Mesoscale variability of organic matter composition in nw adriatic sediments

We investigated the spatial variability of sediment organic matter content and composition in three areas (A, B and C) of the Northwestern Adriatic Sea, subjected to a putative gradient of trophic state ( i.e. , increasing distance from the Po river outflow) in order to determine the appropriate sample size and replication. The analysis of the mesoscale variability was carried out comparing variability on the scale of meters ( i.e. among different deployments) with the variability observed on a scale of several kilometres ( i.e. among different sampling areas). Sediment samples, collected on April 1999, October 1999, April and October 2000, were analysed for chloropigment content (chlorophyll-a and phaeopygments) and protein, carbohydrate and lipid concentrations. Chloropigment, protein, carbohydrate and lipid concentrations were high, indicating that this system shares trophic conditions typical of highly productive environments. All organic matter components displayed a distribution independent from the increasing distance from the Po river outflow and a clear spatial variability, characterised by significant differences among different areas, but not among deployments. Carbohydrates were the biochemical compound displaying the highest spatial variability among the three areas. Chloropigment, protein, carbohydrate and lipid concentrations displayed also significant temporal changes. When spatial and temporal variability were compared, chlorophyll-a, phaeopigment and protein concentrations displayed a higher temporal than spatial variability. Conversely, for carbohydrates and lipids spatial and temporal variability was of the same order of magnitude. Organic matter composition displayed limited changes among areas, but a strong temporal variability. The results from the Adriatic sea suggest that analyses from sediments collected from a single deployment are sufficient for assessing organic matter concentration and composition over areas of several hundreds of square meters. However, for estimating organic matter composition over larger spatial scales ( i.e. miles) the identification of different sampling areas is needed.     

Spatial distribution of organic geochemical record in the core sediments along the prominent zones of Central Kerala,India

The study investigated the origin, quality, composition, and trophic state of sedimentary organic matter (SOM) in core samples collected from three zones (Munambam, Vypin, Chettuva) of Central Kerala, India. The SOM exhibited enhanced levels for carbohydrate (CHO) followed by protein (PRT) and lipid (LPD); and phytopigment in the sediment followed the trend: Pheophytin (Pheo) > Carotenoid (carotend) > Chlorophyll-a (Chl-a) > Chlorophyll-b (Chl-b) > Chlorophyll-c (Chl-c). The low PRT: CHO ratio indicated a large amount of nonliving or aged organic matter in the sedimentary environment. Whereas the low Chl-a: Pheo ratio interprets the abundance of dead plant materials in the sediments. Correlation matrix showed strong association between organic matter and clay fraction of sediment. Furthermore, the strong interrelationships between biochemical components and chloropigments in all the zones suggested that SOM is strictly connected to phytodetritus deposition. Vypin zone near Vallarpadam Container Terminal revealed the presence of high biopolymeric carbon content. Besides, the PRT: CHO > 1 reflected the eutrophic condition at the same site but the low PRT: CHO ratio in the remaining stations displays the oligotrophic nature.     

Insights for Integrated Conservation from Attitudes of People toward Protected Areas Near Hwange National Park,Zimbabwe

Increase in human settlements at the edge of protected areas (PAs) is perceived as a major threat to conservation of biodiversity. Although it is crucial to integrate the interests of surrounding communities into PA management, key drivers of changes in local populations and the effects of conservation on local livelihoods and perceptions remain poorly understood. We assessed population changes from 1990 to 2010 in 9 villages located between 2 PAs with different management policies (access to natural resources or not). We conducted semi‐directive interviews at the household level (n =217) to document reasons for settlement in the area and villager's attitudes toward the PAs. We examined drivers of these attitudes relative to household typology, feelings about conservation, and concerns for the future with mixed linear models. Population increased by 61% from 2000 to 2010, a period of political and economic crisis in Zimbabwe. Forty‐seven percent of immigrants were attracted by the area; others had been resettled from other villages or were returning to family lands. Attitudes toward PAs were generally positive, but immigrants attracted by the area and who used resources within the PA with fewer restrictions expressed more negative attitudes toward PAs. Household location, losses due to wild animals, and restrictions on access to natural resources were the main drivers of this negative attitude. Profit‐seeking migrants did not expect these constraints and were particularly concerned with local overpopulation and access to natural resources. To avoid socio‐ecological traps near PAs (i.e., unforeseen reduced adaptive capacity) integrated conservation should address mismatches between management policy and local expectations. This requires accounting for endogenous processes, for example, local socio‐ecological dynamics and values that shape the coexistence between humans and wildlife. Percepciones para Conservación Integrada a Partir de las Actitudes de las Personas hacia Áreas Protegidas cerca del Parque Nacional Hwangem Zimbabwe     

“生物有效性测量”与“全沉积物毒性识别评估(TIE)”联用有效识别出沉积物中主要致毒污染物

沉积物中污染物种类繁多,准确判断其中产生生物毒性的主要来源是个难点,本文作者先采用TIE法初步判断出主要致毒污染物为有机物和重金属(毒性描述阶段(相I)),传统的毒性单位分析结果显示Cr、Cu、Ni、Pb和Zn主要致毒重金属,而为氯氰菊酯、氯氟氰菊酯、溴氰菊酯和氟虫腈为主要致毒有机物中(毒性鉴定阶段(相II))。采用4步分级提取法和Tenax提取法分析了重金属和有机物的生物有效性。生物有效性毒性单位分析更加准确地锁定了毒性主要贡献重金属为Zn、Ni和Pb,毒性主要贡献有机物为氯氰菊酯、氯氟氰菊酯和氟虫腈。沉积物的稀释降低了重金属的毒性并使其毒性贡献鉴定变得复杂,生物有效性测量可以有效地提高TIE结果的准确性。
精选自Xiaoyi Yi, Huizhen Li, Ping Ma and Jing You. Identifying the causes of sediment-associated toxicity in urban waterways in South China: Incorporating bioavailabillity-based measurements into whole-sediment toxicity identification evaluation. Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2970
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2970/full     

沉积物毒性鉴别评估技术在一个有着多重污染物输入地点的应用

沉积物毒性鉴别评估用于确定造成沉积物整体毒性测试中观察到有害效果的原因。然而在多污染物的情况下,将总体毒性划分为为不同个体污染物单独造成的毒性的方法存在很多问题。利用一个有着多重输入与相关污染物的站点数据,我们为毒性鉴别评估提出一种通过追踪毒性单位（TUs）来确定是否囊括全部毒性的方法。首先确定出沉积物整体的毒性水平,然后将毒性来源划分至几种污染物大类,例如氨类,金属,非极性有机物等。本文中毒性很大程度上来源于非极性有机物,所以在萃取沉积物之后,将萃取物重新加回稀释水中以检测毒性的复原。每一部分污染物的毒性占比由溶剂梯度测量,并进行毒性检测。目标占比由气相色谱-质谱分析得到,从而鉴定出与特定成分相关的毒性。之后对这些成分相关的毒性单位进行测定以确定可能的原因组合和是否已囊括全部毒性。数据表明毒性既与已有化合物相关,又与新兴污染物相关,而两种污染物对于总体毒性的具体贡献则随实验地点改变。
精选自Howard C. Bailey, Catherine A. Curran, Peter Arth, Bonnie P. Lo, Rich Gossett. Application of Sediment Toxicity Identification Evaluation Techniques to a Site with Multiple-Contaminants. Environmental Toxicology and Chemistry: Volume 35, Issue 10, pages 2456–2465, October 2016. DOI: 10.1002/etc.3488
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3488/full
     

Mineralization of particulate organic matter derived from coral-reef organisms in reef sediments of the Gulf of Aqaba

In situ and laboratory incubation experiments in a fringing reef in the Gulf of Aqaba were performed to study degradation rates of particulate organic matter in reef sediments. Coral mucus, clam eggs, and zooxanthellae were used as model particulate organic compounds for these experiments. Aerobic and anaerobic mineralization rates were calculated by dissolved inorganic carbon (DIC) and O₂ fluxes from the sediments under different particulate organic matter additions. Fast enhancement (approximately twofold) of O₂ and DIC fluxes were found with the addition of coral mucus and clam eggs compared with control incubations without addition. Most of the degradation is believed to have occurred anaerobically rather than aerobically (DIC:O₂ ratios were 4.3–28.1). Higher degradation rates of coral mucus and clam eggs were estimated in carbonate sediment than in silicate sediment (1.2–1.6-fold), which was attributed to the different physical and chemical properties of both sediments. Our study shows the significance of the reef sediment as a suitable site for microbial degradation of particulate organic material excreted from different reef community organisms. This may increase the regeneration of nutrients in the reef environment necessary to sustain high biological productivity.     

Determination of persistent organic pollutants in sediment and fish of the western coast of Alexandria,Egypt

Persistent organic pollutants (POPs) were recorded in sediment and fish samples collected from the western coast of Alexandria. Total hydrocarbons (aliphatic+PAHs ) in sediment ranged from 683.8 to 34670.1 ng g ^?1 with an average of 9286.9 ng g ^?1. The sum of C16–C34 of aliphatic fractions was<4000?ng g;^?1, indicating the presence of a fresh petroleum source. For all sediments, the anthracene/phenanthrene ratio was>0.1, suggesting the dominance of a pyrolytic source. Total aliphatics in different fish species ranged from 253 to 11?132 ng g;^?1, while total PAHs ranged from 3862 to 35?746 ng g;^?1 wet weight. Benzo[a]pyrene was the most dominant PAH fraction ranged from 1902.7 to 32 905.5 with an average of 9464.5?ng g;^?1 wet weight in all fish species. Concentrations of polychlorinated biphenyls (PCBs) ranged from 0.79 to 64.9?ng g;^?1 with an average 12.14?ng g;^?1 wet weight. The concentrations of organochlorines in fish species (Euthynnus alleferatus, Scomberomorus commerson, Sphyraena Sphyraena, Diplodus vulgaris, and Alepes djedaba) decreased following the order: PCBs>DDTs>HCHs>total cyclodienes. Concentrations of DDTs in fish tissues ranged from 4.89 to 36.37 ng g^?1 with an average of 16.4?ng g;^?1 wet weight. The concentrations of total HCHs ranged from 0.3 to 65.7?ng g;^?1 with an average of 16.35?ng g;^?1. The present study indicates: (1) fresh petroleum input where Pr/Ph>1; (2) PAHs in sediment<4000 ng g ^?1; (3) BaP concentration exceeded the permissible levels in Alepes djedaba species; (4) DDTs in sediment were below the effective range low level; (5) PCBs>effective range low and相似文献   

A Geochemical and Biological Basis for Marine Sediment Quality Guidelines

This document describes a basis for the establishment of marine sediment quality guidelines for regulatory applications. It outlines a geochemical basis for identifying potential anomalies in the presence of inorganic contaminants in marine sediments and a biological or ecotoxicological basis for determining concentrations unlikely to result in adverse biological effects. These approaches are discussed in an exploratory fashion. It is intended that both approaches could be combined in a manner that takes account of sedimentary nature and composition as a conceptual and practical approach to the establishment of guidelines for regulatory applications associated with the protection of the marine environment.     

Behaviour of trace metals in surface sediments of the Black Sea

Early diagenetic processes control the behavior, and more specifically the dissolved‐solid phase distribution of heavy metals in sediments. The depth distribution of Co, Mn, Cu, Zn, Ni, and Fe in sediment were determined in box cores from the Black Sea. The sequential analyses results of these metals indicate contrasting behavior of Mn and Co during early diagenesis, consistent with their respective chemistries and particle‐associations. The profiles of extractable trace metals in the cores are clearly related to sediment type or depositional environment. Topmost sections of the profiles for these elements are generally similar, i.e. rapid decrease in concentration below the sediment surface.     

A generalized approach for producing,quantifying, and validating citizen science data from wildlife images

Citizen science has the potential to expand the scope and scale of research in ecology and conservation, but many professional researchers remain skeptical of data produced by nonexperts. We devised an approach for producing accurate, reliable data from untrained, nonexpert volunteers. On the citizen science website www.snapshotserengeti.org , more than 28,000 volunteers classified 1.51 million images taken in a large‐scale camera‐trap survey in Serengeti National Park, Tanzania. Each image was circulated to, on average, 27 volunteers, and their classifications were aggregated using a simple plurality algorithm. We validated the aggregated answers against a data set of 3829 images verified by experts and calculated 3 certainty metrics—level of agreement among classifications (evenness), fraction of classifications supporting the aggregated answer (fraction support), and fraction of classifiers who reported “nothing here” for an image that was ultimately classified as containing an animal (fraction blank)—to measure confidence that an aggregated answer was correct. Overall, aggregated volunteer answers agreed with the expert‐verified data on 98% of images, but accuracy differed by species commonness such that rare species had higher rates of false positives and false negatives. Easily calculated analysis of variance and post‐hoc Tukey tests indicated that the certainty metrics were significant indicators of whether each image was correctly classified or classifiable. Thus, the certainty metrics can be used to identify images for expert review. Bootstrapping analyses further indicated that 90% of images were correctly classified with just 5 volunteers per image. Species classifications based on the plurality vote of multiple citizen scientists can provide a reliable foundation for large‐scale monitoring of African wildlife.