The objective of sustainable agriculture is to maintain high agriculture productivity while preserving a sound environmental quality. However, water quality degradation caused by excessive sediment and nutrient runoff has become a critical environment impact on agricultural watersheds all over the world. Beneficial management practices (BMPs) are therefore designed and implemented to minimize these negative impacts on water environment. In 2004, Agriculture and Agri-Food Canada (AAFC) launched a watershed evaluation of BMPs (WEBs) project with a primary goal of assessing the environmental and economic performance of nine selected small watersheds across Canada under BMPs. The WEBs is composed of four main components, including biophysical evaluation, economic evaluation, hydrologic modeling, and integrated modeling. So far, WEBs has made significant progress in understanding the environmental and economic performance of the BMPs selected for the study and in validating hydrologic models using results from the field-tested BMPs, and WEBs has successfully begun to integrate biophysical and economic findings for planning for broader scales of land. The innovative and interdisciplinary research conducted in the WEBs watersheds will help farmers decide what practices might work best on their farm and will help the governments develop policies and programs to assist farmers in implementing effective BMPs for improving water quality and agri-environment. Additionally, the WEBs project has created the infrastructure, data sets and partnerships needed to continue a long-term watershed research, strengthen the initial findings and clarify the benefits of BMPs under different conditions. A general review of the progress,methods, and major findings of the WEBs project over the past years has been presented, and the necessity for China to implement similar projects has been discussed.

A field experiment, designed to have seven treatments,i.e. U+DCD(urea plus dicyandiamide),U+HQ(urea plus hydroquinone),UF(urea formaldehyde), CMCU(Ca-Mg-P-coated urea),PCU(polymer-coated urea),SCU(sulfur-coated urea)and CK or U(urea), was conducted to explore effects of some typical slow-release fertilizers on methane (CH₄) and nitrous oxide (N₂O) emissions from Helianthus tuberosus fields on tidal flat in Dafeng of Jiangsu Province during its growing season in 2010.Fluxes of CH₄ and N₂O emissions from the field were measured simultaneously with the static chamber-GC method.Results show that in terms of seasonal CH4 emission, the 7 treatments followed the order of U > PCU > UF > SCU > CMCU > U+HQ > U+DCD, emitting 1.25, 0.59, 0.43, 0.27, 0.25, 0.26 and -0.21 kg•hm^-2, respectively. Compared with urea, the slow/controlled-release nitrogen fertilizers reduced seasonal CH₄ emissions by about 53%-80%, but did not vary much among themselves. In terms of seasonal N₂O emission, the treatments followed the order of PCU > SCU > CMCU > U > UF > U+HQ > U+DCD, emitting 2.94, 2.44, 2.27, 2.24, 1.77, 1.47 and 1.34 kg•hm^-2, respectively. Relative to urea, chemically-altered fertilizers reduced seasonal N₂O emission by 21%–40%, whereas physically-altered fertilizers increased total N₂O emission by 1%–31%. The findings suggest that from the aspect of the global warming potential, all the chemically altered nitrogen fertilizers display significant emission reducing effect.

Characteristics of CH₄ and N₂O emissions from wheat fields applied with pig manure in combination with chemical fertilizers were studied using the static chamber method and gas chromatography, and greenhouse effect of the CH₄ and N₂O emitted from the fields were assessed using global warming potentials (P_GW). Results show that the average CH₄ flux from Treatment NPK (the plots applied with chemical fertilizer as in conventional practice), Treatment NPKS (the plots applied with chemical fertilizer plus straw), Treatment 50% PM (the plots applied with half pig manure and half chemical fertilizer) and Treatment 100% PM (the plots applied with pig manure only) was 6.10, 10.26, 5.32 and 2.35 μg•m^-2•h^-1, respectively, the average N₂O flux from Treatments NPK, NPKS, 50% PM and 100% PM was 24.25、38.24、12.21 and 16.06 μg•m^-2•h^-1, respectively. It was found that CH₄ flux increased with temperature after the elongation stage, and N₂O emissions occurred mainly after irrigation or rain during the seeding stage. Compared to Treatment NPK, Treatment NPKS was 57.9% and 52.0% higher in P_GW and P_GW per yield, respectively, while, Treatment 100% PM was 34.3% and 26.0% lower and Treatment 50% PM 48.9% and 48.9% lower in P_GW and PGW per yield, respectively.However,compard with Treatments NPK and NPKS,Treatment 100% PM was significantly lower in wheat yield. It is, therefore, concluded that Treatment 50% PM, that is, to replace half of the rate of chemical fertilizer applied in conventional practice with pig manure, is a good option to reduce CH₄ and N₂O emissions from wheat fields without significant yield reduction.

Spatial variation of soil water content in soil profiles 0-8 m deep as affected by landform and vegetation was studied in the Longtan catchement of Dingxi in Gansu Province.Results show that topographic factors,such as position,inclination and exposure of a slope have signifluences on content of shallow soil water.However,spatial variation of deep soil water is more affected by growth conditions of the vegetation thereupon.The vegetations different in growth condition differ in consumption of soil water,thus the better the vegetation grows,the lower the content of deep soil water is.Slope gradient has significant influences on both shallow and deep soil waters.Soil water content is obviously higher in gentle slopes than in steep in the entire 0-8 m soil profile.Management measures such as soil and water conservation and tillage activities can effectively enhance iniltration of rain water,thus in creasing soil water storage in deep soil layers,and therefore be extrapolated as effective approaches to improvement of soil water regime in this region.

In order to investigate change in nitrogen concetration in precipitation in the agricultural zone of Pudong,Shanghai,its law and affectiong factors,and N deposition flux,rains were sampled monthly over a year(2008)for analysis of nitrate(NO₃^--N)and ammonia nitrogen(NH₄⁺-N)concentrations.Results show that nitrogen concentration in rain water and annual N deposition flux were both quite high in the zone,with the mean concentration of NO₃^--N being 0.44 mg·L^-1 and of N being 1.36 mg·L^-1,and the annual deposition flux of NO₃^--N being 5.19 kg·hm^-2·a^-1 and of NH₄⁺-N,being 15.91 kg·hm^-2·a^-1 ,making the annual deposition flux of TN up to 21.10 kg·hm^-2·a^-1,of which NH₄⁺-N accounted for 75.4%.The concentrations of NO₃^--N and NH₄⁺-N in rain water were lower in the main growig season(April-October)than in the main non-growing season(November-March).However,in terms of deposition flux,NH₄⁺-N was higher in the former than in the latter,while NO₃^--N did not differ much between the two,which was attributed to the comprehensive effect of human activities,number of raing days,rainfall,wind direction,etc..Generally speaking,the nitrogen input with precipitation is of some positive significance to the primary productivity in the study zone,the nitroggen concentrations in rainfall have exceeded the threshold value of water eutrophication,which may intensify eutrophication of the aquatic systems in the zone.

To understand community structure of the litter invertebrates in urban forests in the Central Temperate Zone and effects of large-area artificial coniferous forests on community diversity of the litter invertebrates, investigation of litter invertebrates was carried out in the Jingyuetan National Forest Park, with a total of 8 630 invertebrate individuals collected, belonging to 18 orders in 6 classes under 3 phyla. Results show that Collembola, Acarina, Hymenoptera, Coleoptera, Lepidoptera larvae, Araneae, Diptera larvae, and Lithobiomorpha were the dominant groups, which accounted for 97.91% of the total individuals collected. No significant differences were found between the litter invertebrate communities in natural secondary forests and in artificial coniferous forests in number of groups, density, Shannon-Wiener diversity index, Pielou evenness index , Simpson dominance index, and density-group index, whereas big differences were between the two kinds of forests in  density of larvae of Pseudoscorpionida, Lithobiomorpha, Thysanoptera and Lepidoptera,and in ratio of Acarina to Collembola in number of individuals. Jaccard similarity index of soil invertebrate was 0.67 in both of the two kinds of forests.

In order to lay down a solid basis for the study on ecological function of the macrofungi in the Zijin Mountain ecosystem, species composition and ecological characteristics of the macrofungi were investigated and analyzed. Through a two-year field investigation, a total of 290 species of macrofungi were recorded, belonging to 120 genera of 49 families. The habitats they were found in could be sorted into types of evergreen-deciduous broadleaf mix forest, coniferous-broadleaf mix forest, coniferous forest, bamboo groves, and shrubby wasteland. By trophic type, they could be grouped into lignicolous (151 species), entomophilous (151 species), and ectomycorrhizal (49 species), and entomogenous species (2 species). By floral composition, they could be classified into the following distribution types, i.e. Cosmopolitan (18.97%), North Temperate (35.86%), North Temperate-Australia (13.45%), Temperate-subtropical or Tropical (7.59%), Eurasian (5.86%), Eastern Asia-North America (5.17%), China-Japan (2.07%), and China (10.00%).

Her'er Village in Shizong County of Yunnan Province was chosen as a case of study for analysis of change in agricultural germplasm resources diversity therein and its causes. And a total of 66 kinds of agricultural germspasm resources were collected and collated.Strategies for protection of the resources in those villages have been discussed. Results show that the diversity in the village was quite abundant before 1980, but it was affected by a series of factors, such as modern farming and economic development, losing a great number of indigenous varieties, and most of the preserved indigenous varieties were closely related to the local traditional life style and production, especially culture of the nationality. Take Hei'er glutinous rice as an example, causes of its preservation and the threats it is faced with were analyzed.Meanwhile,some other indigenous varieties or species, like rape, ginger, peanuts and so on, were also found of high value worthy preserving in the village. These findings suggest that community-specific strategies and policies, such as ecological compensation, stimulation of villagers' enthusiasm, utilization of the strength of traditional knowledge and culture, exploitation and development to the full extent of the indigenous agricultural germplasm resourcesm, and village-based farmer household responsible conservation,  should be taken to promote preservation and sustainable utilization of the valuable indigenous varieties.

Effect of light, as affected by orientation and canopy, on deformation of fruits and seeds of Magnolia officinalis was explored through analysis of fruits and seeds collected from different positions or bearings of the canopy of M. officinalis trees for phenotypic index. Results show that the effect of orientation is significant, making the fruits and seeds in the south and east of the canopy better than those in the west in phenotypic shape, and those in the north the poorest. The effect of position in the canopy is also significant. The fruits and seeds growing in the middle layer of the canopy are better than those in the top layer, and much better than those in the bottom layer. No significant synergistic effect of orientation and canopy is found. Compared with fruits, seeds are stabler in phenotypic character.

Groups of earth worms (Eisenia foetida) were raised in laboratory. Group I was fed with the highest naturally acceptable dose of wild shepherd's purse agglutinin (WSA) transgenic cotton (Gossypium hirsutum) leaves, Group II with twice as much, Group III with non-transgenic parent cotton leaves as control, Group IV with cow dung as negative control and Group V with pesticide as positive control. The objective of the study is to explore effects of planting WSA transgenic cotton on survival, growth, and reproduction of E. foetida. Results of the 49 d experiment show that there was no significant difference in death rate, weight, SOD activity, GST activity, cellulase activity, number of earthworm cocoons and number of baby earthworms between Group III and Groups I and II, which suggests that WSA transgenic cotton does not have any significant adverse effects on E. foetida.

To understand effects of tea volatiles on foraging behavior of jumping spiders, Evarcha albaria, the technology of solid phase micro-extraction-gas chromatography-mass spectrometry (SPME- GC-MS) was used to first study effect of leaf-feeding of its preys, false-eye leafhoppers (Empoasca vitis), on release of volatiles from affected tea leaves and at the same time observation was made of foraging behavior of jumping spiders beside different odor sources (or in foraging patches) on a spider behavior observation platform, It was found that intact tea leaves released only a minute amount of volatiles, while Empoasca vitis-bitten tea leaves gave out 14 kinds of volatiles. Once placed near different odor sources, control (intact leaf) or treatment (bitten leaf)  jumping spiders, regardless of male or female, did not show much preference to control or treatment in their first choice or much difference in frequency of their moving into foraging patches affected by different odor sources. However, they stayed significantly longer in the patch of E. vitis-bitten tea leaves. The findings suggested that E. vitis biting of tea leaves induced release of volatiles from the leaves and the change in kind and content of the volatiles, which led to the difference in duration of E. albaria staying in different foraging patches.

A field experiment was carried out to have all the straws of the preceding rice crop returned to the field by burying them into furrows to the depth of 20,30,40 and 50 cm,sparately,at a rate of 2kg·m^-1.The experiment was designed to study effects of this practice on moisture,temperature,bulk density and porosity of the soil in the wheat field.It was found that 12 days after rainfall,soil moisture was significantly lower in the plots with straws buried into furrows 20 and 30 cm in depth than in the plot without straw buried,but not so significant in the plots of with straws buried into furrows 40 and 50 cm in depth.Temperaure of the soil underneath the straw did not vary much in all th straw burial plots,demonstrating that the buried straw has an insulating effect to the soil below.Straw burial could also significantly lower bulk density and increase totao porosity of the soil,expcept in the plot with straw buried only 20 cm in depth,thus making the plaw layer of the soil looser.

Effects of application of urea and （NH₄）₂SO₄ on nitrification in and acidification of red soils different in initial pH(5.14,4.77 and 4.34)were studied through incubation experments.It was found that application of urea accelerated nitrification in and thereby acidification of the three soils,and that at the end of the incubation,soil pH decreased by 2.14,1.23 and 0.56 units,separately,in the three soils relative to their respective maximum pHs observed during the incubation.Apllication of （NH₄）₂SO₄ also accelerated nitrification in the soil hign in initial pH(>5.0),but it had no significant effect on acidification of the soil.However,nitrification in and acidification of the two soils low in initial pH(<5.0)were inhibited by the application of （NH₄）₂SO₄.Soil acidification rates were found to be linearly correlated with nitrification rates in the three soils.These findings suggest that nitrification of NH₄⁺-N in the soil is one of the main factors responsible for the acidification of the red soil of crop fields,but urea and （NH₄）₂SO₄ showed different effects on nitrification in and acidification of these red soils.

Soil samples were collected from a paddy field of red soil, treated with different rates of ammonium sulfate and incubated indoors at 15, 25 and 35℃, separately, for exploration of short-term effects of the treatments on nitrification, microbial biomass and microbial community diversity in the paddy red soil. Results show that NH₄⁺ content was not a significant factor of temperature in treatments the with same in ammonium sulfate application rate, while NO₃^- content was a significant factor of temperature in CK (control) and the Treatment Conventional with ammonium sulfate application rate (pure N 120 mg·kg^-1), but not either in the Treatments Moderate (N 600 mg·kg^-1) and high (1200 mg·kg^-1) in ammonium sulfate application rate. Nitrification rate increased significantly with rising temperature in CK and Treatment Conventional, while it was generally low in Treatments Moderate and High, and did not vary much with temperature. In the treatments incubated under the same temperature, nitrification rate declined with increasing ammonium sulfate application rate. In Treatments Moderate and High, soil microbial biomass carbon was a significant factor of ammonium sulfate application rate, and decreased with increasing of application rate (P<0.05), and in the treatments the with same in ammonium sulfate application rate, it varied with temperature, showing a decreasing order of 25℃ > 15℃ > 35℃. BIOLOG analysis showed that the AWCD, Shannon, Simpson and McIntosh indices were low in Treatments Moderate and High. Under 25℃, CK, among all the treatments, was the highest in AWCD, Shannon, Simpson and McIntosh indices, and Treatment Conventional followed. Overuse of ammonium sulfate may possibly undermine soil biological structure and function.

Seven IAA(indole-3-acetic)-producing strains were isolated from the rhizosphere of peanuts growing in red soil. Among the 7 strains, Strain L4 was the highest in IAA excreting capability (135.67 μg•mL^-1 in 24 h of cultivation), in addition to its phosphate-dissolving capability. Based on its morphological feature, some of its physiological and biochemical characteristics and its 16S rRNA sequence analysis, it was identified as Arthrobacter chlorophenolicus (GenBank Accession No. JQ277449). Single factor tests were designed to explore conditions optimal to growth and fermentation of the strain. Results show that the optimum conditions for its growth differed from those for its IAA excretion. The conditions optimal both to its growth and to its IAA secretion as well were 5-6 in initial pH, volume 50 mL•250 mL^-1 in liquid volume in flask, 30 ℃ in temperature, and 24 h of shaking culture. The best carbon and nitrogen sources for its growth was maltose and yeast extract, but for its IAA production, xylose and KNO₃, respectively.

Root excretion of oxygen is an important feature of Sagittaria trifolia. For better understanding the characteristics of the radial oxygen loss (ROL) from roots of the plant in natural sediment, high-precision dissolved oxygen microelectrodes were used to measure penetration depth and distribution of oxygen under different light intensities (dark and light). Substantial difference in oxygen distribution was observed between parts of the roots. Thickness of the oxygen diffusion layer in the rhizosphere under light and in dark varied along the root in the following order: at 1/2 of the root length (0.98 and 0.72 mm) > at 3/4 (0.68 and 0.28 mm) > at root tip (0.58 and 0.44 mm) > at 1/4 of the root (0.42 and 0.32 mm). Content of dissolved oxygen on root surface under light varied along the root in the following order: at 1/2 of the root length (64.56% of air saturation) > at 3/4  (52.73%) > at root tip (38.55%) > at 1/4 (20.55%), which was related to barrier to ROL, development of aerenchyma, and metabolism and respiration of the tissue. ROL from the roots of S. trifolia, no matter under light or in dark, occurs all the time, and is significantly affected by light intensity. Both the content of dissolved oxygen on root surface and the thickness of the oxygen diffusion layer in the rhizosphere are higher under light than in dark. Among all the measuring points, the point at 1/2 of the root length had the highest ROL in both light conditions (P<0.05). Under light significant differences were found between all the other points in content of dissolved oxygen, but in dark the contents of dissolved oxygen at these points tended to be on the same level (P>0.05).

In order to develop methods for bioremediation of acid soils,hydroxyl release from roots of wheat seedlings in a hydroponic experiment as affected by form of nitrogen fertilizer under acidic conditions was investigated with an automatic titration system.Results show that pH of the nutrient solutions,4.0 in initial pH and 15:1,3:1 and 1:1 in NO₃^-/NH₄⁺  molar ratio separately,increased after 6 days of wheat culturing.The higher the molar ratio,the greater the increase in solution pH.Correspondingly,the absorption of nitrate by wheat and the release of hydroxyl from wheat roots also increased with the rising molar ratio.These findings suggest that the preferential absorption of nitrate by wheat and subsequent release of hydroxyl from wheat roots cause increase in solution pH.In solutions the same in NO₃^-/NH₄⁺ molar ratio,being 3:1,and varied in initial pH,the increases in solution pH and hydroxyl release followed the order of:initial pH 4.0>initial pH 4.5>initial pH 5.0,suggesting that lower pH condition favors nitrate uptake by wheat and hydroxyl release from wheat roots.A 10-hour pH-stat experiment shows that wheat roots released more hydroxyl under pH-stat conditions than under non-pH-stat conditions.The higher the molar ratio,the greater the difference.It is,therefore,feasible to develop a new method for bioremediation of acid soil based on the preference of wheat to absorb nitrate and release hydroxyl from roots under acidic conditions,that is to say,to increase the release of hydroxyl by regulating nitrate content in the soil and hence to increase soil pH.

The Baishuica Reservoir and the Cangcun Reservoir,are two medium-sized reservoirs designated as sources of drinking water for residents in Shaoguan City,Guangdong Province.The reservoirs were sampled once every month throughout the year of 2011 for comprehensive evaluation of their quality using trophic status index(TSI),for classification of the phytoplanktons into functional groups,and for analysis of characteristics of the succession of dominant functional groups in the reservoirs throughout the year and their key environmental affecting factors.Results show that the Baishuica Reservoir is an oligotrophic aquatic system,while the Cangcun Reservoir an oligo-mesotrophic one.Throughout the year,45 genera of phytoplanktons under 7 phyla were collected and could be sorted into sixteen functional groups.In the Baishuica Reservoir,functional groups tolerant to low nutrient environments were in dominancy all the year around and only during the high water season could some eutrophication-tolerant functional groups be detected,while in the Cangcun Reservoir,eutrophication-tolerant functional groups were detectable all the year round and gained apparent dominancy during the high water season,but they were succeeded by the functional groups tolerant to low nutrient environments in dominancy during the low water and normal water seasons when nutrient contents were low.Variation of nutrient content in the water is the fundamental cause leading to succession of phytoplankton functional groups in dominancy,while changes in water environmental factors caused by changes in the rainy season are innegligible factors triggering the succession in the two reservoirs. 

For the purpose of understanding relationships of functional diversities of soil microbial communities in mulberry gardens with the pollutants of polycyclic aromatic hydrocarbons(PAHs),the Biolog method was employed to evaluate response of soil microbial communities in a roadside mulberry garden to PAHs pollution in functional diversity.Results show that PAHs pollution of the soil varied in degree,showing an order of Section 2(located between Sections 1 and 3)>Section 3(farthest from the highway)>Section 1(closest to the highway).Biolog analysis indicates that the three sections followed the order of 2>3>1 in average well color development(AWCD) of carbon utilization of soil microbes.Section 2 was the highest in Shannon index and Gini index and significantly higher than Sections 1 and 3,while in Shannon evenness Section 1 was significantly lower than Sections 2 and 3.Section 2 was the highest in soil microbial activity and abundance of microbial community structure and followed by Sections 3 and 1.Principal component analysis shows that the differences in physiological function of the soil microbial community were sharp between the sections,and embodied mainly in metabolism of carbohydrates and amino acids.Redundancy analysis reveals that soil microbes in Section 2 was the most closely related to PAHs pollution,indicating that higher PAHs concentration is more likely to stimulate physiological activities of the soil microbes in the mulberry garden and also their metabolism function to some extent. 

Through batch experiments,performances of NaOH-modified larch sawdust adsorbing and decoloring Reactive Black 5(KN-B),Reactive Red 24(K-2BP) and Reactive Blue 19(KN-R) were investigated.Results show that in acid conditions,the sawdust could decolor quite well the three dyes in wastewaters.In wastewater,3 in initial pH,adsorption and decoloration rate of the three dyes declined with rising temperature,but rose with application rate of the saw-dust and content of NaCl,and went upwards first and then downwards with rising initial concentration of reactive dyes.Under the conditions of 3 in initial pH and 298 K in temperature,isothermal adsorption of the three dyes on the sawdust fittedthe Langmuir adsorption model quite well.Of the three dyes,KN-B,K-2BP and KN-R,the monolayer sorption capacity Qmax was measured to be 22.32,10.47 and 14.93 mg·g^-1,respectively,and the adsorption thermodynamic parameter ΔG298 K,-12.61,-9.77 and-14.45 kJ·mol^-1,respectively,demonstrating that the adsorption was a spontaneous physical process.Under the conditions of the experiment,the kinetic adsorption data all fitted the pseudo second-order kinetic adsorption equation.In terms of adsorption rate constant,the three dyes followed an decreasing order:KN-R>KN-B>K-2BP.To sum up the findings regarding isothermal adsorption and kinetic adsorption,it can be conclu-ded that the three reactive dyes follow the same order in decoloring effect as in adsorption rate constants. 

A method using solid-phase extraction and gas chromatograph-microelectron capture detector(GC-ECD) was developed to detect flufilprole and its metabolites in plant,soil and water in paddy fields.Water samples were extracted with methylene chloride,soil samples first with acetone and then with ethyl acetate and plant samples first with acetonitrile and then with CarbonNH₂ and at the end cleaned up with solid phase extraction(SPE) for analysis with GC-ECD.Results of the analysis show that the lowest content of pollutants detected was 0.01 mg·L^-1 in the water and 0.015 mg·kg^-1 in the soil and the plant.When 0.05-1.0 mg·L^-1(or mg·kg^-1) of the pollutants were added into the field,the recovery rate of using this method was in the range of 75.1%-109.2% with variation coefficient being 1.0%-7.9%.This method is simple,accurate,and readily applicable in the analysis of paddy field samples. 

Controlling and reducing the total amount of agricultural pollution is one of the top priorities of the energy saving and discharge reduction strategy during the Twelfth Five-Year Plan period of China.However,so far there is no such an index system in the current environment management and technology for agricultural pollution reduction.A rational and practical index system will help us to better understand the situation of agricultural pollution and promote agricultural pollution reduction.The basic principles and methods of developing an index system has been elucidated.Considering comprehensively characteristics of the production and discharge processes of different types of agricultural pollution,an index system for agricultural pollution reduction was preliminarily developed for planting,livestock and poultry breeding and aquaculture,in the hope that it would provide parameters key to the study on accounting systems for reduction of some major agricultural pollutants as well as some basic technical support for working out discharge reduction techniques and methods.Based on the problems that may exist in implementing the current agricultural pollution reduction strategies,relevant suggestions are brought forth to further consummate the index system. 

Acute toxicity of chlorpyrifos(CPF) on crayfish(Procambarus clarkii) was studied with the static test method.In the acute exposure experiment,crayfish was exposed to CPF at the following concentrations,0,2,10,20,40,and 80 μg·L^-1.Results show that the higher the CPF concentration,the higher the toxicity to the crayfish.The 24,48 and 96 h ρ(LC₅₀) was(28.24±2.81),(19.50±2.03) and(13.13±1.70) μg·L^-1,respectively,and the safe concentration was(2.79±0.31) μg·L^-1.The lethal concentration of CPF to 50% of crayfish [ρ(LC₅₀)] decreased significant with time,which fitted a hyperbolic decay model(r=0.999 9,P<0.000 1).Histopathological observation of the crayfish revealed that CPF pollution caused serious damages to its main organs,such as epithelial hyperplasia of the heart,impregnation of cardiac muscle bundles with haemocytes;swollen neorones,chromatolysis,change of cells from multipolar to round shape,necrosis and disorganization of nerve fibres,constriction and congestion of hepatopancreas tubules with more vacuoles;vacuolation surface deposition of melanin and impregnation with haemocytes of gill tissues and atrophy and dissolution of muscle fibers.The study enriched the database of aquatic toxicology and helped accumulate basic data for control of proliferation of CPF pollution and development of ecological farming of crayfish P.clarkii. 

Samples of soils and plants were collected from 3 electroplating plant contaminated areas in Chongqing for analysis in laboratory to investigate concentrations of chromium(Cr),nickel(Ni),zinc(Zn) and copper(Cu) therein and to further explore characteristics of the 23 dominant plants accumulating and translocating heavy metals.Results show that in the soils,the average concentration of Cu,Zn,Cr,and Ni was 560.0,722.6,1 364.3 and 735.7 mg·kg^-1,respectively,and about 1.40,1.45,3.90,and 3.68 times,respectively,the threshold value in Grade Ⅲ of the "Standard for Soil Environmental Quality"(GB 15618-1995).The characteristics of plants absorbing,accumulating and transferring heavy metals varied with species and parts of plant,location of contaminated area and kind of metal.Most of the plants in these areas had heavy metals accumulated in the roots.Only Hemarthria compressa and Mentha haplocalyx displayed their characteristics of being Cr hyperaccumulators,with Cr concentration in shoots reaching 1 559.2 and 1 914.6 mg·kg^-1,respectively,on average,BTC(biological transfer coefficient) 1.29 and 1.58,respectively,and BAC(biological accumulating coefficient) 1.58 and 1.79,respectively.Besides the two,there were 14 other plants whose Cr concentrations in shoots were over 100 times higher than those of ordinary plant species,with Cr concentrations ranging from 121.2 to 694.3 mg·kg^-1 and averaging 376.4 mg·kg^-1,and 8 others whose Ni concentrations in shoots were over 100 times higher than those of ordinary plant species,with Ni concentrations ranging from 220.3 to 532.1 mg·kg-¹ and averaging 344.1 mg·kg^-1.In summary,the findings indicate that these plants are ideal species of plants for phytoremedying soils polluted with multi-heavy metals from electroplating plants.