The use of Cerastoderma glaucum as a sentinel and bioindicator species: Take-home message

Bivalves are frequently used to assess environmental contamination, and are often considered good sentinel and/or bioindicator species. For that reason the bioaccumulation and toxicity induced by metals and As in the cockle Cerastoderma glaucum, collected from areas with different contamination levels along the Óbidos lagoon (Portugal), were used to evaluate the use of this species as sentinel and/or bioindicator. The results showed that areas in the middle of the lagoon presented lower metals and As concentrations, lower total organic matter content and lower percentage of fine particles than areas in the Bom Sucesso arm. In all areas Cr, Pb and Cu were the most abundant elements, while Ni, As, Cd and Hg were less abundant. Results also showed a moderate correlation between total elements concentrations found in C. glaucum and in sediment, and thus caution should be taken when considering this species as a good sentinel species. The present study also revealed that, in general, C. glaucum from areas in the middle of the lagoon accumulated higher concentrations of metals and As (Biota-Sediment Accumulation Factor >1) than cockles from the most polluted areas located in the Bom Sucesso arm. However, in all areas, the majority of metals (Cu, Cr, Pb) were found in cockles insoluble fraction which may explain low cellular damage and reduced oxidative stress responses observed. Therefore, our results may further alert for caution when identifying C. glaucum as a good bioindicator species. Thus, our findings highlight the fact that studies should be cautious when selecting species for environmental monitoring, since good sentinels or bioindicators in highly polluted systems may not act in the same way in low or moderately contaminated areas. Furthermore, our study warns for the misclassification of cockles in different ecosystems.     

赣江上游沉积物重金属空间分布及污染特征

为了解赣江上游表层沉积物重金属污染特征,采集赣江上游38个样品,采用电感耦合等离子体质谱仪(ICP-MS,Agilent 8800)分析沉积物中重金属含量,结合内梅罗综合污染指数法、地累积指数法、主成分分析及沉积物质量基准等研究赣江上游沉积物中重金属污染程度,分析污染物可能的来源及评价其存在的生态风险。结果表明:赣江上游沉积物中W、Cr、Mn、Cu、Zn、As、Cd、Hg、Pb等9种重金属的平均含量分别为12.30、4.40、999.84、9.72、293.81、47.66、2.85、1.34、63.68 mg·kg-1;除Cr和Cu外,其余7种重金属的平均值均超过江西省土壤背景值。内梅罗综合污染评价表明,赣江上游表层沉积物中47.37%的采样点呈严重污染,28.95%采样点污染明显,其中污染程度章水段>桃江段>贡江段;地积累指数法显示,Mn、As、W、Pb呈轻度污染,Cd和Hg呈中度或偏重度污染;主成分分析显示,As、W、Hg、Pb具有相似的污染源,Cr和Mn具有相似的污染源;沉积物质量基准分析表明,对底栖生物可能产生毒性效应的重金属主要是Cd和Hg,主要分布在章水段和桃江段。     

Distribution and assessment of heavy metals in the aquatic environment of Lake Manzala,Egypt

Analysis of trace metals from sediment and fish collected from eight locations in Lake Manzala, Egypt, during May, June and July of 2011, indicated anthropogenic impacts. The highest concentrations of metals, except Mn and Sr, were detected at Bahr Al-Baqar (S1) which drains from Cairo. At the other sampling locations, the concentrations of selected trace metals fall below the levels of concern while the geo-accumulation index (I_geo) suggests unpolluted conditions for the majority of the studied metals at most sites. However, near the Bahr Al-Baqar (S1) drain concentrations of Ag, Hg and Zn fall above the Long and Morgan's (1990) effects range low (ERL) while Pb was above their effects range median (ERM). I_geo values suggest unpolluted to moderately polluted condition for As and Sn, moderately polluted conditions for Zn, moderate to extremely polluted conditions for Ag, and severely to extremely polluted conditions for Pb at Bahr Al-Baqar. Two sites (Legan, S5, and Al-Ginka, S8) were indicated by I_geo as moderately polluted for Ag while two other sites (West of Bashar, S3, and Al Dehdy, S6) were indicated as unpolluted to moderately polluted for Ag. The Legan and Al-Ginka sites were also indicated as being moderately polluted for Zn. Similar to the sediments, the highest concentrations of metals in fish tissue were from Bahr Al-Baqar (S1). Al concentrations at all sites were comparable to concentrations known to cause lesions in fish. At all sites concentrations of selected trace metals in fish tissue were below the limits set by the FAO.     

Terrestrial isopods: useful biological indicators of urban metal pollution

Summary Environmental pollution by toxic metals is widespread in urban areas. In contrast to many industrialized sites, however, metal pollution in most urban regions occurs at low or moderately elevated levels. Reliable criteria of environmental quality have therefore to be established, with the consequence that there is an increasing need for sensitive monitoring of pollution. In this present study, the isopod species Porcellio scaber was used as a bioindicator of lead and cadmium pollution in Innsbruck, Austria. During May 1988, isopods were collected at 356 points over the whole city area; lead and cadmium in whole animals were measured using flame atomic absorption spectrophotometry. Lead and cadmium contamination of urban districts were correlated with traffic density, the only exception being higher cadmium contamination of one district in which several factories are situated. Concentrations of lead, but not of cadmium, increased along the main arterial roads with increasing traffic density and with decreasing distance from the city centre. On a large scale, concentrations of lead and cadmium increased in the direction of the prevailing wind, from south-west to north-east. On a small scale, the variability of metal concentrations can be explained by the irregular distribution of active business centres, by different degrees of contamination between exposed and non-exposed sites, and by contamination gradients depending on wind direction. Compared to highly polluted sites around industrial factories and metal smelting works, lead contamination in Innsbruck can be considered as moderately elevated, whereas cadmium contamination is low.     

湘江流域工业污染源对农田生态系统土壤动物群落影响的研究

对湘江流域工业污染区的土壤动物群落研究表明,接近污染源和污染物质富集的农田,土壤动物的种类和数量减少;工业污染区土壤的污染主要是重金属有毒物质的过量累积。调查共获得29类土壤动物,隶属于4门10纲,动物的种类与数量随着重金属污染程度的增加而递减,土壤动物密度与重金属元素Hg、Cd,zn、Cu、As、Pb的浓度密切相关,这在污染模拟实验中也得到证明。     

Metals in Tortula muralis from sandstone buildings in an urban agglomeration

Acrocarpous mosses present on stonewalls in urban areas may be used for monitoring purposes. Therefore for this investigation we selected Tortula muralis expecting that this species with an ability to colonise buildings in polluted agglomerations where other species have vanished may provide important information to monitor environmental quality. Concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V and Zn in T. muralis, in dust deposited on sandstone surfaces, and in the sandstones on which the moss grew were measured. T. muralis appeared to be a good bioindicator of airborne pollution which accumulated especially extremely high Cu, Fe and Zn concentrations reaching values much higher than harmful for plants. There was no relation between metal concentrations in underlying sandstones and T. ruralis. There was a relation between metal concentrations in dust and T. muralis. Cd, Co, Cr, Mn and V concentrations in T. muralis were higher than in dust. The Self-Organizing Feature Map identifying groups of sampling sites with similar concentrations of metals in mosses was able to classify the pollution level by distinguishing groups of highly, medium and less polluted sites. Once trained, SOFM can be applied in ecological investigations and could form a future basis for recognizing e.g. the type of pollution in urban environments by analysing the concentrations of elements in T. muralis.     

铜锈环棱螺对沉积物中重金属的生物积累及其与重金属赋存形态的关系

以铜锈环棱螺（Bellamya aeruginosa）为测试生物,采用28 d沉积物生物积累试验研究铜锈环棱螺对污染河流沉积物中重金属的生物积累,并探讨其与重金属赋存形态的关系.结果表明：铜锈环棱螺肝胰脏对Cd、Pb、Cu、Cr、Zn和Mn均具有较强的积累作用.不同重金属的积累量存在较大差别,Zn的积累量最多,占重金属总积累量的84.32%±4.36%,其次为Cu,占7.67%±2.84%;Pb、Cr和Mn的比例相对较少,分别为3.62%±1.84%、2.22%±1.03%和1.33%±0.15%;Cd所占比例最少,为0.83%±0.53%.肝胰脏中重金属元素之间的相关性均不显著.肝胰脏金属污染指数与沉积物污染综合指数具有显著的正相关关系,铜锈环棱螺可以作为沉积物重金属污染的监测生物.不同沉积物Cd、Cr、Zn和Mn的生物-沉积物积累因子（BSAF）具有较大的差异,Cu和Pb的BSAF比较稳定.Cd的生物积累与沉积物中Cd的可交换的与酸可溶态及可氧化态显著相关;Pb的生物积累与Pb的可还原态显著相关;Cu的生物积累与Cu的可氧化态显著相关;Mn的生物积累与Mn的可交换的与酸可溶态和可还原态显著相关;Cr和Mn的生物积累与其不同形态和总量均不相关.BSAF不宜作为衡量铜锈环棱螺对沉积物中重金属生物积累能力的指标.     

Fish eco-genotoxicology: Comet and micronucleus assay in fish erythrocytes as in situ biomarker of freshwater pollution

Owing to white meat production Labeo rohita have vast economic importance, but its population has been reduced drastically in River Chenab due to pollution. Atomic absorption spectrophotometry showed a merciless toxicity level of Cd, Cu, Mn, Zn, Pb, Cr, Sn and Hg. Comet assay results indicated significant (p?<?.05) DNA fragmentation in Labeo rohita as 42.21?±?2.06%, 31.26?±?2.41% and 21.84?±?2.21% DNA in comet tail, tail moment as 17.71?±?1.79, 10.30?±?1.78 and 7.81?±?1.56, olive moment as 13.58?±?1.306, 8.10?±?1.04 and 5.88?±?0.06, respectively, from three different polluted sites on the river. Micronucleus assay showed similar findings of single micronucleus induction (MN) as 50.00?±?6.30‰, double MN 14.40?±?2.56‰, while nuclear abnormalities (NA) were found as 150.00?±?2.92‰. These higher frequencies of MN induction and NA were found to be the cause of reduction of 96% of the population of this fish species in an experimental area of the River Chenab. This fish species has been found near extinction through the length of the river Chenab and few specimens in rainy seasons if restored by flood, may die in sugarcane mill season. Due to sweeping extinction Labeo rohita showed the highest sensitivity for pollution and could be used as bioindicator and DNA fragmentation in this column feeder fish species as a biomarker of the pollution load in freshwater bodies.     

Helix aspersa as sentinel of development damage for biomonitoring purpose: A validation study

Environmental health has always been threatened by the bioaccumulation of heavy metals in the terrestrial ecosystem, affecting its quality and safety. The aim of this review is to investigate the effects of heavy metal soil contamination, using the land snail Helix aspersa as a bioindicator. H. aspersa, a common species of land snail present in the area, has been used as a bioindicator of metal contamination and represents a promising ecological indicator. Various land snails species have become popular in microcosm studies because they accumulate high concentrations of certain trace metals. They express contamination as a whole through ingestion of polluted foods, such as live plants, microorganisms, soil, and water and also through cutaneous contact and from the polluted air they breathe. Land snails are considered appropriate sentinel species because trace metals tend to accumulate in their digestive gland to allow biomonitoring of metal pollution. Different experiments demonstrate that exposure in areas chronically polluted with metals, especially with lead, often causes changes in reproduction, with a variation in the mineral composition in the snail's eggs and also in its development, due to increased energy expenses associated with detoxi?cation and the excretion process.     

重金属污染可能改变稻田土壤团聚体组成及其重金属分配

采集了太湖地区污染与非污染稻田表土,采用原状土低能量分离-分散技术提取土壤团聚体粒组,分析土壤中不同粒径团聚体颗粒组质量组成和Pb、Cd、Hg、As等重金属元素的含量, 讨论重金属污染下土壤团聚体组成和重金属团聚体分配的变化.结果表明：在重金属污染下,供试水稻土砂粒级团聚体减少,而较细粒径团聚体相对增多;4种重金属元素在不同粒径团聚体颗粒组中的含量存在差异,但随粒径的变化趋势基本一致,即在<0.002 mm粒径的颗粒组中最高, 其次是0.2～2 mm粒径的颗粒组,而在0.02～0.2 mm和0.002～0.02 mm粒径的团聚体中呈现亏缺现象（富集系数为0.56～0.96）.表明重金属污染可能减弱了较大土壤团聚体的形成,导致细粒径团聚体相对增多,从而明显提高了重金属元素在粉砂和粘粒组团聚体中的分配,这可能进一步提高了污染农田重金属的水迁移和大气颗粒物迁移的风险.对于重金属污染对稻田土壤生物物理和生物化学过程的影响及其机制还需要进一步研究.     

Analysis and Human Health Risk Assessment of Arsenic,Cadmium, and Mercury in Manta Birostris (Manta Ray) Caught Along the Ghanaian Coastline

The Ghanaian marine water of the Atlantic Ocean could be said to be polluted with As and Hg. However, Cd levels do not appear to pose an environmental concern based on levels reported in tissue samples collected. Tissue samples from six Manta birostris (manta ray) used as a bioindicator were tested for these heavy metals because many people in Ghana eat this fish (aka “kako”). The pattern of bioaccumulation of these heavy metals found in the tissues of manta rays, which feed on phytoplankton, suggests that pollution has traveled deeper into the sea, which is an environmental concern and one that may require some urgent attention. Concentrations of As, Cd, and Hg were determined in kidney, liver, and muscle samples from six Manta birostris using the neutron activation analysis method. The results showed elevated levels of the metals in the manta rays. If these values are interpreted to represent daily human exposure estimates of possible human health cancer and non-cancer risks may be derived to conclude some potential risk for daily consumers of manta ray tissues. From the assessment, most of the hazard indexes for children were less than 1 except for arsenic, which was greater than 1. This means that there is for arsenic some hazard risk for children consumers of the manta ray. This is the first study to show the accumulation of heavy metals in manta ray; although the sources are not very clear, and may be due to the numerous mining activities, it needs to be investigated further. The presence of the heavy metals is very significant because the meat (muscle) is consumed in Ghana and hence there is possible accumulation in humans.     

Heavy metal accumulation in tissue/organs of a sea cucumber, Holothuria leucospilota

Holothuria leucospilota Brandt, the large black sea cucumber, is a non-selective deposit feeder, and is commonly found in the bottom of shallow waters in Hong Kong, where the sediments are often polluted with heavy metals. This study was designed to test the possibility of heavy metal accumulation by the sea cucumber at two sites in Hong Kong. Atomic absorption spectrophotometer was used to measure Cu and Zn concentrations in various tissue/organs of the animal as well as in the sediments. The result indicated that H. leucospilota accumulated zinc in the longitudinal muscle bands (97.27–98.07 ppm in dry weight) and in the respiratory tree (83.92–89.64 ppm in dry weight). Copper concentrations in these two organs were much lower than that of zinc. After the animals were kept in the aquarium without sediment for40 days, zinc concentration of the longitudinal muscle and respiratory tree decreased by 48% and 39%respectively whereas copper concentration remained unchanged. The concentrations of zinc and copper in the sediment at the two sites differed significantly but the metal level in the animals from the two sites were similar, suggesting that this sea cucumber was not an ideal bioindicator of heavy metal pollution in the sediment. This revised version was published online in August 2006 with corrections to the Cover Date.     

Examination of the bioindicator potential of Oncholaimus campylocercoides (Oncholaimidae,Nematoda) from Bizerte bay (Tunisia)

We have tested the use of the free-living nematode Oncholaimus campylocercoides as a bioindicator of petroleum pollution. This was analysed using a polluted-reference sampling strategy for one year in Bizerte bay (Tunisia). We noted a decrease in body dimensions together with many biometric anomalies when organisms are exposed to petroleum compounds. The three first moults and the egg-production phase of specimens of O. campylocercoides from the polluted site TRIC (Tunisian Refining Industries Company) took longer. The egg volume was negatively affected by pollution and the development from egg to juveniles J1 in one side and from juveniles J4 to males from TRIC beach on another side seems to be faster.Our results demonstrated that biometry, life cycle and fecundity are useful indices to biomonitor hydrocarbon pollution in marine ecosystems. Juveniles of the second and third stage and gravid females of O. campylocercoides seem to be the most appropriate bioindicators.     

Influence of some metal concentrations on the activity of antioxidant enzymes and concentrations of vitamin E and SH-groups in the digestive gland and gills of the freshwater bivalve Unio tumidus from the Serbian part of Sava River

We examined whether the freshwater bivalve Unio tumidus from the Sava River can serve as a bioindicator organism for long-term biomonitoring of river ecosystems for the presence of metal pollutants. To this end, we assessed in the digestive glands and gills of mussels, changes in activity of antioxidant enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR), the phase II biotransformation enzyme glutathione-S-transferase (GST)), and changes in the concentrations of the non-enzymatic components of the antioxidant system (vitamin E and sulfhydryl groups (-SH), after exposure to metals in the environment. Mussels were collected at four sites where the concentrations of dissolved metals (Cu, Cd, Zn, Fe, Mn, Hg, Ni, As, Pb) were quantified. Cu, Ni and As exerted concentration-dependent inhibitory effects on CAT and GST activities. Increasing concentrations of Cd promoted increases in GSH-Px activity and -SH concentration. In response to increased Zn concentration GR activity increased whereas Fe promoted decreased enzymatic activity. Negative correlations between the concentrations of Cu and Cd and vitamin E, and a positive correlation between Mn and vitamin E concentrations were detected. The described correlations between components of the antioxidant system and metal levels in the environment reveal a high physiological sensitivity of freshwater mussels to pollution, supporting their use in biomonitoring of metal contamination in river ecosystems.     

First Description of Various Bacteria Resistant to Heavy Metals and Antibiotics Isolated from Polluted Sites in Tunisia

Environmental bacteria belonging to various families were isolated from polluted water collected from ten different sites in Tunisia. Sites were chosen near industrial and urban areas known for their high degree of pollution. The aim of this study was to investigate cross-resistance between heavy metals (HM), i.e., silver, mercury and copper (Ag, Hg, and Cu), and antibiotics. In an initial screening, 80 isolates were selected on ampicillin, and 39 isolates, retained for further analysis, could grow on a Tris-buffered mineral medium with gluconate as carbon source. Isolates were identified based on their 16S rRNA gene sequence. Results showed the prevalence of antibiotic resistance genes, especially all isolates harbored the bla_TEM gene. Some of them (15.38%) harbored bla_SHV. Moreover, several were even ESBLs and MBLs-producers, which can threaten the human health. On the other hand, 92.30%, 56.41%, and 51.28% of the isolates harbored the heavy metals resistance genes silE, cusA, and merA, respectively. These genes confer resistance to silver, copper, and mercury. A cross-resistance between antibiotics and heavy metals was detected in 97.43% of our isolates.     

Application of in situ cage cultures of phytoplankton for monitoring heavy metal pollution in two Norwegian fjords

A simple apparatus for in situ use of the cage culture technique for growing planktonic algae has been developed and used to follow growth and metal uptake of three diatoms in two Norwegian fjords polluted by heavy metals. Continuous pumping of sea water through a chelating resin and continuous water sampling was used to obtain average values for dissolved and particulate heavy metal content at the various test sites. The metals investigated (zinc, copper, lead, cadmium, and mercury) showed differences in the proportion of dissolved to particulate fractions.The three species of diatoms tested gave systematic growth responses to heavy metal pollution in the moderately polluted fjord; one alga died, one showed reduced growth rate at the more contaminated site compared with those at less polluted sites, while the most tolerant alga was apparently not affected. In the heavily polluted fjord only the most tolerant alga survived, showing decreasing growth rate with increasing pollution.Uptake of heavy metals increased generally with increasing heavy metal content in the sea water. The contents in the algae grown in the most polluted fjord were much higher than those obtained in the less polluted fjord, which were higher than the contents reported for algae from non-contaminated areas.     

The activity of glutathione S-transferase in hepatopancreas of Procambarus clarkii: Seasonal variations and the influence of environmental pollutants

• 1.1The glutathione S-transferase activity in hepatopancreas of the American red crayfish Procambarus clarkii after 15 days' acclimatization in tap water aquaria was measured in specimens collected monthly for a whole year, and shows seasonal variation.
• 2.2. Previous data on the environmental pollution of Lake Albufera suggest a possible correlation with the activity tested in the different seasons of the year considering the results of non-acclimatized animals.

     

Ecogenotoxicological studies for an early toxicity screening and monitoring in Epinephalus chlorostigma and Scamberomorus commerson

The study was planned to investigate DNA fragmentation in fish to screen aquatic toxicity and in Epinephalus chlorostigma and Scamberomorus commerson collected from Red sea near Jizan, Saudi Arabia from three locations “(Corniche North park: “16.92161, 42.54631; Jizan Port: 16.874, 42.54952” N and Jizan Economic City: 17.26589, 42.34738“ ”)“ were used as a case study for the application of comet assay. The study area of the Red Sea is polluted due to anthropogenic activities and the disposal of wastes from multiple sources. Comet and micronucleus assays were used to detect genotoxicity in these fish species harvested from three sites. The concentration of Pb, Cr, Zn, Mn, Cu, Cd, Sn, and Hg was higher in the water samples collected from the polluted site compared to the non-polluted site of the Red sea. Comet assay for S. commerson showed significant (p < 0.05) genetic damage about 44.33 ± 3.03% DNA in comet tail at site S1. It was subsequently reduced to 31.71 ± 3.52% and 22.11 ± 2.52% at sites S2 and S3. E. chlorostigma also showed significant DNA in comet tail as 17.34 ± 2.19%, 11.87 ± 3.01%, and 36.41 ± 3.98% at site S1-S3, respectively. Significant (p < 0.05) DNA damage was observed in the fishes procured from non-polluted locations and upstream locations. The micronucleus induction in E. chlorostigma was recorded as 23.20 ± 4.19 and 2.20 ± 0.58%, respectively, non-polluted and polluted sites. S. commerson exhibited significant differences between polluted and non-polluted sites (44.80 ± 3.73 and 8.20 ± 2.20‰) polluted and upstream (44.80 ± 3.73 and 20.60 ± 4.02‰), respectively. A significant difference was obtained between E. chlorostigma and S. commerson for nuclear abnormalities S. commerson showed higher frequencies for nuclear deformities than E. chlorostigma. S. commerson showed substantial micronucleus induction frequencies collected from an area of low pollution intensity (upstream). This study showed that E. clorostigma and S. commerson could be successfully used as a bioindicator to determine the health of the Red Sea through the most specific assays such as comet and micronucleus tests as an early warning and to devise the monitoring strategies to ensure a safe supply of fish for human consumption.     

Monitoring pollution in Tunisian coasts: application of a classification scale based on biochemical markers

Over the past decade, molecular, biochemical and cellular markers have been extensively used in pollution monitoring of aquatic environments. Biochemical markers have been selected among early molecular events occurring in the toxicological mechanisms of main contaminants. This paper assesses the marine environment quality along the Tunisian coasts using a statistical approach. Clams (Ruditapes decussatus) were collected during the four seasons of 2003 on seven different sites from the Tunisian coasts. Oxidative stress was evaluated in gills using catalase activity (Cat), neutral lipids and malonedialdehyde accumulation. Glutathione S-transferase activity is related to the conjugation of organic compounds and was evaluated in both, gills and digestive glands. Acetylcholinesterase activity was evaluated as the biomarker of exposure to organophosphorous, carbamate pesticides and heavy metals. For each biomarker, a discriminatory factor was calculated and a response index allocated. For each site, a global response index was calculated as the sum of the response index of each biomarker. Discriminant analysis shows significant differences between sites and seasons compared with control sample. Faroua (site 1) and Menzel Jemile (site 2) seem to be the less polluted with respect to the other sites for all seasons. Gargour (site 6) shows the highest Multimarker Pollution Index during the four seasons, indicating higher contamination level.     

Contamination and spatial distribution of heavy metals in soil of Xiangxi River water-level-fluctuating zone of the Three Gorges Reservoir,China

The Three Gorges Reservoir is the largest hydroelectric project in China. It forms water-level-fluctuating (WLF) zones with a water level difference which can reach 30 m and a total area of 349 km² along the Yangtze River. To determine the pollution level and spatial distribution of heavy metals in WLF regions, Xiangxi River (XXR), the largest first-order tributary, was selected as the study area. Both single-factor and multi-factor evaluation methods were employed to assess the contamination indices of heavy metals in soil. The results showed that the pollution degree for sampling sites varied from slight to moderate pollution levels, where 64% were in slight pollution degree and 4% were in moderate pollution degree. Approximately 68% of the sites were polluted. The ranking of 6 different kinds of heavy metals according to pollution degree was Cd > Pb > Cr > Hg > Ni > Cu. While Cd and Pb contributed the most to the pollutions, the contributions of the other four remained minor. Furthermore, a spatial distribution map of the comprehensive contamination index for the XXR basin is generated. The concentrations of heavy metals in sediments along 4 transects showed an overall decreasing trend with increasing elevation.