Spatiotemporal characteristics of cultivated land use eco-efficiency and its influencing factors in China from 2000 to 2020

Improving cultivated land use eco-efficiency(CLUE)can effectively promote agricultural sustainability,particularly in developing countries where CLUE is generally low.This study used provincial-level data from China to evaluate the spatiotemporal evolution of CLUE from 2000 to 2020 and identified the influencing factors of CLUE by using a panel Tobit model.In addition,given the undesirable outputs of agricultural production,we incorporated carbon emissions and nonpoint source pollution into the global benchmark-undesirable output-super efficiency-slacks-based measure(GB-US-SBM)model,which combines global benchmark technology,undesirable output,super efficiency,and slacks-based measure.The results indicated that there was an upward trend in CLUE in China from 2000 to 2020,with an increase rate of 2.62%.The temporal evolution of CLUE in China could be classified into three distinct stages:a period of fluctuating decrease(2000-2007),a phase of gradual increase(2008-2014),and a period of rapid growth(2015-2020).The major grain-producing areas(MPAs)had a lower CLUE than their counterparts,namely,non-major grain-production areas(non-MPAs).The spatial agglomeration effect followed a northeast-southwest strip distribution;and the movement path of barycentre revealed a"P"shape,with Luoyang City,Henan Province,as the centre.In terms of influencing factors of CLUE,investment in science and technology played the most vital role in improving CLUE,while irrigation index had the most negative effect.It should be noted that these two influencing factors had different impacts on MPAs and non-MPAs.Therefore,relevant departments should formulate policies to enhance the level of science and technology,improve irrigation condition,and promote sustainable utilization of cultivated land.

Combining CLUE-S and SWAT Models to Forecast Land Use Change and Non-point Source Pollution Impact at a Watershed Scale in Liaoning Province, China

Non-point source(NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent(CLUE-S) and Soil and Water Assessment Tool(SWAT) models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen(TN) and total phosphorus(TP) were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. However, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effectively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.

Research on the Influence of Land Use Changing on Non-point Source Pollution in Heihe River Basin

Based on the exploring of SWAT model suitability in Hei River Basin, this paper analyze quantitatively and compare non-point source pollution loads occurred under different land use scene. At last, the following conclusion can be attained： （1） Land use change exerts tremendous influence on non-point source pollution. Since forest land can save water and reduce soil loss, which decreases greatly the source of non-point source pollution; （2） Strengthening land management and promoting reasonable land use, especially the over 15 degree slope farmland, will be the effective measure to control non-point source pollution and protect the quality of water in the Hei River basin; （3） The best land use situation in Hei River basin should be like the following modes： complying with national water source protection policy, gradual evacuation of river basin population, returning all the sloping farmland which is above 15 degree to forest land, allowing the existence of few farming land below 15 slope degree on the premise that the drinking water quality standard is reached, no unused land, good vegetation covering situation. At then, total nitrogen load is 13.25 kg, total phosphate load is 3.29 kg, which means it will not contaminate

Fractal Analysis on the Spatial Structure of Land Use Patterns in a Non-Point Source Polluted Area in Southern China

Based on the TM remote sensing interpretation of land use data of a non-point source polluted area in southern China in 2015, supported by ArcGIS and the fractal theory, this paper established the perimeter-area fractal equation of the spatial structure of land use types, quantitatively calculated the fractal dimension and stability index of various land use types in this non-point source polluted area in 2015, and analyzed the spatial structure characteristics of land use types. The results showed that the fractal dimension values of the different land use types in the research area ranged 1.141–1.657, and the whole fractal dimension of the research area was 1.206. To be specific, the fractal dimension values of unused land, grass land and rural residential land were high, and the fractal dimension values of dry land, paddy filed and waters were low, and the fractal dimension values of urban land, industrial traffic construction land and forest land were moderate. The area of the land use types whose stability index values were 0.2–0.4 accounted for 89.5% of total area, suggesting that the stability of the spatial structure of land use types of Beibei District in 2015 was not high generally. The rural residential land and urban land of the research area should be planned and managed more properly from now on.

Spatial and Temporal Distribution Characteristics of Agricultural Non-point Source Pollution in Xixi Watershed of Jinjiang Basin

The SWAT model was applied to analyze the temporal-spatial distribution patterns of non-point source pollution loads and the difference of pollution loads of different land use types in Xixi Watershed of Jinjiang Basin. The results showed that both yearly nitrogen and phosphorus pollution loads were evenly distributed during 1973 to 1979,the annual TN pollution from non-point source was 1530 t,or 6. 3 kg / ha,and the annual TP pollution from non-point source was 270 t,or 1. 1 kg / ha during 1973 to 1979 in the watershed. Considerable differences were identified on both monthly nitrogen and phosphorus pollution loads. The TN and TP pollution loads during the flood season( from April to September) accounted for 76. 2% and 75. 8% of the annual load respectively. There were great differences in both TN and TP pollution loads of different land use types in the study area,and the pollution load of both farmland and orchard was higher than that of the other land use types. TN and TP pollution loads of farmland accounted for 66% and 83% of total watershed. There was a great spatial difference in the nonpoint source pollution load of the study area. The critical source areas of non-point source pollution are mainly located at Guanqiao Town,Longmen Town,Changkeng Town,Shangqing Town and Dapu Town,where the efforts of controlling pollution should be made.

GIS and L-THIA Based Analysis on Variations of Non-point Pollution in Nansi Lake Basin,China

Non-point source （NPS） pollution is the main threat to regional water quality, and the estimation of NPS pollution load has become an important task for NPS pollution control in China. Combined with geographical information system （GIS）, the long. term hydrologic impact assessment （L-THIA） model was used to evaluate the temporal.spatial changes of chemical oxygen demand （COD）, total nitrogen （TN） and total phosphorus （TP） in Nansi Lake basin from 2000 to 2010. The results show： 1 ） the estimated COD, TN and TP loads in 2010 are 260017.5, 111607. 7 and 6372.0 t with the relative errors of 2.1%, 2. 0 % and - 8.8 % respectively, and more than 90% concentrated in the raining period from June to September; 2） cultivated land and construction land take up more than 80% of the whole Nansi Lake basin, and the proportions of the three kinds of NPS pollution loads coming from cultivated land and construction land are more than 98%; 3 ） during 2000- 2010, the COD, TN and TP loads increase by 8801. 6, 180.3 and 71.9 t respectively, and become the main impact factors on the water quality of Nansi Lake.

Seasonal variation of nitrogen-concentration in the surface water and its relationship with land use in a catchment of northern China

Surface waters can be contaminated by human activities in two ways: (1) by point sources, such as sewage treatment discharge and storm-water runoff; and (2) by non-point sources, such as runoff from urban and agricultural areas. With point-source pollution effectively controlled, non-point source pollution has become the most important environmental concern in the world. The formation of non-point source pollution is related to both the sources such as soil nutrient, the amount of fertilizer and pesticide applied, the amount of refuse, and the spatial complex combination of land uses within a heterogeneous landscape. Land-use change, dominated by human activities, has a significant impact on water resources and quality. In this study, fifteen surface water monitoring points in the Yuqiao Reservoir Basin, Zunhua, Hebei Province, northern China, were chosen to study the seasonal variation of nitrogen concentration in the surface water. Water samples were collected in low-flow period(June), high-flow period(July) and mean-flow period(October) from 1999 to 2000. The results indicated that the seasonal variation of nitrogen concentration in the surface water among the fifteen monitoring points in the rainfall-rich year is more complex than that in the rainfall-deficit year. It was found that the land use, the characteristics of the surface river system, rainfall, and human activities play an important role in the seasonal variation of N-concentration in surface water.

土壤重金属污染钝化修复研究进展

如何有效治理和修复重金属污染土壤,保障粮食安全成为农业和环境生态领域的研究热点。在优质耕地资源短缺与粮食生产需求的突出矛盾背景下,原位钝化技术被认为是解决土壤重金属污染修复治理的切实可行,且能保证作物安全生产的修复措施。文章从钝化剂种类、钝化修复技术应用中存在的问题等方面综述了重金属污染土壤钝化修复研究的现状,分析了影响土壤重金属钝化修复效果的因素,并对未来重金属污染土壤的钝化修复研究思路提出了建议,以期为科学、合理、高效使用钝化剂和钝化修复技术提供理论指导,实现受污染耕地的安全利用。

长江中下游粮食主产区耕地面源污染时空分异特征

为揭示长江中下游粮食主产区耕地面源污染时空规律,利用长江中下游粮食主产区58个市(州、区)统计数据,采用空间分析模型、重心模型、冷热点分析等方法分析了2009—2019年长江中下游粮食主产区耕地面源污染时空分异特征。结果表明:长江中下游流域整体以及赣湘鄂皖4省2009—2019年耕地面源污染总量和强度总体均呈现出“先升后降”的变化趋势,其中湖北省的耕地面源污染强度与总量均位于前列。2009—2019年耕地面源污染强度总体表现为“西高东低”的空间分布特征,其中江西省整体上一直保持为低污染强度,湖北省则为高污染强度聚集区。长江中下游粮食主产区耕地面源污染强度重心变化呈现出“区间震荡”的规律,且长江中下游粮食主产区耕地面源污染强度重心迁移呈现明显的阶段特征。2009—2019年长江中下游粮食主产区耕地面源污染强度呈现出明显的空间聚集态势,总体表现为“东冷西热”的空间分布格局。因此,长江流域中游段特别是湖北省和湖南省是未来进一步推进耕地面源污染防治的重点区域,要统筹好国家粮食安全和耕地生态安全双重目标。

青海省典型农业区土壤重金属风险评价及来源

探究青海省耕地土壤重金属的累积状况、污染风险与来源,可为青海省耕地土壤重金属治理与防控提供科学依据。以河湟谷地和柴达木盆地耕地土壤为研究对象,采集了84个耕地表层(0~20 cm)土壤样品,测定了Cu、Pb、Cr、Zn和Cd含量,利用单因子污染指数法、地累积指数法、内梅罗综合指数法和潜在生态风险指数法对研究区土壤重金属的污染程度及生态风险进行了评价,并采用相关性分析和主成分分析方法对耕地土壤重金属的来源进行了识别。结果表明:①相较于青海省土壤环境背景值,河湟谷地与柴达木盆地耕地土壤仅有Cd平均含量高于背景值,但所有土壤样品均未超过农用地土壤污染风险筛选值;在两个区域,Cd含量的变异性均最高,分别达到40.87%和40.07%,其他4种重金属的变异系数均低于30.00%;Cu、Pb和Zn含量在两个区域无显著差异,Cr含量在河湟谷地显著高于柴达木盆地,但Cd含量显著低于柴达木盆地。②两个区域耕地土壤污染程度整体上处于清洁水平,综合潜在生态风险为低生态风险水平,但Cd潜在生态风险较高,在两个区域均达到中等生态风险水平。③河湟谷地Cu、Zn和Cd主要受农业活动的影响,Pb和Cr主要受土壤母质的影响;柴达木盆地Cu和Zn主要受母质矿物风化和土壤侵蚀的影响,Pb、Cr和Cd主要受农业生产和管理的影响。综上所述,尽管5种重金属在青海农业区土壤中暂未对农作物质量和人体健康构成威胁,但人类活动对土壤重金属累积的影响不容忽视,特别要关注农用肥料的施用对Cd累积的影响,以预防耕地土壤污染。

江苏省沿江地区耕地面源污染时空特征及脱钩效应

基于市域尺度揭示了2006—2020年江苏省沿江地区耕地面源污染的时空演变特征,并借助Tapio脱钩模型进一步探究了耕地面源污染与农业经济增长的脱钩关系,以期为江苏省沿江地区耕地面源污染防治工作和长江流域农业绿色发展提供参考依据。结果表明,江苏省沿江地区耕地面源污染状况明显好转,且农药面源污染相较于化肥面源污染空间差异更明显;种植业单位面积产值总体呈上升趋势,且具有明显的空间差异性;农业生产与耕地面源污染的脱钩关系呈现出阶段性特征,且强脱钩聚集区出现位移。今后要持续推进化肥农药减量增效工作,加强耕地质量监测评价并建立土壤养护机制,整区域推进高标准农田建设,以实现农业生产与耕地面源污染的强脱钩。

Monitoring of non-point source pollutants load from a mixed forest land use

The aim of this study was to determine the unit load of NPS （non-point source） pollutants including organic variables such as BOD （biochemical oxygen demand）, COD （chemical oxygen demand） and DOC （dissolved organic carbon）, nitrogen and phosphorus constituents, and suspended solids （SS） and their event mean concentration （EMC） of runoff flows from a water-shed of mixed forest land use by intensive field experiments. Field monitoring for continuous measurements of rainfall, flow, and water quality was conducted over 12 storm events during 2008-2009 using automated and manual sampling methods. The EMCs of individual runoff event were estimated for each water quality constituent based on the flow rate and concentration data of runoff discharge. The average EMCs of BOD, COD, DOC, SS, TN （total nitrogen）, NH4^＋-N, NO3^--N, TP （total phosphorus）, PO4^3-P from the mixed forest land were 1.794, 3.498, 1.462, 10.269, 0.862, 0.044, 0.634, 0.034, and 0.005 mg/L, respectively. The annual unit loads of BOD, COD, DOC, SS, TN, NH4^＋-N, NO3^--N, TP and PO4^3--P were estimated as 66.9, 133.2, 55.5, 429.8, 36.5, 1.6, 26.9, 1.3 and 0.1 kg/（ha·yr）, respectively. In addition, affecting parameters on the EMCs were investigated by statistic analysis of the field data. As a result, significant correlations with precipitation, rainfall intensity, and total runoff flows were found in most constituents.

浙江某地区耕地土壤重金属污染特征及生态风险评价

为评估耕地土壤表层重金属污染特征、生态风险水平以及来源,取浙江省某一耕地区域作为研究对象,测定0~50 cm表层土壤的Cu、Ni、Cd、Pb、Hg、As 6种元素含量,采用单因子污染指数和内梅罗指数法分析重金属污染特征,利用潜在生态风险指数法分析重金属生态风险水平,在相关性分析的基础上采用绝对因子得分-多元线性回归(APCS-MLR)受体模型定量解析重金属污染来源。结果表明:25%样品的镍含量、37.5%样品的镉含量以及12.5%样品的汞含量超过土壤背景值,其余元素均低于土壤背景值;整体区域呈现轻度污染及以下状态,Ni和Hg是重要污染贡献者;土壤整体处于轻度生态风险水平,所有元素属于轻度生态风险水平,Cd是引起风险的主要因子;As、Cd、Cu可能来源于自然成因,Hg可能来源于农业活动;Pb和Ni可能来源于交通活动。

Loss coefficient of nitrogenous non-point source pollution under various precipitation conditions

In this study,calibrations of non-point source(NPS)pollution models are performed based on Black River basin historical real-time runoff data,sedimentation record data,and NPS sources survey information.The concept of NPS loss coefficient for the watershed or the loss coefficients(LC)for simplicity is brought up by examining NPS build-up and migration processes along riverbanks in natural river systems.The historical data is used for determining the nitrogenous NPS loss coefficient for five land use types including farmland,urban land,grassland,shrub land,and forest under different precipitation conditions.The comparison of outputs from Soil and Water Assessment Tool(SWAT)model and coefficient export method showed that both methods could obtain reasonable LC.The high Pearson correlation coefficient(0.94722)between those two sets of calculation results justified the consistency of those two models.Another result in the study is that different combinations of precipitation condition and land use types could significantly affect the calculated loss coefficient.As for the adsorptive nitrogen,the order of impact on LC for different land use types can be sorted as:farm land.urban land.grassland.shrub land.forest while the order was farmland.grass land.shrub land.forest.urban land for soluble nitrogen.

生物碳对除草剂污染的喀斯特坡耕地黄壤生态效应研究

本研究旨在探讨生物碳在喀斯特坡耕地黄壤中对除草剂污染的生态效应,通过田间试验和室内化验相结合的方法,研究生物碳添加对土壤化学特性、生物学特性等黄壤生态效应的影响。结果表明:添加生物碳显著降低黄壤中除草剂的生物有效性,改善土壤营养环境,提升土壤肥力,增加土壤微生物多样性,促进作物生长和降解和吸附除草剂,从而减少除草剂对作物的影响作用。

中国耕地土壤重金属污染概况

依托收集的耕地土壤重金属污染案例资料,建立了我国138个典型区域的耕地土壤重金属污染数据库,并利用《土壤环境质量标准》(GB15618—1995)中的二级标准作为评价标准,测算了我国耕地的土壤重金属污染概况。研究表明:(1)我国耕地的土壤重金属污染概率为16.67%左右,据此推断我国耕地重金属污染的面积占耕地总量的1/6左右;(2)耕地土壤重金属污染等别中,尚清洁、清洁、轻污染、中污染、重污染比重分别为68.12%,15.22%,14.49%,1.45%,0.72%;(3)8种土壤重金属元素中,Cd污染概率为25.20%,远超过其他几种土壤重金属元素;此外,也有一些区域发生Ni,Hg,As和Pb土壤污染,但是Zn、Cr和Cu元素发生污染的概率较小;(4)辽宁、河北、江苏、广东、山西、湖南、河南、贵州、陕西、云南、重庆、新疆、四川和广西14个省、市和自治区可能是我国耕地重金属污染的多发区域,特别是辽宁和山西的耕地土壤重金属污染可能尤其严重。

基于农用地分等和土壤环境质量评价的耕地综合质量评价

该文从耕地生态管护的角度出发,探讨了如何实现土壤环境质量评价与农用地分等成果的融合。基于土壤环境质量评价和农用地分等的理论和方法,该文提出了耕地综合质量评估技术,即在农用地分等所建立的等级体系基础上,引入土壤环境质量评价系数概念,进一步利用该系数对农用地利用等指数进行修订,得到耕地综合评价指数,并以河南省洛阳市为例作了实证研究。根据洛阳市耕地质量综合评价结果,与原农用地利用等别相比,无污染的耕地综合等别保持不变,有污染倾向的耕地综合等别有所下降,存在污染的耕地等别降为末等。这些评价结果可以为土地利用管理、环境污染防治规划将提供更有效的依据。

珠三角丘陵区耕地质量综合评价及指标权重敏感性分析

快速工业化和城市化给珠三角地区的耕地造成一系列土壤环境污染问题,合理评价这些区域耕地质量对指导耕地的有效利用和保护以及实现耕地数量-质量综合平衡与管理具有重要意义。目前耕地质量评价中,较少考虑土壤污染因素,并且缺乏对指标的权重敏感性分析验证评价结果的可靠性。因此该文以珠三角土壤受污染区之一的增城区为例,综合考虑土壤肥力因素以及土壤环境评价指标,从土壤理化性质、农业生产条件、区位条件、土壤环境4个方面构建耕地质量综合评价指标体系,分析增城区耕地质量总体特征及空间布局与行政区域分布规律,在此基础上基于OAT(one-at-a-time)法来评估各指标权重的不确定性对评价结果的影响程度。结果表明:增城区耕地整体质量较高但优质耕地较少。在耕地质量综合评价中融入土壤污染因素,并对其进行微观定量分析,使得评价体系更全面。不同指标权重变化对耕地质量变化率影响的空间差异较大;对于同一指标,权重增加或减少的值相同时,其对耕地质量评价结果的敏感性相同。最大的MACR(mean absolute change rate)值3.558 2%远低于相应的权重变化率30%,表明评价结果总体相对稳定,该文初始确定的权重是合理的。该研究有助于国土相关部门更好地掌握土壤受污染区域的耕地质量,在空间多准则决策中减少不确定性影响。

面源污染、碳排放双重视角下中国耕地利用效率的时空分异

在中国耕地非农化日趋加剧,耕地抛荒、撂荒、低效粗放利用等现象愈演愈烈,耕地污染问题日益突出的背景下,提高耕地利用效率对于促进耕地可持续利用,实现耕地利用与资源环境协调发展具有重要的现实意义。本文采用单元调查评估法及碳排放系数公式对中国耕地利用过程中面源污染和碳排放的产出量进行评估,并使用非期望产出的窗式SBM模型对1993-2013年中国耕地利用效率进行重新估算,进而对耕地利用效率的时空分异特征及改进途径进行分析。主要结论:从时间分异特征来看,中国耕地利用效率呈现出显著下降的变化趋势;种植业大省耕地利用低效率现象逐步增强;投入冗余对耕地利用效率的负作用最大且趋于增强;非期望产出冗余对耕地利用效率的负作用次之且趋于增强;面源污染和碳排放的过量产出与耕地利用效率提升的矛盾日益加剧。从空间分异特征来看,耕地利用高效率地区大幅减少,分布状态由"连片"分布向"点状"分布于东部和西部地区转换;低效率地区以中部地区为中心向东部和西部地区扩张;耕地利用效率呈现出严重的"两级分化"特征。从改进途径来看,中国耕地利用效率的改进潜力主要在减少耕地利用投入冗余和降低非期望产出两个方面。

无锡市耕地毁坏综合鉴定案例研究

研究目的:总结现有耕地毁坏鉴定标准的发展及目前鉴定标准存在的问题与不足,拟从耕地毁坏动力机制入手,建立完善的耕地毁坏程度鉴定标准和综合鉴定方法,以促进此项制度的规范发展。研究方法:采用文献分析法,总结分析现有的研究成果,为建立耕地毁坏指标体系奠定基础,在耕地毁坏的综合鉴定中采用权重指数和法来鉴定耕地的毁坏程度。研究结果:(1)建立的耕地毁坏鉴定指标体系和多种毁坏类型的综合鉴定方法具有可操作性;(2)无锡市新区硕放街道溇金村的耕地毁坏案例的综合鉴定得分为63.1,属于重度毁坏,较难通过治理措施恢复且恢复耕地的成本较难估量。研究结论:建立的耕地毁坏程度鉴定标准和综合鉴定方法,可以为耕地违法案件查处提供依据;由于已有的案件中多种毁坏类型一般是同时存在的,单项鉴定难以准确地反映耕地毁坏的程度,作者提出了耕地毁坏综合鉴定的方法,可为中国相关工作的开展提供参考依据。