Cadmium pollution not only affects plant growth, but also threats to human health, which has been the study hotspot of domestic and foreign. This paper reviewed the effect on Cadmium to plant growth, the mechanism of uptake, transport and resistance of plant to Cadmium. And some new ideas for future research directions are put forward.

Heavy metal pollution has been one of the main factors affecting the quality of food in China. The pollution limit standards of food were made to ensure the quality safety of food. In this paper, maximum limit standards of heavy metals in major foods, the pollution situation and the conventional detection methods of heavy metals in China were introduced. Then, rapid detection technologies of heavy metalsincluding reagent colorimetric, rapid detection strip, electrochemical technology and enzymatic inhibition were reviewed. At last, countermeasures including strictly controlling sources of heavy metals and strengthening management; improving the research of the rapid detection technologies and methods, enhancing the supervision of government management departments and introducing the food risk assessment system of heavy metals were proposed to provide references for detection, supervise and management of heavy metals in food in China.

【Objective】 Bacterial wilt of plants, caused by Ralstonia solanacearum , is a major soil-borne disease around the world. As an important bactericide to control bacterial diseases such as bacterial wilt, the widespread use of copper-based bactericides has led to the emergence of copper-resistant strains in a variety of plant pathogenic bacterial population. The copper-resistant coding gene copA , homologous with Pseudomonas syringae , was carried on the megaplasmid of R. solanacearum Po82 strain. The objective of this study is to investigate the biological function of copA in copper resistance and pathogenicity of Po82 strain.【Method】The phylogenetic relationship of the copper-resistant gene copA in different strains of R. solanacearum and other phytobacterial strains was analyzed based on neighbor-joining method using MEGA6.0 for constructing the phylogenetic tree of copA . By means of reverse genetics strategy, using the methods of gene homologous recombination and electroporation, copA gene deletion and complementary strains of Po82 were constructed. Copper minimal inhibition concentration (MIC) test, RT-qPCR, Biolog chip analysis, pathogenicity test and other basic biological methods were employed to clarify the relationship between copA and biological characteristics such as response to copper stress, metabolic activity, pathogenicity, and motility of R. solanacearum. 【Result】The results of homology analysis showed that the copA existed widely in the bacterial population, and the copA of R. solanacearum was most closely related to Cupriavidus metallidurans , but far genetic relationship with Xanthomonas oryzae , P. syringae and Escherichia coli . RT-qPCR analysis showed that the expression of copA was induced by copper. The expression of copA increased with the increase of CuSO₄ concentration. The expression level of copA was the highest when the CuSO₄ concentration was 1.0 mmol·L ^-1. By MIC analysis, the result showed that the sensitivity of the copA deletion strain to copper was significantly increased. The MIC value of copA deletion strain was 0.8 mmol·L ^-1, which decreased by 33.3% compared with that of wild-type strain (1.2 mmol·L ^-1). The complementary strain restored copper resistance. The results indicated that copA played an important role in copper resistance of R. solanacearum . Compared with wild-type strain, the logarithmic growth rate of copA gene deletion strain decreased in both NA medium and NA medium containing 0.6 mmol·L ^-1 CuSO₄, indicating that copA was related to the growth rate of R. solanacearum . The absence of copA resulted in a decrease in the pathogenicity of R. solanacearum . On the 10th day of inoculation, the disease index of the copA gene deletion strain decreased by 11.7% compared with that of the wild-type strain Po82. The absence of copA resulted in a reduction of metabolic utilization rate of carbon sources such as α -D-glucose, D-trehalose and nitrogen sources such as L-alanine and glucuronide. Compared with wild-type strain Po82, the expression level of hrpB , hrpG and ripX genes, which are important components of the type Ⅲ secretion system, was also significantly down-regulated in copA gene deletion strain. 【Conclusion】 The copper-resistant gene copA plays an important role in copper stress response and pathogenicity of R. solanacearum . The results provide a theoretical basis for further analysis of copper resistance mechanism and the control of copper-resistant strains.

In order to research the difference of Cd, Zn and As accumulation in different hybrid rice cultivars, 30 different hybrid rice cultivars were cultivated in a heavy metal and arsenic polluted paddy field which located in a mine zone of southern Hunan Province. The results showed that: there were certain differences of accumulation Cd, Zn and inorganic As between different genotypes of hybrid rice cultivars. The brown rice contents of Cd, Zn and As in 30 different hybrid rice cultivars were 0.28-0.83, 24.13-34.16, 0.45-0.77 mg/kg, respectively. Cd accumulation in brown rice of different genotypes of hybrid rice cultivars has significant difference, while Zn and As accumulation in brown rice is small differences. The significant difference of Cd content in brown rice exist between the two-lined hybrid rice and three-lined hybrid rice (P<0.05), and the differences of Zn and As contents in brown rice was not significant. Therefore, depending on differences of heavy metals accumulation in different hybrid rice cultivars, it indicated that the selection the pollution-safe cultivars were possible.

Soil pollution has become an important problem affecting crop production and harming human health, it should be studied and solved urgently. The objectives are to provide theoretical support for the reduction of Cd, As, Pb, Cu, Zn bioavailability, develop techniques of heavy metal abatement in polluted soils in wheat production, and lay a foundation for field heavy metal pollution monitoring and comprehensive management. The single element pollution was used in this study. The effects of Cd, As, Pb, Cu and Zn stress on the growth and physiological indexes of wheat were studied by indoor hydroponic experiment and field trial. The results showed that low concentration of heavy metals promoted the germination of wheat seeds to a certain extent, while the high concentration of heavy metals inhibited the seed germination. In different treatments, the total aboveground dry matter content of wheat showed a“slow-fast-slow”growth trend. The plant height, spikelet number, sterile spikelet number and ear number decreased, the thousand seed weight increased, and the economic coefficient decreased, which resulted in the reduction of yield ultimately.

To explore the molecular mechanism of cadmium tolerance of plant and provide a theoretical basis for plant protein transporting heavy metals, this article summarizes the structure and function of transport protein CAXs (cation/H⁺ exchangers) and HMAs (Heavy metal ATPase), and their effects on plant growth, as well as the detoxification mechanism of heavy metals under synergy. CAXs play an important role in improving phytoremediation potential and strengthening plant nutrition, which is mainly related to plants transport divalent cations into the membrane, also determine the concentration of Ca²⁺ in plants, and participate in transportation and detoxicification of heavy metal ions. The operation of CAXs is related to the electrochemical H⁺ gradient generated by plasma membrane and vacuolar membrane of HMAs across the plasma membrane of the cell, which provides essential energy support for CAXs transportation. However, the synergistic mechanism of CAXs and HMAs needs further research. It is suggested that the study of CAXs and HMAs activities and the interrelationship between CAXs and HMAs could provide a basis for future plant genetic engineering for remediation heavy metal pollution soil.

This study aims at investigating the impact of different extraction methods on the properties of dissolved organic matter (DOM) derived from biochar. Biochar was used as material, DOM was extracted with various extracting agents and extraction patterns, and the carbon content and chemical composition of the extracts were analyzed. The results showed that the DOC content of alkali extract in low-temperature biochar was relatively high (15.6-40.0 g/kg), so was the DOC content of salt extract in high-temperature biochar (0.27-7.04 g/kg). The chemical composition of DOM in the acid extract remained relatively simple, showing that SUVA₂₅₄ and SUVA₂₈₀ were low. A higher proportion of hydrophilic DOM was found in the acid extract from cornstalk-derived biochar (44.6%-73.6%) compared with that in the water and alkali extracts (11.0%-53.2% and 0.30%-31.4%), respectively (P<0.05). Correspondingly, the chemical composition of DOM in the alkali extract was relatively complex, showing that SUVA₂₅₄ and SUVA₂₈₀ were high. A higher proportion of hydrophobic DOM was found in the alkali extract from cornstalk-derived biochar (68.6%-99.7%) compared with that in the acid and salt extracts (26.4%-55.4% and 0%-46.9%), respectively (P<0.05). The study indicates that extracting agents have certain significance in biochar DOM extraction, while extraction patterns exhibit a minor effect on the properties of biochar DOM. It could provide reference for selecting biochar DOM extraction method.

In order to master the status and problems of heavy metal pollution in the river for studying deeply it, research aspects and contents of heavy metal pollution in the river were carefully reviewed and analyzed in the past 20 years. It was indicated that the research of river heavy metal pollution had a wide spatial distribution and maturity determination method, but each measurement method had many defects. Furthermore, governance of river heavy metal pollution had not proven effective method. It was recommended that green and economy bioremediation technology should be used to restore contaminated water environment.

To study the rivaty of the Yupingfeng Power to the Cadmium toxicosis on the liver in chicken, and the 150 30-day cocks were divided into 3 groups: the control group (A: feeding on a basal diet), the Cadmium group(B: feeding on a basal diet+150 CdCl2 150 mg/kg), the Yupingfeng power and the Cadmium group (C: feeding on a basal diet+150 CdCl2 150 mg/kg+1 mL the Yupingfeng power days), and all of them were allowed to feed on freely. The 10 cock of every group were killed after 15, 30, 45, 60 days, then the targets were detected in livers tissue. The results showed that as time of the Cadmium toxicosis prolonging, the activity of GSH-Px and SOD reduced in B group and C group, and the MDA production increased; The difference between the test group and the control group was significant (P<0.05) or significantly increased (P<0.01), and each index of C group was between A group and B group. The conclusion was that the Yupingfeng powder could reduced the Cadmium toxicosis effect, and rival the Cadmium toxicosis.

With the rapid development of agriculture and industry, soil contamination has become a very serious environmental problem facing today, while the contamination of soil by heavy metals is one of the important parts. Physical remediation and chemical remediation and bioremediation are the important methods for solving heavy metal pollution in soil, combined remediation is raised as the research continues. The sources and current situation of soil heavy metal contamination in our country and its repair mechanism, advantages and disadvantages, the standards and evaluation methods after remediation and research progresses both in domestic and abroad are discussed carefully in the text, on this basis, the author comes up with some issues in the future research and looks forward to the future, in order to have contributions to subsequent researches.

With the increase of the industrialization level, some heavy metal pollutants enter soil through different kinds of forms and channels with the expanding scope and scale of human social activities. Because heavy metal pollutants have features like being difficult to remove and to degrade and very harmful, they could cause serious pollution to soil. Human health problems brought by heavy metal pollution in soil have become more and more prominent, therefore, research on soil heavy metal treatment is extremely urgent. Clarifying the types, sources and excessive hazards of heavy metal pollutants in soil, as well as pollution control methods and mechanisms and their advantages and disadvantages, could play a promoting role in carrying out soil heavy metal control and management. Through literature research, the authors elaborated the problems in the heavy metal pollution control and discussed its development prospect, aiming to provide reference for related scientific research.

In order to apply the new method in the evaluation of soil environmental quality, which can overcome the disadvantages of the national environmental quality standards (GB 15618-1995, China) and Nemerow comprehensive pollution index. The method is based on the BP neural network model combined GIS technology. The author analyzed the spatial distribution of soil heavy metal pollution in Baotou City of China. The concentrations of 8 heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were measured in 221 plough layer (0-20 cm) soil sampling in Baotou. The field investigation of 221 topsoil samples were statistically analyzed to show that the study areas were mainly Pb, Zn pollution. It was important to consider the study area geographical features. So the author made the learning samples of BP neural network based on the statistical results and data specificity in study areas. The BP soil environmental quality evaluation model was designed by using the pollution value. According to the evaluation results obtained by the Kriging interpolation method, the author drew Baotou soil environmental quality thematic charts, also the spatial characteristics of Baotou soil environment analysis was included. It was found that the enrichment of heavy metals in topsoil was very obvious in industrial areas and regions near both sides of the Kundulun River. The results indicated that, according to sampling statistics information, the method using BP neural network model could effectively establish special research area soil through non-linear mapping relation between heavy metal contaminate and environmental quality.

Abiotic stressors, such as water, saline-alkali, temperature and heavy metals, stress the growth and development of tobacco, and current research has found that exogenous substances play a very important role in tobacco stress mitigation. This paper summarizes the adverse effects of abiotic stress on tobacco growth, and the pathways of the action of exogenous substances in alleviating abiotic stress, analyzes the optimal concentration of exogenous substance application, and points out the possible adverse effects of exogenous substance application on tobacco. It also points out that the effect of multiple exogenous substances in combination is better than the effect of single exogenous substance, and discusses future prospects of tobacco abiotic adversity research, aiming to provide a theoretical basis for the exploration and application of new exogenous substances in tobacco cultivation and the elucidation of their regulatory mechanisms to mitigate the abiotic adversity.

In order to understand the current situation of heavy metal pollution in greenbelt soil of Huaihua City, this research studied the quantitative characteristics of heavy metal pollution in different regions and different types of greenbelt soil of Huaihua City, by using INNOV-X soil heavy metal measurement instrument and the method of single factor pollution index and the synthesis pollution index. Results showed that: both the individual pollution indexes of Cr and As element in the three regional greenbelt where located in city center, Yingfeng area, Tuoyuan area were greater than 1, manifesting as light pollution. The synthesis pollution index of three regional greenbelts was greater than 1, also manifesting as light pollution. And the changes showed certain regularity, the pollution degree had the trend of increasing gradually from suburbs to city center. The individual pollution indexes of Cr, As and Cu element in the road greenbelt, the public greenbelt of Huaihua City were all greater than 1, manifesting as light pollution or moderate pollution. Except for the productive greenbelt, the synthesis pollution indexes of other greenbelt types were greater than 1, manifesting as light pollution. Different greenbelt types showed different levels of pollution, road greenbelt > public greenbelt > accessory greenbelt > productive greenbelt. In view of the above situation, adopting preventive and control measures to control the heavy metal pollution in greenbelt soil of Huaihua City is very important to the construction of ecological livable city.

The purpose of this study was to comprehensively understand the quality of Foeniculi fructus from various production origins in China. 21 batches of samples were collected from seven major production origins, and the volatile oil, trans anisole, Hg, Cd, As, Cu, Pb and 9 kinds of organochlorine pesticide residues were evaluated in accordance with the People's Republic of China Pharmacopoeia. The study showed that the quality of F. fructus was good, the volatile oil and trans anisole indexes of F. fructus from all production origins were higher than the pharmacopoeia standard requirements. The content of Hg, Cd, As, Cu, Pb heavy metals were low and the residues of nine organochlorine pesticides were zero, which meant that all samples of F. fructus met the safety requirements. The content of volatile oil and trans anisole was the highest in Yumen of Gansu Province, while the content of cumin in Minqin, Haiyuan, Jingtai of Gansu Province, Shuozhou of Shanxi Province and Inner Mongolia was little different. The content of volatile oil of cumin in Minqin was higher than that in other producing areas, and the content of volatile oil in Jinta of Gansu Province was the lowest.

In order to evaluate the environmental quality of heavy metal Pb in the surface soil and stream sediment in wastewater irrigation area of Baotou southern suburbs (WIBS). Samples were collected by using linear, profile-based and quincunx to determine the content of Pb in stream sediment and soil in different locations and regions, to analyze effects of Pb on the ecological environment, and the soil environmental quality in the research area. The results showed that the content of soil Pb in the WIBS was larger than 1.25 times of the farmland in groundwater irrigation in Baotou northern suburbs. The highest content of Pb in the main inundation sewage drainage of the research area was 565.40 mg/kg, and the highest content of soil Pb in the WIBS was 22.12 mg/kg, the average value was 19.46 mg/kg, the maximum monomial pollution index of Pb growing crop and vegetables were 0.28 and 0.44, and pollution index (Pi) was less than 0.7. Composite index of potential ecological risk was 41.18 and composite index (Ei) was less than 90. It indicated that the environmental quality of heavy metal Pb in the WIBS was lower than pollution levels and potential ecological risk degree belonged to mild. Heavy metals Pb was accumulated in the WIBS as human activities, people should pay attention to lead pollution with potential ecological risk.

Phytoremediation is a novel, solar-driven, in-situ and cost-effective technology for the remediation of heavy metal contaminated environments, and become a hot topic in recent years which attracts scholars. But low heavy metal bioavailability and small biomass of hyperaccumulators limits application of phytoremediation technology. Finding natural environment-friendly clelator and plant remediation system with high extraction efficiency will help break through the bottlenecks of phytoremediation. On the basis of analyzing and summing up the relative literatures, and combining the theory of ecological niche and phytoremediation, the author discussed remediation ability of woody, weed plant in heavy metal contaminated soil, and analyzed the feasibility of woody-weed plant joint remediation, presented a new development direction of phytoremediation.

In order to study the salicylic acid to alleviate the toxic effects of cadmium on the ryegrass (Lolium perenne L.), a pot experiment was used to determinate of the changes of physiological indicators of the ryegrass under heavy metal cadmium stress spraying exogenous salicylic acid. The results showed that the spraying of 100, 200 and 300 mg/L of the concentration of salicylic acid on the ryegrass under Cd stress had no significant effect at the chlorophyll content, but could increase the contents of the proline and the soluble sugar, the important osmotic adjustment substances, in the ryegrass leaves, enhancement effect of 200 mg/L concentration of salicylic acid on proline content was significantly higher than that of the other concentrations; spraying salicylic acid could significantly increase the activity of SOD, POD, CAT and other antioxidant enzyme, reduce the electrolyte permeability and MDA content in various concentrations. The significant difference between the level difference was not exist, 200 and 300 mg/L concentrations had greater role. The determination of physiological index could state that salicylic acid relieved the toxic effects of cadmium on ryegrass.

With the acceleration of urbanization and industrialization, soil heavy metal pollution has been an environmental problem with common concern at home and abroad, and has seriously threatened the stability of the earth’s ecosystem and the safety of human life. Therefore, it is urgent to solve such a problem. Based on the introduction of the current situation of soil heavy metal pollution, the paper summarized the effects of soil heavy metals on plants, introduced the phytoremediation mechanism of soil heavy metals and the advances in the research of soil heavy metal phytoremediation. The paper put forward the research orientation in the future: hyperaccumulators should be selected to lay a foundation for the research on the phytoremediation mechanism of soil heavy metal pollution; the effects of microorganisms on phytoremediation should be the research focus; the research on woody plants should be strengthened, especially the research on the ability of indigenous plants with strong tolerance to soil heavy metal pollution; and the research on the safe recovery and rational utilization of hyperaccumulators after their withering should be conducted.

In order to detect sources of arsenic in the Spirulina platensis power from the ordos alkali lake in Inner Mongolia, Arsenic content of culturing materials, nutrient solution and algal power in the period of initial cultivation and normal cultivation for Spirulina platensis was studied. The results showed that the water for culturing Spirulina platensis and NaHCO3 providing the arsenic into the nutrient solution in the period of no culturing for Spirulina platensis, the arsenic content correspondingly keeps in a stable state not only in the period of initial cultivation and normal cultivation and long terms of cultivation, the arsenic content would cut down by cleaning the algal power auxiliarily with distilled water.

In order to study the microbial application of remediation technology in heavy metal pollution, the mechanism of microbial remediation method used for heavy metal pollution were reviewed, and the effects of different microorganisms (bacteria, fungi, algae) applied for heavy metal pollution were introduced. The development of microbial remediation on heavy metal pollution was prospected; there were still deficiencies in industrial applications which needed further study in the future.

There is a deep relationship between phosphorus fertilizer apply and environmental quality. This article discusses these following factors. Over phosphorus fertilizer apply accelerates agricultural non-point pollution which improves the risk of eutrophication of surface waters. The heavy metal in phosphorus fertilizer has influence on soil environment and products quality which affect human health.

In order to investigate the restoration effect of ramie on heavy metals contaminated soils under different repair measures, a pot experiment was conducted to observe the effect of three amendment substances (organic compound fertilizer, lime and sepiolite) on biomass, chlorophyll and heavy metals cadmium and lead accumulation characteristics of ramie (Boehmeria nivea) in soils contaminated with cadmium and lead. The results showed that different amendment substances and their combination treatment could increase the chlorophyll content and a/b ratio, improve the photosynthesis, and result in a significant increase in biomass. The combination treatment of three amendments accumulated the maximum biomass, organic fertilizer and its combination with sepiolite slightly times. The accumulation levels of cadmium, lead in roots and shoots in ramie significantly reduced under different applications. Single application of lime and sepiolite processing reduced largely, both combination treatments lesser decreased, declined in at least of single organic fertilizer processing. Different modifiers could promote the raise of ramie transfer coefficient, but the increase in amplitude was not obvious. In general, single application of organic fertilizer and its combination with lime and sepiolite had better results, which could effectively reduce the content of cadmium and lead in contaminated soil, improve soil physical and chemical properties, promote the growth of ramie, and have an ideal effect of plant restoration.

Since the 1990s, soil heavy metal pollution has become increasingly serious, microbial remediation as a new soil heavy metal pollution remediation technology has become a research hotspot in soil remediation. This article mainly described current development trend of soil heavy metal pollution and the technical problems existing in the remediation process, and focused on the mechanism of microbial remediation of heavy metal pollution in farmland soil, as well as the application and implementation effects of microbes combined with passivators and plants in the remediation of heavy metal polluted farmland soil. At the same time, this article put forward relevant suggestions on formulating industrial standards and improving the microbial remediation technologies.

The differences of the contents of heavy metals are obvious in the different vegetable kinds and breeds. The vegetable breeds which average contents of heavy metal are high have three-coloured amaranth, asparagus lettuce, raw vegetable, onion; which variable coefficient of heavy metals are big have cabbage, hot pepper, onion. The contents of many heavy metals in leaf vegetable are bigger than in fruit and vegetable. The correlation analysis in the different vegetable kinds shows that the correlation degree is bigger in leaf vegetable than in fruit and vegetable. The correlation analysis of heavy metals displays the correlation degree of the different vegetable breeds is bigger in asparagus lettuce than in cabbage than in kidney bean than in onion than in hot pepper than in raw vegetable than in three-coloured amaranth. The classify analysis of heavy metals shows that the coordination and formal of heavy metals are large differences in the different vegetable breeds, and the contents of heavy metals of same vegetable breeds have similarity. We find that the main vegetable breeds that beyond standards are leaf vegetable, and the areas that beyond standards main are in the outskirts of a town, and the main heavy metals that beyond standards are Pb Cd.

Central-south China is distinguished by the considerable numbers and areas of non-ferrous metal smelting sites that have polluted the soils both within and surrounding the sites. This brings serious risks to the local environment and needs to be controlled urgently. To explore the pollution characteristics of the smelting sites and the surrounding soil in central-south China and the main effective stabilization and remediation technologies, we summarized the distribution of nonferrous metal smelting sites in Hunan, Hubei, Jiangxi and Anhui, and their pollution status. The pollution characteristics included large pollution area, mainly compound pollution, diversified pollution ways, different pollution levels and high heavy metal activity. The advances of stabilized materials used in remediation were expounded from two aspects: stabilization mechanism and material type. Finally, we discussed future research on the development of composite stabilization materials with high-performance, sustainability, wide adaptability and environmental value, aiming to provide support for the stabilized remediation of soil heavy metal pollution in nonferrous metal smelting sites and surrounding soil in central-south China.

Arsenic is a metalloid with different inorganic and organic forms. Arsenic widely exists in the environment and comes from both natural occurrence and anthropogenic activity. Arsenic and inorganic arsenic compounds are carcinogenic to humans and are classified as Group 1 by International Agency for Research on Cancer (IARC). It is proved that food and water are the major contributors to total inorganic arsenic exposure. Therefore, inorganic arsenic dietary exposure has arouse extensive attention in recent years. This paper overviewed the new research progress on inorganic arsenic dietary exposure assessment by international organizations, and summarized the present research status in China. Meantime, this paper pointed out that the arsenic species, the bioavailability form, the toxicity and the analysis method of different arsenic species should be emphasized in future. In conclusion, this paper would provide reference for the further study of inorganic arsenic exposure assessment or other related research.

Abstrac:【OBJECTIVE】It is one of the most widely area and damaging environmental problems about soil heavy metal pollution in current. So, it is wide spread concern, and received general attention. A number of assessment methods of heavy metal pollution in soil have proposed at home and abroad, and which had analyzed and made a conclusion by author. Which would lay a foundation for assessment of heavy metal pollution in soil.【METHOD】The single factor index, nemerow index method, comprehensive evaluation mode of geometric mean, pollution load index, index of geo-accumulation, the potential ecological risk index, sediment enrichment factor, potential ecological eisk index, fuzzy mathematical method, grey clustering method, geostatistics method on GIS, method for health risk assessment, method of environment risk index, and so on typical soil heavy metal pollution assessment methods and models in domestic and foreign were summarized. The advantages, disadvantage and application range of those methods were analyzed.【CONCLUSION】It is indicated by the comparison analysis that a variety of evaluation methods have certain limitations and inadequacies. It was necessary for select on better evaluation methods to carry out full analysis of the sample points, comparison of trial and error with the purpose of evaluation and focus on in pollution assessment of soil heavy metals. Finally, combining a variety of methods according to the actual situation were put forward. At the same time，it should start from the ecological effects of heavy metal pollution, development of biological evaluation method.

In order to improving the antibacterial activity property of inorganic copper-based fungicides, Cu2O nanocrystal was prepared via a facile one-pot synthesis by the reduction of fructose in the paper. The sample was characterized by XRD and SEM. In addition, their antibacterial activity of Cu2O nanocrystal and its mixtures containing ZnO and methenamine were also investigated by inhibition zone method. The result suggested cuprous oxide presented active inhibition to Colletotrichum glecosporioides, Valsa mali, Cucumber wilt and Gaeumannomyces graminis var tritici. The inhibition rate of cuprous oxide was more than 90% once its concentration was 0.5 mg/mL. At the same time, the better antibacterial activity to Colletotrichum capsici and Coniothyrium diplodiella, was reached when the mass of ratio of ZnO or methenamine and Cu2O was up to 1:2 respectively. The synergism was disclosed in our experiments.

This study mainly analyzed the concentration of heavy metals in tea products from urban markets using high pressure airtight digestion system, and inductively Coupled Plasma- Mass Spectrometry (ICP-MS) and atomic fluorescence spectrometry. According to theMaximum Levels of Contaminants in Foods (GB 2762- 2012),Residue Limits for Chromium, Cadmium, Mercury, Arsenic and Fluoride in Tea (NY 659-2003), and Green Food-Heber Tea Agricultural Industry Standard of the People''s Republic of China (NY/T 2140-2012), the characteristics of Pb, Cd, Hg and As concentrations in the tea samples collected from markets were determined. The results showed that Pb, Cd, Hg, As concentrations in tea samples ranged from 0.1 to 1.67, 0.0006 to 0.085, 0.00021 to 0.022 and 0.00 to 0.78 mg/kg，respectively. The levels of Pb, Cd, Hg in all tea samples were lower than those safety limitations in the relevant safety standards. However, arsenic concentration in 1.9% of total tea samples exceeded the safety limitation (0.5 mg/kg) inGreen Food-Heber Tea (NY/T2140—2012). All samples with high concentration of As were black tea in bulk. Pb, Cd, Hg, As contentin tea had a certain relevance, correlation analysis showed that there were significant correlations between Pb and As, Hg, Cd, and between Cd and As, too. When selecting the tea on the market, consumers are advised to choose a stereotyped packaging tea, and stereotyped packaging of jasmine tea from Guangxi had high safety coefficient. The quality of bulk tea and that of black tea in the market vary a lot, so the origin, packaging type and price of tea should be taken into consideration to distinguish the quality.

The addition of silicon (Si) and organic fertilizers to soil conditioners can inhibit the transfer of heavy metal ions from soil to crops. However, it is not clear how Si and organic fertilizers affect soil properties and the micro-ecological environment and thereby reduce cadmium (Cd) accumulation in rice. In this study, the effects of L-type soil conditioners containing Si and organic fertilizers on bacterial and fungal community diversity, soil pH, organic matter, and available Si were analyzed with field experiments at two sites. With the increase of Si and organic fertilizer content in soil conditioner, rice yield respectively increased by 16.8-25.8% and 6.8-13.1%, and rice Cd content decreased significantly by 8.2-21.1% and 10.8-40.6%, respectively, at the two experimental sites. Soil microbiome analysis showed that the increase in abundance of Firmicutes and Actinobacteriota bacteria associated with Cd adsorption and sequestration and Basidiomycota fungal populations associated with degradation of macromolecules favored the inhibition of soil Cd activity (soil exchangeable Cd decreased by 14.4-14.8% and 18.1-20.6%). This was associated with an increase in organic matter and Si content caused by applying soil conditioners. In conclusion, L-type soil conditioners, rich in Si and organic fertilizer, can reduce soil Cd bioavailability by regulating the dominant Cd passivating flora in the soil and ultimately reduce Cd accumulation in rice.

Community garden is an important part of urban public space, which is of great significance to the environmental quality, the linkage of urban patches and the maintenance of ecological security pattern. Affected by urbanization and industrialization, urban soil at home and abroad are facing different degrees of heavy metal pollution. Community gardens exist in urban spaces in the form of green spaces, and the soil pollution may affect the safety of community residents. Therefore, it is necessary to carry out ecological restoration research in community gardens and pay attention to the problem of heavy metals in community gardens, to protect the soil environment from being polluted or to reduce the degree of pollution. However, the study of soil pollution in community gardens is still in its infancy and lacks enough attention. Reviewing the related research on community gardens at home and abroad, and starting from the definition, land use, development status and sources of heavy metal pollution in community gardens, this paper systematically sorted out relevant achievements of domestic and foreign community garden soil heavy metal pollution research, and pointed out that in the future, the construction of community gardens should incorporate ecological restoration technology, and the interdisciplinary method should be used to improve the theoretical research framework from multiple perspectives and fields, so as to create a safe and healthy community garden environment.

Strictly controlled farmland refers to the cultivated land with heavy metals’ contents (cadmium, mercury, arsenic, lead and chromium) exceeding the risk control standard specified by Soil Environmental Quality Agricultural Land Risk Control Standards (GB15618-2018). This article evaluated the safety of planting edible crops in strictly controlled farmland, aiming to provide reference for cultivation structure adjustment in strictly controlled farmland, as well as the safe use of contaminated farmland. Present research indicates that the heavy metals in the seeds easily exceed the standards when oil crops, such as rape, peanut, sesame and sunflower, are cultivated in strictly controlled farmland, while heavy metals’ (such as As and Pb) contents in vegetable oil are lower than the safety limits, and the oil is safe for diet. But for Camellia oleifera seed oil, the excessive rate of heavy metals is relatively high, so it is necessary to further evaluate the heavy metals’ accumulation characteristics of Camellia oleifera varieties, and the safety of Camellia oleifera seed oil. Seed meals could be used as animal feeds and organic fertilizers after the removal of heavy metals, which could maximize the utilization of resources. Nevertheless, there is a risk of excessive heavy metals in maize silage cultivated in strictly controlled farmland, while the risk in maize grains is relatively low, and the low heavy metal accumulation maize varieties could be further screened to achieve the purpose of safe production of grains. The safety of heavy metals in tea should be further studied in strictly controlled farmland. Furthermore, it is necessary to improve the standard system of heavy metal safety limits of edible crops, strengthen the research and development of straw treatment and resource utilization technologies, and establish an ecological compensation mechanism of specific crop straw recycling in strictly controlled farmland.

Heavy metal pollution in soil is a global problem. Bioremediation has received widespread attention for its environment friendliness and cost-effectiveness. However, different bioremediation technologies have their advantages and limitations, so fully understanding the characteristics of remediation technologies can make it more economical and effective to remediate contaminated soil. In this paper, we described and compared the mechanism, advantages, limitations and applicability of popular bioremediation methods, including phytoremediation (phytovolatilization, phytostablizatioin and phytoextraction), genetically modified phytoextraction, chelate assisted phytoextraction, and microbial assisted phytoextraction, and suggested the combination of soil chemistry, plant biology, genetics, microbiology and environmental engineering to form efficient and practical bioremediation technology. According to the characteristics of contaminated soil, combining transgenic plants with corresponding improved properties could be an effective method to achieve large-scale remediation of contaminated soil; meanwhile, the stimulating effect of agronomic measures on the biomass of natural super accumulation plant and heavy metal extraction capacity should be further explored. In conclusion, phytoremediation could be combined with other traditional remediation techniques, and the integration of soil, plant and microorganism by transgenic technology could be the best way to develop future remediation technology.

To gain an in-depth understanding of the residue characteristics and risk assessment of mercury in the pond culture environment of Eriocheir sinensis, a total of 14 samples of water bodies and sediment from 7 Eriocheir sinensis aquaculture ponds were collected in Wuxi of Jiangsu. The residue levels of mercury in different forms were analyzed by liquid chromatography-inductively coupled plasma mass spectrometry (LC-ICP-MS), and the risk of mercury residues was assessed by the single-factor method. The results showed that the mercury content in water bodies ranged from ND (not detected) to 18.20 μg/L, mainly inorganic mercury (Hg²⁺), and other forms included methylmercury (MeHg) and ethylmercury (EtHg). The mercury content in sediment environment ranged from 0.01 to 0.022 μg/g, in which the content of inorganic mercury decreased and the content of methyl mercury increased. Compared with NYT 5361-2016 Environmental Conditions of Pollution-Free Agricultural Products - Freshwater Aquaculture Origin, it was found that the mercury content in the water body exceeded the standard in 5 samples, and the exceeding rate was 71.43%; the mercury content in the sediment environment exceeded the standard in 1 sample, and the exceeding rate was 14.29%. Further research on the ecological risk of water inorganic mercury residues to Eriocheir sinensis showed that the risk quotient ranged from 0 to 0.05, far below 1, indicating that the mercury residues in the water body did not affect the safe growth of Eriocheir sinensis. The detection of heavy metal mercury in aquaculture water is of great significance to the healthy growth of Eriocheir sinensis and food safety.

Mulberry is a health care product raw material, which can be used for both medicine and food, and mulberry industry is a new characteristic health industry developed in recent 10 years. In order to ensure the healthy development of this industry, in this paper, the mulberry production, mulberry disease and pest prevention and control, the formulation of mulberry products’ standard, the use of agricultural inputs and the quality and safety of mulberry products were summarized. In addition, the main factors affecting the quality and safety of mulberry products were analyzed, such as the great damage caused by diseases and pests, the problem of pesticide and heavy metal residues caused by the nonstandard use of pesticides and the pollution of the planting areas, and the imperfect quality and safety standards. Suggestions were put forward including speeding up the screening and registration of special pesticides for mulberry field, improving the quality standard system, and strengthening the supervision of mulberry quality and safety. In the aspect of mulberry products’ safety, the study could provide certain support for the healthy development of the industry and relevant policy formulation.

The paper aims to master the pollution levels of heavy metals in the Yangtze River Basin. The authors selected Anhui and Jiangsu sections in the Yangtze River as sampling points, and collected 16 water samples in June 2016 to determine the contents of 6 heavy metals. The heavy metal contents in the water samples were determined by atomic absorption spectrophotometer. The results showed that: there were no residual Cd in the collected water samples, and the other heavy metals had varying degrees of residues; the residual mean value of Cr, Pb, Cu, Hg and As was 4.276, 1.866, 5.762, 0.016, 1.421 μg/L, respectively; as a whole, higher levels of heavy metals were found in Anqing and Jingjiang, followed by Nanjing and Tongling, while the pollution in Wuhu was the minimal; the Cr pollution in Jingjiang, Anqing and the Hg pollution in Tongling Site 1 reached tertiary level; secondary pollution area was mainly with Cu, Pb level in Tongling Site 1 also reached secondary pollution level, while the otherelements’ pollution was insignificant. This study provides a basis for the effective control of heavy metal pollution in the lower reaches of the Yangtze River, and the realization of scientific management of water environment health risk, and has technical data support for quality and safety assessment of aquatic products.

Desulfurized gypsum is an effective ameliorant of saline-sodic soil, however, the content of heavy metal is a key factor that limits agricultural resource utilization. In order to grasp the agricultural resource utilization feasibility of JISCO group’s desulfurized gypsum, this study comprehensively determined the nutrients and heavy metal concentrations in desulfurized gypsum. The results showed that the macro element contents were very poor, but in contrast, the middle and trace elements were relatively rich and the average contents of calcium, iron, zinc and manganese were 281560, 8063, 15388, 1026 mg/kg, respectively. Heavy metal, chromium, lead and nickel contents were below the second level standard of the national cultivated land soil environment quality. Although cadmium content exceeded the national soil environment quality standard, it was still within the controlled standard of fly ash agricultural resource utilization. These showed that application of desulfurized gypsum to improve saline-sodic soil in proper amount would not have significant effects on the heavy metal contents in soil.