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1.
Chlorobenzenes (CBs) are a group of organic pollutants that pose a high environmental risk due to their toxicity,persistence and possible transfer in the food chain.Available data in literature show that CBs are detected in different environmental compartments such as soil,water,air and sediment.The widespread presence of CBs in the environment is related to their former extensive use in agriculture and industry.Some CBs are ranked in the list of priority pollutants by the Stockholm Convention,and their reduction or elimination from the environment is therefore of high importance.Environmental risk assessment of CBs requires knowledge on the role and importance of the main environmental fate processes,especially in soil.Furthermore,development of remediation strategies for reduction or elimination of CBs from the environment is related to the enhancement of fate processes that increase their dissipation in various environmental compartments.The main objectives of the current review were to present up-to-date data on fate processes of CBs in the soil environment and to explore possible remediation strategies for soils contaminated with CBs.Dechlorination of highly-chlorinated benzenes is the main degradation pathway under anaerobic conditions,leading to the formation of lower-chlorinated benzenes.Biodegradation of lower-chlorinated benzenes is well documented,especially by strains of adapted or specialized microorganisms.Development of techniques that combine dechlorination of highly-chlorinated benzenes with biodegradation or biomineralization of lower-chlorinated benzenes can result in useful tools for remediation of soils contaminated with CBs.In addition,immobilization of CBs in soil by use of different amendments is a useful method for reducing the environmental risk of CBs.  相似文献   

2.
Currently, plant diseases and insect infestations are mainly controlled by the extraneous application of pesticides. Unfortunately, the indiscriminate use of such agrochemicals can cause ecological and environmental problems, as well as human health hazards. To obviate the potential pollution arising from the application of agrochemicals, biological control of soilborne pathogens or insect pests using antagonistic microorganisms may be employed. Certain soil bacteria, algae, fungi, plants and insects possess the unique ability to produce hydrogen cyanide(HCN), which plays an important role in the biotic interactions of those organisms. In particular, cyanogenic bacteria have been found to inhibit the growth of various pathogenic fungi, weeds, insects, termites and nematodes. Thus, the use of HCN-producing bacteria as biopesticides offers an ecofriendly approach for sustainable agriculture. The enzyme, HCN synthase,involved in the synthesis of HCN, is encoded by the hcnABC gene cluster. The biosynthetic regulation of HCN, antibiotics and fluorescent insecticidal toxins through the conserved global regulatory GacS/GacA system is elaborated in this review, including approaches that may optimize cyanogenesis for enhanced pest control. In addition, the effects of bacterially synthesized HCN on the production of indole acetic acid, antibiotics and fluorescent insecticidal toxins, 1-aminocyclopropane-1-carboxylate deaminase utilization and phosphate solubilization may result in the stimulation of plant growth. A more detailed understanding of HCN biosynthesis and regulation may help to elaborate the precise role of this compound in biotic interactions and sustainable agriculture.  相似文献   

3.
Low availability of phosphorus(P) is a major constraint for optimal crop production, as P is mostly present in its insoluble form in soil. Therefore,phosphate-solubilizing bacteria(PSB) from paddy field soils of the Indo-Gangetic Plain, India were isolated, and their abundance was attempted to be correlated with the physicochemical characteristics of the soils. Ninety-four PSB were isolated on Pikovskaya's agar medium, and quantitative phosphate solubilization was evaluated using NBRIP medium. The isolates solubilized P up to a concentration of 1 006 μg mL~(-1) from tricalcium phosphate with the secretion of organic acids. These isolates were identified by 16 S rRNA gene sequence comparison, and they belonged to Gammaproteobacteria(56 isolates),Firmicutes(28 isolates), Actinobacteria(8 isolates), and Alphaproteobacteria(2 isolates). Phylogenetic analysis confirmed the identification by clustering the isolates in the clade of the respective reference organisms. The correlation analysis between PSB abundance and physicochemical characteristics revealed that the PSB population increased with increasing levels of soil organic carbon, insoluble P, K~+, and Mg~(2+). The promising PSB explored in this study can be further evaluated for their biofertilizer potential in the field and for their use as potent bio-inoculants.  相似文献   

4.
A study was carried out on contribution of iron phosphate to phosphorus nutrition of rice plant under waterlogged and moist conditions,respectively,by use of synthetic Fe^32 PO4.nH2O,tagging directly the iron phophate in calcareous paddy soils.Results showed that under waterlogged condition,similar to iron phosphate in acidic paddy soils.that in clacareous paddy soils was an important source of phosphorus to rice plant ,and the amount of phosphorus originated from it generally constituted 30-65% of the total phosphorus absorbed by rice plant.  相似文献   

5.
中国化肥使用带来的环境问题   总被引：7，自引：0，他引：7  
CAO Zhi-Hong 《土壤圈》1996,6(4):289-303
The current status of chemical fertilizers production and consumption in China as well as their important roles in Chinese modern agriculture are discussed with special concerns to the environmental issues related to chemical fertilizer use.On the one hand.the total amount of chemical fertilizer produced is insufficient to meet the agricultural needs.On the other hand.the production and consumption of chemical fertilizers in China are obviously not balanced.In some areas over application of nitrogen fertilizers and loss of phosphate fertilizer due to soil erosion have resulted in some undesirable environmental problems such as increase of nitrate in water and eutrophication of water bodies.Maximum scientific uses of organic manures in combination with reasonable use of chemical fertilizers are part of good practices not only in increasuing soil productivity and keeping sustainable agriculture development but also in minimizing their detrimental effects on the environment.  相似文献   

6.
Shi  W. M.  Liu  Z. Y. 《土壤圈》1991,1(1):73-81
Large amounts of phytosiderophore are detected from both the solution and the rhizosphere soil when cereal crops are under Fe deficiency stress.The extension of phytosiderophore in the rhizosphere soil is found only within 1 mm apart from the root surface.The rate of phytosiderophore secretion is negatively related to chlorophyll content in young leaves and positively related to the Fe-solubilizing capacity.Results from in vitro experiments whow 10 μmoles mugineic acid can dissolve 501 μg Fe from iron hydroxide and 146 ug from strengite.Thus,phytosiderophore can considerably enhance the soil iron availability by increasing the solubility of amorphous iron hydroxide and iron phosphate,and active Fe is consequently accumulated in the plant rhizosphere,43% higher than in the bulk soils There is evidence to support that mugineic acid chelates with Fe%3 at a rate of 1:1 in the acid condition.In addition,we observe mugineic acid has certain effects on mobilization of P as well as Fe by dissolving the insoluble iron phosphate,And phytosiderophore seems to be an effective remedy for the chlorosis of dicotyledonous plants.  相似文献   

7.
Samples of 21 soil profiles and 165 top soils from an area of approximate 1.5km^2 on red-earthy hill landscape were collected and analysed.The content of Ca,Mg,K,P,Fe,Mn,Zn and Cu in soils relate with the kind of parent material and the position of topography,however,there is great variation due to the local difference of the form of soil utilization.From the difference in spatial distribution of elements content,it is believed that eight kinds of elements are lost by chemical leaching and physical translocation,meanwhile some are added (such as Ca,P,K,Mg) and some mobilized (such as Fe,Mn,Zn,Cu and P) through cultivation,fertilization and irrigation in the soils on the landscape investigated.The sectional differentiation in abundance or deficiency of elements in top soils on the landscape investigated is distinct,which is important for carrying out agricultural management and reasonable fertilization according to local conditions.  相似文献   

8.
As one of the most important and essential macronutrients next to nitrogen,phosphorus(P)is important for plant development,but it is the least mobile nutrient element in plant and soil.Globally,P is mined from geological sediments and added to agricultural soils so as to meet the critical requirements of crop plants for agronomic productivity.Phosphorus exists in soil in both organic and inorganic forms.The various inorganic forms of the element in soil are salts with calcium,iron,and aluminum,whereas the organic forms come from decaying vegetation and microbial residue.There is a huge diversity of plant microbiomes(epiphytic,endophytic,and rhizospheric)and soil microbiomes that have the capability to solubilize the insoluble P and make it available to plant.The main mechanism for the solubilization of inorganic P is by the production of organic acids,which lowers soil pH,or by the production of acid and alkaline phosphatases,which causes the mineralization of organic P.The P-solubilizing and-mobilizing microorganisms belong to all three domains,comprising archaea,bacteria,and eukarya.The strains belonging to the genera Arthrobacter,Bacillus,Burkholderia,Natrinema,Pseudomonas,Rhizobium,and Serratia have been reported as efficient and potential P solubilizers.The use of P solubilizers,alone or in combination with other plant growth-promoting microbes as an eco-friendly microbial consortium,could increase the P uptake of crops,increasing their yields for agricultural and environmental sustainability.  相似文献   

9.
Trace element-contaminated soils (TECSs) are one of the consequences of the past industrial development worldwide.Excessive exposure to trace elements (TEs) represents a permanent threat to ecosystems and humans worldwide owing to the capacity of metal(loid)s to cross the cell membranes of living organisms and of human epithelia,and their interference with cell metabolism.Quantification of TE bioavailability in soils is complicated due to the polyphasic and reactive nature of soil constituents.To unravel critical factors controlling soil TE bioavailability and to quantify the ecological toxicity of TECSs,TEs are pivotal for evaluating excessive exposure or deficiencies and controlling the ecological risks.While current knowledge on TE bioavailability and related cumulative consequences is growing,the lack of an integrated use of this concept still hinders its utilization for a more holistic view of ecosystem vulnerability and risks for human health.Bioavailability is not generally included in models for decision making in the appraisal of TECS remediation options.In this review we describe the methods for determining the TE bioavailability and technological developments,gaps in current knowledge,and research needed to better understand how TE bioavailability can be controlled by sustainable TECS management altering key chemical properties,which would allow policy decisions for environmental protection and risk management.  相似文献   

10.
It is globally accepted that soil carbon (C) dynamics are at the core of interlinked environmental problems,deteriorating soil quality and changing climate.Its management remains a complex enigma for the scientific community due to its intricate relationship with soil nitrogen (N) availability and moisture-temperature interactions.This article reviews the management aspects of soil C dynamics in light of recent advances,particularly in relation to the availability of inorganic N pools and associated microbial processes under changing climate.Globally,drastic alterations in soil C dynamics under changing land use and management practices have been primarily attributed to the variation in soil N availability,resulting in a higher decomposition rate and a considerable decline in soil organic C (SOC) levels due to increased soil CO2 emissions,degraded soil quality,and increased atmospheric CO2 concentrations,leading to climate warming.Predicted climate warming is proposed to enhance SOC decomposition,which may further increase soil N availability,leading to higher soil CO2 efflux.However,a literature survey revealed that soil may also act as a potential C sink,if we could manage soil inorganic N pools and link microbial processes properly.Studies also indicated that the relative,rather than the absolute,availability of inorganic N pools might be of key importance under changing climate,as these N pools are variably affected by moisture-temperature interactions,and they have variable impacts on SOC turnover.Therefore,multi-factorial studies are required to understand how the relative availability of inorganic N pools and associated microbial processes may determine SOC dynamics for improved soil C management.  相似文献   

11.
Sewage sludge is a valuable source of organic matter, N, P and certain micronutrients that have beneficial effects on plant growth and biomass production. However, sanitary regulations often require the stabilization of sewage materials prior to applying them to soils as biosolids. Environmental regulations also demand appropriate management of biosolid‐N to avoid groundwater contamination. Because stabilization processes usually make sewage sludge less putrescible, we hypothesized that the mineralization rates of organic‐N from stabilized biosolids would be affected. Therefore, this study aimed to evaluate the mineralization of five biosolids in two soils – a sandy Spodosol and a clayey Oxisol. Digested sludge, composted sludge, limed sludge, heat‐dried sludge and solar‐irradiated sludge were mixed with soil samples at a concentration of 32.6 mg N/kg soil (1.0 dry t/ha of digested sludge) and incubated at 25 °C in a humidity chamber for 23 weeks. Results showed that the stabilization processes generally slowed the release of mineral‐N in soils relative to the digested sludge from which the biosolids originated. However, increments in the levels of mineral‐N were more influenced by soil type than by the type of stabilization process applied to the sewage sludge. Mineralization rates were up to 5‐fold higher in the Oxisol than in the Spodosol soil, and as a result, organic‐N in biosolids mineralized 10–24% in Spodosol and 23–52% in Oxisol. Any appropriate plan for the management of biosolid‐N for plant use should consider the interaction between soil type and biosolid type.  相似文献   

12.
Polybrominated diphenyl ethers (PBDEs) have been found at high levels, up to 7.6?×?106?pg/g, in biosolids commonly applied to agricultural soils. A field investigation was carried out in this study to measure concentrations of PBDEs in biosolid-amended agricultural soils in which various amounts of biosolids (20 and 80?t/ha) had been applied. Concentrations of PBDEs in surface soils that had received a single application of 80?t/ha biosolids were one to two orders of magnitude greater than that in soil, which had received a single application of 20?t/ha of biosolids. Assessment of PBDEs levels at different depths, between 0.05 and 1.05?m, in soils that received 80?t/ha biosolids, showed that PBDEs were mobilized from the surface soil to lower depths. Total PBDEs concentrations decreased from 10,250?pg/g dry weight basis (dw) in the 0.05?m soil layer to 220?pg/g dw at a depth of 1?m. The distribution of PBDEs with depth and cation exchange capacity of the soil could be described as exponential functions. The coefficients of correlation ranged from 0.47 to 0.57 and 0.47 to 0.67, respectively. Despite the deviation in the experimental measurements induced by variables, such as non-uniform biosolid application, heterogeneity of the soil, and the uneven surface of the field, variations of PBDEs along the soil profile in the biosolid-amended soil were clearly demonstrated.  相似文献   

13.
This greenhouse study evaluated the use of drinking-water-treatment residuals (WTRs) to reduce the bioavailability of metals in the biosolid-amended agricultural alkaline soils. Results showed that increasing the application rate of biosolids increased the accumulation of lead (Pb), nickel (Ni), copper (Cu), and cadmium (Cd) in corn (Zea mays cv. single hybride 10), with greater metal concentrations in roots than in shoots. However, the addition of WTRs (1–4%, w/w) to the soil amended with 3% biosolids significantly (P < 0.05) decreased the concentrations of soil diethylenetriaminepentaacetic acid (DTPA)–extractable metals. The accumulation of Pb, Ni, Cu, and Cd in corn significantly correlated with the DTPA-extractable metal concentrations in the soils. Plant metal concentrations were significantly affected by the soil type, application rates of biosolids and WTRs, and the ratio of WTRs to biosolids in the soils. The 1:1 application ratio of WTRs to biosolids at the 3% application rate effectively reduced the accumulation of metals in corn tissues.  相似文献   

14.
ABSTRACT

Although biosolids are a rich source of plant nutrients, there is concern about the potential heavy metal uptake by crops grown on biosolid-amended soils. This study was conducted to determine the effects of limed or composted biosolids and flue gas desulfurization gypsum (FGDG) on edamame growth, nodule development, and metal uptake. Two consecutive crops of edamame were grown on 40 and 80 T ha?1 biosolid-amended soil with and without 10 T ha?1 FGDG. Biosolids with or without FGDG did not reduce biomass, nodules, or grain yields in the first harvest and increased yields of all three tissues in the second harvest. Lead and cadmium concentrations in grain and biomass were below the instrument detection limits. Copper, manganese, and zinc were within the ranges normally found in soybean grain. In this pot study, biosolids and FGDG did not reduce edamame growth or increase grain metal concentrations to levels of concern.  相似文献   

15.
固体废弃物及土壤中磷的形态分析技术   总被引：2，自引：0，他引：2  
王涛  周健民  王火焰 《土壤学报》2011,48(1):185-191
畜禽粪便等固体废弃物及土壤中磷的形态分析对于管理固体废弃物、提高磷素利用率、减少磷素流失风险具有重要意义。自20世纪初以来,已提出多种固体废弃物及土壤中磷素形态分析的方法,包括化学分级、酶水解法、X射线衍射(XRD)、红外光谱(FT-IR)3、1P核磁共振(31P NMR)、X射线吸收近边结构(XANES)等。本文系统总结了一些固体废弃物及土壤中磷素形态分析的方法,比较了其特点,指出只靠单一的方法并不能很好地鉴定固体废弃物及土壤中磷素的形态,必须综合考虑运用多种方法,从而为磷素形态分析提供方法选择的依据,同时为进一步发展固体废弃物及土壤中磷素形态分析新技术奠定基础。  相似文献   

16.
畜禽粪便等固体废弃物及土壤中磷的形态分析对于管理固体废弃物、提高磷素利用率、减少磷素流失风险具有重要意义。自20世纪初以来,已提出多种固体废弃物及土壤中磷素形态分析的方法,包括化学分级、酶水解法、红外光谱(FT-IR)、X射线衍射(XRD)、31P核磁共振(31P NMR)、X射线吸收近边结构(XANES)等。本文系统总结了一些固体废弃物及土壤中磷素形态分析的方法,比较了其特点,指出只靠单一的方法并不能很好的鉴定固体废弃物及土壤中磷素的形态,必须综合考虑运用多种方法,从而为磷素形态分析提供方法选择的依据,同时为进一步发展固体废弃物及土壤中磷素形态分析新技术奠定基础。  相似文献   

17.
A pot scale trial investigated the agronomic performance of two organomineral fertilizers (OMF15—15:4:4 and OMF10—10:4:4) in comparison with urea and biosolids granules to establish ryegrass (Lolium perenne L.). Two soils of contrasting characteristics and nitrogen (N) application rates in the range of 0–300 kg ha?1 were used over a period of 3 years. Fertilizer effects were determined on: (1) dry matter yield (DMY) and crop responses, (2) nitrogen use efficiency (NUE), and (3) selected soil chemical properties. Ryegrass responded linearly (R2 ≥ 0.75; P < 0.001) to organomineral fertilizers (OMF) application increasing DMY by 2–27% compared with biosolids but to a lesser extent than urea (range: 17–55%). NUE was related to concentration of readily available N in the fertilizer: urea and OMF showed significantly (P < 0.05) greater N recoveries than biosolids. Total N in soil and soil organic matter showed increments (P < 0.05), which depended on the organic-N content in the fertilizer applied. Soil extractable P levels remained close to constant after 3 years of continuous OMF application but increased with biosolids and decreased with urea, respectively (P < 0.05). The application of biosolids changed soil P Index from 5 to 6; hence, there is a need to monitor soil P status. Both OMF10 and OMF15 formulations are suitable for application in ryegrass.  相似文献   

18.
Environmental sustainability of animal agriculture is strongly dependent upon development of approaches to minimize the potential environmental impacts of applying animal manures. The excess manure and its nutrients (primarily phosphorus) in intensive animal production regions may need to be exported to other areas to comply with increased regulations on manure management. In our previous study we generated a variety of granulated products from poultry litter to achieve export of excess litter from the southwestern Ozarks, AR, USA. Our objective in the present study was to determine the effect of the application of poultry litter and granulated litter products on phosphorus (P), arsenic (As), copper (Cu) and zinc (Zn) dynamics in two Arkansas soils (Dewitt silt loam and Hector sandy loam). Poultry litter and granulated products were mixed with the surface horizon (0–15 cm) of soils at two application rates: P‐based (100 kg total P per hectare) and N‐based (160 kg plant‐available N per hectare). Soil–litter mixtures were incubated at 25 °C for 21 days. Sub‐samples were removed at 1, 7 and 21 days to determine the solubility and availability of P, As, Cu and Zn in soils. Results suggest that when litter was applied at 100 kg total P per hectare, contents of P, As, Cu and Zn were significantly greater in the soils amended with litter and granulated products than in the control (soil alone). However, the contents of P, As, Cu and Zn did not significantly differ in the soils amended with either normal litter or granulated litter products at total P or plant‐available N‐based application rates. This suggests that poultry litter granulation is a sound management practice that can be used to reduce concerns with fresh litter transport and potentially improve P and trace element balances in intensive poultry production regions, especially when applied on a plant‐available N basis.  相似文献   

19.
The impact of biosolids on soil processes in five soils under pasture was assessed. Five biosolid treatments (control, dried pellets, compost, biosolids at 200 kg N/ha, and biosolids at 800 kg N/ha) were mixed in 0- to 10-cm-deep soil in lysimeters each year. Nematodes were sampled after 2 years. Many of the nematode populations and indices showed significant soil effects. Nematode responses to the range of biosolid amendments were similar across the five soils. Few populations showed an interaction between the type of amendment and the soil. The most marked response to amendment was that of bacterial-feeding Rhabditidae, in which populations were affected by the weight of the biosolid amendment. Nematode contribution to the soil processes in these soils was not adversely affected by the application of biosolids.  相似文献   

20.
Geochemical sorption and biological demand control phosphorus (P) retention and availability in soils. Sorption and the biota predominantly utilize the same inorganic form of P, from the same soil pool, on the same time scale, and thus are likely to compete for P as it flows through the available pool. In tropical soils, P availability is typically quite low and soil geochemical reactivity can be quite high. We tested whether greater P sorption strength in tropical soils resulted in lower biological uptake of available P. Since the strength of soil sorption and biological demand for P change as ecosystems develop and soils age, we used soils from the two upper horizons from three sites along a 4.1 million-year-old tropical forest chronosequence in the Hawaiian archipelago. We evaluated the strength of geochemical sorption, microbial demand, and the partitioning of added available P into biological versus geochemical soil pools over 48 h using a 32PO4 tracer. Soil sorption strength was high and correlated with soil mineral content. The amount of added phosphate geochemically sorbed versus immobilized by microbes varied more between the organic and mineral soil horizons than among soil ages. Microbial activity was a good predictor of how much available P was partitioned into biological versus geochemical pools across all soils, while sorption capacity was not. This suggests that microbial demand was the predominant control over partitioning of available P despite changes in soil sorption strength.  相似文献   

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