The effects of seston food quality on planktonic food web patterns

In planktonic food webs, the conversion rate of plant material to herbivore biomass is determined by a variety of factors such as seston biochemical/elemental composition, phytoplankton cell morphology, and colony architecture. Despite the overwhelming heterogeneity characterizing the plant–animal interface, plankton population models usually misrepresent the food quality constraints imposed on zooplankton growth. In this study, we reformulate the zooplankton grazing term to include seston food quality effects on zooplankton assimilation efficiency and examine its ramifications on system stability. Using different phytoplankton parameterizations with regards to growth strategies, light requirements, sinking rates, and food quality, we examined the dynamics induced in planktonic systems under varying zooplankton mortality/fish predation, light conditions, nutrient availability, and detritus food quality levels. In general, our analysis suggests that high food quality tends to stabilize the planktonic systems, whereas unforced oscillations (limit cycles) emerge with lower seston food quality. For a given phytoplankton specification and resource availability, the amplitude of the plankton oscillations is primarily modulated from zooplankton mortality and secondarily from the nutritional quality of the alternative food source (i.e., detritus). When the phytoplankton community is parameterized as a cyanobacterium-like species, conditions of high nutrient availability combined with high zooplankton mortality led to phytoplankton biomass accumulation, whereas a diatom-like parameterization resulted in relatively low phytoplankton to zooplankton biomass ratios highlighting the notion that high phytoplankton food quality allows the zooplankton community to sustain relatively high biomass and to suppress phytoplankton biomass to low levels. During nutrient and light enrichment conditions, both phytoplankton and detritus food quality determine the extent of the limit cycle region, whereas high algal food quality increases system resilience by shifting the oscillatory region towards lower light attenuation levels. Detritus food quality seems to regulate the amplitude of the dynamic oscillations following enrichment, when algal food quality is low. These results highlight the profitability of the alternative food sources for the grazer as an important predictor for the dynamic behavior of primary producer–grazer interactions in nature.     

氨基酸对烷烃降解菌GS3C降解性能的影响

从广州石油化工总厂污水处理站旁的油泥混合物中分离筛选得到一株烷烃降解菌GS3C,从生理生化及16S rDNA基因扩增测序等方面进行了鉴定,并在振荡好氧培养条件下研究该菌的降解性能及酵母浸膏、碳源、氮源、维生素、水解酪蛋白等营养物对其降解的影响,同时考察不同氨基酸对降解的影响. 结果表明,该菌的16S rDNA基因扩增序列与Burkholderia cepacia的同源性为97%,初步断定该菌株属于洋葱伯克霍尔德氏菌(Burkholderia cepacia),酵母浸膏能促进其对正十六烷的降解,其主要因素为氨基酸对降解的促进作用. 谷氨酸、脯氨酸、赖氨酸、缬氨酸及亮氨酸的混合物对降解菌GS3C的代谢促进作用最好,其中赖氨酸与脯氨酸为关键的2种氨基酸.      

高铁酸钾氧化去除弱碱性地下水中低浓度石油类污染物实验研究

研究一般地下水弱碱性水溶液中,高铁酸钾对低浓度石油烃类污染物的氧化去除率.采用0#柴油模拟石油类污染物试验水样,氧化反应在200mL烧杯中模拟完全混合状态完成.实验分析浓度分别为5.02mg/L、2.05mg/L、1.01mg/L和0.52mg/L4个水样石油类污染物氧化去除率.实验研究显示,石油类污染浓度与高铁酸钾浓...     

零价铁对污泥高温厌氧消化过程中四环素抗性基因及第一类整合子的消减影响

为研究污泥高温厌氧消化过程中零价铁(Fe0)对抗生素抗性基因的消减影响,采用荧光定量PCR方法定量检测了7种四环素抗性基因(TC-ARGs,包括tetA、tetC、tetG、tetM、tetO、tetW和tetX)及第一类整合子int I1基因在厌氧消化过程中的丰度变化,同时检测分析了挥发性脂肪酸(VFAs)的质量浓度变化,并探讨了目标基因与VFAs之间的相关关系.结果表明,适量Fe0(如0.10 g·g~(-1),以Fe0/VSS计)不仅可以强化污泥厌氧消化进程,显著提高总VFAs和乙酸的产生量,而且能够增强TCARGs和int I1基因的消减效果.尽管如此,过量Fe0(如1.17 g·g~(-1),以Fe0/VSS计)对污泥高温厌氧消化过程中TC-ARGs和int I1基因消减的增强效果并不显著,推测可能是由于基因水平转移的发生所导致的.通过相关性分析可知,TC-ARGs(除tetO基因外)和int I1基因与乙酸之间存在显著负相关性,表明乙酸可能对TC-ARGs和int I1基因的消减具有促进作用.     

利谷隆在土壤中的吸附过程与机理

利谷隆是一种广泛应用的除草剂。本文研究了它在４种不同理化特性土壤中的吸附过程（平衡吸附所需的时间,土壤ｐＨ的影响及吸附等温线）和在单离子饱和粘土矿物上的吸附机理,结果表明：利谷隆在土壤的吸附强度大（Ｋｔ值在３．８８－９３．８４）;达到吸附平衡的短（５ｈ）;ｐＨ值降低,有利于吸附,ｐＨ在４－６范围内变化较明显;另外,利谷隆在土壤中形成氢键、配位键及离子键是可能的。     

Production of a newly isolated Paenibacillus polymyxa biocontrol agent using monosodium glutamate wastewater and potato wastewater

A phyllosphere bacterial strain EBL-06 was isolated from wheat leaves. The morphology, cultural characteristics, phospholipid fatty acids, physiological and antagonistic fungus activities of this strain were investigated. A phylogenetic tree was constructed by comparing with the published 16S rDNA sequences of the relevant bacteria. The results showed that the isolate EBL-06 was a strain of Paenibacillus polymyxa; this strain performed a high level of antagonistic fungus activity toward a broad spectrum of phytopathogens, such as Botrytis cinerea, Cladosporium cucumerinum, Fusarium spp. The isolate EBL-06 can grow well using monosodium glutamate wastewater (MGW) and potato wastewater (PW) as culture medium. The maximum yield of 6.5 × 10 9 CFU/mL of the isolate EBL-06 anti-fungus biocontrol agent was reached in 15 hr cultivation at 28°C, pH 6.0–7.5 using the mixture of MGW and PW (1:9).     

黄山PM10中二元羧酸类化合物的季节变化特征及其来源

为研究黄山大气PM_(10)中二元羧酸类化合物的季节变化特征,分别于2015年夏季、冬季在黄山山顶采集PM_(10)样品,并分析二元羧酸、酮羧酸和α-二羰基化合物.结果表明,无论在夏季还是冬季,草酸(HOOC—COOH,C_2)均是浓度最高的二元羧酸,其次是丙二酸(HOOC—CH_2—COOH,C_3)、丁二酸[HOOC—(CH_2)_2—COOH,C_4],这与其它高海拔地区的分子组成是相似的.大部分二元羧酸的浓度呈冬低夏高的季节变化特征,但是冬季己二酸(C_6)和邻苯二甲酸(Ph)的浓度约高于夏季的2倍,表明冬季黄山大气受周边地区所排放的人为污染物的影响更大.作为二元羧酸的重要前体物,乙二醛(Gly)与甲基乙二醛(mGly)的浓度呈冬高夏低的季节变化特征,表明夏季黄山气溶胶的氧化性比冬季强.主成分分析(PCA)结果表明,黄山冬季SOA主要来自人为源的长距离传输,而夏季SOA主要是当地生物源经二次氧化形成.气溶胶无机模型(AIM)的计算结果表明,黄山夏季的C_2主要是经酸催化反应二次形成的.     

西安市大气中二元羧酸有机气溶胶组成及来源

为研究西安市冬季大气PM10中二元羧酸类有机气溶胶的组成和来源,采集了西安市2009年1~2月份的PM10样品,并利用GC/MS对样品中二元羧酸进行了化学表征.结果表明:西安市冬季大气中二元羧酸总浓度为(1597±725)ng/m3,其中草酸浓度最高[(1162±570)ng/m3],其次是邻苯二甲酸[(196±82)ng/m3]、丁二酸[(98±71)ng/m3]和丙二酸[(58±45)ng/m3].西安市二元羧酸浓度高于北京、南京、广州、香港等城市14%~350%,表明其污染严重,其中草酸相对含量远高于国内其他城市,显示西安市冬季大气气溶胶更为老化.C3/C4, C6/C9和Ph/C9比值及其相关性进一步表明二元羧酸主要来自光化学氧化.通过对水溶性有机碳(WSOC), 有机碳(OC), 元素碳(EC), 二次有机碳(SOC)的分析,发现WSOC主要来自于二次有机碳(SOC)的形成.另外,温度升高,相对湿度增加,导致春节后尽管燃煤排放污染物减少,但二元羧酸浓度并无降低,而相对含量较节前却显著增加.     

提高污泥碱性发酵挥发酸积累的新方法

为了加大剩余污泥在碱性条件下的水解酸化程度,本研究尝试了两种新的能促进污泥碱性发酵产酸的方式,分别是向批式的污泥碱性发酵系统中投加未灭菌发酵污泥和投加灭菌发酵污泥,结合温度的影响(10℃和35℃)分别考察了这两种方式对污泥水解酸化效果的影响.结果表明,中温有利于水解酶和产酸菌作用的发挥,增大了污泥的水解酸化程度,体系内有明显的挥发酸(VFAs)积累.35℃条件下,两种方式都在很大程度上促进了新鲜污泥的水解酸化程度,经灭菌后的发酵污泥的投加较等量的未灭菌的发酵污泥的投加效果更为显著.前者的水解速率是后者的2倍,发酵末期酸积累量为后者的1.5倍,且前者在较长的发酵时间内VFAs含量维持恒定.分析两种方式能促进污泥水解酸化的原因得到:未灭菌发酵污泥的投加是向系统中引入了一定量的产酸菌,灭菌发酵污泥的投加引入了大量的较易水解的有机底物.水解产物的增加能在更大程度上影响产酸的效果.因此,中温条件下向污泥碱性发酵系统中投加经灭菌处理后的发酵污泥是提高剩余污泥发酵产酸量更为有效的方式.     

臭氧-生物活性炭对微污染原水中典型持久性有机物的去除效果

以长三角地区J市典型有机微污染水源P水厂为研究对象,考察了臭氧-生物活性炭深度处理工艺对微污染水源水中有机物的去除效果.结果表明,臭氧-生物活性炭深度处理使高锰酸盐指数、总有机碳(TOC)和UV254的平均去除率分别提升19. 2%、10. 4%和23. 0%.水厂原水中检出8种多环芳烃(polycyclic aromatic hydrocarbon,PAHs)、16种有机氯农药(organochlorine pesticides,OCPs)、5种卤乙酸(haloacetic acids,HAAs),其总浓度分别为53. 9~100. 0、6. 5~41. 8、2. 5×103~1. 1×104ng·L~(-1),臭氧-生物活性炭深度处理对多环芳烃和有机氯农药的平均去除率分别为32. 5%和25. 9%,比常规处理工艺出水的水质有显著提升.卤乙酸的去除率为33. 8%~87. 0%,主要通过常规处理工艺去除;臭氧-生物活性炭深度处理对氯代乙酸略有去除,溴代乙酸有少量生成.