Degradation kinetics of manure-derived sulfadimethoxine in amended soil

Spreading of contaminated manure into agricultural lands as fertilizer is one of the major routes through which veterinary antibiotics enter the environment. In this study, the degradation of manure-derived sulfadimethoxine, a widely used veterinary sulfonamide antibiotic, in manure-amended soil was investigated. A kinetic model, called the availability-adjusted first-order model based on the first-order kinetics and an assumption of the availability of target compound during the degradation process, was developed and was found to fit sulfadimethoxine degradation well. The effect of initial sulfadimethoxine concentration showed that the degradation rate constant increased with decreasing initial concentration, indicating that the bioactivity of the degrading microorganisms in manure-amended soil was sensitive to sulfadimethoxine concentration. Sulfadimethoxine degradation was accelerated with increasing manure content in amended soil. Degradation in nonamended soil was significantly slower than in manure-amended soil. This indicated that sulfadimethoxine may become more persistent once it reaches soil after leaching from manure and that storage of manure for a certain period before application is needed to diminish sulfadimethoxine contamination. Sulfadimethoxine degradation was effectively enhanced with increasing moisture of amended soil. No adverse effect was observed with manure storage on the degradation of manure-derived sulfadimethoxine in amended soil.     

兽药抗生素的残留状况与环境行为

随着畜牧养殖业的迅速发展,抗生素作为人工投入的生产要素得到广泛应用,在带来增产效应的同时,也造成了抗生素的残留,不仅直接影响动物产品的安全与卫生,而且极大的威胁着环境质量安全、人类的身体健康以及生存环境。本文介绍了兽药抗生素的应用及残留状况,概述了兽药抗生素在环境中的迁移、降解及其对动物、植物、微生物的影响等环境行为,并结合国内外研究现状提出了近期兽药抗生素残留研究的重点内容。     

适宜水分和养分提高土壤中磺酸二甲嘧啶降解率

医疗和养殖过程中抗生素的广泛使用导致了土壤环境中抗生素的污染。为了解进入农田土壤中抗生素的降解规律,该文以养殖业广泛使用的磺胺二甲嘧啶和2种不同养分水平的土壤为试验材料,采用盆栽方法研究了肥料种类(有机肥、NPK肥、N肥、PK肥等)、耕作强度(翻耕、免耕)、水分条件(长期干燥、长期湿润、干湿交替、长期潮湿)及种植作物(种植蔬菜、不种蔬菜)对土壤中磺胺二甲嘧啶降解的影响。结果表明,与不施肥处理比较,施用有机肥、NPK肥、N肥可促进土壤中磺胺二甲嘧啶在土壤中的降解,并以施用有机肥的效果最为明显;但施用PK肥对土壤中磺胺二甲嘧啶的降解影响不明显。翻耕可促进土壤中磺胺二甲嘧啶的降解,干湿交替、长期湿润比长期干燥和长期潮湿土壤环境下更有利于磺胺二甲嘧啶的降解。种植蔬菜比不种蔬菜土壤的磺胺二甲嘧啶的降解率高,根际土壤中磺胺二甲嘧啶的降解高于总体土壤。高养分土壤中磺胺二甲嘧啶的降解一般高于低养分土壤。分析认为,施肥、土壤养分水平、种植蔬菜对土壤中磺胺二甲嘧啶的降解的影响可能主要与这些因素改变了土壤微生物活性有关;翻耕可促进土壤中抗生素的光降解强度。研究认为,施肥、耕作和水分管理可以在一定程度上加速土壤中磺胺二甲嘧啶的降解。     

泰乐菌素和土霉素在农业土壤中的消解和运移

长期施用禽畜排泄物可导致抗生素在土壤中的积累, 对环境产生不良影响.为了解进入农田后抗生素的去向及残留动态, 选择2个典型农业土壤, 利用田间小区试验, 研究了田间实际状况下泰乐菌素和土霉素2种抗生素在土壤中的消解与运移行为.研究表明, 抗生素在土壤中的消解和运移与抗生素种类和土壤性质有关.抗生素在砂质土壤(清水砂)中的下移明显高于粘壤土(泥质田), 泰乐菌素在土壤中的垂直迁移强于土霉素.表层土壤中抗生素因降解和下移随时间逐渐下降, 消解速率在试验初期大于后期, 并且土霉素消解速率大于泰乐菌素.砂质土壤中抗生素的消解速率在试验初期明显高于粘壤土, 但至试验后期, 二者渐趋相似.田间条件下测得的抗生素消解速率明显低于实验室条件下, 这可能与抗生素进入田间深层土壤后稳定性增加有关.农田施用抗生素初期产生的径流中含较高浓度的抗生素, 但随时间(10 d之内)很快下降至检测下限以下; 试验初期径流中抗生素浓度为泰乐菌素大于土霉素, 砂质土高于粘壤土.     

粪肥施用土壤抗生素抗性基因来源、转移及影响因素

随着新型抗生素开发速度的不断下降以及抗性基因(Antibiotic resistant genes,ARGs)的快速出现和传播,细菌抗药性和ARGs对公共健康存在威胁,被公认为当前全球亟待解决的难题。虽然土壤本底存在ARGs,但畜禽粪便施用等人类活动加速了ARGs在土壤环境中的扩散和传播。粪肥施入土壤后,其对土壤微生物的抗性选择压力及基因水平转移导致的ARGs扩散转移将持续存在。畜禽粪便中的抗性细菌所携带的ARGs、土壤中抗生素累积导致微生物产生的ARGs和粪肥刺激含有ARGs微生物的繁殖等均为土壤中ARGs的主要来源。土壤中ARGs可以向水体和农作物传移,并随着食物链向动物及人类传播。自然因素(温度、降水、时间和土壤类型)和人为因素(抗生素的含量和种类、粪便种类和处理方式、重金属含量及生物质炭添加)均会影响土壤中ARGs的持久和扩散。目前,粪肥施用土壤中ARGs污染对环境质量及健康的潜在影响并不完全清楚,建议加强模型建立、溯源、生物地理分布、从污染源向环境介质的转移规律、削减措施和机制等方面研究,以有效遏制ARGs在环境中的污染,真正做到畜禽粪便资源化、无害化利用。     

泛种养结合视角下北京市养殖业土地承载力评估

种养结合是中国未来农业绿色发展的重要方向。其中,对畜禽粪污的土地承载力的准确估算是关键。针对北京市畜禽粪污消纳的土地没有充分利用及其氮磷需求取值不够准确的问题,该研究根据畜禽养殖数据计算了2018年北京畜禽养殖粪污产生量和氮磷养分资源量,以粮地、菜地、园地、部分林地、草地及未利用土地6种地类作为畜禽粪污的消纳场所,利用统计年鉴和ArcGIS估算了6种类型的土地资源量,根据文献综合分析了各地类单位面积的氮磷养分需求量,进而计算了北京市域内畜禽养殖业的土地承载力。结果表明：2018年北京市畜禽养殖总量为453万头猪当量,畜禽粪污产生总量为380.1万t,氮磷养分资源量分别为2.61万及0.53万t。在有机肥全部替代化肥的情况下,仅以耕地（粮地、菜地）作为畜禽粪污的消纳场所,则全市种植业土地能够承载的最大养殖量为675万头猪当量;若以6种土地类型作为畜禽粪污的消纳场所,则为1 089万头猪当量,是仅以耕地作为消纳场所的1.61倍。若有机肥50%替代化肥,仅以耕地为畜禽粪污消纳场所,土地承载力为337.6万头猪当量,则2018年的养殖规模已经超过耕地承载力。若以6种土地作为消纳场所,其土地承载力为544.5万头猪当量,与现养殖规模相比还有20.1%的养殖潜力。因此,在环境保护的前提下促进养殖业的发展,一是要扩大有机肥对化肥的替代比例,二是要将更多的可作为畜禽粪污消纳的土地类型加以充分利用。     

应用Manure-DNDC模型模拟畜禽养殖氮素污染

畜禽养殖是重要的农业面源氮素污染源头,大量的畜禽粪便施入农田后,会加大农田氮素径流和淋溶损失强度。畜禽养殖废弃物氮素污染过程复杂,涉及到动物自身营养循环以及废弃物通过不同途径进入环境的过程,目前大多通过排放系数法估算畜禽养殖过程产生的氮素污染负荷。该文选用最新版Manure-DNDC模型,以山东小清河流域为例,模拟畜禽养殖及废弃物处理的生物地球化学过程,分析氮素在动物、畜禽粪便、农田之间的迁移转化,探讨该过程中氮素的主要损失途径以及污染物负荷的时空变化特征。模拟结果表明,小清河流域2008年畜禽养殖及粪便处理场所氮素径流损失4.66万t,粪便施入农田后的氮素径流和淋溶损失分别为0.1、0.51万t。     

Alterations in total microbial activity and nitrification rates in soil due to amoxicillin‐spiked pig manure

Most veterinary drugs enter the environment via manure application. However, ecotoxic effects of antibiotics are varying as a function of their physicochemical characteristics and for most antibiotics it is still unclear how these substances interact with soil biota. It was the aim of the present study to investigate effects of manure containing different concentrations of the antibiotic amoxicillin (AMX) on microbial‐community function in two different soils over an incubation time of 18 d. Therefore, soil respiration, potential nitrification, and the products of N turnover were measured. We could show that CaCl₂‐extractable amounts of AMX in soil are low, even shortly after the application of high doses together with manure. Thus, not surprisingly basal respiration in soil was not influenced by the addition of the antibiotic with manure. In contrast, mainly shortly after manure addition the kinetic of substrate‐induced respiration was clearly shifted by the treatments depending on the presence of AMX in the manure. Potential nitrification rates in the two different soils were not significantly affected when data were related to the overall incubation time by the application of AMX to the manure. However, shortly after the addition of the manure containing AMX, a tendency to lower turnover rates was visible compared to the application of pure manure.     

应用危险确认模型评估土地管理的可持续发展

New Zealand is highly dependent on its soil resource for continued agricultural production.To avoid depleting this resource,there is a need to identify soils and associated land management practices where there is a risk of soil degradation.Environmental integraity and ecosystem services also need to be maintoained.Accordingly,to ensure sustainable production,The on -and off-site environmental impacts of aldn management need to be identified and managed.We developed a structural vulnerability index for New Zealand soils.This index ranks solis according to their inherent susceptibility to physical degradation when used for agricultural (pasture,forestry and cropping) Purposes.We also developed a rule-based model to assess soil sompaction vulnerability by characterising the combined effects of resistance and resilience,Other soil attributes have been approatised using seven chemical,physical and biological indicators of soil quality.These indicators have been applied in a nation -wide project involving data collection from over 500 sites for a range of land uses.These soil quality data can be interpreted via the World Wide Web -through the in teractive decisionsupport tool SINDI,The land-use impact model is a framework to assess agricultural land management and environmental sustainability,and may be applied to land units at any scale.Using land resource data and information the model explicitly identifies hazards to land productivity and environmental integrity,It utilises qualitative expert and local knowledge and quantitative model-based evaluations to assess the potential environmental impacts of land-management pratices.The model is linked to a geographic information system(GIS),allowing model outputs.such at the environmental impacts of site-specific best management practices,to be identified in a spatially explicit manner,The model has been tested in New Zealand in an area of pastoral land use.Advantages of this risk identification model include:utilising current knowledege of the causes and effects of land-management practices on soil degradation;linking land management practice to both on-and off-site environmental consequences;identifying important gaps in local knowledge,and providing spatially explicit information on the environmental impact of land-management practices.     

京郊畜禽粪肥资源现状及其替代化肥潜力分析

随着都市型规模化养殖业快速发展,畜禽粪尿废物大量排放因缺乏足够面积土地消纳所带来的环境压力很大,而粪尿中的氮磷钾养分与化肥一样对作物同等重要,如何合理利用这些废物资源决定了都市化农业的可持续发展。该文针对京郊养殖业和农用地面积现状,结合调研、收集畜禽养分排泄系数和农田养分需求等参数,估算京郊固液粪便养分资源现状及其替代化肥的潜力。结果表明:京郊畜禽固液粪便中N、P、K养分量分别为58.7×103、21.3×103、29.8×103 t,其中固体粪便N、P、K养分分别为43.1×103、20.3×103和19.7×103 t,京郊畜禽固液粪便可分别满足农田N、P、K养分需求量的99.3%、185.2%、62.7%。大部分区县粪肥中P养分产生量超过作物P需求量,粮田秸秆还田可带入的N、P、K养分分别为11.0×103、1.6×103和15.0×103 t,情景分析表明在秸秆还田条件下,按照磷素平衡原则估算本地区所能消纳的粪肥所带入N、P和K养分数量分别为18.3×103、9.9×103和10.3×103 t,同时需要补充N、K化肥分别为29.8×103和22.2×103 t,其余粪肥则需经过堆肥化处理并输往外地。经过堆肥处理,固体粪肥可提供的N、P、K养分分别下降了23%、11%和12%,外输固体粪肥堆肥可进一步减少农田氮磷负荷以及可能的环境风险。     

Changes in the soil phosphorus status of agricultural land in the Netherlands during the 20th century

The Netherlands has a high cumulative mean phosphorus (P) balance. In the 20th century, cumulative mean P surpluses were ca. 4500 kg P₂O₅/ha. The annual surpluses have levelled off because of manure application limits from 1984 onwards. We report the effect of soil type, land use, and manure policy on changes in soil P of fields in the Netherlands during the 20th century. We used data (>5 million soil P tests) from the soil analysis laboratory BLGG AgroXpertus. Our results show that soil P has increased on average to fairly high and high ratings. Differences between regions and between land use have remained high from the first records in the 1930s; on arable land the increase continued until the end of our study period while on grassland no changes are evident in the last decades. In general regions with high livestock density have high soil P status. Soil P increased in the order bulbfields < grassland < arable land < maize land < horticulture, and in the order loess < clay < peat < sand soils. Spatial variations in P values reflect more the market value of the crops and regional availability of animal manure than (fertilizer) recommendations. Manure policy since 1984 has resulted in increasingly tight restrictions on P application from manure and fertilizers, but the effects are not yet clearly reflected in changed trends in soil P.     

Agricultural land needs protection

Abstract

Since 1960, the amount of arable land per capita in the world has decreased from 0.41 to 0.21 ha. During recent decades, there has also been a significant increase in the impact of soil degradation. It is estimated that 5–10 million ha of agricultural land are abandoned every year as a result of soil degradation and the construction of buildings and infrastructure. The Nordic and Baltic countries have on average more arable land per capita and larger water resources than many other areas of the world. Land and water resources are expected to become gradually more critical, and Northern European arable land is likely to increase in importance in contributing to our basic food and bioenergy demands. It is important that these land resources are protected for future generations. Therefore, soil degradation and exploitation of arable land needs more attention from individuals, society and governments.     

Farmer Perceptions and Responses to Soil Degradation in Swaziland

Soil degradation is globally concerning due to its adverse effects on the environment and agricultural production. Much of Swaziland is at risk from degradation. This paper assesses farmer perceptions and responses to soil degradation in 2002 and 2014, focusing on two land uses that underpin rural livelihoods: arable land and rangeland areas. It uses repeat household surveys and semi‐structured interviews, in two case study chiefdoms in the country's middleveld (KaBhudla and Engcayini) in the first longitudinal study of its kind. We find that observations of land degradation are perceived mainly through changes in land productivity, with chemical degradation occurring predominantly on arable land and physical degradation and erosion mainly in rangeland areas. Changes in rainfall are particularly important in determining responses. While perceptions of the causes and impacts of degradation largely concur with the scientific literature, responses were constrained by poor land availability, shorter and more unpredictable cropping seasons because of changing rains and low awareness, access to or knowledge of agricultural inputs. We suggest that sustainable arable land management can be enhanced through improved access to alternative sources of water, use of management practices that retain soil and moisture and greater access to agricultural inputs and capacity building to ensure their appropriate use. We suggest collaborative management for settlement planning that integrates soil conservation and livestock management strategies such as controlled stocking levels and rotational grazing could improve land quality in rangeland areas. Together, these approaches can help land users to better manage change. © 2016 The Authors. Land Degradation & Development published by John Wiley & Sons Ltd.     

Uptake of veterinary medicines from soils into plants

Medicines play an important role in the treatment and prevention of disease. Whereas the side effects on human and animal health resulting directly from treatment have been widely documented, only recently have the occurrence and fate of medicines in the environment and the potential consequences for human health been recognized as an issue warranting consideration. Medicines have been shown to be released to soils and to persist in the environment. This study was performed to investigate the potential for a range of veterinary medicines to be taken up from soil by plants used for human consumption and to assess the potential significance of this exposure route in terms of human health. Soil analyses indicated that, for selected substances, measurable residues of these are likely to occur in soils for at least 5 months following application of manure containing these compounds. Experimental studies on the uptake of veterinary medicines into carrot roots (tubers) and lettuce leaves showed that only florfenicol, levamisole, and trimethoprim were taken up by lettuces, whereas diazinon, enrofloxacin, florfenicol, and trimethoprim were detected in carrot roots. Measured concentrations in plant material were used to model potential adult human exposure to these compounds. Although exposure concentrations were appreciable in a few instances, accounting for approximately 10% of the acceptable daily intake values (ADI), all were lower than the ADI values, indicating that, at least for compounds with properties similar to those considered here, there is little evidence of an appreciable risk. This exposure route may, however, be important when veterinary medicines have a very low ADI, at which they elicit subtle effects over prolonged periods, or when exposure is occurring via a number of routes at once. Although degradation products (produced in the soil or the plant) were not measured, it is possible for some substances that these could increase the risks to consumers.     

四环素在土壤中的吸附与解吸以及镉在其中的影响

采用批平衡实验方法,研究了四环素（TC）在褐土和红壤中的吸附和解吸,以及Cd2＋对四环素在两种土壤上吸附和解吸的影响。结果表明,四环素在褐土和红壤中的吸附可以用Freundlich等温吸附方程拟合,所得lgKf分别为3.039和3.169,这表明四环素在红壤中的吸附能力较强。此外,四环素在两种土壤上的解吸过程都存在滞后现象,所得lgKf,des分别为3.292和3.877,这将可能威胁到土壤环境和人体健康。常见重金属Cd2＋的存在会促进四环素在两种土壤上的吸附,在红壤中表现显著（P〈0.05）;同时红壤中四环素的lgKf,des有所增加,而在褐土中的变化不大。     

Effect of sulfonamide antibiotics on microbial diversity and activity in a Californian Mollic Haploxeralf

Purpose  

Up to 90% of antibiotics that are fed to livestock are excreted unaltered or as metabolites and thus are present in manure. By application of manure as fertilizer, veterinary antibiotics can reach soil and groundwater. The aim of this study is to determine the effect of three commonly used (and simultaneously applied) sulfonamide antibiotics on both function and structural diversity of soil microorganisms. To this end, the activity of the enzymes urease and dehydrogenase was determined, and the composition of phospholipid fatty acids (PLFA) was analyzed.     

Parameter selection and testing the soil nitrogen dynamics model SOILN

Abstract. The SOILN model with a crop growth submodel for grass and cereal crops and the associated soil water and heat model SOIL were selected out of a number of similar models to simulate nitrogen cycling in a soil/crop system. The main parameter values required by the model were selected on the basis of a combination of field experiments and literature sources. Experimental data measured on grassland at Dumfries in the West of Scotland and on arable land at Bush Estate near Edinburgh were used to test the model. Simulated biomass yields and nitrogen contents of harvested biomass were in reasonable agreement with measured values for both grass and cereal crops. There were similar trends in accumulated leached nitrate between the simulations and experiments at the sites. Any discrepancy between simulated and measured nitrate leached appeared to correspond to similar discrepancies between simulated and measured water flow. The comparison between simulated and experimental results suggests that the model with the selected parameter values can simulate nitrogen and carbon cycling both in grassland and in arable land, and make convincing predictions about the effects of varying soil, crop, fertilizer and manure management practices. A basic sensitivity analysis carried out on the parameters determining the biological and biochemical processes showed the model predictions of annual N-leaching are relatively insensitive to all but two of the plant parameters. However, the model predictions of annual N-harvested and dry mass production are sensitive to numerous plant parameters.     

Laboratory study of oxytetracycline degradation kinetics in animal manure and soil

Oxytetracycline (OTC) is a major member of tetracyclines, which are widely administered to animals in confined feeding operations. To diminish the contamination of OTC in the environment, which results from the application of OTC-containing manure as fertilizer in agricultural lands, OTC degradation kinetics in manure and soil under laboratory aerobic conditions was investigated. OTC degradation kinetics was found to be described well by the previously developed availability-adjusted first-order model at all moistures and low temperatures (or=35 degrees C) in manure. At 25 degrees C, OTC half-life was determined to be 8.1 days in manure with moisture at 80%, 33 days in manure-amended soil (amendment ratio at 5%), and 56 days in non-amended soil with both moistures at 20%, demonstrating that OTC may become persistent in the environment once it is released from manure into soil. No pronounced effect of coexistent antibiotics on OTC degradation in manure was observed.     

Impacts of historical land use changes on erosion and agricultural soil properties in the Kali Basin at Lake Balaton, Hungary

Historical land use changes may have significant impact on erosion and agricultural soil properties, including soil degradation by acidification, nutrient leaching and organic matter depletion. The Kali Basin study area, a small catchment of high landscape value located in a national park at Lake Balaton, Hungary, with its historical agricultural records, together with the available unique historical land use data for the last 200 years, provides an opportunity to study and model impacts of historical land use changes on erosion and agricultural soil properties. Comparison of long-term land uses with present soil degradation indicator parameters showed that permanent arable land use has led to degradation of both the physical and chemical properties of soils in the Kali Basin. Application of the SEDEM/WATEM distributed erosion and sediment transport model showed that, despite the low overall sediment export from the catchment, land use changes introduced by property ownership and agricultural changes have decreased average soil erosion in the catchment but increased relative sediment export to Lake Balaton. This is due to changes in the land cover pattern that allow more sediment transported to the river system. The overall conclusion of this study is that besides the size and area proportion of land use types, land use pattern seems to be equally important in soil erosion and degradation processes, thus land use pattern is a key factor for landscape planning and development in the Kali Basin. A relationship between the sociological and agro-ecological reasons for the recorded land use changes is also shown in this study.     

Veterinary antibiotics at environmentally relevant concentrations inhibit soil iron reduction and nitrification

Veterinary antibiotics used in food animal production, subsequently entering the agroecosystem through land application of animal manure, constitute a growing concern. Previous studies have reported inhibitory effects of antibiotics on soil microbial activities, however, treatment concentrations in these studies were often many times greater than the ranges typically found in the environment. When spiked into manure and mixed with soil at environmentally relevant concentrations in a laboratory study, sulfadimethoxine and monensin blocked soil iron reduction over periods extending from a few days to the entire 50-Day experiment. Sulfadimethoxine also had an inhibitory effect on soil nitrification periodically over the course of the study. Respiration and community-level physiological profile parameters were not inhibited by sulfadimethoxine, monensin, or chlortetracycline. We conclude that antibiotics at environmentally relevant concentrations can disrupt soil microbial processes, although the detection of such impact may be antibiotic and/or process specific.