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Resultados 1861-1870 de 4,937
Distribution and pollution assessment of heavy metals in the intertidal zone environments of typical sea areas in China Texto completo
2019
Zhao, Mengwei | Wang, Enkang | Xia, Peng | Feng, Aiping | Ji, Yuan | Sun, Yonggen
The heavy metals (Cu, Cr, Zn, Cd, Pb) were analysed for 217 surface sediment samples collected across 14 typical intertidal zone areas in China. The data reveals the heavy metals spatial distribution patterns and correlations among their concentrations. Cu, Zn, Cd and Cr showed similar trends of spatial variation and the correlations between the concentrations of every two heavy metals were significantly positive except for the correlation between Pb and Cr concentrations. By using Nemerow index method, Enrichment factor and Sediment Quality Guidelines, it is found that Hangzhou Bay and Jiulong River Estuary were polluted, Yingluo Bay and Dongzhaigang Bay were Cd-rich areas. Except Beidaihe shoal, Sishili Bay and Yingluo Bay that were not exposed to any ecological risk of heavy metals and had no adverse biotoxic effects, the other 11 typical intertidal zone areas were exposed to moderate ecological risk of heavy metals in the sediment with potential adverse biotoxic effects.
Mostrar más [+] Menos [-]Risk assessment and source apportionment of PAHs in surface sediments from Caofeidian Long Island, China Texto completo
2019
Han, Bin | Zheng, Li | Lin, Faxiang
Sediment samples were collected from Caofeidian Long Island, China to investigate the contamination level and distribution pattern of 16 polycyclic aromatic hydrocarbons (PAHs). Source identification and risk assessment were also performed on these PAHs. The distribution patterns and source identification results indicated that the PAHs in the survey area originated from coal, biomass, and petroleum combustion as well as the combination of these three processes. Although the concentration of fluorene in the sediment exceeded the ERL level in some sampling sites, the effect range low–effect range median ratio implied a relatively low level of toxicity in these sediments. Meanwhile, the mean effects range–median quotient indicated that the 16 PAHs in sediments from Caofeidian Long Island pose a low ecological risk.
Mostrar más [+] Menos [-]Do beachrocks affect microplastic deposition on the strandline of sandy beaches? Texto completo
2019
Pinheiro, Lara M. | Monteiro, Raqueline C.P. | Ivar do Sul, Juliana A. | Costa, Monica F.
The strandline is one of the first deposition habitats of microplastics before they are integrated to the beach as a standing stock or finally removed. Beaches, entirely or partially protected by beachrocks, have different sediment dynamics and therefore may present variation in microplastic deposition. The aim of this work was to test if protected and unprotected (i.e., exposed to waves) areas of a sandy beach present different microplastic accumulation on the strandline – a habitat greatly influenced by both water and sediment dynamics. Microplastic (MP) amounts were significantly higher at the protected area (Mprotected = 642.6 ± 514.8 MP m−2, Mexposed = 130.6 ± 126.8 MP m−2, Mann-Whitney U test, U = 14.5, p = 0.0009), showing that beachrocks influence microplastic accumulation on the beach face. Therefore, hard structures parallel to the beach may also affect microplastics deposition on beach sediments, being important to consider these structures on microplastic surveys.
Mostrar más [+] Menos [-]Decision analysis to support wastewater management in coral reef priority area Texto completo
2019
Barnes, Megan D. | Goodell, Whitney | Whittier, Robert | Falinski, Kim A. | Callender, Tova | Htun, Hla | LeViol, Cecilia | Slay, Hudson | Oleson, Kirsten L.L.
A cocktail of land-based sources of pollution threatens coral reef ecosystems, and addressing these has become a key management and policy challenge in the State of Hawaiʻi, other US territories, and globally. In West Maui, Hawaiʻi, nearly one quarter of all living corals were lost between 1995 and 2008. Onsite disposal systems (OSDS) for sewage leak contaminants into drinking water sources and nearshore waters. In recognition of this risk, the Hawaiʻi State Department of Health (DOH) is prioritizing areas for cesspool upgrades. Independently, we applied a decision analysis process to identify priority areas to address sewage pollution from OSDS in West Maui, with the objective of reducing nearshore coral reef exposure to pollution. The decision science approach is relevant to a broader context of coastal areas both statewide and worldwide which are struggling with identifying pollution mitigation actions on limited budgets.
Mostrar más [+] Menos [-]Well-intentioned, but poorly implemented: Debris from coastal bamboo fences triggered mangrove decline in Thailand Texto completo
2019
Pranchai, Aor | Jenke, Michael | Berger, Uta
Along the Upper Gulf of Thailand, coastal fences and breakwaters have been constructed using bamboo since 2005. Despite their potential benefits, bamboo structures disintegrate within seven years releasing floating debris which severely damages mangrove tree stems. The aim of the study was to investigate whether such stem damage resulted in the decline of Avicennia spp. stands along the Upper Gulf of Thailand. Tree health assessments were conducted to assess the probability of crown dieback in damaged and undamaged trees. Satellite-derived time-series of vegetation indices were used to detect long-term forest decline. In contrast to the unaffected landward mangroves, seaward mangroves were unable to recover from insect-induced defoliation events after the collapse of a nearby fence. Furthermore, there was a significantly higher probability that damaged trees showed signs of moderate-to-severe crown dieback. It is recommended that bamboo fences be secured by replacing individual stems before they become detached.
Mostrar más [+] Menos [-]Effects of Surface Active Additives on the Enzymatic Treatment of Phenol and Its Derivatives: a Mini Review Texto completo
2019
Alshabib, Muntathir | Onaizi, Sagheer A.
PURPOSE OF REVIEW: Phenolic wastewaters represent a serious health and environmental problem. The remediation of phenolic wastewaters using oxidoreductase enzymes has emerged as an attractive environmentally friendly treatment method. However, the loss of enzyme activity during the treatment remains a key limitation. Thus, the aim of this article is to review and assess the recent progress in utilizing surface active additives (i.e., polymers, biopolymers, surfactants, and biosurfactants) for the reduction of enzyme inhibition and, thus, the enhancement of enzymatic remediation of phenolic wastewaters. RECENT FINDINGS: The reported effect of polymeric and surfactant additives on the enzymatic remediation of phenolic pollutants is mixed. Some studies reported significant enhancements while others demonstrated minimal or no gains. More seriously, it has been reported that these fossil-based additives might lead to a higher toxicity of the treated wastewaters. Bio-based (biopolymers and biosurfactants) additives might address this toxicity issue; however, the bio-based additives are not always as effective as the fossil-based ones. Despite the beneficial effect, with some exceptions, of additives, the enhancement level varies widely, probably due to the variations in the reaction environment. Thus, to draw meaningful and reliable conclusions on which additive(s) is more promising, thorough studies under unified conditions are needed. Additionally, generation of secondary pollutions associated with the fossil-based additives urges the replacement of such additives with bio-based ones. However, the effectiveness of the bio-based additives is still not sufficiently documented, stressing the need for more in-depth studies.
Mostrar más [+] Menos [-]Tracing the source of Pb using stable Pb isotope ratios in sediments of eastern Beibu Gulf, South China Sea Texto completo
2019
Xu, Dong | Wang, Rong | Wang, Weiguo | Ge, Qian | Zhang, Wenli | Ma, Yukun | Chu, Fengyou
We analyze Pb content and Pb isotope ratios in 29 surface sediments and one sediment core from the eastern Beibu Gulf, Southern China. The results indicate that obvious Pb enrichment was limited to the oil and gas exploration area in the central gulf and the mud deposit in the northern gulf. The enrichment of Pb in sediment core A97 started in the 1860s, but a notable drop of Pb content occurred in the 1970s, suggesting variations in human activity. The Pb isotope ratios in sediments were very similar to those in natural sources, except for the sediments near the oil platform, which may be polluted by anthropogenic input. Sediments with relatively high radiogenic Pb isotope compositions may be mainly sourced from northern coast of Beibu Gulf, sediment flux through Qiongzhou Strait, or the Red River, while the coastal zone of western Hainan Island and nearby bottom erosion area produce as minor provenances.
Mostrar más [+] Menos [-]Marine litter on the Baltic seafloor collected by the international fish-trawl survey Texto completo
2019
Zablotski, Yury | Kraak, Sarah B.M.
Marine litter on the Baltic seafloor collected by the international fish-trawl survey Texto completo
2019
Zablotski, Yury | Kraak, Sarah B.M.
Marine litter is a global concern. Since most of the litter sinks, understanding the composition of benthic marine litter is crucial for addressing this concern. However, high costs of seafloor monitoring inhibit such understanding. Consequently, benthic marine litter in the Baltic Sea has not been comprehensively addressed yet. Here we present data from 2377 hauls, which collected 6828 litter items and 2412 kg on the Baltic seafloor during six years of the Baltic International Trawl Survey (BITS) by seven nations. Our results show lower percentages of plastic (35%) than the widely cited world average (70%) and less fishery-originated litter (2.2–5.6%) than was previously reported for the Baltic Sea (4–24%). Natural products, mostly residuals of burnt coal, were identified as the most common litter category (42–57%) and were largely ignored in the past. Our results highlight the importance of using several evaluation metrics, particularly number of items, weight and encounter probability.
Mostrar más [+] Menos [-]Marine litter on the Baltic seafloor collected by the international fish-trawl survey Texto completo
2019
Zablotski, Yury | Kraak, Sarah B. M.
Marine litter is a global concern. Since most of the litter sinks, understanding the composition of benthic marine litter is crucial for addressing this concern. However, high costs of seafloor monitoring inhibit such understanding. Consequently, benthic marine litter in the Baltic Sea has not been comprehensively addressed yet. Here we present data from 2377 hauls, which collected 6828 litter items and 2412 kg on the Baltic seafloor during six years of the Baltic International Trawl Survey (BITS) by seven nations. Our results show lower percentages of plastic (35%) than the widely cited world average (70%) and less fishery-originated litter (2.2–5.6%) than was previously reported for the Baltic Sea (4–24%). Natural products, mostly residuals of burnt coal, were identified as the most common litter category (42–57%) and were largely ignored in the past. Our results highlight the importance of using several evaluation metrics, particularly number of items, weight and encounter probability.
Mostrar más [+] Menos [-]Insensitivities of a subtropical productive coastal plankton community and trophic transfer to ocean acidification: Results from a microcosm study Texto completo
2019
Wang, Tifeng | Jin, Peng | Wells, Mark L. | Trick, Charles G. | Gao, Kunshan
Insensitivities of a subtropical productive coastal plankton community and trophic transfer to ocean acidification: Results from a microcosm study Texto completo
2019
Wang, Tifeng | Jin, Peng | Wells, Mark L. | Trick, Charles G. | Gao, Kunshan
Ocean acidification (OA) has potential to affect marine phytoplankton in ways that are partly understood, but there is less knowledge about how it may alter the coupling to secondary producers. We investigated the effects of OA on phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) under present day (400 μatm) and projected end-of-century (1000 μatm) pCO2 levels. Net primary production was unaffected, although OA did lead to small decreases in growth rates. OA had no measurable effect on micro-/mesozooplankton grazing rates. Elevated pCO2 had no effect on phytoplankton fatty acid (FA) concentrations during exponential phase, but saturated FAs increased relative to the control during declining phase. FA profiles of mesozooplankton were unaffected. Our findings show that short-term exposure of plankton communities in eutrophic subtropical waters to projected end-of-century OA conditions has little effect on primary productivity and trophic linkage to mesozooplankton.
Mostrar más [+] Menos [-]Seawater carbonate chemistry and phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) Texto completo
2019
Wang, Tifeng | Jin, Peng | Wells, Mark L | Trick, Charles G | Gao, Kunshan
Ocean acidification (OA) has potential to affect marine phytoplankton in ways that are partly understood, but there is less knowledge about how it may alter the coupling to secondary producers. We investigated the effects of OA on phytoplankton primary production, and its trophic transfer to zooplankton in a subtropical eutrophic water (Wuyuan Bay, China) under present day (400 μatm) and projected end-of-century (1000 μatm) pCO2 levels. Net primary production was unaffected, although OA did lead to small decreases in growth rates. OA had no measurable effect on micro-/mesozooplankton grazing rates. Elevated pCO2 had no effect on phytoplankton fatty acid (FA) concentrations during exponential phase, but saturated FAs increased relative to the control during declining phase. FA profiles of mesozooplankton were unaffected. Our findings show that short-term exposure of plankton communities in eutrophic subtropical waters to projected end-of-century OA conditions has little effect on primary productivity and trophic linkage to mesozooplankton.
Mostrar más [+] Menos [-]Spatial variations of arsenic and heavy metal pollutants before and after the water-sediment regulation in the wetland sediments of the Yellow River Estuary, China Texto completo
2019
Cheng, Qingli | Zhou, Weifeng | Zhang, Jing | Shi, Lei | Xie, Yifei | Li, Xudong
To investigate the effects of the water-sediment regulation on the spatial variations of metals in the surface sediments of the Yellow River Estuary (YRE), sampling sites were set in 2015 (51 sites in June and 33 in October). The content of Cu, Pb, Cd, Cr, Zn, Ni and Mn was determined using inductively coupled plasma spectrometry and of Hg and As atomic fluorescence spectrometry. The results showed that the concentrations of metals in the sediments of YRE were lower after the regulation, while that of most metals increased in the tidal areas of the current estuary with fine particles. Environmental pollution and ecological risk of metals were mainly from Hg and Cd. Metals carried with the silt of the river should be focused. The findings were expected to update the current status of metal pollution of YRE and be helpful for the delicacy management of the regime and silt-laden rivers.
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