Geochemical and mineralogical characteristics of elephant geophagic soils in Udawalawe National Park,Sri Lanka

Geophagy or deliberate ingestion of soils was observed among Asian elephants (Elephas maximus) in the Udawalwe National Park, Sri Lanka, for several years. The geochemical and mineralogical composition of the clayey soil layers which are purposefully selected and eaten by elephants in the park were studied, in order to identify the possible reasons for elephant geophagy. The concentrations of major and trace elements were determined by means of X-ray fluorescence spectrometry in 21 soil samples from eight geophagic sites and six soil samples collected from four non-geophagic sites. The mineralogical composition of selected soil samples was investigated using X-ray diffractometry (XRD). These geochemical analyses revealed that geophagic soils in the study areas are deeply weathered and that most of the elements are leached from the soil layers under extreme weathering conditions. The XRD data showed that the soils of the area consisted mainly quartz, feldspar, and the clay minerals kaolinite, Fe-rich illite, and smectite. Although no significant geochemical differences were identified between geophagic and non-geophagic soils, a clear difference was observed in their clay mineralogical content. Soils eaten by elephants are richer in kaolinite and illite than non-geophagic soils, which contain a higher amount of smectite. It is suggested that elephants in Udawalawe National Park ingest soils mainly not to supplement the mineral contents of their forage but to detoxify unpalatable compounds in their diet.     

Accumulation of some metals in Morinda lucida from Nigeria

Transfer coefficients of the four metals As, Cd, Hg, and Pb were determined in the leaves and barks of Morinda lucida collected in Nigeria, with the view to quantify relative differences in the bioavailability of the metals to these parts of the plant. Samples were acid digested and the levels of the metals in the digestates were determined using an atomic absorption spectrophotometer. Certain properties of the soils, i.e., pH, clay fraction, electrical conductivity, cation exchange capacity, and organic matter, were also determined. The latter influence the bioavailability of the metals. All parameters correlated with the concentrations of the metals in soils. Transfer coefficient values recorded for Cd and Pb in various tissues of M. lucida Benth were within the expected ranges, while those of As and Hg showed elevated topsoil concentrations of metals. The order of bioavailability of the metals and their bioaccumulation in the tissues of M. lucida Benth was Hg > Cd > As > Pb. Stem barks of the plant showed the least bioaccumulation of all four metals and hence are most suitable for therapeutic purposes. Vegetative parts of M. lucida Benth used for therapeutic purposes should be sourced at sites that will give low transfer coefficient in order to reduce human exposure to toxicity associated with ingestion of heavy metals.     

Highlights of some environmental problems of geomedical significance in Nigeria

This paper attempts to discuss the links between the geochemical composition of rocks and minerals and the geographical distribution of diseases in human beings in Nigeria. We know that the natural composition of elements in our environment (in the bedrock, soils, water, and vegetation) may be the major cause of enrichment or depletion in these elements and may become a direct risk to human health. Similarly, anthropogenic activities such as mining and mineral processes, industrial waste disposal, agriculture, etc., could distort the natural geochemical equilibrium of the environment. Thus, the enrichment or depletion of geochemical elements in the environment are controlled either by natural and/or anthropogenic processes. The increased ingestion of toxic trace elements such as As, Cd, Hg, Pb, and F, whether directly or indirectly, adversely affects human health. Of these, Cd has most dangerous long-term effect on human health. Environmental exposure to As and Hg is a causal factor in human carcinogenesis and numerous cancer health disorders. Available information on iodine deficiency disorder (IDD) in Nigeria indicates goiter prevalence rates of between 15% and 59% in several affected areas. There have been reported cases of dental fluorosis resulting from intake of water with fluoride content >1.5 ppm. Dental caries among children shows an overall prevalence rate of 39.9%. Within the Younger Granite province in central Nigeria, cases of cancer and miscarriages in pregnant women have been linked to natural radiation These examples and a number of others from the existing literature underscore the pressing need for the development of collaborative research to increase our understanding of the relationship between the geographical distribution of human and animal diseases in Nigeria and environmental factors. We submit that such knowledge is essential for the control and management of these diseases.     

Chemical fractionation of metals in core sediments of Orogodo River,southern Nigeria

Sequential chemical extraction of metals (Cu, Ni, Mn, Fe, Pb, Cr, and Zn) from core sediments of the Orogodo River was carried out with a view of providing information on the phase distribution of these metals with respect to depths and seasons. The results indicate that copper was speciated into organic matter/sulfide, Fe–Mn oxides, and residual forms at 0–5?cm depth while at deeper sections copper was predominantly in the residual form. Nickel was speciated mainly into Fe–Mn oxides and residual forms. The average of lead in various particulate phases of the sediment are 0–100% for residual; 0–8% for carbonate; 0–16.2% for exchangeable; 0–10% for organic matter/sulfide form and 22–56% for Fe–Mn oxides bound metals. Manganese was speciated into exchangeable (10–36%) and Fe–Mn oxides bound (10–48%) at the surface layers of 0–20?cm depths and predominantly in the residual form in deeper sections implying partitioning into trioctahydral clay and/or well-defined crystalline oxides. Iron was predominantly in the Fe–Mn oxides and residual fractions, less than 8% in the organic fraction, and 24.4–37.3% in the exchangeable and carbonates fractions at the surface. The percentage contributions of iron in the exchangeable and carbonate fractions decreased to 3.2% at 55–60?cm depth. The amount of chromium in the exchangeable fraction ranged from 0% to 7% for exchangeable; 0–26.5% for organic matter/sulfide bound; 3.8–17.9% for Fe–Mn oxides; and 46.8–100% for residual fraction. The mobility factors of the metals indicated that these metals were relatively mobile at top sections as compared with deeper sections. The overall picture of metal mobility and availability indicates potential contamination risk by Fe, Zn, Mn, and Pb in the Orogodo River sediment system.     

Trace metal contents in some brands of canned beef in Nigeria

The concentrations of cadmium, chromium, copper, lead, zinc, manganese, iron, cobalt, and nickel in some brands of canned beef in Nigerian markets were determined by atomic absorption spectrophotometry. The mean concentration ranges for these metals in mg?kg^?1 were 0.02–0.37 for Cd, <0.04–0.75 for Cr, 1.1–2.4 for Cu, <0.001–1.5 for Pb, 1.1–8.0 for Zn, <0.04–0.57 for Mn, 13.8–28.8 for Fe, 0.05–0.26 for Co, and 0.8–5.9 for Ni. The estimated dietary intake of metals from these products did not indicate any risk since the values were far below the permissible dietary intakes.     

Disturbance of the Macroinvertebrate communities of bank-root biotope of a river in southern Nigeria

The impact of disturbance on the macroinvertebrate community was investigated in the biotope of a river catchment area. A total of 56 and 18 taxa were recorded at Stations 1 and 2, accounting for 71 and 29% individual organisms, respectively. Twelve taxa were common at both stations. Baetidae (Ephemeroptera) constituted the predominant group with the 46% density at the upstream biotope of Station 1, whereas, family Hydrobidae (Mollusca) dominated numerically the downstream Station 2. Data revealed that months of sampling at stations significantly influenced the occurrence and abundance of the major groups. Three distinct patterns of seasonal affiliation among the benthos were observed. Monthly variation in species diversity occurred. The macroinvertebrate community was affected by disturbances at the downstream bank-root biotope, limiting the occurrence of life forms to a few adaptable groups.     

The geochemistry of geophagic material consumed in Onangama Village,Northern Namibia: a potential health hazard for pregnant women in the area

Environmental Geochemistry and Health - Ingestion of geophagic materials might affect human health and induce diseases by different ways. The purpose of this study is to determine the geochemical...     

攀枝花市水系沉积物与土壤中重金属的地球化学特征比较

水系沉积物和土壤都是表生作用的产物,是环境中污染物质的重要受纳体,但两者在物质来源和受纳污染物方面又有不同。重金属通过不同方式进入到水系沉积物和土壤之中产生污染,对于区域环境具有重要的影响。为了了解攀枝花市水系沉积物和土壤中重金属元素地球化学特征的异同和污染状况,在攀枝花市范围内系统采集了水系沉积物和土壤样品,从环境地球化学角度,应用地球化学方法研究了攀枝花市水系沉积物及土壤中重金属的地球化学特征,应用地质累积指数法评价了污染情况,并对二者进行了比较研究。结果表明,攀枝花市水系沉积物中重金属的含量普遍高于土壤;水系沉积物和土壤中重金属的分布具有相似的特征;水系沉积物中重金属的污染程度高于土壤,但总体上来说,重金属的污染程度较小。两者的污染程度不同是因为接受污染物的方式不同;两者的分布趋势相同,说明具有相同或相近的污染来源。     

Positive anomalous concentrations of Pb in some gabbroic rocks of Afikpo basin southeastern Nigeria

Gabbroic rocks have intruded the sedimentary sequence at Ameta in Afikpo basin southeastern Nigeria. Petrographic and geochemical features of the rocks were studied in order to evaluate their genetic and geotectonic history. The petrographic results show that the rocks contain plagioclase, olivine, pyroxene, biotite, iron oxide, and traces of quartz in three samples. Major element characteristics show that the rocks are subalkaline. In addition, the rocks have geochemical characteristics similar to basaltic andesites. The trace elements results show inconsistent concentrations of high field strength elements (Zr, Nb, Th, Ta), moderate enrichment of large-ion lithophile elements (Rb, Sr, Ba) and low concentrations of Ni and Cr. Rare earth element results show that the rocks are characterized by enrichment of light rare earth elements, middle rare earth elements enrichment, and depletion of heavy rare earth elements with slight positive europium anomalies. Zinc concentrations are within the normal range in basaltic rocks. There are extremely high concentrations of Pb in three of the rock samples. The high Pb concentrations in some of these rocks could be as a result of last episodes of magmatic crystallization. The rocks intruded the Asu River Group; organic components in the sedimentary sequence probably contain Pb which has been assimilated into the magma at the evolutionary stage of the magma. Weathering of some rocks that contain galena could lead to an increase in the concentration of lead in the gabbroic rocks, especially when the migration and crystallization of magma take place in an aqueous environment. Nevertheless, high concentration of lead is hazardous to health and environment.     

Assessment of heavy metal contamination of Great Kwa River estuary,southeastern coast of Nigeria by index of geochemical accumulation

Heavy metal concentration of the Great Kwa River estuary at the southeastern coast of Nigeria was assessed using an index of geochemical analysis (Igeo). Sampling from surface sediment was conducted quarterly for a period of one year, reflecting seasoning changes in the area. Igeo was calculated from the differences between actual current measurements and subtracted from background levels of “average shale” measurement. Based upon metals analyzed (Fe, Mn, Zn, Ni, Cu, Pb, Hg, and Cd), it was observed that there was a strong indication of potential ecological risk attributed to Cd, Zn, and Ni in the surface sediment. For effective control of pollution by metals in this fragile ecosystem, several recommendations were made including control of anthropogenic activities especially those of petroleum industry from offshore oil wells located in the area.     

Effect of some herbicides used in Nigeria on Rhizobium phaseoli, Azotobacter vinelandii and Bacillus subtilis

The effect of three herbicides namely Agroxone, Atranex 50SC and 2,4-Damine on Azotobacter vinelandii, Rhizobium phaseoli and Bacillus subtilis were studied. These bacteria were isolated from a bean-garden in Lagos. The results revealed that 2, 4-Damine was the most toxic of the three herbicides studied and Azotobacter vinelandii was found to be most sensitive to the herbicides. There was a reduction in LC50 of herbicides with increased number of days. The percentage survival decreased with increased concentration of herbicides and days for Rhizobium phaseoli and Azotobacter vinelandii while an initial reduction in population was followed by increased percentage survival of organisms for Bacillus subtilis.     

Relevance to primary health care of village health workers and traditional birth attendants in rural areas of Oyo State,Nigeria

The objectives of the study were to investigate the relevance of traditional birth attendants (TBAs) and village health workers (VHWs) in primary health care of rural people, to identify problems encountered by TBAs/VHWs in the course of their activities, and to determine the attitude of residents (clients and non-clients) towards the services provided. The study area was rural Ibarapa in Oyo State, Nigeria. The sample consisted of 30 VHWs, 30 TBAs, their clients (120) and 240 local residents. Data were collected through a validated and pre-tested structured interview guide. The study concluded that VHWs and TBAs play a tremendous role and provide essential services in primary health care delivery for rural people. Problems encountered by VHWs and TBAs were irregular supply of drugs, unsatisfactory monitoring, supervision and evaluation by higher health officers from the local government and primary health care centres and poor remuneration. The residents were positive and satisfied with the services provided by the VHWs and TBAs and need their services.

It is recommended that: the local government authorities should carefully examine the modus operandi of the VHWs and TBAs with a view to revamping, reorganizing, rejuvenating and refocusing to make the best use of them; regular (quarterly) training should be organized by the local council for the VHWs and TBAs on current issues, ailments, symptoms and treatments; drugs and other essential supplies should be made available to the VHWs and TBAs and incentives and remuneration accruable to them should be reviewed upwards.     

Evaluation of rare earth elements in groundwater of Lagos and Ogun States,Southwest Nigeria

Rare earth elements in our environment are becoming important because of their utilization in permanent magnets, lamp phosphors, superconductors, rechargeable batteries, catalyst, ceramics and other applications. This study was conducted to evaluate the level of rare earth elements (REE) and the variability of their anomalous behavior in groundwater samples collected from Lagos and Ogun States, Southwest, Nigeria. REE concentrations were determined in 170 groundwater samples using inductively coupled plasma-mass spectrometry, while the physicochemical parameters were determined using standard methods. Lagos State groundwater is enriched with REE [sum REEs range (mean ± SD)]; [0.365–488 (69.5 ± 117)] µg L^?1 than Ogun State groundwater [sum REEs range (mean ± SD)]; [1.14–232 (22.6 ± 41.1)] µg L^?1. Boreholes are more enriched with REEs than wells. Significant (P < 0.05) positive correlation (R = Pearson) was recorded in Lagos State groundwater between sum REEs and Fe (R = 0.55). However, there were no significant correlations between sum REEs, pH (R = 0.073) and HCO₃ ^2? (R = 0.157) in Ogun State groundwater. Chondrite-normalized plot shows that Lagos groundwater exhibits positive Ce anomaly, while Ogun State groundwater does not. The source of REE in Lagos State may be from the ocean and leaching from wastes dumpsites, while the source in Ogun State groundwater may be from the rocks.     

Influence of industry on the geochemical urban environment of Mieres (Spain) and associated health risk

This study is concerned with the elemental composition of soils and street dust collected in an historical industrial city of approximately 27 000 inhabitants, where old Hg mining and metallurgical activities strongly affected the load of heavy metals in the urban environment. For the purpose of the study, representative samples of soils and street dust were collected at different locations in the whole urban area (3 km²). Elevated mean concentrations of As in soils and street dust (69 and 135 g g^–1, respectively), and Hg (3.07 and 4.24 g g^–1, respectively), compared to background levels and to those found in other cities, reflect the anomalous geochemical nature of these materials and the strong influence exerted by the old mining sites.     

莱州湾南岸滨海湿地维管束植物的区系特征及保护

在2003～2005年多次实地调查并参照相关资料基础上,对莱州湾南岸滨海湿地进行了植被类型划分和湿地维管束植物生态类群划分,利用统计方法分析了研究区湿地维管束植物区系较大科、属的构成,蕨类植物种的地理分布区类型、种子植物属的地理分布区类型,维管束植物区系保护面临的问题及对策.研究表明,莱州湾南岸滨海湿地植被分4个植被型、25个植物群落,由48科129属197种维管束植物构成,这些维管束植物分盐生植物,水生植物,湿生植物和中生、旱生植物4大生态类群.维管束植物区系的主体为菊科、禾本科、莎草科等含5种及5种以上的13个较大科,从维管束植物属的分布区类型构成来看,种子植物中世界分布属最多,达40属,占种子植物总属数的32%,这反映了湿地植被的隐域性特征;温带和热带分布区成分作为区系成分的主体共80属,占种子植物总属数的64%.盐田、养殖池、道路建设,海岸侵蚀,地下咸、卤水入侵,气候干旱,河流断流等自然、人为原因导致莱州湾南岸滨海湿地退化,植被发生退化演替,区系中一些珍稀濒危植物受到日益严重的威胁.提出了对退化湿地进行生态恢复与重建,推广生态旅游、生态养殖等可持续的滨海湿地利用方式,建设湿地自然保护区和生态环境监测网络等莱州湾南岸滨海湿地维管束植物区系保护对策.     

氟与健康的环境流行病学研究

氟是与机体健康密切相关的微量生命元素,原生环境中氟过量或缺乏均会导致机体产生疾病。氟对人类健康的影响已成为全球性的环境健康问题。综合国内外近年来的相关资料,作者概述了环境生态系物质中氟的含量、分布及化学行为,阐述了氟对机体的健康效应,分析了我国地氟病的现状,并指出了今后在氟与健康研究领域中应关注的问题。     

Photodegradation of fenamiphos on the surface of clays and soils

The photodegradation of the organophosphorus fenamiphos was studied in various clay matrices: montmorillonite, kaolin and the mineral components of two soils collected from two different sites: Settat (S) and Berrechid (B). The degradation was shown to be mainly due to the direct excitation of fenamiphos and was similar for all the matrices with a two-step kinetics : a fast and a slower one. The first step rate obtained at the surface of montmorillonite was slightly lower than that determined at the surface of kaolin. The fenamiphos degradation process clearly depended on the amount of humic substances and iron(III). The latter component accelerated the disappearance of fenamiphos, while humic substances clearly inhibited the process. The degradation rate increased in the presence of water and was mainly due to the involvement of the photohydrolysis process leading to the scission of the P–O bond. The formation of the main by-products, sulfoxide, sulfone and phenol derivatives, were elucidated by HPLC/MS.