Evaluation of ecotoxicological and chemical properties of soil amended with Hudson River (New York, USA) sediment

Remediation of soils on municipal rendering plant territories using Miscanthus × giganteus

Phytoremediation, as a cost-effective, highly efficient, environmentally friendly, and green approach, gained attention to the removal of metals, including heavy metals, from contaminated soils. The toxic nature of heavy metals can have an adverse effect on human health and the ecosystem, and their removal remains a worldwide problem. Therefore, in this study, a field experiment was carried out to evaluate the potential of Miscanthus × giganteus for the removal of ten microelements and heavy metals (Al, Zn, Fe, Pb, Cd, Co, Cr, Cu, Mn, Ni) from contaminated soil in the territory of a Municipal Waste Rendering Plant. Moreover, the effect of the incorporation of soil improver obtained upon composting biodegradable waste as well as the addition of highly contaminated post-industrial soil on the efficiency of phytoremediation and plant growth was described. The soil improver (SK-8) was applied to the soil at a rate of 200 Mg ha^-1 and 400 Mg‧ha^-1. Meanwhile, in the last object, 100 Mg‧ha^-1 of highly contaminated post-industrial soil was added. Herein, the research was aimed at assessing the possibility of phytoextraction of heavy metals from soils with different physicochemical properties. The results showed that plants cultivated in soil with 400 Mg‧ha^-1 of soil improver exhibited the highest yield (approximately 85% mass increase compared to the soil without additives). Furthermore, the application of a single dose of SK-8 (200 Mg ha^-1) increased the uptake of Al, Fe, Co, Pb, Mn, Ni, and Cd by Miscanthus × giganteus compared to the soil without additives. Additionally, the performed biotests demonstrated no or low toxicity of the investigated soils affecting the test organisms. However, in all experiments, the phytorecovery of the elements did not exceed 1% of the amount introduced to the soil, which may result from a short cultivation period and large doses of SK-8 or highly contaminated post-industrial soil.

Ecological and Health Risk Assessments of Heavy Metals Contained in Sediments of Polish Dam Reservoirs

This study aimed at investigating the distribution of heavy metals (HMs: Zn, Pb, Cd, Ni, Cr, and Cu) in the bottom sediments of 28 reservoirs covered area of Poland. The paper evaluates the pollution of sediments with HMs and their potential toxic effects on aquatic organisms and human health on the basis of results provided by the Chief Inspectorate of Environmental Protection in Poland. The average concentrations of HMs in the bottom sediments of the reservoirs were as follows: Cd < Ni < Cr < Cu < Pb < Zn. (0.187, 7.30, 7.74, 10.62, 12.47, and 52.67 mg∙dm−3). The pollution load index values were from 0.05 to 2.45. They indicate contamination of the bottom sediments in seven reservoirs. The contamination-factor values suggest pollution with individual HMs in 19 reservoirs, primarily Cr, Ni, Cu, and Pb. The analysis showed that only two reservoirs had the potential for toxic effects on aquatic organisms due to high concentrations of Cd and Pb. The hazard index values for all the analyzed HMs were less than one. Therefore, there was no non-carcinogenic risk for dredging workers. The reservoirs were divided into two groups in terms of composition and concentration values. Reservoirs with higher concentrations of HMs in bottom sediments are dispersed, suggesting local pollution sources. For the second group of reservoirs, HMs’ concentrations may be determined by regional pollution sources. The analysis showed that Pb, Zn, and Cd concentrations are higher in older reservoirs and those with higher proportions of artificial areas in their catchments. Concentrations of Ni, Cu, and Cr are higher in reservoirs in south Poland and those with higher Schindler’s ratios.

Immobilisation of metals from bottom sediments using two additives and thermal treatment

A major problem associated with the land-based management of bottom sediments is their contamination with metals. The aims of the study were: 1) to use two additives for the immobilisation of metals; and 2) to evaluate the effect of three combustion temperatures on metal content and bottom sediment properties. The mixtures were prepared using contaminated bottom sediment and the following waste materials: cellulosic waste and biomass ash. In the second experiment, the bottom sediment samples were subjected to a thermal process, and three temperatures were chosen 500/800/950 °C. Overall, the addition of cellulosic waste and biomass ash to acidic, metal-contaminated bottom sediments significantly improved the properties of the resulting mixtures, including an increase in the pH value, sorption capacity, macronutrient content, and a decrease in the content and mobility of metals (Cd, Zn, Pb, Cr). The study confirmed the effectiveness of the thermal process on a significant reduction in the ecotoxicity of the sediments, a reduction in total content of elements, and a decrease in their leachability, and thus mobility, with increasing process temperature. The study results revealed that the converted contaminated bottom sediments can be effectively managed, provided that further studies on their technical application are carried out.

The evaluation of Hudson River sediment as a growth substrate - Microbial activity, PCB-degradation potential and risk assessment

The potential use of growth substrates prepared with an admixture of 10% to 75% Hudson River sediments was evaluated by analysis of changes in microbial activity (measured using Biolog Ecoplates) and molecular markers (presence of degradative tceA1 and bphA genes) as well as potential risks toward humans and the environment (health and environmental risk quotients). The highest microbial activity was found in growth substrate with 25% Hudson River sediments compared to unamended control soil. Significant differences were observed between samples amended with lower (0-10%) and higher (25-75%) proportion of sediment. Microbial activity increased with the proportion of sediment amendment (≥25% sediment); however, this increase in microbial activity was not affected by increasing pollutant concentrations (PCBs, Pb, Cr Ni and Zn) nor decreasing TOC content. The growth substrate amended with Hudson River sediments demonstrated a potential for PCB degradation, as evidenced by the presence of tceA1 and bphA genes responsible, respectively, for reductive dehalogenation and oxidation of a range of aromatic organic compounds including PCBs. An assessment of risk quotients showed that the growth substrates containing lower doses of Hudson River sediments (10-50%) meet the international requirements for use in agriculture/horticulture for the production of non-food crops. Nevertheless, due to the elevated content of some toxic metals and PCBs, the growth substrate prepared with the highest proportion of sediments (75%) was not suitable for agricultural/horticultural use.

Enzymatic Activity and Its Relationship with Organic Matter Characterization and Ecotoxicity to Aliivibrio fischeri of Soil Samples Exposed to Tetrabutylphosphonium Bromide

This study aimed to determine the impact of tetrabutylphosphonium bromide [TBP][Br] on the soil environment through an experiment on loamy sand samples. The tested salt was added to soil samples at doses of 0 (control), 1, 10, 100, and 1000 mg kg-1 dry matter (DM). During the experiment, the activity of selected enzymes involved in carbon, phosphorus, and nitrogen cycles, characteristics of organic matter with Fourier-transform infrared (FT-IR) spectroscopy, and toxicity of soil samples in relation to Aliivibrio fischeri were determined at weekly intervals. The results showed that low doses of [TBP][Br] (1 and 10 mg kg-1 DM) did not have much influence on the analyzed parameters. However, the addition of higher doses of the salt into the soil samples (100 and 1000 mg kg-1 DM) resulted in a decrease in the activity of enzymes participating in the carbon and phosphorus cycle and affected the activation of those enzymes involved in the nitrogen cycle. This may be due to changes in aerobic conditions and in the qualitative and quantitative composition of soil microorganisms. It was also observed that the hydrophobicity of soil organic matter was increased. Moreover, the findings suggested that the soil samples containing the highest dose of [TBP][Br] (1000 mg kg-1 DM) can be characterized as acute environmental hazard based on their toxicity to Aliivibrio fischeri bacteria. The increased hydrophobicity and ecotoxicity of the soil samples exposed to the tested salt were also positively correlated with the activity of dehydrogenases, proteases, and nitrate reductase. Observed changes may indicate a disturbance of the soil ecochemical state caused by the presence of [TBP][Br].

Utilization of PCB-contaminated Hudson River sediment by thermal processing and phytoremediation

The need to dispose of dredged sediments and development of appropriate technology for their safe utilization has become a growing problem in recent years. It has been proposed that dredged, fresh sediments can be utilized in agriculture or environment; however there is also growing interest in the use of thermally-treated sediments. Hence, the aim of this study was threefold: 1) to evaluate the effect of two incineration temperatures (300 °C and 600 °C) on the chemical and ecotoxicological properties of sediment; 2) select the appropriate treatment for further phytoremediation experiments with zucchini; and 3) assess the impact of sediment admixture on the physico-chemical parameters of soil, based on the responses of Aliivibrio fischeri and growth of zucchini (Cucurbita pepo L. cv 'Black Beauty'). A range of chemical (inductively-coupled plasma optical emission spectrophotometry for macro- and trace elements; gas chromatography for polychlorinated biphenyls (PCBs)), ecotoxicological (Microtox assay), and plant morphology (biomass measurement) as well as physiological analyses (spectrophotometry for chlorophyll) were applied. River sediments incinerated at 600 °C resulted in better chemical and ecotoxicological properties than incinerated at 300 °C or no incinerated. Incineration at 600 °C removed PCBs from sediment. In culture experiments conducted with zucchini, sediment treated at 300 °C demonstrated a 51-81% reduction in PCB concentrations compared to untreated sediment. After four weeks of growth, the raw sediment showed a significant increase in K, Fe, Cr, Pb, Zn concentrations, whereas the thermally-processed sediment showed a decrease in Ca, Na, P, Cd, Cu, Ni, and Zn concentrations. Both the fresh and thermally-treated sediment types influenced plant growth positively: they demonstrated higher biomass production than plants grown in control soil; however, plants grown on soil with thermally-processed sediment demonstrated lower biomass than those grown in raw sediment. Chlorophyll content was affected negatively by admixtures of soil with treated or untreated sediment, while a lower chlorophyll a/b ratio was observed in plants grown on an admixture of thermally-treated sediment with soil. Our findings suggest that the use of sediments as a growth medium component may be a promising way for their utilization and transformation from waste material to a valuable resource enhancing the benefits to the environment.