A nature-based solution to a landfill-leachate contamination of a confined aquifer

Remediation of groundwater from landfill contamination presents a serious challenge due to the complex mixture of contaminants discharged from landfills. Here, we show the significance of a nature-based solution to a landfill-contaminated aquifer in southeast Norway. Groundwater physicochemical parameters monitored for twenty-eight years were used as a proxy to infer natural remediation. Results show that concentrations of the major chemical variables decreased with time and distance until they tailed off. An exception to this was sulphate, which showed an increase, but apparently, exhibits a stationary phase. The water types were found to be most similar between samples from active landfill and post-closure stages, while samples from the stabilised stage showed a different water type. All the chemical parameters of samples from the stabilised stage were found to be within the Norwegian drinking water standards, except iron and manganese, which were only marginally above the limits, an indication of a possible recovery of this aquifer. The findings highlight the significance of natural attenuation processes in remediating contaminated aquifers and have significant consequences for future contamination management, where natural remediation can be viewed as an alternative worth exploring. This is promising in the wake of calls for sustainable remediation management strategies.

Norwegian Soils and Waters Contain Mesophilic, Plastic-Degrading Bacteria

Plastic pollution has become one of the most critical environmental issues, as rapidly increasing production, compounded by persistence of plastic wastes in the environment, are outpacing efforts to keep ecosystems plastic-free. A switch to plastics more amenable to microbial attack is one of several possible responses. Against this background, the current study describes the isolation, enumeration and polyphasic characterization of plastic-degrading bacteria present in Norwegian terrestrial and aquatic habits. It shows that these bacteria are present in relatively high numbers, and that plastic-degrading capabilities are found in several taxa, most especially Streptomyces. Some isolates wereable to degrade several plastics. Notably, a Rhodococcus sp. and a Streptomyces sp. degraded, respectively, four and six of the eight plastics investigated and a number of other polymers relevant for plastic blends. The paper also has a methodological aspect, presenting various approaches for assaying plastic-degrading properties and a PCR/sequencing-based approach for the identification of potential polyethylene terephthalate-degrading genes. A candidate gene was detected in several Streptomyces isolates. The study shows that Norwegian environments are a rich source of bacteria with the ability to degrade bioplastics possibly representing a natural remediation capacity, as well as a potential source of useful enzymes.

Removal of hexavalent chromium by hyporheic zone sediments in an urbanized estuary

More than 2 million tons of chromium ore processing residue (COPR) waste was disposed of in Hudson County of New Jersey, which was known as the center of the production of chromate in the 20th century. The Cr(VI) removal experiments were conducted with the hyporheic zone (HZ) sediments collected along the shore of an urbanized estuary located in and near Hudson County to investigate the natural remediation of Cr(VI). Fine-grained and organic-rich Passaic River sediments showed the highest removal capacity for Cr(VI), whereas the lowest removal of Cr(VI) occurred in coarse-grained and organic-poor sediments from Newark Bay. In general, Cr(VI) removal increased with higher amounts of sediment organic matter, sulfur, and silt and clay fractions, as well as lower pH conditions. The removal of hexavalent chromium in organic-rich sediments is attributed mainly to the reduction of Cr(VI) to Cr(III), resulting in less reversible immobilization of Cr(VI), while reversible adsorption could also remove Cr(VI). The results suggest that the organic-rich, fine-grained HZ sediments can act as a natural reactive barrier for the remediation of Cr(VI) transport from subsurface to surface water in the estuary. Further research is needed to understand the long-term mobility of Cr along the urban estuary.

Buffer Properties of Heterogeneous Mixtures “Mineral – Natural Waters”

The provision of plants is generally assessed by the potential buffering capacity of soils in relation to the elements of plant nutrition. The main focus in this chapter is to review the developed earlier buffer theory and show how to use the for assessing and predicting the long-term phenomena of attenuation and natural remediation of ionic pollutants in contaminated aquatic ecosystems. The buffer theory is based on the rigorous thermodynamic analysis of complex chemical equilibria under environmental conditions in aquatic ecosystems, developed in the previous chapter. It has been proved that both homogeneous and heterogeneous systems manifest a buffer action towards all their components. It has been established that the buffer capacities of components are mutually proportional, whereas for heterogeneous systems these relationships depend on the stoichiometric composition of solid phases. The use of the developed buffer approach yields deeper understanding of the processes that control the concentrations of various components.

Research of natural remediation of the subsurface contaminated with petroleum products

Remediation of the subsurface contaminated with petroleum products is the ecological problem on a world scale and a foreground direction of geoecological research in Ukraine. Remediation of contaminated vadose zone can be provided with the activity of microorganisms, mainly micromycets, whose features of location and vital activity depend on a depth, the level of contamination, aerobic conditions, etc. Practically, it is complicated to use artificial microbiological methods and natural remediation of contaminated subsurface due to microorganisms should be taken into consideration. Microorganisms oxidizing hydrocarbons are of particular interest. Field investigations were carried out within the fuel storage of the Boryspil airport where subsurface contamination with petroleum products was revealed in 1998. The research included sampling at contaminated and uncontaminated sites, quality analysis of petroleum product contains in soils and determination of the species composition of micromycets. Soil samples were taken in three wells at different depths – in the center of the contamination source at the depths of 0,1 m and 2,0 m (unsaturated zone) and 4,0 m (saturated zone), in the northern part of the fuel storage in the unsaturated zone at the depths of 0,1 m and 1,0 m, and out of the contamination source in the unsaturated zone at the depth of 3,7 m. Fungus culture determination data in soil samples indicate that variety of their forms depends on a contamination degree, a depth of sampling, lithology and water saturation. Regular monitoring should be carried out including soil sampling and determination of petroleum product contains to specify conclusions about natural remediation of contaminated soils due to life activity of microorganisms oxidizing hydrocarbons.

Chemical or Natural? Including LCA in Social CBA to Compare Remediation Alternatives for a Dry-Cleaning Facility

The choice between remediation alternatives for contaminated sites is complicated by different elements, e.g., the occurrence of multiple contaminants, the extent of the contamination, or the urban location, complicate the choice between remediation alternatives. This paper addresses this challenging choice by analyzing a case study of an extensive soil and groundwater contamination by a dry-cleaning company. For remediating this site, two alternatives were proposed. The first remediation alternative combines several techniques with in-situ chemical oxidization being the most important one. Due to the potential negative impact of this alternative on local residents a second remediation alternative was drawn up, in which the focus lies on the use of stimulated biological degradation. A Life Cycle Assessment (LCA) was performed on both alternatives and showed that the second alternative had a lower environmental impact. The inclusion of monetized LCA results in the calculation of a social Cost-Benefit Analysis (CBA) provided a more extensive view of the secondary environmental costs and benefits of the remediation alternatives. The results of the social CBA allow to conclude that both alternatives are not socially desirable, the chemical alternative however is socially less disadvantageous than the more natural remediation alternative.