Research & reports

Candice M. Duncan, Fatemeh Ghezelsofla, Hlengilizwe Nyoni, Jazmin Escobar, Odette Mina · Toxics · United States

A study measuring per- and polyfluoroalkyl substances (PFAS) in irrigation water at two organic farms in Maryland, USA, with no known direct PFAS input, and assessing health risk via a Hazard Index (HI). At agricultural site 1 (AG1), the most abundant compounds were PFBS (37 ng/L), PFBA (24 ng/L) and PFHxA (22 ng/L); the HI showed compliance for branched PFHxS (0.39) but non-compliance for linear PFHxS (1.51). At agricultural site 2 (AG2), despite no known industrial or PFAS-related facilities nearby, HFPO-DA (GenX) was detected at 28 ng/L, and the HI exceeded the compliance threshold (HI = 2.83), with GenX accounting for most of the calculated risk. The findings show HI exceedances occurring at small farm sites with no identifiable contamination source.

Jordi Guimera Garcia, Natalie Bray, Yowhan Son, Aleah L. Butler-Jones, Sara Perl Egendorf, Jenny Kao‐Kniffin · Journal of Urban Ecology · United States (New York City)

In New York City, a study investigated plant growth (tomato, pepper, kale) in soils constructed from four municipal composts mixed with sediments from the NYC Clean Soil Bank, to assess the potential for safe urban agricultural soils. While Clean Soil Bank sediments enhanced plant growth when mixed with BRL compost, they also negatively impacted tomato aboveground biomass production by 29% in LES compost and tomato plant height by 18% in QBG compost, indicating variable effects depending on compost properties.

James D. Blount, Leah E. K. Lenoch, Faith A. Fitzpatrick · Journal of Great Lakes Research · United States

A study of Apple Creek, Wisconsin (119 km²), a Great Lakes tributary like many others subject to Total Maximum Daily Load (TMDL) targets requiring reductions of 51.2% in suspended sediment and 64.2% in total phosphorus. From August 2017 to October 2018, an integrated stream sediment budget and fingerprinting study quantified upland and stream-corridor sources of suspended sediment and sediment-bound phosphorus. Phosphorus concentrations varied among source groups and fluvial sediment types, with higher concentrations in suspended sediment and cropland soils. Eroding streambanks accounted for 100% of the TMDL model's (SWAT) suspended sediment load but only 20% of the total phosphorus load; fine-grained streambed sediment equated to roughly three years of modelled suspended sediment load but only one-third of the total phosphorus load. The two primary sources of fine-grained streambed sediment were streambanks and cropland, with the relative streambank contribution increasing downstream and with watershed area. The relative proportion of suspended sediment varied by season and streamflow, but weighted for representative streamflow, cropland and streambank erosion accounted for 54% and 23% of suspended sediment respectively. Urban land was a source in the upper watershed, but its signature was sequestered by a mid-watershed detention basin, and contributions from construction sites were higher in fall 2018, likely corresponding to increased activity following a wet spring.

Moisés Savian, Mari Inês Caríssimi Boff, Pedro Boff · Cadernos de Agroecologia · Brazil

This study evaluated Brazilian scientific production from 2009 to 2018 on urban agriculture's contribution to food and nutritional security, analyzing 34 selected articles out of 612. It found that while agrobiodiversity is present in urban agriculture areas, pesticide use is a reality in some crop plots. The research suggests urban agriculture must be based on agroecology to avoid environmental contamination and produce healthy food.

Elizabeth A. Miernicki · Illinois Digital Environment for Access to Learning and Scholarship (University of Illinois at Urbana-Champaign) · United States

A study from the University of Illinois at Urbana-Champaign, USA, that identifies soil contamination as a universal concern in urban agriculture and notes that the long-term benefits of alternative soil management systems such as raised beds have not been explored in the scientific literature. Its stated objective is to determine the effects of six soil management options - direct soil with synthetic fertilizer (DSF), direct soil with organic amendments (DSO), raised-bed mixture with synthetic fertilizer (RBMF), raised-bed mixture with organic amendments (RBMO), raised-bed compost-only with synthetic fertilizer (RBCF), and raised-bed compost-only with organic amendments (RBCO) - on yield of kale, garlic, pepper, cilantro and radish, on soil biological, chemical and physical properties, and on ecosystem services such as water and nutrient retention. Data collected include marketable versus cull yield, soil nutrients and organic matter, soil moisture, weed emergence, infiltration rate and bulk density, but this abstract does not report the comparative results themselves.

B.M. Mercado-Borrayo, Silke Cram Heydrich, Irma Rosas‐Pérez, Manuel Hernández Quiroz, Claudia Ponce De León Hill · International Journal of Phytoremediation · Mexico

In a natural wetland in the Mexico City Metropolitan Area — a major supplier of crops and flowers whose canals hold high concentrations of organochlorine (OC) and organophosphorus (OP) pesticides — bioaccumulation of these pesticides was studied in water hyacinth (Eichhornia crassipes), a plant considered a plague but suggested in the literature to have phytoremediation potential. In vivo bioaccumulation differences for OC pesticides were largely explained by their log Kow, while all OP pesticides showed bioaccumulation regardless of log Kow, and the higher bioaccumulation factors of some accumulated OC pesticides could not be explained by log Kow alone, suggesting passive transport into the plant. Translocation ratios showed water hyacinth to be an accumulating plant with phytoremediation potential for all the organophosphorus pesticides studied and some organochlorine pesticides, and an equation for free water surface wetlands with floating macrophytes showed pesticide removal by the wetland with room for improvement through better management.

Josh Beniston · The Knowledge Bank (The Ohio State University) · United States (Ohio)

An experiment on assessing and managing soil quality for urban agriculture was conducted during the 2011 and 2012 growing seasons on demolished vacant urban lots in Youngstown, Ohio. Soil compaction was identified as a primary constraint, with high bulk density values of 1.79 g cm⁻³ for in-ground plots and 1.55 g cm⁻³ for raised beds. Crop yield data from 2011 showed that both compost-amended and compost + biochar-amended plots had significantly greater crop yields than control plots, with compost + biochar plots achieving the highest harvest index values.

Saad El‐Din Hassan, Eva Boon, Marc St‐Arnaud, Mohamed Hijri · Molecular Ecology · Canada

A study assessing indigenous arbuscular mycorrhizal fungi (AMF) community structure in roots and soil of Plantago major (plantain) growing on trace-metal (TM)-contaminated versus uncontaminated sites, selected based on a survey of TM concentrations (As, Cd, Cu, Pb, Sn, Zn) in community garden soils in Montreal, Canada. AMF community structure was analyzed using PCR-DGGE, cloning and sequencing, and direct sequencing. Native AMF diversity, measured by the number of AMF ribotypes, was decreased in TM-polluted soils and plant roots compared with unpolluted sites, and community structure was altered by TM contamination. Various Glomus species along with Scutellospora aurigloba and S. calospora were the most abundant ribotypes in unpolluted soil, while G. etunicatum, G. irregulare/G. intraradices and G. viscosum occurred in both polluted and unpolluted soils, and G. mosseae together with unidentified Glomus ribotypes (B9, B13) dominated in TM-polluted sites. The predominance of G. mosseae at metal-polluted sites is interpreted as suggesting tolerance to TM stress and potential use for phytoremediation.