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931.
William Hartley Nicholas M. Dickinson Nicholas W. Lepp 《Environmental pollution (Barking, Essex : 1987)》2009,157(10):2654-2662
Degraded land that is historically contaminated from different sources of industrial waste provides an opportunity for conversion to bioenergy fuel production and also to increase sequestration of carbon in soil through organic amendments. In pot experiments, As mobility was investigated in three different brownfield soils amended with green waste compost (GWC, 30% v/v) or biochar (BC, 20% v/v), planted with Miscanthus. Using GWC improved crop yield but had little effect on foliar As uptake, although the proportion of As transferred from roots to foliage differed considerably between the three soils. It also increased dissolved carbon concentrations in soil pore water that influenced Fe and As mobility. Effects of BC were less pronounced, but the impacts of both amendments on SOC, Fe, P and pH are likely to be critical in the context of As leaching to ground water. Growing Miscanthus had no measurable effect on As mobility. 相似文献
932.
考察沸石粉投加对活性污泥增殖及脱氨氮动力学的影响,并根据相关结论探讨了不同泥龄(SRT)条件下沸石粉的生物再生情况。结果表明,曝气池中投加沸石粉可明显提高活性污泥的产率系数和衰减系数。与传统活性污泥法相比,投加沸石粉的试验组稳定运行后,污泥产率系数和衰减系数分别提高12.5%和16.7%;当泥龄≤10 d时,出水氨氮去除率提高10%~37%,继续增加泥龄,氨氮去除率提高不明显。通过对比试验结果的关联性分析,认为在低浓度条件下,沸石中铵离子的解吸速率是沸石生物再生的限制步骤,而且再生速率与泥龄呈正相关对应关系。 相似文献
933.
近50年辽宁省作物生长季气候条件变化及对农业生产的影响 总被引:8,自引:0,他引:8
利用辽宁省35个气象观测站点1956-2005年的逐月地面观测资料,对辽宁省近50年的农业气候条件的长期变化情况和空间分布特征进行了详细的分析,并初步分析了农业气候条件的变化对农业生产的影响。结果表明:近50年辽宁省生长季(4-9月)日照时数明显减少,每10年减少29.4 h;生长季日照百分率减少也很明显,平均每10年减少1.2%;生长季降水量呈微弱的减少趋势,蒸发量明显减少,平均每10年减少17.3 mm。潜在蒸发量也呈明显的减少趋势。生长季≥10℃界限温度的积温值在近50年明显增加,且全省≥10℃界限温度开始的日期明显提前,大部分地区近50年提前6 d左右。辽宁省生长季3 350℃积温等值线在最近的10年里有明显的北移和东移。 相似文献
934.
Mingliang Liu Hanqin Tian Guangsheng Chen Wei Ren Chi Zhang Jiyuan Liu 《Journal of the American Water Resources Association》2008,44(5):1193-1207
Abstract: China has experienced a rapid land‐use/cover change (LUCC) during the 20th Century, and this process is expected to continue in the future. How LUCC has affected water resources across China, however, remains uncertain due to the complexity of LUCC‐water interactions. In this study, we used an integrated Dynamic Land Ecosystem Model (DLEM) in conjunction with spatial data of LUCC to estimate the LUCC effects on the magnitude, spatial and temporal variations of evapotranspiration (ET), runoff, and water yield across China. Through comparisons of DLEM results with other model simulations, field observations, and river discharge data, we found that DLEM model can adequately catch the spatial and seasonal patterns of hydrological processes. Our simulation results demonstrate that LUCC led to substantial changes in ET, runoff, and water yield in most of the China’s river basins during the 20th Century. The temporal and spatial patterns varied significantly across China. The largest change occurred during the second half century when almost all of the river basins had a decreasing trend in ET and an increasing trend in water yield and runoff, in contrast to the inclinations of ET and declinations of water yield in major river basins, such as Pearl river basin, Yangtze river basin, and Yellow river basin during the first half century. The increased water yield and runoff indicated alleviated water deficiency in China in the late 20th Century, but the increased peak flow might make the runoff difficult to be held by reservoirs. The continuously increasing ET and decreasing water yield in Continental river basin, Southwest river basin, and Songhua and Liaohe river basin implied regional water deficiency. Our study in China indicates that deforestation averagely increased ET by 138 mm/year but decreased water yield by the same amount and that reforestation averagely decreased ET by 422 mm/year since most of deforested land was converted to paddy land or irrigated cropland. In China, cropland‐related land transformation is the dominant anthropogenic force affecting water resources during the 20th Century. On national average, cropland expansion was estimated to increase ET by 182 mm/year while cropland abandonment decreased ET by 379 mm/year. Our simulation results indicate that urban sprawl generally decreased ET and increased water yield. Cropland managements (fertilization and irrigation) significantly increased ET by 98 mm/year. To better understand LUCC effects on China’s water resources, it is needed to take into account the interactions of LUCC with other environmental changes such as climate and atmospheric composition. 相似文献
935.
持续10a的田间试验结果表明,在保持农业系统养分循环再利用的基础上,根据土壤养分供给力设计化肥施用量,可以在实现作物高产的同时,平衡土壤养分收支,从而避免土壤中肥料养分(主要是氮)过剩而进入环境。 相似文献
936.
陈小勇 《生态与农村环境学报》1998,(4)
转基因逃逸是伴随着工程作物释放的一种风险。本文首先分析了转基因逃逸的途径,并讨论了影响转基因逃逸的因素,对我国主要农作物中逃逸风险进行了初步评价,一些农作物中存在较大的转基因逃逸风险,最后探讨了避免和减小逃逸风险的措施。 相似文献
937.
Methane emissions from ricefields as affected by organic amendment, water regime, crop establishment, and rice cultivar 总被引:1,自引:0,他引:1
B. Wang Y. Xu Z. Wang Z. Li Y. Guo K. Shao Z. Chen 《Environmental monitoring and assessment》1999,57(2):213-228
Methane fluxes from Beijing ricefields as affected by organic amendment, water regime, crop establishment method, and rice cultivar were measured with a closed chamber method in 1990, 1991, 1995, and 1996. Total fluxes from plots receiving high organic amendment always exceeded those from the low-input plots. Compared with continuous flooding, intermittent irrigation (there were a few days of no standing water between two irrigations) and constant moisture (the field had no standing water, but remained saturated) reduced methane emission rate by 25.4 and 58.4%, respectively. Methane flux from a dry-seeded rice field was 75.2% lower than from a transplanted ricefield although both dry-seeded rice plots and transplanted ricefields were initially flooded at the same time. Rice cultivars differed in methane emission rates by 9.0–55.7%. Emission rates were positively correlated with aboveground dry matter production and root weight, but not grain yield. Intermittent irrigation and rice cultivar seem to be the most promising methods for mitigating methane emission from ricefields; they do not affect rice yield and are easily implemented at the farm level. 相似文献
938.
939.
太湖流域种植业肥料施用强度普遍较高,且以化学肥料为主要形态.因肥料投入不适宜,种植业氮、磷流失问题显著.2015年以来,各地区积极对种植业肥料施用策略进行调整,但当前工作主要基于粮食作物系统且仍停留在化肥施用总量削减和有机肥施用面积提升层面上,缺少菜地、果园、茶园作物系统的相关数据以及对农业环境问题的响应.对此,以苏州市吴中区为太湖流域典型农区代表,研究2019~2021年稻田、菜地、果园和茶园这4类作物系统肥料策略调整对氮、磷流失的影响.结果表明,肥料源养分投入强度的调控是决定氮、磷流失的关键;适宜的有机肥替代比例有助于降低氮、磷流失风险,但有机肥施用需考虑时机并尽可能搭配农用机械.肥料效率是兼顾农业生产过程环境友好、生产主体经济效益的核心,也是后期肥料施用策略调整的导向.稻田系统的肥料施用策略调整应重视养分中不同元素配比,菜地系统应以种植结构调整为抓手,茶园、果园系统可从复合系统视角制定同时满足茶、果生长的施肥策略,助力构建满足农业绿色发展需求的作物系统. 相似文献
940.
基于2017—2021年MODIS、VIIRS和Himawari-8等多套卫星的火点辐射能量(FRE)和云量反演数据,使用更高分辨率的火点替代相邻位置低分辨率火点的融合方法,利用晴空的火点分布数据对被云遮蔽的区域进行补偿,核算得到了2 km高分辨率的广西秸秆露天燃烧排放数据,并针对2017—2021年的广西秸秆露天燃烧排放量展开精细的时空分布研究。结果表明:2017—2021年广西秸秆露天燃烧的CO、NOx、SO2、NH3、VOCs、PM10和PM2.5的年排放量均值分别为12.91万、0.78万、0.16万、0.17万、2.77万、2.26万、2.21万t,排放高值区域分布在广西中部及西南部。秸秆露天燃烧排放的主要时间集中在冬、春季节(10月至次年3月),时值晚稻收割期和甘蔗榨季,占全年排放量的60%以上。广西秸秆露天燃烧PM2.5年均排放量是全广西PM2.5人为源年排放量的8.74%,通过逐日排放贡献分析发现,秸秆露天燃烧具有短期排放量较大的特点,2017—2021年,在1—2月有34 d出现秸秆露天燃烧导致PM2.5排放量超过人为源排放量50%的情况。 相似文献