共查询到20条相似文献，搜索用时 984 毫秒
1.
Sediment contaminant concentrations usually show an inverse correlation with grain size. This can cause difficulties in distinguishing real differences in contamination from artifacts caused by variations in sediment texture. To overcome this, regression analysis is frequently used to remove the dependency of concentrations on grain size. However, least squares regression lines can be affected markedly by the presence of a small number of unusual samples in the dataset. These outliers may represent samples which are more severely contaminated or which were derived from areas with different underlying geology. They can be removed semi-manually, but robust regression methods such as least absolute values provide a convenient and objective alternative. The methods are illustrated using an example dataset of metal contaminants in sediments from the Humber Estuary, United Kingdom. Least squares regression on the complete dataset yields a rather poor grain size normalization for several elements. By contrast, least absolute values regression produces results very similar to those obtained by least squares regression after careful manual removal of outliers, but it avoids the need for subjective judgments of which data points to omit from the analysis. The intercepts of several of the fitted regression lines were non-zero, indicating that regression-based normalization is preferable to methods based on ratios. 相似文献
2.
估算水系沉积物的地球化学背景值和识别其异常对人为污染判别与环境风险评估非常重要。采集并分析了珠江58件水系沉积物样品,经分析检验,Al、Fe和Sc被选作参考元素,并对比了确定地球化学背景及识别异常值的方法。其中,基于最小截断二乘法的回归分析是定义地球化学背景的有效方法,它是一种对异常值不敏感的稳健统计方法,而基于局部富集因子的箱线图和回归诊断图更适用于识别异常值。珠江不同河段重金属污染存在差异,北江和河网区主要受As、Cd、Cu、Pb和Zn污染,东江主要受Cu、Cr和Ni污染,而西江几乎不存在重金属污染。水系沉积物的主要污染类型是点源污染,主要污染来源是采矿和电镀等相关的工业活动。 相似文献
3.
水系沉积物中的重金属元素含量调查是矿区环境受污染程度的重要依据,同时水系沉积物的物源组成也是近年来找矿突破的重要环节之一。通过分析水系沉积物中羟基官能团与重金属游离态阳离子之间的吸附反应,结合地面实测高光谱数据,发现与重金属元素含量相关性较好的波谱波段为500~780 nm与2 100~2 300 nm,建立基于地面实测光谱技术反演水系沉积物中重金属元素含量的回归方程,最后利用反距离权重方法成功提取碾子沟-洛金洼多金属矿区3条冲沟水系沉积物中Cu、Zn等重金属元素含量。结果显示：重金属Cu和Zn模型检验精度（R2）分别为0.618和0.636;研究区内冲沟源头山地林地附近流域沉积物中的重金属含量相对中下游矿区周边农用地较低,同时沉积土壤中的重金属含量随着冲沟流向呈升高趋势。重金属含量较高的中游农用地附近应加以治理,含量异常的中下游区域为今后的找矿方向。 相似文献
4.
Heavy metal concentrations in surficial sediments from accreting and eroding areas along the coast of Guyana 总被引：1，自引：0，他引：1
5.
沉积物中的重金属元素经自然作用下可以活动态进行迁移,具有潜在生物可利用性及潜在的区域生态风险。利用近红外光谱(NIRS)技术开展不同基体类型样品响应机理研究,可为评估重金属活动态提供无损、快速的分析方法,为生态风险研究提供依据。天津七里海泻湖湿地沉积物具有低有机质-高黏土含量的特征,本文基于近红外光谱分析技术,建立了沉积物中Co、Ni、Cu、Zn、Cd、Pb重金属活动态组分含量近红外光谱-偏最小二乘回归预测模型。实验结果表明:样品在7290～6390cm~(-1)和4683～4000cm~(-1)波段存在的双羟基O—H伸缩振动、AlAl—OH及Al(Mg)—OH弯曲振动特征吸收,间接指示了重金属元素活动态含量。光谱预测结果显示,近百年来七里海沉积物中Co、Ni、Cu、Zn、Cd、Pb活动态组分的变化特征对应了当地1934—1948年、1956—1963年、1976年至今三次较明显的升温过程,也对应了1980年七里海水库建设等大型人为扰动。本研究样品中Co、Ni、Cu、Zn、Cd、Pb总量及活动态均低于国家标准中规定的生态风险阈值,七里海内村镇及周边农田来自湿地释放的重金属生态风险极低。 相似文献
6.
Chi Thanh Vu Chitsan Lin Kim Anh Nguyen Chien-Chuan Shern Yi-Ming Kuo 《Environmental Earth Sciences》2018,77(10):388
The Houjing River flows through Kaohsiung, the most industrialized city in southern Taiwan. In this study, heavy metal concentrations in water and sediments from samples along the river were investigated to illustrate metal contamination levels and call for the awareness of industrial pollution prevention. The heavy metal concentrations in the water samples were low and appear to pose little direct risk to aquatic life and irrigation, but heavy metal concentrations in the sediments are locally very high and present an environmental risk. Cadmium, Cu, and Zn were found in higher concentrations in the river sediments than those recommended in some sediment quality guidelines and findings of river sediments in similar studies worldwide. Hence, the ecological risk of heavy metal contamination in sediments was assessed using the pollution load index (PLI) and potential ecological risk index (RI). Three of the eleven sites sampled were found to have PLI values higher than 1 and 8 of them had ‘considerable’ to ‘very high’ RI values, suggesting a considerable ecological risk. These findings provide an insight into elemental metal contamination of the Houjing River and present a baseline data set, which will be critical for future development and environmental protection plans devised for the region. 相似文献
7.
Heavy metals in the Ventspils Harbour: normalization based on a multi-parameter dataset 总被引：2，自引：0，他引：2
Heavy metals were investigated in the sediments of the Ventspils Harbour located in north-west Latvia (eastern Baltic Sea). Sediment samples were analysed for major and trace metals by ICP-AES, supplemented by inorganic and organic carbon as well as grain-size distributions. Principal component analysis of the data resulted in two main parameter clusters associated with Ca- and Al-rich material and indicated differing behaviour of Pb, Cu, Zn, N and P. Normalization with respect to Ca and Al by least absolute values regression removed the spatial pattern of sediment metal content in the harbour. High residual concentrations at individual sites were associated with local contaminations, whereas the overall concentration pattern was governed by the transport of riverine fine material. Dilution with coarser, quartz-rich marine sediments led to a pronounced heavy metal concentration drop towards the harbour gates. High mixing was an important feature of sediment dynamics in the Ventspils Harbour, hampering contaminant source identification and sediment monitoring. 相似文献
8.
A. Parizanganeh B.Sc. M.Sc. Ph.D. V. C. Lakhan Ph.D. F.R.G.S. C.E.I. C.E.S. H. Jalalian Ph.D. 《International Journal of Environmental Science and Technology》2007,4(3):351-358
The nearshore marine environment of the Caspian sea is a major repository for toxic metals originating from various sources. Since the persistent toxic metals pose serious health risks this research concentrated on investigating the concentrations and spatial distribution of metals in the nearshore sediments along the Iranian coast of the Caspian sea. Fourteen sampling sites were selected along the coast and approximately 400 g of surficial sediments were obtained. Samples were sieved and three grain size fractions from each sample plus fourteen bulk samples were selected for the analysis of metals. Laboratory analysis of the samples utilized the Cold Acetic protocol, followed by Inductively coupled plasma optical emission spectroscopy. The statistical techniques were used to analyze all obtained data. Linear regression analysis demonstrated that grain size of the sediments was not a major factor controlling the concentrations and spatial distributions of heavy metals. Box and Whisker plots emphasized that metal concentrations were not homogeneously distributed. Discriminant analysis was also proved to be useful in identifying geographic areas where heavy metal concentrations occur along the coast. 相似文献
9.
Pengbao Wu Aijing Yin Xiaohui Yang Huan Zhang Manman Fan Chao Gao 《Environmental Earth Sciences》2017,76(21):745
Heavy metal contamination is of great concern in rapidly urbanizing areas. A basin-basis study on the impacts of urbanization on the heavy metal contamination in surface sediments from the Qinhuai River, Eastern China, was conducted, focusing on the spatial variation and source appointments. All of the sampling sites can be divided into three groups based on the hierarchical cluster analysis (HCA) results, which correspond well to the pollution levels of the studied heavy metals in the sediments of the rural, suburban, and urban sections of the Qinhuai River. The relationship between the heavy metal and the Al/Si ratio of sediments varied distinctly with the metal species and urbanization degree of the river sections. Correlation analysis and HCA highlighted that zinc appeared to be a fairly efficient geochemical signature of urban-related heavy metal contamination. The contributions derived from urban activities ranged from 35.9% for Ni to 96.1% for Cu, as estimated by a multilinear regression of the absolute principal component score method (MLR-ACPS). Agricultural activities had a clear impact on As, Pb, and Cu contamination of the sediment. Lithologic sources contributed a significant portion of Ni, Cr, and As to the sediment. 相似文献
10.
Hashem Abbas Madkour 《Arabian Journal of Geosciences》2013,6(6):1739-1752
In order to monitor the heavy metals effect coming from both human activities and natural inputs on coral reef environments of the Egyptian Red Sea coast, metal concentrations in thirty- eight coral reef species and nearby sediment samples collected from seven studied sites were analyzed. Four sites represent impacted areas; included from south to north Hamrawein, Safaga and Hurghada Harbours and Ras El-Behar Area. Wadi El-Gemal represents natural input area while Qola'an and Kalawye Reefs are the control areas. Heavy metal contents were measured in both coral skeletons and nearby marine sediments. Both impact areas as well as natural inputs area recorded the highest values of metals compared with the control ones. However, heavy metal contents recorded high values in sediments of Hamrawein Harbour, while coral species recorded high values in Wadi El-Gemal area. Generally, metal variations in coral reef species reflect natural conditions and human activity. On the other hand, there are no clear relationships between concentrations of heavy metals in coral reef species and those in sediments. 相似文献
11.
江苏典型地区河流沉积物重金属元素分布特征及其污染来源 总被引：3，自引：0，他引：3
通过对河流沉积物等地表沉积物中重金属元素分布等环境地球化学调查数据的统计分析,总结了江苏典型地区河流沉积物中重金属元素的分布特点与规律:江苏局部地区河流沉积物中,Cd、Pb、Zn、Cr、Cu、Ni、Hg等相对富集趋势明显,Cd最大富集倍数 100;不同河流沉积物的重金属元素分布存在差异,与其污染来源密切相关;工业排放是导致河流重金属污染的主要原因,使用含Cd的颜料作为调色剂导致部分河流出现严重Cd污染;与土壤等其他地表沉积物相比,河流沉积物中重金属元素的分布更不均衡。查明河流沉积物的重金属元素分布可为相关农产品安全性预测、确定重金属污染来源、追踪涉重产业的发展历程、防治局部耕地重金属污染等提供科学依据。 相似文献
12.
The relation between the magnitude of a flood event and the resulting environmental impacts remains unclear. This study examines
the impact of the flood of record on heavy metal deposition on the Tar River floodplain in eastern North Carolina, USA. Samples
of sediment deposited on the floodplain following Hurricane Floyd were collected from 85 sites along the lower Tar River basin
and analyzed for heavy metal concentration. The Hurricane Floyd event is the flood of record for the Tar River basin. Despite
the magnitude of the flood, little suspended sediment was deposited on the floodplain. In almost all cases the deposition
was less than 0.2 cm. There was variability in heavy metal content from site to site, but the overall concentrations were
lower than might be expected for a flood of the magnitude of Floyd. To aid in comparison of contamination levels, the heavy
metal concentrations were normalized to two environmental standards; the EPA preliminary remediation goals for residential
soil and the general background concentrations of stream sediments throughout the Tar River basin. Most samples were highly
enriched in heavy metals relative to the background concentration of stream sediments. However, samples were generally not
contaminated relative to EPA PRG regulations. Arsenic, which was significantly elevated in nearly all samples, was the only
exception. This contradiction makes it clear that the standard to which contaminants are compared must be considered carefully.
The overall low concentration of heavy metals was likely the result of smaller flooding from Hurricane Dennis, 10 days prior
to Hurricane Floyd, moving most of the stored sediment out of the basin prior to wide-spread overtopping of the banks. The
implication is that event sequencing is as important as flood magnitude when examining environmental impacts. 相似文献
13.
武汉市东湖沉积物的磁性特征与重金属含量之间的关系 总被引：6，自引：0，他引：6
对武汉市东湖主湖区的郭郑湖和塘林湖114个沉积物样品的磁化率与代表性样品的频率磁化率系数、磁滞回线参量和重金属元素进行系统分析, 综合区域环境背景, 探讨应用岩石磁性方法技术评价大型城市内陆湖泊沉积物污染程度的可行性及其效果.结果表明, 在主成分中, 郭郑湖沉积物没有一个主成分占绝对优势, 仅有少数重金属元素含量与磁化率相关, 磁化率χ与重金属富集强度的相关性较差; 而塘林湖沉积物有一个“工业源”的主成份占绝对优势, Fe (全铁)、Co、V、Mn、Ti、Ba、Cr、Ni、Cu等元素与饱和等温剩磁SIRM、χ关系密切(相关系数大于0.87).郭郑湖与塘林湖的沉积物的饱和等温剩磁与重金属富集强度的相关程度高于磁化率, 因此, 可以用其(SIRM) 作为环境污染程度的指示参量. 相似文献
14.
Maryam Ghazanfari Shabankareh Hakimeh Amanipoor Sedigheh Battaleb-Looie Javad Dravishi Khatooni 《Environmental Earth Sciences》2018,77(3):101
Heavy metal accumulation in sediments is important even at low levels due to their irresolvable character and harmful effects. Therefore, contamination of creeks, especially their sediments, is highly important for scientific communities. This study investigates the relationship between heavy metal accumulation and some physicochemical parameters of sediments (pH, EC, calcium carbonate, texture, specific gravity, density, porosity and percentage of organic matter) in a stretch of Musa Creek beaches. The results showed that the studied sediments are extremely salty and have slight variations in terms of pH. Although there are mostly clay-sized sediments in the studied area, their mineralogical composition contains calcite with smaller amounts of dolomite, aragonite and halite minerals. The correlation between each of the parameters and heavy metal concentration was modeled using OLS regression. Cr, Ni, Zn and Pb concentrations are positively correlated with each other and inversely correlated with Cd. The accumulation of heavy metals is directly related to parameters such as EC, organic matter, clay and silt, specific gravity and porosity; it is negatively related to calcium carbonate, sand and density parameters. Owing to slight variations, the pH parameter lacks any significant correlation with heavy metal concentrations. 相似文献
15.
Geochemistry of surface sediments in the Archipelago Sea,SW Finland: a multiparameter and multivariate study 总被引：1，自引：1，他引：0
This study investigates the geochemistry of soft, organic-rich brackish-water surface sediments in the Archipelago Sea (SW
Finland). The area is one of the world’s largest archipelagos, and, although it is scarcely populated, frequent ship and boat
traffic along with fish farming occurs. From 76 sites, 47 chemical elements were determined after aqua regia digestion. Other
parameters determined were grain size, water, organic and nitrogen contents. At sampling, the sediments were visually classified
into groups representing oxic, anoxic and fluctuating (intermediate) oxic seafloor conditions. The results show that the element
concentrations are quite similar to other studies in the region but with clear signs of lower anthropogenic loading. Point
source pollution was identified in one sample taken nearby a fish farm and a cable ferry. This site was strongly enriched
in Cu, Zn and Sn derived from chemicals used in either, or both, activities at the site. Overall, the sediments can be divided
into two groups that separate chemically and geographically. One group contains more fine-grained sediments that occur near
shore, while the other group contains more anoxic, organic and sulfur-rich sediments occurring more offshore. The second group
is interpreted to reflect material reworked from previous deposits as a result of shoaling of the area due to glacio-isostatic
land uplift. The visual classes were included in both partial least squares regression (PLSR) and PLS discriminant analysis.
These analyses showed that the oxic and anoxic seafloor sediments can be predicted from the chemical variables and grain-size
distribution. 相似文献
16.
A. M. Caredda A. Cristini C. Ferrara M. F. Lobina M. Baroli 《Environmental Geology》1999,38(2):91-100
We have studied sediments of the Piscinas beach (SW Sardinia, Italy), which is supplied by two streams that wash mine dumps
of abandoned lead and zinc mines at Montevecchio and Ingurtosu, situated inland from the supply basin of the beach itself.
A study of the texture, mineralogy and geochemistry of the sediments was conducted for the purpose of assessing the possible
influence of the mine waste on the composition of the sediments, looking for any anomalous enrichments in heavy metals. Furthermore,
to evaluate and quantify metal release into the sea, samples of Posidonia oceanica, a bioaccumulator marine plant, were also examined. The results indicate that the distribution of heavy metals in the foreshore
sediments is particularly affected by the contribution of the streams, while in the shoreface the distribution is affected
by the currents that disperse the sediments both out to sea and southwards. The metal contents of the Posidonia oceanica are correlated with the different stages of activity of the mines.
Received: 28 January 1998 · Accepted: 22 April 1998 相似文献
17.
Bed sediments were collected from the entire region of the Ganges basin and some parts of the Brahmaputra. In addition, selected
stations were sampled for suspended sediments as well. The samples were analysed for a number of heavy metals (Fe, Mn, Ni,
Cr, Cu, and Zn) by the thin-film energy dispersive X-ray fluorescence technique. There are pronounced temporal and spatial
variations in the heavy metals distributions. Suspended sediments are 5–10 times richer than the bed sediments. None of the
tributaries contribute significant heavy metal load, but around urban areas in Yamuna (tributary of Ganges), very high levels
due to the distribution from the drainage network are observed. Compared to the Brahmaputra, the distribution and fractionation
of heavy metals in the Ganges sediments are more erratic and highly variable. All the metals considered show high correlation
among themselves. Given the high flux of suspended sediments from the Himalayan rivers (nearly 20% of the global flux), the
worldwide budget for heavy metal transport may need to be suitably revised. 相似文献
18.
Hong-Jiao Pang Shuang-Shuang Lyu Xue-Gang Chen Ai-Min Jin Pei-Sun Loh Fei Li Yan Jiang Xian-Hui Yang Kang-Kang Yan Zhang-Hua Lou 《Environmental Earth Sciences》2017,76(17):627
In order to study the heavy metal accumulation and distribution in the roots, stems, and leaves of Spartina alterniflora, we collected S. alterniflora samples and the associated sediments along three transects at the Andong tidal flat, Hangzhou Bay. Co, Ni, Cd, Pb, Cu, and Zn were mainly accumulated in the aerial parts (stems and leaves) of the plants, and their distributions depended on their mobility and their roles during the metabolism processes of S. alterniflora. The concentrations of Cu, Zn, Cd, Hg, and Pb were significantly enhanced with the increasing of heavy metal concentrations in the sediments, while those of Co and Ni remained relatively constant. Bioaccumulation factors results showed that the serious heavy metal contamination in the sediments from the transect A may overwhelm the accumulation capability of the plants. In addition, the physicochemical properties of the sediments and the pore water therein also play a role in the heavy metal concentrations and accumulations in the plants, because they can influence the behaviors and bioavailabilities of heavy metals during nutrition and bioaccumulation processes of the plants. The sediments with vegetation did not show significantly decreased heavy metal concentration with respect to the unvegetated sediments, although the plants did absorb heavy metals from the sediments. Principal component analysis and correlation analyses indicated that Co–Ni, Cu–Cd–Hg behaved coherently during accumulation, which may be ascribed to their similar accumulation mechanisms. This work provided essential information on the heavy metal accumulation by plants in a tidal flat, which will be useful for the environmental control through phytoremediation at estuaries. 相似文献
19.
20.
Hybrid Estimation of Semivariogram Parameters 总被引：1，自引：0，他引：1
Two widely used methods of semivariogram estimation are weighted least squares estimation and maximum likelihood estimation.
The former have certain computational advantages, whereas the latter are more statistically efficient. We introduce and study
a “hybrid” semivariogram estimation procedure that combines weighted least squares estimation of the range parameter with
maximum likelihood estimation of the sill (and nugget) assuming known range, in such a way that the sill-to-range ratio in
an exponential semivariogram is estimated consistently under an infill asymptotic regime. We show empirically that such a
procedure is nearly as efficient computationally, and more efficient statistically for some parameters, than weighted least
squares estimation of all of the semivariogram’s parameters. Furthermore, we demonstrate that standard plug-in (or empirical)
spatial predictors and prediction error variances, obtained by replacing the unknown semivariogram parameters with estimates
in expressions for the ordinary kriging predictor and kriging variance, respectively, perform better when hybrid estimates
are plugged in than when weighted least squares estimates are plugged in. In view of these results and the simplicity of computing
the hybrid estimates from weighted least squares estimates, we suggest that software that currently estimates the semivariogram
by weighted least squares methods be amended to include hybrid estimation as an option. 相似文献