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.

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(CIS),the longterm 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 are260017.5,111607.7 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.

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.

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.

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。

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.

耕地规模、细碎化对化肥面源污染的影响

不科学不合理的化肥投入所导致的化肥面源污染问题日益严重,而耕地作为农业生产最基本、最稀缺的资源,耕地规模、耕地细碎化等耕地资源禀赋特征直接制约着农户的化肥投入行为,因此,探究耕地规模、细碎化等耕地资源禀赋特征对化肥面源污染的影响机制,对化肥面源污染治理,促进农业绿色转型和可持续发展有重要意义。本文将耕地规模细分为耕地经营规模与地块规模,从理论上探讨耕地经营规模、地块规模、耕地细碎化三者间的关系及其对化肥面源污染的影响机理,并基于洞庭湖区域595份农户问卷调查数据,利用Tobit模型进行实证检验。研究表明:1)耕地细碎化会增加化肥面源污染,且随耕地细碎化程度加深,会削弱耕地经营规模或地块规模扩大对减少化肥面源污染的正向影响;2)耕地经营规模与化肥面源污染排放强度之间呈“U”型关系,耕地经营规模的扩大有利于削弱耕地细碎化产生的负向影响,加强地块规模扩大对减少化肥面源污染的正向影响;3)地块规模对化肥面源污染有显著削减作用,且地块规模扩大,能削弱耕地细碎化加深产生的负向影响,加强耕地经营规模扩大产生的正向影响。据此,为减少化肥面源污染,应将土地整治与耕地流转相结合,鼓励农户在适度范围内扩大耕地经营规模的同时,推动地块规模的扩大,降低耕地细碎化程度,有效发挥耕地规模效益。

洞庭湖平原化肥面源污染生态环境风险及脱钩效应

[目的]推动实现农业经济增长与化肥面源污染生态环境风险的脱钩,为有效治理耕地面源污染和耕地可持续利用提供理论支持。[方法]基于生态环境风险评价模型,从县域尺度评价洞庭湖平原各地区化肥面源污染生态环境风险程度,采用非参数核密度估计洞庭湖平原化肥面源污染生态环境风险区域差异,进而采用脱钩模型进一步分析了洞庭湖平原农业经济增长与耕地化肥面源污染生态环境风险的脱钩关系。[结果](1)2009—2019年洞庭湖平原化肥面源污染生态环境风险指数呈现先升后降的趋势,化肥面源污染生态环境风险指数先由2009年的0.749升至2014年的0.762,然后降至2019年的0.732,经历了由中度风险转为高度风险,后又降为中度风险的过程;中部地区污染更严重;(2)化肥面源污染生态环境风险区域差异明显,呈现两极分散化集聚特征,内部差距先扩大后缩小;(3)洞庭湖平原农业经济增长与化肥面源污染生态环境风险的脱钩关系呈现出明显的阶段性特征:第一阶段为波动期(2009—2013年),第二阶段为强脱钩期(2014—2019年)。[结论]在面源污染治理工作的推进下,洞庭湖平原化肥面源污染生态环境风险经历了先上升后下降的变化趋势,且呈现出明显的区域分异,基本实现与农业经济增长的稳定脱钩,整体呈现出绿色可持续发展趋势。

环鄱阳湖城市群耕地面源污染时空演变研究

为提供合理的区域环境和耕地可持续发展的理论依据,研究2005-2020年环鄱阳湖城市群耕地化学需氧量(COD)、总氮(TN)、总磷(TP)面源污染的时空演变特征。结果表明:(1)时间上看,环鄱阳湖城市群COD、TN排放总量分别由2005年的50.56万、13.51万t下降至2020年的46.14万、13.26万t,而TP排放总量由2.65万t增加至2.74万t;COD排放强度由2005年的258.22 kg/hm^(2)下降至2020年的248.97 kg/hm^(2),而TN、TP排放强度分别由69.00、13.53 kg/hm^(2)增加至71.55、14.79 kg/hm^(2)。3类指标的主要污染源均是畜禽养殖。(2)空间上看,耕地面源污染程度高的地方主要集中在西南部地区、南昌市区及崇仁县,污染程度较低的地方主要分布在北部和东部地区。

南水北调中线工程水源区耕地面源污染治理农户参与意愿研究--以南阳市为例

南水北调中线工程水源区耕地面源污染治理不仅要依靠先进的科学技术,还需要农户的积极参与。采用TPB理论构建水源区耕地面源污染治理农户参与意愿理论分析框架,剖析农户参与意愿的影响因素并提出研究假说;构建结构方程模型,利用问卷调研收集数据,对水源区耕地面源污染治理农户参与意愿进行实证检验。研究结果表明,水源区耕地面源污染治理农户参与意愿较高,行为态度、主观规范、知觉行为控制等潜变量对农户参与意愿均存在正向影响,且潜变量之间也存在相关关系。因此,建议加大水源区耕地面源污染治理重要性的宣传力度,提升农户对于耕地面源污染的认知程度,增加农户的经济收入,增强地方政府的支持力度,多渠道提升水源区耕地面源污染治理的农户参与意愿。

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。

坡耕地不同物种植物篱对面源污染物的拦截效率及影响因素

在红枫湖上游15°的坡耕地上设置30个植物篱径流小区,小区水平投影面积100 m2,顺坡长20 m,横坡宽5 m。在小区内横坡等距种植三带植物篱,植物篱带呈双行"品"字型种植模式,带长5 m,带宽0.15 m。通过监测该年度天然降雨下每个径流小区产生的地表径流、泥沙和养分情况,探讨了在相同种植模式下9种不同物种植物篱对坡耕地面源污染物的拦截效率及其影响因素。结果表明:灰毛豆植物篱截流效应最佳,相对径流拦截率为91.75%;紫花苜蓿植物篱减沙效应最佳,相对泥沙拦截率为69.25%。灰毛豆植物篱能更有效地抑制湖泊水体氮、磷元素的富集进程,其中,对坡耕地氮相对拦截量为283.03 g·hm-2,相对拦截率为70.08%;对坡耕地磷相对拦截量为185.92 g·hm-2,相对拦截率为80.21%。胡枝子植物篱能更有效地抑制湖泊水体钾元素的富集进程,对坡耕地钾相对拦截量为135.11 g·hm-2,相对拦截率为86.08%;灰毛豆次之,对坡耕地钾相对拦截量为125.13 g·hm-2,相对拦截率为79.72%。

不同耕作模式下稻田生态系统对田面水中无机态氮的消纳

稻田生态系统可以有效减少流入水体的农业面源污染物.本文通过模拟试验,研究了不同施肥时间(常规施肥时间和在此基础上提前一个半月施肥)以及在不同耕作模式(垄作、平作)下稻田生态系统对田面水中无机态氮的消纳效果.结果表明:稻田生态系统能够有效降低田面水中无机态氮、全磷的含量.与灌水第1d相比,灌水14d后,所有稻田田面水中NH4+-N浓度平均下降84.3%,灌水21d后,所有稻田田面水中NO3--N浓度平均下降64.6%,TP浓度下降58.0%;提前施肥条件下稻田生态系统对田面水中无机态氮具有更好的吸附、消纳效果,灌水后的第1d,所有稻田田面水中NH4+-N浓度均出现最高值,其中,常规时间施肥和提前施肥NH4+-N质量体积浓度分别为2.52和1.28mg/L,灌水后的第3d,常规时间施肥稻田田面水中NO3--N质量体积浓度上升至最大值5.92mg/L,而此时提前施肥稻田约为3.65mg/L;不同耕作模式对无机态氮消纳的影响差异不显著.

洞庭湖平原耕地面源污染时空特征及脱钩效应

[目的]揭示2009—2019年洞庭湖平原耕地面源污染时空演变规律,探究耕地面源污染与农业生产的脱钩关系,为洞庭湖平原耕地面源污染治理提供科学参考。[方法]采用化肥农药施用强度和粮食单产分别描述洞庭湖平原耕地面源污染和农业生产状况,利用空间分析法和脱钩模型揭示2009—2019年洞庭湖平原耕地面源污染和农业生产的时空演变规律及其脱钩关系。[结果](1)2009—2019年洞庭湖平原化肥、农药施用强度均呈现“先升后降”的趋势,且具有明显的空间差异性,化肥、农药生产率总体上呈现出上升趋势;(2)2009—2019年洞庭湖平原粮食单产呈现出倒U形趋势,且具有明显的空间差异性;(3)洞庭湖平原粮食单产与化肥农药施用强度的脱钩关系呈现出明显的阶段性特征:第一阶段为波动期(2009—2013年),第二阶段为强脱钩期(2014—2015年),第三阶段为弱负脱钩和衰退脱钩期(2016—2019年);(4)洞庭湖平原农业生产与耕地面源污染的脱钩关系在县级空间尺度上逐渐呈现出较高的趋同性和聚集特征。[结论]应进一步加强耕地面源污染源头防治,并采取多种举措提高粮食单产,最终实现耕地面源污染与农业生产的强脱钩。

耕地面源污染治理农户参与意愿研究

为了分析农户参与耕地面源污染治理的意愿及其影响因素,首先采用计划行为理论从理论上分析了农户参与耕地面源污染治理的行为机理,然后利用洞庭湖平原农户调查数据,运用结构方程模型进行实证检验。结果表明:(1)农户对耕地面源污染治理的参与意愿不高;(2)行为态度、主观规范和知觉行为控制对农户参与耕地面源污染治理的意愿均有正向影响;(3)农户对化肥危害、农药危害、有机肥改善环境的认知程度对其行为态度有显著正向影响;(4)邻居、媒体、村委会影响程度对农户主观规范有显著正向影响;(5)农户的经济实力、行为能力和专业素质对其知觉行为控制有显著正向影响。因此,应切实增强农户治理耕地面源污染的主体意识,充分发挥基层村民自治组织在耕地面源污染治理中的作用,同时采用经济手段引导和激励农户参与耕地面源污染治理。

基于UTAUT模型的耕地面源污染治理生态补偿农户受偿意愿研究

为了有效提高农户参与耕地面源污染治理的主动性和积极性,基于洞庭湖平原农户问卷调查数据,以整合型技术接受与使用(UTAUT)模型为理论分析框架,运用CVM与Heckman两阶段模型,探索农户参与耕地面源污染治理的受偿意愿及其影响因素。结果表明:在政府给予相应生态补偿的情况下,调查区域内同意以减施农药化肥方式参与耕地面源污染治理的农户有77.34%;非参数估计法测算出农户的受偿意愿水平为2094.45元·hm^(-2)·a^(-1),而Heckman两阶段估计方法计算结果为1764.34元·hm^(-2)·a^(-1),二者可分别作为洞庭湖平原耕地面源污染治理生态补偿标准上、下限的参考值;经济绩效期望、经济能力、公共关系、技术便利性和政策便利性等因素对农户参与耕地面源污染治理生态补偿的受偿意愿具有正向影响,而社会因素负向影响着农户受偿意愿。因此,政府部门应结合当地实际尽快制定科学合理的农户生态补偿政策,促进农户受偿意愿的提高,并增强社会因素在耕地面源污染治理中的引领作用,引导农户树立治理耕地面源污染的主体意识,促进耕地可持续利用。

基于熵权-集对模型的耕地面源污染生态风险评价与防控——以新疆昌吉州为例

为构建以化肥、农药、农膜为主要风险源的生态风险评价与防控模型,基于熵权-集对分析模型尝试评价新疆昌吉州不同县市空间区域耕地面源污染风险等级异质性。结果表明,2004-2017年昌吉州化肥施用总量、农药使用总量和农膜使用总量逐年大幅增加,呈现未来增长态势。耕地质量等别年度监测数据的样本调查结果显示,土壤理化性质、质地、结构等多项指标均呈现不同程度的恶化。昌吉州耕地面源污染的生态风险强度区空间上主要分布于昌吉州西部的昌吉市、呼图壁县和玛纳斯县,生态风险中度区主要分布于昌吉州中部的阜康市、吉木萨尔县,生态风险轻度区主要分布于昌吉州最东部的奇台县和木垒哈萨克自治县。研究表明,新疆昌吉州耕地面源污染存在空间格局的生态风险异质性,呈现东、中、西污染聚集且由西向东依次减轻的空间分布规律,耕地面源污染的生态风险与区域产业经济发展、农民传统耕作方式、水文地质条件、地理位置、周边环境基础状况等因素相关。基于此,运用Bow-Tie模型构建了耕地面源污染生态风险的防控与差异化治理体系。

耕地面源污染的生态风险评价指标体系探讨与防控——以新疆昌吉州为例

基于化肥、农药、农膜为主要风险源的耕地面源污染发展态势,探讨干旱半干旱地区耕地面源污染的生态风险评价指标体系,运用熵权TOPSIS模型评估昌吉州不同县市耕地面源污染的空间格局分布的等级异质性。研究结果表明,时序上,新疆昌吉州耕地面源污染的化肥、农药、农膜的使用量10年整体呈现递增态势;空间上,昌吉州耕地面源污染生态风险空间格局存在等级异质性,地域特点为连片抱团聚集,东西两极分化,反映了"东高西低""南高北低"的空间风险分布规律;探究形成机理与影响因素,耕地面源污染的生态风险强弱与区域社会经济发展、农民生产生活方式、水文地理条件、生态环境基础状况等因素关系密切。基于此,为打好耕地面源污染污染防治攻坚战,防范化解因农产品质量安全引发的重大社会风险,针对性地提出防控对策与差异化治理措施。