农用化学物质对环境的影响及对策

农用化学物质主要是指化肥、农药和农膜。农用化学物质在农业生产中对增加农产品产量起到了巨大的作用,但由于使用过量、不合理使用以及农用化学物质本身结构的原因引起了一系列环境问题,严重地影响了人类的生存环境和人类的健康。本文概述了农用化学物质的种类及农用化学物质对水体、土壤、大气及农产品的影响,并在借鉴国外先进经验的基础上,结合我国的实际情况,提出了6项防治措施。     

近50年福建省年度极端最低气温统计特征

把福建省各台站年度极端最低气温统一订正为1950／1951～1999／2000整50年记录,并对其进行标准化处理和评价,继而对其偏冷年景进行特征分析。近50年福建省年度极端最低气温1954／1955为最冷年,1999／2000为第3冷年;冬季月平均气温正常,仍可出现异常或明显偏冷的低温;全省年度极端最低气温年景评价为异常偏冷,有的台站年景却仍属正常,年景等级相差达4级。全省年度极端最低气温的年景评价为异常或明显偏低,该年度福建省果树、花卉和其它冬季作物必然遭受不同程度的冻害和寒害。     

四川省土壤元素含量和生态农业地质研究

论述了四川省土壤元素含量和农作物优质高产与土壤环境中化学元素N、P、K、S、Fe、Mn、Cu、Zn、B、Mo、V、Sr、Ti、Mg、La、Ce、Pr、Nd、Sm、Eu、Y、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Ca、Co、Ni、F、F、Tl、Si、Na、Cr、Pb、Cd、Hg、Se、Ba、Te、Ta有密切的关系。提出了生态农业地质研究的目的、内容、方法、管理及其前景。     

Comprehensive evaluation on agricultural environment in western China

Introduction Western China is vast in area with different landforms and ecosystems, and its environment is deteriorated with different agricultural productivities. The northwestern region is very drought for lack of rainfall, and desertification there is serious with difficulty in vegetation restoration, while in the southwestern region the land is fragile, vegetation is degraded and water and soil loss serious. Even worse, for the lack of effective management, new environmental problems deriv…     

基于多源遥感数据的甘肃省农业干旱研究

干旱是农作物生长发育的主要环境胁迫因子,也是制约农业丰产丰收的关键自然要素。农业干旱监测通常基于气象站点观测数据,这在一定程度上难以反映区域尺度的农业干旱状况。以甘肃省为研究区,基于MODIS、TRMM、ESA CCI等遥感数据产品和气象站点数据,利用随机森林回归模型构建综合气象干旱指数（CMDI）,并对甘肃省2011—2019年农作物生长季（4—9月）旱情时空格局及变化规律进行分析。结果表明：（1）CMDI与实测值的决定系数（R2）在各月均高于0.634,且与标准化降水蒸散发指数（SPEI）在空间上具有一定的相关性,表明该指数可反映农业干旱的发生发展过程。（2）甘肃省农业干旱呈现明显的地域分异规律,干旱程度由东南向西北逐渐加重,其中河西地区多为特旱区和重旱区,陇中地区为重（中）旱区,陇南、陇东、甘南地区为干旱-无旱波动变化区。（3）2011—2019年甘肃省农业干旱在年、月尺度上均呈现较大的波动趋势,其中2012年干旱程度最轻,2017年则最为严重;甘肃省大部分地区在4月和6月,陇东、陇南地区分别在5月和9月以及甘南地区4—9月农业旱情有所减轻外,其余地区在农作物生长季的旱情呈加重趋...     

太湖上游流域农业土地的氮剩余及其对湖泊富营养化的影响

太湖上游流域农业土地中氮的剩余对太湖的富营养化具有至关重要的影响．利用2002年各乡镇的农业统计资料,对上游流域农业土地中氮的剩余量进行计算．计算结果表明,上游流域农业土地中氮的剩余总量为134．8×103t/a,单位农业土地面积的剩余量为178．9 kg/(hm2·a)．从单位面积氮剩余量的空间变化看,东、西苕溪流域的剩余量较低,而其它流域的剩余量相对较高．借助典型区域氮剩余的长系列计算数据,对上游地区氮剩余的长期变化规律进行分析．并在此基础上,探讨太湖的富营养化演变趋势与氮剩余长期变化的关系．     

新时期伊朗农业特征与中伊农业合作前景初探

进入21世纪以来,中国伊朗政治关系更加密切,经贸关系发展迅速,但在农业领域的合作极少。本文阐述了伊朗农业生产现状特征;分析了中伊双方农业合作的有利因素和不利因素及其存在的问题;论证了中伊农业合作的可行性;指出了中伊农业合作的广阔前景。最后,根据伊朗农业的具体情况和有关政策,就中国和伊朗农业合作的方式和重点领域提出了建议。     

MODELLING THE IMPACT OF LAND USE CHANGE ON WATER QUALITY IN AGRICULTURAL CATCHMENTS

Export coefficient modelling was used to model the impact of agriculture on nitrogen and phosphorus loading on the surface waters of two contrasting agricultural catchments. The model was originally developed for the Windrush catchment where the highly reactive Jurassic limestone aquifer underlying the catchment is well connected to the surface drainage network, allowing the system to be modelled using uniform export coefficients for each nutrient source in the catchment, regardless of proximity to the surface drainage network. In the Slapton catchment, the hydrological pathways are dominated by surface and lateral shallow subsurface flow, requiring modification of the export coefficient model to incorporate a distance–decay component in the export coefficients. The modified model was calibrated against observed total nitrogen and total phosphorus loads delivered to Slapton Ley from inflowing streams in its catchment. Sensitivity analysis was conducted to isolate the key controls on nutrient export in the modified model. The model was validated against long-term records of water quality, and was found to be accurate in its predictions and sensitive to both temporal and spatial changes in agricultural practice in the catchment. The model was then used to forecast the potential reduction in nutrient loading on Slapton Ley associated with a range of catchment management strategies. The best practicable environmental option (BPEO) was found to be spatial redistribution of high nutrient export risk sources to areas of the catchment with the greatest intrinsic nutrient retention capacity. © 1997 by John Wiley & Sons, Ltd.     

The potential for reference site resampling in estimating sediment redistribution and assessing landscape stability by the caesium-137 method

The objective of this study was to examine a new resampling methodology for estimating reference levels of ¹³⁷Cs in uneroded locations. Accurate and precise measurement of ¹³⁷Cs is required from reference locations to estimate long-term (c. 40 years) sediment redistribution (SRD) and landscape stability. Without reliable long-term, quantitative erosion data it is extremely difficult for land managers to make optimal decisions to ensure landscape sustainability. To determine the influence of ¹³⁷Cs reference site sampling, particularly under-sampling, on SRD and landscape stability, two statistical approaches were applied to a grid-based data set. Caesium-137 inventories in the reference location (n=36) indicated that data were normally distributed, with a mean inventory of 2150±130 Bq m⁻² (±95% confidence band) and a coefficient of variation of 18%. The two approaches used to determine the effect of under sampling included: (1) one-time random subsampling from the total sample collected, subsamples ranged from n=3 to n=30; from these data means and parametric confidence bands were calculated; and (2) random subsamples (n=3 to n=36) were selected from the total ¹³⁷Cs reference sample, and each subsample was in turn resampled 1000 times with replacement to establish a sampling distribution of means. Thus, an empirically derived mean and 95% confidence bands were established. Caesium-137 activities determined from each approach were input into equations to estimate SRD from two cultivated fields. Results indicate that the one-time random sampling approach for subsamples of size ≤12 significantly over- or under-estimated net SRD, particularly from the gently sloping agricultural field. Computer-intensive resampling produced significantly better estimates of net SRD when compared with the random one-sample approach, especially when a subsample of size three was used. Landscape stability, based on partitioning the agricultural fields into areas exhibiting erosion, stability and deposition, was better approximated for both fields by applying resampling. © 1998 John Wiley & Sons, Ltd.     

农业旅游活动对岩溶地区土壤微生物群落结构的影响——以重庆市铜梁区黄桷门奇彩梦园为例

开展农业旅游活动对土壤生态环境影响的专题研究,可为休闲农业旅游区的合理开发和有效保护提供理论基础,为评估未来农业旅游活动对环境的影响提供科学依据.本文以重庆市铜梁区黄桷门奇彩梦园为例,通过对游步道两侧的土壤进行调查采样,并运用磷脂脂肪酸(PLFAs)谱图分析法,研究了土壤微生物群落组成、受农业旅游活动影响的距离及其受冲击程度.结果显示:微生物群落结构受冲击范围在4 m以内(p<0.01),微生物生物量在土壤中的分布随着离游径的距离变小而明显下降趋势;在受农业旅游活动冲击的范围内细菌、革兰氏阳性细菌、革兰氏阴性菌、真菌的生物量随着离游径的距离变小而明显下降,放线菌在部分样区表现出该规律,原生动物无此规律;对所测PLFAs数据进行多样性和冲击指数分析后得出假单胞菌(16∶0)受影响程度最大,节杆菌(17∶0)受影响程度最小,受冲击程度大小与该微生物在生物总量中所占的比重呈正相关;农业旅游活动对土壤微生物群落结构造成了破坏,土壤生态系统的稳定性已受到冲击.