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1.
S. V. Panno  W. R. Kelly   《Journal of Hydrology》2004,290(3-4):229-242
This investigation was designed to estimate the mass loading of nitrate (NO3−) and herbicides in spring water discharging from groundwater basins in an agriculturally dominated, mantled karst terrain. The loading was normalized to land use and NO3− and herbicide losses were compared to estimated losses in other agricultural areas of the Midwestern USA. Our study area consisted of two large karst springs that drain two adjoining groundwater basins (total area of 37.7 km2) in southwestern Illinois' sinkhole plain, USA. The springs and stream that they form were monitored for almost 2 years. Nitrate–nitrogen (NO3–N) concentrations at three monitoring sites were almost always above the background concentration (1.9 mg/l). NO3–N concentrations at the two springs ranged from 1.08 to 6.08 with a median concentration of 3.61 mg/l. Atrazine and alachlor concentrations ranged from <0.01 to 34 μg/l and <0.01 to 0.98 μg/l, respectively, with median concentrations of 0.48 and 0.12 μg/l, respectively. Approximately 100,000 kg/yr of NO3–N, 39 kg/yr of atrazine, and 2.8 kg/yr of alachlor were discharged from the two springs. Slightly more than half of the discharged NO3− came from background sources and most of the remainder probably came from fertilizer. This represents a 21–31% loss of fertilizer N from the groundwater basins. The pesticide losses were 3.8–5.8% of the applied atrazine, and 0.05–0.08% of the applied alachlor. The loss of atrazine adsorbed to the suspended solid fraction was about 2 kg/yr, only about 5% of the total mass of atrazine discharged from the springs.  相似文献   

2.
A case study on fuel oil contamination in a mangrove swamp in Hong Kong   总被引：5，自引：0，他引：5  
Tam NF  Wong TW  Wong YS 《Marine pollution bulletin》2005,51(8-12):1092-1100
Mangroves commonly found along tropical and subtropical coastlines are susceptible to oil pollution. In December 2000, around 500 1 m tall Kandelia candel saplings at the age of 3–5 years old located at the foreshore region of Sheung Pak Nai swamp, Hong Kong SAR, were found to be damaged by oil pollution. More than 80% of the saplings were either dead or washed away and leaving less than 5% healthy saplings with dense green leaves. Elevated concentrations of light n-alkanes (ranging from n-C14 to n-C20), pristane and phytane were recorded in surface sediments collected in December 2000. The ratio between light and total n-alkanes was 0.4. The total petroleum hydrocarbons (60–80 μg g−1 TPH) and unresolved complex mixtures (60–70 μg g−1 UCM) were higher than the background values of other mangrove sediments in Hong Kong, which were 40 and 20 μg g−1, respectively. In certain root zone sediments, TPH concentrations were above 1000 μg g−1. These results suggest that surface sediments in Sheung Pak Nai were contaminated by petroleum oil, most likely by illegal discharge of fuel oil which occurred between 1998 and 2002. One year later, in December 2001, unhealthy saplings had recovered and re-grown. The concentrations of TPH and UCM in sediments declined to around 40 μg g−1, pristane and phytane dropped by 80%, and the ratio of light to total n-alkanes was 0.15, suggesting that residual oil in sediments was weathered leading to a remarkable recovery of the unhealthy saplings.  相似文献   

3.
Concentrations of the sum of 15 PAHs in 22 surficial sediment samples from the western Irish Sea ranged from below 100 ng g−1 in sandy sediments to a maximum of 1422 ng g−1 in the centre of the mud basin. The concentrations are typical of coastal shelf sediments, but greater than those observed for aquatic sediments remote from known anthropogenic sources. Organic C and the % sediment <15 μm were positively correlated with ΣPAH. ΣPAH was normalised to organic C and particle size (i.e. expressed as ΣPAH/Corg and ΣPAH/%<15 μm) and significant relationships were still observed with organic C and %<15 μm. The results are discussed in the context of using organic C to normalise concentrations of PAHs to assess contamination levels in sediments.  相似文献   

4.
Sodium bromide and Rhodamine WT were used as conservative tracers to examine the hydrologic characteristics of seven tundra streams in Arctic Alaska, during the summers of 1994–1996. Continuous tracer additions were conducted in seven rivers ranging from 1st to 5th order with samples collected from instream, hyporheic, and parafluvial locations. Tracer data was used as input for a computer model to estimate hydrologic characteristics of each study reach. While solute concentrations during the tracer additions indicated that steady-state or “plateau” conditions had been reached, interstitial samples indicated that there were additional hyporheic and parafluvial zones that had not been fully labeled at the time of apparent steady state in the stream channel (plateau). Exchange between channel and hyporheic water was a function of location within a pool–riffle sequence, with rapid downwelling at the head of riffles and delayed upwelling in riffle tails. The extent of exchange between channel and hyporheic water was positively correlated with apparent streambed hydraulic conductivity. Tracer additions indicated interstitial velocities ranging from 0.030 to 0.075 cm s−1 and hydraulic conductivities from 2.4 to 12.2 cm s−1. Hyporheic and in-channel samples were collected for N, P, DO, and CO2 analyses in conjunction with conservative tracer additions in four of the stream reaches for which the interstitial velocities were also determined. Transformation rates based on these data indicated that there was rapid nitrification of mineralized organic N and production of ammonium, phosphate, and carbon dioxide in the interstitial zones of all four reaches. Dissolved oxygen did not appear to be limiting in the reaches studied. The hyporheic zone of all four reaches was a source of nitrate, carbon dioxide, and ammonium to the channel water based on the average concentration of upwelling waters. Increased contact time with hyporheic and parafluvial zones was related to decreased temperature and increased conductivity. Net nitrogen flux from the hyporheic zone was equivalent to 14–162% of benthic N uptake requirements for the Kuparuk River. These observations are important because we expected that the presence of continuous permafrost in this Arctic environment would limit the importance of hyporheic processes, either physically (i.e., through the presence of a restricting thaw bulb in the permafrost) or biogeochemically (i.e., through low temperatures). Instead, we found that biogeochemical processes in the hyporheic zone of these Arctic streams are at least as important as it is in similar temperate stream ecosystems.  相似文献   

5.
本文利用2012年4月30日至5月10日华北地区大气湍流实验资料,分析了冬小麦田下垫面温度、湿度、二氧化碳(CO2)和甲烷(CH4)的湍流统计和输送特征,利用涡旋相关法计算的CH4通量值确定了松弛涡旋累积(REA)法计算CH4通量的经验系数.结果表明,不稳定层结下,温度、湿度、CO2和CH4的归一化标准差随稳定度参数z/L的关系满足-1/3幂次关系.热量、水汽和CO2水平方向的湍流输送和垂直方向的比值与稳定度参数z/L存在一定的相关关系,但CH4没有类似特征.实验期间,感热通量数值较低,潜热通量较高;CO2在夜间表现出微弱的向上输送,其余时段为向下输送,可以认为实验站所在地区是碳汇;CH4的湍流输送整体为向下输送,无明显的日变化规律,可以认为是CH4汇.利用松弛涡旋累积法获取CO2和CH4通量的参数取值分别为0.61和0.30.  相似文献   

6.
Germination inhibition of the marine macrophyte Phyllospora comosa was utilized as a sub-lethal end-point to assess and compare the effects of four oil dispersants and dispersed diesel fuel and crude oil combinations. Inhibition of germination by the water-soluble fraction of diesel fuel increased following the addition of each of the dispersants; the nominal 48-h EC50 concentration of diesel fuel declined from 6800 to approximately 400 μl l−1 nominal for each dispersed combination. This contrasted with crude oil, where the addition of two dispersants resulted in an enhanced germination rate and an increase in nominal EC50 concentrations from 130 μl l−1 for the undispersed crude to 4000 and 2500 μl l−1. The results indicate that, while germination inhibition of P. comosa may be enhanced by the chemical dispersal of oil, the response varies with type of both oil and oil dispersant.  相似文献   

7.
The water quality of rivers in the eastern part of the Humber Basin, north-eastern England is described from a baseflow survey (11–13 August 2006) of a wide range of water quality determinants, and long-term nutrient records of the Environment Agency of England and Wales (EA). The baseflow survey shows that the rivers are oversaturated with respect to dissolved CO2 and calcite. They are sodium, potassium, lithium, boron, chloride, sulphate and fluoride bearing from a combination of atmospheric, within-catchment, agricultural and sewage effluent sources. Nitrate concentrations are uniform for rivers draining permeable bedrock but decrease for clay drainage areas. Soluble reactive phosphorus (SRP) concentrations are variable across the catchments reflecting the importance and variability of point sources and within-river processing. The EA data show annual oscillations for both NO3 and SRP concentrations. Average NO3 concentrations vary between 3.3 and 18.8 mgN/l and concentrations are low during the summer months. Average SRP concentrations vary between 23 and 1959 μg/l. Highest SRP concentrations generally occur when there is effluent input from sewage treatment works and agricultural point sources (e.g. overflow from slurry tanks, farmyard washings). Despite many of the rivers being nutrient rich, they are generally of good biological quality when point source inputs are not important.  相似文献   

8.
We investigated the distribution of naturally occurring geochemical tracers (222Rn, 223Ra, 224Ra, 226Ra, CH4, δ18O, and δ2H) in the water column and adjacent groundwater of Mangueira Lagoon as proxies of groundwater discharge. Mangueira Lagoon is a large (90 km long), shallow (4–5 m deep), fresh, and non-tidal coastal lagoon in southern Brazil surrounded by extensively irrigated rice plantations and numerous irrigation canals. We hypothesized that the annual, intense irrigation for rice agriculture creates extreme conditions that seasonally change groundwater discharge patterns in the adjacent lagoon. We further supposed that dredging of irrigation canals alters groundwater fluxes.

While the activities of 222Rn in shallow groundwater were 2–3 orders of magnitude higher than in surface water, CH4 and radium isotopes were only 1 order of magnitude higher. Therefore, 222Rn appears to be the preferred groundwater tracer in this system. Radon concentrations and conductivities were dramatically higher near the pump house of rice irrigation canals, consistent with a groundwater source. Modeling of radon inventories accounting for total inputs (groundwater advection, diffusion from sediments, and decay of 226Ra) and losses (atmospheric evasion, horizontal mixing and decay) indicated that groundwater advection rates in the irrigation canals (25 cm/d) are over 2 orders of magnitude higher than along the shoreline (0.1 cm/d). Nearly 75% of the total area of the canals is found in the southern half of the lagoon, where groundwater inputs seem to be higher as also indicated by methane and stable isotope trends. In spite of the relatively small area of the canals, we estimate that they contribute nearly 70% of the total (57,000 m3/d) groundwater input into the entire Mangueira Lagoon. We suggest that the dredging of these canals cut through aquitards which previously restricted upward advection from the underlying permeable strata. The irrigation channels may therefore represent an important but previously overlooked source of nutrients and other dissolved chemicals derived from agricultural practices into the lagoon.  相似文献   


9.
DET (diffusive equilibrium in thin films) gel probes were used for sampling river-bed sediment porewaters, to characterise in situ soluble reactive phosphorus (SRP) concentration profiles and fluxes. DET probes were deployed in three contrasting rural streams: (1) a headwater ‘pristine’ stream, with minimal P inputs from low intensity grassland and no point sources, (2) an intensively cultivated arable catchment, and (3) a stream subject to high P loadings from sewage effluent and intensive arable farming. The DET results showed highly enriched porewater SRP concentrations of between ca. 400 and 5000 μg-P l−1 in the sewage-impacted stream. In contrast, the arable and pristine streams had porewater SRP concentrations <70 μg-P l−1 and <20 μg-P l−1, respectively. Porewater SRP concentration profiles in both the sewage-impacted and arable-impacted streams showed well-defined vertical structure, indicating internal sources and sinks of SRP within the sediment. However, there was little variability in porewater SRP concentrations in the pristine stream. The DET porewater profiles indicated net diffusion of SRP (a) from the overlying river water into the surface sediment and (b) from subsurface sediment upwards towards the sediment–water interface. A mass balance for the sewage-impacted site showed that the influx of SRP into the surface sediments from the overlying river water was small (ca. 1% of the daily river SRP load). The DET results indicated that, in the arable and sewage-impacted streams, the surface ‘cap’ of fine sediment may play an important role in inhibiting upward movement of SRP from subsurface porewaters into the overlying river water, under steady-state, low-flow conditions.  相似文献   

10.
This study examined the effect of copper on the settlement success of planula larvae of the reef-building coral Acropora tenuis during 1994 and 1996 at Magnetic Island, Great Barrier Reef. Copper concentrations of 2, 10, 20 μg l−1 did not inhibit larval settlement after 48-h exposure. However, copper concentrations of 42 μg l−1 and 81 μg l−1 significantly reduced settlement success of A. tenuis larvae after 48-h exposure compared with controls using normal seawater. At 200 μg l−1 copper, all larvae died. EC50 values for the effect of copper on A. tenuis larval settlement were calculated from the 1996 results using measured copper concentrations. The 48-h EC50 was 35 μg l−1 with an upper and lower 95% confidence limit of 37 μg l−1 and 32 μg l−1, respectively. The 48-h NOEC value for both experiments was 20 μg l−1 copper. These experiments provide some of the first data on sub-lethal effects of trace metals on tropical marine organisms, and demonstrate that relatively low copper concentrations impair or inhibit settlement of coral larvae.  相似文献   

11.
Spatial and temporal measurements of shallow sub-surface soil physical properties were made within a 1 km2 upland catchment. The surface soil layer of the catchment was organic rich (>70% organic matter) with a corresponding total porosity of 81%. Monthly point observations of volumetric water content (θ) were combined with point estimates of total porosity () and the porosity <50 μm (residual), to define the ratio of water filled pore volume:pore volume in pores <50 μm (=θ/residual). Values of θ/residual were compared with discharge to test whether mass flow occurred when θ/residual>1. A correlation between water content and discharge was found, with discharge increasing rapidly when θ/residual approached unity. Similar relationships between water content and catchment discharge were identified for soil units adjacent to the stream when θ/residual approached unity. These data suggest that soil pores >50 μm are of crucial importance in determining catchment discharge. Spatial and temporal variations in soil properties related to moisture content of the soil were also observed. Under dry conditions, a clear division based on aspect was noted, the west-facing side of the catchment being wettest. In wetter months, total porosity and soil water content were significantly affected by soil type and the spatial pattern of soil water content was more variable than in the dryer months. The physical quantification of soil properties in the shallow sub-surface layer proved important in explaining different initial changes in discharge from the catchment in response to a rainfall event.  相似文献   

12.
Input and distribution of linear alkylbenzenesulphonates (LAS) in the highly stratified Krka River estuary were studied during 1990–1991. Determinations of individual LAS homologues in wastewater and estuarine waters were performed using reversed-phase high-performance liquid chromatography (HPLC) with spectrofluorimetric detection. The investigated municipal wastewaters contained LAS homologues with alkyl-chain lengths from C10 to C13 at total concentrations in the range of 285–1041 μg l−1. Total LAS input via wastewaters into ibenik Harbour, the most polluted part of the estuary, was estimated at 12.6 kg day−1. A relatively large fraction of total LAS, depending on the wastewater particle load, was found in particulate form (11–59%). Distributions of the individual homologues in dissolved and particulate fractions were rather different, the latter being significantly enriched in higher homologues (C12, C13). The LAS concentration in the estuary was quite low (0.2–23.9 μg l−1) which was caused chiefly by a strong and fast dilution process. However, characteristic vertical distribution of LAS in the estuarine water column indicated that the wastewater plume spreads almost exclusively in the upper (brackish) layer. The concentration maxima were observed in the surface microlayer and at the brackish water/seawater boundary.  相似文献   

13.
In the present work, we built a mathematical model of polychlorinated biphenyl (PCB) bioaccumulation in Perna viridis, namely, a one-compartment model with a time dependent incorporation rate R (μg g−1 lipid per ppb water per day), with positive substrate cooperativity as the underlying physical mechanism. The temporal change of the PCB concentration Q (μg g−1 lipid) in the soft tissues of the mussel depends on the competition of the input rate RW and the output rate kQ, where W is the concentration of PCB in water (ppb water) and k is the elimination rate (per day). From our experimental data, k=0.181±0.017 d−1. The critical concentration in water Wc for positive substrate cooperativity was found to be 2.4 ppb. Below Wc, R is a constant. For a water concentration of 0.5 ppb Aroclor 1254, R=24.0±2.4 μg g−1 lipid ppb−1 d−1. Above Wc, positive substrate cooperativity comes into effect and R becomes a function of time and dependent on the concentration Q in a form R=γQ/(Q+δ). This is the case for a water concentration of 5 ppb Aroclor 1254, where γ=15.1 μg g−1 lipid ppb−1 d1 and δ≈200 μg g−1 lipid. From this model, the uptake is exponentially increasing when the PCB concentration in the mussel is small compared to 200 μg g−1 lipid, and hyperbolically increasing when the concentration is large compared to 200 μg g−1 lipid, which are consistent with the experimental data. The model is useful for understanding the true processes taking place during the bioaccumulation and for risk assessment with higher confidence. Future experimental data which challenge the present model are anticipated and in fact desirable for improvement and perfection of the model.  相似文献   

14.
Bivalves (Crassostrea rizhophorae, Isognomon alatus, Codakia orbicularis Linné, and Tellina fausta) and sediment samples collected from 12 locations along the Dominican Republic coastline were used to assess the degree of nearshore contamination by selected chlorinated hydrocarbons and heavy metals. Concentrations of total chlordanes, DDTs and PCBs ranged from 0.51 to 7.47 ng/g, < MDL to 30.9 ng/g and 11.3 to 82.3 ng/g, and from < MDL to 1.73 ng/g, 0.21 to 12.5 ng/g and 0.46 to 41.9 ng/g in bivalves and surface sediments, respectively. The concentration ranges of predominantly anthropogenic Cu, Pb and Zn were 3.08–866 μg/g, 0.08–1.46 μg/g and 22.9–4380 μg/g in bivalve soft parts and 1.01–111 mg/g, 0.420–134 μg/g and 1.96–277 μg/g in surface sediments, respectively. Mercury concentrations ranged from 0.290 to 7.02 μg/g and from 0.096 to 0.565 μg/g in both matrices. The relatively high Hg concentrations found in bivalves from two stations in Bahia Samana, near to a known source of past Hg contamination in the sediments, require a more in-depth survey of the area. In general the concentrations of selected chlorinated hydrocarbons and trace metals, compared with those reported for the same matrices in the Caribbean and west Atlantic coastal areas, show at present the existence of only very localized contamination problems in the Dominican Republic.  相似文献   

15.
耿飞  孟庆岩  魏鸣  卢显 《地震学报》2017,39(3):386-394
为研究地震活动与大气甲烷浓度时空演变之间的关系,以芦山MS7.0地震为例,基于极轨卫星AQUA上搭载的卫星大气红外探测器(AIRS)获取的甲烷数据产品,通过背景值差值法对该地震前后甲烷柱浓度信息、垂直浓度廓线信息及长时间序列变化信息进行提取,挖掘芦山地震前后甲烷异常排放的时空演化特征.结果表明:2013年1—4月芦山震中区存在明显的甲烷浓度升高;甲烷浓度时空演化趋势为初始排放→激增扩散→聚敛加强→相对减弱→震后排放→回复平静;震前震中区甲烷柱浓度为该地区2008年1月—2016年8月异常最显著的时段.因此认为芦山MS7.0地震前甲烷排放浓度升高现象或为该地震的前兆信息.   相似文献   

16.
The composition and spatial distribution of aliphatic and polycyclic aromatic hydrocarbons (PAHs) were investigated in biota and coastal sediments from four countries surrounding the Gulf (Bahrain, Qatar, United Arab Emirates and Oman). The levels of total petroleum hydrocarbons (TPH), aliphatic unresolved mixture and PAHs in sediments and biota were relatively low compared to world-wide locations reported to be chronically contaminated by oil. Only in the case of the sediments collected near the BAPCO oil refinery in Bahrain, having concentrations of 779 μg g−1 total petroleum hydrocarbon equivalents and 6.6 μg g−1 ∑PAHs, can they be categorized as chronically contaminated. Some evidence of oil contamination was also apparent in sediments and bivalves around Akkah Head and Abu Dhabi in the UAE, and near Mirbat in Oman. Contaminant patterns in sediments and biota indicated that the PAHs were mainly from fossil sources, with the exception of the high PAH concentrations in sediments near the BAPCO refinery that contained substantial concentrations of carcinogenic PAH combustion products.  相似文献   

17.
The impact and recovery from exposure to the herbicide diuron [DCMU; 3-(3′,4′-dichlorophenyl)-1,1-dimethylurea] was assessed for three tropical seagrasses, maintained in outdoor aquaria over a 10-day period. Photosynthetic stress was detected using chlorophyll a fluorescence, measured with a Diving-PAM (pulse amplitude modulated fluorometer). Exposure to 10 and 100 μg l−1 diuron resulted in a decline in effective quantum yield (ΔF/Fm′) within 2 h of herbicide exposure in Cymodocea serrulata, Halophila ovalis and Zostera capricorni. Effective quantum yield also declined over the first 24 h of exposure in H. ovalis at even lower diuron concentrations (0.1 and 1.0 μg l−1). Effective quantum yield in H. ovalis and Z. capricorni was significantly depressed at all diuron concentrations (0.1–100 μg l−1) after 5 days exposure, whereas effective quantum yield in C. serrulata was only significantly lower in plants exposed to highest diuron concentrations (10 and 100 μg l−1). Effective quantum yield depression was present 5 days after plants exposed to 10 and 100 μg l−1 diuron were returned to fresh seawater. These results indicate that exposure to herbicide concentrations present in nearshore Queensland sediments present a potential risk to seagrass functioning.  相似文献   

18.
We have determined the production yields for radionuclides in Al2O3, SiO2, S, Ar, K2SO4, CaCO3, Fe, Ni and Cu targets, which were irradiated with slow negative muons at the Paul Scherrer Institute in Villigen (Switzerland). The fluences of the stopped negative muons were determined by measuring the muonic X-rays. The concentrations of the long-lived and short-lived radionuclides were measured with accelerator mass spectrometry (AMS) and γ-spectroscopy, respectively. Special emphasis was put on the radionuclides 10Be, 14C and 26Al produced in quartz targets, 26Al in Al2O3 and S targets, 36Cl in K2SO4 and CaCO3 targets, and 53Mn in Fe2O3 targets. These targets were selected because they are also the naturally occurring target minerals for cosmic ray interactions in typical rocks. We also present results of calculations for depth-dependent production rates of radionuclides produced after cosmic ray μ− capture, as well as cosmic ray-induced production rates of geologically relevant radionuclides produced by the nucleonic component, by μ− capture, by fast muons and by neutron capture.  相似文献   

19.
Tributyltin (TBT) concentrations in waters of Poole Harbour ranged between 2–139 ng l−1 (as Sn) and increased to 234–646 ng l−1 within marinas. Seasonal trends in contamination coincided with boat usage patterns and peaked during summer months. A combination of poor tidal flushing and removal of TBT to particulates restricts high levels of contamination to areas closest to marinas and moorings; TBT concentrations in benthic sediments decreased from 0.52 μg g−1 near such sites to 0.02 μg g−1 at the harbour mouth. Organotin accumulations in several benthic invertebrates including polychaetes (Nereis diversicolor), snails (Littorina littorea) and clams (Scrobicularia plana, Mya arenaria) reflect the distribution of contamination in the environment, though concentration factors (relative to water) vary considerably between species and were highest in sediment dwelling clams, notably Mya (1.3×105). Compared to organotins, biological availability of inorganic tin is low.

Levels of TBT in parts of Poole Harbour exceed Environmental Quality Targets designed to protect marine life and may be responsible for poor recruitment, particularly in bivalves, at heavily contaminated sites.  相似文献   


20.
Pesticides and herbicides including organochlorine compounds have had extensive current and past application by Queensland's intensive coastal agriculture industry as well as for a wide range of domestic, public health and agricultural purposes in urban areas. The persistent nature of these types of compounds together with possible continued illegal use of banned organochlorine compounds raises the potential for continued long-term chronic exposure to plants and animals of the Great Barrier Reef. Sediment and seagrass samples were collected from 16 intertidal and 25 subtidal sampling sites between Torres Strait and Townsville, near Mackay and Gladstone, and in Hervey and Moreton Bays in 1997 and 1998 and analysed for pesticide and herbicide residues. Low levels of atrazine (0.1–0.3 μg kg−1), diuron (0.2–10.1 μg kg−1), lindane (0.08–0.19 μg kg−1), dieldrin (0.05–0.37 μg kg−1), DDT (0.05–0.26 μg kg−1), and DDE (0.05–0.26 μg kg−1) were detected in sediments and/or seagrasses. Contaminants were mainly detected in samples collected along the high rainfall, tropical coast between Townsville and Port Douglas and in Moreton Bay. Of the contaminants detected, the herbicide diuron is of most concern as the concentrations detected have some potential to impact local seagrass communities.  相似文献   

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