The Interaction between Hg and N on Ex-gold Mining Soil

Although green manure rotation is often used to promote soil fertility and crop yield, the effects of this management practice on the nitrogen or phosphorus balance and the relationship between nutrient balance and the increase in soil nutrients have not been systematically studied. We investigated the apparent nitrogen and phosphorus balances and their associations with soil nitrogen and phosphorus increases, respectively, in a 34-year-old experimental site with various green manures and rice rotations using linear and logistic models. Cropping treatments included a rice-rice-winter fallow treatment as a control (RRW) and three green manure rotation treatments: rice-rice-ryegrass (RRR), rice-rice-oil rape (RRO), and rice-rice-Chinese milk vetch (RRC). We found that apparent nitrogen and phosphorus balances of RRR, RRO, and RRC were 164, 162, and 149 kg hm−2, which were all significantly lower than 200 kg hm−2 of RRW (P < 0.05). Moreover, the optimal fitted model of the relationship between cumulative nutrient balance and the increase in soil nutrients was different among treatments. Specifically, the correlation coefficients of cumulative nitrogen balance and soil nitrogen increase of RRR, RRO, and RRC in the linear model (0.49, 0.80, and 0.63) were all significantly lower than in the logistic model (0.81, 0.90, and 0.82). The correlation coefficients of cumulative phosphorus balance and increase in soil phosphorus of RRW in the linear model (0.81) were significantly lower than in the logistic model (0.91). Parameter analysis of the optimal fitted model revealed that RRC would increase the storage capacity of soil nitrogen and decrease the rate of soil phosphorus accumulation. Our results suggested that long-term rice-rice-green manure rotation could significantly change the apparent nitrogen and phosphorus balance and their association with soil nitrogen and phosphorus content, respectively. Our study highlights the importance of green manure rotation in an agro-ecological environment and soil fertility in a double rice cropping system in red paddy soil.

Potassium (K) is among the essential macronutrients needed for plant growth and it’s also an extremely dynamic ion in both soil and plant systems. K+ moves intensely in a plant system but moderately in a soil system. The average soil deposits of K generally are plentiful, but their mainstreams are not readily available for crop uptake. Many researches have dealt with the response of crops to potassium application, but few literatures have tackled that of maize to available K and its uptake. This review seeks to discuss current progress concerning the relevance of K in maize crop production and its uptake; how this physiological action transforms into growth and yield. We have reviewed available studies on the content, roles of K in the soil-plant system and factors contributing to K uptake and transportation in plant. Also, the benefits of Potassium Solubilizing Microorganisms (KSMs) as an alternative or in combination with exchangeable K+ are reviewed. Furthermore, K deficiencies in maize causing constraint in physiological activities and rendering weak resistance to pests are also discussed. The current study indicates that intensive agricultural production has led to K nutrient limitation in organic or coarse-textured soil resulting in the reduction of available K reserves. However, an optimal application of K can prevent these fertilization imbalances, which will eventually increase soil fertility.

&amp;lt;p&amp;gt;The Grain for Green Project is one of the important projects implemented by the Chinese government to control soil erosion on the Loess Plateau, and its successful implementation has brought remarkable ecological benefits to relevant regions in China. The land use change is the most intuitive representation. Meanwhile, the soil erosion and soil nutrient distribution has also been influenced to produce significant changes. In this research, the characteristics of soil erosion and nutrient loss characteristics of soils from different land utilization types including apple, shrub, forest, grass and gully land, and their relationship were quantitative evaluated with &amp;lt;sup&amp;gt;137&amp;lt;/sup&amp;gt;Cs tracer technique in a typical watershed, which is located in Yan'an city of northern Shaanxi province in China. Results showed that soil erosion was observed in the all-land use types but shrub land, however, the degree of soil erosion was slight (the maximum value of soil erosion rate for 151.27 t/km&amp;amp;#178;&amp;amp;#8226;a). The soil erosion of forest was significant differences with apple, shrub and gully but not with grassland. As will as there were significant differences in among shrub, apple orchard and gully. The soil nutrient loss, soil nutrient status and soil erosion degree showed a very similar pattern of spatial variation, with the difference that the correlation coefficients were different. In addition, there was highly signi&amp;amp;#64257;cantly positive correlation between three indicators. However, Soil total nitrogen, total phosphorus, organic matter, N/P and C/P significantly affected the total nitrogen loss, total phosphorus loss and organic matter loss, but C/N ratio and nutrient loss were not significant. Soil nutrient loss in small watershed was more closely related to the soil carbon and nitrogen and soil erosion. The basic contents of different nutrients affected their nutrients loss laws, by and large, soil erosion affected soil nutrient loss and results in differences in nutrient distribution in the small watershed.&amp;amp;#160;&amp;lt;/p&amp;gt;

Land use patterns and vegetation coverage in semi-arid areas of the Loess Plateau have undergone great changes due to the implementation of the “Grain for Green” project. The introduction of legume pasture species, such as alfalfa (Medicago sativa L.) and sweet clover (Melilotus officinalis L.), is one of the most efficient methods of vegetation restoration and reconstruction in this region. However, there is a need for an effective assessment of the root system distribution and its interaction with soil after long-term introduction. An experiment involving the introduction of alfalfa and sweet clover on abandoned farmlands was initiated in 2003 to assess the long-term effects. After 17 years, root and soil samples at depths of 0–20 and 20–60 cm were collected to characterize the root biomass, root carbon (C), nitrogen (N), and phosphorus (P), soil microbial biomass carbon (MBC) and nitrogen (MBN), soil organic carbon (SOC), and soil N and P. The results showed that the root biomass density of alfalfa in the 0–20 and 20–60 cm layers (63.72 and 12.27 kg m–3, respectively) were significantly higher than for sweet clover (37.43 and 8.97 kg m–3, respectively) and under natural abandonment (38.92 and 9.73 kg m–3, respectively). The SOC, total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), nitrate-nitrogen (NO3–-N), MBC and MBN in the 0–20 and 20–60 cm layers were higher after alfalfa introduction compared with sweet clover introduction and natural abandonment, although the ammonia-nitrogen (NH4+-N) concentration in the 0–20 cm layer was lower. There were significantly positive correlations between root biomass density and both soil nutrients and microbial biomass, while there was a negative correlation between the soil NH4+-N and root biomass density. These results indicate that alfalfa root growth improved soil organic matter accumulation and nutrient mineralization. The accumulation and mineralization of soil nutrients also guaranteed root and microorganism growth. Therefore, it was concluded that alfalfa introduction will promote soil nutrients immobilization and mineralization and may enable sustainable land use in the semi-arid region of the Loess Plateau, China.

Radon diffusion through thin plastics

The soil nutrient status in riparian zones, which are transitional areas between aquatic and terrestrial ecosystems, is highly dynamic and plays a crucial role in the health of aquatic ecosystems. However, the mechanisms underlying nutrient changes in these zones remain unclear and vary across studies. This study employed spatial distribution analysis, linear regression, Pearson's correlation, redundancy analysis (RDA), random forest analysis and partial least squares path modelling analysis (PLS–PM) to investigate the horizontal and vertical variations in soil nitrogen and phosphorus, as well as the regulatory roles of topography, hydrology and plants in soil nutrient changes in the riparian zones of Dongjiang Lake. The results showed clear stratification of soil nutrients, with nitrogen and phosphorus concentrations in the 0–20‐cm soil layer generally higher than those in the 20–40‐cm soil layer. Random forest analysis indicated that the key factors influencing nitrogen were flooding duration, flooding height and the digital elevation model (DEM), while phosphorus was mainly affected by plant factors (Shannon–Wiener index, Simpson index, density, coverage and biomass), distance from the mountain to plots, DEM and flooding duration. PLS–PM analysis revealed that soil nitrogen and phosphorus were shaped not only by the direct effects of topography, hydrology and plants but also by the indirect effects of hydrology mediated by topography. Furthermore, soil nitrogen in riparian zones was co‐regulated by plant and hydrological factors, whereas soil phosphorus was co‐regulated by topographic and plant factors. Compared with nitrogen, phosphorus exhibited greater instability. This mechanistic understanding of soil nutrient dynamics provides a scientific basis for nutrient control, management and ecological restoration in riparian zones.

Newly formed polyploids face strong barriers preventing their establishment, but despite these barriers polyploidy is prevalent among angiosperms being a major mechanism of adaptation and speciation. Morphological and phenological differences between diploids and related polyploids often results in different ecological tolerances among cytotypes. Differences in competitive abilities brought on by genome duplication can vary with abiotic and biotic environmental conditions and influence polyploid establishment. In my theses, I test the overall hypothesis that soil nutrient availability and polyploidy interact to affect competition and performance of Fireweed plants (Chamerion angustifolium), which differ in ploidy levels. Additionally, I examined whether insect feeding damage is influenced by soil nutrient availability and polyploidy. In the first chapter, I detail a greenhouse experiment, in which I tested how soil nitrogen and ploidy level interact to affect plant competitive outcomes and performance of diploid and autotetraploid plants (cytotypes). To do this, in a greenhouse experiment, I grew cytotypes alone or with another plant of either the same or a different cytotype under low and high soil nitrogen conditions. To examine whether herbivory may affect competitive outcomes, and if soil nitrogen supply and/or ploidy level influenced insect feeding damage, we conducted a leaf-choice insect bioassay and a whole-plant insect bioassay. I found that a competitor’s ploidy level influenced plant growth traits as plants grown with tetraploids were generally smaller, but soil nitrogen availability did not differentially affect this competitive outcome. Additionally, insect damage was not influenced by competition nor soil nitrogen supplies. The second chapter details a greenhouse experiment where I examined how nitrogen and phosphorus availability and ploidy level interact to affect plant competitive outcomes and the performance of diploid, established tetraploid, and neotetraploid cytotypes. I grew the plants alone or in competition with the same or a different cytotype under low and high soil nutrient concentrations. I also conducted a leaf-choice insect bioassay and a whole-plant insect bioassay to test if competitive outcomes were affected by herbivory, and if a plant’s ploidy level and soil nutrient supplies influenced insect feeding damage. We found that whole genome duplication effects competitive outcomes and plant-herbivore interactions, but these outcomes vary depending on nutrient supply. Overall, our findings suggest that polyploids possess some traits related to competitive ability, and that these traits may have been selected for in natural populations. We conclude that soil nutrient availability plays a role in mediating the competitive outcomes between cytotypes and could be

Mine dumps are man-made geological formations characterized by unique chemical, particle-size, bacterial, and physical and mechanical features, representing deposits or cumuli of crushed, grounded and roasted material. Processing plants of metallic poli-sulfide ore deposits have contributed to pollute soils and surface and ground waters in many areas worldwide. The southern sector of the Apuan Alps (northern Tuscany, Italy) hosts a number of small pyrite &amp;#177; barite &amp;#177; iron-oxide orebodies that have been exploited since at least the Middle Age, whose activity ceased at the end of the 20th century. The most important mining areas were those distributed along a 10 km-long NE-SW strip in high Hg contents the southern portion of the Apuan Alps. In this framework, the Rezzaio treatment plant (Valdicastello Carducci, Pietrasanta), dismissed since 1991, was the site where ore bodies hosted within the metamorphic rocks of the Apuane Unit, mainly from Monte Arsiccio, Pollone and Buca della Vena mines were treated. The materials extracted from these mines were barite and iron oxides (both hematite and magnetite) used as weighting agents as drilling mud during petroleum drilling wells. Abandoned mining tunnels and dumps and plants for mineral treatment are still present in the area, posing a series of environmental threats. Our study focused on assessing the impact due to mercury contamination released by the treatment plant of Rezzaio by the past-mining activity. The aims of this study were to (1) determine the concentration of Gaseous Elemental Mercury (GEM or Hg0) in air and interstitial soil inside and outside the plant, including the working areas and the edifices where the workers were operating (e.g., offices, laboratory, rock storage); (2) assess the total amount of Hg in the top- and sub-soils, mostly developed on a small mining dump and (3) quantify the release of Hg by soil leaching tests by Milli-Q water. According to WHO and the Italian Legislative Decrees, the GEM values in air and outside the plant and in the plant edifices and mining structure are below the Recommended Exposure Limit. The spatial distribution of Hg indicates that up to 88 mg/kg were recorded in the top- and sub-soils, the highest contents being found on the small mining dump that is partly the bank of a creek. However, in most cases the concentration of Hg leachate were &lt; 1&amp;#181;g/L, suggesting that mercury is likely trapped within crystalline silicate structures recalcitrant to chemical weathering. These results suggest that despite the high contents, mercury is not apparently playing a critical role as a contaminant in the Rezzaio area, being hosted in relatively insoluble minerals.

The objective of this research project is to define the occurrence, transport, and fate of mercury in air, water, and soil at natural gas production sites that had been instrumented with mercury-based gas flowmeters in the past. The primary focus of this research was initially on determining the potential for mercury contamination in groundwater at these sites. The scope was later broadened to include determinations of the spatial distribution of mercury in soil. Air concentrations were determined solely as a health and safety routine.

The production of organic agriculture products has become one of the most growing areas of economic activity, with projected annual growth of 10-12%. At the same time, the demand for organic products significantly exceeds the supply, which is largely due to the lack of land that can be allocated for this production. Russia, which has significant areas of virtually unused land on which mineral fertilizers and pesticides have not been used for a long time, reaching 19.7 million. ha, has a significant potential for development in this direction. At the same time, considering that a significant part of unused territories is located within the zone of risky agriculture, and also has soils with a low level of natural fertility, degraded, arid, waterlogged, etc., the actual amount of land resources that can be involved in organic agriculture is significantly less. For the most complete introduction into circulation of unused agricultural lands, it is necessary to increase the knowledge intensity and manufacturability of organic agriculture, for which research work in the following areas is highly relevant: 1) optimization of the balance of humus and nutrients in soils, 2) breeding and seed production of crops for organic agriculture, 3) development of biological products for disease and pest control, 4) development of optimal farming systems taking into account local soil and climatic conditions, 5) optimization of agricultural landscapes based on increasing the diversity of agricultural land use. Along with the involvement of unused lands in the organic production system, the development of the industry largely depends on the system of training qualified personnel in this area, which should take into account the specifics of the technologies used, which differ significantly from traditional farming systems. To do this, it is necessary to update existing professional standards, which should include generalized labor functions related to the development and implementation of organic farming technologies, as well as knowledge and skills in organizing organic production. On the basis of updated professional standards, universities should form new professional competencies and a corresponding set of academic disciplines. The personnel training system for the industry should include various levels of training: agricultural classes, higher education, additional professional education.

Soil carbon, nitrogen and phosphorus concentrations were determined and the soil structure evaluated for four annual courses in a rotation (Year 1, fattening, non-nose-ringed pigs at a stocking density of one pig produced per 150–200 m2 depending on seasonal conditions; Years 2 and 3, spring wheat; Year 4, reseeded grass-clover) for organically accredited pig production on a shallow calcareous soil in southwest England. Soil nitrogen and phosphorus concentrations and organic decomposition rates were highest when pigs were present, consistent with recent inputs of feed and nutrient redistributed in dung and urine. Soil nitrogen and phosphorus concentrations and organic decomposition rates declined over the subsequent courses. The overall production system was sustained by inputs of pig feed one year in four, with nutrients being carried over to subsequent years. The pigs caused significant physical damage leading to soil disaggregation, but the soil structure recovered over the following 2 years. The high concentrations of inorganic nitrogen, particularly nitrate at high concentration ‘hot-spots’ around feeders and housings, and the poor soil structure caused by the pigs represented a significant risk of loss of nutrients and soil. At this site, vertical movement of disaggregated soil and nutrients through cracks and fissures in the underlying limestone may have been an additional route of loss alongside denitrification, volatilisation, erosion and run-off.

The aim of this study was to determine the effect of a Douglas fir plantation along a stand chronosequence in the North Apennine (Italy) on soil carbon and nitrogen stocks, as well as on soil chemical and biochemical properties involved in the nutrients biogeochemical cycle. In 2014, three sites of Douglas fir stands, aged 80, 100, and 120 years, were selected in Vallombrosa forest to study the dynamics of soil nutrients in the ecosystem. Along the Douglas fir chronosequence, general evidence of surface element accumulation was found, including a conspicuous increase of alkaline element with respect to Al, which was attributed to the increase of soil pH along the Douglas fir stand age classes. A general increase of specific enzyme activity (per unit of organic carbon) and functional diversity were observed in the epipedon of the Douglas fir stand over 100 years of age. Moreover, the (chitinase + leucine aminopeptidase) to acid phosphatase ratio progressively increased from 0.15 to 0.31 in the epipedon of the chrononsequence, while the β-glucosidase to (chitinase + leucine aminopeptidase) ratio decreased from 1.45 to 0.83, suggesting nitrogen limitation with respect to carbon. In fact, the soil carbon stock progressively increased along the chronosequence, in the epipedon from 17 to 53 Mg C ha−1 and in the endopedon from 17 to 37 Mg C ha−1. Conversely, the soil nitrogen stock increased from 1.2 to 2.4 Mg N ha−1, but not over the 100-year-old stand class. In conclusion, soil organic matter accumulation became sufficient to define the umbric horizon in the Northern Apennines when the Douglas fir plantation reached the age of 100 years. Over this age class of plants, a limitation of soil nitrogen may occur, affecting enzyme activities regulating the biogeochemical cycle of nutrients.

Atmospheric nitrogen deposition has a profound impact on soil nitrogen (N) cycling within terrestrial ecosystems, altering the microbial community structure and composition. To investigate how nitrogen deposition impacts microbial communities across different seasons, this study focused on a mature subtropical Quercus aquifolioides forest. Four nitrogen treatments were applied, and high-throughput sequencing was utilized to analyze soil microbial composition and structure changes during dry and wet seasons. Additionally, the study explored the interactions between soil nutrients, microbial communities, and nitrogen treatments. Following four years of nitrogen supplementation, the results revealed that: (1) Soil chemistry and enzyme activity shifted significantly due to the combined effects of nitrogen addition and seasonal variations. A marked reduction in soil pH indicated substantial acidification, although the wet season’s increased soil moisture mitigated these effects. (2) Fungal richness and diversity were more sensitive to nitrogen addition than bacterial diversity. (3) During the wet season, nitrogen deposition caused notable shifts in soil microbial community composition, with a notable elevation in the relative proportion of the fungal genus Sebacina (↑112.68%) under MN treatment. (4) Nitrogen addition affected the co-occurrence network complexity of soil bacteria and fungi in a season-dependent manner. During the dry season, bacterial network complexity decreased significantly while fungal network complexity increased. In contrast, the wet season showed an elevation in bacterial network complexity and a reduction in fungal network complexity. (5) The fungal community structure remained stable across seasons and nitrogen treatments, whereas the bacterial community structure showed significant differences after nitrogen addition. Environmental factors influencing bacterial and fungal community structures varied depending on water conditions. These findings provide insights into forest soil management and microbial remediation strategies in response to future atmospheric nitrogen deposition.

One of the hazardous wastes generated from unlicensed gold mining is mercury. Mercury is a toxic metal that can have a negative impact on the environment such as reducing soil and water quality and disturbing human health. The presence of mercury in the soil is completely controlled by adsorption-desorption of various sorbents. Soil properties greatly affect the adsorption and desorption of mercury in the soil. Because different soil properties will adsorb and desorb mercury in different ways and amounts. The purpose of writing this article is to review the results of previous research on the adsorption-desorption of mercury in soil so as to determine the extent of the risk of soil and environmental pollution. The method used in this writing is to collect and process data sources from previous research published in scientific articles, books, and discussion results. The results show that soils with high organic matter, iron oxide and clay content can absorb more Hg2+. In addition, lower pH has more hydroxylated surfaces that can adsorb more Hg2+. Irreversibility was found where the amount released or desorbed was less than the adsorption of mercury.

Tempe is the most popular traditional fermented food in Indonesia that has high nutritional values such as high protein content high fatty acid content, vitamin B12, excellent digestibility, and good antioxidant content sources. Tempe also has low in anti-nutrition factors such as phytic acid, oligosaccharides. The purpose of this study is to compare traditional Tempe produced from West Sumatra, Indonesia, which is comparing the yellow and black soybeans, with a focus on antioxidant capacity. Six samples of Tempe were collected in Padang and Padang Panjang, Indonesia. Microorganism isolated from tempe samples were identified and the antioxidant capacity was determined using different antioxidant capacity assays, then Vitamin B12 determination in mocrobiological assay was perfomed. The result is included the mean of antioxidant of black soybeans = 0.008333 with a standard deviation of 0.0006429 and the mean of antioxidant of yellow soybeans = 0.008767 with a standard deviation of 0.0027465. In conclusion, it can be seen that the F count for antioxidants is 8647 with a probability of 0.042. Because of the probability value is &lt; 0.05, then H0 is rejected or the two population variances are different (heterogeneous).