Anthropogenic activities profoundly impact soil organic carbon (SOC), affecting its contribution to ecosystem services such as climate regulation. Here, we conducted a thorough review of the impacts of land-use change, land management, and climate change on SOC. Using second-order meta-analysis, we synthesized findings from 230 first-order meta-analyses comprising over 25,000 primary studies. We show that (i) land conversion for crop production leads to high SOC loss, that can be partially restored through land management practices, particularly by introducing trees and incorporating exogenous carbon in the form of biochar or organic amendments, (ii) land management practices that are implemented in forests generally result in depletion of SOC, and (iii) indirect effects of climate change, such as through wildfires, have a greater impact on SOC than direct climate change effects (e.g., from rising temperatures). The findings of our study provide strong evidence to assist decision-makers in safeguarding SOC stocks and promoting land management practices for SOC restoration. Furthermore, they serve as a crucial research roadmap, identifying areas that require attention to fill the knowledge gaps concerning the factors driving changes in SOC.

Fougerite (IMA 2003-057) is a mixed M(II)-M(III) hydroxysalt of the green rust group, where M(II) can be Fe or Mg, and M(III) is Fe. The general structural formula is: [Fe1−2+xFex3+Mgy(OH)2+2y]+x[x/nA−n.mH2O]−x where A is the interlayer anion and n its valency, with 1/4 ≼ x/(1+y) ≼ 1/3 and m ≼ (1−x+y). The structure of green rusts and parent minerals can accommodate a variety of anions, such as OH⁻, Cl⁻, CO32−,SO42−${\rm{CO}}_3^{2 - },\;{\rm{SO}}_4^{2 - }$ . The structure of the mineral was studied by Mössbauer, Raman and X-ray absorption spectroscopies (XAS) at the FeK edge. Mössbauer spectra of the mineral obtained at 78 K are best fitted with four doublets: D1 and D2 due to Fe²⁺ (isomer shift δ ≈ 1.27 and 1.25 mm s⁻¹, quadrupole splitting ΔE_Q ≈ 2.86 and 2.48 mm s⁻¹, respectively) and D3 and D4 due to Fe³⁺ (δ ≈ 0.46 mm s⁻¹, ΔE_Q ≈ 0.48 and 0.97 mm s⁻¹, respectively). Microprobe Raman spectra obtained with a laser at 514.53 nm show the characteristic bands of synthetic green rusts at 427 and 518 cm⁻¹. X-ray absorption spectroscopy shows that Mg is present in the mineral in addition to Fe, that the space group is and the lattice parameter a ≈ 0.30–0.32 nm. The mineral forms by partial oxidation and hydrolysis of aqueous Fe²⁺, to give small crystals (400–500 nm) in the form of hexagonal plates. The mineral is unstable in air and transforms to lepidocrocite or goethite. The name is for the locality of the occurrence, a forested Gleysol near Fougères, Brittany, France. Its characteristic blue-green color (5BG6/1 in the Munsell system) has long been used as a universal criterion in soil classification to identify Gleysols. From a thermodynamic model of soil-solution equilibria, it was proposed that for the eponymous mineral, Fougères-fougerite, OH⁻ may be the interlayer anion. In other environments, the interlayer anion may be different, and other varieties of fougerite may exist. Fougerite plays a key role in the pathways of formation of Fe oxides.

Recycling organic waste products in agriculture is a potential route for the dispersion of pharmaceutical residues in the environment. In this study, the concentrations of thirteen pharmaceuticals and the personal care product triclosan (PPCPs) were determined in different environmental matrices from long-term experimental fields amended with different organic waste products (OWPs), including sludge, composted sludge with green wastes, livestock effluents and composted urban wastes applied at usual agricultural rates. PPCP concentrations were different in OWPs, varying from a few micrograms to milligrams per kilogram dry matter or per litre for slurry. OWPs from sludge or livestock effluents primarily contained antibiotics, whereas composted urban wastes primarily contained anti-inflammatory compounds. PPCP contents in soils amended for several years were less than a few micrograms per kilogram. The most persistent compounds (fluoroquinolones, carbamazepine) were quantified or detected in soils amended with sludge or composted sludge. In soils amended with composted municipal solid waste, carbamazepine was quantified, and fluoroquinolones, ibuprofen and diclofenac were sometimes detected. The small increases in fluoroquinolones and carbamazepine in soils after individual OWP applications were consistent with the fluxes from the applied OWP. The measured concentrations of pharmaceuticals in soil after several successive OWP applications were lower than the predicted concentrations because of degradation, strong sorption to soil constituents and/or leaching. Dissipation half-lives (DT50) were approximately 750-2500, 900 and <300days for fluoroquinolones, carbamazepine and ibuprofen, respectively, in temperate soils and <350 and <80days for fluoroquinolones and doxycycline, respectively, in tropical soils. Detection frequencies in soil leachates were very low (below 7%), and concentrations ranged from the limits of detection (0.002-0.03μg/L) and exceptionally to 0.27μg/L. The most frequently detected pharmaceuticals were carbamazepine and ibuprofen. Based on the risk quotient, the estimated ecotoxicological risks for different soil organisms were low.