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.

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.

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.

This paper summarized the existing preparation technologies of nano-selenium, and compared the advantages and disadvantages of different preparation technologies. The research of nano-selenium’s role in improving crop growth, product quality and crop resistance to diseases and pests, and extending shelf life was reviewed. At the same time, the alleviation effects of nano-selenium on crop physiology and biochemistry, plant primary and secondary metabolite synthesis, and agricultural product quality under heavy metal stress were explored. While increasing the selenium content of crops, nano-selenium can continuously improve the quality and efficiency of agricultural industry, which is reflected in regulating the content of trace elements in crops, enhancing plant health, preventing and controlling pests and diseases, reducing the risk of crop yield reduction and fruit quality deterioration, and inhibiting the accumulation of heavy metals. Summarizing previous scientific research achievements is conducive to understanding the benefits of nano-selenium, which is easy to be absorbed by animals and plants, to agriculture and other fields, providing technical ideas for the development of healthy and green agriculture and functional agricultural products, and impelling the modern industrial system construction with scientific and technological strength.

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.

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.

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.

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.

【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.

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.

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.

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.

The entry of heavy metals into soil may cause degradation of soil quality and lead to changes in the ecological characteristics of soil microorganisms. The impacts of heavy metal types and concentrations on microbial respiratory rate, biomass, biomass carbon, diversity, community structure, and functional genes in soil were summarized. Additionally, research in the field of microbial molecular ecology of heavy metal-contaminated soil was prospected, aiming to provide a reference for studying the effect of heavy metal pollution on soil microbial characteristics.

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.

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.

After absorbed by plants, the heavy metals from soil will accumulate in different parts of the plant through lateral and vertical migration. The lateral migration includes the pathways of symplast and apoplast. The vertical migration includes the pathways of xylem and phloem. The factors affecting the migration of cadmium, lead and zinc in plants include barrier structure, transport, physiological metabolites and energy supply. The study of the migration characteristics of heavy metals in plants provides a certain basis for the phytoremediation of soil polluted by heavy metals and the safe utilization of agricultural soil.

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.

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.

Cadmium is one of the most important toxicity elements and it can transfer easily in soil and from soil to plant. Calcium is one of the essential elements for plant growth and it plays an important role in plant growth and signal transduction.[Objective][Method] In order to understand more clearly the ecological effects of cadmium-calcium interactions on plants, explore the interaction mechanism of Cd and Ca coexistence and make the best of the relationship between the Cd and Ca, it is possible to provide scientific foundation for preventing and controlling heavy metals contamination.[Result]This paper reviewed the ecological effects of cadmium-calcium interactions on plants, including: (1) In the process of plant uptake, cadmium and calcium were antagonistic relationship. On the one hand, Cd could inhibit the absorption of Ca by plants to limit the growth of plants; On the other hand, Ca could inhibit the absorption of Cd by plants to relieve cadmium toxicity. (2)The application of exogenous Ca could promote the growth of photosynthetic pigments and the synthesis of photosynthetic pigments under Cd toxicity. (3) In the process of regulating the activities of antioxidant enzymes, the application of exogenous Ca could enhance antioxidant enzyme activities to reduce oxidative damage.[Conclusion]Thus, the effects of cadmium and calcium on plant growth, photosynthetic pigments and antioxidant enzyme activities were antagonistic.

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.

Mining, chemical industry, metallurgy, agricultural cultivation discharge heavy metal pollutants into rivers, lakes and seas, resulting in heavy metal residue pollution of fish. Heavy metal residues in fish have the characteristics of enrichment, biological toxicity, and persistence, and are difficult to degrade through their own actions. It not only threatens the development of fisheries and the health of aquatic ecology, but also the safety of human diet. The article categorizes the accumulation characteristics and summarizes the accumulation patterns of metal residues in fish. Furthermore, the sources, occurrence, and migration and transformation patterns of metal residues in fish are analyzed. Finally, developmental and constructive suggestions for the current monitoring work are put forward, in order to provide reference for further research on heavy metal residues in fish.

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.

To scientifically evaluate the soil environment of cultivated land in western Qinghai-Tibet Plateau and improve the quality of cultivated land according to local conditions, the soil fertility (organic matter, total nitrogen, available phosphorus, available potassium, slow-release potassium etc.) and heavy metal pollution (As, Hg, Cr, Pb, Cd) of cultivated land were analyzed in four counties of western Ngari (Burang, Zanda, Gar, Rutog). Standard comparison method, single factor index method and Nemerow comprehensive index method were used to evaluate the soil environmental quality of the cultivated land. The results showed that the Nemero comprehensive fertility index of the cultivated land in the study area was 1.74, which belonged to grade 3, and soil fertility was average. The soil was deficient in organic matter and total nitrogen, rich in phosphorus and potassium, relatively rich in medium and trace elements except available zinc and available molybdenum. And the Nemero comprehensive pollution index was 0.71, which reached the warning line. The pollution was mainly concentrated in Burang and Gar. As and Cr exceed the heavy metal risk control value by 27.5% and 2.5%, respectively. In addition, Cd was 95% higher than the background value of the Qinghai-Tibet Plateau. In conclusion, the cultivated land of Rutog is fertile and pollution-free, which can be developed as the key cultivated land planting area. But organic matter and nitrogen should be properly supplemented during cultivation to ensure crop growth. Furthermore, it is necessary to pay attention to As pollution in Burang to ensure 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.

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.

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.

Soil environmental quality standards in China have established the limit for total chromium content in soil. To understand the effects of heavy metal chromium on ecological environment and soil organism, it is necessary to analyze different forms and valences of chromium in detail. In this study, the occurrence form, and the migration and transformation of heavy metal chromium in soil were discussed, especially the determination methods of different forms and valences of chromium. Sequential extraction method is still the main method for form analysis of chromium in soil. Compared with the solid-liquid extraction method and the technology of chromium separation, enrichment and determination based on soil liquid samples, direct solid sample analysis does not require sample pretreatment and avoids the form transformation of the element. In the future, more rapid and simple methods for determining heavy metals in soil will be developed.

Abstract: In this paper, the authors reviewed the present research status of the effects of heavy metal on turfgrass,which contained the effects on growth, physiology ,biochemistry and phytoremediation; the capability of absorption and accumulation.On the basis of the present status,pointed out the existing problems and future directions on this field.

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.

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.

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.

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.

【Objective】 The aim of this survey was to study the arsenic (As) contents in various feed ingredients from different provinces in China, providing a scientific basis for controlling As contents in the feed ingredients, and even for guiding feed companies to establish a scientific process on As detection. 【Method】A total of 40 types of 4 054 feed samples were collected from 31 provinces, municipalities and regions, and then the As contents of them were measured by Ion chromatography-inductively coupled plasma mass spectrometer (IC-ICP-MS). 【Result】The results showed that the average As contents of these 40 kinds of feed ingredients ranged from 5.21 to 13 292.0 μg·kg^-1, and the distribution of As contents in different species of feed ingredients was as follows: mineral ingredients (5 018.6 μg·kg^-1)>animal ingredients (1 704.8 μg·kg^-1)>straw ingredients (1 239.0 μg·kg^-1)>pasture ingredients (500.3 μg·kg^-1)>cereal by-products (329.24 μg·kg^-1)>plant protein ingredients (72.99 μg·kg^-1 )>cereals (38.07 μg·kg^-1 ). Meanwhile, the distribution of As contents of cereals, cereal by-products and straw ingredients was as follows: corn straw>corn by-products (corn gluten meal, spray corn cortex and corn DDGS)>corn; wheat straw>wheat by-products (wheat bran, wheat DDGS and wheat middling)>wheat; rice straw>rice by-products ( rice bran and defatted rice bran)>rice>broken rice, which concerned the capacities of different parts of cereals gathering As from soil and water, root>leaf>stem>chaff>grain . The results in comparison with As contents of corn, wheat or soybean meal from different provinces (regions) are extremely significant (P<0.01) respectively, demonstrating As contents among same type of samples from different regions are significant also. Moreover, the ratios of As contents exceeding the limit standard, based on hygienical standard for feeds, have been calculated among the 40 kinds of feed ingredients. As contents in cereals, plant protein ingredients and pasture ingredients were under the limit standard. Nevertheless, As contents of only defatted rice bran in cereal by-products presented the over-limit ratio of 2.8%; As contents of only fish meal in animal ingredients showed the over-limit ratio of 5.3%; The over-limit ratio of rice straw in straw ingredients was 27.4%; Both limestone and dicalcium phosphate in mineral ingredients were with high over-limit ratios 30.8% and 60%, respectively. Over-limit ratios of As contents in different kinds of feed ingredients were as follows: dicalcium phosphate>limestone>rice straw>fish meal>defatted rice bran.【Conclusion】 The above results showed that the As contents in feed ingredients varied greatly in different kinds and regions. The As contents of those cereals relatives ingredients presented a common rule, that is, As contents of straw ingredients were highest, successively, cereals by-products and cereals. Especially, As contents of dicalcium phosphate, limestone, rice straw, fish meal and defatted rice bran were above the limit standard sometimes, which could be considered as high risk feed ingredients. Therefore, the As content in basal diets from different types and regions should be considered in the preparation of diets. It is necessary to improve As detection frequency to make sure of the As contents in animal diets under the safe limits according to the GB 13078-2017 strictly.

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.

【Objective】 Lotus (Nelumbo nucifera) is a traditional edible and medicinal homologous crop in China, yet its abundant genetic resources lack functional characterization. This research aimed to functionally identify genes involving in the accumulation/tolerance of trace mineral nutrients and heavy metal elements in lotus, thereby accumulated gene resources that facilitated increased nutrient efficiency and stress tolerance, so as to provide a theoretical basis for the genetic improvement of lotus. 【Method】The representative Xianglian lotus variety, Cunsanlian was used as the experimental material. Initially, a yeast expression cDNA library of lotus was constructed and transformed into Saccharomyces cerevisiae. It was then screened on plates containing excessive cadmium (Cd), manganese (Mn), zinc (Zn), copper (Cu), iron (Fe), and aluminum (Al) stress to isolate target genes mediating stress tolerance in positive yeast clones. Finally, the functional verification of the selected tolerance genes was conducted through combining bioinformatics analysis and yeast complementation verification. 【Result】A yeast cDNA library of lotus was constructed with a capacity exceeding 10⁶ yeast monoclonal clones, a recombination rate of 100%, and an average insertion fragment size greater than 1 000 bp. Following the screening on stress plates, 13 genes for Cd tolerance, 4 for Mn tolerance, 4 for Zn tolerance, 3 for Cu tolerance, 7 for Fe tolerance, and 1 for Al tolerance were identified. Among these, 3 genes were able to mediate tolerance to both Fe and Mn. These genes were distributed on all lotus chromosomes except chromosome 6.【Conclusion】A high-quality yeast expression cDNA library of lotus was constructed, and screened 29 genes mediating resistance to excess trace mineral nutrients or heavy metal elements, accumulating gene resources for lotus genetic improvement for enhanced nutrient efficiency and the prevention of heavy metal accumulation.

黑水虻幼虫对有机废弃物的取食范围广,可有效缓解日益增长的有机废弃物带来的环境污染问题,获得的昆虫产品富含高蛋白和脂肪,而且所含的氨基酸成分多样,可作为良好的饲料原料用于动物饲料生产。但是,由于有机废弃物中存在大量重金属及致病菌,取食有机废弃物的黑水虻可能存在潜在的生态风险和健康风险。文中综述了重金属和致病菌对黑水虻的影响及其风险评估模型,为有机废弃物安全转化黑水虻昆虫蛋白提供思路。