[Effects of Chlorine-based and Sulfur-based Fertilizers on Rice Bioavailability of Cd in Soils].

To explore the effects of single or combined application of chlorine-and sulfur-based fertilizers on rice bioavailability of Cd in soils, pot experiments with reddish clayey soil (developed from quaternary red clay parent materials) under three exogenous Cd levels (0, 0.5, and 2.0 mg·kg) were conducted.

[Effects of Chelate GLDA on the Remediation of Cadmium Contaminated Farmland by Schum].

In order to clarify the effects of chelate tetrasodium glutamate diacetate (GLDA) on the remediation of cadmium (Cd) contaminated farmland by Schum, GLDA was applied in different methods within 60 days:total application doses of 585, 1170, and 2340 kg·hm were equally divided into 1-4 applications, respectively, and the time intervals of 2-4 applications were 30, 20, and 15 days, respectively. The biomass, Cd content, and amount of Cd extracted from aboveground parts of Schum, in addition to the pH, dissolved organic carbon (DOC) mass concentration, and other indicators in soil were analyzed. The results showed that the biomass and Cd content of the aboveground parts of Schum increased significantly when GLDA was applied many times at a low application dose.

[Effects of Water Management on Soil Properties and Cd Behavior of Typical Paddy Soils].

To explore the effects of water management mode on Cd environmental behavior in different parent-material-developed paddy soils, two parent-material-developed paddy soils (yellow clayey soil and granitic sandy soil) under three exogenous Cd levels (0.5, 2.0, and 5.

Effects of Cd-resistant bacteria and calcium carbonate + sepiolite on Cd availability in contaminated paddy soil and on Cd accumulation in brown rice grains.

A pot experiment was conducted to evaluate the effects of combined application of cadmium (Cd)-resistant bacteria (J) and calcium carbonate + sepiolite (G) on both Cd bioavailability in contaminated paddy soil and on Cd accumulation in rice plants. Adding the mixture (J + G) to the soils significantly increased soil pH, decreased extractable Cd contents, and increased Fe/Mn-oxide Cd and organic-bound Cd contents. The applying of J + G, J and G decreased Cd contents in various rice tissues (roots, stems and leaves, husks, and brown rice grains) to different degrees.

[Cd Balance Analysis of a Typical Rice Paddy System in Central Hunan].

By conducting field positioning experiments, we studied the development trend of Cd pollution in a typical paddy system. The samples of atmospheric deposition and irrigation water were collected monthly from November 2015 to November 2018 during which fertilizer, soil, and rice samples were also collected. The Cd concentration in the samples was monitored and analyzed to conduct research on the balance between Cd inputs and outputs in a typical paddy system in Hunan Province.

Cadmium and arsenic accumulation during the rice growth period under in situ remediation.

Rice (Oryza sativa L.) planted in cadmium (Cd)- and arsenic (As)-contaminated soil is considered the main source of dietary Cd and As intake for humans in Southeast Asia and thereby poses a threat to human health. Minimizing the transfer of these pollutants to rice grain is an urgent task for environmental researchers.

[Effect of Phosphorus Addition on the Abundance of Autotrophic CO-Fixation Microorganisms in Rhizospheric Soil from a Phosphorus-Limited Paddy Field].

A rice pot experiment was conducted to investigate the effect of phosphorus addition on the abundance of autotrophic CO-fixation microorganisms using phosphorus-limited paddy soil from the Changsha Observation and Research Station for the Agricultural Environment. Rice seedlings were transplanted in the paddy soil with or without phosphorus addition, corresponding to P-treated-pot (P) or control pot (CK), respectively. Rhizosphere soils were collected from the P and CK treatments during the tillering and shooting stages.

[Differences in Cd Accumulation in Typical Soils Under the Double Rice System].

Pot experiments were used to study the differences of Cd uptake and accumulation in double-cropping rice in typical soil types. To analyze the soil availability of Cd (DTPA-Cd) in soils and the Cd accumulation in double-cropping rice at different growth stages of the rice, we conducted pot experiments that selected the yellow clayey soil (paddy soil developed from plate shaley parent materials) and the granitic sandy soil (paddy soil developed from granitic parent materials). Exogenous Cd was added with gradients of 0, 0.

[Dynamics of Rice Photosynthesized Carbon Input and Its Response to Nitrogen Fertilization at the Jointing Stage: C-CO Pulse-labeling].

Photosynthesized carbon (C) is an important source of soil organic C in paddy fields, and its input and distribution are affected by rice growth and soil fertility. Fertilizer application plays an important role in rice growth. The C pulse-labeling method was used to quantify the dynamics and distribution of input photosynthesized C in the rice-(rhizosphere-and bulk-) soil system and its response to nitrogen fertilizer (N) application.

[Effects of a Tribasic Amendment on Cadmium and Arsenic Accumulation and Translocation in Rice in a Field Experiment].

An paddy field experiment was carried out to study the influence of a tribasic amendment (QFJ, hydroxyapatite+zeolite+biochar) on Cd and As accumulation and translocation in rice grown in soil contaminated with cadmium and arsenic, with the concentrations of soil Cd and As being 3.58 mg·kg and 124.79 mg·kg, respectively.

Effects of an additive (hydroxyapatite-biochar-zeolite) on the chemical speciation of Cd and As in paddy soils and their accumulation and translocation in rice plants.

A pot experiment was carried out to investigate the remediation of paddy soils contaminated with both Cd and As. The effects of a soil additive (HZB: hydroxyapatite + zeolite + biochar) on the chemical speciation of Cd and As in the soil and on the accumulation and translocation of these two elements in rice plants were studied. The application of HZB decreased the concentration of acid-extractable Cd in the soil by 7.

[Effects of Different Water Managements and Soil Eh on Migration and Accumulation of Cd in Rice].

A pot experiment was conducted to study the effects of four modes of water managements on soil Eh values,bioavailability of soil Cd,migration and accumulation of Cd in rice.These four modes of water managements were moistening throughout the entire period of rice growth (M),moistening before filling stage and flooding after filling stage (M-F),flooding before filling stage and moistening after filling stage (F-M),and flooding throughout the entire period of rice growth (F).The results indicated that the exchangeable contents of Cd increased firstly and then declined with the soil Eh values changing from negative to positive.

[Provoking Effects of Exogenous Zn on Cadmium Accumulation in Rice].

Pot experiments were carried out to study the influences of different concentrations of exogenous Zn on accumulation of Cd in various rice organs of low Cd accumulation cultivar Xiang-Wanxian 12 (XWX12) and high Cd accumulation cultivar Wei-You 46 (WY 46) exposed to soil with medium and serious Cd pollution. The results showed that:In the soil with medium Cd pollution, Cd contents in various rice organs of two rice varieties were increased by exogenous Zn, and the Cd contents in brown rice of XWX12 and WY46 were increased by 125.0% -275.

[Comparison of the Persistence of a Combined Amendment Stabilizing Pb, Cd, Cu and Zn in Polluted Paddy Soil].

A three-year in-situ experiment was conducted in a paddy soil near a mining area in southern Hunan in order to study the persistence of combined amendment of limestone+sepiolite (marked as LS) stabilizing Pb, Cd, Cu and Zn in polluted paddy soil. LS with ratios of 0, 2, 4, and 8 g·kg was applied once to the paddy soil, and rice was subsequently planted for three consecutive years of 2012 (first season), 2013 (second season), and 2014 (third season). The experimental results indicated that:①LS significantly increased soil pH values for all three seasons, and the enhancement ranked as follows:first season > second season > third season.

A three-year in-situ study on the persistence of a combined amendment (limestone+sepiolite) for remedying paddy soil polluted with heavy metals.

In order to study the persistence of a combined amendment (LS, limestone+sepiolite) for remedying paddy soil polluted with the heavy metals Pb and Cd, a three-year in-situ experiment was conducted in a paddy soil near a mining area in southern Hunan, China. LS was applied at rates of 0, 2, 4, and 8g/kg (w/w); rice was subsequently planted for the three consecutive years of 2012 (first season), 2013 (second season), and 2014 (third season). Experimental results indicated that LS significantly increased soil pH values for all three seasons, and the enhancement ranked as follows: first season>second season>third season.

Accumulation of Heavy Metals in Vegetable Species Planted in Contaminated Soils and the Health Risk Assessment.

The objectives of the present study were to investigate heavy metal accumulation in 22 vegetable species and to assess the human health risks of vegetable consumption. Six vegetable types were cultivated on farmland contaminated with heavy metals (Pb, Cd, Cu, Zn, and As). The target hazard quotient (THQ) method was used to assess the human health risks posed by heavy metals through vegetable consumption.

[In-situ Study on Effects of Combined Amendment on Translocation Control of Pb and Cd in Soil-Vegetable System].

An in-situ study aiming at remedying arid land complexly polluted with Pb and Cd by using combined amendment LS (a mixture of limestone and sepiolite with a ratio of 2 : 1) was conducted in a mining area in southern Hunan, China. The main objectives of this study were to discuss the effects of LS application at different amounts (0 , 2, 4, 8 g x kg(-1)) on the adsorption and accumulation of Pb and Cd in eggplant and amaranth, and to control the translocation and transportation of Pb and Cd among different parts of eggplant and amaranth. The results showed that: (1) Application of LS significantly increased soil pH values and decreased contents of exchangeable Pb and Cd in soil.

[Vertical Distribution Characteristics of Typical Forest Soil Organic Nitrogen in Dawei Mountain].

To clarify altitudinal gradient of subtropical forest soil total nitrogen and organic nitrogen, soil samples were collected per 10 cm on soil profile (0-100 cm) in Dawei Mountain, researched the variation of soil organic nitrogen and correlation with soil physical and chemical properties. The results showed that: (1) Total nitrogen, acid hydrolysable organic nitrogen and soluble organic nitrogen decreased with the increase of depth, content of each component in mountain granite yellow-brown soils was much higher affected by altitude; (2) The average percentage of soil organic nitrogen to total nitrogen was 97.39% ± 1.

[Transformation and mobility of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages of rice].

Speciation and bioavailability of arsenic in the rhizosphere and non-rhizosphere soils at different growth stages (tillering stage, jointing stage, booting stage, filling stage and maturing stage) of rice (Oryza sativa L.) were studied using toxicity characteristic leaching procedure (TCLP) and arsenic speciation analysis. Pot experiments were conducted and the soil samples were taken from a certain paddy soil in Hunan Province contaminated by mining industry.

[Dynamics of the mineralization and transformation of rice photosynthesized carbon in paddy soils--a batch incubation experiment].

Photosynthesized carbon is an important part in C cycling of "atmosphere-plant-soil" and is the source of soil organic carbon (SOC), but its mineralization and transformation dynamics in paddy soils remains still unclear. Therefore, a batch incubation experiment was conducted to investigate the mineralization and transformation of rice photosynthesized carbon in paddy soils after rice harvest. The results showed that the mineralization rate of native SOC ranged from 4.

[Dynamics of labeled substrate N by microorganism and soil clay immobilized and its residue fractions in typical paddy soils in Dongting Lake floodplain].

Dynamics of immobilization of the labeled substrate N by microorganism and soil clay and its residue fractions in soils from the plough layers of two subtropical paddy soils (Reddish clayey soil, Purple alluvial soil) in the Dongting Lake floodplain were studied. A laboratory-flooded incubation experiment was composed of three treatments: control (CK), labeled ammonium sulphate group (15NA) and the combined of labeled ammonium sulphate and rice straw group (S + 15NA). During the incubation, microbial biomass N (BN) increased firstly and then those decreased and tended to stable subsequently, while the content of fixed ammonium changed little.

[Effects of long-term application of fertilizers on soil microbial biomass nitrogen and organic nitrogen components in subtropical paddy soils].

The effect of long-term fertilization on soil organic nitrogen components and microbial biomass nitrogen (B(N)) in paddy soils from two experiment sites in Hunan province were studied. Soil samples were collected from the plough layers of different fertilizer treatments. Soil B(N) was measured by the fumigation-extraction method, and soil organic N was fractionated by acid hydrolysis-distillation method according to the scheme of Bremner (1965).