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Organic dyes have been turned into an important emerging type of chemical pollutants with the development of rural textiles, synthetic dye, printing, and dyeing industries and the continuous release from washing fabrics and clothes in recent decades. In order to assess ecological risk of reactive X-3B red dye as a typical dye, the adsorptive and desorptive traits of the dye in soils were investigated and the environmental factors influencing those processes were examined and discussed. Adsorptive and desorptive isotherms and dynamics of reactive X-3B red dye as a typical emerging pollutant were investigated by the standard batch experiments using four typical soils in China including relatively clean brown earth (burozem), drab soil (cinnamon soil), paddy soil (aquorizem), and red soil (krasnozem) and calculated by mathematical models using the Microsoft Excel software. It was suggested that the adsorptive behavior of reactive X-3B red dye by the four soils can basically be described using the Langmuir equation, and their maximum adsorbing capacity was in the sequence paddy soil > red soil > brown earth > drab soil. The adsorption could be divided into four stages including high-speed adsorption, slowdown adsorption, tardiness adsorption, and zero-approaching adsorption. It was also indicated that the adsorption ability of the dye decreased with the reduction in soil organic matter or air temperature and under neutral, runny, or unwatered conditions. The increase of desorption was observed with the decrease of soil organic matter and the increase of air temperature or soil moisture, while desorption was inhibited by the acidification or basification of soils. The comparative study validated that the basic adsorption–desorption laws of the dye at high concentrations were basically consistent with those at low concentrations. It could be concluded that reactive X-3B red dye has the potential properties of persistent organic pollutants with high ecological risk, and its release from contaminated soils and uptake by crops can be disturbed and changed by human activities.

With land application of farm effluents from cows during housing or milking as an accepted practice, there are increasing concerns over its effect on nitrogen (N) loss through ammonia (NH3) volatilization. Understanding the relative extent and seasonal variation of NH3 volatilization from dairy effluent is important for the development of management practices for reducing NH3 losses. The objectives of this study were to determine potential NH3 losses from application of different types of dairy effluent (including both liquid farm dairy effluent (FDE) and semi-solid dairy farm manure) to a pasture soil during several contrasting seasons and to evaluate the potential of the urease inhibitor (UI)—N-(n-butyl) thiophosphoric triamide (NBTPT, commercially named Agrotain®) to reduce gaseous NH3 losses. Field plot trials were conducted in New Zealand on an established grazed pasture consisting of a mixed perennial ryegrass (Lolium perenne L.)/white clover (Trifolium repens L.) sward. An enclosure method, with continuous air flow, was used to compare the effects of treatments on potential NH3 volatilization losses from plots on a free-draining volcanic parent material soil which received either 0 (control) or 100 kg N ha−1 as FDE or manure (about 2 and 15 % of dry matter (DM) contents in FDE or manure, respectively) with or without NBTPT (0.25 g NBTPT kg−1 effluent N). The experiment was conducted in the spring of 2012 and summer and autumn of 2013. Results showed that application of manure and FDE, both in fresh and stored forms, potentially led to NH3 volatilization, ranging from 0.6 to 19 % of applied N. Difference in NH3 losses depended on the season and effluent type. Higher NH3 volatilization was observed from both fresh and stored manure, compared to fresh and stored FDE. The difference was mainly due to solid contents. The losses of NH3 were closely related to NH4 +-N content in the two types of manure. However, there was no relationship between NH3 losses and NH4 +-N content in either type of FDE. There was no consistent seasonal pattern, although lower NH3 losses from fresh FDE and stored FDE applied in spring compared to summer were observed. Potential NH3 losses from application of fresh FDE or manure were significantly (P < 0.05) reduced by 27 to 58 % when NBTPT was added, but the UI did not significantly reduce potential NH3 volatilization from stored FDE or manure. This study demonstrated that NH3 losses from application of FDE were lower than from manure and that UIs can be effective in mitigating NH3 emissions from land application of fresh FDE and manure. Additionally, reducing the application of FDE in summer can also potentially reduce NH3 volatilization from pasture soil.

Implementation of green roofs could help to reduce rapid runoff and help cities to mitigate heat islands. The aim of the study is to assess the water and temperature regimes of four experimental green roof test beds having different growing media and plant coverage during the vegetation season 2018. Experiments were conducted in four test beds (1 × 1 m) established on a flat roof. Two types of growing media were used. The first (A) was a substrate composed of crushed spongolite, crushed expanded clay, and peat. The second (B) was a coarser substrate, composed of crushed expanded clay, crushed bricks, peat, and compost. Two test beds, hereafter designated ACu and BCu, were filled with substrates A and B respectively and planted with a mixture of Sedum spp. cuttings with approximately 10% coverage. The substrate thickness was 6 cm. Two other test beds, designated ACa and BCa, were filled to a depth of 4 cm with A and B growing media, respectively, and planted with a carpet of Sedum spp. with approximate coverage of 100%. The experiment was conducted over one growing season. Continuous monitoring of substrate temperature, water content, and outflow was conducted on each test bed. The lowest runoff coefficient was observed in test bed ACu, while the highest runoff occurred in test bed BCu, with twice the amount of outflow as ACu. The total runoff coefficient of ACa was more than one-third higher than that of ACu. The lowest maximum substrate temperature on the hottest day of the season was observed in bed ACa with a temperature of 40.6 °C, while the highest temperature was seen in bed BCu, 7.9 °C higher. The analysis of the rainfall-runoff relationship calculated for individual rainfall events demonstrated that runoff coefficients depended on initial water content, rainfall intensity, rainfall depth, substrate type, and vegetation cover. Beds planted with sedum carpets and having more extensive vegetation coverage were superior at moderating extremes of temperature.

Under rapid climate change, soil organic carbon (SOC) dynamic in frozen ground may significantly influence terrestrial carbon cycles. The aim of this study was to investigate the storage, spatial patterns, and influencing factors of SOC in frozen ground on the Qinghai-Tibet Plateau, which known as the earth’s Third Pole. Using the observed edaphic data from China’s Second National Soil Survey, we estimated the SOC storage (SOCS) of frozen ground (including permafrost, seasonally, and short time frozen ground) on the plateau with a depth of 0–3 m. Furthermore, the effect of vegetation and climate factors on spatial variance of SOC density (SOCD) was analyzed. The SOCD decreased from the southeastern to the northwestern part of the plateau, and increased with shorten of freezing duration. SOCS of permafrost, seasonally, and short time frozen ground were calculated as 40.9 (34.2–47.6), 26.7 (24.1–29.4), and 6 (5.6–6.4) Pg, making a total of 73.6 (63.9–83.3) Pg in 0–3 m depth on the plateau. Normalized difference vegetation index and mean annual precipitation could significantly affect the spatial distribution of SOC in permafrost and seasonally frozen ground. The soil in plateau frozen ground contained substantial organic carbon, which could be affected by plant and climate variables. However, the heterogeneous landform may make the fate of carbon more complicated in the future.

This study investigated the C and N mineralisation potential of solid fractions (SFs) from co-digestated pig manure after P-stripping (P-POOR SF) in comparison with P-rich SFs, as a means to estimate their organic matter stability in soil. Compost (COMP) and biochar (BCHR) (made from P-POOR SF) were also included in the study as reference biosolids. The SFs were incubated in a sandy-loam soil under moist conditions to determine production of CO2 and mineral N. At specified intervals, CO2 evolution in the mixtures was measured via the alkali trap method and titration over a period of 81 days, while mineral N was measured using a flow analyser after KCl extraction over a period of 112 days. The various SFs showed similar patterns of C mineralisation (15–26% of added total C in 81 days) that were clearly higher than for COMP and BCHR (6% and 7%, respectively). Temporary N immobilisation was observed in biosolids with a high C/N ratio. The effective organic matter (EOM) of the SFs was calculated based on the C mineralisation data and varied between 130 and 369 kg Mg−1. The SF with a reduced P content had a high EOM/P ratio which is beneficial in areas where P status of the soil is already high. Moreover, the N mineralisation patterns confirm that a high C/N ratio may also reduce risks for N leaching due to temporary N immobilisation.

Soil microorganisms and their interactions with environmental factors govern critical ecosystem processes. However, the changes of soil microbial communities (e.g., relative abundance changes of different phylotypes) and the links between specific environmental factors and microbial communities are not well understood. We applied high-throughput sequencing of 16S rRNA gene amplicons to investigate the effects of mineral fertilizers P (superphosphate), N (urea), and NP and organic manure fertilizer (M) and its combined with mineral fertilizers (NM, PM, NPM) on bacterial and archaeal communities in rain-fed winter wheat soils in a 30-year experiment in the Loess Plateau of northwest China. Dramatic changes of soil respiration and the concentrations of total organic C, total N, and microbial biomass C and N were found in manure application soils (M, NM, PM, NPM) and some of them in NP soil. Soil microbial community structure shifted after fertilization, and a significant difference of prokaryotic community structure was found between mineral fertilizer soils (P, N, and NP) and manure application soils (M, NM, PM, NPM) except the soils between PM and P. The prokaryotic community structure in M soil was different from that in NM and NPM soils and differed between N and P and NP soils. Acidobacteria, Actinobacteria, and Proteobacteria were the predominant phyla (55.5–76.5 % of abundance) and, together with some other phyla, were changed by fertilization at the phylum or lower taxon ranks. No fertilizer soil had the highest relative abundances of phyla WS3 and Gemmatimonadetes. P soil changed the relative abundances of phyla Acidobacteria, Gemmatimonadetes, and Verrucomicrobia, but only enriched the bacteria at the family level (Micrococcaceae) when combined with N or M application (NP, PM, and NPM). Some copiotrophic bacteria showed different responses to nitrogen and manure applications, e.g., Actinobacteria increased in abundance in nitrogen application soils (N, NP, NM, and NPM), whereas Bacteroidetes and Gammaproteobacteria increased in abundance in manure application soils (M, NM, PM, and NPM). The above patterns of the relative abundance vs nitrogen or manure application were correlated to soil C and N contents or C/N ratio. These results supported the hypothesis that different bacterial taxa would be favorable in P, N, and manure application soils and suggested that the changes of bacteria taxa in fertilized soils appeared to be more driven by nitrogen and manure applications than P application.

Russian boreal forests represent a globally significant carbon stock, been suffering from frequent surface fires that modify natural cycles of elements, including heavy metal (HM). The behaviour of HM, exerting various ecosystem effects, is not well understood, especially in northern larch forest ecosystems affected by fires. The dynamic of Fe, Pb, Mn, Zn, Cu, Co, Ni and Cr was studied in the 850-day field decomposition experiment in a natural unburned larch stand (Larix gmelinii (Rupr.)) and adjacent burned forest on the Russian Far East. We observed mass loss, HM release/accumulation and correlation of HMs with soil properties. The litter decomposed slower in the burned site, with pronounced differences in the late decomposition stage. The concentrations of HMs except Mn had increased by the end of the experiment in both forest sites. Among all the HMs, Fe, Cr and Ni showed pronounced accumulation in burned stand compare to the unburned forest. Fire does not modify the patterns of HM release/accumulation but significantly alters the final values. In unburned forest, soil pH and water content strongly influenced only Fe dynamics, whereas, on burned site, soil properties correlate with the group of HMs. Our experiment showed that HM dynamics are coupled with the mass loss only in the late stages of litter decomposition. We found that fire’s legacy effect in natural larch forests could last over 15 years, creating favourable conditions for significant accumulation of Fe, Pb, Cr and Ni.

This study aimed to relate the altitudinal and vertical distributions and occurrences of major heavy metals (HMs) to soil physicochemical properties in the riparian soils subject to periodic and intense wet–dry cycles Cadmium (Cd), copper (Cu), and lead (Pb) and their chemical fractions were investigated in the riparian soil (0–40 cm) of the upland and within the water-level-fluctuation zone (WLFZ) at two tributary backwaters of the Three Gorges Reservoir (TGR) in China. Selected soil basic properties and pore structures determining the distribution of HMs and their fractions were identified using correlation and redundancy analysis Cd showed moderate–strong contamination and prevailed in non-residual fraction (>73.2%) in the riparian soil of the tributary backwaters in the TGR. In contrast, Cu and Pb exhibited slight contamination and prevailing in residual fraction (>50.3%). Enrichment of HMs in the lower end relatively flat WLFZ where flow rate decreased abruptly and dramatically was observed. Cd exhibited the largest coefficient of variation (CV, up to 0.263) across soil profiles while Cu showed a relatively homogeneous profile distribution in the riparian soil. Soil organic matter (SOM), cation exchange capacity (CEC), and pH were identified to be the primary factors determining the distributions of Cd, Cu, Pb, and their chemical fractions, respectively, in the riparian soil with a high macroporosity. Nevertheless, soil porosity was the dominant factor (>65.0%) determining the distributions of all the three HMs and their fractions in the non-drainable micropore-dominated riparian soil Soil basic property and pore structure variations due to periodic hydrodynamic disturbances from reservoir operation are closely related to the redistribution of HMs in the riparian soil. The coupling of these two variations is strongly suggested to assist reliable evaluation of various contaminants, including but not limited to HMs, regarding their spatial redistributions and mobilization potentials in the vadose zone at larger scales in response to climate change.