Trends in sediment metal concentrations in the River Avoca, South-East Ireland

Variation in sediment metal concentrations in the River Avoca, which is severely polluted by acid mine drainage (AMD) discharged from the abandoned sulphur and copper mines in Avoca, is reported. A survey of surface and subsurface sediments was repeated after seven years during exceptionally low flow conditions in 2001. The present study found that the reference (up-stream) site used in the original 1994 study was itself impacted by AMD, showing sediment metal enrichment by AMD to be greater than originally thought. The new reference site contained elevated Pb (570 µg g^–1) in the subsurface sediment due to abandoned Pb-Zn mines 25 km further upstream. Concentrations of Cu (43 µg g^–1), Zn (349 µg g^–1) and Fe (4.0%) were normal for uncontaminated rivers. All the downstream sites showed sediment metal enrichment arising from the AMD (Cu and Zn p < 0.001; Fe p < 0.01). Subsurface concentrations of metals immediately below the mixing zone were Cu 904 µg g–1 (sd 335), Zn 723 µg g–1 (sd 93), Fe 6.3% (sd 1.5) and Pb 463 µg g^–1 (sd 279). Monthly variation in metal concentrations at sites was not significantly different (p > 0.05). Although surface sediment metal concentrations were more variable, they followed similar trends to subsurface sediment. There were no significant differences in the subsurface sediment concentrations for either Cu or Zn over the period 1994 and 2001 immediately below the mines, although at the lowest site Zn had decreased by 35% over the period (p < 0.01). However there was a significant (p < 0.01) decrease over the period in the Fe concentration at all the impacted sites. This corresponds to a reduction in Fe concentration in the AMD and indicates that some remediation has occurred in the river since 1994.     

Metal contamination of active stream sediments in upper Weardale,northern Pennine Orefield,UK

In the Upper Weardale area the headwaters of the River Wear bisect the Northern Pennine Orefield, where Pb-Zn-F-Ba vein-type mineralisation has been exploited since the Roman Conquest. The area contains evidence of open pit, underground and hydraulic mining of base metal ores, associated mineral processing and smelting, exploitation of ironstones during the industrial revolution, recent extraction of fluorite and active quarrying. The aim of this study was to determine the extent of modern sediment contamination arising from these past activities. Samples of active stream sediments were collected from all major drainage channels at 1 km intervals. The sediments were analysed for Pb, Zn, Ba, Mn, Fe, Co, Ni, Cu, Cr, As, Sb, Ag and compared to data from earlier regional geochemical surveys of low order drainage samples using ArcView software. The significance of contamination levels was assessed using the Ontario aquatic sediment quality guidelines. Our results indicate widespread contamination of some major drainages by Pb, Mn, Zn and As at concentration levels anticipated to significantly affect use of the sediments by benthic organisms. Furthermore, Pb contamination shows persistence in stream sediments downstream towards agricultural areas of the floodplain and drinking water abstraction points, above which interaction with colliery mine water discharges may occur.     

Geochemistry of leachates from the El Fraile sulfide tailings piles in Taxco, Guerrero, southern Mexico

Leachates from the El Fraile tailings impoundment (Taxco, Mexico) were monitored every 2 months from October 2001 to August 2002 to assess the geochemical characteristics. These leachates are of interest because they are sometimes used as alternative sources of domestic water. Alternatively, they drain into the Cacalotenango creek and may represent a major source of metal contamination of surface water and sediments. Most El Fraile leachates show characteristics of Ca–SO₄, (Ca+Mg)–SO₄, Mg–SO₄ and Ca–(SO₄+HCO₃) water types and are near-neutral (pH=6.3–7.7). Some acid leachates are generated by the interaction of meteoric water with tailings during rainfall events (pH=2.4–2.5). These contain variable levels of SO₄ ²⁻ (280–29,500 mg l⁻¹) and As (<0.01–12.0 mg l⁻¹) as well as Fe (0.025–2352 mg l⁻¹), Mn (0.1–732 mg l⁻¹), Zn (<0.025–1465 mg l⁻¹) and Pb (<0.01–0.351 mg l⁻¹). Most samples show the highest metal enrichment during the dry seasons. Leachates used as domestic water typically exceed the Mexican Drinking Water Guidelines for sulfate, hardness, Fe, Mn, Pb and As, while acidic leachates exceed the Mexican Guidelines for Industrial Discharge Waters for pH, Cu, Cd and As. Speciation shows that in near-neutral solutions, metals exist mainly as free ions, sulfates and bicarbonates, while in acidic leachates they are present as sulfates and free ions. Arsenic appears as As^(V) in all samples. Thermodynamic and mineralogical evidence indicates that precipitation of Fe oxides and oxyhydroxides, clay minerals and jarosite as well as sorption by these minerals are the main processes controlling leachate chemistry. These processes occur mainly after neutralization by interaction with bedrock and equilibration with atmospheric oxygen.     

A spatial-temporal optimization approach to watershed management: Acid mine drainage treatment in the Cheat River watershed, WV, USA

Most water management studies concentrate on the inter-temporal allocation problem or, more recently, spatial dynamics - but not both. While early spatial-temporal studies focused on the allocation of water quantity, this paper presents an approach to water quality analysis that incorporates both spatial and temporal dynamics in a watershed framework. The acid mine drainage (AMD) problem in the Cheat River watershed of West Virginia, USA, serves as a case study and provides an opportunity to test the modeling approach developed. The empirical models are written in General Algebraic Modeling System (GAMS) and solved using the CPLEX mixed integer programming package. The results suggest that available investments should be concentrated in heavily impaired stream segments. The model can be used to assess the economic implications of alternative watershed Total Maximum Daily Load (TMDL) implementation or other management strategies.     

磷胁迫对水稻基因型根系形态及吸收铁锰铜锌的影响

采用营养液培养方法研究了缺磷胁迫下4种水稻基因型(90-90—1、金23A、90-68-1、CDR22)的根系形态变化情况及其吸收微量元素铁、锰、铜、锌的影响。结果表明，(1)磷胁迫下，每个基因型在磷胁迫下其根系形态发生了明显变化、如根长、根冠比均呈增加趋势，并且根表有红棕色铁氧化物膜包被。(2)磷胁迫下根系形态的变化影响了水稻对生长介质中铁、锰、铜、锌的吸收：正常水稻植株中铁、锰、锌的含量高于磷胁迫植株，其中磷营养状况对水稻吸收铁、锰影响最明显；而磷营养状况对水稻植株铜含量的影响与铁、锰、锌正好相反，且影响程度较小。     

Mercury in surface sediments and benthic organisms from Guaymas Bay,east coast of the Gulf of California

In order to know the concentration of mercury in surface sediments, macroalgae and clams from Guaymas Bay, Mexico, 20 surface sediment samples and several individuals of Codium amplivesciculatum (3), Enteromorpha clathrata (4), Gracilaria subsecundata (2), Ulva lactuca (2), Chione subrugosa (80) and Crassostrea gigas (40) were collected and their Hg concentration was measured by a cold vapor Hg analyzer, after acid digestion. In addition, granulometric analysis and quantification of total organic carbon, aluminum, iron and manganese contents in sediments were performed. A Pearsons correlation matrix was determined and, the enrichment factor, the geoaccumulation index and the biota-sediment accumulation factor were calculated. Mercury concentrations in sediments ranged from 0.3 to 2.3 μg g⁻¹, with the central and northern portions showing the highest values. Macroalgae had a content of Hg that oscillated from 0.058 to 0.134 μg g⁻¹, while the average concentrations of this metal for clams and oysters were 0.063 and 0.230 μg g⁻¹, respectively. A clear effect of Guaymas City and the anthropogenic activities carried out around the Guaymas Bay has been observed and the enrichment factor and the geochemical index suggest that sediments from this coastal ecosystem are moderately to strongly contaminated with Hg. However, according to the figure of the maximum human consumption of Hg per week recommended by the World Health Organization, people can ingest clams without risk to their health.     

Fuzzy comprehensive assessment of metal contamination of water and sediments in Ondo Estuary,Nigeria

A more reliable methodology for evaluating metal contamination of coastal water and sediments using fuzzy comprehensive assessment (FCA) is presented by this study. Ten metals (As, Cd, Cu, Cr, Fe, Mn, Ni, Pb, V and Zn) were investigated in water and sediments from ten sampling sites and formulated into fuzzy matrix based on three contamination classifications of pristine, moderately enriched and extremely impacted categories using regulatory limits as criteria. The products of the matrices from membership function of the observed data and the weight matrices generate indices that classify the degree of metal impact on the sites. The results of the FCA show that the estuary is negatively impacted by metals in a range of 45.5–75.1% membership in the extremely impacted category with potential adverse effects on the ecosystem of the neighbouring Atlantic Ocean. The crude oil exploration activity at site 1 is the major source input of the metals beside Fe and Mn which are natural to the geological structure of the area while domestic waste discharges contribute notably to metal contamination in some sites.     

东湖、汤逊湖和梁子湖沉积物磷形态及pH对磷释放的影响

文章采用淡水沉积物中磷形态标准测试程序(SMT)研究了东湖、汤逊湖和梁子湖沉积物中磷的形态分布,并比较了不同pH条件下沉积物磷释放特征的差异性。结果表明:东湖沉积物总磷质量分数最高,平均值1.232 mg.g-1,其次为汤逊湖(0.762mg.g-1),梁子湖沉积物总磷质量分数最低(0.572 mg.g-1);3个湖泊上覆水总磷质量浓度也表现出类似的变化规律,线性相关性分析显示上覆水中总磷质量浓度与沉积物总磷质量分数显著正相关。东湖和梁子湖沉积物总磷中无机磷和有机磷所占比例较接近,汤逊湖无机磷所占比例远低于有机磷。不同湖泊之间磷形态的分布并没有一定的规律性,湖泊的地理分布以及人为因素可能是造成磷形态差异的主要因素。当pH为2.0~7.0时,3个湖泊沉积物中溶解性活性磷(SRP)释放量均呈先增加后减小的趋势;当pH为7.0~12.0时,SRP释放量呈增加趋势。相关分析结果表明,SRP的释放与有机质的质量分数无显著相关性。方差分析结果显示3个湖泊沉积物在黏粒和粉粒组成上均没有显著差异(P>0.1),表明实验样品的粒径组成不是造成各个湖泊间磷释放差异的原因。不同pH条件下,SRP释放量与沉积物总磷质量分数显著正相关;酸性环境下,SRP释放量与酸式磷(HCl-P)的相关性优于碱式磷(NaOH-P),碱性环境下则刚好相反。     

长江口南支沉积物对卤虫的毒性效应研究

以Ⅱ-Ⅲ龄卤虫幼体（Artemia salina）为受试生物,开展生物检测试验,研究长江口南支沉积物的毒性效应。生物检测结果表明长江口南支部分站位的沉积物对卤虫幼体已产生毒性效应,其中,2、5、8三站沉积物对卤虫体长和体内SOD酶活性具有显著影响（p〈0.05）,1号和2号站沉积物对卤虫体内LDH活性有显著影响（p〈0.05）。对多个毒性效应指标运用因子分析法得到长江口南支各站因子得分F,F值大小可表征各站沉积物对卤虫综合毒性的强弱,各站F值排序为：2号（-1.59）〈5号（-0.76）〈8号（-0.42）〈1号（0.06）〈6号（0.62）〈7号（0.78）〈3号（1.31）,2号站沉积物毒性最强,3号站毒性最弱。经逐步回归分析,因子得分F与沉积物中Cu、Cd含量具有显著相关关系（R=0.91,p〈0.05）,表明长江口南支沉积物中Cu和Cd是对卤虫产生毒性效应的关键污染物。     

An assessment of contamination and ecological risk of metals in sediments of the Guaracara,Caparo and Couva rivers in Trinidad,West Indies

The presence of metals in an aquatic environment can serve as a biomarker for pollution and can be used to evaluate its contamination status. Rapid industrialisation in recent decades has propelled Trinidad and Tobago to be one of the most developed nations within the Caribbean region and has stimulated the awareness of potential ecological risks from various industrial activities affecting the rivers of Trinidad. Sediment samples from three rivers along the West coast of Trinidad were analysed for Cd, Cr, Cu, Mn, Ni, Pb and Zn. For all three rivers, the metal concentrations in sediments were in the range of 0.40–2.31?μg/g, 12.77–33.04?μg/g, 14.51–72.89?μg/g, 224.90–4472.83?μg/g, 8.20–43.08?μg/g, 22.63–38.34?μg/g and 92.0–5462.60?μg/g for Cd, Cr, Cu, Mn, Ni, Pb and Zn, respectively. Assessment of the pollution status indicated that all three rivers were considered polluted, with significant contributions from Cr, Cu, Mn, Ni and Zn. The potential ecological risk for all three rivers, however, was low and multivariate statistics revealed that mainly anthropogenic sources contributed to the metal concentrations in sediments of all three rivers.     

Metal distribution in marine sediments of the Mar Piccolo in Taranto (Ionic Sea,southern Italy)

The spatial distribution of selected metals (Fe, Ni, Mn, Zn, Cu, Pb, Hg and Cd) and their partition in the different chemical forms (speciation) were determined in benthic sediments from Mar Piccolo, Taranto (Ionic Sea, southern Italy). The aim of this study was to assess the degree of sediment contamination and bioavailability of metals, very important for Italian mussel culture, in a semi-enclosed marine ecosystem. In sediments, grain size distribution, total organic carbon (TOC), and humic (HA) and fulvic (FA) acids contents were also determined. The compounds TOC, HA and FA, in fact, have a great influence on metal complexation. High concentrations of copper, lead, zinc and mercury were found, especially in sediments of the first inlet of Mar Piccolo. Statistical analysis of results shows significant correlation among Cu, Pb and Zn concentrations and the influence of organic matter on the sediment distribution of Cu, Pb and Zn. Metal speciation analysis, carried out with sequential extraction method, shows that Fe and Ni are present in sediments mainly as sulphides. Mn and Pb are present principally in an ion-exchangeable form or bound to carbonate and Cu is associated to organic matter. Metal pollution index (MPI), calculated as a weighed mean of the metal contamination factors in each station, shows that with regard to Cu, Ni, Pb and Zn, some stations investigated are unpolluted (MPI <1), whereas in other areas, pollution level is not very high. On the contrary, for mercury, the pollution level in the first inlet of the basin is very high.     

基于响应曲面模型的多元复合体系中沉积物吸附阿特拉津的规律

文章建立了阿特拉津（AT）、铜（Cu）、镉（Cd）和马拉硫磷（Ma）四元复合体系中沉积物吸附阿特拉津的BP神经网络模型,模型训练集、验证集、预测集的均方差分别为0.070 3、0.336 0、和0.195 0,模型输入数据与其模拟值相关系数r2=0.841 6。利用所建立的BP神经网络模型构建多元复合体系中沉积物吸附AT的中心复合实验设计并绘制响应曲面模型,结果显示,响应曲面模型可以直观反映多元复合体系中各因素间影响AT吸附的交互作用,AT×Ma的交互作用最大,而除Cu×Cd外,其他两两因素之间的交互作用均呈显著效应,其中,AT×Ma、AT×Cd和Cu×Ma对阿特拉津的吸附产生协同作用,而AT×Cu和Cd×Ma则产生拮抗作用,交互作用占AT吸附量的60.28%,对阿特拉津在沉积物上的吸附影响不可忽略。     

大宝山矿水外排的环境影响:Ⅱ.农业生态系统

大宝山外排酸性矿水对周边农村地区农业生态系统具严重的负面影响，表现在：农田所用的灌溉水酸度很强，灌溉水中多种重金属含量高于国家农田灌溉水质标准，其中Cd超标约16倍；土壤严重酸化，pH值可低至3．9，总实际酸度平均达47mmol／kg，比水溶性酸度高147倍，表明由矿水带进土壤的无机酸通过土壤的缓冲作用暂时转化为非水溶态并在土壤中累积；土壤重金属含量超标，以Zn、Cu和Cd为甚；粮食和果蔬等作物重金属污染严重，其中尤以Cd最为突出，最高可超标近150倍。     

苯酚在滩涂沉积物上的吸附特性

研究了苯酚在泉州湾滩涂沉积物上的吸附行为，尤其是pH值和温度对吸附作用的影响，探讨了其吸附机理，同时绘制了吸附等温线。实验结果表明，常温下苯酚在泉州湾滩涂沉积物上的吸附平衡时间约需6h；吸附作用随pH值和温度的升高而减弱；苯酚在泉州湾滩涂沉积物上的吸附行为可以较好地用Henry、Langmuir和Freundlich型吸附等温式来描述，相比而言，Freundlich型拟合效果最好，这说明其吸附机理实际上非常复杂。     

Cd,Pb, and Cu in water and sediments and their bioaccumulation in freshwater fish of some lakes in Hanoi,Vietnam

The seasonal variations of Cd, Pb, and Cu in the water, sediments, and freshwater fish (Hypophthalmichthys molitrix, Cirrhinus molitorella, and Oreochromis mossambicus) of four lakes in Hanoi, Vietnam, were investigated. Samples for analysis were taken four times from April 2010 to March 2011. The levels in water were lower than the Vietnamese standards, except for Pb, but they were all much higher than the Canadian standards for protection of aquatic life; in the sediments, they were higher than world average levels. Bioaccumulation of the three metals in fish was site-dependent and species-dependent, but correlations of their levels in fish to those in water and sediments were weak. Levels of Pb in fish exceeded those of the UK and the WHO standards, and the recommended values of Vietnam for human consumption. Overall, the results show that the lakes are polluted with these metals, and consumption of high quantities of fish from them may be problematic. The outcome of this research helps to establish background data for future monitoring.     

广州流花湖底泥磷的垂直变化特征

广州流花湖是典型的城市景观浅水湖泊。应用经改进的Psenner连续提取法,分析了广州市流花湖底泥中各形态磷的垂直分布。结果表明,不同采样点底泥的理化性质和磷的形态垂直变化存在较大的差异;不同形态磷的质量分数由小到大的顺序是NaOH-P,Org-P,HCl-P,BD-P,NH4Cl-P,其中NaOH-P和Org-P是底泥磷的主要赋存形态,分别占底泥总磷质量的47.28%和24.23%,说明了流花湖底泥人为污染较严重;底泥生物可利用磷的质量分数在0.50～1.45 mg.g-1,平均质量分数为0.93 mg.g-1,约占总磷的58.57%,表明流花湖底泥的磷具有较好的生物可利用性,将为水体藻类大量繁殖提供潜在的有利条件。流花湖底泥中有机磷、金属结合态磷和生物可利用磷垂直方向上的分布变化规律较复杂。     

Spatial variation of phosphorus fractionation in the coral reef sediments of Lakshadweep Archipelago,Indian Ocean

Surface sediments were collected from the shore and lagoons of Kavaratti, Kadamat and Agatti islands of Lakshadweep Archipelago during May 2015 and analysed for the spatial distribution of the micronutrient element, phosphorus. Phosphorus was separated by sequential extraction procedure into five fractions – exchangeable (Ex-P), iron bound, (Fe-P), calcium bound (Ca-P), organic and residual fractions (OP) and total phosphorus (TP). The average relative contribution of each P species to TP was: OP?>?Ca –P?>?Ex – P?>?Fe – P. The high concentration of organic and residual phosphorus (87–96%) compared to inorganic phosphorus is particularly evident at stations characterised by higher total phosphorus concentrations. Among the three forms of IP in the sediments, Ca-P was dominant at all stations. The OC/OP ratio ranged from 3 to 163 in the sediments, suggesting that the organic matter in sediments had been subjected to degradation. Hence, the major contribution towards organic and residual phosphorus form is from the residual fraction comprising biologically resistant or non-available phosphorus form composed of refractory materials. The concentration of phosphorus reported in the present study is higher than that of the earlier studies in Lakshadweep, indicating a terrestrial and anthropogenic in?uence on the sediment.     

A pilot study on the effect of Cu,Zn, and Cd on the spectral curves and chlorophyll of wheat canopy at tiller stage

The aim of this study was to investigate canopy spectral reflectance responses to different levels of heavy metals copper (Cu), zinc (Zn), and cadmium (Cd) induced stress. Random blocks design experiment was conducted to simulate Cu, Zn, and Cd at five concentration levels. Chlorophyll and visible and near infrared canopy reflectance were measured for each treatment 56 days after seeding using chlorophyll meter SPAD-502 and spectroradiometer, respectively. New vegetative indices termed ratio of inclination angles (RIA), MERIS (the medium resolution imaging spectrometer) terrestrial chlorophyll index (MTCI), and normalized difference vegetation index (NDVI) were used to assess the response of canopy spectral reflectance to different heavy metal levels. Significant spectral variability especially in blue, red, and near infrared reflectance was observed for different heavy metal treatments. One-sample test showed significant difference for NDVI, MTCI, and RIA among five-level treatments at the 0.01 level. Correlation analysis demonstrated that the two vegetative indices (RIA and MTCI) were significantly correlated with chlorophyll meter values for Cd, Cu, and Zn treatments. However, NDVI was only significantly correlated with chlorophyll meter values for Cu and Zn treatments. Linear regression analysis also illustrated that RIA and MTCI were potential indices for predicting chlorophyll concentration with significant F test under Cu-, Zn-, and Cd-mediated stress.     

AVS-SEM relationships and potential bioavailability of trace metals in sediments from the Southeastern Mediterranean sea,Egypt

In risk assessment of aquatic sediments, much attention is paid to the difference between acid volatile sulfide (AVS) and simultaneously extracted metals (SEM) as indicators of metal bioavailability. Distribution of AVS and SEM (Cd, Cu, Ni, Pb and Zn) were determined in 20 representative sampling sites collected along the Egyptian Mediterranean coast. Total SEM concentration [ΣSEM] ranged from 0.012 to 0.241 μmoleg^?1. AVS concentrations were much more variable, showing significant spatial variations. The values ranged from 0.015 to 31.326 μmoleg^?1. The different relationships between AVS and SEM to establish mechanical models such as the ratio of ΣSEM and AVS [ΣSEM/AVS], the difference between the ΣSEM and AVS [ΣSEM–AVS], or the organic carbon normalised difference between SEM and AVS [ΣSEM-AVS]/f_oc models were used as parameters to evaluate potential bioavailability. Considering SEM/AVS model, sediments at the Western Harbour, Eastern Harbour, Ras El-Burr, El-Gamil East, and Port Said stations are occasionally toxic, while according to SEM-AVS model, no indication of associated adverse toxic effect would occur at any of the sampling sites. Calculated [ΣSEM-AVS]/f_oc was<130 μmoleg^?1 in the sediments indicating that sediments should pose a low risk of adverse biological effects owing to cadmium, copper, lead, nickel and zinc. Association of adverse effects to aquatic organisms was determined, using the classification of the sediments according to the Sediment Quality Guidelines (SQGs). The marine Threshold Effect Levels (TEL) and Probable Effect Levels (PEL) were used in this work and in order to obtain a more realistic measure of predicted toxicity, mean PEL quotients (PELq) were calculated. The mean PELq calculated for the sampling sites was (0.11–1.5) and categorised as slightly toxic at all stations except Baghoush, Nobarreya and western harbour, which had PELq<0.1 and categorised as non-toxic. The obtained data concluded that the remobility and bioavailability of trace metals contained in surfacial sediments of the Egyptian Mediterranean coastal area are low.     

Aliphatic and polycyclic aromatic hydrocarbon contamination in surface sediment of the Chitrapuzha River,South West India

Distribution (seasonal and spatial) of aliphatic and polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Chitrapuzha River, Cochin, India, was investigated using gas chromatography. Significantly high concentrations prevailed during the pre-monsoon season with the industrial zones of the river appearing to be hot spots with particularly elevated levels of the hydrocarbons. AHCs ranged between 7754 and 41,173?ng/g with an average of 25,256?ng/g, while total PAHs varied from 5046 to 33,087?ng/g. n-Alkane indices and PAH diagnostic ratios point to petroleum contamination in the sediments. The significance of PAHs in the sediments was explored using universally accepted interpretation tools. Observed levels of PAHs in sediments of Chitrapuzha are likely to cause adverse effects on biota.