Grevebonner4179

Cement-based solidification/stabilization (S/S) technology is often used to remediate chromium (Cr) contaminated soils. The valence state and mobility of Cr in soils are closely related with redox potential (EH). However, Cr mobilization from the solidified soils influenced by EH has received little attention. In this study, semi-dynamic leaching tests and the toxicity characteristic leaching procedure (TCLP) were performed on a S/S treated Cr contaminated soil under various EH conditions. The effective diffusion coefficient and leachability index were obtained from the leaching data to investigate the leaching behavior of Cr from the S/S treated soil. Speciation of Cr remained in the sample after the leaching process was obtained through the sequential extraction procedures. The results show that an increase in EH increases the effective diffusion coefficient of Cr and, therefore, the amount of Cr leached. This result is attributed to immobile Cr(III) being oxidized to highly mobile Cr(VI). The leachability index results indicate that the cement solidification of Cr contaminated soil may not be appropriate under oxidizing conditions. For the TCLP and sequential extraction procedures, the leached amount of Cr exhibits a strong dependence on EH. As EH increases, the content of Cr remaining in the soil in unstable phases reduced, and more Cr was released to leachant.Straightforward sediment transport is not common in nature and material is storage during transport and reworked by the same processed that lead to initial mass erosion. Despite the development of quantitative assessment by application high accuracy topography measurement, lack of conceptualisation and combination with precise elevation model changes is still missing. This paper presents a field-based channel-bluff connectivity study based on a sediment cascade approach. A TLS (terrestrial laser scanning) time-series database was generated by systematic monitoring of cut-bluff slope surface of the braided-wandering Belá River. The database was used to estimate volume changes and allowed to develop the conceptualisation model of coupling of cut-bluff slope based on spatial and temporal analyses of channel hydrology, gravity conditioned transformation of matter and a detailed of sediment budget calculations. Historical analyses have shown that a flow direction perpendicular to the slope is crucial to activate cut-bluff slope material movement and initiate a sediment cascade, as significant contributors of sediment into the river. Sediment supply to the channels correlates with the magnitude of flood events (maximum discharge, cumulative discharge, cumulative discharge higher than RI1.5, and duration of discharges higher than RI1.5) and lateral migration as a main factor controlling the behaviour of the cut-bluff slope-channel system. During the survey from March 2016 to November 2018, were transported 10,103 m3 (25,964 t) of fine-grained sediment into the river channel.This study investigates the influence of marine habitats (i.e., the intertidal zone, supralittoral zone, and seawater), and polymer types (i.e., polyethylene, PE; polyethylene terephthalate, PET) on the diversity and structure of bacterial communities in marine microplastics. A three-month exposure experiment was conducted in Zhairuoshan Island, Zhoushan, China, a typical caldera volcanic island with minor anthropogenic disturbances. At the end of the exposure period, the transition for peaks corresponding to oxidized groups was observed using micro-Fourier transform infrared spectroscopy. Damages, including pits and cracks, and microorganisms were observed on the surfaces of the PE and PET pellets using scanning electron microscopy. Next-generation amplicon sequencing of the bacterial communities that had colonized the microplastics revealed that bacterial composition significantly varied depending on marine habitats and exposure times, rather than polymer type. Plastic debris in the intertidal zone exhibited the highest bacterial richness and diversity, and Bacillus was considered a potential degrader of plastic debris. The findings demonstrate that bacterial communities that colonize on microplastics are more potentially shaped by marine habitat and exposure time, and this would deepen our understanding of the ecological niche of microplastics surface.The consecutive occurrence of drought and reduction in natural water availability over the past several decades requires searching for alternative water sources for the agriculture sector in California. One alternative source to supplement natural waters is oilfield produced water (OPW) generated from oilfields adjacent to agricultural areas. For over 25 years, OPW has been blended with surface water and used for irrigation in the Cawelo Water District of Kern County, as permitted by California Water Board policy. This study aims to evaluate the potential environmental impact, soil quality, and crop health risks of this policy. We examined a large spectrum of salts, metals, radionuclides (226Ra and 228Ra), and dissolved organic carbon (DOC) in OPW, blended OPW used for irrigation, groundwater, and soils irrigated by the three different water sources. We found that all studied water quality parameters in the blended OPW were below current California irrigation quality guidelines. Yet, soils irrigated by blended OPW showed higher salts and boron relative to soils irrigated by groundwater, implying long-term salts and boron accumulation. We did not, however, find systematic differences in 226Ra and 228Ra activities and DOC in soils irrigated by blended or unblended OPW relative to groundwater-irrigated soils. Based on a comparison of measured parameters, we conclude that the blended low-saline OPW used in the Cawelo Water District of California is of comparable quality to the local groundwater in the region. Nonetheless, the salt and boron soil accumulation can pose long-term risks to soil sodification, groundwater salinization, and plant health; as such, the use of low-saline OPW for irrigation use in California will require continual blending with fresh water and planting of boron-tolerant crops to avoid boron toxicity.The influence of temperature on soil ammonia (NH3) and nitrite (NO2-) oxidation and related NO2- accumulation in soils remain unclear. The soil potential NH3 oxidation (PAO) and NO2- oxidation (PNO) rates were evaluated over a temperature gradient of 5-45 °C in six greenhouse vegetable soils using inhibitors. The values of temperature sensitivity traits such as temperature minimum (Tmin), temperature optimum (Topt), and maximum absolute temperature sensitivity (Tm_sens) were also fitted to the square root growth (SQRT) and macromolecular rate theory (MMRT) models. The ammonia-oxidizing archaea (AOA) and bacteria (AOB) were determined by quantifying amoA, and nitrite-oxidizing bacteria (NOB) were determined by quantifying the nxrA and nxrB. Both models identified that Topt for PAO (34.0 °C) was significantly greater than that for PNO (26.0 °C). The Tm_sens (23.4 ± 2.1 °C) and Tmin (1.0 ± 2.0 °C) for PAO were higher than those for PNO (16.8 ± 3.2 °C and - 11.7 ± 6.7 °C). PAO was positively correlated with AOB-amoA at 20-30 °C and with AOA-amoA at 30-35 °C, while PNO was positively correlated with nxrB at 5-30 °C. Additionally, NO2- and N2O were positively correlated with the (AOA + AOB amoA) to (nxrA + nxrB) ratio, and the concentration of N2O was positively correlated with NO2- accumulation. These results highlight that elevated temperatures resulted in the uncoupling of NH3 oxidation and NO2- oxidation, leading to NO2- accumulation, which could stimulate N2O emissions.The response of soil nitrous oxide (N2O) emission to manure application has been widely reported for laboratory experiments. However, the in-situ effects of manure application on soil N2O emission from field trials (i.e. EMD638683 chemical structure real-world conditions) and related mechanisms are poorly understood at the global scale. Here, we performed a meta-analysis using 262 field observations from 44 publications to assess the in-situ effects of manure application on soil N2O emission and factors regulating N2O emission (e.g., agricultural practices, manure characteristics and initial soil properties). Our analysis found that manure application significantly increased soil N2O emission in field trials. The largest N2O emissions were observed in soils from warm temperate climates, planted with upland non-leguminous crops and using raw manure. Notably, water-filled pore space (WFPS) significantly affected N2O emission; soils with 50-90% WFPS had the highest N2O emissions. Initial soil properties (e.g. pH, texture and organic carbon (C)) were generally not significant for predicting N2O emission, possibly due to changes in soil properties induced by manure additions. Manures with carbon nitrogen ratios (CN) of 10-15 and C contents of 100-300 g C kg-1 produced the lowest N2O emission. The net N2O emission factor (1.13%) resulting from manure application was similar to additions of synthetic N fertilizer (1.25%) and crop residues (1.06%), suggesting that manure application resulted in a similar N2O emission to other soil amendments. Our analysis provides a scientific basis for manure management options to minimize N2O emissions from animal waste disposal on agricultural lands globally.Microplastics (MPs) on lakes have been reported mainly from Europe, Asia, and North America. Then, this study aimed to address the quantification and identification of MPs in nine lakes from the Argentine Patagonian Region. Blue colored fibers were dominant, with a size range between 0.2 and less then 0.4 mm. The mean MPs concentration was 0.9 ± 0.6 MPs m-3, suggesting a low pollution state when compared to other worldwide lakes. Raman microscopy analysis showed a predominance of Indigo Blue Polyethylene terephthalate (PET) particles. The upper-gradient runoff from urban settlements, textiles, and fisheries were identified as the main MPs sources and levels positively correlated with the higher area, shallower depth, and with an end-position in the watershed. These findings fill a gap in the geographical distribution knowledge, setting a baseline that emphasizes the need for better treatment of urban and fisheries wastes in continental lakes.Perfluoroalkyl substances (PFASs) are of particular environmental concern due to their environmental persistence and potential toxicity. Phytoremediation may be used to remove PFASs from wastewater. Here we investigated the uptake mechanism, subcellular distribution, and uptake process of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate acid (PFOS) in the wetland plant Alisma orientale by using a series of hydroponic experiments. Active uptake facilitated by water transporters and anion channels was involved in the uptake of PFASs by plant roots. PFOA and PFOS were mainly distributed in the water-soluble fraction (46.2-70.8%) and in cell walls (45.6-58.4%), respectively. The uptake process was proposed as follows PFOS and PFOA were first distributed in the soluble fraction; a proportion of PFOS and PFOA were adsorbed gradually by the cell wall, and a proportion of PFOS and PFOA in the cell wall passed through the cell wall and plasmalemma and bind with organelles. PFOS and PFOA were transported from the external solution to the vascular bundle of the plant root through both symplastic and apoplastic routes.