Can simultaneous immobilization of arsenic and cadmium in paddy soils be achieved by liming?

Liming acidic paddy soils to near-neutral pH is the most cost-effective strategy to minimize cadmium (Cd) accumulation by rice. However, the liming-induced effect on arsenic (As) (im)mobilization remains controversial and is called upon for further investigation, particularly for the safe utilization of paddy soils co-contaminated with As and Cd. Here, we explored As and Cd dissolution along pH gradients in flooded paddy soils and extracted key factors accounting for their release discrepancy with liming. The minimum As and Cd dissolution occurred concurrently at pH 6.5-7.0 in an acidic paddy soil (LY). In contrast, As release was minimized at pH < 6 in the other two acidic soils (CZ and XX), while the minimum Cd release still appeared at pH 6.5-7.0. Such a discrepancy was determined largely by the relative availability of Fe under overwhelming competition from dissolved organic carbon (DOC). A mole ratio of porewater Fe/DOC at pH 6.5-7.0 is suggested as a key indicator of whether co-immobilization of As and Cd can occur in flooded paddy soils with liming. In general, a high mole ratio of porewater Fe/DOC (≥ 0.23 in LY) at pH 6.5-7.0 can endow co-immobilization of As and Cd, regardless of Fe supplement, whereas such a case is not in the other two soils with lower Fe/DOC mole ratios (0.01-0.03 in CZ and XX). Taking the example of LY, the introduction of ferrihydrite promoted the transformation of metastable As and Cd fractions to more stable ones in the soil during 35 days of flooded incubation, thus meeting a class I soil for safe rice production. This study demonstrates that the porewater Fe/DOC mole ratio can indicate a liming-induced effect on co-(im)mobilization of As and Cd in typical acidic paddy soils, providing new insights into the applicability of liming practice for the paddy soils.

Floating Mat Formation Makes Zizania latifolia More Competitive under the Conditions of Continuous Significant Water Level Rise.

Water level rise is considered an environmental filter for the growth and reproduction of aquatic plants in lakes. Some emergent macrophytes can form floating mats, enabling them to escape from the negative effects of deep water. However, an understanding of which species can be uprooted and form floating mats easily and what factors affect these tendencies remains greatly elusive. We conducted an experiment to determine whether the monodominance of Zizania latifolia in the emergent vegetation community in Lake Erhai was related to its floating mat formation ability and to try to find the reasons for its floating mat formation ability during the continuous increase in water level over the past few decades. Our results showed that both the frequency and biomass proportion of Z. latifolia were greater among the plants on the floating mats. Furthermore, Z. latifolia was more likely to be uprooted than the other three previously dominant emergent species due to its smaller angle between the plant and the horizontal plane, rather than the root:shoot or volume:mass ratios. The dominance of Z. latifolia in the emergent community in Lake Erhai is due to its easier ability to become uprooted, allowing it to outperform other emergent species and become the single dominant emergent species under the environmental filter of deep water. The ability to uproot and form floating mats may be a competitive survival strategy for emergent species under the conditions of continuous significant water level rise.

Arsenic extraction from seriously contaminated paddy soils with ferrihydrite-loaded sand columns.

Reductive dissolution of iron oxides in flooded paddy soils is the most important cause of arsenic (As) release into soil aqueous solution and thus entry into rice. From the perspective of soil cleanup, however, As release under flooded condition could facilitate labile As removal. In this study, a porous column pre-loaded with ferrihydrite (Fh) was constructed, and its efficiency of soil As extraction was investigated using a purpose-designed mesocosm coupled with diffusive gradients in thin films (DGT) for in situ visualization. With Fh-column deployed in aqueous solution, >90% removal of As(III) was achieved within 5 days at initial As (100 mg L-1) of two orders of magnitude higher than in most paddy soil solutions (1-1538 µg L-1). By applying Fh-column in a seriously contaminated paddy soil (102 mg As kg-1), porewater As showed stepwise decreases from 2727 µg L-1 to 129-1455 µg L-1 at a distance-dependent manner over four intermittent extractions during 91 days. Soil DGT-As exhibited similar spatiotemporal changes to porewater As. After four extractions, 17.8% of total soil As was removed by Fh-column in a 10 cm radius range on average and ∼1/3 of As bound to amorphous and crystalline Fe/Al oxides was depleted, which accounted for 88.7% of decline in total soil As. With the post-extracted soil, a 48% lower As accumulation in rice seedlings and a 65% decline in bulk soil DGT-As were attained. This study provides a conceptual foundation for rapid removal of high soluble As by Fh-columns from flooded soils, improving seriously As-contaminated paddies to sustainable resources for safe food production.

Felt Emotion Elicited by Music: Are Sensitivities to Various Musical Features Different for Young Children and Young Adults?

In the present study, we extended the issue of how people access emotion through nonverbal information by testing the effects of simple (tempo) and complex (timbre) acoustic features of music on felt emotion. Three- to six-year-old young children (n = 100; 48% female) and university students (n = 64; 37.5% female) took part in three experiments in which acoustic features of music were manipulated to determine whether there are links between perceived emotion and felt emotion in processing musical segments. After exposure to segments of music, participants completed a felt emotion judgment task. The chi-square test showed significant tempo effects, ps < .001 (Exp. 1), and strong combined effects of mode and tempo on felt emotion. In addition, strength of these effects changed across age. However, these combined effects were significantly stronger under the tempo-and-mode consistent condition, ps < .001 (Exp. 2) than inconsistent condition (Exp. 3). In other words, simple versus complex acoustic features had stronger effects on felt emotion, and that sensitivity to these features, especially complex features, changed across age. These findings suggest that felt emotion evoked by acoustic features of a given piece of music might be affected by both innate abilities and by the strength of mappings between acoustic features and emotion.

Cadmium accumulation in rice (Oryza sativa L.) alleviated by basal alkaline fertilizers followed by topdressing of manganese fertilizer.

Rice is a main source of dietary cadmium (Cd), thus, how to reduce the Cd concentration in brown rice has received extensive attention worldwide. In three acidic paddy soils slightly to moderately contaminated with Cd, a series of field experiments were conducted to evaluate the effects of different proportions of nitrogen-phosphorus-potassium (N-P-K) fertilizer (urea, calcium magnesium phosphate, and potassium carbonate, respectively) alone or coupled with a topdressing of manganese (Mn) fertilizer at the tillering stage on reducing Cd bioavailability in soil and uptake in rice. The rational application of N-P-K fertilizer not only provided the basic nutrients to promote the normal growth of rice but also increased soil pH and thereby reduced the Cd bioavailability in soil. The Mg(NO3)2-extracted Cd concentrations in the three soils were reduced by 26.46-56.53%, while TCLP-extracted Cd were reduced by 19.87-45.41%, with little influence on soil cation exchange capacity (CEC) and organic matter (OM). The application of Mn fertilizer at the tillering stage increased Mn and Cd sequestration in the iron plaque. The Mn content in iron plaque increased by 15.71-58.67% and a significant positive correlation between Cd and Mn was observed at the three sites. Collectively, this combined method of fertilization significantly reduced Cd accumulation in rice tissues, the Cd concentrations in roots of treated plants decreased by 11.18-37.78%, whereas the concentrations in straw decreased by 13.16-41.03%. Particularly to brown rice, in which accumulation decreased by 25.19-44.70%, 37.35-47.84%, and 38.00-60.88% in three typical paddy fields, but no significant effect was observed for the Cd translocation factors (TF) among rice tissues. Thus, the basal application of combined urea and alkaline inorganic fertilizers followed by topdressing of Mn fertilizer may be a promising and cost-effective tactics for the remediation of Cd-contaminated paddy soils.

Variations in iron plaque, root morphology and metal bioavailability response to seedling establishment methods and their impacts on Cd and Pb accumulation and translocation in rice (Oryza sativa L.).

Global rice production is undergoing a shift from traditional seedling transplanting to direct seeding. There are also serious global challenges caused by heavy metal pollution in grain. To evaluate heavy metal accumulation in rice under different seedling establishment methods, we conducted field experiments with manual transplanting (MT), seedling throwing (ST) and direct seeding (DS). Data revealed that DS method enhances cadmium (Cd) and lead (Pb) accumulation in roots, straw, and brown rice. In particular, the Cd concentration in DS brown rice was 35.4% and 22.5% higher than in MT and ST methods, respectively; the concentration of Pb in DS brown rice was 1.97 times higher than in MT. The reasons for these observations are that DS rice root systems have finer diameters, larger specific surface areas, larger specific root lengths, more root tips, and reducing Fe plaque formation on root surface while DS rice roots formed in the upper soil layer and exhibited higher Cd and Pb bioactivity within the rhizosphere soil. Collectively, here we show for the first time that the shift in seedling establishment methods from transplanting to direct seeding also have played a partial contribution in the observed increased severity of heavy metal pollution in rice levels.

Felt emotion elicited by music: are sensitivities to various musical features different for young children and young adults?

In the present study, we extended the issue of how people access emotion through nonverbal information by testing the effects of simple (tempo) and complex (timbre) acoustic features of music on felt emotion. Three- to six-year-old young children (n = 100; 48% female) and university students (n = 64; 37.5% female) took part in three experiments in which acoustic features of music were manipulated to determine whether there are links between perceived emotion and felt emotion in processing musical segments. After exposure to segments of music, participants completed a felt emotion judgment task. The chi-square test showed significant tempo effects, ps < .001 (Exp. 1), and strong combined effects of mode and tempo on felt emotion. In addition, strength of these effects changed across age. However, these combined effects were significantly stronger under the tempo-and-mode consistent condition, ps < .001 (Exp. 2) than inconsistent condition (Exp. 3). In other words, simple versus complex acoustic features had stronger effects on felt emotion, and that sensitivity to these features, especially complex features, changed across age. These findings suggest that felt emotion evoked by acoustic features of a given piece of music might be affected by both innate abilities and by the strength of mappings between acoustic features and emotion

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Cadmium accumulation in winter crops and the assessment of paddy soil phytoremediation in southern China.

Heavy metal pollution, in particular with cadmium (Cd), threatens both the environment and human health. The phytoremediation of contaminated soil is one recently developed eco-friendly technique that can be applied to mitigate this issue. Repairing Cd-contaminated paddy soil during the fallow winter period can ensure future rice production while reducing heavy metal pollution. Seven winter crops were planted in this study to investigate the accumulation of this metal in mid-level Cd and low-level lead (Pb) and zinc (Zn)-contaminated paddy soils. Results show that after 4 or 5 months of growth, all crops had become moderately tolerant to toxicity; indeed, shoot Cd bioconcentration factor (BCF) values were 37.4, 17.0, 11.5, 10.5, 5.8, 3.9, and 1.4 for Sedum alfredii (SA), Witloof chicory (WC), edible-leaf beet (EB), Cardamine hupingshanensis (CH), leafy mustard (LM), oil mustard (OM), and perennial ryegrass (PR), respectively, while shoot Pb and Zn BCF values were less than 1 and 5, respectively. And SA, WC, EB, and CH all had higher shoot Cd accumulation capacities, especially SA in which the level reached 53.9 mg kg-1. The calculation results of restoration potential show that it will take at least 5 years for WC, 7 years for SA and EB, and 10 years for CH to reach the repair target. These results show that it is possible to grow winter crops to repair soil Cd pollution, with WC, EB, CH, and SA, the best candidates for making full use of fallow periods while simultaneously achieving soil phytoremediation. The results of this study will prove useful for establishing a new summer production model by ensuring the winter repair of contaminated paddy soil.

Phytoextraction of Cd from a contaminated soil by tobacco and safe use of its metal-enriched biomass.

Successful phytoextraction produces a large quantity of contaminated biomass, which will cause secondary pollution unless properly treated. This study investigated the disposal of contaminated tobacco biomass after phytoextraction. We detected significantly high Cadmium concentrations in tobacco, especially in their stems and leaves. From the latter, nearly all the Cd and nicotine were removed by extractions with 0.5% HCl + 70% ethanol, and the nicotine completely recovered via steam distillation, whereas the protein content remained unaffected in the leaves, thus making them safe for use as animal feed. The highest biochar yield was 47%, obtained after slow pyrolysis at 300 °C. In this case, the biochar contained the highest amount of nutrients and metals. From stem biochar, 87% of Cd and a large amount K along with several other elements were extracted by deionized water at pH 1. After acid-extraction, metals were formed precipitation and then separated from the K-enriched solution when the pH was adjusted to 11 by using drops of 40% KOH. Therefore, with improved technology to remove metals and recover nutrients and nicotine from biomass, tobacco is an ideal candidate as profit yielding crop for use in phytoextraction while also providing renewable resources.

Experiments on Temperature Changes of Microbolometer under Blackbody Radiation and Predictions Using Thermal Modeling by COMSOL Multiphysics Simulator.

In this study, we study a heat transfer model, with the surface of the microbolometer device receiving radiation from blackbody constructed using a COMSOL Multiphysics simulator. We have proposed three kinds of L-type 2-leg and 4-leg with the pixel pitch of 35 µm based on vanadium oxide absorbent membrane sandwiched with top passivated and bottom Si3N4 supporting films, respectively. Under the blackbody radiation, the surface temperature changes and distributions of these samples are simulated and analyzed in detail. The trend of change of the temperature dependent resistance of the four kinds of bolometer devices using the proposed heat transfer model is consistent with the actual results of the change of resistance of 4 samples irradiated with 325 K blackbody located in the front distance of 5 cm. In this paper, ΔT indicates the averaged differences of the top temperature on the suspended membrane and the lowest temperature on the post of legs of the microbolometers. It is shown that ΔT ≈ 17 mK is larger in nominal 2-leg microbolometer device than that of 4-leg one and of 2-leg with 2 µm × 2 µm central square hole and two 7.5 µm × 2 µm slits in suspended films. Additionally, only ΔT ≈ 5 mK with 4-leg microbolometer device under the same radiated energy of 325 K blackbody results from the larger total thermal conductance.

Phytoextraction of cadmium-contaminated soil and potential of regenerated tobacco biomass for recovery of cadmium.

The aim of this study was to estimate the influence of regenerated tobacco on the extraction of Cd from two acidic soils as well as to address the problem of how to deal with contaminated leaves following phytoextraction. Results showed that a coppicing tobacco led to a decline in Cd concentration in regenerated leaves and stalks when plants were grown in pots, but increased concentrations in regenerated lower and middle leaves when plants were grown under field conditions. The highest recorded bioconcentration factors in Chaling and Guanxi soil were 37.53 and 19.21 in lower leaves in the field, respectively. Total Cd extraction efficiency in practice (9.43% for Chaling soil and 6.24% for Guanxi soil) under field conditions confirmed our theoretical calculations (10.0% for Chaling soil and 6.73% for Guanxi soil). Use of a 0.5% hydrochloric acid(HCl) solution was sufficient to reduce Cd (98.4%) in tobacco leaves to permissible levels as required by the Hygienic Standard for Feeds in China (≤0.5 mg kg-1). Regenerated tobacco has the potential to allow cultivation of Cd contaminated farmland to produce animal feed, assist in lowering total Cd content of soil, and allow income generation for farmers.