Practitioner Insights into Weed Management on California’s Rangelands and Natural Areas

Working rangelands and natural areas span diverse ecosystems and face both ecological and economic threats from weed invasion. Restoration practitioners and land managers hold a voluminous cache of place-based weed management experience and knowledge that has largely been untapped by the research community. We surveyed 260 California rangeland managers and restoration practitioners to investigate invasive and weedy species of concern, land management goals, perceived effectiveness of existing practices (i.e., prescribed fire, grazing, herbicide use, and seeding), and barriers to practice implementation. Respondents identified 196 problematic plants, with yellow starthistle (Centaurea solstitialis L.) and medusahead (Elymus caput-medusae L.) most commonly listed. Reported adoption and effectiveness of weed management practices varied regionally, but the most highly rated practice in general was herbicide use; however, respondents identified considerable challenges including nontarget effects, cost, and public perception. Livestock forage production was the most commonly reported management goals (64% of respondents), and 25% of respondents were interested in additional information on using grazing to manage invasive and weedy species; however, 19% of respondents who had used grazing for weed management did not perceive it to be an effective tool. Across management practices, we also found common barriers to implementation, including operational barriers (e.g., permitting, water availability), potential adverse impacts, actual effectiveness, and public perception. Land manager and practitioner identified commonalities of primary weeds, management goals, perceived practice effectiveness, and implementation barriers across diverse bioregions highlight major needs that could be immediately addressed through management–science partnerships across the state’s expansive rangelands and natural areas.     

我国区域空气污染治理效率及其影响机制——基于超效率SBM模型和门槛回归模型

随着人民对美好生活需求的日益增长,政府空气污染治理的效率问题日益得到重视。本文从地方政府空气污染治理效率及其影响因素的视角入手,以全国30个省份为研究对象,运用超效率SBM模型测算2003—2015年各省级区域的空气污染治理效率。在此基础上,运用门槛回归模型分析政府空气污染治理效率的影响机制。研究表明:①地区间空气污染治理效率差异性较为显著。中部、西部空气污染治理效率整体呈下降趋势。东部和东北地区空气污染治理效率则上升比较平稳。②政策规划、碳源、污染物排放和环境治理投入表现出双重门槛特征,其中碳源对空气污染治理效率影响显著,而以碳为首的能源消费结构则主要对中部和西部空气污染治理效率产生影响。落后地区政府应注重产业升级,财政上应对碳税等税目进行征收,产业上应鼓励企业创新,并对落后企业进行倒逼升级。     

Estimating sampling frequency in pollen exposure assessment over time

A time series model was fitted to the pollen concentration data collected in the Greater Cincinnati area for the Cincinnati Childhood Allergy and Air Pollution Study (CCAAPS). A traditional time series analysis and temporal variogram approach were applied to the regularly spaced databases (collected in 2003) and irregularly spaced ones (collected in 2002), respectively. The aim was to evaluate the effect of the sampling frequency on the sampling precision in terms of inverse of standard error of the overall level of mean value across time. The presence of high autocorrelation in the data was confirmed and indicated some degree of temporal redundancy in the pollen concentration data. Therefore, it was suggested that sampling frequency could be reduced from once a day to once every several days without a major loss of sampling precision of the overall mean over time. Considering the trade-offs between sampling frequency and the possibility of sampling bias increasing with larger sampling interval, we recommend that the sampling interval should take values from 3 to 5 days for the pollen monitoring program, if the goal is to track the long-term average.     

Oxidative degradation of phenol by sulfidated zero valent iron under aerobic conditions: The effect of oxalate and tripolyphosphate ligands

After adding either organic or inorganic ligands, sulfidated nano-zero-valent iron (SnZVI) was used for aerobic degradation of phenol, and the effect of the ligand species on oxidation performance was investigated. We found that SnZVI hardly degraded phenol in the absence of ligand addition. Ligands initiated and promoted the degradation of pollutants by SnZVI. The data herein show that a characteristic inorganic ligand, tripolyphosphate (TPP), is more effective in enhancing oxidation than a characteristic organic ligand oxalate. In addition to the scavenging of reactive oxidants by the organic ligand, more ferrous ion (Fe(II)) dissolution from SnZVI in the TPP system is another cause for the superior enhancement by the inorganic ligand. In the oxalate system, as the sulfur content of SnZVI increased, the oxidation efficiency increased because FeS shell promoted the transfer of electrons to produce more reactive oxygen species (ROS). In TPP system, the effect of sulfur content on oxidation performance is more complex. The SnZVI with low sulfur content showed poor oxidation performance compared with that of nZVI. Further experiments proved that sulfidation might weaken the complexation of TPP with surface bound Fe, which would slow down the ionic Fe(II) dissolution rate. Therefore, sulfidation has the dual effects of enhancing electron transfer and inhibiting the complexation of inorganic ligands. In addition, the mechanisms of ROS generation in different ligand systems were investigated herein. Results showed that the critical ROS in both the oxalate and TPP systems are hydroxyl radicals, and that they are produced via one-electron activation of O₂.     

Applying Integrated Urban Water Management Concepts: A Review of Australian Experience

This article explores recent Australian experiences in the application of the concept of integrated urban water management (IUWM) to land development sites through the review of 15 case studies. It discusses lUWM’s emergence and comments on the success or otherwise of Australian experience in its application. The understanding of IUWM is maturing within the Australian water industry, an occurrence that has been facilitated by demonstration sites such as those reviewed. Successes include the translation of IUWM concepts into well-functioning operational urban developments, significant reductions in the impact of the urban developments on the total water cycle, and the increasing acceptance of the concept within the water and land development industries. However, there is still room for greater integration of the water supply, stormwater, and wastewater components of the urban water cycle, improved dissemination of knowledge, enhancement of skills in both public and private organisations, and monitoring the performance of systems and technologies.     

中国各省区工业用水效率影响因素的空间分异

工业用水效率是影响工业用水的直接因素,剖析其影响因素并找出空间分布规律是提高中国工业用水效率的关键。通过选取Super-SBM模型,引入非期望产出指标来测算中国31省2007～2016年的工业用水效率,并从多方面综合分析工业用水效率影响因素的空间动态演变状况,以求研究结果为制定有差异的区域集约型水资源管理政策提供依据。结果发现:(1)我国多数省份的工业用水处于无效率状态,同时高效率中心由东向西转移;(2)不同影响因素对工业用水效率的影响关系不同。水资源总量、地区生产总值、工业用水占比、RD投入占比的增多对工业用水效率有负向影响,工业用水效率会降低;而地区常住人口、城镇化率和人均教育支出的增多对工业用水效率有正向影响,促进工业用水效率提升。(3)不同影响因素对中国工业用水效率的影响程度存在空间差异。城镇化率、RD投入占比和人均教育支出对工业用水效率带来的影响作用在空间上相对集中,影响高值区主要落在中部和西部地区,低值区主要在东部沿海;而水资源总量、地区生产总值、工业用水占比和地区常住人口的影响在空间上呈现一种演变的状态,随时间发展影响高值区和低值区都发生了中心转移。     

好氧颗粒污泥膜生物反应器污泥性状研究

采用厌氧-好氧运行方式的颗粒污泥膜生物反应器（GMBR）,连续运行近120　d表现出良好的有机物去除及同步硝化反硝化能力.对GMBR中污泥粒径分布变化研究表明,GMBR中污泥浓度的增加主要是由于粒径0.18～0.45　mm的小颗粒污泥及小于0.18　mm的絮状污泥的增加造成的,粒径大于0.45　mm的颗粒污泥能够基本稳定维持其颗粒形态,反应器运行末期,GMBR中颗粒污泥（粒径大于0.18　mm的污泥）含量稳定在污泥总量的60％～65％以上.污泥表面电荷量随着污泥组成形态的变化电负性逐渐增加,80　d后稳定在-0.42～-0.80　meq·g^-1之间.污泥表面电荷的负电性增加主要是由小于0.45　mm的污泥造成的,其中小于0.18　mm的絮状污泥对其影响最大.并且,污泥粒径越大污泥表面负电荷量越少,两者具有较好的线性关系.另外,GMBR中SVI稳定在60～90 mL/g之间,并且随着污泥表面电荷负电性的增加污泥SVI值增加,两者之间具有一定的相关性.     

颗粒污泥SBR处理生活污水同步除磷脱氮的研究

采用厌氧-好氧的SBR运行方式,以人工配水培养的好氧颗粒污泥为接种污泥,处理碳、氮、SS浓度均较高的生活污水,研究了系统中颗粒污泥的稳定性及其去除有机物和同步除磷脱氮的效果.经过1个月的驯化培养,颗粒污泥即可呈现出良好的污染物去除性能并趋于稳定,反应器中颗粒污泥含量始终占污泥总量的68%以上.颗粒污泥系统污泥浓度为5 000～6000mg/L,SVI值为20～35 mL/g.经过3个月的运行后,反应器中颗粒污泥由原来以粒径0.6～0.9 mm的中等大小颗粒占主体变为粒径＞1.25 mm的大颗粒占主体.稳定运行阶段颗粒污泥系统对COD、TOC、磷酸盐、氨氮、总氮和SS的平均去除率分别为83.04%、70.41%、94.30%、86.51%、41.82%和85.89%.对反应器运行过程中典型周期的分析,反映出颗粒污泥良好的同步除磷脱氮效果.     

硫酸铵气溶胶对甲苯-NOx-空气体系光化学反应的影响

利用大气模拟烟雾箱,研究了硫酸铵气溶胶对甲苯-NOx-空气体系光化学反应的影响.结果表明,硫酸铵作为气溶胶种子,其存在可以加快反应过程中颗粒物(particle matter,PM)的生成速度,并提高甲苯的气溶胶产率.在高浓度的硫酸铵气溶胶种子条件下,其初始浓度对反应过程中NOx、NO和O3的浓度变化没有明显的影响,但对二次有机气溶胶(secondary organic aemsol,SOA)的生成有显著影响.在硫酸铵气溶胶种子浓度小于160 μg·m-3时,SOA的产率随初始气溶胶种子浓度的增大而增大,从最小7.2%到最大11.7%,其增幅超过60%.