Conserving the abundance of nonthreatened species

Human modification of the environment is driving declines in population size and distributional extent of much of the world's biota. These declines extend to many of the most abundant and widespread species, for which proportionally small declines can result in the loss of vast numbers of individuals, biomass, and interactions. These losses could have major localized effects on ecological and cultural processes and services without elevating a species’ global extinction risk. Although most conservation effort is directed at species threatened with extinction in the very near term, the value of retaining abundance regardless of global extinction risk is justifiable based on many biodiversity or ecosystem service metrics, including cultural services, at scales from local to global. The challenges of identifying conservation priorities for widespread and abundant species include quantifying the effects of species’ abundance on services and understanding how these effects are realized as populations decline. Negative effects of population declines may be disconnected from the threat processes driving declines because of species movements and environment flows (e.g., hydrology). Conservation prioritization for these species shares greater similarity with invasive species risk assessments than extinction risk assessments because of the importance of local context and per capita effects of abundance on other species. Because conservation priorities usually focus on preventing the extinction of threatened species, the rationale and objectives for incorporating declines of nonthreatened species must be clearly articulated, going beyond extinction risk to encompass the range of likely harmful effects (e.g., secondary extinctions, loss of ecosystem services) if declines persist or are not reversed. Research should focus on characterizing the effects of local declines in species that are not threatened globally across a range of ecosystem services and quantifying the spatial distribution of these effects through the distribution of abundance. The case for conserving abundance in nonthreatened species can be made most powerfully when the costs of losing this abundance are better understood.     

用成组生物效应标记方法定量评价饮用水健康风险

饮用水安全性密切关系着民众的健康,因此相关的水质评价方法也日益受到关注.国家标准中规定的水质分析主要采用化学分析的方法,但该方法不能提供未知污染物的浓度及其所引起的健康影响,而生物效应标记测试则能弥补这一方面的不足.本研究应用一组生物效应标记方法评价自来水水质,包括利用SOS/umu测试评价遗传毒性,利用重组基因酵母测试评价类雌激素效应,利用鼠肝癌细胞(H4IIE)EROD诱导测试评价芳烃(Ah)受体效应或类二噁英物质总体水平,同时对这些生物毒性引起的健康风险进行了定量评价.用上述方法评价了北方某市9个水厂不同季节原水和出水水质.分析结果表明,该市主要自来水厂原水和出水中的直接和间接遗传毒性物质、类雌激素效应物质和芳烃受体效应物质浓度水平总体较低,风险在可接受水平;从处理效率来看,水厂现有工艺对类雌激素物质有很好的去除效果,而对于Ah受体效应类物质由于其总体浓度偏低而去除效果不很明显,少数水厂处理后由于消毒副产物的产生等原因,遗传毒性略有升高.曲此可见,应用生物效应标记方法能够对水厂的水源污染和水厂处理效果做出综合评价,该方法可以作为饮用水安全性评价的重要补充手段.     

Sorption of carbamazepine, 17α-ethinylestradiol, iopromide and trimethoprim to biomass involves interactions with exocellular polymeric substances

The sorption of carbamazepine (CBZ), iopromide (IOP), trimethoprim (TMP) and 17α-ethinylestradiol (EE2) was evaluated using four biomass types (pure ammonia oxidizing bacterial culture, two heterotrophic enrichment cultures with varying levels of oxygenase activity, and a full-scale nitrifying activated sludge (NAS) culture). CBZ and IOP did not sorb to the four biomass types. EE2 did not sorb to the pure culture but sorbed significantly to the heterotrophic cultures and NAS. TMP sorbed to the heterotrophic cultures and NAS, and was not evaluated for the pure culture. Three floc characteristics (hydrophobicity, median particle size, organic matter content) correlated moderately well with the EE2 organic matter sorption coefficient (K_OM,EE2). Zeta potential did not correlate well with K_OM,EE2 but did with K_OM,TMP, indicating that TMP sorption is more influenced by electrostatic factors than EE2. Once divalent cation-linked exocellular polymeric substances (EPS) were removed from flocs, EE2 and TMP sorption to the non-EPS (cellular) fraction decreased by approximately 50%. The correlation between K_OM,EE2 for the non-EPS cellular fraction deteriorated while the correlation between K_OM,TMP improved. EE2 seemed to sorb more strongly to EPS protein whereas TMP sorbed equally to polysaccharide and protein EPS. Attempts to develop predictive models were not successful. Pharmaceuticals that sorbed to biomass samples underwent biodegradation whereas those that did not sorb were not biodegraded, suggesting a relationship between sorption and pharmaceutical biotransformation.     

Structure-activity relationships of larvicidal monoterpenes and derivatives against Aedes aegypti Linn

In the search for larvicidal compounds against Aedes aegypti L. (Diptera: Culicidae), a collection of monoterpenes were selected and evaluated. R- and S-limonene exhibited the highest larvicidal potency (LC₅₀ = 27 and 30 ppm, respectively), followed by γ-terpinene (LC₅₀ = 56 ppm) and RS-carvone (LC₅₀ = 118 ppm). Structural characteristics which may contribute to the understanding of the larvicidal activity of monoterpenes were empirically identified. The presence of heteroatoms in the basic hydrocarbon structure decreases larvicidal potency. Conjugated and exo double bonds appear to increase larvicidal potency. Replacement of double bonds by more reactive epoxides decreases the larvicidal potency. The presence of hydroxyls in the cyclic structure resulted in decreased potency, probably due to increased polarity indicanting that lipophilicity seems to play an important role in increasing the larvicidal potency in this set of compounds.     

N1‐aryl‐N2‐dichloroacetyl glycine and alanineamides as selective safeners for corn against chloroacetanilide herbicides

Abstract

Structurally new N¹aryl‐N²‐dichloroacetyl glycine and alaninamides were prepared. Greenhouse experiments were conducted to determine the effectiveness of the new compounds in protecting corn seedlings from chloroacetanilide (acetochlor, alachlor, dimethachlor, metazachlor, metolachlor) injury using dichlormid and BASF‐145138 as standard safeners. High rates of chloroacetanilides caused significant injury to sensitive corn hybrids. The most acive derivatives reduced injury to corn from dimethachlor and metolachlor and lesser extent from acetochlor and metazachlor. The most effective derivatives of the new compounds displayed better safening activity than the standards. Some of the new compounds were found to be selective safeners when formulated as a tank mixture with metolachlor in a 1:33–100 safener‐to‐herbicide ratio showing the same or better activity than the standard used.

Nomenclature: BASF‐145138, 1‐dichloroacetyl‐hexahydro‐3,3,8α‐trimethyl‐pyrrolo‐[1,2‐α]—pyrimidin‐6‐(2H)‐one; EPTC, S‐ethyl‐N,N‐dipropylcarbamothioate; dichlormid, 2,2‐dichloro‐N,N‐di‐2‐propenyl acetamide; corn, Zea Mays L. ‘Pannonia SC’.     

城市化对河流着生硅藻物种和功能多样性的影响——以深圳市河流为例

着生藻类是河流生态系统的主要初级生产者,了解城市化对着生藻类多样性的影响对于城市河流管理具有重要意义.本研究以深圳市河流为例,研究了河流着生硅藻性状及物种、功能多样性对城市干扰的响应.研究发现城区和郊区的水质状况差异显著.城区样点的NH₄⁺-N、NO₂-N、TN、TP和DOC浓度是郊区的3～20倍不等.水环境的巨大变化也导致了河流着生藻类生物多样性的变化.城区组物种丰富度、Pielou指数和Simpson指数均显著高于郊区组,而功能均匀度则显著低于郊区组.并且在21个硅藻性状中,有15个性状在城区和郊区组间存在显著差异.进一步用随机森林模型拟合着生藻类生物多样性与水质指标的关系,结果发现硅藻性状对城市化反应较其他指标更为敏感.特别是小型、可动、低共位群和运动群这4个性状指标,构建的随机森林模型解释率能达到40%～60%,而生物多样性指数构建的模型解释率只有15%～25%左右.总体来说,TP和TN是影响城市河流着生硅藻多样性的主要水质指标.在营养水平高的城市样点.个体较大、能够移动的硅藻占有主导地位;而在营养水平较低的郊区...     

黑河流域产业结构与生态环境耦合关系辨识

产业结构作为人类作用于生态环境的主要环节．与区域资源、环境存在着显著的互动关系。在生态环境脆弱、水资源紧缺的西北干旱区内陆河流域,由于产业发展与流域生态环境及水资源的空间分布不相吻合．导致生态环境严重退化．目前亟需深入研究产业结构与生态环境的耦合关系。本文以黑河流域为典型研究区,通过建立生态环境质量及产业结构效益指标体系,对黑河流域上、中、下游的生态环境质量和产业结构效益作了综合评价,并对二者的耦合关系进行了定量辨识。结果表明：黑河流域产业结构效益自上游向下游在空间上呈倒“U”型,而生态环境质量与环境产业协调度沿河自上游向下游具有基本一致的变化趋势,都依次降低,说明现阶段黑河流域沿河自上游向下游,产业结构对生态环境的依赖性逐渐降低,而破坏性逐渐上升。     

用分子连接指数研究氯代芳香族化合物对绿藻的毒性及QSAR分析

本文测定了一批氯代芳香族化合物对羊角月牙藻的急性毒性,运用分子连接性指数分析了化合物结构与其毒性之间的定量关系,并用逐一抽取法检验比较了模型的稳健性.