Aquatic ecosystems in mountainous regions are crucial for fulfilling natural and anthropogenic water demands around the world. This study integrates Escherichia coli (E. coli) enumeration, microbial source tracking (MST), and environmental DNA (eDNA) analysis to identify sources of fecal contamination in oligotrophic mountain waters. Conducted in an area with intense tourism and traditional reindeer herding, this research addresses the urgent need to identify fecal pollution sources to safeguard the water quality of these vital ecosystems. Our study reveals that E. coli levels vary significantly across different locations and times, suggesting varied sources of contamination from humans, wildlife, and livestock animals. MST techniques, alongside eDNA analysis, provided insights into the complex patterns of fecal pollution, allowing for the distinction between human and animal contributions to water contamination. Our findings highlight the importance of combining various analytical methods to track fecal pollution sources effectively, and to develop targeted strategies for water quality management.

Wastewater discharges from the old pulp and paper industry led to the accumulation of contaminated wood pulping fibers and debris—referred to as fiberbanks (FB)—in the Baltic Sea and freshwater bodies across Sweden and other pulp-producing countries. These anthropogenic sediments are polluted with toxic metal(oid)s and persistent organic pollutants, and their decomposition releases greenhouse gases. Phytoremediation offers a nature-based solution for the ex-situ treatment of these fibrous sediments, but they present unique challenges due to the abundant and unstable organic matter and aged pollution. This study aims to identify potential plant candidates and to address the limitations of fiberbanks as a plants growing media for phytoremediation. In a greenhouse experiment, we assessed the performance of five plant species (Brassica juncea, Brassica napus, Helianthus annuus, Hordeum vulgare, and Poa annua) grown in substrates formulated with fiberbank. The evaluation included plant growth parameters, bioconcentration and uptake efficiency of metal(oid)s (V, Cr, Co, Ni, Cu, Zn, As, Cd, and Pb), and the degradation of polycyclic and linear hydrocarbons. Despite initial concerns, fiberbanks displayed favorable physical characteristics and a degree of fertility conducive to plant growth. Even though all tested species seeds could cope with fiberbanks acute toxicity, H. vulgare and P. annua showed better tolerance to the fiberbanks substrates and superior aerial biomass development, which promoted a highest toxic metal(oid)s uptake efficiency, regardless of lower bioconcentration factors for most of the target elements. Zn (17.16–23.25 mg/kg of FB), Cu (4.18–6.48 mg/kg of FB) and Cr (1.05–1.36 mg/kg of FB) were most effectively taken up by these plants. The uptake of Co (0.04–0.18 mg/kg of FB) and Ni (0.05–0.17 mg/kg of FB) was lower. As (0.01–0.02 mg/kg of FB), Cd (0.02–0.06 mg/kg of FB), Pb (0.02–0.04 mg/kg of FB) and V (0.02–0.03 mg/kg of FB) phytoextraction was not significant. None of the species exhibited a significant removal of targeted organic pollutants. Phytoremediation, either on its own or in combination with other strategies, shows promise for the remediation of fiberbanks. However, further research is needed to understand how the organic matrix and long-term underwater aging of fiberbanks affect pollutants bioavailability.

ABSTRACT Microbial source tracking leverages a wide range of approaches designed to trace the origins of fecal contamination in aquatic environments. Although source tracking methods are typically employed within the laboratory setting, computational techniques can be leveraged to advance microbial source tracking methodology. Herein, we present a logic regression-based supervised learning approach for the discovery of source-informative genetic markers within intergenic regions across the Escherichia coli genome that can be used for source tracking. With just single intergenic loci, logic regression was able to identify highly source-specific (i.e., exceeding 97.00%) biomarkers for a wide range of host and niche sources, with sensitivities reaching as high as 30.00%–50.00% for certain source categories, including pig, sheep, mouse, and wastewater, depending on the specific intergenic locus analyzed. Restricting the source range to reflect the most prominent zoonotic sources of E. coli transmission (i.e., bovine, chicken, human, and pig) allowed for the generation of informative biomarkers for all host categories, with specificities of at least 90.00% and sensitivities between 12.50% and 70.00%, using the sequence data from key intergenic regions, including emrKY–evgAS , ibsB–(mdtABCD-baeSR), ompC–rcsDB, and yedS–yedR , that appear to be involved in antibiotic resistance. Remarkably, we were able to use this approach to classify 48 out of 113 river water E. coli isolates collected in Northwestern Sweden as either beaver, human, or reindeer in origin with a high degree of consensus—thus highlighting the potential of logic regression modeling as a novel approach for augmenting current source tracking efforts. IMPORTANCE The presence of microbial contaminants, particularly from fecal sources, within water poses a serious risk to public health. The health and economic burden of waterborne pathogens can be substantial—as such, the ability to detect and identify the sources of fecal contamination in environmental waters is crucial for the control of waterborne diseases. This can be accomplished through microbial source tracking, which involves the use of various laboratory techniques to trace the origins of microbial pollution in the environment. Building on current source tracking methodology, we describe a novel workflow that uses logic regression, a supervised machine learning method, to discover genetic markers in Escherichia coli , a common fecal indicator bacterium, that can be used for source tracking efforts. Importantly, our research provides an example of how the rise in prominence of machine learning algorithms can be applied to improve upon current microbial source tracking methodology.

Soil pollution is a threat to food security and ecological and human health. Cd is one of the most common pollutants in agricultural soil and, due its human toxicity, one of the most hazardous. Amaranth is a documented hyperaccumulator of Cd and other pollutants, and it is commonly grown in Asia and South America. A considerable amount of amaranth is grown in suboptimal conditions, including nutrient-poor acidic soils. The objective of this experimental study was to examine the capacity of Amaranthus hypochondriacus to extract Cd from a nutrient-poor, acidic substrate that was spiked with different concentrations of Cd (2 and 20 mg kg−1 dw) during a period of 180 days. The plants grown in the substrate that was spiked with 20 mg Cd kg−1 dw did not develop into mature plants, but the plants grown in substrate that was spiked with 2 mg Cd kg−1 dw extracted a significant amount of Cd from the substrate by accumulating it into the above-ground biomass. The Cd levels varied from 113 to 176 mg kg−1 in the stems at the four measuring points, and from 64 to 94 mg kg−1 in the leaves. The concentrations in the plants increased with time and reached a maximal concentration of 176 ± 45 mg kg−1 dw for stems and 94 ± 41 mg kg−1 dw for leaves after 180 days. The mean bioaccumulation factor in the plants was 86 ± 15 after 90 days, 72 ± 12 after 120 days, 105 ± 37 after 150 days, and 99 ± 31 after 180 days, which confirms the previously reported capacity of Amaranthus hypochondriacus to hyperaccumulate Cd. Amaranthus hypochondriacus may, thus, be used to improve ecological and human health by remediating moderately Cd-polluted soils, even in nutrient-poor acidic soils.

Pulp and paper production is one of the largest global industries producing annually 400 million metric tons of pulp and paper products and 6 million tons of pulp and paper biosludge (PPBS). From a resource efficiency and sustainability perspective, there is a need for improving PPBS management. This study assessed fermentation of PPBS as pretreatment to improve PPBS feasibility as feed for black soldier fly larvae. The impact of temperature, pH, and inoculum on the concentration of soluble chemical oxygen demand (sCOD) and volatile fatty acids (VFA) was assessed. An initial pH of 10 and the addition of inoculum from an anaerobic digester substantially increased the concentration of sCOD. The obtained concentration of VFA was low compared to the VFA concentration needed to improve the growth of Black Soldier Fly Larvae (BSFL). The PPBS is recalcitrant to fermentation because of the high content of lignocellulose. Fermentation as done in this study does not convert PPBS to a feasible feed for black soldier fly larvae; thus, further research on improved fermentation is needed. However, fermentation at alkaline pH and addition of inoculum do increase the final pH of PPBS which improves its feasibility as feed for BSFL. Future studies should explore pH > 10 and temperatures > 55 °C to increase sCOD and improving generation of VFA by removal of inhibiting substances, testing other types of inoculum (rumen microorganisms) and co-fermentation.

This study evaluates the use of fermentation to increase nutrient availability in pulp and paper bio-sludge (PPBS) as feed for black soldier fly larvae (BSFL). Rearing of BSFL on fermented PPBS was carried out in a climate chamber in order to assess nutrient availability and larvae survival and growth. The PPBS used came from a chemo-thermomechanical pulp/groundwood pulp mill. The PPBS was fermented at 35 °C and 55 °C, respectively, at initial pH of 10. The effects of sediment and liquid from fermented PPBS on larvae dry weight, survival rate until the prepupae stage, bioconversion, and reduction rate of PPBS were measured. The bioconversion of the liquids (4.1–6.6%) was substantially higher than for both the sediments and untreated PPBS (≤ 0.4%). The survival rate, on the other hand, was substantially lower (26.3–30.9 %) than for the sediments and untreated PPBS (49.5–52.6%). Neither the sediments nor the liquids had significant effects on the larvae weight or on the PPBS reduction rate. The sediments had no significant effect on the survival rate or the bioconversion. This study demonstrates that fermentation dissolves a part of the PPBS and that dissolved substances in the fermentation liquid readily convert to larvae biomass. However, the bulk of the lignocellulose is not dissolved, and most of PPBS nutrients remain unavailable for growth of the larvae. Further research should focus on improved pretreatment of PPBS to increase availability of nutrients and thereby improve the feasibility of BSFL as a recycling method for PPBS.

Global sustainability challenges associated with increasing resource demands from a growing population call for resource-efficient land-use strategies that address multiple sustainability issues. Multifunctional agroforestry-based phytoremediation (MAP) is one such strategy that can simultaneously capture carbon, decontaminate soils, and provide diverse incomes for local farmers. Chinandega, Nicaragua, is a densely populated agricultural region with heavily polluted soils. Four different MAP systems scenarios relevant to Chinandega were created and carbon sequestration potentials were calculated using CO2FIX. All scenarios showed the potential to store significantly more carbon than conventional farming practices, ranging from 2.5 to 8.0 Mg CO2eq ha−1 yr−1. Overall, carbon sequestration in crops is relatively small, but results in increased soil organic carbon (SOC), especially in perennials, and the combination of crops and trees provide higher carbon sequestration rates than monoculture. Changes in SOC are crucial for long-term carbon sequestration, here ranging between 0.4 and 0.9 Mg C ha−1 yr−1, with the most given in scenario 4, an alley cropping system with pollarded trees with prunings used as green mulch. The adoption rate of multifunctional strategies providing both commodity and non-commodity outputs, such as carbon sequestration, would likely increase if phytoremediation is included. Well-designed MAP systems could help reduce land-use conflicts, provide healthier soil, act as climate change mitigation, and have positive impacts on local health and economies.

Increasing pollution levels in waters from remote mountain areas in northern Sweden have been observed. To support a sustainable water quality management, it is necessary to know which environmental and antrophogenic factors influence the water quality. The purpose of this study was to map the Escherichia coli prevalence in the catchment area of the upper part of a large northern Scandinavian river and investigate the controlling factors of microbial contamination. A total of 112 water samples were collected from various locations in the research area between July 2020 and December 2020. These samples were analyzed for microbial and chemical characteristics, and information about tourism and reindeer herding was compiled. Additionally, microbial and physicochemical water characteristics collected by Indalsälven Water Conservation Association (IWCA, 1993–2020) and Swedish Meteorological and Hydrological Institute (SMHI, 2004–2020) were analyzed. The results showed that E. coli enumerations ranged between 0 and 500 CFU/100 ml. There was generally no obvious relation between suspected point sources, e.g., sewage treatment plants at mountain stations, and E. coli levels at downstream sampling points. Principal component analysis showed that E. coli was correlated to coliforms, total heterotrophic count, river discharge, CODMn and river color. Since microbial analyses are time-consuming, expensive and difficult to perform in remote areas, it is important to find more easily extracted water parameters that can serve as a proxy for E. coli. In particular, river color and discharge are promising parameters that may serve as an early indication of bacterial outbreak and fecal contamination in mountain waters.

Fiberbanks from the pulp and paper industry are typically contaminated with a wide range of chlorinated aromatic and aliphatic toxins such as HCB and other chlorinated benzenes, PCB, HCH, DDT, PCDD, PCDF and Chlorophenols. This poses a formidable challenge for the analyst to develop appropriate analytical methodology for the monitoring of the progress of remediation.In preparation to this undertaking, an examination of a practical analytical method using one extraction method, one clean-up and one analysis method for the aforementioned target compounds found in the fibrous sediment. This method was performed using accelerated solvent extraction (ASE), a modified silica gel column and GC-FID/ECD. Additionally, an assessment of the levels of organic pollutants was conducted, with the purpose of measuring the potential alteration in contaminants when freeze-drying, air-drying and autoclaving pretreatments are applied to the sediment samples, prior to be used as a media for biological remediation.The results showed that the ASE is a very fast and reliable method of extraction, with yields comparable or higher than the reference Soxhlet extraction method. The activated silica gel column demonstrated adequate purification of the sediment extract for analysis using the two detectors, FID and ECD, which were able to identify the target analytes from only one purified extract. The method employed in this study has the potential to reduce both processing time and material used for analytical sample preparation. Lastly, some modifications in concentrations and distribution of target analytes were revealed in the sediments pre-treated by autoclave and air-dried when compared with the freeze-dried sediments, which can help understanding the development of the biological remediation process.

Many coastal areas in Sweden are contaminated with fiber-rich sediments from pulp and paper industry. These fiber-rich sediments are referred to as “fiberbanks” and contains lignocellulosic materials, persistent organic pollutants (POPs) and toxic elements (metals/metalloids). POPs are long-lasting, highly toxic chemicals, and resistant to natural environmental degradation. In the case of exposure to people, POPs can cause serious health problems such as cancers, congenital anomalies, and immune system failure.Bioremediation is a very effective, environmentally friendly and, cheap way of removal of contaminants, pollutants, and toxins. Due to the properties fungi possess (such as mycelia structures and secreted enzymes), using fungi for bioremediation (mycoremediation) attract attention by their ability to degrade and/or accumulate toxins. White rot (wood-decay) fungi have the ability to biodegrade POPs, uptake metals/metalloids, and use lignocellulosic material as a carbon source.In this work, twenty species of white-rot fungi naturally growing in Sweden will be tested for their ability of biodegrade POPs, and bioaccumulation of metals/metalloids. Fiberbanks were collected from Ortviken (Sundsvall Bay-Vasternorrlands). The fungi grow on a small hagem-agar disc with fiberbanks around it. The growth rate of the fungi is recorded with a camera and the circular growth is measured. After two months of growth, POPs degradation will be analyzed by gas chromatography-mass spectrometry (GC-MS) and metal uptaking by high-resolution scanning electron microscopy (HI-SEM).

In the last century, unregulated wastewater discharge from the vigorous Swedish pulp and paper industry has led to the creation of large deposits of fibrous sediments on the Baltic Sea floor, lakes and rivers throughout Sweden. Fibrous sediments comprise: fiberbanks” (fibrous residues and wood chips) and “fiber-rich sediments” (naturally deposited sediments mixed with fibrous residues). Fibrous sediments are mostly polluted by toxic elements (metals and metalloids) and persistent organic pollutants (PCBs, chlorinated pesticides & PAHs, among others), and they are often located in shallow waters, entailing a serious threat both to human and ecological welfare.BioRem Fiber is a public-private partnership research project, whose main goal is to develop methods for the biological remediation of dredged fibrous sediments and the reuse of detoxified materials for market-adapted processes and products. Phytoremediation is one of the technologies to be tested. As far as we know, there is no references in the scientific literature about the use of plants for the remediation of fibrous sediments. Thus, several questions need to be answered before going to the next level: Which plants can be used for fibrous sediments phytoremediation, since it is a multi-elemental and POPs polluted material? How toxic are these sediments for the selected plants? Will these plants grow properly in a potting media prepared with fiberbanks and efficiently remove or degrade target pollutants? To look for answers, we have developed a stepwise plant screening study, consisting of a profuse literature survey for plants selection, an acute fiberbanks toxicity test on selected plant seeds, and a greenhouse bench-scale experiment to assess plants growth and development in soilless potting media prepared with the polluted material. Subsequently, the task will be to unravel toxic elements removal efficiency and the probability of reaching target organic pollutants degradation during plant growth in fiberbanks.

Innumerable private households and small-scale producers currently operate on polluted soils. Phytoremediation is one of the most cost-effective remediation options but as a stand-alone technology, it is often not lucrative enough to make it appealing for farmers, especially in economically vulnerable regions. Economic incentives are crucial for remediation projects to materialise and synergies can be obtained by integrating phytoremediation with other profitable activities including food production. This review aims to synthesise state-of-the-art scientific data to provide a general understanding of opportunities and risks for sustainable remediation of agricultural soil by the use of combined phytoremediation and food production (CPFP). The results show that strategies based on CPFP may be appropriate options for most pollutants in virtually all climatic or socioeconomic contexts but a number of challenges need to be surpassed. The challenges include remediation-technological issues such as undeveloped post-harvest technology and inadequate soil governance. The need for remediation solutions for polluted fields is increasingly urgent since many farmers currently operate on polluted land and the scarcity of soil resources as the human population continuously increases will inevitably force more farmers to cultivate in contaminated areas. We conclude that, although large scale CPFP has not yet reached technological maturity, appropriate combinations of soil types, plant species/cultivars, and agronomic practices together with thorough monitoring of the pollutants’ pathways can potentially allow for safe food production on polluted soil that restricts the transfer of a number of pollutants to the food chain while the soil pool of pollutants is gradually reduced.

Environmental governance is a challenge for many developing countries, and soil pollution is typically overlooked by authorities in the Global South. Soil governance should protect people and envir ...

Polluted land in marginalized regions, such as tropical low-income countries and sparsely populated regions in industrialised countries, demand special remediation strategies that are energy-efficient, locally adapted, economically viable. Strategies for appropriate bioremediation technology under such circumstances can be based on locally available resources in combination with in situ bioremediation technologies to keep energy and material costs down. A pilot scale experiment was set up to test the application of three organic by-products from the local industry (whey, pyroligneous acid and compost tea) to enhance the natural biodegradation of diesel in ultisol. Biweekly applications of 6 mL whey kg−1 soil significantly increased the degradation rate but no positive effect on degradation was found with any of the other amendments. Tropical climate is favourable for biodegradation but many tropical soils are rich in clay which can inhibit the bioavailability of the pollutant which in turn may be decisive for biodegradation kinetics. If low cost is a crucial factor, our results indicate that whey treatment has the potential to be an appropriate technology for treating petroleum-contaminated soils in tropical regions.

Phytoremediation and Agroforestry- mitigation of climate change, poverty reduction and cleaning of soils

Pulp and paper bio-sludge (PPBS) has low economic value and is therefore often composted or incinerated. The purpose of this work is to evaluate the feasibility of using PPBS to breed black soldier fly ( Hermetia illucens ) larvae (BSFL), so improving resource efficiency and supplying protein and fat to the animal feed market. BSFL were reared on PPBS in a climate chamber on a laboratory scale in order to assess nutrient deficiency, inhibition and whether the BSFL recycle the PPBS well or not. The PPBS used came from a chemi-thermomechanical pulp/groundwood pulp mill. The effect of supplementing nutrient solution added either into the PPBS or as a free liquid surface were studied. Prepupae dry weight, survival rate until prepupae stage and residual dry PPBS were measured. The addition of reference diet leachate into the PPBS did not have a significant impact on the weight of the prepupae (2.0 mg) but the survival rate was significantly higher (16.0%). On the other hand, the addition of reference diet leachate as a free liquid surface had a significant impact on both the weight of the prepupae (4.8 mg) and the survival rate (25.7%). The bio-conversion and PPBS—reduction was as best 0.4 and 3.2% respectively. This study has proven that the nutrients in PPBS are not readily available to the larvae. Addition of reference diet leachate increase the survival rate which opens up for possibilities of co-digestion. However, it is clear that under the tested conditions, BSFL is not recycling PPBS well and BSFL as a method for recycling of PPBS need further research. Graphic Abstract

Carbon dioxide (CO2), as one of the major anthropogenic greenhouse gases, is widely acknowledged to contribute to global warming and climate change. Historically, the major focus on the role of the aquatic environment in the carbon cycle has been on the atmosphere-ocean exchange. More recent findings suggest the importance of freshwater (lakes, rivers and streams) as a source for atmospheric CO2. The freshwater contribution is, however, poorly understood, mainly due to a paucity of data, especially from running waters. To address this issue, eddy covariance (EC) measurements in a large boreal river in Northern Sweden (Indalsalven), are being made as part of a two-year long continual study of the carbon dioxide fluxes between the air and water. This is one of the first known studies of its kind where EC measurements are conducted in a river setting. Continual data acquisition began in April 2018, monitoring a variety of general meteorological parameters, turbulent fluxes of carbon dioxide, latent, and sensible heat, together with water-side measurements of CO2. The aim of the study is to investigate the temporal control on river carbon dioxide fluxes covering timescales from hours to seasons. This paper describes the ongoing work, and reports on the present status of the project. The primary focus lies on data that indicates a dependence of carbon dioxide flux on wind-speed. Wind speed demonstrates a positive correlation with the measured fluxes, with the highest fluxes measured corresponding to the directions where the upwind distance to land was greatest, indicating that the wind-generated turbulence has a strong influence on the carbon dioxide fluxes over a boreal river.

Spillage of diesel oil and other petroleum products is a commonly creating need for site remediation of contaminated soils. In Sweden the most common remediation action is excavation of the contaminated soil and off site biological treatment by composting. However, a number of small sites spread out in rural areas end up low on priority lists, and will not be attended to within foreseeable future if ever. For such areas a low cost, easy to apply remediation techniques would be of interest. Enhanced bioremediation of diesel contaminants in soil by whey addition has been demonstrated in lab scale. Whey is a by-product from cheese production. A first pilot remediation trial on an actual site in Gäddede, County of Jämtland, was started the summer of 2010. Using this site as a case study a screening life cycle assessment model has been set up. The goal of the study was to investigate the environmental performance of the whey method, to benchmark the whey method toward the excavation and composting practice and to identify environmental hot spots in the whey treatment life cycle. The study aims at establishing if further work should be put into developing the method, or if the environmental performance is such that the whey method should be abandoned. It should be noted that even with a slightly worse environmental performance compared to other remediation alternatives whey treatment could still be of interest, since the small scale sites in rural areas we talk about here otherwise most often would not be attended to. Results from the screening life cycle assessment indicate a rather good environmental performance of the whey method, partly depending on impact category considered. For the whey method, impacts from farming activities in the milk production chain allocated to the whey give significant contributions. Transportation gives important impacts from both the whey method and the excavation and off site composting, thus logistics should always be considered and optimized. The whey onsite treatment could be an interesting alternative for bioremediation especially at sites that would not otherwise be treated, due to small size or remote location.

Amaranth for phytoremediation of toxaphene-contaminated soil in Nicaragua - assessment of translocation in three cultivars

Soil pollution by pesticides is a serious problem, especially in developing countries where incentives are limited to remediate these soils. Toxaphene was a widely used insecticide during the 1950s ...