Cadmium uptake by different rice genotypes that produce white or dark grains

IntroductionCadmium(Cd)isanon essentialtracemetalthathasadverseeffectsonplants,animalsandhumans.EnvironmentalcontaminationwithCdduetoanthropogenicactivities,suchasmining,industry,agricultureandwastedisposalhasbeenincreasingsincethebeginningofthe 2 0thcentury (Alloway,1995) .ResearchoncontrollingCdpollutionassociatedwithassessingandmanagingacuteinjurytohumanhealththroughoccupationalexposureanddisposalofCdfromindustrialpointsourcestolocalpopulationsthroughseveralpathwayshasmadeconsiderableadva…     

Explaining support for renewable energy: commitments to self-sufficiency and communion

ABSTRACT

Across the political spectrum, people favour renewable energy. For political liberals, this support has been attributed to concern for the environment; in contrast, the bases of conservatives’ support are less clear. Derived from interviews with a diverse sample of households in Washington State, USA, and a vignette experiment with a representative sample of American households, results show that Democrats (liberals) and Republicans (conservatives) have different moral intuitions, with Democrats emphasizing communion and both Democrats and Republicans valuing self-sufficiency. These findings explain how politically polarized environmental attitudes can exist alongside a shared support for renewable energy. The study therefore contributes to the literature on environmental concern and behaviour, and has implications for policies aimed at increasing adoption of renewable energy as well as pro-environmental behaviour more broadly.     

面向粮食产量空间化的多元回归分析模型中的两个关键问题探讨

为比较不同区域尺度变量对模型拟合效果的影响,在全国不分区和分区两种情况下,分别基于县级和地市级两个区域尺度上的样本构建粮食产量与水田、水浇地、旱地面积之间的多元线性回归模型,结果显示,用地市级数据作分析样本比用县级数据作分析样本好,分区建模比不分区建模效果好。因此,将全国划分为7个区,以地市级数据作为区域尺度的变量,在区域、栅格、亚栅格三个尺度上探讨变量（因变量、自变量）尺度和常数项取值这两个因素对模型应用的影响。得到以下结论：1）基于区域尺度样本构建的多元回归模型,如果常数项不为0,则不能用于空间化计算;如果常数项为0,则可以用于空间化计算;2）基于栅格尺度样本构建的多元回归模型,不论常数项是否为0,均可应用于空间化计算;3）基于亚栅格尺度样本构建的多元回归模型,不论其常数项是否为0,也均可用于空间化计算,但需要将计算结果乘以一个系数,该系数等于栅格单元面积与亚栅格单元面积的比值。上述结论对其他类型的统计数据空间化具有指导和参考价值。     

Empirical analysis on the influence of the Shaanxi fruit industry on regional food security

As part of its development policy to relieve rural poverty in west China, the Chinese government has introduced measures such as agricultural tax exemptions, agricultural subsidies, and scientific, technological and restructuring improvements to agriculture. Following these actions, farmers’ incomes have increased greatly and the economy in poor areas of west China has seen rapid improvements. However, agricultural restructuring, infrastructure construction and ecological restoration projects have reduced the area of land under arable farming, restricting opportunities for increasing total grain yield. Regional food security is therefore threatened and an imbalance between economic development and food security is created. Shaanxi is a representative province in west China where agricultural restructuring has resulted in large areas of arable land being converted into orchards that produce higher economic returns. This study randomly surveyed 1430 farm households in three counties in the apple-producing region of Shaanxi Province (Luochuan, Changwu and Baishui). The standard of living and household income of farmers in the fruit production areas were higher than in grain-producing areas, thus discouraging grain production. Land under agriculture in the counties studied comprised 59% orchards and 39% arable, with 2% under other uses. Per capita, 204.3 kg of grain was produced, 51% of that required for self-sufficiency. Other staple foods produced amounted to only 13.9% of that needed for self-sufficiency. As a result, nearly half of the grain needed by the community was purchased from outside, resulting in very poor regional food security. Clearly, fruit production in this region seriously affects regional food security. Coordination of relationships between rural economic development and regional food security is key for sustainable development of the regional agriculture and economy of west China.     

惠阳城区降雨径流重金属污染特征研究：Ⅰ.地表堆积物重金属含量分析

以惠阳城区为研究对象,选取4种具有代表性的典型城市功能区类型:工业区、商业区、住宅区、交通区,对其地表堆积物进行样品采集和实验分析.结果表明:地表堆积物细粒部分(粒径<149舯)所占比例为51%,粗粒部分(粒径>2 000um,)所占比例仅4.1%;重金属含量的粒径分级特性和质量分数相似,即粒径越细的部分重金属含量越高;Pb,Zn,Cu.Cr之间的相关系数较高;重金属的浸出浓度在不同的功能区基本遵循同样的规律,即细粒部分重金属浸出浓度最高,随粒径的增大浸出浓度逐减,细粒部分重金属的浸出浓度:w(Pb)为59.1 rag/kg/kg,w(Zn)为93.5 mg/kg,w(Cu)为37.7 ms/ks,w(Cr)为23.9 ms/kg,w(Cd)为0.07 mg,kg.     

废旧电路板的解离特性分析

废旧电路板的回收方法依赖于电路板的性质,因此从定性和定量的角度确定废旧电路板上各种物质的组成和含量,对处理技术的选择非常重要。本论文主要针对目前数量最多的废旧电路板（PCB）,利用选矿技术的分离方法进行废旧电路板的解离特性研究。即破碎后的物料首先通过筛分试验确定物料的粒级组成;通过小浮沉试验确定每个粒级的金属和非金属含量。为后续分选作业的可行性提供依据。     

末次间冰期以来渭河盆地沉积相变化及其影响

渭河盆地南依秦岭、北邻黄土高原,保存了巨厚的风尘河湖相沉积序列,是研究新生代气候环境演化的理想场所.以位于西安凹陷区域的西安市鄠邑区正庄村获取的14 m钻孔岩心作为研究对象,通过与邻近的渭南黄土剖面粒度曲线和全球LR04深海氧同位素曲线对比,构建了岩心序列的年代标尺,利用粒度、磁化率等指标探讨风尘-湖相沉积对风力和水动力的不同响应.对粒度测试结果采用威布尔分布(Weibull-distribution)拟合方法,提取了4个粒度组分指示不同沉积相及变化,结果表明:(1)西安凹陷鄠邑地区在末次间冰期结束时发生了一次沉积相变,由湖泊沉积转向风成沉积;(2)尽管沉积相发生变化,粒度指标对沉积环境变化响应仍然敏感,与黄土和石笋记录可良好对比,揭示出末次间冰期以来渭河盆地沉积环境的显著变化.     

中国粮食主产区耕地撂荒程度及其对粮食产量的影响

耕地撂荒严重地影响着我国的粮食安全。以我国粮食主产区为研究区域,在识别撂荒地分布的基础上,测度了撂荒地空间分布格局,并建立耕地撂荒中介效应模型,探究了耕地撂荒对区域粮食产量的影响机制。结果表明：（1）中国粮食主产区耕地撂荒规模为405.53万hm²,撂荒率约为5.85%;空间上撂荒地规模分布呈“T”字形空间格局,黑龙江东北部、吉林西北部以及内蒙古南部地区为撂荒地主要集聚区。（2）耕地撂荒对于粮食主产区粮食产量具有显著负向影响,2017年我国粮食主产区因耕地撂荒损失的农田生产潜力达到1339.15万t,损失的粮食产量高达2265.6万t,损失比例达4.69%;内蒙古自治区成为粮食产出损失量和损失比例最大的地区。（3）粮食播种面积、农田生产潜力和农业技术投入均发挥了部分中介作用,系数分别为-0.194、-0.025和0.006。（4）应遵从城乡融合以及农业农村发展态势,强化粮食主产区农业生产现代要素投入与政策扶植,构建粮食生产—耕地休耕空间转换弹性机制,保障我国粮食安全。     

中国生猪耗粮系数时空演变特征

当代中国,生猪饲料粮的生产与消费已经逐渐成为影响我国粮食安全保障的重要问题。耗粮系数是合理测算饲料粮需求量的核心,厘清其时空演变特征对准确测算饲料粮数量具有重要意义。通过着重测算2000—2018年中国不同规模饲养生猪耗粮系数,探讨其时空演变特征及可能原因,得到以下主要结论：（1）近年来我国生猪耗粮系数呈现出明显的上升趋势,由2000年的2.39上升至2018年的2.76,年均增长0.023。（2）不同规模饲养生猪耗粮系数的差距逐渐缩小,主要受到饲养过程中使用的精饲料占比变化趋同的影响。（3）大规模饲养生猪的粮食转化效率和时间效率均高于其他规模。（4）散养生猪的耗粮系数在空间上呈现“南北高,中部低”,其他规模则呈现“北高南低,中部高东西低”的格局。从提高粮食利用效率的角度,我国生猪养殖宜继续推动大规模饲养。     

中国区域性耕地变化与粮食生产的关系研究——以东北地区为例

以东北地区为例,结合监测数据和农业统计数据,利用GIS技术分别开展耕地数量变化对粮播面积的影响分析、高中低产田内部各县粮食单产变化趋势分析、高中低产田内部耕地数量变化对粮食总产的影响以及粮食作物种植结构变化对粮食生产能力的影响评价与分析。结果表明:①东北地区耕地数量增加了188.8×10⁴hm²,总体呈北增南减趋势;②粮播面积增加了162.67×10⁴hm²,高产区的粮食单产多呈上升趋势,中产区的粮食单产稳中有升,低产区各县的粮食单产有增有减,但多数仍呈上升趋势;③高产田的粮食单产和低产田作物种植面积扩大促进了东北地区粮食总产的增加;④东北地区玉米生产进一步向吉林省集中,大豆、水稻、小麦向黑龙江集中,粮食生产的专业化、区域化趋势明显。