Potential of Aquatic Macrophytes as Bioindicators of Heavy Metal Pollution in Urban Stormwater Runoff

The concentrations of heavy metals in water, sediments, soil, roots, and shoots of five aquatic macrophytes species (Oenanthe sp., Juncus sp., Typha sp., Callitriche sp.1, and Callitriche sp.2) collected from a detention pond receiving stormwater runoff coming from a highway were measured to ascertain whether plants organs are characterized by differential accumulations and to evaluate the potential of the plant species as bioindicators of heavy metal pollution in urban stormwater runoff. Heavy metals considered for water and sediment analysis were Cd, Cr, Cu, Ni, Pb, Zn, and As. Heavy metals considered for plant and soil analysis were Cd, Ni, and Zn. The metal concentrations in water, sediments, plants, and corresponding soil showed that the studied site is contaminated by heavy metals, probably due to the road traffic. Results also showed that plant roots had higher metal content than aboveground tissues. The floating plants displayed higher metal accumulation than the three other rooted plants. Heavy metal concentrations measured in the organs of the rooted plants increased when metal concentrations measured in the soil increased. The highest metal bioconcentration factors (BCF) were obtained for cadmium and nickel accumulation by Typha sp. (BCF = 1.3 and 0.8, respectively) and zinc accumulation by Juncus sp. (BCF = 4.8). Our results underline the potential use of such plant species for heavy metal biomonitoring in water, sediments, and soil.     

Heavy metals in bulk precipitation and transplantedHypogymnia physodes andDicranoweisia cirrata in the vicinity of a Danish steelworks

Hypogymnia physodes (L.) Nyl. andDicranoweisia cirrata (Hedw.) Lindb. were transplanted to 12 stations in the vicinity of the steelworks in Frederiksvaerk, Denmark. The transplants were exposed for 7 mo, and samples were taken after 31, 64, 104, 154, 184, and 214 days. Bulk precipitation was collected simultaneously. The concentrations of the metals Cd, Cr, Cu, Fe, Mn, Ni, Ph, V, and Zn were analyzed by atomic absorption spectrophotometry in both transplants and bulk precipitation. The amounts of accumulated metals in the transplants were linearly correlated with fallout from the atmosphere, the bryophytes accumulating the metals slightly faster than the lichens. The metal concentrations in the transplants, as well as the bulk precipitation, followed a decreasing power curve when the distance to the steelworks was increased. It was concluded that transplanted lichens and bryophytes can be applied as monitor organisms of heavy metal pollution from the air.     

Are threatened lichen species well-protected in Spain? Effectiveness of a protected areas network

Several modelling species distribution studies have been developed, in last years, though mainly applied in higher plants, mammals or birds. However, little is known about overlooked taxa like lichens. We have evaluated the potential distribution of eleven threatened lichens in Spain and how the Natura 2000 network contributes to protect them. To overcome difficulties related to the lack of systematic surveys in those poorly known species we used only-presence data by means of ENFA (ecological-niche factor analysis). Then, we used ENFA to model the environmental niche of each species and to obtain the habitat suitability maps. In order to test the effectiveness of the Natura 2000 network, the habitat high suitability map for all species was overlapped with the network map. Our results show that all species considered present habitats requirements different from the average conditions of Spain, although clear differences exist among the species. That is, Peltigera elisabethae shows an extremely narrow niche, whereas Peltigera neckeri presents the highest ecological breadth. High temperature and long drought periods are the variables which restrict more the occurrence of these species. So, all species appear mainly confined to well-conserved forest and mountain ranges where these variables are dimmed. This mainly occurs in the oceanic northern fringe and in the higher Mediterranean mountains. In relation to the success of the Natura 2000 network, our results show that the capability of this network to protect key habitats for these species seem to be guarantied, probably because most reserves appear in mountainous areas in Spain. Evaluation of reserve network effectiveness needs the use of this type of gap analysis and especially the inclusion of ‘not charismatic’ organisms such as lichens.     

Assessment of heavy metal uptake and translocation in Dyera costulata for phytoremediation of cadmium contaminated soil

Abstract

Heavy metal pollution is a widespread global problem causing serious environmental concern. Cadmium, one of the heavy metals, is water soluble and can be transferred from soil to plants and enter into the food chain. It is detrimental to human health because it accumulates in the body and can cause renal tubular dysfunction, pulmonary emphysema and osteoporosis. This heavy metal needs to be cleaned up for a clean and safe environment. An experiment was conducted to evaluate the potential of Dyera costulata as a phytoremediator to absorb cadmium from contaminated soils. Dyera costulata seedlings were planted on six different growth media (soil + different levels of cadmium): Control, 25 ppm Cd, 50 ppm Cd, 75 ppm Cd, 100 ppm Cd and 150 ppm Cd. The highest growth performance mainly height, basal diameter and number of leaves were in the control, 50 ppm Cd and 25 ppm Cd treatments, respectively. The highest accumulation of cadmium (52.9 ppm) was in the 75 ppm Cd treatment. Among the plant parts, leaves showed the highest concentration of cadmium. Dyera costulata showed high translocation factor and low bioconcentration factor values in soil at high cadmium concentrations and was also able to tolerate and accumulate high concentrations of cadmium. The roots of Dyera costulata were found to be suitable for the absorption of cadmium in contaminated soils. This species can be an efficient phytoremediator for soils contaminated with cadmium.     

Distribution of Chromium,Nickel, and Cobalt in Different Parts of Plant Species and Soil in Mining Area of Keban,Turkey

Abstract

The distribution of chromium, nickel, and cobalt in the plant species and soil of the Zn‐Pb‐Ag sulfide deposits of the Keban area in Turkey have been studied to determine both biogeochemical indicators and biomonitoring of environmental pollution. Plants, including Euphorbia, Verbascum, and Astragalus, and their associated soil samples were collected, and the roots and shoots of these plants together with soils were analyzed by inductively coupled plasma‐mass spectrometry (ICP‐MS). The three metal concentrations in the shoots of Euphorbia samples were found to be lower than in their roots, whereas the metal concentrations in shoots of Verbascum are higher than in their roots. Although the metal concentrations in soils were found to be lower than the permissible limits for agricultural purposes, the concentrations of these metals in different parts of some plants were observed at excessive/toxic levels. As a result, the roots of Euphorbia and the shoots of Verbascum and Astragalus can be used to biomonitor environmental contamination and as biogeochemical indicators.     

Assessment of heavy metal pollution in surface sediments of the Montenegrin coast: a 10-year review

Purpose

Heavy metals are among the most common environmental pollutants, which can be introduced into coastal areas from natural and anthropogenic sources, and thereby possibly impact marine organisms and human population. Therefore, the aim of this study was to evaluate the pollution level of Montenegrin coastal sediments by determining the concentrations of 10 metals and metalloids (Fe, Mn, Zn, Cu, Ni, Pb, Cr, Cd, As, and Hg) during one whole decade.

Materials and methods

Sediment samples were collected from 11 sites along the Montenegrin coast during the 2005–2016 exposure to different levels and sources of anthropogenic impact. The extent of pollution was estimated by determining total element concentrations in the sediment. Mineralized samples were analyzed for Cu, Ni, Fe, Mn, Cr, As, Pb, Zn, Cd, and Hg. Pollution status was evaluated using the contamination factor, pollution load index, and geo-accumulation index, as well as statistical methods, such as Pearson correlation coefficient (r) and cluster analysis (CA).

Results and discussion

This study showed that concentrations of individual metals at some locations were extremely high. The metal concentrations (in mg kg^?1) ranged as follows: Fe 1995–45,498; Mn 135–1139; Zn 10–1596; Cu 3.8–2719; Ni 2.94–267; Pb 0.1–755; Cr 2.5–369; Cd 0.1–5.4; As 0.1–39.1; and Hg 0.01–14.2. The calculated concentration factor and pollution load index indicates enrichment by either natural processes or anthropogenic influences. The geo-accumulation index value (Igeo) showed that one location was strongly or extremely polluted (3.78?<?Igeo ≤?6.15) with Hg in all investigated years, while extreme Igeo values for four bioactive elements, Pb, Cd, Cu, and Zn, were found in only a few single samples.

Conclusions

On the basis of the obtained values, it can be concluded that generally higher metal contents were distributed in Boka Kotorska Bay sites, although some extreme values were also recorded at the locations outside of the Bay. Geo-accumulation index and pollution load index showed that the metal levels were high enough to pose risk to the ecosystem.

     

Effective bioremediation of heavy metal–contaminated landfill soil through bioaugmentation using consortia of fungi

Purpose

Heavy metals’ contamination of soil is a serious concern as far as public health and environmental protection are concerned. As a result of their persistent and toxic properties, heavy metals need to be removed from contaminated environments using an efficient technology. This study is aimed to determine the heavy metals’ (Ni, Pb, and Zn) bioremoval capacity of consortia of filamentous fungi from landfill leachate-contaminated soil.

Materials and methods

Three different groups of consortia of fungi, namely all isolated fungi, Ascomycota, and Basidiomycota, were employed for the bioremediation of the contaminated soil. A total of thirteen fungal species were used to make up the three consortia. The setup was kept for 100 days during which regular watering was carried out. Soil subsamples were collected at day 20, day 60, and 100 for monitoring of heavy metal concentration, fungal growth, and other physicochemical parameters.

Results and discussion

Highest tolerance index of 1.0 was recorded towards Ni and Zn concentrations. The maximum metal bioremoval efficiency was observed for soil bioaugmented with the all isolated fungi for Ni and Pb with the removal efficiencies as 52% and 44% respectively. However, 36% was realized as the maximum removal for Zn, and was for Ascomycota consortium-treated soil. The order for the heavy metal removal for Ni and Pb is all isolated fungi > Basidiomycota?>?Ascomycota, while for Zn is Basidiomycota?>?all isolated fungi > Ascomycota. Spectra analysis revealed the presence of peaks (1485–1445 cm^?1) only in the consortia-treated soil which corresponded to the bending of the C–H bond which signifies the presence of methylene group.

Conclusions

Soil treated using bioaugmentation had the best heavy metal removal as compared to that of the control. This suggests the contribution of fungal bioaugmentation in the decontamination of heavy metal–contaminated soil.

     

Analysis of Arsenic Uptake by Plant Species Selected for Growth in Northwest Ohio by Inductively Coupled Plasma–Optical Emission Spectroscopy

Abstract

Arsenic (As) contamination is widespread in the industrial areas of northwest Ohio. Plant species that both take up As and are appropriate for the climate and growth conditions of the region are needed for phytoremediation to be successfully employed. Actively growing plants from 22 species of native genera were exposed to As in hydroponics systems (either 0, 10, or 50 mg As L^?1; 1 week) and commercially available potting mix (either 0, 10, 25, 100, or 250 mg As L^?1; 2 weeks), depending on their growth conditions. Aboveground plant tissues were harvested and digested, and concentrations of As were determined by inductively coupled plasma–optical emission spectrometry. The highest tissue concentrations of As (mg As kg^?1 dw) were recorded in seven plant species: Rudbeckia hirta (661), Helenium autumnale (363 in tissues formed after exposure to As), Lupinus perennis (333), Echinacea purpurea (298), Coreopsis lanceolata (258), Lepidium virginicum (214), and Linum lewisii (214). These seven species are ecologically diverse, which suggests that phytoremediation of As using diverse assemblages of plants may be an option for a variety of environments.     

Bioaccumulation of heavy metals by Cyperus malaccensis and Spartina alterniflora in a typical subtropical estuary (Min River) of Southeast China

Purpose

To understand the bioaccumulation of heavy metals by Cyperus malaccensis (CM) and Spartina alterniflora (SA) in a typical subtropical estuary (Min River) of Southeast China, the concentrations of five metals (Pb, Cr, Cu, Zn, and Ni) in plants and sediments of CM and SA marshes were determined.

Materials and methods

Two experimental plots (no flooding plot and flooding plot) were established in the intertidal zone of the Min River estuary in July 2015, and, in each plot, in situ sampling was conducted in CM and SA marshes, respectively. The concentrations of heavy metals in all samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) analysis.

Results and discussion

Vertical variations of the five metals differed between marshes or plots, and, in most cases, there was no evidence of grain-size composition (particularly for clay) and sediment organic matter (SOM) contributing to the sorption of significant amounts of metals in sediments of different marshes. Flooding regime was an important factor inducing the difference of metals in sediments of the two experimental plots. Heavy metal levels in different tissues of CM and SA differed within species or plots. For the five metals, the root was generally the main stock, and, as water condition changed from non-flooding to flooding, allocations of Pb, Cu, and Zn in CM and SA decreased while those of Cr increased. The accumulation factors [AF_s] of heavy metals in different tissues of CM and SA also differed between species or plots. In most cases, the [AF]_plant of different metals were less than 1, implying that the metal accumulations in CM and SA of the two plots were uncommon.

Conclusions

This study found that Cu and Zn pollution in non-flooding conditions and Pb and Cu pollution in flooding conditions might be more serious, indicating that intertidal sediments might be severely contaminated by the three metals if effective measures are not taken to control the pollutant loadings of the Min River estuary in the future. Moreover, CM generally accumulated more Pb, Cu, and Zn while SA absorbed more Cr and Ni (particularly in flooding conditions), implying that, when determining environmental pressures, the two plants could be used as specified biological indicators.

     

Oribatid communities (Acari: Oribatida) inhabiting saxicolous mosses and lichens in the Krkonoše Mts. (Czech Republic)

Composition, structure and diversity of oribatid communities inhabiting saxicolous mosses and lichens were studied in the Krkonoše Mts. (Czech Republic) along an altitudinal gradient reaching from submontane to alpine belt. Samples of various saxicolous mosses and lichens from 197 stands were collected. Impact of altitude and dominant moss or lichen species on community structure were analysed. Data were evaluated using divisive cluster analysis and direct ordination analysis. Altogether 104 oribatid species were recorded. Four groups of saxicolous habitats, which differ in the composition of their oribatid communities, were distinguished:1. Mosses below the upper forest line with accessory higher plants growing on their surface. Higher plants indicate favourable moisture conditions and an appreciable degree of humus layer development. Their oribatid mite community is rich in number of frequent species and consists of ubiquitous species, ubiquitous species with higher requirements for moisture and amount of decaying organic matter, a high number of soil dwelling species and several hygrophilous species.2. Mosses below the upper forest line without accessory higher plants. They predominantly include mosses with no or only a weakly developed humus layer. Their oribatid mite community is composed mainly of ubiquitous species and a few soil dwelling species.3. Mosses in open areas above the upper forest line. Their humus layer is not developed at all or only weakly. Humidity and temperature fluctuations are here much higher compared with mosses below the upper forest line, which are protected by the specific forest microclimate. Their oribatid mite community is poor in number of frequent and dominant species and consists predominantly of Oribatula cf. pallida and two specialised species living exclusively in mosses and lichens (Mycobates tridactylus and Trichoribates monticola).4. Saxicolous lichens. Their oribatid community comprises ubiquitous species, species frequent both in mosses and lichens and several species with a strong affinity to lichens (Mycobates carli and five species of the genus Carabodes).     

Distribution of airborne heavy metals as measured in the lichens Ramalina stenospora and Parmotrema praesorediosum in Baton Rouge,Louisiana

The lichens Ramalina stenospora and Parmotrema praesorediosum were collected from 30 stations in the greater metropolitan area of Baton Rouge, Louisiana and analyzed for Al, Cu, Fe, Zn, and Pb content. A univariate analysis of the data showed a significant difference between metal concentrations and sampling stations. When the stations were separated into two groups representing those in the industrial and urban zones, a discriminant analysis was over 90% successful in correctly assigning stations based solely on metal concentrations. No significant differences in metal concentration with species could be observed. Average metal concentrations for the two lichen species were used to construct contours and three-dimensional plots of metal distribution across the study area which clearly demonstrate the effects of the industrial zone on airborne metal levels.     

Airborne heavy metal pollution in the environment of a danish steel plant

A survey of heavy metal deposition was carried out in the vicinity of a Danish steel plant. Bulk precipitation and transplanted lichen (Hypogymnia physodes (L.) Nyl.) were sampled at 12 stations in the environment before and after the production had been converted from open-hearth furnaces to electric-arc furnaces. The samples were analyzed for Cd, Cr, Cu, Fe, Mn, Pb and Zn. The results show that heavy metal pollution from the steelworks still is severe and that it follows a decreasing power curve when the distance to the steelworks is increased. However, a reduction in the deposition of heavy metals close to the steelworks has been observed, pointing to the conclusion that the change from a situation of emission through a 46 m stack without any filter to emission from the electric arc furnaces equipped with bag-filters has lead to changes in the emission. At the sampling stations with the highest deposition levels measured in bulk precipitation the corresponding concentrations in the lichens were relatively lower indicating a change in particle size distribution. Within each station there was a direct proportionality of metal concentrations in lichens and atmospheric fallout measured in bulk precipitation.     

Accumulation of cadmium in growing peanut (Arachis hypogaea L.) seedlings—Its effect on lipid peroxidation and on the antioxidative enzymes catalase and guaiacol peroxidase

In plants exposed to high metal concentrations, mechanisms to counteract the oxidative burst are crucial for its survival. To investigate the temporal sequence of physiological reactions of peanut seedlings (Arachis hypogaea L.) to cadmium exposure, seeds were cultured in increasing concentrations of CdCl₂, ranging from 50 to 300 μM. Germination frequency was scored, and the distributions of Cd in root, stem, and leaves were determined after 2 and 4 weeks of culture. Lipid peroxidation and activities of antioxidative enzymes including catalase (CAT; EC 1.11.1.6) and guaiacol peroxidase (GPX; EC 1.11.1.7) were estimated in these three parts of the plant. Germination of seedlings was not affected, but the growth of seedlings was severely suppressed with increasing concentrations of CdCl₂ and incubation period. Pattern of Cd distribution in the three organs varied with concentration and period of exposure to Cd. Increased lipid peroxidation was detected in all parts of the developing seedlings with increasing metal accumulation. Catalase and guaiacol peroxidase activity varied in the three parts of the seedlings with concentration of Cd and incubation period. Guaiacol peroxidase activity appears to be more active in scavenging the reactive oxygen species in developing peanut seedlings. The results of the present experiment demonstrate the advantages of a tissue‐culture model system in studying the complex network of interactions of various factors in stress tolerance.     

Heavy metals in the lichen Ramalina duriaei transplanted at biomonitoring stations in the region of a coal-fired power plant in Israel after 3 years of operation

A survey of the heavy metal content in a transplanted lichen Ramalina duriaei (De Not.) Bagl. was carried out in the region of an Israeli coal-fired power plant. Nickel, Cr, Cu, and Zn were analyzed in the lichen exposed to environmental influences for a period of 1 yr. The concentrations of metals were compared with the concentrations of the same metals measured in R. duriaei transplanted to the study area prior to the operation of the power plant. The results show that after the 1983–1984 period, the regional concentrations of Cr in the transplanted lichen thalli were found to be higher than in the lichen thalli transplanted to the same sites during the period February 1979-March 1980, prior to the operation of the coal-fired power plant. A regional decrease in Zn concentration in the lichen exposed during the latter period is probably linked to the decrease in the use of this metal as a constituent of foliar nutrients in agriculture. The regional increase of Cr in the 1983–1984 lichen material is probably connected with the operation of the Maor David coal-fired power plant located at Sharonim. A local increase in the Ni and Cr concentrations was found in the lichen transplanted to a nature reserve located north of the power station.     

Biomonitoring of Trace Elements in Air and Soil Compartments Along the Major Motorway in France

The impact on the environment of Cd, Pb and Zn emissions from the A1 motorway, one of the busiest in France, was based on a simultaneous analysis of lichens, fungi and soil.The study was conducted in 12 rest areas located along a 55 kmstretch of the motorway. Cd, Pb and Zn concentrations in the top soil horizon (0–10 cm) largely exceeded their concentrations at the control site.The Cd-, Pb- and Zn levels in fruiting bodies of fungi Armillaria mellea, Coprinus comatus, Marasmius oreades and Paxillus involutus were highly variable between sites. The contamination degree of transplanted thalliof Parmelia caperata was well correlated to the cumulated traffic on the western side. On the eastern side, heavy metals originated from the traffic but also from neighbouring sources (urbanization and agricultural practices). Although lead levels are decreasing, leaded petrol is still on offer and lead remains an indicator of vehicle pollution.     

Air Pollution and Lichen Physiology. Physiological Responses of Different Lichens in a Transplant Experiment Following an SO2-Gradient

Four lichen species, Parmelia sulcata Taylor, Hypogymnia physodes (L.) Nyl., Cetraria islandica (L.)Ach., and Bryoria fuscescens (Gyelnik) Brodo andHawksworth were exposed during autumn and winter at differentsites of the Erzgebirge (Ore Mountains), the Fichtelgebirge andcontrol sites. All lichens tested became visibly damaged withtime. Thallus bleaching started from the edges and went on tothe centre of the thallus. Sites of facilitated gas exchangelike the soralia of P. sulcata and the pseudocyphelles ofC. islandica became preferentially bleached. The sulfateconcentration increased with exposure time reaching 200% ofunpolluted controls. In contrast to coniferous trees (e.g. Picea abies), further exposure lead to a reduction in the S-concentration in the lichens, as sulfate and otherintracellular metabolites were leached from the thalli due tomembrane damage. The changes in the K-concentration proved tobe an excellent measure for membrane leakiness; it wascorrelated with time of exposure and with SO₂ concentrations at the different sites. Photosynthetic capacityand respiration were also strongly affected. Depending on theSO₂-dose, the Bryoria species were unable tophotosynthesize as early as 4–8 weeks after exposure, whereasCetraria and Hypogymnia showed clear reduction intheir ability to photoreduce CO₂ within 8–10 weeks ofexposure in the field. Parmelia sulcata was found to bethe most tolerant species. After 3–4 months, photosynthesis wasreduced by only 30%. The bioindicative value of theseobservations is discussed.     

Distribution,risk assessment,and source analysis of heavy metals in sediment of rivers located in the hilly area of southern China

Purpose

River sediment, the important sink and source of heavy metals, can provide critical information for aquatic ecosystem health. Heavy metal pollution has been a serious problem facing river systems worldwide and can adversely affect human beings via the food chain. However, no comprehensive study has been conducted on heavy metal pollution in sediments of river systems in the hilly area of southern China, which plays a key role in water supply and ecosystem balance. This study is aimed at comprehensively studying the pollution status of heavy metals in river sediments in the hilly area of southern China and apportioning sources.

Materials and methods

A total of 39 superficial sediment samples were collected from the upstream, midstream, and downstream of 13 rivers (Xiangjiang River, Zishui River, Yuanjiang River, and Lishui River located in Hunan Province; Ganjiang River, Xinjiang River, Fuhe River, Raohe River), and Xiushui River located in Jiangxi Province; Qiantangjiang River and Oujiang River located in Zhejiang Province; Minjiang River and Jiulongjiang River located in Fujian Province) in the hilly area of southern China. The total concentrations of metals of Mn, Zn, Cr, Co, Ni, Cu, As, Cd, Sb, Pb, and V were analyzed using the inductively coupled plasma-mass spectrometry method. The pollution status and potential ecological risk were assessed with the geoaccumulation index (I_geo), sediment quality guidelines (SQGs), and potential ecological risk index (RI). The source apportionment of heavy metals was performed by correlation analysis and principle component analysis (PCA).

Results and discussion

Results indicated that Mn, Zn, and Pb concentrations were significantly higher than other metals, especially in the upstream of the Jiulong River and midstream and downstream of the Xiangjiang River. Pollution assessment indicated that Cd pollution of sediments was most serious and that more than 50% of sampling sites were significantly polluted, with a very high potential ecological risk. The rivers in Hunan provinces (HN) were identified as the priority controlled rivers because of the high I_geo and RI index values. Correlation and PCA analysis indicated that Mn, Pb, and Zn originated from natural and mineral exploitation activities; As, V, Ni, and Sb originated from industrial wastewater and mineral-smelting activities; Cu and Co originated from agricultural activities; Cr and Ni originated from natural sources. While the most polluted Cd came from a combination of multiple sources described above.

Conclusions

Results indicated that Cd was the most common heavy metal pollutant, especially in river sediments of Hunan Province. Anthropogenic activities have become the main source of heavy metals in the river sediments of the hilly area of southern China. Special attention should be paid to Cd, and measures must be taken to prevent from further anthropogenic influence on heavy metal pollution.

     

Heavy metals in the soil–plant system of the Don River estuarine region and the Taganrog Bay coast

Purpose

The aim of this work was to study the level and degree of mobility of heavy metals in the soil–plant system and to perform bioindication observations in the Don River estuarine region and the Russian sector of the Taganrog Bay coast.

Materials and methods

The objects of the study included samples of zonal soils (chernozem) and intrazonal soils (alluvial meadow and alluvial-stratified soils, Solonchak, sandy primitive soil) from monitoring stations of the Don river estuarine region and the Taganrog Bay coast, as well as their higher plants: Phragmites australis Cav., Typha angustifolia L., Carex riparia Curtis, Cichorium intybus L., Bolboschoenus maritimus L. Palla, and Rumex confertus Willd. The total concentrations of Mn, Ni, Cd, Cu, Zn, Pb, and Cr in the soils were determined by X-ray fluorescent scanning spectrometer. The concentration of heavy metal mobile forms exchangeable, complex compounds, and acid-soluble metal were extracted using the following reagents: 1 N NH₄Ac, pH 4.8; 1 % EDTA in NH₄Ac, pH 4.8; 1 N HCl, respectively. Heavy metals in plants were prepared for analysis by dry combustion at 450 °C. The heavy metal concentration in extracts from plants and soils was determined by AAS.

Results and discussion

The total contents of heavy metals in the soil may be described with a successively decreasing series: Mn?>?Cr?>?Zn?>?Ni?>?Cu?>?Pb?>?As?>?Cd. The total concentrations of As, Cd, and Zn in the soil exceed the maximum permissible concentrations levels. Contamination of alluvial soils in the estuarine zone with mobile Сu, Zn, Pb, and Cd has been revealed, which is confirmed by the high bioavailability of Cu and Zn and, to a lesser degree, Cd and Pb accumulating in the tissues of macrophytic plants. Data on the translocation of elements to plant organs have showed their predominant accumulation in the roots. Bioindication by the morphofunctional parameters of macrophytic plants (with a Typha L. species as an example) can be used for revealing the existence of impact zones with elevated contents of metals in aquatic ecosystems.

Conclusions

The results revealed that increased content of Zn, Pb, Cu, Ni, and As in soil have anthropogenic sources. The high content of Cr in the soils is related to the lithogenic factor and, hence, has a natural source.

     

Heavy‐metal toxicity in plants 1. A crisis in embryo

Abstract

Heavy metals are often added indiscriminantly to soils in pesticides, fertilizers, manures, sewage sludges, and mine wastes, causing an imbalance in nutrient elements in soils. Heavy‐metal toxicity causes plant stress in various degrees dependent on the tolerance of the plant to a specific heavy metal. The objectives of this study were (i) to show that plant species and soils respond differently to heavy metals and (ii) to show the necessity for proper quantity and balance of heavy metals in soils for plant growth.

Three Fe‐inefficient and three Fe‐efficient selections of soybean, corn, and tomato were grown on two alkaline soils with Cu and Zn ranging from 14 to 340 and Mn from 20 to 480 kg/ha. Heavy‐metal toxicity caused Fe deficiency to develop in these plants. The Fe‐inefficient T3238fer tomato and ys₁/ys₁ corn developed Fe deficiency on all treatments and both soils. T3238FER tomato (Fe‐efficient) did not develop heavy metal toxicity symptoms on any treatment or soil. The soybean varieties and WF9 corn were intermediate in their response.

The unpredictable response of both the soil and the plant to heavy metals make general recommendations difficult. In order to maintain highly productive soils, we need to know what we are adding to soils and the consequences. Without some control, the continued addition of heavy metals to soils is a crisis in embryo.     

Use of flue gas desulfurization (FGD) by‐product gypsum on alfalfa

Abstract

Subsoil acidity in northeast United States has been associated with decreased yield and decreased water and fertilizer nitrogen (N) utilization by forages. Surface applications of gypsiferious products has been shown to reduce subsoil acidity largely caused by high levels of soluble aluminum (Al). Our objective was to test the effectiveness and safety of using FGD gypsum to increase dry matter (DM) yields of alfalfa (Medicago sativa L.). Four and one‐half, 9, and 18 mt/ha of either commercially available agricultural gypsum or two gypsum by‐products were applied to a Rayne soil (Fine‐loamy, mixed, mesic Typic Hapludult) with a strongly acid subsoil. Agricultural and FGD gypsum increased alfalfa DM yields by as much as 21 and 14%, respectively. Correspondingly, in the subsoil, soluble Al decreased and calcium (Ca) content and Ca:Al ratio increased. Heavy metal concentrations in either the alfalfa or soils were not increased by any treatment. However, S in the alfalfa grown at the highest treatments approached concentrations that are considered to be toxic to grazing animals.