Main soil contaminants and their fate in the soil environment

Soil pollution is invisible to the human eye, but it compromises the quality of the food we eat, the water we drink, and the air we breathe and puts human and environmental health at risk. Most contaminants originate from human activities such as industrial processes and mining, poor waste management, unsustainable farming practices, accidents ranging from small chemical spills to accidents at nuclear power plants, and the many effects of armed conflicts. Pollution knows no borders: contaminants are spread throughout terrestrial and aquatic ecosystems and many are distributed globally by atmospheric transport. In addition, they are redistributed through the global economy by way of food and production chains. 
 
 Soil pollution has been internationally recognized as a major threat to soil health, and it affects the soil’s ability to provide ecosystem services, including the production of safe and sufficient food, compromising global food security. Soil pollution hinders the achievement of many of the United Nations Sustainable Development Goals (SDGs), including those related to poverty elimination (SDG 1), zero hunger (SDG 2), and good health and well-being (SDG 3). Soil pollution hits the most vulnerable hardest, especially children and women (SDG 5). The supply of safe drinking water is threatened by the leaching of contaminants into groundwater and runoff (SDG 6). CO2 and N2O emissions from unsustainably managed soils accelerate climate change (SDG 13). Soil pollution contributes to land degradation and loss of terrestrial (SDG 15) and aquatic (SDG 14) biodiversity, and decreased the security and resilience of cities (SDG 11), among others

Subdiffraction, Luminescence-Depletion Imaging of Isolated, Giant, CdSe/CdS Nanocrystal Quantum Dots

Subdiffraction spatial resolution luminescence depletion imaging was performed with giant CdSe/14CdS nanocrystal quantum dots (g-NQDs) dispersed on a glass slide. Luminescence depletion imaging used a Gaussian shaped excitation laser pulse overlapped with a depletion pulse, shaped into a doughnut profile, with zero intensity in the center. Luminescence from a subdiffraction volume is collected from the central portion of the excitation spot, where no depletion takes place. Up to 92% depletion of the luminescence signal was achieved. An average full width at half-maximum of 40 ± 10 nm was measured in the lateral direction for isolated g-NQDs at an air interface using luminescence depletion imaging, whereas the average full width at half-maximum was 450 ± 90 nm using diffraction-limited, confocal luminescence imaging. Time-gating of the luminescence depletion data was required to achieve the stated spatial resolution. No observable photobleaching of the g-NQDs was present in the measurements, which allowed imaging with a dwell time of 250 ms per pixel to obtain images with a high signal-to-noise ratio. The mechanism for luminescence depletion is likely stimulated emission, stimulated absorption, or a combination of the two. The g-NQDs fulfill a need for versatile, photostable tags for subdiffraction imaging schemes where high laser powers or long exposure times are used

Point-contact spectra of the heavy-fermion superconductors U Be

We have measured the current-voltage characteristics of point contacts between UBe13 or UPt3 and the normal metals W or Pt (metallic point contacts) or GaAs (Schottky-barrier tunneling contact) in the temperature range between 50 mK and 1 K. In the metal-point-contact characteristics (dVdI vs V) there appear zero-bias minima of width 2 below Tc. The ratio 2 kBTc is close to the BCS value. The tunneling spectra of UPt3 exhibit weak additional structure below Tc. A value 2 has been estimated, which is a factor of 2 larger than that for the metal point contacts. © 1987 The American Physical Society

Comparative study of dioxin contamination from forest soil samples (BZE II) by mass spectrometry and EROD bioassay.

Dioxins and dioxin-like compounds can be analyzed by bioanalytical screening methods to evaluate their biotoxicity. In vitro bioassays, based on 7-ethoxyresorufin-O-deethylase (EROD) and the activity of cytochrome P450 1A1 and the aryl hydrogen receptor (AhR) pathway, are employed for the evaluation of bioanalytical equivalents (BEQ) of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) from a wide variety of sample matrices. Here, we present the evaluation of 11 humic soil samples derived from forest stands across Germany and a comparison of the BEQ values against toxic equivalents (TEQ, PCDD/Fs+PCBs) derived by chemical analysis. BEQ values ranged from 8.8 to 34.1 while TEQ values from 13.9 to 60.5 pg/g dry weight. Additional two subsequent mineral layers were analyzed to identify the BEQ/TEQ gradient vertically, showing a TEQ decrease of 85.1 and 93.8 % from the humic to the first and second mineral layers, respectively. For BEQ values, a decrease as well as an increase was detected. BEQ measurements were performed with and without sample clean-up. Omitting clean-up revealed about 20 times increased BEQ values presumably due to non-persistent bioactive compounds not detected by chemical analysis. The results we present suggest that the EROD assay can be used for the screening of large sample quantities for the identification of samples showing dioxin and dioxin-like contaminations even at low levels, which can then be further analyzed by chemical analysis to identify the congener composition. The study also shows that EROD results give a qualitative image of the contamination. EROD seems to be interfered with cross-contaminants specifically for soils with high biological activity as forest layers

Certification of the European Reference Soil Set (IRMM-443 - EUROSOILS). Part 1: Adsorption Coefficients for Atrazine, 2.4-D and Lindane.

Abstract not availableJRC.D-Institute for Reference Materials and Measurements (Geel