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1.
Mining and milling of metal ores coupled with industries have bequeathed many countries the legacy of wide distribution of metal contaminants in sediments. The aim of this study was to assess potential sediment contamination via useful screening methods (XRF, CHNS, TGA/MS). The sediments were collected from the water reservoir Krompachy Eastern Slovakia in April 2015. Within the frame of evaluation it was found that the concentrations of the study elements (Cu, Zn, As, Pb, Cr, Ni, Cd) exceeded some of the MPC, TV and IV values. Sample c was the most polluted by metals, which evident according to it’s the highest CHNS proportion as well as the highest clay and silt proportion. In the samples studied the best correlation was confirmed between weight losses in the temperature range (400–620 °C) and the following metal concentrations: Cu (r = 0.89), Zn (r = 0.88), As (r = 0.93), Hg (r = 0.83), Pb (r = 0.87). The greatest proportions of m/z 44, m/z 18 were detected at temperatures (400–620 °C) associated with decomposition of minerals such as siderite, barite, and exothermic loss of more refractory aromatic C took also place.  相似文献   

2.
The West Development Program, initiated in 2000 by the central government of China, has attracted huge investments in the arid and semiarid regions of northwest China. As a consequence of this development, environmental pollution and ecological degradation have been widely reported. The Silk Road economic belt proposed by China promotes further economic development in the regions, but rational planning and regular monitoring are essential to minimize any additional negative impacts of the anthropogenic activities. This article reports an investigation on the distribution, enrichment and sources of trace metals in the topsoil in and around the Ningxia Hengli Steel Wire Plant (HSWP) situated along the Silk Road economic belt. The concentrations of Cd, Pb, Cr, Cu, Zn, Ni, Mn, V and Co in the surface soils of the study area vary, respectively, in the following ranges: 0.083–18.600, 21.9–2681.0, 58.0–100.0, 14.6–169.9, 59.0–4207.3, 19.3–40.8, 411–711, 55.2–76.6 and 7.46–25.21 mg/kg. The concentrations of Cd, Pb, Cr, Cu, Zn and Co are significantly higher than their local background values. Pollution levels of these trace metals in the surface soils were assessed using contamination index (C f i ), geo-accumulation index (I geo), modified contamination degree (mC d) and pollution load index. The potential ecological risks caused by the metal pollution were assessed by means of potential ecological risk factor (E f i ) and potential ecological risk index. The Spearman correlation and cluster analysis were applied to determine the contamination sources. The HSWP zone, associated with very high potential ecological risk caused by Pb and Cd, is more seriously contaminated by trace metals than the residential zone. This study indicates that Cd, Pb, Cu, Zn and Co mainly originate from industrial pollution, whereas Cr, Mn, Ni and V result from both industrial activities and natural processes.  相似文献   

3.
This research is focused on evaluating heavy metals (Cd, Cu, Fe, Mn, Pb, and Zn) uptake and removal by Eleocharis ovata, Cyperus manimae, Typha dominguensis, and Pteridium aquilinum in a natural wetland impacted by mining activities. We analyzed heavy metals content and distribution in native plants, soils, and water of a semipermanent natural wetland in Taxco de Alarcón, Guerrero, and we also determined the physicochemical characteristics of the water. Translocation factor (TF) and bioconcentration factor (BCF) were evaluated. Results showed that physical and chemical conditions are favorable for plants development. Correlation analysis showed a good and positive relation (0.95) between Cu and Pb in soils and plants. In the analyzed matrices: Zn (0.62–2.20 mg/L) exceeded the permissible limits in water, high concentrations of Pb and Zn (26.57–525.67 and 266.67–983.33 mg/kg, respectively) were detected in the studied soils, and Pb exceeded the normal range for E. ovata and P. aquilinum in the analyzed plants. Uptake of heavy metals in the tissues of different species was found in the following order: root > leaf. Data of TF and BCF showed that E. ovata is a tolerant plant with respect to heavy metals exposure since TF value was greater than 1. This study showed that E. ovata could be considered as a bioaccumulator of heavy metals in contaminated soils.  相似文献   

4.
The technique of diffusive gradients in thin films (DGT) was applied to obtain high-resolution vertical profiles of trace metals in sediment porewater of a eutrophic lake, Lake Chaohu. All sampling sediments were under anaerobic conditions with Eh values below 0, the redox potential profile in M4 was relatively stable, and higher Eh values in M4 than that in M1 were observed due to hydrodynamic effects. Fe, Mn and As exhibited closely corresponding profiles due to the co-release of Fe and Mn oxides and the reduction of As. Higher Fe and Mn concentrations and lower As concentrations were observed in M1 of the western half-lake than those in M4 of the eastern half-lake due to different sources and metal contamination levels in the two regions. Cu and Zn showed increasing concentrations similar to Mn and Fe at 1–2 cm depth of sediments, while DGT measured Co, Ni, Cd and Pb concentrations decreased down to 3–4 cm in the profiles. Co, Ni, Cu, Zn, Cd and Pb showed insignificant regional concentration variances in the western and eastern half-lakes. According to the R(C DGT/C centrifugation) values, the rank order of metal labilities decrease as follows: Fe (>1) > Cu, Pb, Zn (>0.9) > Co, Ni, Cd (>0.3) > Mn, As (>0.1).  相似文献   

5.
Multidimensional assessment of air pollution was carried out on trace metals in particulates, desert plant parts and soil collected from the six sites to validate air pollution tolerance index, translocation and bioaccumulation factors. A map indicating the sampled sites was superimposed on the Disper 5.2 software graphical interface to track the particulate dispersion route during the summer and winter seasons. This study showed site-wise orientation of particulates dispersed in the ambient air. Observations indicated the high concentrations of dispersed coarse > fine > ultra-fine particulates in trace metals analyzed from selected desert plants and in the soil especially during winter than in the summer seasons. High air pollution tolerance index was observed in the sequence of Calatropis gigantean > Portulaca oleracea > Citrullus collocynthis > Rumex vesicarius > Bienertia sinuspersici > Tribulus terrestris. Assessment of translocation and bioaccumulation factors labeled these desert plants as hyper-accumulators. The synergistic effect of the translocation and bioaccumulation factor in the various plants and the pollution levels for a given geographical location provides insight management to mitigate air pollution and landscape designers to grow tolerant species and protect sensitive plants from air pollution.  相似文献   

6.
In the present study, roadside-deposited sediment samples collected from Kuwait city district, in Kuwait, were analyzed for specific heavy metals (As, Cr, Cu, Mn, Ni, Pb, and Zn). Contamination assessment status of heavy metals in roadside sediments was made using mathematical models in terms of enrichment factor (EF), geoaccumulation index (I geo), and contamination factor (CF). The sediments showed remarkably high levels of all the metals, except Ni, above background concentrations in the following order (As, Cu, Pb, Zn, Mn, and Cr). CF and I geo revealed overall moderately uncontaminated and moderate contamination, respectively, but the EFs for all metals ranged between moderate and significant enrichment.  相似文献   

7.
There is currently limited research available on the secondary metabolites of moulds in workplaces. The aim of this study was to determine the mould contamination in museums (N = 4), composting plants (N = 4) and tanneries (N = 4) and the secondary metabolite profiles of Alternaria, Aspergillus and Penicillium isolates from these workplaces. Alternaria, Aspergillus and Penicillium species were identified using the ITS1/2 sequence of the rDNA region. Mould metabolites were quantitatively analysed on standard laboratory medium and mineral medium containing materials specific to each workplace using liquid chromatography-mass spectrometry. We also examined the cytotoxicity of the moulds using MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assays. Air microbiological contamination analyses showed a number of microorganisms, ranging from 2.4 × 103 CFU m?3 (composting plants) to 6.8 × 104 CFU m?3 (tanneries). We identified high percentages of Alternaria, Aspergillus and Penicillium moulds (air 57–59%, surfaces 10–65%) in all workplaces. The following moulds were the most cytotoxic (>90%): Alternaria alternata, A. limoniasperae, Aspergillus flavus, Penicillium biourgeianum, P. commune and P. spinulosum. The same mould species isolated from different working environments exhibited varying toxigenic and cytotoxic properties. Modifying the culture medium to simulate environmental conditions most often resulted in the inhibition of secondary metabolite production. Moulds isolated from the working environments produced the following mycotoxins (ng g?1): chanoclavines (0.28–204), cyclopiazonic acid (27.1–1045), fumigaclavines (0.33–10,640,000), meleagrin (0.57–13,393), roquefortins (0.01–16,660), rugulovasines (112–220), viridicatin (0.12–957), viridicatol (4.23–2753) and quinocitrinines (0.07–1104), which may have a negative impact on human health.  相似文献   

8.
Past mining activities in Swaziland have left a legacy of abandoned mine sites (iron ore, asbestos, diamond and coal mine dumps), all of which have not been reclaimed. These sites were recently (2013) considered by the country’s wastewater treatment authorities as suitable places where biosolids can be applied, firstly as a biosolids disposal alternative and, secondly, as a strategy to accelerate mine soil remediation through phytostabilization. In order to understand the effects that this might have on mine soil conditions and microbiota, two (2) plant growth trials were conducted in biosolid-treated iron mine soils and one (1) trial on undisturbed soil, under greenhouse conditions, for twelve (12) weeks. According to the results obtained, the combination of biosolids and plants led to significant improvements (p < 0.05) in parameters related to soil fertility. Significant increases (p < 0.05) in alkaline phosphatase, β-glucosidase and urease soil enzyme activities were also observed. Copper and zinc were significantly (p < 0.05) increased (Cu from 17.00–50.13 mg kg?1; Zn from 7.59–96.03 mg kg?1); however, these sludge-derived metals did not affect enzyme activities. Improvements in soil physicochemical conditions, organic matter–metal complexes, effects of plants on metals and the essentiality of Cu and Zn to soil enzymes were thought to have masked the effects of metals. Increases in soil enzyme activities were considered to be indicative of improvements in the quality, fertility health and self-purification capacity of iron mine soils due to synergistic effects of biosolids and plants.  相似文献   

9.
Heavy metals are introduced in human tissue through breathing air, food chain and human skin. They can cause damage to the nervous system and internal organs. In the present study, sixty street dust samples were collected from the central area of Tehran and were digested in the laboratory to determine the content of Zn, Ni, Cd, Cr, Cu and Pb, using inductively coupled plasma optical emission spectrometry (ICP-OES). The level of contamination with the analyzed metals was determined according to the following indices: geo-accumulation index (I geo), enrichment factor (EF), pollution index (PI), integrated pollution index (IPI) and potential ecological risk index (RI). The average concentration of heavy metals found was in the order of Zn > Cu > Pb > Ni > Cr > Cd. The average I geo values for Cd, Cr, Cu, Ni, Pb and Zn were 1.53, ?1.88, 2.68, ?0.67, 1.62 and 2.70, respectively. Among the investigated heavy metals, zinc and copper had the maximum average EF values and were placed into the “very severe enrichment” class. Potential ecological risk factor (E r) also indicated that Cd had the highest risk, and it was classified as of considerable potential ecological risk. Therefore, it is necessary to pay more attention to the appearance of Cd in the human environment. The calculated potential ecological risk index values also illustrated that the street dust samples presented a “moderate ecological risk.” The calculated IPI values showed that the pollution levels of the street dust samples ranged from high to extremely high.  相似文献   

10.
The first data on ecology and trace metal (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb) bioaccumulation by macrozoobenthic organisms in area along the 130°E meridional transect from shallow water near the Lena River’s delta till the 78°N are presented. At the newly discovered methane seeps in the shallow Laptev Sea areas (72 m depth), a higher total abundance and biomass compared with background stations were recorded. In carbonate shells and soft tissues of Bivalvia Portlandia arctica and Astarte borealis, the high concentrations of Mn, Fe, Pb, Ni and Co were detected that varied in dependence from sampling site. In the dominating taxa of brittle stars (Ophiuroidea), there were found no significant differences between majority of trace metal content in organisms inhabiting the seeps area and background ones. An elevated content of some metals was detected in the Asteroidea bodies that may be attributed to its trophic behavior (deposit feeder).  相似文献   

11.
In the present study, bulk contents of Ni, Zn, Cu, Pb and Mn in urban area of Tehran city are determined. Subsequently, the chemical bonds of metals with various soil fractions are brought out. Chemical partitioning studies revealed that various percentile of Ni, Zn, Cu, Pb and Mn is found in anthropogenic portion of soils. Zinc, Ni, Cu, Pb and Mn fall within “low pollution” class in accordance with index of pollution (I POLL). The trend of anthropogenic share of studied metals in soils of Tehran is Zn (55 %) > Cu (31 %) > Ni and Pb (30 %) > Mn (12 %). The overall potential of studied plants in metal removal from soil is Salvia > Viola > Portulaca. It should be pointed out that roots have higher potential in metal removal from soil when compared with leaf and stem. Lithogenic portion of metals remains intact before and after pot analysis. Thus, phytoremediation is highly dependent on the chemical bonds of metals. Present study showed that metal contents of loosely bonded ions, sulfide bonds and organometallic bonds are reduced after 90 days of plant cultivation. The overall removal trend of studied metals is Zn (16 %) > Cu (14 %) > Ni (11 %) > Pb (7 %) > Mn (6 %). The obtained results show that the anthropogenic portion of metals is reduced after the phytoremediation practice. For instance, the initial anthropogenic portion of Zn (55 %) is changed to 39 % showing an overall reduction of about 16 %. The anthropogenic portions of Cu, Ni, Pb and Mn are also reduced by 14, 11, 7 and 6 %, respectively.  相似文献   

12.
Landfill leachate is a high-strength wastewater. If it is not managed properly, it can pollute surrounding environment. The aim of this study is to determine the simultaneous adsorption capacity of iron oxide-coated gravel for metals such as Cd(II), Cu(II), Fe(II), Ni(II) and Zn(II) in high-strength leachate sample. Different operating conditions such as pH, time, and dosages were investigated to determine the kinetics and mechanism of adsorption process. Coating with iron oxide changed the external surface of gravel. The adsorption capacities increased with increased pH, and the optimum pH was found to be 7. High removal rates were observed in a short period of time. The Freundlich model fitted reasonably well to the experimental data, indicating multilayer adsorption process and the heterogeneity of the surface (R 2 ranging 0.57–0.94). The Temkin model fitted well to the experimental data as well (R 2 ranging 0.67–0.98), indicating that the adsorption is an exothermic process. The adsorption of ions was found to obey second-order kinetics, indicating one-step, surface-only adsorption process. The degree of metal adsorption on iron oxide-coated gravel at pH 7 was in the order Cu(II) > Cd(II) > Fe(II) > Zn(II) > Ni(II).  相似文献   

13.
Heavy metals are known to pose a potential threat to terrestrial and aquatic flora and fauna. Due to increasing human influence, heavy metal concentrations are rising in many mangrove ecosystems. Therefore, an assessment of heavy metal (Cd, Cr, Cu, Ni, Pb, Fe, Mn, and Zn) concentrations was conducted within the bulk soil and rhizosphere soil of Avicennia marina at the Pichavaram Mangrove Forest in India. The rhizosphere soil showed higher concentrations of metals than the bulk soil. Compared to the bulk soil, the metals Cd, Fe, Mn, and Zn were 6.0–16.7% higher, whereas Cr, Cu, Ni, and Pb were 1.7–2.8% higher concentration. Among the three selected sampling sites (dense mangrove forest, estuarine region, and sea region), the sea region had the highest concentration of all heavy metals except Zn. The trend of the mean metal concentration was Fe > Mn > Cr > Ni > Cu > Pb > Zn > Cd. Heavy metals concentrations elevated by the 2004 tsunami were persistent even after 4 years, due to sedimentary soil processes, the rhizosphere effect of mangroves, and anthropogenic deposition. Analysis of the heavy metal-resistant bacteria showed highest bacterial count for Cr-resistant bacteria and rhizosphere soil. The maximum level of heavy metal-resistant bacteria was observed at the site with the highest heavy metal contamination. The heavy metal-resistant bacteria can be used as indicator of heavy metal pollution and furthermore in bioremediation.  相似文献   

14.
The strong adaptability of Broussonetia papyrifera (L.) Vent. to low phosphorus (P) conditions can be attributed to the large amount of root-exuded organic acids and the high efficiency of P extraction. However, microelement contents are influenced by low-P stress, and their effects on the photosynthetic capability of B. papyrifera remain unknown. In this study, we investigated the effects of low-P treatment on net photosynthetic rate (P N); chlorophyll a fluorescence (ChlF) characteristics; and Fe, Mn, Cu, and Zn contents of B. papyrifera and Morus alba L. seedlings. Results show that B. papyrifera exhibited better photosynthetic capability under moderate P deficiency (0.125, 0.063, and 0.031 mmol/L P treatments), whereas the photosynthetic capability of M. alba decreased under moderate and severe P deficiency (0.016 and 0 mmol/L P treatments). Under moderate P deficiency, the decrease in Cu and Zn contents in B. papyrifera was lower than that in M. alba. Under severe P deficiency, a considerable decrease of photosynthetic capability in B. papyrifera and M. alba was associated with low Cu and Zn contents. The P N of the two Moraceae species exhibited a better correlation with Cu and Zn contents than with Fe or Mn content. P deficiency could not only decrease cyclic photophorylation and photosynthetic efficiency, but could also affect the stability of thylakoid membrane structure and electron transport efficiency by influencing the contents of Cu or Zn, thereby affecting photosynthesis.  相似文献   

15.
The accumulation efficiency of selected trace elements in the leaves of Melandrium album and Robinia pseudoacacia grown on heavy metal contaminated sites in comparison with a non-contaminated one was evaluated. The study was undertaken to calculate air pollution tolerance index and to determine the contents of selected metabolites: glutathione, non-protein thiols, ascorbic acid, chlorophyll and the activity of antioxidant enzymes: guaiacol peroxidase and superoxide dismutase. Such estimations can be useful in better understanding of plants defense strategies and potential to grow in contaminated environments. The results in the most contaminated site revealed higher contents of metals in M. album leaves, especially Zn, Cd and Pb (3.4, 6 and 2.3 times higher, respectively) in comparison with the R. pseudoacacia. Better accumulation capacity found in M. album was shown by metal accumulation index values. The plants could be used as indicators of Zn, Cd (both species) and Pb (M. album) in the soil. Glutathione content (in both species) and peroxidase activity (in M. album), general markers of heavy metals contamination, were increased in contaminated sites. In most cases in contaminated areas R. pseudoacacia had decreased ascorbic acid and chlorophyll levels. Opposite tendency was recorded in M. album leaves, where similar or higher contents of the above-mentioned metabolites were found. In our study, M. album and R. pseudoacacia proved to be sensitive species with the air pollution tolerance index lower than 11 and can be recommended as bioindicators.  相似文献   

16.
With the increasing industrialization, heavy metals concentration in soils has greatly increased. Phytoremediation is a low-cost, non-intrusive and aesthetically harmonious technology that uses plants to remediate contaminated sites by heavy metals. The aim of the study was to determine Cd, Pb and Zn concentration in the biomass of plant species growing on a multi-metal-contaminated site of lead smelter processing, to assess the workability of using these plants for phytoremediation purposes and highlight possible damage in morphological leaf changes. Two plant species, i.e., Ipomoea asarifolia and Urochloa decumbens and the associated soil samples were collected and analyzed Cd, Pb and Zn concentrations and then calculating the bioconcentration factor and translocation factor parameters for each element. Leaves and roots samples were observed by light microscopy. Metal concentrations varied greatly and majorly depend on site sampled, plant species and tissue. Cd, Pb and Zn in tissue ranged from 0 to 102.48, 0 to 381.04 and 12.84 to 295.02 mg Kg?1. However, none of the plant showed potential for hyperaccumulation. Both plants showed bioaccumulation factor more than one, where it was 7.66 and 6.82 for Pb and Zn in U. decumbens, respectively. Translocation factor was calculated below one for both plants and all metals. Morphological studies revealed development of adaptive features that strengthen the U. decumbens to grow in contaminated soil. Our study suggests that I. asarifolia and U. decumbens have potential for phytostabilization at multi-metal-contaminated site.  相似文献   

17.
Contamination with heavy metals in surface and groundwater is a threat to human health and ecosystems. Due to this, the need arises to remediate water polluted through ecological and profitable technologies, such as phytoremediation. The objective of the work was to evaluate the concentration of lead (Pb) and zinc (Zn) in the floating macrophytes Limnobium laevigatum and Ludwigia peploides, after being exposed to contaminated water experimentally. In this way to be able to determine if these plants have mechanisms that allow them to accumulate the metals in the roots and to perform the translocation of these to different vegetative organs, L. laevigatum and L. peploides were placed in solutions contaminated with Pb ([Pb]?=?5 mg/l) and Zn ([Zn]?=?20 mg/l). The concentrations of metals in water, root and leaf samples were evaluated as a function of time (0, 1, 2 and 4 days). The determination of the metals was performed by the atomic absorption spectrophotometry technique. After 4 days of exposure to Pb and Zn, the plants showed high metal removal efficiencies of water, more to 70% in all cases. Pb was accumulated fundamentally by roots, while Zn was accumulated more in the leaves. In addition, the bioconcentration and translocation factors for each metal were calculated.  相似文献   

18.
Concentrations of Pb and Zn, plant uptake of these metals, the influence of the plants’ growth on the physicochemical properties and metal concentrations in the tailings of an abandoned 300-year-old mine tailing dam in Zacatecas, Mexico were investigated. Tailings were found to be heavily contaminated, with average levels of 2621 ± 53 and 3827 ± 83 mg/kg for Pb and Zn, respectively (maximum concentrations of 8466 ± 116 and 12,475 ± 324 mg/kg, respectively), exceeding international standards. Though physico-chemical conditions (pH, conductivity, redox potential, moisture, organic matter, nitrate, nitrite, ammonium nitrogen, total nitrogen, phosphorus and sulfates) do not favor the development of vegetation, some plants have adapted to these adverse conditions. Moreover, there was a significant reduction of Pb and Zn concentration in the rhizosphere (between 10–78% for Pb and 18–62% for Zn, depending on plant species). Sporobolus airoides showed average biomass concentrations of 173 ± 2 and 313 ± 6 mg/kg, for Pb and Zn, respectively; which implies a risk for mobility and possible incorporation into the food chain. Barcleyanthus salicifolius, Asclepsias linaria and Cortaderia selloana on the other hand, showed average biomass concentrations of 28 ± 3 and 121 ± 5 mg/kg of Pb and Zn, respectively, thus representing a lower biomagnification risk. The effect of these plants to reduce metal concentrations in the rhizosphere, improve physico-chemical conditions in metal polluted substrates, but with limited metal accumulation in biomass, suggests that they can be evaluated for use in stabilizing metal polluted tailings.  相似文献   

19.
The use of agricultural wastes as biosorbents is gaining importance in bioremediation of heavy metal-polluted water and soils, due to their effectiveness and low cost. This work assesses the Cd, Pb and Cu adsorption capacity of the raw materials used in the production of substrates for mushroom production (Agaricus bisporus and Pleurotus ostreatus) and the spent mushroom composted (SMC), based on the functional groups of their organic carbon. The raw materials studied included agricultural wastes (wheat straw, wheat and rice poultry litter, grape pomace) and inorganic substances (gypsum and calcareous sand). Organic carbon from wastes and their composting products were characterized by CP-MAS 13C NMR. Langmuir adsorption isotherms of metals were plotted for each raw material, composting step, spent A. bisporus and P. ostreatus substrates and the final SMC. The maximum adsorption capacities of SMC were 40.43, 15.16 and 36.2 mg g?1 for Cd, Pb and Cu, respectively. The composting process modified the adsorption properties of raw materials because of the enhanced adsorption of Cd and Cu and decreased adsorption capacity of Pb. CP-MAS 13C NMR and potentiometric titration were used to identify the functional groups of the organic carbon responsible for the metal adsorption. The content of cellulose was correlated with Pb adsorption (p < 0.001), alkyl and carboxyl carbon with Cd adsorption (p < 0.001), and N-alkyl (p < 0.001) and carboxyl (p < 0.010) groups with Cu adsorption. These results are valuable to develop new biosorbents based on agricultural wastes and demonstrate the high potential of SMC to adsorb heavy metals from polluted environments.  相似文献   

20.
Pathogen removal is essential for wastewater treatment and its potential reuse in agriculture. Three field-scale wastewater treatment systems consisting of free surface flow were operated around 1.5 years receiving water from urban domestic, rural domestic and industrial sources. The study was conducted to evaluate seasonal performance of constructed wetland systems in removing Escherichia coli, Enterococci and total coliforms under continuous hydraulic flow. Results displayed that all three wetlands gain recognition in removing pathogen load with high removal efficacy till water reaches output ports. Removal efficiencies were even higher, 66–93, 78–92 and 80–94% for E. coli, Enterococci and total coliforms, respectively, within constructed wetlands. Remarkably at shorter temporal scales in CW-A, greater homogeneity of pathogen concentrations was assessed at wetland outlet sites. In outlet ports, results displayed a highly effective removal of E. coli concentration 80–90% (June 2015), 86–92% (October 2015) and 79–92% (February 2016), Enterococci 80–94% (June 2015), 83–94% (October 2015) and 80–94% (February 2016) and total coliforms 85–93% (June 2015), 87–95% (October 2015) and 88–96% (February 2016). Positive correlation was observed between bacterial indicators (E. coli–Enterococci, r = 0.038; p < 0.01 and E. coli–total coliforms, r = 0.142; p < 0.01). Removal of bacterial indicators in constructed wetland was also displayed by PCA in which three-component analysis of variance was 98.39% and showed a clear decrease in measured parameter gradients toward samples from outlet ports. Constructed wetlands provide cost-effective treatment systems for reducing the pathogen load in wastewater in variable agro-climatic conditions and thus improve water quality.  相似文献   

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