城市污水厂初沉池的设置方式及运行效果

跟据初沉池在城市污水厂长期的实际运行数据,分析了初沉池去除污水中的悬浮物、有机物、降低能耗、降低水质波动对生化系统的冲击等方面所起的作用,设置初沉池还有利于提高生化系统污泥的活性成份（MLVSS／MLSS）、增强出水效果;同时探讨了初沉池在城市污水处理中的设置方式,通过设置超越管线,在冬、夏季水质波动较大,保持生化系统进水有机负荷的稳定,提出了优化初沉池的处理效果的运行方式。     

Identification of Forest Vegetation Using Vegetation Indices

Abstract

Spectral feature of forest vegetation with remote sensing techniques is the research topic all over the world, because forest plays an important role in human beings' living environment. Research on vegetation classification with vegetation index is still very little recently. This paper proposes a method of identifying forest types based on vegetation indices, because the contrast of absorbing red waveband with reflecting near-infrared waveband strongly for different vegetation types is recognized as the theoretic basis of vegetation analysis with remote sensing. Vegetation index is highly related to leaf area index, absorbed photosynthetically active radiation and vegetation cover. Vegetation index reflects photosynthesis intensity of plants and manifests different forest types. According to reflectance data of forest canopy and soil line equation NIR=1.506R+0.0076 in Jingyuetan, Changchun of China, many vegetation indices are calculated and analyzed. The result shows that the relationships between vegetation indices and forest types are that perpendicular vegetation index (PVI) identifies broadleaf forest and coniferous forest the most easily; the next is transformed soil-adjusted vegetation index (TSVI) and modified soil-adjusted vegetation index (MSVI), but their calculation is complex. Ratio vegetation index (RVI) values of different coniferous forest vary obviously, so RVI can classify conifers. Therefore, the combination of PVI and RVI is evaluated to classify different vegetation types.     

保护性耕作对玉米田土壤中除草剂残留的影响

保护性耕作能够显著提高土壤有机质,改善土壤质量,但是关于保护性耕作如何影响农药等污染物在土壤中残留的研究却较为匮乏,而土壤污染又与粮食安全息息相关.因此,选择7个实验地点,针对传统耕作与保护性耕作两种耕作方式下土壤中3种除草剂(乙草胺、阿特拉津和二甲四氯钠)残留特征进行了分析.结果表明,保护性耕作显著影响土壤的总有机碳含量、土壤含水率和土壤团聚体平均粒径等性质[使(2.1±0.1)%、(19.1±1.2)%和(82.2±3.0)μm分别增加至(2.9±0.3)%、(22.3±1.5)%和(97.2±4.2)μm].研究进一步发现,保护性耕作对不同除草剂在土壤中残留的影响存在差异性.例如,保护性耕作通过影响土壤总有机碳含量显著增加东丰试验田土壤中阿特拉津的含量[使(3.8±0.3)ng·g^-1增加至(17.7±3.0)ng·g^-1],通过影响土壤团聚体平均粒径显著降低德惠试验田土壤中乙草胺的含量[使(50.6±10.3)ng·g^-1降低至(9.2±2.5)ng·g^-1].然而,由于不同土壤性质对土壤中...     

环境因素对供应链中生产者食品安全行为的影响机制仿真分析

通过食品安全环境因素的改善和规范,来提高食品安全效果是具有现实意义的。本文归纳了影响食品安全的环境因素,特别是影响生产者食品安全行为的环境因素;环境因素对供应链食品安全的影响主要体现在生产者食品安全行为的选择上,为此,设计了环境因素对供应链生产者食品安全行为影响机制;为了分析环境因素对供应链中生产者食品安全的影响,从生产者食品安全行为的影响机制中选取了消费者食品安全意愿、生产者市场占有率、罚款金额等环境因素,以生鲜蔬果供应链中覆盖流通领域的那个部分提出了生产者食品安全行为选择策略的仿真模型,使用Netlogo软件进行了多主体仿真。通过仿真发现,食品监管的手法还宜细化,提升技术因素可以有效改善中国的食品安全水平。     

火电厂脱硝技术现状及产业与市场发展预测

概述了我国火电厂脱硝的背景及国家发布的有关技术政策和相关标准,介绍了国内火电脱硝技术及脱硝产业的发展现状,对火电脱硝市场的发展进行了预测。     

A critical exploration of blood and environmental chromium concentration among oral cancer patients in an oral cancer prevalent area of Taiwan

The growing incidence of oral cancer (OC) in Taiwan has become a crucial public health concern. In particular, Changhua, a county in central Taiwan, carries persistently high OC incidence rate, with an alarmingly high male/female ratio of OC incidence. Previous epidemiological studies had found that the incidence is spatially correlated with the level of soil content to certain heavy metals in the central Taiwan area. Soil and the human body both intake environmental heavy metals, which can be absorbed through various ways. The soil metal concentration is an index of possible environmental exposure to heavy metal, and the blood metal concentration somewhat reflects the level of the exposure on the human body. Metallic carcinogen is likely to generate free radicals and play a role in many cancers, and many studies had reported that environmental exposure to heavy metals is an important risk factor for developing cancer. Studies on animals showed that chronic intake of chromium (Cr) could induce OC. This study aims to explore the association between the Cr concentration in the farm soil and in the blood of OC patients. We recruited 79 OC patients from Changhua County, with their lifestyle being adjusted in regression analysis. The results showed that the Cr concentration in the blood of OC patients is significantly higher than the background value, and is positively associated with the Cr concentration in the soil surrounding their residence (p-value < 0.023). Because Changhua County is only with moderate prevalence of the known OC habitual risk factors, an environmental factor related to heavy metal Cr exposure is suspected. Future investigations may verify the causal relation between Cr and OC.     

劳动防护用品与职工福利异同点及意义浅析

1引言如今,人们对劳动防护用品及其作用的认识日渐深刻,它已不再是可有可无,更不是企业或单位的点缀品,而是实实在在地成为实现安全生产不可或缺的重     

Enantioselective ecotoxicity of the herbicide dichlorprop and complexes formed with chitosan in two fresh water green algae

To reduce the leaching potential, to prevent groundwater contamination and to maintain the efficacy of a pesticide, natural polysaccharides have received increasing attention due to their biocompatibility and useful biological reactivity for controlled release formulations (CRFs) of pesticides. In this paper, the toxicities of the chiral herbicide dichlorprop (DCPP) and its complexes with chitosan molecules (DCPP-CS) and chitosan nanoparticles (DCPP-NP) to two different green algae were determined and compared. The inhibition rates of DCPP, DCPP-CS and DCPP-NP were determined at 24, 48, 72, 96, 120, 144, 168 h, and the results show that (S)-DCPP was more toxic to Chlorella vulgaris than (R)-DCPP, while the (R)-DCPP was more toxic to Scenedesmus obliquus than (S)-DCPP. The study also found that the chiral selectivity of DCPP to Chlorella vulgaris and Scenedesmus obliquus could be changed when DCPP was complexed with chitosan molecules (CS) or chitosan nanoparticles (NP). For Chlorella vulgaris, the order of inhibition was (R)-DCPP-CS > (S)-DCPP-CS and (R)-DCPP-NP > (S)-DCPP-NP; for Scenedesmus obliquus, the order was (S)-DCPP-CS > (R)-DCPP-CS and (S)-DCPP-NP > (R)-DCPP-NP. This phenomenon suggests that the enantioselective behaviors of chiral compounds might shift when interactions with other chiral receptors coexist in different biological environments. Additionally, chitosan molecules and chitosan nanoparticles also showed different toxicities, which could be ascribed to the difference in the physicochemical properties between CS and NP or the differences in the cell walls of the two fresh water green algae.     

不同水体沉积物中磷的形态分析

磷是生态系统中必不可少的营养元素,其含量与水体的营养程度密切相关,过剩的磷会导致水体富营养化,使生态平衡遭到破坏.就不同水体沉积物中磷的形态进行了分类综述,归纳总结了不同水体沉积物中磷的形态以及分布特征,并且进一步概述了影响沉积物中磷向水体释放的因素.     

药渣生物炭基质联合麦饭石对土壤-黑麦草体系的调控与机制

以板蓝根药渣为原料,选择300℃和500℃厌氧裂解制备2种生物炭(BC300和BC500)、BC500载Fe改性炭(FeBC500)、天然麦饭石(MFS)、BC500与MFS等质量组合[BC500∶MFS(1∶1)]、Fe-BC500与MFS等质量组合[Fe-BC500∶MFS(1∶1)]材料为钝化剂,采用室内盆栽实验和等温吸附实验,研究了其对土壤-黑麦草体系的调控效果,并通过比表面孔分布测定(BET)、扫描电镜分析(SEM)、X射线衍射(XRD)和傅里叶变换红外光谱(FTIR)探讨了其机制.结果表明,在添加量为2%(土)时,BC300、BC500、Fe-BC500、MFS、BC500∶MFS(1∶1)和Fe-BC500∶MFS(1∶1)均可显著降低(P 0. 05)黑麦草体内Cu和Cd含量以及显著增加黑麦草的生物量,且黑麦草的叶绿素含量和根系活力均可指示这一效果. BC300处理抑制黑麦草吸收Cu和Cd,增加黑麦草的生物量的效果要优于其他处理,可使黑麦草地下部分Cu和Cd含量分别减少44. 78%和63. 89%,地上部分分别减少76. 34%和53. 40%;地下部分生物量增加327. 22%,地上部分生物量增加504. 11%. Langmuir方程更好地拟合BC300、BC500和Fe-BC500的吸附效果,且对Cu的最大吸附量分别为8. 02、9. 20和8. 82 mg·g~(-1);对Cd的最大吸附量分别为7. 97、8. 51和7. 70 mg·g~(-1). Freundlich方程能更好地拟合MFS的吸附效果,对Cu和Cd的最大吸附量分别为7. 03 mg·g~(-1)和6. 10 mg·g~(-1). BC300和BC500主要通过其表面羟基、羧基、羰基和酯基,Fe-BC500主要通过其表面羟基和铁羟基,MFS主要通过其中Na Al Si3O8和Al2Si2O5(OH)4表面的硅羟基、羟基和羧基分别与Cu和Cd发生配合反应,进而达到钝化修复Cu和Cd污染土壤的效果.因此,药渣生物炭、铁改性药渣生物炭和麦饭石及其组合材料均可被用于Cu和Cd复合污染土壤修复,但修复机制不同.