and DOC levels. To demonstrate the capability of the SPR sensor and a conductivity sensor to collect complimentary data useful in discrimination of salinity and DOC in coastal zone water, conductivity, SPR, and temperature data were collected during passage from the Juan de Fuca ridge area returning to the University of Washington docks.     

Distribution of the rare earth elements in sediments of the Northwestern Iberian Continental Shelf

The temporal and spatial distribution of the REEs was determined, by INAA, in sediment cores collected at Northern Iberian shelf along the area between the Finisterra Cape and the mouth of Minho river, to contribute to the understanding of the origin and sedimentation processes of sediments deposited at the Continental Shelf. The distribution pattern of the REEs were flat and similar to the shales. A negative Eu anomaly was found for all the sections of the analyzed cores. Significant positive correlations between the REE and Zr and Hf contents suggest that zircon is responsible for hosting both light and heavy REEs.     

Distribution of rare earth elements in the estuarine and coastal sediments of the Daliao River System, China

The Daliao River System (DRS) estuary in Liaodong Bay features a highly industrial, urbanized, and agricultural catchment. The objective of this study was to determine the content, behavior, and distribution of the rare earth elements (REEs) in the estuarine and coastal sediments. To this end, 35 sediment samples were collected from the estuarine and coastal area and analyzed for REEs, Fe, Al, and Mn. The mean concentrations in mg kg^?1 of the sediments were 33.4 (La), 64.1 (Ce), 7.9 (Pr), 29.0 (Nd), 5.4 (Sm), 1.2 (Eu), 4.2 (Gd), 0.78 (Tb), 4.0 (Dy), 0.84 (Ho), 2.3 (Er), 0.40 (Tm), 2.3 (Yb), and 0.37 (Lu). The REE concentrations in the sediments were significantly correlated with one another (r ²  = 0.959–0.988) and the concentrations of Fe, Al, and Mn (r ²  = 0.768–0.870). The total concentration ∑REE ranged from 73.5 to 203.5 mg kg^?1, with an average of 156.0 mg kg^?1 being observed, and generally higher in the estuarine sediments than in the coastal sediments, most likely due to the salt-induced coagulation of river colloids and subsequently their accumulation at the estuarine bottom. The ratio of light REEs (∑LREE) to heavy REEs (∑HREE) was 9.4. Chondrite-normalized REE distributions were observed to be similar for the estuarine and coastal sediments, riverine suspended particles, and watershed soils of the DRS with higher LRRE enrichment than HREE and greater Eu depletion than Ce depletion. These results demonstrate that neither geochemical processes that carry soils to estuarine sediments nor long-term industrial and agricultural activities alter the distribution or fractionation of the REEs in the study area.     

Transformation and source of nutrients in the Changjiang Estuary

The concentrations of phosphate(PO43-),ammonium,nitrite,nitrate,silicate,dissolved organic nitrogen(DON),dissolved organic phosphorus(DOP),particulate phosphorus(PP)and particulate nitrogen(PN)along the salinity gradient were measured in the Changjiang Estuary in April 2007.The behavior of nutrient species along the continuum from the freshwater to the coastal zone is discussed.In the mixing zone between the riverine and marine waters,nitrate and phosphate behave non-conservatively,while silicate behaves conservatively.Nutrient import was quantified from the river load.Nutrient export to the sea was quantified from river discharge and from the salinity-nutrient gradient in the outer estuary.Using these data,a nitrogen and phosphorus budget was made.The internal estuarine fluxes played an important role in the nutrient estuarine fluxes,which accounted for approximately 41%of the nitrogen flux and 45%of the phosphorus flux.The mixing experiments in the laboratory generally reproduced well the inorganic process affecting nutrient dynamics in the Changjiang Estuary,indicating that the primary P and N transformation processes were phosphate and nitrate desorption along the salinity gradient.     

Precise measurement of the hyperfine splitting and isotope shift of8S7/2→10P9/2 transition in241Am and243Am atoms

The study of physico-chemical and biotic processes in the environment is essential to understanding the behavior of transuranic nuclides and to assess their environmental impact. Dialysis, ion exchange, and co-precipitation techniques have been used to study speciation. The dissolved fraction of^239,240Pu in coastal waters of Bombay harbor bay and in interstitial water from bottom sediments of the bay were found to be associated with organic matter. The desorption of Pu from sediments in coastal waters is influenced by salinity and carbonate. Studies indicate that, even from anoxic sediments, remobilization and the potential for migration is not significant.     

Titanium in natural surface waters: The content and coexisting forms

Results obtained in studying the content and coexisting forms of titanium in surface waters are given. It was established that the titanium concentration lies within 0.0–1180 μg/L in the world’s surface water and within 0.0–573 μg/L in the studied water bodies of Ukraine. The concentration of dissolved and suspended titanium in the water bodies studied also varies within the wide range, 0.0–86.0 and 0.0–534.6 μg/L, respectively. The concentration of its dissolved form in world’s surface water is 0.0–68.7 μg/L. The ratio of dissolved to suspended titanium in water bodies depends on the content of suspended matter and its nature. In river waters, the suspended titanium mostly dominates over the dissolved form. We found that in rivers with the high concentration of suspended matter (6.0–140.6 mg/L), mostly of mineral nature, a fraction of the suspended titanium reaches 62.3–88.6% on the average. A strong correlation between the mass of suspended matter and the concentration of suspended titanium in these surface waters shows that the nature of suspended matter affects the concentration of suspended titanium. The correlation coefficient is between 0.81–0.99 at a significance level of 0.01. The titanium content in the suspended matter and bottom sediments of world’s water bodies makes 0.2–19.8 and 0.1–24.6 mg/g of dry weight of the suspended matter, respectively. In the surface waters studied, its content ranges within 0.0–16.5 mg/g of dry weight of the suspended matter. Taking into account the average values, the titanium content in the suspended matter of the studied rivers, water reservoirs, lakes, and ponds is (mg/g in terms of dry mass): 1.0–7.5, 1.0–4.9, 1.3–3.9, and 1.2–1.3, respectively. The percentage of the adsorbed titanium in the suspended matter of the Kilia Danube delta, Kanev Reservoir, and the Lybid’ River is 91.6–97.3, 67.6–74.4, and 57.1–99.4%, respectively. The acidic (anionic), basic (cationic), and neutral fractions of the dissolved organic substances in the surface waters contained 15.7–89.4, 0.0–33.8, and 0.0–80.7% of dissolved titanium (Ti_diss) (i.e., 44.4, 13.2, and 42.4% of Ti_diss on the average). The presence of dissolved titanium in the anionic fraction shows that titanium forms complexes with humic substances or exists in the form of TiO₂ colloidal particles (nanoparticles) coated with humic substances. In the neutral fraction, a hydrated titanium oxide TiO(OH)₂ may exist as a form of its migration in natural surface waters.     

Distribution and dynamics of radionuclides and stable elements in the coastal waters off Rokkasho Village, Japan, prior to the opening of a nuclear reprocessing facility

The suspended particles floating in the seawater have the ability to biologically, as well as physically adsorb radionuclides and other elements dissolved in seawater. We have studied the distribution and composition of suspended particles, as well as the state of eluted of radionuclides in the decomposition process, in the coastal waters off Rokkasho Village, where radionuclides will be discharged from a nuclear fuel reprocessing plant in the near future.