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841.
842.
除草剂灭草烟在土壤中的吸附、脱附 总被引:13,自引:0,他引:13
对咪唑啉酮类除草剂灭草烟在8种土壤的吸附、脱附进行了研究,对振摇时间、温度、土壤pH值的影响作了探讨,并对吸附、脱附常数与土壤的理化性质的相关性进行了分析。结果表明,灭草烟在土壤中吸附常数和土壤〔H+〕(OM%)呈正相关,灭草烟在土壤中脱附的难易程度与土壤有机质含量呈负相关 相似文献
843.
保护地番茄养分利用及土壤氮素淋失 总被引:45,自引:0,他引:45
在施用不同复合肥料的条件下,对保护地蔬菜蕃茄对N、P、K养分的吸收利用及保护地条件下土壤的硝酸盐淋洗进行了研究,结果表明,复合肥的品种及施肥水平对番茄的产量影响不大,与CK相比番茄果实增产12..7%-18.4%;复合肥N、P养分的当季利用率不足10%,而K素的当季利用率也不超出25%,传统的大水漫灌条件,蔬菜保护地土壤硝酸盐的淋洗状态相当严重,并有可能造成地下水的硝酸盐污染,长期过量施肥及大小漫灌等措施是造成土壤养分累积、硝酸盐淋洗严重、肥料利用率低的根本原因,图2表3参11 相似文献
844.
Su J Wang H Kimberley MO Beecroft K Magesan GN Hu C 《Environmental science and pollution research international》2007,14(7):529-535
Goal, Scope and Background Biosolids, i.e., treated sewage sludge, are commonly used as a fertilizer and amendment to improve soil productivity. Application
of biosolids to meet the nitrogen (N) requirements of crops can lead to accumulation of phosphorus (P) in soils, which may
result in P loss to water bodies. Since 1996, biosolids have been applied to a Pinus radiata D. Don plantation near Nelson City, New Zealand, in an N-deficient sandy soil. To investigate sustainability of the biosolids
application programme, a long-term research trial was established in 1997, and biosolids were applied every three years, at
three application rates, including control (no biosolids), standard and high treatments, based on total N loading. The objective
of this study was to evaluate the effect of repeated application of biosolids on P mobility in the sandy soil.
Materials and Methods Soil samples were collected in August 2004 from the trial site at depths of 0–10, 10–25, 25–50, 50–75, and 75–100 cm. The
soil samples were analysed for total P (TP), plant-available P (Olsen P and Mehlich 3 P), and various P fractions (water-soluble,
bioavailable, Fe and Al-bound, Ca-bound, and residual) using a sequential P fractionation procedure.
Results and Discussion Soil TP and Olsen P in the high biosolids treatment (equivalent to 600 kg N ha−1 applied every three years) had increased significantly (P<0.05) in both 0–10 cm and 10–25 cm layers. Mehlich 3 P in soil of the high treatment had increased significantly only at
0–10 cm. Olsen P appeared to be more sensitive than Mehlich 3 P as an indicator of P movement in a soil profile. Phosphorus
fractionation revealed that inorganic P (Al/Fe-bound P and Ca-bound P) and residual P were the main P pools in soil, whereas
water-soluble P accounted for approximately 70% of TP in biosolids. Little organic P was found in either the soil or biosolids.
Concentrations of water-soluble P, bioavailable inorganic P (NaHCO3 Pi) and potentially bioavailable inorganic P (NaOH Pi) in both 0–10 and 10–25 cm depths were significantly higher in the
high biosolids treatment than in the control. Mass balance calculation indicated that most P applied with biosolids was retained
by the top soil (0–25 cm). The standard biosolids treatment (equivalent to 300 kg N ha−1 applied every three years) had no significant effect on concentrations of TP, Mehlich 3 P and Olsen P, and P fractions in
soil.
Conclusions The results indicate that the soil had the capacity to retain most biosolids-derived P, and there was a minimal risk of P
losses via leaching in the medium term in the sandy forest soil because of the repeated biosolids application, particularly
at the standard rate.
Recommendations and Perspectives Application to low-fertility forest land can be used as an environmentally friendly option for biosolids management. When
biosolids are applied at a rate to meet the N requirement of the tree crop, it can take a very long time before the forest
soil is saturated with P. However, when a biosolids product contains high concentrations of P and is applied at a high rate,
the forest ecosystem may not have the capacity to retain all P applied with biosolids in the long term.
ESS-Submission Editor: Dr. Jean-Paul Schwitzguébel jean-paul.schwitzguebel@epfl.ch 相似文献
845.
Liang XQ Chen YX Li H Tian GM Ni WZ He MM Zhang ZJ 《Environmental pollution (Barking, Essex : 1987)》2007,150(3):313-320
A simple but comprehensive model is developed to quantify N losses from urea applied to a near-trench paddy field, considering all the N-transformations such as urea hydrolysis, volatilization, nitrification, denitrification, and all the important transportations like runoff, lateral seepage, vertical leaching and crop uptake. Seasonal average data of field observations for three crop seasons were used for model calibration and validation, which showed that ammonia volatilization accounted for 26.5-29.4% of the applied N and N uptake by crop occupied 38.2-44.8%, while N losses via surface runoff, vertical leaching and lateral seepage varied from 5.6-7.7%, 4.0-4.9% to 5.0-5.3% of the applied N, respectively. These observed results were well predicted by our model, indicating that the model performed effectively at quantifying N losses via individual processes in a wide range of urea application rates and benefit for developing water and fertilizer management strategies for near-trench paddy fields. 相似文献
846.
Regular ingestion of soils could pose a potential health threat due to long-term toxic element exposure. In order to estimate
the human bioavailability quotients for As and heavy metals, 12 urban roadside soil samples were collected and analyzed for
As, Pb, Cu, Zn, Ni, Co, and Cr using Simple Bioavailability Extraction Test (SBET). The quantities of As, Pb, Cu, Zn, Ni,
Co, and Cr leached from soils within the simulated human stomach for 1 h indicated, on average, 27.3, 71.7, 40.4, 59.3, 17.7,
27.2 and 5.6% bioavailability, respectively. Significant positive correlations were observed between the amounts leached using
SBET and the total amounts dissolved with HNO3-HCl-HF acid mixtures. Stepwise multiple regression analysis indicated that the amounts leached with SBET for As, Pb, Zn,
Ni, and Co were not related to any of the physic-chemical parameters measured (i.e., soil texture, pH, total organic matter).
These results may be valuable for providing input data for risk assessment at sites subject to anthropogenic soil contamination. 相似文献
847.
Acid rain is a problem of increasing agricultural, environmental, and ecological concerns worldwide. This study investigated impacts of simulated acid rain (SAR) on cation leaching from the Latosol in south China. Latosol is an acidic red soil and occurs in the tropical rainforest biome. Laboratory experiments were performed by leaching the soil columns with the SAR at a pH range from 2.5 to 7.0 over a 21-day period. A linear increase in effluent K+ concentration was found at the SAR pH 3.0, whereas an exponential decrease in effluent Na+ concentration was observed at all levels of the SAR pH. In general, leaching of Ca2+ and Mg2+ from the Latosol increased as the SAR pH decreased. There was a very good nonlinear correlation between the removal of soil K+ and the SAR pH (R2 = 0.91), a good nonlinear correlation between the removal of soil Mg+2 and the SAR pH (R2 = 0.83), a fairly good nonlinear correlation between the removal of soil Ca+2 and the SAR pH (R2 = 0.56), and no correlation between the removal of soil Na+ and the SAR pH (R2 = 0.06). Our study further revealed that the removal of soil cations such as K+, Ca+2, and Mg+2 can be quantified by the quadratic polynomial equations. In addition, impacts of the SAR on cation leaching depended not only on the SAR pH but also on the original soil pH. 相似文献
848.
849.
氰氟草酯(Calofop-buty1)是一种芳氧苯氧羧酸酯类除草剂,其迁移、转化和分解等行为对环境及人类健康具有潜在危害.为了解其微生物代谢机制,从长期使用氰氟草酯的稻田土壤中分离到1株氰氟草酯降解菌株,命名为QDZ-B.菌株QDZ-B的16S rDNA基因序列长度为1 400 bp,在RDP数据库比对结果表明其与寡养食单胞菌属菌株的同源性最近,与模式菌株嗜麦寡养食单胞菌Stenotrophomonas maltophilia(AB008509)的同源性为99.8%.根据表型特征、生理生化特性和16S rDNA序列同源性分析,将菌株QDZ-B鉴定为寡养单胞菌属(Stenotrophomonas sp.).接种量为5%时,菌株QDZ-B在基础盐液体培养基中5 d对100 mg L-1氰氟草酯的降解率约为88.2%.菌株QDZ-B的降解效果与接种量成正相关,但接种量大于5%时,降解效率趋于平稳.菌株QDZ-B降解氰氟草酯的最适温度为30℃,最适pH为7.0.通过质谱分析鉴定了3个菌株QDZ-B降解氰氟草酯的代谢产物,分别为氰氟草酸、氰氟草酰胺和2-氟-3-对-乙氧基苯氧基苯酰胺. 相似文献
850.