Soil Contamination Evaluation

🤔 What can #soil #DNA tell us about remediating soil contaminated with petroleum? ⛽ A month back I helped an urban farmer in Richmond VA run a pair of BeCrop samples from soil contaminated with hydrocarbon fuel, one from a plot she had treated for a microbial inoculum advertised to clean up such pollution. 🦠 Aside from the stink dissipating, she wanted insight into the status of the #bioremediation. 🍄 In the unremediated soil, the fungal community was mainly: - 65.4% Thermomyces lanuginosus - lipase-producing fungus that can exploit hydrocarbons as food sources. Their dominance clearly reflects the petrochemical-contaminated environment. (photo 1) - 7.0% Aspergillus fumigatus - Aspergilli are molds, recycling C, N, and other nutrients through decomposition. A. Fumigatus is common in compost and soil. (photo 2) - 5.4% Iodophanus carneus - a decomposer particularly known from dung samples (immature compost?) (photo 3) All told, the fungal community was 96% from phylum Ascomycota. ♻️ What about the treated soil? A full 324 more identifiable taxa were found there. Total fungal sequences increased by an order of magnitude and the ratio of fungal to bacterial sequences increased 50-fold! —> biodiversity, resilience, functionality In remediated soil, the fungal community was much more diverse: - 5.4% T. lanuginosus, way down from 65.4%, suggesting the oil was much diminished as a food source - 45.5% Coprinellus bisporus (only 0.11% before treatment) - an inky-cap mushroom that is associated with normal soils, not contaminated ones, indicating successful remediation (photo 4) - I. carneus increased to 19.2% of sequences - suggests the compost is now the dominant carbon source - 6% Mortierella ambigua (not found in untreated soil) - another class of decomposers. May live on roots and feed on insect exoskeletons. Again, reflects the return of a normal soil community. (photo 5) - Phylum Basidiomycota now constituted 48% of the community rather than 1% - Mortierellomycota were up from 3% to 7% as well 🧬In terms of high-level analysis, the greatest change was a move from the 24th to the 76th percentile in resilience, the ability of a community to recover when stressed by a disturbance like a drought, flood, heat, a pathogen, etc. The other greatest increases were in  - functional biodiversity (35th to 66th percentile) - taxonomic biodiversity (30th to 53rd) - insecticide agents (0th!! to 18th, which suggests insects beginning to recolonize the remediated soil (farmer confirmed) and applying selective pressure) - Moderate 10+ point increases in P & K solubilization, P cycling, Zn, and Mg transport. Two samples do not a controlled experiment make, but I really enjoyed digging through the data and seeing how much unique insight can come out of a simple pair of tests. The farmer is still awaiting results from heavy-metal analysis performed by another lab.

A study of 100 fields reveals that even after 20 years of organic management, soils contain up to 16 different pesticide compounds—disrupting microbial communities and undermining productivity long after application stops. Fields were analyzed across the agricultural spectrum—from conventional operations to established organic farms. Certified organic soils contained significant levels of atrazine, chloridazon, and carbendazim (a compound linked to declining reproductive health). The data contradicts what's on pesticide labels. Atrazine's official half-life (6-108 days) suggests quick breakdown, but field measurements show it persists for decades. Our current models dramatically underestimate how long these compounds actually remain in soil systems. This isn't just about chemical presence—it's about ecosystem function. The study identified a strong negative correlation between pesticide residues and beneficial soil microorganisms. Specifically, mycorrhizal fungi showed significant decline in pesticide-affected soils. A critical insight: pesticide presence better predicted soil biological health than traditional factors like fertilization practices. This suggests our understanding of what drives soil fertility needs revision to account for these long-term chemical impacts. The implications challenge organic certification frameworks, which focus on current management but may overlook historical contamination. A "chemical-free" farm might contain decades of persistent compounds affecting soil function regardless of current practices. Fortunately, biological systems offer powerful remediation solutions: MICROBIAL REMEDIATION: microbes that consume pesticides, enhanced by adding nutrients or introducing specialized degraders ENZYME PATHWAYS that transform compounds into less toxic forms PHYTOREMEDIATION: Plants like Kochia scoparia remediate atrazine through uptake and by stimulating specialized microbial communities at their roots The most effective method is an integrated approach. Plant-microbe partnerships create effective remediation systems where plants fuel microbial activity and microbes enhance plant growth—a synergistic relationship that accelerates cleanup beyond what either could achieve alone. This research challenges the conventional-to-organic transition period. Rather than passive waiting periods, conversion should include active remediation strategies tailored to specific field conditions and contamination profiles. Agricultural soils have much longer chemical memories than previously understood. Biological systems—microbes, enzymes, plants—offer sophisticated remediation pathways that can restore soil ecological function while maintaining productive agricultural systems.

From the Series Collaborations - or how one month of working as a #Fulbright Senior Specialist can lead to many years of collaboration! After spending one month at the National Agrarian University La Molina - Universidad Nacional Agraria La Molina (Lima, Peru) as a Fulbright senior specialist in 2018 at Prof. Javier Arturo Ñaupari Vásquez's invitation, the opportunities to collaborate have continued. Not only did we collaboratively win two World Bank (Concytec Perú) awards, but we have continued to work together for the last 6 years in various ways, including publications. In this new publication led by Samuel Edwin Pizarro in Geoderma, we explored soil contamination in the Peruvian Mantaro Valley, a vital agricultural region, using advanced geospatial and machine learning techniques. We mapped the presence of 25 metals and metalloids, including arsenic (As), lead (Pb), and cadmium (Cd), which often exceeded safe levels. These elements pose significant risks to human health and ecosystems, particularly when they accumulate in soils used for growing food crops. By combining soil samples with environmental data such as climate, topography, and satellite imagery, we created high-resolution predictions of contamination across the region. Our findings reveal hotspots of contamination, primarily near rivers and roads, influenced by human activities like mining, industrial operations, and agriculture. This work demonstrates the importance of understanding the spatial distribution of contaminants to prioritize clean-up efforts, improve regulations, and ensure safe food production. We contribute to advancing soil mapping techniques and emphasize the need to address soil contamination for the protection of public health and the sustainability of agricultural systems. Link to the open paper here: https://lnkd.in/gbSDGQfU #SoilHealth #EnvironmentalProtection #GeospatialScience #MachineLearning #AgricultureSustainability #SoilContamination #FoodSecurity #ToxicMetals #SustainableFarming #ClimateResilience #DigitalMapping #Peru #SoilScience #DataDrivenSolutions #MaroonResearch

🌍 Our new article is out in SOIL (European Geosciences Union (EGU) journal): “Portable X-ray fluorescence as a tool for urban soil contamination analysis: accuracy, precision, and practicality.” 🔗 Read here: https://lnkd.in/gbMuscqW Led by my former student, Eriell Jenkins from UL Lafayette School of Geosciences, and supported by USDA NRCS, this review brings together 84 studies on the use of portable X-ray fluorescence (PXRF) for measuring heavy metal(loid) contamination in urban soils. Some takeaways we highlight: 🔭 PXRF works as a rapid, cost-effective tool for screening contaminants like Pb, As, Cr, Ni, Cu, and Zn. 🔭 Calibration matters — using certified reference materials and considering soil matrix effects improves reliability. 🔭 Method tweaks help — even the choice of sample bag can reduce errors, especially for lighter elements. 🔭 Ex situ analysis improves precision, but in situ PXRF is practical and valuable for urban soil assessments. This work shows how PXRF can help communities, researchers, and practitioners map contamination hotspots faster and make urban agriculture safer. Grateful to USDA NRCS for supporting this project and to our co-author John Galbraith for his thoughtful contributions. #SoilScience #UrbanSoils #PXRF #SoilContamination #SoilHealth #UrbanAgriculture #EnvironmentalHealth #USDANRCS

Contaminants are typically studied one chemical at a time. However, real world situations endure mixtures of dozens to thousands... For instance, how well does single-species predictions hold up when dozens of PFAS compounds, pharmaceuticals, and/or hydraulic fracturing chemicals contaminate a soil profile? And what happens when those mixtures interact... competing for sorption sites, altering each other's mobility, transforming into products we aren't even monitoring? In this new review article in the Journal of Environmental Quality, I examine this disconnect for three classes of emerging contaminant mixtures in soils and vadose zones: - PFAS - Pharmaceuticals and personal care products (PPCP) - Hydraulic fracturing fluid additives and contaminants (HFFA-HFFC). All three enter the environment as complex mixtures, not isolated species. Yet most transport research and risk frameworks are built on single-species experiments. Some select points: 👉 Mixture effects consistently cause transport behaviors that diverge from single-species predictions. Competitive sorption can enhance mobility for some compounds while reducing others, creating chromatographic separation with depth. 👉 Vadose zones function as persistent secondary sources, sustaining groundwater contamination for decades. Removing dissolved groundwater contamination without addressing vadose zone sources will likely prove ineffective for long-term plume control. 👉 Transient saturation conditions can enhance contaminant transport by an order of magnitude relative to constant-flow predictions. Whereas, most laboratory studies use steady-state conditions. 👉 Current risk assessments implicitly assume independence among mixture components. Toxicological studies consistently demonstrate that this assumption does not hold. The review identifies six priority research areas: - Mixture sorption and competitive transport - Transformation products and reaction pathways - Field-scale validation - Multi-mechanism remediation - Integrated mixture toxicity assessment - Climate change impacts on mixture dynamics The gap between how we study these chemicals and how they actually behave is one we can close, but it requires a deliberate shift and investment toward mixture-based research frameworks. 🔓 Full open-access article: https://lnkd.in/eprtyAnW #VadoseZone #PFAS #SoilScience #Groundwater #EmergingContaminants #EnvironmentalScience Nebraska Agronomy & Horticulture UNL Biological Systems Engineering University of Nebraska-Lincoln University of Nebraska Medical Center