Iron oxide-biochar composites have been widely used in removal of phosphate from water, however, their effects on phosphorus retention and decrease leaching are unclear in saline-alkaline soils. We ...utilized rice straw-derived biochar modified with ferrous chloride (Fe(II)) and ferric chloride (Fe(III)) to study the potential mechanisms of phosphorus retention and leaching under field conditions. Results showed that the Fe(II) biochar exhibited superior phosphate adsorption capacity (39.2 mg g−1) over the unmodified. In addition, Fe(III) biochar was relatively insensitive to pH and competed anions. This might be due to iron in Fe(II) biochar that exists primarily in an amorphous state as FeOOH, which enhanced its ability to adsorb phosphate because it has high isoelectric points. Crystals of Fe2PO5 and (PO3)3 were formed in the Fe(II) and Fe(III) biochars, respectively. Electrostatic attraction and ligand exchange contributed to phosphate adsorption. In the column leaching experiments, all treatments were found to significantly increase the phosphorus content in 0–20 cm soil compared to Control, especially with Fe(II) biochar amendment. Fe(II) biochar decreased leaching by 86.4%. In the field experiments, Fe(II) and Fe(III) biochar increased the available phosphorus by 78.6% and 90.3%, respectively. Overall, application of iron modified biochar to saline-alkaline soils promoted phosphorus adsorption and decreased leaching.
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•Iron in Fe(II)-biochar existed primarily in an amorphous state as FeOOH.•The adsorption capacity of Fe(II)-biochar is 2.4 times higher than biochar.•Iron modified biochar adsorption capacity was not insensitive to pH changes.•Iron modified biochar increased the available phosphorus content in soil.
This article argues that the Chinese Communist Party has adopted a unique understanding of the people. Unlike the liberal view, which generally considers the people a nonpolitical and positive ...entity, the party views the people as essentially political. The party’s political understanding of the people, this article argues, is consistent with the very nature of the people. Viewed from the political understanding of the people and representing the people, the party’s theories of “contradictions among the people,” of the “mass line,” and of distinctions among different classes and individuals are consistent with self-governance by the people. The party’s theories are not inherently totalitarian, antidemocratic, and arbitrary, as liberal theorists argue.
This article argues that the Chinese Communist Party has adopted a unique understanding of law. Unlike the liberal view and the unwritten constitution view, which generally consider law as positive ...norms that exist independently of politics, the party understands law as a reflection of the party's and the people's will and a form of the party's and the people's self-discipline. In the party's view, liberal rule of law theories are self-contradictory, illusive, and meaningless. This article argues that the party views the people as a political concept and itself as a political leading party, marking a fundamental difference from a competitive party in a parliamentary system. The legitimacy of the party's dominant role and the party-state regime, therefore, depends on whether the party can continue to provide political momentum to lead the people and represent them in the future.
Methods
Soil was sampled (0–20 cm) from a 5-year Yellow River Delta paddy field experiment: no fertilizers (Control), mineral fertilizers (NPK), and NPK plus organic fertilizer (soybean and bean ...litter) applied at rates of 450 and 900 kg C ha
− 1
(NPKC1 and NPKC2). The aggregate size, labile carbon fractions and root growth were investigated in combination with microbial community structure by high-throughput sequencing.
Results
NPKC1 and NPKC2 fertilization decreased Na
+
content, but increased available nitrogen, phosphorus and Ca
2+
contents. Macroaggregate formation was increased under NPKC1 (by 28 %) and NPKC2 (by 62 %) fertilization through increase of labile carbon fractions (particularly microbial biomass carbon), as well as better root growth. NPKC1 and NPKC2 fertilization increased microbial diversity and enriched the microbial community towards taxa responsible for aggregate stability (e.g.,
Actinobacteria
and
Ascomycota
). RDA revealed that dissolved organic carbon content was the main factor affecting microbial community composition.
Conclusions
Combined mineral and organic fertilizers decreased Na
+
content, increased macroaggregates due to broader microbial diversity, increased contents of labile organic carbon and Ca
2+
. Consequently, combined organic and mineral fertilization were the best practice to increase microbial biomass and labile carbon fractions that strongly contribute to aggregate formation in saline-alkaline soil.
Aims
Soil structure is a key factor in sustainable agriculture, especially for saline-alkaline soils, because Na
+
destroys clay minearls and colloids, and thus, prevents the aggregate formation. We assessed the effects of organic amendments in combination with mineral fertilizers on chemical properties, microbial community composition and aggregate formation in a typical saline-alkaline soil.
Cadmium (Cd) has become the primary pollution factor in farmland, which seriously threatens crop growth and food safety. A pot experiment was conducted to investigate the effect of combined ...application with biochar and P fertilizer on soil Cd availability and translocation, in which biochar was 0 (C
0
) and 20 g kg
−1
(C
20
), P fertilizer was 0 (P
0
), 20 (P
20
), and 40 mg P kg
−1
(P
40
). Results showed that, compared with C
0
level, the content of DTPA-Cd in soil was significantly decreased with biochar addition after 60 days of cultivation, under C
20
level, soil DTPA-Cd in C
20
P
40
treatment were significantly increased. Under both C levels, the percentage of exchangeable Cd fraction at P
40
rate was significantly lower than that at P
20
rate, because the excess P in soil could precipitate Cd. The percentage of residual-Cd fraction was significantly increased with the combined addition of biochar and P fertilizer, particularly in C
20
P
40
treatment, which was 75.95%, while it was only 61.65% in C
0
P
0
treatment. The Cd translocation factor (TF) and bioconcentration factor (BCF) were also significantly reduced in C
20
P
20
and C
20
P
40
treatments compared with C
0
P
0
treatment. Therefore, the combined high P and biochar application was a good choice in inhibiting soil Cd availability and plant Cd uptake, which benefited to the safe utility of the Cd contaminated soil.
Increasingly, algorithms challenge legal regulations, and also challenge the right to explanation, personal privacy and freedom, and individual equal protection. As decision-making mechanisms for ...human-machine interaction, algorithms are not value-neutral and should be legally regulated. Algorithm disclosure, personal data empowerment, and anti-algorithmic discrimination are traditional regulatory methods relating to algorithms, but mechanically using these methods presents difficulties in feasibility and desirability. Algorithm disclosure faces difficulties such as technical infeasibility, meaningless disclosure, user gaming and intellectual property right infringement. And personal data empowerment faces difficulties such as personal difficulty in exercising data rights and excessive personal data empowerment, making it difficult for big data and algorithms to operate effectively. Anti-algorithmic discrimination faces difficulties such as non-machine algorithmic discrimination, impossible status neutrality, and difficult realization of social equality. Taking scenarios of algorithms lightly is the root cause of the traditional algorithm regulation path dilemma. Algorithms may differ in attributes due to specific algorithmic subjects, objects and domains involved. Therefore, algorithm regulation should be developed and employed based on a case-by-case approach to the development of accountable algorithms. Following these development principles, specific rules can be enacted to regulate algorithm disclosure, data empowerment, and anti-algorithmic discrimination.
•Biochar significantly increased the sequestration of SOC in saline soil.•Macroaggregate in organic fertilizer and straw were higher than that in biochar.•CMI values was greater in straw compared ...with organic fertilizer and biochar.•Organic amendments affected exchangeable cation distribution in aggregates.
Organic amendments are a recyclable resource and can improve soil quality and carbon (C) sequestration, however, the difference in their effects on soil aggregate formation and C sequestration in saline-alkaline soils are less studied. We examined the effects of organic amendments to saline rice paddy fields with 4 treatments: (i) basal paddy soil (CK) lacking amendments (ii) organic fertilizer (OF) treatment at 910 kg C ha−1 from soybean litter and beans (iii) rice straw (RS) treatment at 3600 kg C ha−1 and (iv) rice straw-derived biochar (RS-biochar) treatment at 3600 kg C ha−1. All organic amendments significantly increased the soil organic C (SOC) stock in the 0–30 cm soil layer compared to CK. The SOC stock in the biochar treatment increased by 6.2 and 40.4% over the OF and RS amended treatments, respectively. This was most likely due to the greater levels of aromatic C in RS-biochar at 1.22 and 1.24 times greater than for the other organic amendments, respectively. Soil aggregates of 2–8 mm at 0–15 cm in the OF and RS amended soils were 38.3 and 58.2%, respectively, higher than that from the RS-biochar treatment. The mean weight diameter (MWD) in the OF and RS treatments were 35.4% and 45.8% higher than for the RS-biochar, respectively. MWD was significantly negatively correlated with soil exchangeable Na (p < 0.05). This indicated OF and RS were better than RS-biochar in improving soil aggregate stability. In addition, the C management index values for RS were 21.6 and 45.8% greater than for OF and RS-biochar in the 0–15 cm soil layer, respectively. These data indicated that saline soil aggregate formation and C sequestration improved after organic amendments application, which caused the exchangeable Na to decrease and affected its distribution in aggregates, and changed the composition of C functional groups.
Acoustic metamaterials are materials with artificially designed structures, which have characteristics that surpass the behavior of natural materials, such as negative refraction, anomalous Doppler ...effect, plane focusing, etc. This article mainly introduces and summarizes the related research progress of acoustic metamaterials in the past two decades, focusing on meta-atomic acoustic metamaterials, metamolecular acoustic metamaterials, meta-atomic clusters and metamolecule cluster acoustic metamaterials. Finally, the research overview and development trend of acoustic metasurfaces are briefly introduced.
Adequate silicon (Si) can greatly boost rice yield and improve grain quality through alleviating stresses associated with heavy metals and metalloids such as arsenic (As) and cadmium (Cd). The soil ...plant-available Si is relatively low in South China due to severe desilicification and allitization of the soils in this region. Conversely, pollution of heavy metals and metalloids in the soils of this region occurs widely, especially As and Cd pollution in paddy soil. Therefore, evaluating the plant availability of Si in paddy soil of South China and examining its correlation with the availability of heavy metals and metalloids are of great significance. Accordingly, in our study, 107 pairs of soil and rice plant samples were collected from paddy fields contaminated by As and Cd in South China. Significantly positive correlations between Si in rice plants and Si fractions in soils extracted with citric acid, NaOAc-HOAc buffer, and oxalate-ammonium oxalate buffer suggest that these extractants are more suitable for use in extracting plant-available Si in the soils of our present study. Significantly negative correlations between different Si fractions and As or Cd in rice plant tissues and negative exponential correlations between the molar ratios of Si to As/Cd in rice roots, straws, husks or grains and As/Cd in rice grains indicate that Si can significantly alleviate the accumulation of As/Cd from soils to the rice plants. Finally, a contribution assessment of soil properties to As/Cd accumulation in rice grains based on random forest showed that in addition to Si concentrations in soil or rice plants, other factors such as Fe fractions and total phosphorus also contributed largely to As/Cd accumulation in rice grains. Overall, Si exhibited its unique role in mitigating As or Cd stress in rice, and our study results provide strong field evidence for this role.
The effects of soil extractable and plant Si on As and Cd availabilities to rice were investigated.
Both arbuscular mycorrhizal (AM) fungi and phosphate solubilizing bacteria (PSB) are involved in phosphorus (P) mobilization and turnover but the influence of their interaction on organic P ...mineralization in the root free soil (hyphosphere) have been little studied. We investigated the interactive effects of an AM fungus (Rhizophagus irregularis, RI) and/or PSB (Pseudomonas alcaligenes, PA) on phytate mineralization and subsequent transfer to the host plant (Medicago sativa) using a two-compartment microcosm with a central 30 μm nylon mesh barrier. The root growth compartment containing 5 mg inorganic P (Pi, KH2PO4) kg−1 soil was inoculated with RI or uninoculated and the AM fungal hyphal soil containing 75 mg organic P (Po, Na-phytate) plus 0 or 5 mg Pi kg−1 soil was inoculated with PA or uninoculated. Sole inoculation with RI increased shoot P content compared with the uninoculated treatment and dual inoculation with both RI and PA did not increase shoot P compared with sole RI inoculation. Sole PA inoculation significantly increased microbial biomass P (MBP). Compared with sole PA inoculation soil MBP increased under zero-Pi addition but decreased under 5 mg Pi kg−1 soil addition in the dual inoculation RI/PA treatment. The uninoculated microcosms had the lowest acid phosphatase activity and the highest phytate-P remaining in the soil. Inoculation with PA led to higher acid phosphatase activity and lower phytate-P than did RI. Dual RI/PA inoculation had the highest acid phosphatase activity and the lowest phytate-P remaining in the soil. Addition of 5 mg Pi kg−1 soil to the hyphal compartment decreased phytate-P remaining in the RI and/or PA treatments. The phytate-P remaining in the soil was negatively correlated with soil acid phosphatase activity or MBP in the presence of RI but there was no correlation between shoot P and soil phytate-P. In conclusion, our results indicate that the mineralization of soil phytate was promoted by the interaction between the AM fungus and its hyphosphere PSB.
•Hyphosphere AM fungus–PSB interaction on phytate mineralization is studied.•PSB play a major role in phytate mineralization.•PSB competes for P with AM fungus in available P limited soil.•AM fungus primes PSB on phytate mineralization and turnover.
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