Copper and lead concentrations in salt marsh plants on the Suir Estuary,Ireland

Concentrations of Cu and Pb were determined in the roots and shoots of six salt marsh plant species, and in sediment taken from between the roots of the plants, sampled from the lower salt marsh zone at four sites along the Suir Estuary in autumn 1997. Cu was mainly accumulated in the roots of monocotyledonous and dicotyledonous species. Pb was mainly accumulated in the roots of monocotyledons, while dicotyledons tended to accumulate Pb in the shoots. In the case of Aster tripolium there was a clear differentiation in the partitioning of Pb within the plant, between low and high salinity sites. At the low salinity sites, Pb accumulated only in the roots while at the high salinity sites there was a marked translocation to the shoots. The increase in Pb concentrations in roots and shoots of A. tripolium was accompanied by a concomitant decrease in sediment concentrations of Pb. This inverse correlation between sediment and plant concentrations of Pb was also recorded for Spartina spp. and Schoenoplectus tabernaemontani but in the case of these species the roots contained higher concentrations of Pb regardless of salinity levels. These differences in accumulation of Cu and Pb in various salt marsh species, and the influence of salinity on the translocation of Pb in A. tripolium in particular, should be taken into account when using these plants for biomonitoring purposes.     

Fate and effects of heavy metals in salt marsh sediments

The fate and effects of selected heavy metals were examined in sediment from a restored salt marsh. Sediment cores densely covered with Spartina patens were collected and kept either un-amended or artificially amended with nickel (Ni) under standardized greenhouse conditions. Ni-amendment had no significant effect on the fate of other metals in sediments, however, it increased root uptake of the metals. Metal translocation into the shoots was small for all metals. Higher Ni concentrations in plants from amended cores were accompanied by seasonal reductions in plant biomass, photosynthetic capacity and transfer efficiency of open photosystem II reaction centers; these effects, however, were no longer significant at the end of the growing season. Root colonization by arbuscular mycorrhizal fungi (AMF) resembled that of natural salt marshes with up to 20% root length colonized. Although Ni-amendment increased AMF colonization, especially during vegetative growth, in general AMF were largely unaffected.     

A survey of zinc, copper and cadmium concentrations in salt marsh plants along the Dutch coast

In autumn 1986, plants and soil were collected from the lower and the higher salt marsh zones of salt marshes along the Dutch coast. The main purpose was to get an overview of Zn, Cu and Cd concentrations in six dominant species of salt marsh plants. The roots and shoots of the plants were analysed for Zn, Cu and Cd. The highest heavy metal concentrations were found in plants collected from salt marshes near harbour areas and/or that are known to receive contaminated fluvial sediment. Dicotyledonous plant species tended to have similar heavy metal concentrations in roots and shoots, whereas in monocotyledonous species the concentrations in the roots were two to three times higher than in the shoots. Differences in accumulation in the roots between elements and between plant species were found. Cd was accumulated more than Zn or Cu. Triglochin maritima shows a low Cd uptake by roots, whereas Spartina anglica and Scirpus maritimus tend to accumulate it. The fraction of soil particles smaller than 63 microm, loss on ignition and Zn, Cu and Cd concentrations were determined in soil samples. The highest Zn, Cu and Cd concentrations in the soil were found at salt marshes in the Western Scheldt area and were nine, five and 20 times higher than background levels, respectively.     

Ability of salt marsh plants for TBT remediation in sediments

Introduction  

The capability of Halimione portulacoides, Spartina maritima, and Sarcocornia fruticosa (halophytes very commonly found in salt marshes from Mediterranean areas) for enhancing remediation of tributyltin (TBT) from estuarine sediments was investigated, using different experimental conditions.     

Accumulation and biological cycling of heavy metal in four salt marsh species, from Tagus estuary (Portugal)

Pools of Zn, Cu, Cd and Co in leaf, stem and root tissues of Sarcocornia fruticosa, Sarcocornia perennis, Halimione portulacoides and Spartina maritima were analyzed on a bimonthly basis, in a Tagus estuary salt marsh. All the major concentrations were found in the root tissues, being the concentrations in the aboveground organs neglectable for sediment budget proposes, as seen by the low root-aboveground translocation. Metal annual accumulation, root turnovers and cycling coefficients were also assessed. S. maritima showed the higher root turnovers and cycling coefficients for most of the analyzed metals, making this a phytostabilizer specie. By contrast the low root turnover, cycling coefficient and low root necromass generation makes S. perennis the most suitable specie for phytoremediation processes. Although the high amounts of metal return to the sediments, due to root senescence, salt marshes can still be considered sinks of heavy metals, cycling heavy metals mostly between sediment and root.     

Halophyte vegetation influences in salt marsh retention capacity for heavy metals

We analysed concentrations of Cu, Cd and Pb in above and belowground tissues of the halophyte species Halimione portulacoides and Spartina maritima, as well as in sediments and pore water between the roots in a Tagus estuary salt marsh (Portugal). From these results we calculated the pools of metals in the compartments mentioned above. Relative percentages of accumulation in each pool were also determined. Our aim was to determine how the type of vegetation in the salt marsh affects overall metal retention capacity of the system. It was concluded that areas colonised by H. portulacoides are potential sources of Cu, Cd and Pb to the marsh ecosystem, whereas areas colonised by S. maritima are more effective sinks at least for Cu and Cd. Consequently, S. maritima seems to contribute more effectively to the stabilisation of metals in salt marsh sediments, reducing their availability to the estuarine system.     

Fate and effects of nutrients and heavy metals in experimental salt marsh ecosystems

Fate and effects of the macro nutrients nitrogen and phosphorus, and the heavy metals zinc, copper and cadmium, brought into experimental salt marsh ecosystems via sediment supply, were studied over a three-year period. The supply of sediment from the Marsdiep (at a low and high rate) and from the harbour of Delfzijl (at a high rate) led to an increase of the macro nutrients and heavy metals in the top soil. The growth of the salt marsh plants Aster tripolium, Puccinellia maritima and Spartina anglica and the uptake of the macro nutrients and heavy metals by the plants was only slightly affected by the addition of sediment. A high load of sediment led to an increase in growth or in the concentrations of the macro nutrients or heavy metals in the plants at a number of sampling dates, but only minor differences between treatments were found. From a mass balance constructed over a three-year study period it could be concluded that about 50% of the macro nutrients and heavy metals were retained in the salt marsh sediment. This was equal to the retained amount of organic matter, indicating that retention of the elements was closely related to retention of organic matter. The 50% loss of the macro nutrients and heavy metals probably occurred via ebb tides after resuspension of sediment and organic matter.     

Suitability of different salt marsh plants for petroleum hydrocarbons remediation

The suitability of the salt-marsh species Halimione portulacoides, Scirpus maritimus, Juncus maritimus and an association of the last two for remediation of petroleum hydrocarbons (PHC) in soil was investigated. An outdoor laboratory experiment (microcosm-scale) was carried out using contaminated soil collected in a refinery, as a complement of another study carried out in the refinery environment (mesocosm-scale). Soil samples with old contamination (mainly crude oil) and with a mixture of the old and recent (turbine oil) contamination were tested. Studies in both micro- and mesocosm-scale provided results coherent in substance. The presence of S. maritimus caused removal of old contamination which was refractory to natural attenuation (after 7 months of exposure, efficiency was 13% when only old contamination was present and 40% when the soil also contained recent contamination). H. portulacoides (only included in the microcosm-scale study) revealed also potentiality for PHC remediation, although with less efficiency than S. maritimus. Degradation of recent contamination was also faster in the presence of plants (after 7 months: 100% in the presence of S. maritimus vs. 63% in its absence). As these species are common in salt marsh areas in Atlantic coast of Europe, it is probable they will be also useful for recovering coast sediments. In contrast, J. maritimus and association did not reveal capability to remove PHC from soil, the presence of J. maritimus inhibiting the capability of S. maritimus.     

Spatial and seasonal variation in heavy metals in interstitial water of salt marsh soils

The composition of interstitial water collected from a salt marsh in NW Spain showed clear seasonal and spatial variations associated with redox cycles of Fe and S. In the summer, salinity increased in all soils as a consequence of the increase in evapotranspiration. The pH and concentrations of heavy metals also differed with season, but not all environments showed the same variations. Soils not colonized by plants had the highest pH and lowest heavy metal concentrations in the summer. These results support the idea that higher temperatures lead to an increase in the activity of sulfate-reducing bacteria, which in turn leads to an increase in alkalinity and concentration of sulfides in the water. Trace metals tend to precipitate with sulfides under these conditions and are removed from the interstitial water. In contrast, in the soils colonized by Spartina maritima, the oxidation of metal sulfides during the summer led to a decrease in pH and an increase in the metal concentrations in the interstitial water. The results obtained concur with those found for seasonal variations in metal sulfides in soils from the same salt marsh.     

Microbial processes in the rhizosphere soil of a heavy metals-contaminated Mediterranean salt marsh: a facilitating role of AM fungi

We investigated the relationship of the zonal pattern followed by the vegetation in a polluted Mediterranean salt marsh, in semiarid south-eastern Spain, with the microbiological and biochemical properties (labile C fractions, oxidoreductases and hydrolases) of the rhizosphere soil of two halophyte species, Arthrocnemum macrostachyum and Sarcocornia fruticosa, and with the degree of arbuscular mycorrhizal (AM) colonisation in their rhizospheres. Levels of plant biomass and cover were inversely related to heavy metal contents and salinity. The concentrations of Fe, Cu, Mn and Pb extracted with DTPA hardly varied among the different zones of the salt marsh. The dehydrogenase and phosphatase activities, the soluble C and water-soluble carbohydrates concentrations and the extent of root colonisation were greater in the salt marsh zones of lower soil salinity and lower metal concentration. Urease and beta-glucosidase activities were not detected in the salt marsh. Plant biomass and cover showed positive relationships with mycorrhizal colonisation (R=0.773, P<0.001; R=0.874, P<0.001, respectively). Mycorrhizal colonisation was negatively correlated with the contents of Pb and Zn in plant tissues. This work supports the view that reduced plant uptake of toxic metals, particularly lead, could be involved in the beneficial effects of AM fungi on plant development in Mediterranean salt marshes contaminated with mining wastes.     

Monitoring heavy metal pollution by aquatic plants

Introduction

The copper bioaccumulation by the floating Lemna minor and by the completely submerged Ranunculus tricophyllus as a function of exposure time and copper concentration was studied, with the aim of proposing these species as environmental biosensors of the water pollution.

Results

The results show that both these aquatic angiosperms are good indicators of copper pollution because the copper uptake is the only function of metal concentration (water pollution).

Conclusion

Uptake behavior is reported as a function of the time and concentration, based on the results of a 3-year study. Kinetic evaluations are proposed.     

Monitoring heavy metal concentrations in leachates from a forest soil subjected to repeated applications of sewage sludge

The aim of the study was to establish whether the repeated application of sewage sludge to an acid forest soil (Dystric Cambisol) would lead to short-term groundwater contamination. Sludge was applied at four loading rates (0, 2.4, 17 and 60 Mg ha⁻¹) in two consecutive years and leachates were analysed. Heavy metal inputs to soils at the lowest dose were below EC regulations but, at higher doses, limits for Zn, Cd, Cr and Ni were exceeded. Repeated application of sludge at 60 Mg ha⁻¹ resulted in significantly (P < 0.05) higher concentrations of Zn, Cd, Cr and Ni in the leachates than with other treatments. The drinking water standards for Cd and Ni were surpassed in all treatments. Control plots were contaminated by groundwater flow despite the existence of buffer zones between plots. This complicated interpretation of the results, highlighting the importance of careful design of this type of experiment.     

Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil

Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer + rapeseed residue (N70 + R), 30% mineral N fertilizer + rapeseed residue (N30 + R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70 + R and N30 + R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability.     

Heavy metal concentrations in soil and earthworms in a floodplain grassland

We determined accumulated heavy metal concentrations (Cd, Pb, Cu, Zn) of earthworms in moderately contaminated floodplain soils. Both soil and mature earthworms were sampled before and after flooding and earthworm species were identified to understand species specific differences in bioconcentration. Accumulated metal concentrations in floodplain earthworms differed before and after flooding. Differences in uptake and elimination mechanisms, in food choice and living habitat of the different earthworm species and changes in speciation of the heavy metals are possible causes for this observation. Regression equations taken from literature, that relate metal accumulation by earthworms in floodplains as a function of metal concentration in soil, performed well when all species specific data were combined in an average accumulation, but did not address differences in accumulation between earthworm species.     

生物酶生态修复重金属污染土壤

以多种重金属污染的土壤为材料,研究了酶对重金属的去除效果.在单因素实验基础上,采用响应面法对重金属去除的反应条件进行优化,结果表明,α-淀粉酶质量浓度0.2%、pH 3.5、反应时间12 h为最佳淋洗修复条件,Cd、Cr、Cu、Ni、Zn去除率分别为82.36%、75.02%、38.38%、34.69%和57.54%,去除率的大小顺序为Cd >Cr >Zn >Cu >Ni.酶作为土壤的组成部分,利用酶修复重金属污染的土壤,可以降低环境风险,具有较好应用前景.     

The influence of pH and organic matter content in paddy soil on heavy metal availability and their uptake by rice plants

The experiments were done to investigate the effect of soil pH and organic matter content on EDTA-extractable heavy metal contents in soils and heavy metal concentrations in rice straw and grains. EDTA-extractable Cr contents in soils and concentrations in rice tissues were negatively correlated with soil pH, but positively correlated with organic matter content. The combination of soil pH and organic matter content would produce the more precise regression models for estimation of EDTA-Cu, Pb and Zn contents in soils, demonstrating the distinct effect of the two factors on the availability of these heavy metals in soils. Soil pH greatly affected heavy metal concentrations in rice plants. Furthermore, inclusion of other soil properties in the stepwise regression analysis improved the regression models for predicting straw Fe and grain Zn concentrations, indicating that other soil properties should be taken into consideration for precise predicting of heavy metal concentrations in rice plants.     

Soil and street dust heavy metal concentrations in and around Cuenca, Ecuador

Lead, cadmium and zinc concentrations have been obtained in a total of 83 soil and dust samples in and around the city of Cuenca, Ecuador. Elevated heavy metal concentrations were observed in the city, with comparable Pb concentrations to those commonly found in European and North American cities. Lead concentrations were also elevated above the estimated regional background (less than 9 microg g(-1)) along a rural track used by about 100 vehicles per day. The extent of the contamination by Cd and Zn was restricted to the urban area.     

Recent advances in physiological and molecular mechanisms of heavy metal accumulation in plants

Environmental Science and Pollution Research - Among abiotic stress, the toxicity of metals impacts negatively on plants’ growth and productivity. This toxicity promotes various perturbations...     

Occurrence of heavy metal in water,soil, and plants in fields irrigated with industrial wastewater in Sabata town,Ethiopia

Environmental Science and Pollution Research - Industrial wastes have been increasingly discharged into water and soil, and causing environmental pollution in Ethiopia. This study examined the...     

Interspecific variation in heavy metal body concentrations in Hong Kong marine invertebrates

Accumulated body concentrations of cadmium, copper and zinc were investigated in 19 species of intertidal invertebrates (the barnacles Tetraclita squamosa, Capitulum mitella, Balanus amphitrite, Megabalanus volcano, the bivalves Saccostrea cucullata, Septifer virgatus and Brachidontes atratus, the chiton Acanthopleura japonica and the gastropods Cellana grata, Cellana toreuma, Patelloida saccharina, Patelloida pygmaea, Siphonaria japonica, Tegula argyrostoma, Lunella coronata, Monodonta labio, Nerita albicilla, Thais clavigera and Thais luteostoma) collected from a relatively unpolluted area in Hong Kong, i.e. two shores within the Cape d'Aguilar Marine Reserve. In general body metal concentrations could be explained by the accumulation strategy of the analysed organism and by physiological requirements for the essential metals, i.e. copper and zinc. Zinc concentrations were, therefore, greatest in the barnacles and the oyster S. cucullata. Copper concentrations were greatest in those gastropods containing the respiratory pigment haemocyanin and in S. cucullata. One species collected from the sheltered shore, i.e. T. luteostoma, had much higher copper body concentrations compared with exposed shore conspecifics and this may be attributed to a diet that was dominated by oysters, which have high copper body concentrations. In contrast to both copper and zinc, cadmium body concentrations showed little interspecific variation.