Bayesian risk prediction model: An accessible strategy to predict cadmium contamination risk in wheat grain grown in alkaline soils.

Excessive cadmium (Cd) concentration in wheat grain is becoming a widespread concern in China. Considering the complexity of Cd transfer in the soil-wheat system, how the Cd risk in wheat grain be accurately predicted from the limited details available is of great significance for the risk management of Cd. Bayes' theory could leverage existing data by combining prior information and observational data, providing a promising strategy with which to calculate a more robust posterior probability of a grain sample exceeding the food safety standard (FSS) for Cd (0.1 mg kg-1). In the current study, a risk prediction model, based on Bayes' theory, was established to achieve a more accurate prediction of the wheat grain Cd risk from a limited number of soil parameters. The risk prediction model could predict the risk probability of wheat grain with a Cd concentration exceeding the FSS under a given soil concentration of either total Cd or diethylenetriaminepentaacetic acid (DTPA)-extractable Cd. Soil total Cd concentration proved to be a better variable for the model with greater predictive accuracy. The model predicted that fewer than 5% of the wheat grain would have a Cd concentration exceeding the FSS when grown in soil with a total Cd concentration of less than 0.299 mg kg-1. The risk probability rose significantly to 50% when the soil total Cd reached 0.778 mg kg-1. The accuracy of the model was greater than the widely applied multiple linear regression model, whereas previously published data from similar soil conditions also confirmed that the Bayesian model could predict wheat Cd risk with minimal error. The proposed model provides an accurate, accessible and cost-effective methodology for predicting Cd risk in wheat grown in alkaline soils before harvest. The wider application to other soil conditions, crops or contaminants using the Bayesian model is also promising for risk management authorities.

[Effect of Zinc Fertilizer Application on Cadmium Accumulation in Wheat Grain and Its Application Risk].

The interaction of zinc (Zn) and cadmium (Cd) is an important research direction in the prevention and control of Cd pollution of wheat in recent years. In this study, a typical wheat field in North China was selected as the object to explore the control effect and application risk of Zn fertilizer on Cd pollution in a soil-wheat system through field experiments. The results showed that under the treatment of a low dosage of Zn, the Cd concentrations in wheat grains in Jiyuan City and Kaifeng City decreased by 33.4% and 25.3% compared with those in the control, respectively. By contrast, Cd concentrations in wheat grains treated with a high dosage of Zn increased by 22.4% and 34.2% compared with that of the low-dosage Zn treatment. After the application of Zn, the total amount and available Zn concentrations increased significantly, and Cd was partially activated in these two locations. Canonical correlation analysis (CCA) showed that when the Zn concentrations in the soils were less than 200 mg·kg-1, soil Zn was the main factor affecting Cd accumulation in the soil-wheat system, whereas when Zn concentrations in soils were greater than 200 mg·kg-1, the activation of soil Cd was the main factor affecting Cd accumulation in wheat grains. Regression analysis showed that when the soil Cd/Zn ratio decreased to 0.0089 (low dosage of Zn), Zn and Cd showed an antagonistic effect, whereas when the soil Cd/Zn ratio decreased to 0.0078 (high dosage of Zn), Zn and Cd showed a synergistic effect. According to the characteristics of regional Cd pollution, adjusting the amount of Zn fertilizer can improve the efficiency of pollution control and avoid aggravating the harm of Cd pollution.

A machine learning based approach for estimating site-specific partition coefficient Kd of organic compounds: Application to nonionic pesticides.

The partitioning coefficient Kd for a specific compound and location is not only a key input parameter of fate and transport models, but also critical in estimating the safety environmental concentration threshold. In order to reduce the uncertainty caused by non-linear interactions among environmental factors, machine learning based models for predicting Kd were developed in this work based on literature datasets of nonionic pesticides including molecular descriptors, soil properties, and experimental settings. The equilibrium concentration (Ce) values were specifically included for the reason that a varied range of Kd corresponding to a given Ce occurred in a real environment. By transforming 466 isotherms reported in the literature, 2618 paired equilibrium concentrations of liquid-solid (Ce-Qe) data points were obtained. Results of SHapley Additive exPlanations revealed that soil organic carbon, Ce, and cavity formation were the most important. The distance-based applicability domain analysis was conducted for the 27 most frequently used pesticides with 15952 pieces of soil information from the HWSD-China dataset by setting three Ce scenarios (i.e., 10, 100, and 1000 µg L-1). It was revealed the groups of compounds showing log Kd < 0.06 and log Kd > 1.19 were composed mostly of those with log Kow of -0.800 and 5.50, respectively. When log Kd varied between 0.100 and 1.00, it was impacted by interactions among soil types, molecular descriptors, and Ce comprehensively, which accounted for 55% of the total 2618 calculations. It could be concluded that site-specific models developed in this work are necessary and practicable for the environmental risk assessment and management of nonionic organic compounds.

[Serum Lipid Levels and Their Prognostic Significance in Patients with Multiple Myeloma].

OBJECTIVE: To investigate the serum lipid levels and their prognostic significance in patients with multiple myeloma (MM). METHODS: A total of 87 newly diagnosed MM patients and 87 healthy controls in our hospital from January 2012 to April 2021 were selected. Serum lipid levels were compared between MM patients and healthy controls. The differences of serum lipid levels in patients among two groups of sex, age, hemoglobin (Hb), albumin (ALB), platelet (PLT), ß2-microglobulin (ß2-MG) and bone marrow plasma cell ratio (BMPC), different immune types, different ISS stages, before and after chemotherapy were analyzed. Univariate and COX multivariate regression analysis were used to analyze the influence of clinical parameters such as serum lipid indexes on prognosis of MM. RESULTS: The serum levels of total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), high density lipoprotein cholesterol (HDL-C), apolipoprotein A1 (Apo A1) and apolipoprotein B (Apo B) in MM patients were significantly lower than those in healthy controls (P<0.05). Anemia, low protein and low PLT in patients were related to low cholesterol. The levels of TC, LDL-C, HDL-C, Apo A1 and Apo B in patients with low Hb and ALB were significantly lower than those in patients with high Hb and ALB (P<0.05). The Apo B level of low PLT patients was significantly lower than that of high PLT patients (P<0.05). The levels of TC, LDL-C, HDL-C, Apo A1 and Apo B in patients with different immune types were significantly different, the above indexes of IgA type were significantly lower than IgG type(P<0.05), IgG type were significantly lower than light chain type(P<0.05), double clone type were significantly lower than light chain type (P<0.05). The levels of TC, LDL-C, and Apo B in patients with different ISS stages were significantly different, stage Ⅱ were lower than those of stage Ⅰ (P>0.05), stage Ⅲ were significantly lower than those of stage Ⅱ and stageⅠ(P<0.05). The levels of TC, TG, LDL-C, HDL-C, Apo A1 and Apo B in patients after chemotherapy were significantly higher than those before chemotherapy (P<0.05). Univariate analysis showed that Hb, PLT, ß2-MG, BMPC, LDL-C and Apo B affected the prognosis of MM. Multivariate analysis showed that BMPC and Apo B were independent factors affecting the prognosis of MM. CONCLUSION: The serum cholesterol level is decreased in MM patients, and hypocholesterolemia is related to the classification and staging of the disease. With the improvement of the disease, the serum cholesterol level is increased, and low serum Apo B level predicts a poor prognosis.

DNA walker-amplified signal-on electrochemical aptasensors for prostate-specific antigen coupling with two hairpin DNA probe-based hybridization reaction.

Electrochemical aptasensing systems have been developed for screening low-abundance disease-related proteins, but most of them involve multiple washings and multi-step separation during measurements, and thus are disadvantageous for routine use. In this work, an innovative and simple electrochemical aptasensing platform was designed for the voltammetric detection of prostate-specific antigen (PSA) in biological fluids without any washing and separation steps. This system mainly included a PSA-specific aptamer, a DNA walker and two hairpin DNA probes (i.e., thiolated hairpin DNA1 and ferrocene-labeled hairpin DNA2). Introduction of target PSA caused the release of the DNA walker from a partially complementary aptamer/DNA walker hybridization strand. The dissociated DNA walker opened the immobilized hairpin DNA1 on the electrode, accompanying subsequent displacement reaction with hairpin DNA2, thus resulting in the DNA walker step-by-step reaction with numerous hairpin DNA1 probes on the sensing interface. In this case, numerous ferrocene molecules were close to the electrode to amplify the voltammetric signal within the applied potentials. All reactions and electrochemical measurements including the target/aptamer reaction and hybridization chain reaction were implemented in the same detection cell. Under optimal conditions, the fabricated electrochemical aptasensor gave good voltammetric responses relative to the PSA concentrations within the range of 0.001-10 ng mL-1 at an ultralow detection limit of 0.67 pg mL-1. A good reproducibility with batch-to-batch errors was acquired for target PSA down to 11.5%. Non-target analytes did not interfere with the voltammetric signals of the electrochemical aptasensors. Meanwhile, 15 human serum specimens were measured with electrochemical aptasensors, and displayed well-matched results in comparison with the referenced human PSA enzyme-linked immunosorbant assay (ELISA) method. Significantly, this method provides a new horizon for the quantitative monitoring of low-concentration biomarkers or nucleic acids.

Mitigating cadmium contamination of rice soils supporting tobacco-rice rotation in southern China: Win-win or lose-lose?

The present study evaluates the sustainability of tobacco-rice rotation by reducing the phytoavailability of cadmium (Cd) to rice by combining large-scale field sampling and regional investigations in southern China. The rotation involves frequent tillage and liberal application of nitrogen and phosphorus fertilizers, which increases yields but lowers soil pH. As a result, manganese is lost from soil and, at the same time, more soil Cd is taken up by rice and tobacco. The tendency to overcompensate for the Mn loss is influenced by soil properties, crop type, and economics of cultivation. Based on the scenario analysis, this tendency and the Cd uptake risks were estimated. Dietary intake of 83.3% of rice grain produced on the rotation fields would have adverse health effects on local male nonsmokers. Besides the rice, Cd in local tobacco leaf may lead to an increase in the kidney Cd levels of local male smokers (21.5 cigarettes per day) by 16.2-fold at age 50. Field trials and model estimations indicated that for a Cd concentration below 0.2 mg dry weight kg-1 in rice grain, the critical pH value in rice soils was ~ 6.0, and that for amorphous Mn oxide at pH 4.5-6.0 was 120 mg kg-1.

Exposure to potentially toxic elements through the soil-tobacco-human pathway: causative factors and probabilistic model.

High concentrations of potentially toxic elements (PTEs) in tobacco leaves are possible from the soil contamination and would have adverse health risks on residents. A large-scale survey of 306 tobacco fields in southern China was conducted to investigate the accumulation of PTEs in tobacco leaves through the soil-tobacco-human pathway and the associated health risks for local smokers and passive smokers. Significant enrichment of As, Cd, Hg, and Pb was observed in the investigated tobacco fields, with industrial emissions and applied fertilizers as the major potential sources. Dynamic interactions between factors in the soil acidic labile pool showed site-specific effects on the uptake of PTEs by tobacco plants. It was 99.6% and 91.8% probable that exposure of local adult men smokers to Cd and As exceeded the permitted safety limits, respectively. The population of men smokers had a 20-fold higher Cd exposure risk than did passive smokers. A probability-based transfer model was developed to demonstrate that interactions between soil factors could affect the Cd exposure risk of men smokers of locally harvested tobacco. Optimizing the pH (>6.0) and organic matter content (>40 g kg-1) of tobacco-growing soils, and setting a safe tobacco consumption rate of 2.80 g dry weight per day would help protect 90.4% of men smokers from excessive risks of exposure to Cd.

Historical and future trends of cadmium in rice soils deduced from long-term regional investigation and probabilistic modeling.

When rice soils are contaminated by cadmium (Cd), the sources and timing of such contaminations need to be identified. In this study, we aimed to quantify the sources, history, and fate of Cd in the rice soils of southern China, by combining a near 10-year regional investigation, by developing a normalized positive matrix factorization algorithm, a Cd mass balance model, and probabilistic simulation. We simulated the historical contamination process of Cd in rice soils from 1991 to 2019 and the future changes from 2019 to 2069 under varying input parameters, as affected by different environmental management measures. Over the period of 1991-2019, the input flux of Cd through atmospheric deposition was estimated at 421 g ha-1, which contributed 52.1% of the total increments in soil Cd concentration. Over the next decade, a 25.6% probability is predicted that the Cd concentration of local rice soils would increase from the baseline to the upper level of soil threshold, despite the efforts of environmental regulators. Removing the rice straw from production fields, cleaning up the irrigation channels, and strengthening environmental regulations would take approximately 50 years (2019-2069) to ensure that 90% of soils were safe for rice cultivation.

Limestone dosage response of cadmium phytoavailability minimization in rice: A trade-off relationship between soil pH and amorphous manganese content.

Limestone shows great potential to reduce the production of cadmium (Cd)-contaminated rice in acidic paddy soils, but has generated uncertainty effects. We conducted batch sorption and greenhouse experiments to investigate optimal conditions of pH and amorphous manganese content (Mnox) in limestone treated-soil for suppressing the Cd uptake by rice plants. The adsorption/desorption behavior of Cd in a soil/limestone mixture was dominated by the composition and density of sorption sites, followed by sorption conditions, which were mainly influenced by soil pH and exchangeable Ca2+. Interactions among soil factors were influenced both by the limestone effects and plant responses. The Cd uptake of rice plants did not matched to the doses of limestone applied. The increase in pH and decrease in Mnox following higher dosages of limestone treatment might produce contradictory effects on rice Cd uptake. We proposed a trade-off model to demonstrate how did the interactions of soil pH and Mnox affect the rice Cd uptake. To minimize the accumulation of Cd in rice grain harvested from acidic paddy soils, limestone was applied at 0.25 % to achieve an optimal pH of 6.5 and a Mnox of 95 mg kg-1.

[Simulation Cadmium (Cd) Accumulation in Typical Paddy Soils in South China].

The simulation analysis of the migration path and soil accumulation trend of Cd in paddy soil systems could contribute to improved scientific and reasonable risk decision-making. In this study, based on a regional survey of environmental media in Youxian County, Hunan Province, a pollutant accumulation model (PAM) was built to predict the cumulative trend of Cd in paddy soils. Combined with Monte Carlo simulation, the PAM model was used to evaluate the effectiveness and sustainability of various remediation measures. Results showed that the probability of Cd accumulation in paddy soils in Youxian County exceeded that of the national soil environmental quality standard by 2-fold and was up to 82.1%, and the average accumulation rate reached 4.28 µg·(kg·a)-1 after 50 years of cultivation under current input pattern. Sensitivity analysis results showed that atmospheric deposition and rice uptake were the key processes affecting Cd accumulation in paddy soils. Results of a multi-scenario simulation showed that the comprehensive measures, such as reducing the straw returning, optimizing the layout of industrial and mining enterprises that reduce the atmospheric deposition of Cd, and cleaning irrigation water, could reduce the Cd accumulation in paddy soils by 43.7% and reduce the probability of light Cd pollution by 80.6% after 50 years, which would be an effective long-term measure to prevent and control Cd pollution risk in paddy soils.

Dynamic interactions between soil cadmium and zinc affect cadmium phytoavailability to rice and wheat: Regional investigation and risk modeling.

Characterizing the interactions between Cd and Zn with respect to the soil soluble Cd and crop Cd uptake allows the development of risk-based approaches to the performance of grain crops. By means of a three-year survey of 358 rice fields and 206 wheat fields across China, this study investigated the effect of Cd-Zn interactions on the phytoavailability of Cd to rice and wheat. The interactive nature between the Cd:Zn ratio and pH of soil affected crop Cd uptake, and the resulting grain Cd intake risk, were examined by the Free-Ion Activity-based model and probability analysis. In highly acidic rice soils (pH < 5.9), soil Zn had no effect on rice Cd uptake, whereas, under near-neutral conditions (pH > 5.9), a site-specific influence of soil Zn on grain Cd concentration was found. Soil Zn could inhibit Cd uptake and translocation by the plant in soil-wheat system when the soil Cd:Zn ratio decreased to 0.0083 and lower. Rice grain poses a significant health risk to local consumers due to its high Cd accumulation and its low Zn accumulation. In order to reduce the health risks from dietary Cd to local consumers, approximately 63.9% of the rice fields and 30.5% of the wheat fields require strategies ameliorating soil acidity in rice soils and increasing Zn concentrations in wheat soils.

[Application of Antinuclear Antibody and Antinuclear Antibody Spectrum in Lymphoma Treatment].

OBJECTIVE: To investigate the significance of antinuclear antibody and antinuclear antibody spectrum in the stage and prognosis of lymphoma patients. METHODS: 79 cases of lymphoma (lymphoma group) treated in the Second Affiliated Hospital of Fujian Medical University and 50 cases of healthy people (control group) were selected. Antinuclear antibodies (ANA) were detected by indirect innmunofluorescence and ANA spectrums were detected by linear Western blot, the expression level of ANA and ANA spectrum in the two groups were analyzed. The lymphoma group was divided into the positive and the negative group according to ANA level, the levels of lactate dehydrogenase (LDH), white blood cell (WBC), disease type, stage and prognosis of the two groups were compared. RESULTS: In the lymphoma group, the positive rate of ANA was 48.1%, while the positive rate was 8.0% in the health control group, both of them showed statistically significant (χ2=22.42, P＜0.05). ANA fluorescence karyotype in lymphoma group was mainly speckle type. In the Lymphoma group, the positive rate of ANA spectrum was 29.1%, while the positive rate in the control group was 4.0%, both of them showed statistically significant (χ2=12.36, P＜0.05). The target antigen distribution of ANA spectrum in the lymphoma group was relatively complex, mainly RO52 and SSA, while that in the control group was simple. The positive rate of ANA in lymphoma patients showed increased with age, the titer was mainly 1∶100 low titer positive, the positive rate of ANA in female patients was higher than that in male patients; The average count±standard deviation of LDH and WBC in the ANA positive and negative group were (253.67±255.85) U/L, (218.18±208.34) U/L, (6.34±3.31)×109/L and (6.81±3.91)×109/L respectively, which showed no statistical significance between the two groups (t=0.59 P＞0.05; t=0.57 P＞0.05); B-cell lymphoma was the main disease in both groups, which accounted for 81.6% (31/38) and 68.3% (28/41) respectively; while in B-cell lymphoma, diffuse large B-cell lymphoma was the main lymphoma. For the patients with B-cell lymphoma, the patients at stage IV in ANA positive group was 58.1% (18/31), while that in the ANA negative group was 28.6% (8 / 28), and both of them showed statistically significant (χ2=5.19, P＜0.05). Follow-up showed that the survival rate of the patients in ANA negative group was higher than that in ANA positive group, which showed statistically significant difference (P＜0.05). CONCLUSION: The postive rate of antinuclear antibody and antinuclear antibody spectrum are higher in lymphoma patients, which have considerable significance for the stage and prognosis of lymphoma treatment.

Inconsistent effects of limestone on rice cadmium uptake: Results from multi-scale field trials and large-scale investigation.

Adding limestone into acidic paddy soils might reduce cadmium (Cd) accumulation in rice plants and the harvested grains but with inconsistent results in the field practice. We conducted three experiments of different field scales, including small-plots, multi-location trial, and large-scale field samplings of rice grown in a major production region of southern China, to investigate whether liming could sustainably limit the Cd phytoavailability to rice. Forty-eight physical, chemical, and biological attributes associated with paired soils and plants were collectively analyzed. Rice Cd uptake was significantly reduced when moderate dosage (2.25-3 t ha-1) of liming was present in the soils. The limes decreased rice Cd uptake by reducing the Cd concentrations of soil solution phase and regulating Ca2+ and Cd2+ competitions for absorption sites at root surfaces. Soil Zn hardly any effect on rice Cd uptake. Rice Cd uptake was suppressed at the higher rates of liming (4.5-9 t ha-1) due to the heavy loss of soil labile Mn. The tendencies of over compensating were soil-, plant-, and climate-dependent and were estimated by a transfer function and the risks were characterized using probabilistic analysis. The sustainable doses of limestone that reduced grain Cd accumulation, but did not compromise yield, or disrupt the rice rhizosphere was 3 t ha-1 annually incorporated two weeks before the seedlings were transplanted.

Evaluation of combined toxicity of Siduron and cadmium on earthworm (Eisenia fetida) using Biomarker Response Index.

Agrochemicals and heavy metals are widespread contaminants in urban soil and could co-exist as mixture, which could cause unexpected risk to terrestrial organism. To assess the joint effect of herbicide Siduron and Cd, a battery of sub-lethal biomarkers was studied using earthworm ecotoxicological assay. Most selected biomarkers appeared significant but complicated responses with the increasing concentration of contaminants after 28-day exposure. In order to quantify the overall effect of the mixture contaminants, Biomarker Response Index (BRI) was used to integrate the multiple responses. Concentration Addition Index (CAI) and Effect Addition Index (EAI) were introduced to assess types of joint effect. Results showed significantly dose-effect responses between BRI and contaminant exposure concentrations. Integrated toxicity increased obviously under joint treatments of Siduron and Cd compared to their individual treatments. According to CAI, a clear antagonism was observed at relatively lower effects and gradually transformed to slight synergism with an increase of effects, while EAI showed the joint effect of addition at the whole range of effect levels. Thus, compared to the simple analysis of those complicated responses, BRI is an effective method to determine the integrated toxicity of mixture and its combination with joint effect indices (CAI and EAI) provides more worthy risk assessment on toxicity interaction among compounds.

Manganese, Zinc, and pH Affect Cadmium Accumulation in Rice Grain under Field Conditions in Southern China.

Very little has been reported on the effects of pH, Zn, and Mn on Cd uptake in rice ( L.) and their levels under field conditions. Rice accumulates a high concentration of Cd in acid soils, even at low soil Cd levels. Lime (CaO) was spread at 1200 kg ha on the topsoil of a rice field during the tillering stage. Effects of liming on rice Cd, soil pH, and amorphous Mn (MnO-AM) were then investigated. Slight increases in pH from 5.17 to 5.45 and MnO-AM from 66.3 to 82.1 mg kg were observed after liming. The proportion of rice samples with a Cd concentration greater than the Chinese rice Cd standard (0.2 mg kg dry wt. in grain) decreased by ∼15%. The pH, which varied from 4.8 to 5.8, did not significantly affect rice Cd, whereas soil Cd and Zn had a significantly positive effect, together accounting for ∼14% of the variance. Soil Mn had significantly negative effects on rice Cd, accounting for >18% of the variance. For a Cd concentration <0.2 mg kg dry wt. in rice grain, the critical pH value in paddy soil was ∼5.7, and that for Mn at pH 4.8 to 5.8 was ∼300 mg kg. Our findings showed that Cd concentration in rice grain in an acid paddy soil increased with an increase of Zn and a decrease of Mn when these metals were at sufficient levels.

Assessing cadmium exposure risks of vegetables with plant uptake factor and soil property.

Plant uptake factors (PUFs) are of great importance in human cadmium (Cd) exposure risk assessment while it has been often treated in a generic way. We collected 1077 pairs of vegetable-soil samples from production fields to characterize Cd PUFs and demonstrated their utility in assessing Cd exposure risks to consumers of locally grown vegetables. The Cd PUFs varied with plant species and pH and organic matter content of soils. Once normalized PUFs against soil parameters, the PUFs distributions were log-normal in nature. In this manner, the PUFs were represented by definable probability distributions instead of a deterministic figure. The Cd exposure risks were then assessed using the normalized PUF based on the Monte Carlo simulation algorithm. Factors affecting the extent of Cd exposures were isolated through sensitivity analyses. Normalized PUF would illustrate the outcomes for uncontaminated and slightly contaminated soils. Among the vegetables, lettuce was potentially hazardous for residents due to its high Cd accumulation but low Zn concentration. To protect 95% of the lettuce production from causing excessive Cd exposure risks, pH of soils needed to be 5.9 and above.

Cadmium Accumulation Risk in Vegetables and Rice in Southern China: Insights from Solid-Solution Partitioning and Plant Uptake Factor.

Solid-solution partitioning coefficient (Kd) and plant uptake factor (PUF) largely determine the solubility and mobility of soil Cd to food crops. A four-year regional investigation was conducted in contaminated vegetable and paddy fields of southern China to quantify the variability in Kd and PUF. The distributions of Kd and PUF characterizing transfers of Cd from soil to vegetable and rice are probabilistic in nature. Dynamics in soil pH and soil Zn greatly affected the variations of Kd. In addition to soil pH, soil organic matter had a major influence on PUF variations in vegetables. Heavy leaching of soil Mn caused a higher Cd accumulation in rice grain. Dietary ingestion of 85.5% of the locally produced vegetable and rice would have adverse health risks, with rice consumption contributing 97.2% of the risk. A probabilistic risk analysis based on derived transfer function reveals the amorphous Mn oxide content exerts a major influence on Cd accumulation in rice in pH conditions below 5.5. Risk estimation and field experiments show that to limit the Cd concentration in rice grains, soil management strategies should include improving the pH and soil Mn concentration to around 6.0 and 345 mg kg-1, respectively. Our work illustrates that re-establishing a balance in trace elements in soils' labile pool provides an effective risk-based approach for safer crop practices.

[Variation Characteristics of Vegetables Cadmium Uptake Factors and Its Relations to Environmental Factors].

The consumption of vegetables is a probable cause of Cd exposure in several world areas including China.In this study,we selected the prefecture of Youxian,southern China,as a case to analyze the influences of various environmental factors on Cd accumulation in vegetables based on a large scale agricultural and climatologically survey and collection of 585 irrigation water and 625 paired soil-vegetables samples.The results showed the concentration of Cd differed greatly in the irrigation water,soil and vegetables.The average daily dose for the adult populations consumed vegetables cropping in affected areas was slightly above the tolerable daily intake level,suggesting a potential health risk.The vegetables Cd uptake factor followed the natural lognormal distribution,and had a 10 percentile probability of higher than 1.The PUF values exhibited comparable results and appeared to define a reasonable and consistent Cd risk assessment.Many environmental variables (soil pH,soil organic matter,cation-exchange capacity,rainfall,water pH,and nitrogenous fertilizer usage) exhibited significant correlations with the concentrations of Cd in the soil-vegetable system.The canonical corresponding analysis and path model analysis found that soil pH and soil organic matter (SOM) had major direct effects on PUF.The close correlations between rainfall,water pH,nitrogen fertilizer usage and PUF were mainly resuled from the direct effect of soil pH and SOM.The high field-moisture capacity in the study area generated a rapid acidification causing the migration of Cd to weaker bounding sites thus promoting the vegetables uptake.The excessive application of nitrogen fertilizers led to a substantial loss of SOM and worsening of soil acidification ultimately causing increasing Cd accumulation in vegetables.Considering that the soil pH and SOM in the study area were maintained at a low level,the accumulation risk of Cd in soil-vegetable system needs to be addressed.The influence of environmental factors on vegetables accumulating Cd needs to be fully considered for better and safer vegetables production.

Evaluation of combined noxious effects of siduron and cadmium on the earthworm Eisenia fetida.

Environmental contaminants do not often occur as individual chemicals but rather in complex mixtures whose joint effects can create a strong toxicity to surrounding organisms. To determine the combined harmful effects of siduron (herbicide) and cadmium (heavy metal) toward Eisenia fetida earthworms, samples of worm's coelomocytes were subjected to siduron and cadmium (Cd) at sublethal concentrations (lower than LC50)-siduron 0, 0.8, 2.4, and 7.2 µg cm-2 Cd 0, 0.4, 0.8, and 1.6 µg cm-2 in filter paper contact assay, both as individual compounds and combinations. The CI-isobologram model was utilized to reveal the types of toxicological interactions between siduron and cadmium in inducing DNA damage toward earthworms. The results indicated that tail DNA percentage (TDNA %) at individual siduron and cadmium concentrations (with the exception of the lowest concentration of Cd 0.04 µgcm -2) were highly significant compared to those of the control (p < 0.01). Tail moments (TM) at individual Cd concentrations (0.8 and 1.6 µg cm -2) were highly significant compared to those of the control (p < 0.05), while the increase of TM for individual siduron was only significant (p < 0.05) at 7.2 µg cm -2 which is the highest dose/concentration of siduron used in this study. The combinations of siduron and Cd indicated a significant synergism (CI < 1) at the lower effect levels and a significant antagonism (CI > 1) at the higher effect levels. The synergistic effect for a particular combination of chemicals suggests that there might be a possible risk connected to the coincidence of these chemicals.

Regional accumulation characteristics of cadmium in vegetables: Influencing factors, transfer model and indication of soil threshold content.

A regional investigation in the Youxian prefecture, southern China, was conducted to analyze the impact of environmental factors including soil properties and irrigation in conjunction with the use of fertilizers on the accumulation of Cd in vegetables. The Cd transfer potential from soil to vegetable was provided by the plant uptake factor (PUF), which varied by three orders of magnitude and was described by a Gaussian distribution model. The soil pH, content of soil organic matter (SOM), concentrations of Zn in the soil, pH of irrigation water and nitrogenous fertilizers contributed significantly to the PUF variations. A path model analysis, however, revealed the principal control of the PUF values resulted from the soil pH, soil Zn concentrations and SOM. Transfer functions were developed using the total soil Cd concentrations, soil pH, and SOM. They explained 56% of the variance for all samples irrespective of the vegetable genotypes. The transfer functions predicted the probability of exceeding China food safety standard concentrations for Cd in four major consumable vegetables under different soil conditions. Poor production practices in the study area involved usage of soil with pH values ≤ 5.5, especially for the cultivation of Raphanus sativus L., even with soil Cd concentrations below the China soil quality standard. We found the soil standard Cd concentrations for cultivating vegetables was not strict enough for strongly acidic (pH ≤ 5.5) and SOM-poor (SOM ≤ 10 g kg-1) soils present in southern China. It is thus necessary to address the effect of environmental variables to generate a suitable Cd threshold for cultivated soils.