Promoting effects in hydrogenation and hydrodesulfurization reactions on the zirconia and titania supported catalysts

Tetralin hydrogenation (HYD) and thiophene hydrodesulfurization (HDS) were studied for the supported MoS2 and WS2 sulfides, either non-promoted or promoted with Co and Ni. The supports used were ZrO2, alumina-stabilized TiO2 and pure alumina. Preparation of catalysts included presulfidation of non-promoted system with subsequent addition of promoter and resulfidation. It has been found that the nature of promoter plays determining role for the catalytic performance. The most active in both HYD and HDS reactions are Ni-promoted Mo and W catalysts, supported on ZrO2. (C) 2003 Published by Elsevier B.V.

Sorption of metals on humic acid

The sorption on humic acid (HA) of metals from an aqueous solution containing Hg(II). Fe(III), Pb, Cu, Al, Ni, Cr(III), Cd, Zn, Co and Mn, was investigated with special emphasis on effects of pH, metal concentration and HA concentration. The sorption efficiency tended to increase with rise in pH, decrease in metal concentration and increase in HA concentration of the equilibrating solution. At pH 2.4. the order of sorption was: Hg Fe Pb Cu=Al Ni Cr=Zn=Cd=Co=Mn. At pH 3.7. the order was: Hg and Fe were always most readily removed, while Co and Mn were sorbed least readily. There were indications of competition for active sites (CO2H and phenolic OH groups) on the HA between the different metals. We were unable to find correlations between the affinities of the eleven metals to sorb on HA and their atomic weights, atomic numbers, valencies, and crystal and hydrated ionic radii. The sorption of the eleven metals on the HA could be described by the equation Full-size image (1K), where Y = % metal removed by HA; X = mgHA; and A and B are empirical constants

Determination of gold, platinum and palladium in geological samples by inductively coupled plasma-mass spectrometry after separation and preconcentration with C-410 anion exchange resin

A method for the determination of Au, Pt and Pd in geological samples is described. Au, Pt and Pd can be separated and concentrated quantitatively by C-410 anion-exchange resin in the condition of 1.5 mol/L HCl with the adsorption rates of 91.2%, 100.0% and 95.7% respectively. No interference exists from coexisting elements except for Ge(IV), Cr(VI),Ti(IV) in inductively coupled plasma-mass spectrometry. The detection limits are 0.27 mug/L, 0.40 mug/L and 0.19 mug/L for Au, Pt and Pd respectively. The results of these elements in standard geological materials are in agreement with certified values with precision of 19.2% RSD for Au (n = 8), 28.1% RSD for Pt (n=8), and 15.6% RSD for Pd (n=8).

原子吸收光谱法测定人参中15个微量元素

本文研究了火焰原子吸收,石墨炉原子吸收,结合基体改进剂和平台技术,测定了人参中Pb、Ca、Co、Ni、Cr、Ba、K、Na、Cd、Mg、Fe、Cu、Zu、Mn、Sr等十五个微量元素,结果满意。

冲绳海槽晚第四纪沉积特征及其物源和环境意义

本文通过对冲绳海槽北端和南部两个海区沉积物样品的粒度、矿物和元素组成与分布特征的研究，探讨了冲绳海槽沉积物的来源，给出了一定元素组合的物源意义。通过对冲绳海槽两个柱状沉积物的粒度、矿物、元素在地层中的分布特征的研究，结合浮游有孔虫氧同位素地层划分，探讨了冲绳海槽晚第四纪沉积记录的古环境意义。 冲绳海槽陆架和陆坡沉积物明显具有陆架残留沉积的特征，沉积物主要由陆源碎屑矿物、生物碎屑、粘土矿物和少量自生矿物组成。在冲绳海槽北端，陆架和陆坡砂质区沉积物的主要来源是冰期低海面时古黄河的残留沉积，在现代沉积环境下受到海洋生物和自生沉积作用的改造；济州岛南部的细粒沉积区的物源主要是周围陆架残留沉积，在黄海暖流和黄海沿岸流的综合作用下，残留沉积中的细粒组分再沉积形成的。冲绳海槽北端海槽区沉积物主要是火山活动的产物，火山玻璃和火山型的辉石、紫苏辉石和磁铁矿明显富集。冲绳海槽南部沉积物的主要物源是长江沉积物，此外还有大量的海相生物沉积和自生沉积。对元素分布特征的研究表明，冲绳海槽陆架区富含陆源粗碎屑组分SiO_2和生源碎屑组分CaO和Sr，生物沉积对陆源沉积明显具有稀释作用。陆坡区由于受黑潮暖流的影响，往往富集Fe_2O_3和P_2O_5。在海槽区，陆源细粒组分以及与细粒组分相关的元素A1_2O_3、K_2O、Cu、Zn、Co、Ni和Cr等明显富集。利用R型因子分析的方法确定了两个研究区元素组合，结合沉积物的矿物组成给出不同元素组合的物源意义。对冲绳海槽北部(Y127孔)和南部(E017孔)两个柱状沉积物的浮游由孔虫的δ~(18)O进行了分析，将其与本区具有高分辨率的柱状样氧同位素曲线对比进行，结果表明，δ~(18)O值较敏感地记录了冲绳海槽晚第四纪以来的古环境变化。δ~(18)O的高值往往与冷期相对应，δ~(18)O的低值与暖期相对应。冲绳海槽在12ka BP左右开始了逐渐转暖的过程，在10ka BP左右(YD事件)发生了短暂的降温过程，但降温幅度很小。根据沉积物化学组成在地层中的变化规律，大部分元素较敏感地记录了全新世气候转暖事件，但是对于千年尺度的YD事件，多数元素对此没有明显的响应。冲绳海槽火山活动对沉积物的组成和沉积环境的塑造起到了至关重要的作用。根据氧同位素地层划分，在冲绳海槽北部12ka BP曾有火山活动的纪录，距今约8ka BP以来，冲绳海槽有两次较大规模火山活动的记录。火山活动往往会在短期引起气候的变冷，从而造成海区生态环境的破坏，生物沉积作用减弱。但从长期变化来看，可能是气候变暖的因素之一。火山层的主要特征为沉积物主要由粉砂组成，平均粒径明显高于周围层位，在矿物组成上表现为蒙皂石、火山玻璃和火山型的辉石、紫苏辉石和磁铁矿的含量较高，在化学组成上表现为Na_2O与Zr的同高于周围层位，而陆源性较强的元素TFe_2O_3和K_2O，以及生源组分CaCO_3和Sr的含量普遍低于周围非火山层。

传统藏药材波棱瓜的微量元素分析

对传统藏药材波棱瓜中12种微量元素进行了分析。结果显示，在波棱瓜中人体必需微量元素Cu、Fe、Zn、Mn、Co、Ni、Cr、Se等含量较高；对西藏地区不同产地的波棱瓜中的微量元素含量作比较，有极显著差异。提示在选用药材时，应重视其产地。

贵州喀斯特高原湖泊物质循环过程中的铜锌同位素地球化学－以红枫湖、阿哈湖为例

近年来铜、锌同位素地球化学研究已经进入了快速发展时期。作为新兴的同位素技术手段，铜锌同位素工具已普遍应用于地球化学、矿床学、古海洋学和生物学等多种领域，然而铜、锌同位素在湖泊生态系统中的研究却相对较少。湖泊生态系统中，重金属的迁移、循环与转化一直是地球科学家们关注的焦点，但研究手段仅局限于含量与形态的测定。因此本论文旨在通过对湖泊生态系统中铜、锌同位素的研究，揭示影响铜、锌同位素组成的主要因素，为铜、锌同位素成为湖泊系统中新的重金属示踪工具奠定基础。 本论文通过一系列条件实验，确定了用于MC-ICP-MS测定环境样品中铜、锌同位素时最佳的化学分离条件。随后选取红枫湖和阿哈湖为主要研究对象，用此实验流程对湖泊水体及其主要支流悬浮物中的铜、锌同位素的季节及剖面变化进行了初步研究。除此之外，对水体中重金属如Cu、Zn、Mn、Ni、Co、Cr、Cd和Pb的形态分布特征及物质循环进行了研究。主要得出以下几点认识： 1、环境样品中铜锌的最佳分离条件是，采用AG MP-1(100-200目)阴离子交换树脂，分别以7 mol/L HCl + 0.001% H2O2，2 mol/L HCl+ 0.001% H2O2，0.5 mol/L HNO3作为淋洗液，并分别在适当的体积接收淋洗液，可以有效地分离沉积物、植物和悬浮物等样品中的铜和锌。化学分离过程中回收率接近100％，同位素比值的变化均在误差范围以内。 2、红枫湖、阿哈湖水体及主要支流悬浮物和红枫湖生物样品中的δ65Cu分布范围为-2.64‰~1.11‰，可达到3.75‰的变化。红枫湖夏季水体悬浮物的δ65Cu变化为-0.08‰~0.25‰，入湖河流水体悬浮物δ65Cu的变化范围为0.13‰~ 1.11‰；阿哈湖夏季水体悬浮物δ65Cu的变化范围为-0.62‰~0.37‰，入湖河流水体悬浮物δ65Cu的变化范围为-1.08‰~0.60‰。两湖冬季水体悬浮物的δ65Cu值均较负。红枫湖生物样品中δ65Cu较负（-1.54‰~ 0.03‰）。 红枫湖水体悬浮物中δ65Cu的随水深的变化趋势主要受到藻类吸收作用的控制，而阿哈湖δ65Cu的随水深的变化趋势主要受到其物源的控制。说明在贫营养化湖泊中，铜同位素组成可以示踪物源；而在富营养化湖泊中，铜同位素组成则可以示踪生物活动。同时水温的垂直变化也可能是其影响因素之一。 3、红枫湖水体及其主要支流水体悬浮物中的δ66Zn变化范围分别为-0.29‰~0.26‰和-0.04‰~0.48‰，阿哈湖水体及其主要支流水体悬浮物中的δ66Zn变化范围分别为-0.18‰~0.27‰和-0.17‰~0.46‰，均表现出支流中的锌同位素组成较重的趋势。而生物样品中的δ66Zn变化范围较大，为-0.35‰~0.57‰。说明湖泊生态系统中各端元的锌同位素组成存在明显差异。 红枫湖夏季δ66Zn随着湖水深度的变化，与Chla（叶绿素）呈极显著的正相关(R=0.97)。说明锌同位素组成与藻类生物量有一定的响应关系，主要是藻类对锌的有机吸附或是吸收过程改变了锌同位素组成。阿哈湖的锌同位素组成主要受到其源区的控制作用，从而可利用锌同位素示踪源区；此外，红枫湖和阿哈湖悬浮物中的锌同位素比值均表现出夏季小于冬季，说明大气的干湿沉降可能是一个较负的锌同位素源。生物样品中的δ66Zn变化范围较大，说明由于生物作用过程导致的锌同位素分馏大于非生物过程。 4、红枫湖重金属Mn、Ni、Co、Cr、Cd和Pb的含量在南湖高于北湖，主要是羊昌湖的输入所导致；重金属入湖通量的季节性变化，直接导致了重金属含量的季节性变化。沉积物－水界面在冬夏季节，由于“富氧”和“贫氧”状态的改变，导致了溶解态Mn、Ni和Cr的季节性变化；水粒相互作用过程中，溶解有机碳（DOC）、氧化铁胶体、氧化锰胶体和水生藻类的生长繁殖，影响了重金属不同结合形态的变化。

东准噶尔卡拉麦里金矿带典型金矿床-双泉金矿的成因研究

双泉金矿床是地质工作者最近在东准噶尔地区金矿勘探中的一个新突破，地质研究和勘探程度低导致其成因还不清楚。本文通过对双泉金矿床的控矿特征、矿石矿物组成和结构构造、不同矿化阶段的矿物组合及变形特征、矿石稀土元素、氢氧同位素地球化学特征等方面的研究，探讨了双泉金矿床地质地球化学特征及成矿时代、成矿流体、成矿物质来源等，提出了该矿床的矿床成因，取得如下认识： 双泉金矿床产于下石炭统南明水组地层中，并受控于清水-苏吉泉韧性剪切带。矿石中金矿物主要以显微 (0.2mm～0.2μm)和次显微 (<0.2μm)的裂隙金、晶隙金等形式存在。矿化阶段划分为三阶段，第Ⅰ阶段黄铁矿-毒砂，第Ⅱ阶段金-石英-毒砂-黄铁矿为主要矿化阶段，第Ⅲ阶段矿化弱。利用金矿化相关的热液矿物稳定范围和毒砂的主要成分含量，通过相图得出第Ⅰ和第Ⅱ阶段温度范围分别为330～450℃和300～430℃。对矿石及近矿围岩亲硫元素组合的相关性分析和R类聚类分析得出成矿元素组合为Au-Ag-As-Sb。 卡拉麦里强应变构造带基本控制了金矿带的分布，而其中韧-脆性剪切部位控制了双泉金矿床、矿脉、矿体的产出。韧性剪切带的后两期走滑脆-韧性、脆性剪切变形控制了第Ⅰ、Ⅱ矿化阶段的金矿化。最早于中石炭世开始的区域走滑脆-韧性变形和区域最新赋矿地层主要为石炭系大致限定了双泉金矿床成矿时代为晚石炭世。 双泉金矿床成矿流体的δD为-86～-99(‰)，第Ⅰ、Ⅱ矿化阶段的δ18O值随温度降低而降低，根据水岩反应模拟计算得出初始水为变质水。两种矿石稀土元素球粒陨石配分模式呈右缓倾斜型，轻重稀土属弱分离型，δEu弱负异常，与矿区围岩(南明水组地层)基本一致。矿石轻重稀土分异程度介于围岩与蛇绿岩之间，以及热液中有大量与镁铁质、超镁铁质有关的Co、Ni、Cr、Zr、V 等组份，显示成矿流体对蛇绿岩的淋滤迁移和对围岩的叠加改造。这些反映了成矿物质来源与蛇绿岩体与围岩变质有关。 双泉金矿床形成于晚石炭世，是与韧性剪切带有关的，中高温的变质热液型金矿床。

Influence of carbonation on the acid neutralization capacity of cements and cement-solidified/stabilized electroplating sludge

Portland cement (PC) and blended cements containing pulverized fuel ash (PFA) or granulated blast-furnace slag (GGBS) were used to solidify/stabilize an electroplating sludge in this work. The acid neutralization capacity (ANC) of the hydrated pastes increased in the order of PC > PC/GGBS > PC/PFA. The GGBS or PFA replacement (80 wt%) reduced the ANC of the hydrated pastes by 30–50%. The ANC of the blended cement-solidified electroplating sludge (cement/sludge 1:2) was 20–30% higher than that of the hydrated blended cement pastes. Upon carbonation, there was little difference in the ANC of the three cement pastes, but the presence of electroplating sludge (cement/sludge 1:2) increased the ANC by 20%. Blended cements were more effective binders for immobilization of Ni, Cr and Cu, compared with PC, whereas Zn was encapsulated more effectively in the latter. Accelerated carbonation improved the immobilization of Cr, Cu and Zn, but not Ni. The geochemical code PHREEQC, with the edited database from EQ3/6 and HATCHES, was used to calculate the saturation index and solubility of likely heavy metal precipitates in cement-based solidification/stabilization systems. The release of heavy metals could be related to the disruption of cement matrices and the remarkable variation of solubility of heavy metal precipitates at different pH values.

Biomonitoring of air pollutants by using lichens (Evernia prunastri) in areas between Kenitra and Mohammedia cities in Morocco.

In this study, Evernia prunastri, a lichen growing in its natural habitat in Morocco was analysed for the concentration of five heavy metals (Fe, Pb, Zn, Cu and Cr) from eleven sites between Kenitra and Mohammedia cities. The control site was Dar Essalam, an isolated area with low traffic density and dense vegetation. In the investigated areas, the concentration of heavy metals was correlated with vehicular traffic, industrial activity and urbanization. The total metal concentration was highest in Sidi Yahya, followed by Mohammedia and Bouznika. The coefficient of variation was higher for Pb and lower for Cu, Zn and Fe. The concentrations of most heavy metals in the thalli differed significantly between sites (p<0.01). Principal component analysis (PCA) revealed a significant correlation between heavy metal accumulation and atmospheric purity index. This study demonstrated also that the factors most strongly affecting the lichen flora were traffic density, the petroleum industry and paper factories in these areas. Overall, these results suggest that the index of atmospheric purity and assessment of heavy metals in lichen thalli are good indicators of the air quality at the studied sites.

Group 6 carbene complexes derived from lithiated azoles and the crystal structure of a molybdenum thiazolinylidene complex

Fischer-type (alkoxy)azolyl carbene complexes and Ofele-Lappert-type azolylinylidene complexes were synthesised by reaction of 1-phenylpyrazol-3 -yllithium, 4-methylthiazol-2-yllithium, benzothiazol-2-yllithium, 1-methylimidazol-2-yllithium with M(CO)(5)L (L = CO, THF or Cl-; M = Cr, Mo or W) and subsequent alkylation with CF3SO3CH3. The alkylation of Fischer-type carbene complexes containing an azolyl as the organic substituent proceeded via ring opening of tetrahydrofuran. When the alkylation is carried out in THF, the carbocation CH3O(CH2)(4)(+) acts as an electrophile. Protonation rather than alkylation of coordinated imidazolyl furnished cyclic imine complexes. Changing the donor atom of a coordinated thiazole from N to C by deprotonation and alkylation afforded a carbene complex. (C) 1999 Elsevier Science S.A. All rights reserved.

Ionic liquid solvents of perhalide type for metals for extraction radioactive metals from mineral ores.

The invention relates to a process for dissolving metals (e.g., Al, Cu, Fe, Cr, Sb, Ti, and W) in perhalide contg. ionic liqs. having the formula (I), and to the extn. of metals from mineral ores; the remediation of materials contaminated with heavy, toxic, or radioactive metals; and to the removal of heavy and toxic metals from hydrocarbon streams. In the formula (I), [X] comprises at least one perhalide anion selected from [I3]-, [BrI2]-, [Br2I]-, [ClI2]-, [ClBr2]-, [BrCl2]-, or [ICl2]-, [ClI3]-. The (Cat+) is a cationic species selected from: ammonium, azaannulenium, azathiazolium, benzimidazolium, benzofuranium, benzotriazolium, borolium, cinnolinium, diazabicyclodecenium, diazabicyclononenium, diazabicyclo- undecenium, dithiazolium, furanium, guanidinium, imidazolium, indazolium, indolinium, indolium, morpholinium, oxaborolium, oxaphospholium, oxazinium, oxazolium, iso-oxazolium, oxathiazolium, pentazolium, phospholium, phosphonium, phthalazinium, piperazinium, piperidinium, pyranium, pyrazinium, pyrazolium, pyridazinium, pyridinium, pyrimidinium, pyrrolidinium, pyrrolium, quinazolinium, quinolinium, isoquinolinium, quinoxalinium, selenozolium, sulfonium, tetrazolium, iso-thiadiazolium, thiazinium, thiazolium, thiophenium, thiuronium, triazadecenium, triazinium, triazolium, iso-triazolium, and uronium. [on SciFinder(R)]

Valorização de resíduos industriais na formulação de produtos e pigmentos cerâmicos: processamento e desenvolvimento de cor

A valorização de diferentes resíduos industriais provenientes dosector de tratamento/revestimento de superfícies metálicas pode ser obtida utilizando-os como matérias-primas na formulação de pigmentos cerâmicos, sintetizados pelo método cerâmico convencional. Neste trabalho avaliou-se a viabilidade de incorporar lamas geradas pelos processos de (i) anodização, ricas em alumínio, (ii) de niquelagem e cromagem de torneiras, usadas como fonte de níquel e crómio, e (iii) da decapagem química de aços de uma trefilaria, ricas em ferro, utilizadas por si só, ou em conjunto com matérias-primas comerciais, para a obtenção depigmentos cerâmicos que coram, de forma estável, diversas matrizes cerâmicas e vítreas. Esta solução assegura ainda a inertização de potenciaisespécies perigosas presentes nos resíduos, resultando produtos inócuospara a saúde pública. Procedeu-se à caracterização de cada resíduo, em termos de composição química e mineralógica, comportamento térmico, grau de toxicidade, distribuição granulométrica, teor de humidade, etc. Verificou-se a constância das características das lamas, recorrendo à análise de lotes recolhidos em momentos distintos. Os resíduos são essencialmente constituídos por hidróxidos metálicos e foram utilizados após secagem e desagregação. No entanto, a lama de anodização de alumínio sofreu um tratamento térmico suplementar a 1400ºC. O método de síntese dos pigmentos englobou as seguintes etapas: (i) doseamento; (ii) homogeneização; (iii) calcinação; (iv) lavagem e moagem.Procedeu-se à caracterização dos pigmentos, avaliando a cor por espectroscopia de reflectância difusae pelo método CIELAB e determinando as características físico-químicas relevantes. Posteriormente, testou-se o seu desempenho em produtos cerâmicos distintos (corpos e vidrados), aferindo o desempenho cromático e a estabilidade. Numa primeira fase, desenvolveram-se e caracterizaram-se tipos distintos de pigmentos: (i) com base na estrutura do corundo (ii) verde Victória deuvarovite (iii) violeta de cassiterite com crómio (iv) pigmento carmim de malaiaíte; (v)pretos e castanhos com base na estrutura da espinela. Aprofundaram-se depois os estudos do pigmento carmim de malaiaítee do pigmento preto com base na estrutura da espinela. O pigmento carmim de malaiaíte, CaSnSiO5:Cr2O3, é formulado coma lama gerada no processo de niquelagem e cromagem. Avaliou-se a influência do teor de lama na temperatura de síntese e na qualidade cromática, em comparação com um pigmento formulado com reagentes puros. O pigmento preto com estrutura de espinela de níquel, crómio e ferro, foii formulado exclusivamente a partir das lamas geradas nos processos de cromagem/niquelagem e de decapagem química do aço. Avaliaram-se as características cromáticas e o grau de inertização dos elementos tóxicospresentes, em função da estequiometria e do tratamento térmico. Estudou-se ainda um novo sistema com base na estrutura da hibonite(CaAl12O19), que permite a obtenção de pigmentos azuis e que utiliza a lama de cromagem e niquelagem. As espécies cromóforas (Ni2+ ou Co2+) assumem coordenação tetraédrica quando substituem os iões Al3+ que ocupam as posições M5 da rede da hibonite. A formação simultânea de anortite permite reduzir a temperatura de síntese.Para além do carácter inovador deste pigmento de dissolução sólida, a qualidade cromática e a sua estabilidade são interessantes. Além disso, os teores de cobalto ou níquel são reduzidosrelativamente aos utilizados em formulações comerciais de pigmentos azuis, o que se traduz em importantes vantagens económicas e ambientais.

Trace metals in size-fractionated particulate matter in a Portuguese hospital: exposure risks assessment and comparisons with other countries

Hospitals are considered as a special and important type of indoor public place where air quality has significant impacts on potential health outcomes. Information on indoor air quality of these environments, concerning exposures to particulate matter (PM) and related toxicity, is limited though. This work aims to evaluate risks associated with inhalation exposure to ten toxic metals and chlorine (As, Ni, Cr, Cd, Pb, Mn, Se, Ba, Al, Si, and Cl) in coarse (PM2.5–10) and fine (PM2.5) particles in a Portuguese hospital in comparison with studies representative of other countries. Samples were collected during 1 month in one urban hospital; elemental PM characterization was determined by proton-induced X-ray emission. Noncarcinogenic and carcinogenic risks were assessed according to the methodology provided by the United States Environmental Protection Agency (USEPA; Region III Risk-Based Concentration Table) for three different age categories of hospital personnel (adults, >20, and <65 years) and patients (considering nine different age groups, i.e., children of 1–3 years to seniors of >65 years). The estimated noncarcinogenic risks due to occupational inhalation exposure to PM2.5-bound metals ranged from 5.88×10−6 for Se (adults, 55–64 years) to 9.35×10−1 for As (adults, 20–24 years) with total noncarcinogenic risks (sum of all metals) above the safe level for all three age categories. As and Cl (the latter due to its high abundances) were the most important contributors (approximately 90 %) to noncarcinogenic risks. For PM2.5–10, noncarcinogenic risks of all metals were acceptable to all age groups. Concerning carcinogenic risks, for Ni and Pb, they were negligible (<1×10−6) in both PM fractions for all age groups of hospital personnel; potential risks were observed for As and Cr with values in PM2.5 exceeding (up to 62 and 5 times, respectively) USEPA guideline across all age groups; for PM2.5–10, increased excess risks of As and Cr were observed particularly for long-term exposures (adults, 55–64 years). Total carcinogenic risks highly (up to 67 times) exceeded the recommended level for all age groups, thus clearly showing that occupational exposure to metals in fine particles pose significant risks. If the extensive working hours of hospital medical staff were considered, the respective noncarcinogenic and carcinogenic risks were increased, the latter for PM2.5 exceeding the USEPA cumulative guideline of 10−4. For adult patients, the estimated noncarcinogenic and carcinogenic risks were approximately three times higher than for personnel, with particular concerns observed for children and adolescents.

Studies on the Nature and Chemistry of Sediments and Water of Periyar and Chalakudy Rivers, Kerala, India

The present study is an attempt to address issues related to sediment properties like texture, mineralogy and geochemistry as well as water quality of two important rivers of central Kerala-the Periyar and the Chalakudy rivers. The main objectives of the study are to investigate the textural and mineralogical characteristics as well as transportation and depositional mechanisms of the sediments of Periyar and Chalakudy rivers, to find out the geochemical variability of organic carbon, phosphorus and certain major (Na,K,Ca and Mg) and minor/trace(Mn,Pb,Ni,Cr, and Zn) elements in the bulk sediments and mud fraction of these rivers, to evaluate the status of heavy metal pollution registered in the sediments of these rivers, to assess the physico-chemical characteristics and water quality of Periyar and Chalakudy rivers and to estimate the dissolved nutrient flux through the Periyar and Chalakudy rivers into the receiving coastal waters. The granulometric characteristics as well as statistical parameters of the sediments of Periyar and Chalakudy rivers depend on the flow pattern controlled by the gradient of the terrain. Compared to Periyar, fluctuations in the dispersal of particles are more in Chalakudy river. In Periyar river, the P and Fe in bulk sediments show a positive correlation with C-org, while in Chalakudy river, both the elements are related to THM concentration. In general, C-org, Fe and P Shows an increasing trend downstream. In Periyar river, the P and Fe in bulk sediments show a positive correlation with C-org, while in Chalakudy river, both the elements are related to THM concentration. Among these two rivers, the pollution of water is several fold higher in Periyar river due to influx due to influx of considerable quantity of liquid and solid wastes of industrial/domestic/urban origin. Nutrient analysis reveals 2-3 times increase in N and P during monsoon season whereas SiO2-Si shows a decreasing trend.