Waters Of Taiwan Research Articles

Effect modification of the association between nitrates and rectal cancer by drinking water hardness: evidence from an ecological study

Background and Aims: The objectives of this study were to (1) examine the relationship between nitrate levels in public water supplies and increased risk of death from rectal cancer and (2) determine whether calcium (Ca) and magnesium (Mg) levels in drinking water might modify the effects of nitrate on development of rectal cancer. Methods: A matched case-control study was used to investigate the relationship between the risk of death from rectal cancer and exposure to nitrate in drinking water in Taiwan. All rectal cancer deaths of Taiwan residents from 2003 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth, and year of death. Information on the levels of nitrate-nitrogen (NO3-N), Ca, and Mg in drinking water was collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cancer cases and controls was presumed to be the source of the subject’s NO3-N, Ca, and Mg exposure via drinking water. Results: Relative to individuals whose NO3-N exposure level was <0.38 ppm, the adjusted odds ratio (OR) (95% CI) for rectal cancer occurrence was 1.15 (1.01-1.32) for individuals who resided in municipalities served by drinking water with a NO3-N exposure > or =0.38 ppm. There was no apparent evidence of an interaction between drinking water NO3-N levels with low Mg intake via drinking water. However, evidence of a significant interaction was noted between drinking-water NO3-N concentrations and Ca intake via drinking water. Conclusions: Our findings showed that the correlation between NO3-N exposure and risk of rectal cancer development was influenced by Ca in drinking water. This is the first study to report effect modification by Ca intake from drinking water on the association between NO3-N exposure and risk of rectal cancer occurrence. Increased knowledge of the mechanistic interaction between Ca and NO3-N in reducing rectal cancer risk will aid in public policymaking and setting threshold standards.

Study on the wave climate variation to the renewable wave energy assessment

To reduce the dependence on fossil fuel and imported energy resources, Taiwan has ever-increasing needs of renewable energy. With the rapid development of the technologies of wave energy converter, the wave energy source will be able to meet parts the demand. The Energy Research Laboratories of the Industrial Technology Research Institute, Taiwan (2005), based on the statistic of one-year wave data, stated that the mean wave energy at the northeast coast of Taiwan reaches 11.56 kW/m, giving it the potential of wave power utilization. However, one of the major obstacles with the wave energy utilization is lack of long-term ocean wave measurements. The long-term variations in wave parameters impose changes in wave energy converter outputs. Lack of long-term data makes it difficult to assess the cost-benefit of wave energy conversion projects for the policy and decision makers. The present study aims to quantitatively evaluate the wave climate variations of the northwestern Pacific and the Taiwan Waters based on long-term wave data base. Wave observations around Taiwan have been performed since 1998, thus, earlier data of wave climate are not available. This study reconstructs the wave data of the northwest Pacific over the past three decades based on the SWAN numerical wave model that driven by NECP global reanalysis wind fields. The simulation results are compared and validated with measured data. The results show that the long-term wave climate variations around Taiwan consist of oscillations of three different periods, i.e. the seasonal, inter-annual and decade oscillations. The seasonal oscillation has significant amplitude that leads the wave energy one order magnitude greater in winter than in summer. In addition to seasonal changes, the wave energy features inter-annual variations, which are highly related to the El Nino and La Nina phenomena. In the La Nina years, the annual averaged wave energy could be double than in El Nino years. Finally, this study adopted the Man-Kendall Non-Parametric Test and the Hilbert Huang EMD method to analyze the long-term wave variation trends. The results showed that the wave height experienced climbing trends during 1976–1985 and 1997–2006, and a descending trend during 1985–1997. The reasons for wave climate oscillations in the decadal variation should be further investigation.

Occurrence and fate of pharmaceuticals and personal care products in Taiwan's aquatic environment

Pharmaceuticals and personal care products (PPCPs) have raised considerable concern around the world due to their potential toxicity for ecological system and human health. PPCPs are ineffectively removed by conventional wastewater treatment processes and thus occur widely in aqueous environments. This study investigated the occurrence and removal of 28 often-used PPCPs (including selected antibiotics, estrogens, non-steroidal anti-inflammatory drugs, beta-blockers, and lipid regulators) in the primary, secondary and tertiary (ultrafiltration/reverse osmosis (UF/RO)) treatment processes of the Water Resource Recycling Center (WRRC) and surface waters in Taiwan. We have demonstrated 20 target PPCPs in WRRC influents; sulfamethoxazole (1353 ng/L), caffeine (6823 ng/L) and acetaminophen (2716 ng/L) were found at high concentrations. Secondary and chlorination processes showed inefficient removal for PPCPs (12 PPCPs had <80% removal). However, most target compounds were removed effectively (with ~90% removal) in the tertiary process (UF/RO) except for oxytetracycline and caffeine, and the overall removal efficiency by WRRC was >99%. More than 10 compounds were detected in the surveyed surface waters (from reservoirs, river waters and dams). Caffeine had the highest observed concentration (1,813 ng/L) while others were present at <260 ng/L. Sulfamethoxazole, sulfamethazine, sulfadimethoxine and caffeine were detected most frequently (>70%). Some of the PPCPs found originated from discharges from conventional wastewater treatment plants. In conclusion, RO demonstrated good overall performance and could be used to process wastewater to better ensure the health of humans and wildlife.

Performance of a 270,000 CMD integrated membrane system for water supply in Taiwan

This paper presents an integrated membrane system (IMS) designed, installed by KINTECH Technology Co. Ltd. and its long term performance at Kaotan Water Treatment Plant (KTWTP). The IMS installed at KTWTP is the first membrane system as well as the first IMS for tap water production in Taiwan. The raw waters from Kaoping River, local subsurface flow and groundwater were pumped into KTWTP for the tap water supply of Kaohsiung area. Turbidity of water in the Kaoping River during the typhoon usually increases abruptly up to 5,000–10,000 NTU, greatly surpassing the upper limit of 1,500 NTU for conventional purification to be effective. In addition, field data also showed that the levels of ammonia-nitrogen, total hardness, total dissolved solid and certain inorganic constituents in local groundwater are too high to be effectively removed by conventional system. The KTWTP was established by Taiwan Water Corporation (TWC) in 1972 and initially operated on conventional process. To meet increasingly stringent drinking water standards set by Taiwan EPA, KTWTP was upgraded in 2007 by integrating IMS (ultrafiltration, nanofiltration and reverse osmosis) into the conventional system. A two-year monitoring survey of UF-NF-RO integrated membrane system at KTWTP showed that the treated water quality is far beyond expectation as well as the substantial accomplishment of the IMS process control and data processing resulted in an excellent performance of the integrated membrane system.

Inhella fonticola sp. nov., isolated from spring water, and emended description of the genus Inhella

A yellow-pigmented bacterial strain designated TNR-25(T) was isolated from spring water in Taiwan and was characterized using a polyphasic taxonomic approach. Strain TNR-25(T) was gram-negative, obligately aerobic, rod-shaped, non-motile and non-spore-forming. Growth occurred at 15-40 °C (optimum, 25 °C), at pH 6.0-10.0 (optimum, pH 7.0) and with 0-0.5 % NaCl (optimum, 0 %). Phylogenetic analyses based on 16S rRNA gene sequences showed that strain TNR-25(T) belonged to the genus Inhella and its closest neighbour was Inhella inkyongensis IMCC1713(T) with 98.1 % sequence similarity. The major fatty acids (>10 %) of strain TNR-25(T) were summed feature 3 (comprising C(16 : 1)ω7c and/or C(16 : 1)ω6c) and C(16 : 0). The major cellular hydroxy fatty acids were C(10 : 0) 3-OH and C(12 : 0) 3-OH. The isoprenoid quinone was Q-8 and the DNA G+C content was 69.6 mol%. The polar lipid profile consisted of a mixture of phosphatidylethanolamine, phosphatidylglycerol, phosphatidylserine, diphosphatidylglycerol and several uncharacterized phospholipids. The DNA-DNA relatedness between strain TNR-25(T) and I. inkyongensis IMCC1713(T) was about 30.6-35.5 %. On the basis of the genotypic and phenotypic data, strain TNR-25(T) represents a novel species in the genus Inhella, for which the name Inhella fonticola sp. nov. is proposed; the type strain is TNR-25(T) ( = BCRC 80211(T) = LMG 25721(T)).

Survey of Naegleria from Taiwan recreational waters using culture enrichment combined with PCR

Naegleria is a free-living amoeba. Pathogenic Naegleria may pose a health risk to people who come in contact with recreational waters. Here, we used Naegleria culture enrichment with PCR to identify the Naegleria species and investigated the distribution of Naegleria spp. in recreational waters including spring water, stream water and raw domestic water in central and southern Taiwan. In this study, Naegleria spp. were detected in 19 (17.8%) of the water samples. The occurrence of Naegleria in raw domestic water was 28.6%, higher than in stream water (14.7%) and in spring water (6.5%). The most frequently identified species exhibiting the closest phylogenetic relationships to the isolates were N. australiensis (n=4) and N. canariensis (n=4), followed by N. clarki (n=3) and N. philippinensis (n=3); N. americana (n=2). N. lovaniensis, N. dobsoni, and N. gruberi were each detected once. The pathogenic species N. fowleri was not detected, probably due to the low incubation temperature; however, the isolates exhibiting the closest phylogenetic relationships to the pathogenic species in mice of PAM, N. australiensis and N. philippinensis, were found. Results of this survey suggest the distribution of Naegleria spp. excluding N. fowleri in recreational waters. It should be considered a potential threat for health associated with human activities in recreational waters.

Does calcium in drinking water modify the association between nitrate in drinking water and risk of death from colon cancer?

The objective of this study was to explore whether calcium (Ca) levels in drinking water modified the effects of nitrate on colon cancer risk. A matched case-control study was used to investigate the relationship between the risk of death from colon cancer and exposure to nitrate in drinking water in Taiwan. All colon cancer deaths of Taiwan residents from 2003 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth and year of death. Information on the levels of nitrate-nitrogen (NO(3)-N) and Ca in drinking water have been collected from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cases and controls was assumed to be the source of the subject's NO(3)-N and Ca exposure via drinking water. We observed evidence of an interaction between drinking water NO(3)-N and Ca intake via drinking water. This is the first study to report effect modification by Ca intake from drinking water on the association between NO(3)-N exposure and risk of colon cancer mortality.

Isolation and identification of Legionella and their host amoebae from weak alkaline carbonate spring water using a culture method combined with PCR

Legionella were detected with the direct DNA extraction method, Legionella culture method, and free-living amoebae (FLA) culture method from weak alkaline carbonate spring water in Taiwan. Moreover, we also investigated the existence of Acanthamoeba, Hartmannella, and Naegleria, ubiquitous FLA in aquatic environments, to identify the correlations between existing Legionella. This study reports detecting Legionella in 15 of the 51 weak alkaline carbonate spring water samples (29.4%). This work also found five of the 51 samples (9.8%) analyzed by the direct DNA extraction method, three of the 51 (5.9%) samples analyzed by the Legionella culture method, and 11 of the 51 samples (21.6%) evaluated using the FLA culture method to be positive for Legionella. The most frequently identified Legionella species was the Legionella-like amoebal pathogen (n=5), followed by unidentified Legionella spp. (n=4), and Legionella pneumophila (n=4), Legionella fairfieldensis (n=3), and then Legionella rubrilucens (n=2). Legionella waltersii was detected once. The occurrence of Acanthamoeba, Hartmannella, and Naegleria were 5.9% (3/51), 52.9% (27/51), and 5.9% (3/51), respectively. All Hartmannella isolates were identified as Hartmannella vermiformis, and Naegleria isolates were all identified as Naegleria australiensis. The three Acanthamoeba isolates were identified as one Acanthamoeba polyphaga and two Acanthamoeba jacobsi. H. vermiformis (40.7%) were Legionella hosts, including all of the amoebae-resistant Legionella detected in the present study. Therefore, the important correlations between Legionella and H. vermiformis require further clarification. The combined results of this survey confirm that Legionella and FLA are ubiquitous in weak alkaline carbonate spring water in Taiwan.

Copepod species and their trace metal contents in coastal northern Taiwan

Two cruises were carried out to collect copepod samples from the coastal waters of Northern Taiwan, the Taiwan Strait and the southern East China Sea extending to the Okinawa Trough where the Kuroshio waters intrude. The copepod samples were analyzed for community structure and the dominant copepod species were further analyzed for their trace metal concentration. In total, 106 species of copepods, belonging to 22 families and 43 genera, were recorded. The dominant copepod species were Acartia pacifica, Canthocalanus pauper, Cosmocalanus darwini, Undinula vulgaris, Temora discaudata, Temora turbinata, and Oncaea venusta and exhibited a spatial variation among the study areas. The metal concentration ranges for the analyzed copepods were as follows: Cd, 0.39–142 μg/g; Co, 0.03–91.9 μg/g; Cr, 2.26–284 μg/g; Cu, 3.03–196 μg/g; Fe, 19.96–3118 μg/g; Mn, 3.98–994 μg/g; Ni, 1.69–955 μg/g; Pb, 0.04–97.5 μg/g; and Zn, 1.52–1140 μg/g. The same metal content of copepods showed considerable variation between the intra and inter species. The inter species trace metal content sequence was: O. venusta > A. pacifica > C. darwini > T. turbinata > T. discaudata > C. pauper > U. vulgaris. In addition, the copepod metal quota also exhibited spatial variation: coastal water > the southern East China Sea > the Kuroshio Water.

Nitrates in Drinking Water and The Risk of Death from Brain Cancer: Does Hardness in Drinking Water Matter?

The objectives of this study were to (1) examine the relationship between nitrate levels in public water supplies and risk of death from brain cancer and (2) determine whether calcium (Ca) and magnesium (Mg) levels in drinking water might modify the influence of nitrates on development of brain cancer. A matched cancer case-control study was used to investigate the relationship between the risk of death from brain cancer and exposure to nitrates in drinking water in Taiwan. All brain cancer deaths of Taiwan residents from 2003 through 2008 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to cancer cases by gender, year of birth, and year of death. Information on the levels of nitrate-nitrogen (NO3-N), Ca, and Mg in drinking water was obtained from Taiwan Water Supply Corporation (TWSC). The municipality of residence for cancer cases and controls was presumed to be the source of the subject's NO3-N, Ca, and Mg exposure via drinking water. Relative to individuals whose NO3-N exposure level was <0.38 ppm, the adjusted OR (95% CI) for brain cancer occurrence was 1.04 (0.85–1.27) for individuals who resided in municipalities served by drinking water with a NO3-N exposure ≥0.38 ppm. No marked effect modification was observed due to Ca and Mg intake via drinking water on brain cancer occurrence.

Nitrates in Drinking Water and the Risk of Death from Childhood Brain Tumors in Taiwan

The objective of this study was to (1) examine the relationship between nitrate (NO3-N) levels in public water supplies and risk of death from childhood brain tumors (CBT) and (2) determine whether calcium (Ca) and magnesium (Mg) levels in drinking water might modify the effects of NO3-N on development of CBT. A matched cancer case-control study was used to investigate the relationship between the risk of death attributed to CBT and exposure to NO3-N in drinking water in Taiwan. All CBT deaths of Taiwan residents from 1999 through 2008 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cases by gender, year of birth, and year of death. Information on the levels of nitrate-nitrogen (NO3-N), Ca, and Mg in drinking water were collected from Taiwan Water Supply Corporation. The municipality of residence for CBT cases and controls was presumed to be the source of the subject's NO3-N, Ca, and Mg exposure via drinking water. Relative to individuals whose NO3-N exposure level was ≤0.31 ppm, and the adjusted odds ration (OR) (95% confidence interval [CI]) for CBT occurrence was 1.4 (1.07–1.84) for individuals who resided in municipalities served by drinking water with a NO3-N exposure >0.31 ppm. No significant effect modification was observed by Ca and Mg intake via drinking water. Data suggest that exposure to NO3-N in drinking water is associated with a higher risk of CBT development in Taiwan.

PCBs in Donggang River Watershed sediments, Taiwan

Polychlorinated biphenyls (PCBs) were measured in the sediments of the Donggang River Watershed, one of the most polluted bodies of water in southern Taiwan. Field data showed that detectable concentrations of 121 PCB congeners were found and total PCBs were measured in 32 out of 33 samples, and 98 congeners were detected. The total concentrations of PCBs in the sediment ranged from 25.5–63.5 ngg−1 dw with a geometric mean ± standard deviation of 4.00 ± 1.73 ngg−1 dw, with one sample below the detection limit. The highest concentration (20.79 ngg−1 dw) was found at the most downstream sampling site near the head of the estuary, while average levels were highest at the tributary sampling site, ranging from 8.81–019.4 ngg−1 dw. In general, the average concentrations in the tributary sampling sites were higher than those in the main stem sampling sites, which were 24.02 ± 10.15 and 19.97 ± 8.9 ngg−1 dw, respectively. Among the 121 congeners, congener 1, 3, 22, 25, 33, 21, 53, 47, 41, 64, 71, 107, 136, 146, 158, 157, 200, 172, 189, 207, 205, 206, and 209 were all below the detection limit and were not found in any samples. Congeners 191, 85, and 26 were the most commonly detected, however, PCB 26, 12+13, and 52 were the most abundant congeners and contributed 11.5, 8.4, and 6.96% to the total PCBs, respectively. The results indicated that trace PCBs were still detectable in the sediment of the Donggang River and its tributaries. However, the concentrations were considerably lower than those found in other studies of nearby areas in Taiwan and around the world.

Zooplankton assemblages as indicators of seasonal changes in water masses in the boundary waters between the East China Sea and the Taiwan Strait

Hydrology and trophic relationships are frequently reported for inducing changes in mesozooplankton communities. This study investigated the distribution and abundance of mesozooplankton in the boundary waters between the East China Sea and the Taiwan Strait. Samples were collected using a NOR-PAC zooplankton net towed horizontally at a depth of 2 m, at eight stations along a transect, in March (spring) and October (autumn) 2005. The abundance of mesozooplankton was significantly higher during autumn than spring. Densities of many groups (e.g., Noctilucascintillans, pteropods, copepods, mysids, euphausiids, and other larva) increased in October. During both seasons, copepods represented more than 50% of the total zooplankton abundance. Noctiluca scintillans, appendicularians, and Calanus sinicus were dominant in spring, indicating their association with the cold waters of the East China Coastal Current. Appendicularians and N. scintillans were mainly associated with the coastal waters of Taiwan; whereas C. sinicus was concentrated in the offshore waters along the coast of Mainland China. Chaetognaths, Temora turbinata, Acrocalanus spp., and radiolarians were dominant in autumn, showing their association with the warm waters of the Kuroshio Branch Current. Oncaea venusta was relatively abundant during both seasons. Our study shows that, in addition to the influence of seasonal changes in the water masses, the distribution and composition of mesozooplankton are highly influenced by trophic interactions between zooplankton taxa, in the boundary waters of the Taiwan Strait and the East China Sea.

Magnesium in Drinking Water Modifies the Association Between Trihalomethanes and the Risk of Death From Colon Cancer

The objectives of this study were to (1) examine the relationship between total trihalomethanes (TTHM) levels in public water supplies and death attributed to colon cancer and (2) determine whether magnesium (Mg) levels in drinking water modify the effects of TTHM on risk of colon cancer development. A matched case-control study was used to investigate the relationship between the risk of death attributed to colon cancer and exposure to total trihalomethanes (TTHM) in drinking water in 53 municipalities in Taiwan. All colon cancer deaths of the 53 municipalities from 1998 through 2007 were obtained from the Bureau of Vital Statistics of the Taiwan Provincial Department of Health. Controls were deaths from other causes and were pair-matched to the cancer cases by gender, year of birth, and year of death. Each matched control was selected randomly from the set of possible controls for each cancer case. Data on TTHM levels in drinking water were collected from Taiwan Environmental Protection Administration. Information on the levels of Mg in drinking water was obtained from the Taiwan Water Supply Corporation. The municipality of residence for cancer cases and controls was presumed to be the source of the subject's TTHM and Mg exposure via drinking water. Relative to individuals whose TTHM exposure levels were <4.9 ppb, the adjusted odds ration (OR) (with 95% confidence interval [CI]) for colon cancer was 1.14 (1.01–1.28) for individuals who had resided in municipalities served by drinking water with a TTHM exposure ≥4.9 ppb. Evidence of an interaction between drinking-water TTHM and Mg intake via drinking water was noted. This is the first study to report an effect modification by Mg intake from drinking water in association between TTHM exposure and risk of colon cancer occurrence. Better knowledge of this modifying factor will help in public policymaking and setting health standards.

Isolation of Campylobacter sp in surface waters of Taiwan

Campylobacter sp is one of the main causes of human acute enteritis and diarrhea. It is commonly found in bird intestinal canal and pollutes water bodies through bird droppings. Clinically, detection of Campylobacter sp is by culture method and most are fecal samples. The objective of this study is to investigate the distribution of Campylobacter sp in river water of Taiwan. The detection of campylobacters in water by the United Kingdom Health Protection Agency was adopted and simplified. Water samples (1L) were enriched through membrane filters and selective enrichment Bolton broth. The mCCDA medium was used for culturing Campylobacter sp. In addition to using the selective media, DNA sequencing for species' identification was also included in this study. Campylobacter sp was detected in only 2 of 75 water samples, and 72 suspected strains were isolated from the selective mCCDA medium, in which several pathogenic bacteria included Escherichia coli O157. Not only there was pollution of Campylobacter sp in water environment but also other antibiotics-resistant pathogenic bacteria, which may cause public health risk.

Impact of Climate Change on Water Resources in Taiwan

This paper establishes a comprehensive assessment model to measure the regional impact of climate change on Taiwan's water resources. Working from future rainfall data simulated by Japan's high-resolution GCM model JMA/MRI TL959L60 in a SRES-A1B scenario, we first apply climate change to an assessment model of renewable water resources to estimate the volume of renewable water resources on a regional basis. We then conduct a water resources system simulation based on estimates of future water needs, regional reservoir effective capacity and renewable water resource volume. This paper uses three water resource assessment indicators: the annual water utilization ratio indicator, the water shortage indicator and the extreme event occurrence indicator. Through fuzzy comprehensive assessment, we divide the evaluation set into five levels: very good (L1), good (L2), fair (L3), poor (L4) and very poor (L5). Results indicate that, given the effects of future climate change (2080-2099) and the increase in water demand, future water resources conditions in northern and eastern Taiwan will not be significantly different from historical levels (1979-1998) and will maintain a ”good” level (L2), while the conditions in southern Taiwan will visibly deteriorate from its historical ”fair” level (L3) to ”poor” (L4); and the future conditions for central Taiwan will be ”poor” (L4). The initiation of adaptation options for water management in southern and central Taiwan would be needed by increasing reservoir capacity and reducing overall water use.

Population structure and expansion of kuruma shrimp (Penaeus japonicus) in the adjacent waters of Taiwan inferred from intron sequences

Sequence analyses on the specific intron from the elongation factor-1α gene were conducted to examine the population genetic structure and expansion of kuruma shrimp ( Penaeus japonicus ) off Taiwan. Five populations including 119 individuals were separately sampled from the north of East China Sea (ECS), west of Taiwan Strait (WTS), east of Taiwan Strait (ETS), South China Sea (SCS) and adjacent waters of Kagoshima (JAN). The gene diversity (h) was high for all populations (99.9%), with values from 99.7% (ETS) to 1. Nucleotide diversity (π) for all populations was 0.0421, with values from 0.0368 (JAN) to 0.0437 (ETS). Neighbor-joining tree and network of all alleles showed no significant genealogical structure. Analyses of molecular variance and F ST also revealed no significant genetic structure among five populations, but the F ST value between ECS and ETS was significant. Fu’s F statistics and analysis of mismatch distribution for overall alleles suggested that this species in the studied waters had experienced population expansion. Key words : Intron of elongation factor-1α gene, Penaeus japonicus, population genetic structure, population expansion.

Health risks for human intake of aquacultural fish: Arsenic bioaccumulation and contamination

Aquacultural tilapia (Oreochromis mossambicus L.) and shrimp (Penaeus monodon L.) from groundwater-cultured ponds in southwestern Taiwan were analyzed to estimate arsenic (As) bioaccumulation and the potential health risk to human intake. Most of aquacultural ponds exhibited higher arsenic than maximum allowed concentrations (50 μg L−1) in pond water of Taiwan. Arsenic levels in tilapia in Budai, Yichu and Beimen were 0.92 ± 0.52 μg g−1, 0.93 ± 0.19 μg g−1 and 0.76 ± 0.03 μg g−1, respectively and in shrimp was 0.36 ± 0.01 μg g−1 in Beimen. Total arsenic in tilapia is highly correlated (R2 = 0.80) with total arsenic concentration of pond water. Total arsenic in fish showed high correlation with that in bone (R2 = 0.98), head (R2 = 0.97) and tissue (R2 = 0.96). Organic arsenic species (DMA) was found higher relative to inorganic species of As(III) and As(V). The average percent contribution of inorganic arsenic to total arsenic in fish samples was 12.5% and ranged between 11.7 to 14.2%. Bioaccumulation factors (BAFs) for total arsenic in fish ranged from 10.3 to 22.1, whereas BAF for inorganic arsenic ranged from 1.33 to 2.82. The mean human health cancer risk associated with the ingestion of inorganic arsenic in the fish was estimated at 2.36 × 10−4 ± 0.99 × 10−4, which is over 200 times greater than a de Minimus cancer risk of 1 × 10−6. The mean human health hazard quotient associated with ingesting inorganic arsenic in the fish was 1.22 ± 0.52, indicating that expected human exposure exceeds the reference dose for non-cancer health effects by 22%. These results suggest that the inhabitants in this region are being subjected to moderately elevated arsenic exposure through the consumption of tilapia and shrimp raised in aquaculture ponds.

Estimates of life history parameters of the sharpspine skate, Okamejei acutispina, in the northeastern waters of Taiwan

The sharpspine skate Okamejei acutispina is one of the most abundant bycatch species of trawl fishing in the waters of northeastern Taiwan. However, its life history parameters, which are essential for stock assessment and management, are still poorly understood. The objective of this study was to estimate important parameters for this species, including age, growth, age at maturity and mortality. Age estimates were derived from 652 specimens (356 females and 296 males, 9.5–33.8 cm in disc width) using vertebral band counts and verified by length-frequency analysis of 1443 specimens (768 females, 675 males) collected between October 2004 and December 2007 in waters off northeastern Taiwan. The sexes-combined relationship between body weight (W) and disc width (DW) was W = 0.0193 × DW 3.0144 ( n = 1399, p < 0.05). Edge analysis indicated that a single growth band pair (comprising translucent and opaque bands) is formed each year, with up to 11 band pairs for females and 10 band pairs for males. The Robertson growth function had the best fit for both sexes and the growth parameters including 95% confidence intervals were estimated as follows: asymptotic disc width ( DW ∞) = 32.4 (31.3–34.0) cm DW, growth coefficient ( k) = 0.367 (0.315–0.426) yr −1 for females; and DW ∞ = 28.8 (27.6–30.3) cm DW, k = 0.365 (0.311–0.424) yr −1 for males. Age at maturity was estimated to be 7.2 and 6.8 yrs for females and males, respectively, while longevity was estimated to be 13.2 and 13.3 yrs, respectively. Length-frequency analysis produced similar results, supporting the vertebral aging estimates. Total mortality was estimated to be 0.85 and 0.86 yr −1, while natural mortality was 0.32 and 0.32 yr −1 for females and males, respectively. Our study indicates that it is likely that the sharpspine skate is at the margin of optimal exploitation and therefore close monitoring and seasonal closure management of trawl fishing are recommended to ensure sustainable utilization of this stock.

Sequential assimilation in the wind wave model for simulations of typhoon events around Taiwan Island

We investigate the effect of data assimilation in the Wind Wave Model (WWM, Hsu et al., 2005) for wind wave simulations of typhoon events using an Optimal Interpolation (OI) method in the coastal waters of Taiwan. The main point of the present study is that the assimilation is conducted for typhoon events with short-time periods around an island. Five real typhoon events were used for numerical assimilation experiments with different combinations of the key parameters: the correlation length, the ratio of the errors between the observation and the prediction, and the number of measuring stations. The retrieved wind velocity is obtained using the wave energy growth curve computed from the WWM. The wave energy dissipation function suggested by Makin and Kudryavtsev (1999) was adopted in the data assimilation. This study shows that assimilation can improve the initial performance of the wave model, but it becomes insignificant after about 12 h. In summary, the OI approach is shown to be a reliable assimilation scheme for the WWM applied to typhoon events in the coastal waters of Taiwan Island.